Question 1

What are good HCFC-225 Replacements?

Accepted Answer

The phase-out of the last major ozone-depleting solvent, HCFC-225, is underway. HCFCs were a “transitional chemistry” to ease industry’s conversion from old-style ozone-depleting solvents to ozone-safe cleaners. Made by Asahi, HCFC-225 is marketed under names including “AK-225” and “AsahiKlean.”

AK-225 is widely used as a carrier fluid, a defluxer, a metal degreaser, and to purge oxygen systems. It can clean PCBs, medical devices, metal parts and for cleaning optics, photonics and lasers. The fluid evaporates completely and leaves no residue.

Most cleaning is performed in a vapor degreaser. Replacement solvents can be used in the same equipment with the same methodologies. Temperature settings and process times may need some adjustment but a capital investment should not be necessary as long as the cleaning machine is in good working order.

HCFC-225 only is made in Japan and production there has shut down. In most of the world, HCFC-225 can no longer be imported or sold. Stockpiles may be used until supplies are exhausted. Users outside of the U.S. should investigate local regulations.

Better Alternatives:

Most companies will find the easiest transition to be an ozone-safe, nonflammable solvent. Customers using AK-225 should evaluate MicroCare HDS Heavy Duty Degreasing Solvent, MicroCare CCA General Purpose Degreaser, Vertrel® SDG Degreaser or Vertrel® MCA Plus.

Companies using AK-225AES, AK-225AMS or AK-225T, will find replacements like Vertrel® XP10 Drying Fluid or MicroCare® CMS Defluxer.

Lastly, if the factory was using HCFC-225ATE, AK-225ATMS, or AK-225TM, take a look at MicroCare HDS Heavy Duty Degreasing Solvent, the MicroCare CCA General Purpose Degreaser, Vertrel® SFR Defluxer, Vertrel® SDG Degreaser or Vertrel® MCA (this is particularly for cleaning liquid oxygen systems).

How to Convert:

MicroCare will help companies switch from HCFC-225/AK-225. The MicroCare team will ask questions about the current cleaning process, standards, materials of construction, soils, equipment, people, training, safety, throughput and other details. MicroCare then recommends a replacement. MicroCare provides liters for preliminary testing and large-scale testing at the MicroCare Critical Cleaning Lab.

Question 2

What is MIM?

Accepted Answer

MIM, or Metal Injection Molding, is a metalworking process where finely-powdered metal is mixed with binder materials to create a 'feedstock' that is then formed and hardened using injection molding. The MIM process allows high volume, intricate parts to be shaped in a single step.

Materials advances in MIM technology allow manufacturers to produce large quantities of parts with complex geometries, often eliminating labor-intensive machining completely. The quality and precision of parts made with MIM often results in parts requiring minimal subsequent machining to create a finished part with excellent dimensional repeatability.

Materials Used

The MIM process is capable of creating complex and precise structures by blending metal powder with various binding agents. Metals available include stainless steel, tool steel, and many other ferrous and nonferrous alloys. The actual process combines a polymer or wax known as a binder with a fine metal powder to form a moldable admixture that then is formed or molded into the desired structure.

Common types of binding agents are paraffin wax, carnauba wax, and specialty polyethylene waxes. The binding agents serve a critical purpose in the forming process but are ultimately sacrificial and must be removed once the structure is formed. Selection of a debinding method is a balance of removing the wax binder in the shortest amount of time and with the least amount of damage to the structure because as the binder is removed, the structure becomes fragile.

Binder Removal

Extraction of the binder can be done in either the solvent vapor or liquid phase in a vapor degreaser. Both rely on the debinding fluid flowing through the pores of the structure to dissolve the wax. This is where the physical properties of the debinding fluid become important. The ideal debinder will be nonflammable, have a low surface tension and low viscosity to clean internal geometries better. It should also be 100 percent volatile so the debinding fluid can be easily removed before sintering. Once the debinding fluid is fully removed from the part structure, the parts are then thermally sintered under high heat to bond the metal powder into its finished solid mass state. The remaining binder in the parts is essentially burned off at sintering temperatures.

Debinding Fluids

Debinding fluid blends have been developed to speed the debinding process without the use of n-propyl bromide, methyl pyrrolidone, polyethylene glycol, heptane, or trichlorethylene, which all carry health and or environmental baggage. Two recommended debinding fluids include Tergo™ MCF Metal Cleaning Fluid and Opteon SF79 Specialty Fluid. These debinding fluids boast low viscosity and surface tension ratings, are nonflammable, and are engineered for selectivity so just the right amount of binder is removed without damage to the parts structure. Their lower boiling point still melts wax and additives but runs more efficiently in the vapor degreaser. It also evaporates from inside the pores of the parts faster, saving energy costs and speeding drying times. The debinding fluids are also distilled and reused many times inside the vapor degreaser before replacement is needed. They also do not require acid acceptance testing, maintenance or additional stabilizers.

Question 3

Why Consider a Vapor Degreaser?

Accepted Answer

A properly designed, operated and maintained vapor degreasing process offers many advantages. Vapor degreasers and modern, sustainable cleaning fluids:

Use minimal floor space
Minimize energy consumption
Minimize solvent consumption
Distill and recycle the solvent for continued use
Minimize waste disposal
Minimize chemical exposure
Provide consistent, reproducible cleanliness performance
Can be completely automated
Are easy to maintain
Do not require a chemist to run
Can easily clean complex configurations
Have the lowest cost per part cleaned

Question 4

What Does Vapor Degreaser Hardware Cost?

Accepted Answer

Equipment costs vary widely, so it’s a little hard to provide an exact answer. It’s important to note that these systems have incredible through-put. While a $100,000 aqueous system is on the small size, for the same amount of money you can get a complex, full-featured, high-capacity solvent cleaning system and still have lower operating costs. Here are some general guidelines that might be useful:

Vapor Degreaser Equipment Costs

A very small benchtop sized system with one cleaning chamber and holding less than two gallon/8 liters of cleaning solvent will cost about $20,000.

A small to medium-sized, floor-mounted batch system with two chambers and a water separator is going to cost about $50,000-$75,000. At the higher price the machine should include a hoist, advanced programmable controls and some extra cleaning features.

A large, floor-mounted batch system with three chambers and all sorts of bells and whistles is going to cost about $100,000.

A large, floor-mounted in-line system with the very highest capacities and speeds is going to cost more than $250,000.

A large, floor-mounted “zero emission” or “low emission” system is going to cost about $250,000. These systems are popular in Southern California.

Vapor Degreaser Installation Costs

Installation costs are a large part of the cost of any cleaning system. In addition to the actual cost of the machine, these costs include freight, site preparation and set-up costs. Most engineers also include building renovations, ventilation enhancements, electrical upgrades and water-treatment subsystems required to support the new system. For most degreasers these costs are almost invisible because vapor degreasers tend to be small and their infrastructure requirements are almost nil.

Another consideration is the actual cost of the space required by the cleaning machine and the support systems it requires. Since solvent systems are usually far smaller than aqueous and semi-aqueous systems many engineers skip this step, but a “footprint factor” of 4X would be a reasonable rule-of-thumb. To estimate floor space costs, call your financial people and ask them for the “fully-loaded per-foot costs” for the space in which you are interested. This usually will be expressed as a “triple-net” rent per square foot.

Total one-time costs should be “allocated” to reflect the productivity of the machine over its expected economic lifespan. For example, if the machine is planned to clean 10,000 parts per year for ten years, it will clean a total of 100,000 parts in its economic lifespan. The total one-time costs should be divided by the throughput (in this case, 100,000 parts) to calculate the true “total capital costs per part cleaned.”

One-Time Capital Costs for Vapor Degreasers

Here is a short list of capital expenses to consider when selecting a vapor degreaser:

Cost of the Cleaning System Itself
Freight & Insurance to Get It Delivered
Site Engineering & Architectural Planning Costs (usually nominal)
Construction (usually nominal)
Electrical Changes (usually nominal)
Water/Plumbing (not normally required)
Ventilation (not normally required)
System Set-Up
Cost Per Square Foot of the Total Required Floorspace
Cost of Capital

For more ideas and suggestions, contact the manufacturers of the vapor degreasers and get their expert insights on the cost comparisons. Remember to ask about the numerous options and add-ons which can dramatically reduce the daily operating cost of a vapor cleaning system. MicroCare has prepared a cost-comparison worksheet in Excel format which can help illuminate the truth costs of different cleaning systems.

There are a number of accesories which can be added to vapor degreasers to improve cleaning performance and lower costs, including automated hoists (shown here), superheat, and ultrasonics in the rinse tank

Question 5

How Does Vapor Degreasing Work?

Accepted Answer

Vapor degreasers actually are pretty simple machines. They use a straightforward thermo-mechanical process — boiling and condensing a low-boiling cleaning fluid — in conjunction with some clever hardware design to deliver high quality cleaning quickly, consistently, easily and inexpensively.

The Vapor Degreaser Design

A vapor degreaser is a special type of still. In the simplest form, the degreaser boils a cleaning fluid into vapors and fumes. Because warm vapors are lighter (less dense) they rise upwards in the machine but are trapped by a layer of refrigeration which creates a temperature inversion. The vapors then condense back into liquid form and returned in to the cleaning machine to be re-used. The schematic below illustrates the basic flow of the system.

As the schematic shows, there always is fresh cleaning fluid in the rinse sump. As additional freshly-distilled cleaning fluid is returned from the cooling coils back into the system, it always is returned to the rinse sump. The rinse sump gradually overflows into the boil sump, which is where the heaviest cleaning is performed and where the contamination becomes concentrated.

cross section of Vapor Degreaser

Important point to understand, and unlike aqueous cleaning: the cleaning fluid never wears out. Because the cleaning fluid is constantly being repurified and recycled, it is used hundreds or even thousands of times. This makes vapor degreasing very, very affordable.

It’s important to note that “boiling” does not imply a lot of heat. Most MicroCare, Opteon, Vertrel and Tergo cleaning fluids boil at very mild temperatures, usually between 40˚C/105˚F and 65°C/165°F, depending upon the exact formulation. Low temperatures enhance worker safety and also keep energy costs down. In fact, many modern vapor degreasers operate on 25 amps or less.

As you might expect, there are dozens of variations and improvements on this very simple process, such as adding ultrasonics, but all of those enhancements are merely upgrades to these basic three steps. It’s fast, simple, fool-proof, and safe cleaning design.

Details of Vapor Degreaser Design

Most degreasers have two tanks or sumps: a boil sump and a rinse sump. The schematic below explains the design in more detail.

Everything starts in the boil sump. That’s where most of the heavy-duty cleaning occurs. The heating coils tucked underneath the sump warm the cleaning fluid to it’s boiling point; the tumbling action of the boiling fluid enhances cleaning. Also, as the cleaning fluid boils it creates vapors (think, steam, but steam made from cleaning fluid not water). The saturated fluid vapors sit above and across the two solvent sumps. Because they’re warm, they tend to rise upward within the machine.

Vapor degreasing schematic showing the manner in which the system operates

Above the sumps and the fluid vapors there should be two layers of cooling coils. These coils create a zone of cold, dry air over the machine; a temperature inversion. The warm vapors cannot punch through this barrier; this “cold trap” prevents the vapors from simply rising out of the machine unhindered. Stuck in the machine, these vapors quickly come into contact with the cooling coils. The vapors condense back into liquid and flow into the water separator (“distillate”) and then back into the rinse sump.

The rinse sump contains only pure, freshly distilled cleaning fluid. This is used to rinse the parts of any last vestige of contamination. Since the rinse sump constantly is having cleaning fluid added to it, from the water separator, it quickly overflows. The excess cleaning fluid flows into the boil sump, completing the recycling loop.

(Special note: The water separator sits along side the machine. Since the degreaser is constantly chilling vapors, it collects water out of the air. This water needs to be removed for fast, spot-free cleaning.)

Using a Vapor Degreaser

There are only a few steps to using a vapor degreaser:

Place the products to be cleaned in a basket.
Slowly lower the parts into cleaning fluid vapors above the boil sump for the first few moments of cleaning. The vapors condense on the (relatively) cool parts and cleaning starts. Any liquid cleaning fluid drips off of the parts and falls back into the boil sump.
Continue lowering the parts into the boil sump. The cleaning fluid wraps around the parts, goes into and out of the tightest spaces, and dissolves oils, greases and fluxes. This is where the heavy cleaning occurs. Notice the gentle nature of vapor cleaning: there are no high-pressure sprays, no air knives, no high temperatures stressing the components. It’s simple, fast and easy.
Remove the parts from the boil sump and move them into the rinse sump. Here, fresh, pure distilled cleaning fluid removes any final vestige of the contamination.
Once rinsing is complete, slowly remove the parts from the rinse sump, up through vapors, and remove them from the machine. The parts come out clean, dry and relatively cool, ready for the next manufacturing process.

There are many additional features and accessories which are available from the various equipment manufacturers. Savvy engineers will review their options to insure they get the machine which will provide optimal performance at the lowest total cost per part cleaned.

Summary

Vapor degreasing with modern, planet-friendly MicroCare cleaning fluids delivers the highest quality of cleaning in the shortest possible time, with the least risk of damage to the components. Wherever there are demanding specifications or challenging environmental issues, the MicroCare answers and a vapor degreaser are the ideal combination. These are great replacements for old-style aqueous cleaners as well as old-style hazardous solvents like TCE, nPB and Perc.

Question 6

Why Is Vapor Degreasing Better for Critical Cleaning than Other Technologies?

Accepted Answer

Customers choose MicroCare cleaning fluids because they make cleaning easy, fast, consistent, safe and reliable. All of these factors combine together to make vapor degreasing with MicroCare fluids more affordable than any other critical cleaning technology.

MicroCare nonflammable solvents are used in special, engineered cleaning systems called “vapor degreasers.” For a vapor cleaning to work, you need both a special solvent and one of these special machines. It’s the combination of “solvent+system” which makes for a highly effective cleaning process.

To contrast a vapor degreaser with a competing aqueous cleaning system, the aqueous system will tend to be:

much larger than the solvent cleaner to accomplish the same cleaning tasks, plus it will be
more complex to buy and to operate,
require more complex waste-handling subsystems,
more expensive,
consume more energy,
take up more floor space, and
clean more slowly than a similarly-sized vapor degreasing cleaning system.

So, when looking at the total cost per part cleaned the solvent system is simply less expensive to buy and operate.

Vapor degreasing systems also are versatile. They are able to clean in many applications where water simply doesn’t work. MicroCare fluids can accomplish tasks that water simply can’t do, such as removing water from complex shapes, cleaning under tight components and depositing lubricants onto precision surfaces. At some point, the price isn’t the issue — it’s simply “getting the job done.”

Worker safety is another important criteria at which the MicroCare family of cleaning solvents and vapor degreasers come out on top. The basic solvent is nonflammable, nonconductive, non-corrosive, and all the other “non’s” you can think of. Plus, vapor degreasing is an inherently safe process. So a properly engineered and operated degreaser with a MicroCare fluid is a very safe system indeed.

The environment is another important issue where MicroCare products win. Today’s solvents are completely ozone-safe; and many of the new products are so new as to not even be listed in the Montreal Protocol. Many of the blends have low VOC content which helps prevent the formation of smog over our cities. Other choices have very low global warming indices which protect the planet. Plus — and this is big — a cleaning machine using a MicroCare fluid doesn’t use any of our scarce water supply, very little expensive electricity and returns almost no hazardous waste. These are very clean machines, in every sense of the word.

In short, when it comes to precision cleaning, the team at MicroCare really deliver the best of all possible worlds.

MicroCare Sr. VP Jay Tourigny and Chemist Venesia Hurtubise operate a medium-sized Branson vapor degreaser equipped with an automated hoist

Operators use a medium-sized Branson vapor degreaser equipped with an automated hoist

Question 7

What Is AK-225 and Can I Use It for Cleaning?

Accepted Answer

AK-225 is also called HCFC-225 and has now been phased-out across most of the world. It would not be a good choice for modern cleaning processes.

To be fair, it has a few good points. It’s a moderately powerful. It works well in vapor degreasers. It is not flammable. It is not as aggressive on plastics as some other popular cleaners. Perhaps most importantly, it is not classified as a Volatile Organic Compound (VOC) so the air-quality regulators in Southern California think it is an excellent choice.

So what are the problems? First and foremost, HCFC-225 is an ozone-depleting substance. Specifically, it is a Class II Ozone-Depleting Substance under the U.S. Clean Air Act. It’s banned in Europe and the U.S. HCFC-225 also was has a fairly limited product line, with very few blends to enhance or expand the cleaning range of the product. So after doing all the work to specify a new cleaner, you soon will be faced with repeating the project to specify something that is available today and completely ozone-safe.

In our humble opinion, HCFC-225 is yesterday’s news. Select the MicroCare, Opteon, Vertrel or Tergo cleaners for a process you can use today, tomorrow and for years to come.

Question 8

What Is a 'Wetting Index' and What Does It Tell Me About a Solvent and Cleaning Results?

Accepted Answer

MicroCare vapor degreasing products are the best choice for precision cleaning of difficult shapes and awkward pieces. The reason for this success is the very low surface tension, high density and low viscosity of the different fluids:

A low surface tension means the solvent can get into tight spaces more easily than solvents with high surface tensions (like aqueous systems);
A heavy solvent literally can float away contamination that other types of cleaning agents cannot move;
A solvent with low viscosity flows in and around objects more effectively than solvents with high viscosity (think molasses, or maple syrup).

This BGA chip on a printed circuit board has a 2 mil stand-off from the substrate. Modern solvents can clean beneath this component but aqueous cleaning systems will struggle to get into such tight spaces

A clever way to understand all these different measurements is to combine the three most critical factors into a single index. MicroCare recommends combining the density of the solvent, the viscosity of the solvent and the surface tension into an index score. We call this the wetting index. With the wetting index, the higher the score the better the cleaning.

The formula for computing a wetting index is:

(Density x 1000)

divided by

(Surface Tension x Viscosity)

In particular, the wetting index is a superior predictor when comparing particulate cleaners. It’s simply a better yardstick to use when selecting a solvent for applications in which the object is not to dissolve the contamination but to float it away. Here’s how the numbers rack up:

Not-In-Kind Benchmarks

Brand Name or Description	Liquid Density (kg/liter)	Surface Tension (dyne/cm)	Viscosity (cP)	Wetting Index
Water	1.00	73	1.00	14
IPA Alcohol*	0.79	22	2.40	15

First Generation

Brand Name or Description	Liquid Density (kg/liter)	Surface Tension (dyne/cm)	Viscosity (cP)	Wetting Index
Trichloroethylene (TCE or Trike)	1.46	29	0.58	87
Perchloroethylene (PCE or Perc)	1.62	35	0.88	53
Freon™ TF†	1.57	17	0.70	132

Second Generation

Brand Name or Description	Liquid Density (kg/liter)	Surface Tension (dyne/cm)	Viscosity (cP)	Wetting Index
Genesolv® 2004†	1.23	19	0.43	151
AK-225†	1.55	16	0.59	164
Bromothane™ (nPB)	1.35	26	0.49	106

Third Generation

Brand Name or Description	Liquid Density (kg/liter)	Surface Tension (dyne/cm)	Viscosity (cP)	Wetting Index
Novec® 71DA	1.33	16	0.45	185
Vertrel™ XF	1.58	14	0.67	168
MicroCare™ HDS	1.32	195	0.57	122
Vertrel™ SFR	1.28	21	0.42	145

Fourth Generation

Brand Name or Description	Liquid Density (kg/liter)	Surface Tension (dyne/cm)	Viscosity (cP)	Wetting Index
Opteon™ Sion/SF79	1.28	21	0.42	145
Solstice® PF	1.26	13	0.45	215
AE-3000	1.35	16	0.34	248

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

So here’s the short answer: when it comes to tough cleaning problems, the huge family of MicroCare cleaners are a great choice. They are great replacements for ozone-depleting solvents such as CFC-113, 1,1,1-trichloroethane, HCFC-141b and HCFC-225, as well as high-global-warming solvents such as perfluorocarbons (PFCs).

Question 9

How Can Cleaning with Vapor Degreasers Save Electricity?

Accepted Answer

The energy efficiency of vapor degreasing is one of the main advantages of solvent cleaning when compared to water cleaning. Water cleaning uses a great deal of electricity while solvent cleaning uses far, far less. For customers in locations where electricity is expensive, vapor degreasing is the most energy efficient and affordable way to clean. Additionally, burning fossil fuels to create electricity is one of the primary contributors to global warming, so saving electricity is good for your budget and the planet.

Energy-Intensive Aqueous Cleaning

There are four design features in every aqueous cleaning system which make them very energy-intensive. These are:

Power to the numerous, high-pressure pumps which move the water around the machine, and the machines can be huge;
The energy it takes to heat the cleaning water,
The energy it takes to dry the parts, and lastly
The energy it takes to treat and purify the water for re-use or disposal.

All of this additional work is required because of the inherent nature of the molecule of water. Basically, water has both a high surface tension and a high latent heat of evaporation. These are characteristics that no amount of fancy engineering can change. Consider these three fundamental characteristics:

High surface tension is a problem for water cleaning. It stops the water from going into tight spaces. That’s why users first need (a) to heat the water, and then (b) then they need to use additives to boost the cleaning power and reduce surface tension, and finally they need (c) those big pumps to spray the water-and-additive mix in to tiny components.

Then, the high latent heat of evaporation causes still more problems because this makes water a slow-drying cleaner. It takes a lot of heat and big, energy-sucking air knives to remove the aqueous residuals from the components.

At this point, the water has picked up the contamination — in addition to the cleaning additives, the water may now be holding oils, fluxes, lead from the PCBs and so on. That water, the additives and the contamination now must be treated in a waste-water treatment system to re-purify the water. Normal treatment facilities include reverse-osmosis systems and multiple stacks of de-ionizing filters. Obviously, this takes more electricity and more pumps to move the waste water through these cleansing processes.

Energy-Efficient Vapor Degreasing

In general, modern, nonflammable solvents have low surface tension, low viscosity, high density and low latent heat. This means they’re going to clean more easily, with less heating, fewer pumps, no air knives and so on. There is no water to heat, which saves electricity. Instead the solvent is heated to just above room temperature, which takes very little electricity.

There are no big pumps required to push the solvent around, which saves electricity. Instead, the solvent moves by gravity.
There are no blowers or “air knives” on vapor degreasers, which saves electricity. The solvent is retained inside the machine and the parts being cleaned come out dry. (In fact, even motorized fans and fume hoods are not recommended near vapor degreasers because it increases solvent losses, so electricity is saved there, too.)
There is no waste treatment facility required, which saves electricity, because the degreaser is automatically, inherently and continuously re-purifying and re-distilling the solvent.
There is no humidity added to the factory environment, so air conditioning and environmental loads are reduced.

The net result is that the typical vapor degreaser uses about 30 amps or power when cleaning and one-tenth of that energy in stand-by (night) mode; many of the smallest machines use standard household electrical connections! This contrasts with water-cleaning systems with power consumption is measured in hundreds and thousands of amps, and often require 440 volt circuits and big power panels to manage the electrical load.

This is one case where simpler really is better.

Chris Jones demonstrates a vapor degreaser

Question 10

Why Do Heavy, Dense Solvents Clean Better than Lighter Fluids?

Accepted Answer

Most people are familiar with the basic process of cleaning: a solvent dissolves the oil, grease, flux or some other contamination and then the contamination is rinsed away. The key is dissolving: just like sugar “dissappears” in warm water, solvents need to dissolve most contamination to remove it.

However, sometimes the contamination cannot be dissolved. In this case, dense solvents are better cleaners than lighter solvents, all other factors being equal. This is called “displacement cleaning.”

Water is heavy, but modern cleaning fluids are heavier — typically 20-30% heavier than water, and 50%+ heavier than alcohol.

Many types of contamination are not soluble, so no amount of cleaning fluid or water can remove them by dissolving them. Examples include solder balls, metal finings from grinding processes, tiny particles of dust and dirt, lint, exhaust particulate, skin cells, and many other common contaminates.

However, modern nonflammable cleaning fluids generally are much, much heavier than water. That means these fluids remove such types of contamination: they “float” the dust and grit off the surface just as a ship floats on the ocean. This means the cleaning fluids get under particulate, dissipate any static charge and lift particulate off the surface. Water and IPA both lack this capacity. Here’s how the numbers stack up:

Not-In-Kind Benchmarks

Brand Name or Description	Principle Supplier	Base Chemistry	Liquid Density (kg/liter)
Water		H20	1.00
IPA Alcohol*		Alcohol	0.79

First Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Liquid Density (kg/liter)
Trichloroethylene (TCE)		Chlorine	1.46
Perchloroethylene (PCE or Perc)		Chlorine	1.62
Freon™ TF†	DuPont	CFC-113	1.57

Second Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Liquid Density (kg/liter)
Genesolv® 2004†	Allied-Signal	HCFC-141b	1.23
AK-225†	Asahi	HCFC-225	1.55
n-Proply Bromide (nPB)		Bromine	1.35

Third Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Liquid Density (kg/liter)
Novec® 71DA	3M	HFE-7100	1.33
Vertrel™ XF	Chemours	HFC-43-10	1.58
MicroCare™ HDS	MicroCare	HFC-365	1.32
Vertrel™ SFR	Chemours	Trans	1.28

Fourth Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Liquid Density (kg/liter)
Opteon™ SF79	Chemours	MPHE	1.28
Solstice® PF	Honeywell	HFO-1233zd	1.26
AE-3000	Asahi	HFE-347pc-f	1.35

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

From this chart, one can easily see that modern, nonflammable, planet-friendly cleaning fluids are heavier than water or IPA, and therefore will generally out-perform those fluids in critical cleaning applications. When combined with other important factors, such as Kb value, toxicity, flammability and surface tension, these predict better, faster and more cost-effective cleaning.

Question 11

How Does the Surface Tension of a Solvent Affect My Cleaning Results?

Accepted Answer

MicroCare precision cleaners are the best choice in the industry for cleaning difficult shapes and awkward pieces. The reason for this success is the very low surface tension these products exhibit.

Surface tension is the cohesive behavior of a liquid in which the molecules of the liquid are more attracted to each other than to the surfaces around it. This is an “attractive force” and is exerted upon the surface molecules of a liquid by the molecules beneath the surface. The behavior we all see and know is when the liquid forms itself into a shape having the smallest surface area.

High surface tension liquids, like water, form three-dimensional balls or bubbles, as in the photo on the right. Low surface tension materials spread out, flowing across a surface and exhibit very little three-dimensional height.

Water droplets on a plants leaf are a good demonstration of the surface tension of water

We experience surface tension is a thousand ways, every day. Every time we wash the dishes or take a shower, we add soap to the water to lower the surface tension of the water so that it more readily soaks into pores and soiled areas. The water strider is an insect which can walk on the surface of water because their weight is not enough to penetrate the surface. Many camping tents are somewhat rainproof in that the surface tension of water will bridge the pores in the finely woven material. But if you touch the tent material with your finger, you break the surface tension and the rain will drip through. And, interestingly, cold water has more surface tension than hot water, which is why hot water cleans better than cold water.

Surface Tension Affects Precision Cleaning

When it comes to precision cleaning, especially in a vapor degreaser, cleaning fluids with lower surface tension will out-perform high-surface tension fluids. Lower surface tension means the cleaning fluid can get into tight spaces easily. It directly affects the ability of the cleaning fluid to wet a surface, and obviously you can’t clean if you can’t wet.

Here’s how the numbers compare:

Not-In-Kind Benchmarks

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Water		H20	73
IPA Alcohol*		Alcohol	22

First Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Trichloroethylene (TCE )		Chlorine	29
Perchloroethylene (PCE or Perc)		Chlorine	35
Freon™ TF†	DuPont	CFC-113	17

Second Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Genesolv® 2004†	Allied-Signal	HCFC-141b	19
AK-225†	Asahi	HCFC-225	16
n-Propyl BRomide (nPB)		Bromine	26

Third Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Novec® 71DA	3M	HFE-7100	16
Vertrel™ XF	Chemours	HFC-43-10	14
MicroCare™ HDS	MicroCare	HFC-365	19
Vertrel™ SFR	Chemours	Trans	20

Fourth Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Opteon™ SF79	Chemours	MPHE	21
Solstice® PF	Honeywell	HFO-1233zd	13
AE-3000	Asahi	HFE-347pc-f	16

Tergo™ Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Surface Tension (dyne/cm)
Tergo™ XCF2	MicroCare	HFO-110	22
Tergo™ XCF3	MicroCare	HFO-110	21
Tergo™ GCF	MicroCare	HFO-110	18

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

A higher surface tension means the product will deliver better cleaning.

So here’s the short answer you were probably looking for: when it comes to tough cleaning problems, modern, nonflammable cleaning fluids are a far better choice than old-style aqueous cleaners. The modern cleaning fluids have less environmental baggage than the old-style solvents and are great replacements for ozone-depleting solvents such as HCFC-225, toxic solvents such as TCE and the high-global-warming solvents such as perfluorocarbons (PFCs).

Question 12

What Is a 'Kb Value' and What Does It Mean?

Accepted Answer

Kb value refers to a standardized ASTM test that measures the relative strength of a non-aqueous cleaning fluid. The test involves measuring the solubility of a very specific type of contamination, called “kauri gum.” Kb values range from 10 (very mild) to 200 or even higher (very strong). Mild solvents with lower Kb values will may not be strong enough to dissolve ionics and fluxes. Cleaning fluids with higher Kb values may be speedy and effective cleaners but may attack plastic components. The Kb values for the MicroCare products generally range from 20 to 119.

It is difficult to predict the cleaning effectiveness of a fluid without tests. The results of a cleaning process can vary by the contamination, the selected cleaning fluid, the application, the cleaning system and the physical shape of the parts being cleaned. The MicroCare Critical Cleaning Lab is capable of conducting cleaning tests for clients to determine the optimal cleaning fluid for the contamination being removed.

Kb Values

Not-In-Kind Benchmarks

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Water		H20	n/a
IPA Alcohol*		Alcohol	15

First Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Trichloroethylene (TCE)		Chlorine	133
Perchloroethylene (PCE or Perc)		Chlorine	90
Freon™ TF†	DuPont	CFC-113	31

Second Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Genesolv® 2004†	Allied-Signal	HCFC-141b	56
AK-225†	Asahi	HCFC-225	31
n-Propyl Bromide (nPB)		Bromine	129

Third Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Novec® 71DA	3M	HFE-7100	33
Vertrel™ XF	Chemours	HFC-43-10	14
MicroCare™ HDS	MicroCare	HFC-365	48
Vertrel™ SFR	Chemours	Trans	101

Fourth Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Opteon™ SF79	Chemours	MPHE	103
Solstice® PF	Honeywell	HFO-1233zd	25
AE-3000	Asahi	HFE-347pc-f	38

Tergo™ Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Kb Value
Tergo™ XCF1	MicroCare	HFO-110	44
Tergo™ XCF2	MicroCare	HFO-110	118
Tergo™ GCF	MicroCare	HFO-110	38

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

pH Versus Kb

People often ask about the pH of a cleaning fluid, because everybody knows the pH of a fluid can be a good indicator of cleaning strength. It is — but the pH test only works for fluids containing water. For non-aqueous fluids a better measure of cleaning effectiveness is the Kauri–Butanol (Kb) value. Let’s compare these two measurements.

What is pH? First introduced by S.P.L. Sørensen in 1909, pH measures the acidity or alkalinity of a fluid in comparison to water. The range goes from 0 – 14, with 7 being neutral (water). A pH lower than 7 indicates an acidic fluid (which means it has more hydrogen ions than plain water) while a pH greater than 7 indicates a basic, or alkaline, fluid (more hydroxyl ions than standard water). Most aqueous cleaning systems use alkaline cleaning agents, often with pH ratings around 12-13. So for contamination that is water-soluble, looking at the pH makes sense.

But many types of contamination are not water-soluble so non-aqueous cleaning fluids are a better choice for those cleaning jobs. Non-aqueous cleaning fluids are neither acidic nor alkaline; the pH test simply isn’t relevant because non-aqueous cleaning fluids don’t contain any hydroxyl ions or hydrogen ions. So Kb value is the alternative measurement.

Kb value refers to a standardized ASTM test (Method D-1133) that attempts to calibrate the relative strength of a cleaning fluid by dissolving a gummy resin called Kauri gum (see note, below). The benchmark for the test is butanol solvent. The working ranges of Kb values go from 10 (very mild) to 200 or even higher (very strong). For years, this has been used to judge the relative cleaning “power” of cleaning fluids used on fluxes found on electronics, metals, optics and elsewhere.

Limitations of Kb Values

While it is convenient to state that higher Kb values indicate a “stronger” cleaning fluid, it is not that precise. There are many limitations to the Kb test. For example, the test must be performed at 25°C (77°F) and one atmosphere pressure. Conducting the test under other conditions yields different results. Some cleaning fluids cannot be evaluated using the Kb method since they dissolve the kauri gum almost instantly. Certain types of fluxes, such as OA fluxes and some synthetics, simply don’t react predictably to the Kb test. The test can produce some exotic results especially with alcohol formulas. Real-world cleaning results also can be affected by other factors such as surface tension, density and viscosity. Also, the original Kb test calibrated petroleum products (butanol, hence the name Kauri-butanol test) but now it has been stretched to measure brominated, fluorinated, chlorinated, and other liquids. In other words, people are asking the Kb test for to do more than it can consistently provide.

So, there is a general relation between the Kb value of a cleaning fluid and its capacity to clean fluxes, oils and grease. Most product specifications for cleaning fluids include a Kb value in one form or another. Cleaning fluids with lower Kb values may displace particulates but but may not be strong enough to handle grease, ionics and fluxes. Cleaning fluids with higher Kb values may be speedy and effective flux removers but may attack plastic components or remove inks.

Many other factors affect cleaning performance as well: surface tension and density affect wetting; toxicity and flammability affect the handling of a material; costs certainly drive the economic analysis. Therefore, while the Kb value is a handy benchmark and a good starting point for an analysis, a Kb number — like a pH value — is only a the first of many predictors of cleaning performance. Selecting a cleaner with the optimal Kb value is a balancing act with numerous trade-offs.

In short, we use the term Kb Value and we know the test method, but it should only be considered an approximation that needs to be validated with real-world cleaning tests. MicroCare offers a large family of cleaning fluids with a variety of Kb values, which enables engineers to fine-tune their cleaning process.

Note: What Is Kauri Gum?

The benchmark resin used in the Kb test actually is the sap from the kauri tree (Agathis Australis) that only grows in New Zealand. In the 1890s, chemists searched for a solvent to liquefy kauri resin to make it useful industrially, particularly in the furniture finishing industry. They found that kauri gum was easily dissolved in butyl alcohol (butanol) so that became the benchmark solvent and is the source of the name of the test, the Kauri-Butanol test.

Question 13

Are There Any Materials Compatibility Problems with MicroCare Solvents?

Accepted Answer

General, materials compatibility is not an issue with the MicroCare cleaners, but make no mistake — materials compatibility can be a complex question. In general, the higher the Kb value of the solvent, the more likely the material will have some compatibility issues.

For example, Vertrel™ XF has almost no compatibility problems with any substrate. It has a very mild Kb value, around 20. On the other hand, the strongest cleaners have good materials compatibility across fiber glass, resins, plastics, ceramics, glass and metals like zinc, stainless steel, carbon steel, aluminum and copper, but will instantly destroy soft plastics such as polycarbonates. For example, some of the transparent coatings on electronic mobile and hand-held devices.

Gaskets and elastomers also will demonstrate some swelling but will, in most cases, revert to within a few percent of original size/weight after air drying. Swell, shrinkage, and extractables are strongly affected by the compounding agents, plasticizers, and curing processes used in the manufacture of plastics and elastomers. Therefore, thorough testing prior to use of any cleaner is particularly important.

Materials compatibility is not limited to solvents based on synthetic molecules. For example, d-liomene is a powerful, natural solvent made by every green plant. It will chew up elastomers and rubber in the blink of an eye.

If you have questions about specific plastics or elastomers, check the individual product spec sheets or contact MicroCare to have our Critical Cleaning Lab run some tests. Those tests will eliminate a great deal of uncertainty about your products, components and problems.

In short, MicroCare offers a wide range of specialty fluids so materials compatibility usually is not a major factor.

Parts made with soft plastics, rubbers and elastomers may be damaged by exposure to aggressive solvents with high Kb values

Question 14

How Can I Monitor My Workers' Exposures to Solvent Fumes?

Accepted Answer

Fumes from some nPB-based cleaning fluids can be hazardous if there is significant over-exposure to the fumes. Monitoring the fumes is an important part of a company’s worker safety program. The hazards associated with n-propyl bromide vary by the extent of the exposure. Short-term over-exposure can lead to skin and eye irritation, dizziness or headaches. Long-term tests show effects on fertility in laboratory animals.

First, let’s remind everybody that proper storage, usage and handling procedures, including drum pumps and personal protective equipment, should be used to avoid short-term overexposures especially when there is the potential for splashing or skin contact. Suitable eye protection should be worn to protect against eye contact.

All nPB users should also conduct a simple workplace exposure test using air-monitoring badges to assure worker safety. The use of the badges and the collection of this data memorializes worker exposure levels and to some degree immunizes a company’s against liability in the event of a spurious health claim.

Badges also are available for the HFC and HFE solvents as well, but their toxicity ratings are much higher (safer) than nPB cleaners so these badges are rarely used.

Exposures badges are an easy way for the employee to go about their daily routine while wearing the badge to determine the exposure to a chemical. After wearing the badge for 8 hours, the badge is sent to an independent lab to determine exposure levels.

This shows an air quality monitoring badge used for measuring the nPB vapors in the air around the environment of the vapor degreaser.

Question 15

What Is the Shelf Life of MicroCare Flux Removers??

Accepted Answer

MicroCare flux removers generally do not have any shelf life restrictions. In other words, MicroCare products have an indefinite or unrestricted shelf life. This guarantee means that if the products are unopened, properly handled and carefully stored they will remain safe and effective for use for many years.

The date of manufacture is printed on the bottom of every aerosol can. The date of manufacture can also be determined by the lot number which is printed on the bottom of every aerosol can and pre-saturated tub and refill as well as on the outside of each case. Lot numbers are printed on the product labels for gallon, pail, and drum product. The first two digits represent the year in which the solvent was manufactured (e.g. lot number 21213 was manufactured in 2021 and lot number 17182 was manufactured in 2017).

The last three digits represent the day of the year; this can be calculated using the Julian Code (e.g. 21213 was manufactured in 2021 on the 213th day of the year).

If you have any questions, please feel free to contact MicroCare.

“Proper” handling is defined as a reasonably cool, dry location out of direct sunlight and away from extreme heat. Any business facility in which people work comfortably is sufficiently cool. Unacceptable locations would be (a) outside exposed to rain; (b) on a hot loading dock exposed to direct summer sunlight for weeks at a time; or (c) in an unheated truck during winter months in Stockholm, just to pick a few examples. Also, do not store metal containers directly on concrete floors or the containers will rust. MicroCare is not responsible for products improperly stored.

Obviously, as soon as the container is opened the shelf life of the product is reduced. Opened containers should be used first and emptied as soon as practicable. It is common and unremarkable to find unopened containers of Micro Care products which work well after five and even eight years in storage.

Micro Care is aware that few companies in the industry offer an unlimited shelf life warranty. But we are extremely comfortable with our products, packaging and manufacturing processes. We feel this guarantee is clearly justified and easily fulfilled. If you have any questions regarding this unusual quality guarantee, please contact MicroCare directly.

Question 16

What is the Best nPB Replacement?

Accepted Answer

nPB is an abbreviation for “Normal Propyl Bromide” or “1-bromo-propane” indicated by the CAS #‎106-94-5 on Safety Data Sheets. This nonflammable fluid is a powerful cleaner with a low global warming potential. It is used as an alternative to CFC-113, methyl chloroform, hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs) in many critical cleaning, drying, carrier fluid and other high-value specialty uses where reliability is paramount.

Based upon toxicological research conducted by ACGIH, the Acceptable Exposure Limit (AEL) is 0.1 parts per million (ppm), using the 8-hour time weighted average (TWA) methodology. This means that nPB-based fluids should only be used safely in high-quality, tight, modern vapor degreasing equipment.

However, Governmental agencies in the the U.S., Canada and elsewhere around the world have been moving to restrict nPB use. Europe has already banned nPB for use as an industrial cleaner. Therefore, companies currently using nPB are proactively looking for a replacement for nPB.

Fortunately, there are a number of good nPB replacements available through MicroCare. These replacements for nPB are versatile, removing many types of contamination such as oils, grease and fluxes. They also feature the chemical physical properties (boiling point, flash point, specific gravity, viscosity, surface tension, etc.) that make the nPB replacements excellent cleaners but also easy to maintain, recycle and reuse.

In addition, the replacements for nPB are nonflammable, making them safer to ship, store and use. Some of the best nPB replacement fluids include:

Question 17

How do smoothing fluids work?

Accepted Answer

Today over 80% of 3D printed parts are made using thermoplastic or thermoset polymers. Metals, ceramics and other composite materials comprise the other 20%. Plastic 3DP parts are manufactured using any variety of 3D printing methods including FFF, DLP, SLA or material jetting processes. Common to all these methods is that the parts are created from a computer aided design (CAD) file and all are fabricated using a polymer construction material. The construction material is either powder-deposited or extruded through a nozzle in progressive layers, level-by-level, until the parts reach their final shape. The quality and the precision of the items made using 3DP processes result in parts requiring minimal post-processing and with excellent dimensional repeatability. However, building the parts is just the beginning of the 3DP process. Choosing the smoothing fluid also plays a key role in the successful construction of the 3DP components.

Fluid Finishing for Plastic Parts

The layered 3DP process leaves some plastic printed parts with a tiered or stepped surface, requiring smoothing to get a finished part. Traditional methods of smoothing the tiers, such as sandblasting, buffing or grinding, are manual, time-consuming, and often leave particles behind. A more efficient method for smoothing parts to their finished state is to use a specialty smoothing fluid inside a vapor degreaser to chemically even them out. Immersing the unfinished parts in a fast-evaporating fluid vapor inside the degreaser slightly melts the surface of the plastic parts, levelling out any irregularities and removing the tiers. It leaves a smooth finish without any leftover particles or damage to the finished parts. The quality of the finished parts is comparable in quality to parts using more traditional injection molding processes.

For smoothing to be effective, it is necessary to understand the chemical composition of the polymer parts. For instance, ABS, acrylic, polycarbonate and highly basic materials with a pH of 10 or above need to be approached carefully due to potential softening and swelling of the materials. Finding the best smoothing fluid can often be a delicate balance between selecting one with a high enough solvency to effectively level out the parts, but not so strong that it damages them or compromises their structural integrity. Trained vapor degreasing experts have experience selecting smoothing fluids for specific types of 3DP polymers and can guide part designers through this process.

In addition to smoothing the parts, the fluid must also be effective at removing soils or particulate left behind from any other manufacturing processes. The fluid, when used in a modern vapor degreaser can be used to dissolve and clean a variety of oils, greases and waxes. Any stray particulate like dust or shavings are typically non-soluble and will not dissolve in the cleaning fluid. Therefore, the particulate must be removed using displacement cleaning where the cleaning fluid gets under the particulate, dissipates any static charge and lifts it off the surface. The key to effective displacement cleaning is to use a dense, heavy fluid that floats the particles of dust and dirt off the substrate surfaces. Today’s modern fluids are typically 20% heavier than water and 50% heavier than alcohol, making them an ideal choice for displacement cleaning of 3DP polymer parts.

An added advantage of using a fluid for smoothing and cleaning 3D printed parts is that they dry very quickly and completely, leave no residue on parts and are cool after they exit the vapor degreaser. This allows parts to be packaged or post-processed immediately, speeding production and overall throughput.

In addition, modern-day 3DP post-processing fluids are nonflammable and safe for use in cold operations, heated machines or in ambient temperatures. They have also been formulated without the use of n-propyl bromide, methyl pyrrolidone, polyethylene glycol, heptane, or trichloroethane, all which can create groundwater and air quality issues.

Venesia Hurtubise is a Technical Project Chemist at MicroCare Corporation, which offers precision cleaning solutions. She has been in the industry more than 5 years and holds a MS in Green Chemistry from Imperial College, London. Hurtubise researches, develops and tests cleaning-related products that are used on a daily basis in precision cleaning and medical applications.

Question 18

How Do I Choose a Debinding Fluid for 3D Printed Metal Parts?

Accepted Answer

Metal 3D printing, a subset of additive manufacturing is a dynamic process used to make fully-finished, machine-grade metal parts. There are many types of metal 3D printing methods in use today. However, two-methods stand out for their speed, ease of use and cost-effectiveness.

Binder Jetting and Feedstock Extrusion both create parts either by building or extruding a combination of finely powdered metals and wax or plastic binders along a precise path, layer-by-layer directly onto a build plate. The binders serve a critical purpose to form the metal powder into a specific shape. However, the binders must be removed before the green parts can be exposed to the high heat required for the next step of sintering.

Used either in the liquid or vapor phase in a vapor degreaser, the debinder fluid selectively dissolves up to 4% of the binders and transports them out of the metal parts, creating pores and voids in the parts in preparation for sintering. The binders are progressively removed to avoid deformation and cracking during sintering, while also allowing the parts to maintain their dimensional accuracy, compress uniformly and sinter evenly.

This is where the physical properties of the debinding fluid become important and should be chosen carefully.

Question 19

Are Vapor Degreasing Solvents Flammable?

Accepted Answer

MicroCare recommends nonflammable solvents, or cleaning fluids, to minimize costs and maximize worker safety. In general, most of the the MicroCare, Tergo and Chemours Vertrel and Opteon products all are nonflammable. The full line of precision cleaning choices can be reviewed on this web site.

In terms of the hardware, most vapor degreasing systems are engineered for the use of nonflammable cleaning fluids. There are a few machines which can handle flammable fluids (for example, degreasing with alcohol) but these machines are very specialized and very expensive.

MicroCare does have some products which are flammable, such as the Swellex™ fluid, and some of the MicroCare benchtop PCB aersosol cleaners. These products, however, are not designed to be used as stand-alone products in vapor degreasers.

Question 20

What is Metal Additive Manufacturing?

Accepted Answer

Metal additive manufacturing, also known as metal 3D-printing is a process used to make fully-finished, machine-grade metal parts. It is a viable alternative to more conventional large-scale production methods such as subtractive manufacturing or injection molding, and in some instances is eliminating the need for machining altogether.

Ideal for producing parts with complex geometries, metal additive manufacturing can help maximize production by creating parts that would be too expensive or time-consuming to make using traditional machining methods like CNC, drilling or turning.

With metal additive manufacturing (AM), parts are manufactured using any variety of 3D printing methods including DMLS, SLM or binder jetting processes. Common to all these methods is that the parts are created from a computer aided design (CAD) file and all are fabricated using a metallic construction material. The construction material is either powder-deposited or extruded through a nozzle in progressive layers, level-by-level, until the parts reach their final shape.

In the metal additive manufacturing processes known as binder jetting, the construction material is a combination of fine metal powders and a binding agent. Metals available include stainless steel, tool steel, and many other ferrous and nonferrous alloys. Common types of binders contain paraffin wax, carnauba wax, and specialty polyethylene waxes.

The binders serve a critical purpose in forming the metal powder into a specific shape. However, they are ultimately sacrificial and must be selectively removed (up to 4%) before the green parts can be exposed to the high heat required for the next step of sintering.

Fluid extraction of the binders is easily done with a vapor degreaser. The debinding may be performed in either the vapor or liquid phase in the vapor degreaser depending on the metals used and the binders to be removed. Both vapor degreasing phases rely on the debinder fluid penetrating the parts to efficiently dissolve the wax from the parts interior.

The wax binders are progressively removed to avoid deformation and cracking during sintering while also allowing the parts to maintain their dimensional accuracy, compress uniformly and sinter evenly. Debinding is a balance of selectively eliminating some, but not all, of the binders in the shortest amount of time and with the least amount of damage to the parts structure since as the binders are removed, the parts become fragile.

Once the wax binders are fully removed from the green parts, the parts are ready to be sintered. Any remaining binders in the parts are effectively burned off while the parts are compacted at near melting temperatures. The metal powder bonds together and the finished parts reach their solid mass state. After that, the sintered parts can be post-processed using standard metal finishing techniques like grinding, sanding coating.

Question 21

How Does the Viscosity of a Solvent Affect My Cleaning Results?

Accepted Answer

Viscosity is a chemical characteristic that describes a fluids ability to flow quickly, smoothly and without outside effort. It is an indirect measure of the molecular attraction within a fluid for itself; highly viscous fluids are strongly attracted to their own molecules and resist separation.

In terms of critical cleaning, highly viscous fluids are not very good cleaners because they resist wetting the surface of the parts to be cleaned. Complex shapes and tiny parts are not well-wetted and therefore not well cleaned. In the table below, the viscosity of many popular solvents (and a few other benchmark fluids) are listed. Many MicroCare cleaning fluids have viscosity scores far, far lower than water or alcohol. As such, they will clean much better than those other fluids.

Viscosity is a key component in calculating the wetting index of a solvent. The higher the wetting index, the better the cleaner perorms.

Here is a list of solvents and their viscosity:

Fluid	Viscosity (cPs)
Air	0.02
Acetone*	0.30
AE-3000	0.34
Opteon™ SF80	0.42
Tergo™ XCF1 Specialty Cleaner	0.42
Genesolv® 2004†	0.43
Novec® 71DA	0.45
Solstice® PF	0.45
Tergo™ CCA Degreaser	0.33
n-Proply Bromide (nPB)	0.49
Tergo™ GCF	0.34
Trichloroethylene (“TCE” or “Trike”)	0.58
Tergo™ XCF2	0.42
AK-225	0.59
Methanol*	0.60
Tergo™ XCF3	0.57
Vertrel™ XF	0.67
Freon™ TF†	0.70
Perc or PCE	0.88
Water	1.00
Ethanol*	1.20
Mercury	1.50
IPA Alcohol*	2.40

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

Question 22

What's the Best Way to Store and Move Those Heavy Drums of Solvents?

Accepted Answer

MicroCare cleaning agents are shipped in bottles, pails and drums. The largest package, metal drums, can weigh in excess of 600 lb./280 kilos. Moving such heavy objects is a serious undertaking and not to be attempted without the proper equipment, training and supervision.

Full drums can be moved by forklift trucks and lifted onto racks to provide gravity feed to the point of use. Drum pumps are an even better idea and strongly recommended. Whenever drums are handled to transfer the cleaning agent, to empty drums, or to move them manually, several cautions should be observed:

Safety Precautions to Observe When Moving, Handling and Storing Solvents

Question 23

What Is Viscosity?

Accepted Answer

Fluid mechanics is the study of how fluids move, and one of the most important parameters of fluids is their viscosity. Most people think of “viscosity” in terms of a fluid’s ability to flow. Chemists have a slightly different feel for the phenomenon; viscosity is defined as its resistance to gradual deformation. This corresponds to the informal concept of “thickness” — for example, honey is thicker and has a much higher viscosity than water. Cleaning fluid viscocity plays an important role in how effective a cleaning fluid is.

According to Wikipedia, viscosity is the friction between the molecules of fluid. For example, when a fluid flows through a tube, the fluid will move more quickly near the center of the tube axis but move more slowly along the walls of the tube. This is because of the friction with the walls. Pressure or energy (“stress”) is needed to overcome the friction between the faster-moving fluid and the more slowly moving layers. Fluids with low viscosity have a low resistance and shear easily and the molecules flow quickly; high viscosity fluids move sluggishly and resist deformation. Some liquids, like pitch, glass and peanut butter, have such high viscosity they behave like solids.

In common vernacular, a liquid is said to be “viscous” if its viscosity is substantially greater than that of water, and is described as “mobile” if the viscosity is noticeably less than water. Viscosity varies with temperature and pressure. It is usually expressed, particularly in ASTM standards, as centipoise (cPs). For example, water at 20°C has a viscosity of 1.002 cPs.

When it comes to parts cleaning, low viscosity is a plus, especially in densely packed PCBs or small parts with complex shapes. Low viscosity cleaning fluids pentrate into these tight spaces, clean thoroughly and then easily evaporate, or dissipate without leaving contamination or residue behind. Here are some MicroCare cleaning fluids that are known for their low viscosity trait of 0.42 cPs or less.

Tergo™ XCF1 Cleaning Agent, Carrier Fluid & Particle Displacer
Tergo™ XCF2 Specialty Cleaning Fluid, Flux Remover and Degreaser
Tergo™ XCF3 Superior Cleaning Fluid and Degreaser
Tergo™ CCA Broad Range Degreasing Fluid
Opteon™ SF80 Specialty Cleaning Fluid

Some viscosities for other common fluids are listed in this chart for comparison:

Fluid	Viscosity (cPs)
Air	0.02
Acetone	0.3
Methanol	0.6
Water	1.0
Ethanol	1.2
Mercury	1.5
IPA	2.40
Olive oil	84.0
Motor Oil SAE 50	540.0
Maple Syrup	3,200.0
Honey	12,200.0
Molasses (treacle)	20,000.0
Peanut Butter	250,000.0

Cold molasses is a highly viscous liquid, as every grandmother knows.

Question 24

How Does the Boiling Point of a Solvent Affect Cleaning Results?

Accepted Answer

Many younger engineers today have never seen a vapor degreaser and are unfamiliar with the operations or the benefits of the technology. Because of its simplicity, vapor degreasing has proven to be the most consistent and “head-ache” free cleaning process. The “secret sauce” of vapor degreasing is the low-boiling solvent which makes the magic happen.

Let Thermodynamics Do the Cleaning

Most people are familiar with water cleaning. Water may be the elixir of life, but it’s not a great cleaning solvent because of the inherent limitations of the molecule. To overcome some of these natural limitations, aqueous cleaning processes tweak the systems in three dimensions: they extend the cleaning cycles, or extend the machines themselves with more pumps and sprays, or they add various soaps or saponifiers. All of this adds costs.

In contrast, vapor degreasing uses simple thermodynamics to clean, starting with low-boiling solvents or cleaning fluids. “Low boiling” is a relative term, in comparison to water. Modern Cleaning fluids boil from 15˚-70˚C (65°-170°F) depending upon the particular cleaning fluid. Many popular cleaning fluids boil almost at room temperature.

To begin, a low-boiling cleaning fluid is placed in the “boil sump” where the cleaning fluid is heated. Once boiling, the cleaning fluid produces a clear, dense vapor that is heavier than air, which rises through the machine gradually displacing the air in the degreaser. This is the “vapor blanket” and helps contain the liquid cleaning fluid inside the machine.

The boiling solvent in the degreaser gently cleans the parts without ultrasonics
The boiling cleaning fluid in the degreaser gently cleans the parts without ultrasonics

Eventually the vapors rise to the first set of refrigeration coils called the “primary condensing coils” (see photo). These coils chill the vapors and condense the cleaning fluid back into its liquid state. This condensed liquid drips into a trough that wraps around the internal circumference of the machine and is collected in the water separator (since some air-borne humidity from above the vapor blanket also condenses on these same coils) and eventually routed into the “rinse sump.” Since the rinse sump already is filled with clean cleaning fluid, the addition of more cleaning fluid causes the rinse sump to overflow, spilling the cleaning fluid into the same boil sump where it originally came from. This purging maintains a constantly clean rinse sump. It also concentrates any contamination into the boil sump, for easy removal and maintenance.

Benefits of Low-Temperature Cleaning

Because the cleaning fluids boil so easily, a number of important benefits become possible:

The cleaning system uses very little electricity, which saves money and helps prevent global warming
The system avoids dumping large quantities of humidity into the work environment, which water cleaning systems do continually
The vapors enhance the cleaning results, easily getting into tight spaces and under tiny stand-offs
The roiling, bubbling action of the boiling cleaning fluid “scrubs” the parts being cleaned very thoroughly but very gently, without ultrasonics
The low temperatures enhance worker safety
The cleaning systems are substantially smaller than aqueous cleaning systems, without the complex recycling/reverse osmosis filtration systems, which also save money

Here’s a general list of the boiling points of popular cleaning choices, sorted from lowest boiling temperature to highest:

Solvent or Ingredient	Boiling Point, ˚C
HFO-1233zd (“Solstice”)	15
HCFC-141b (“Genesolv”)†	32
HFC-365 (“Solvay”)	40
Methylene chloride	40
MicroCare HSFR	41
Methoxytridecafluoroheptene (“Sion”)	47
CFC-113 (“Freon”)†	48
Trans 1,2-Dichloroethylene*	48
HFC-43-10 (“Vertrel”)	55
Tergo™ Performance Fluids	55
HFE-7100 (“Novec”)	60
n-Propyl Bromide (nPB)	71
1,1,1 Trichloroethane (TCA)†	74
Carbon tetrachloride	77
Trichloroethylene (TCE)	>87
Perchloroethylene (Perc)	121

One final note: the boiling point does not affect the cleaning power of the cleaning fluid; that is a function of the Kb value and the viscosity, surface tension, densities, and low latent heat of the specific solvent. However, a higher-boiling cleaning fluid may be a useful tool when trying to remove insoluble contamination such as wax or buffing compounds because the solvent can melt the contamination and carry it away.

In short, an appropriate boiling point is the enabling trait that makes vapor degreasing so very useful. When the cleaning fluids are used in a properly configured cleaning machine, the results are consistent, affordable, fast, reliable, safe and environmentally acceptable.

Disclaimer

* Indicates a flammable cleaning fluid; this usually is an ingredient in an azeotropic blend.

† Indicates a Class 1 or Class 2 ozone-depleting solvent; no longer used by environmentally responsible companies and countries; included here merely for completeness.

Question 25

Do MicroCare Solvents 'Turn Acidic' Like Old-Style Cleaners?

Accepted Answer

That’s a great question. In general, modern solvents are neither acid nor alkaline, they are neutral.

However, old-style chlorinated solvents like 1,1,1, TCE, perc, nPB and methylene chloride could literally turn acidic (into hydrochloric acid) if the solvents were exposed to too much water and heat. This always was a mess.

When a system “went acid” the solvent had to be completely emptied from the machine and disposed as a hazardous waste. In addition, the entire vapor degreaser needed to be re-passivated and could be off-line for weeks or months for heavy maintenance.

Brominated solvents, such as nPB, also will degrade over time when catalyzed by water, certain metals, heat and oxygen. Degradation products include phosgene and bromic acid. These present worker safety concerns at elevated concentrations. Acidic solvent actually can destroy a vapor degreaser, requiring the solvent to be scrapped and potentially the entire machine to be rebuilt and repassivated. The use of stabilizers can avoid this disastrous situation.

To prevent systems from “turning acid” there are “acid acceptance” tests to measure the quantity of acid in the solvent. A simple calculation is all that is required to determine the amount of stabilizer that will be required to bring the system back into balance.

The replacement cleaning fluids for nPB from MicroCare are thermally and hydrolytically stable. The MicroCare, Tergo and Opteon fluids will not turn acidic except under the most extreme conditions, specifically (1) exposed to a strong base or acid, or (2) exposed to extreme heat, such as when the heater elements become exposed and “burn” the cleaning fluid. These fluids do not require the stabilizers or scavengers or testing required of nPB and TCE.

Question 26

Are MicroCare Cleaners SNAP Approved and Accepted?

Accepted Answer

Yes. All of the MicroCare, Tergo, Opteon and Vertrel brand products and their ingredients have been reviewed and accepted under the auspices of the Significant New Alternatives Program (SNAP) of the U.S. Environmental Protection Agency. A part of the implementation of the Montreal Protocol by the U.S. Government, the SNAP program is used by the EPA to ensure any new chemical introduced into the market by industry does not harm the stratospheric ozone layer. In recent years it has been expanded to include concerns about global warming, worker safety and smog.

In addition to SNAP approvals, all the MicroCare products also are TSCA approved (“Toxic Substances Control Act”), WHMIS approved for Canada, REACH registered for the EU, and ROHS and WEEE compliant. MicroCare produces and packages all these products in compliance with the Globally Harmonized System for chemical product safety and packaging.

These are great replacements for ozone-depleting solvents such as CFC-113, chlorinated solvents, HCFC-141b, HFE solvents and HCFC-225, as well as high-global-warming solvents such as perfluorocarbons (PFCs).

The “ozone hole” over Antarctica has shrunk by 4 million square kilometers from 2002-2015, mostly due to the reduction in ozone-depleting solvents. Source: BBC

Question 27

What Is the Meaning of a Fluid Toxicity Rating, Like a PEL or TLV?

Accepted Answer

In general, the “toxicity” of a cleaning fluid is measured through the use of 8-hour “time-weighted average exposure limits” (AEL). Similar terms you might find on labels and SDS sheets include “Average Exposure Limits” (AEL), “Personal Exposure Limits” (PEL) and “Threshold Exposure Limits” (TEL). One special term is “Threshold Limit Values” (TLVs) which only are established by the American Conference of Governmental Industrial Hygienists (ACGIH).

It is prudent to understand the underlying basis for exposure limits recommended or mandated by an organization or vendor. Some exposure limits are set simply to prevent acute effects such as eye or respiratory tract irritation that could make working uncomfortable or difficult to perform. Other exposure limits are set to prevent more serious immediate effects such as death by asphyxia (lack of oxygen). Most exposure limits are set to prevent long-term damage to organs of the body that could occur if high exposures continued over a period of time (days, weeks or even years). There are also exposure limits for shorter time periods and even “instantaneous” exposure limits which further quantify the risk of using a specific chemical.

These consensus values are considered protective of most (but not necessarily all) workers that would be exposed at the specified concentration for up to 8 hours per day, 40 hours per week, for a working life time (which is taken as 40 years). These ratings often are described as the “8-hour time-weighted exposure limit.”

In practical terms, a PEL defines the maximum safe concentration of a vapor in the air to which an employee could be safely exposed over the course of the workday. Note there could be periods of time spent working above the exposure limit as long as the average was below the PEL (that’s why it’s called a time-weighted average). Those periods would be offset by periods of time spent below the exposure limit. The result would be, that by the end of the workday, the average exposure would be 10 ppm or less.

There are other types of TLVs and PELs. For example, there are short-term exposure limit which are generally higher than the 8-hour TWA, there are acceptable daily limits, instantaneous exposure limits which must never be exceeded, and no-observed-adverse-effect levels. But the generally accepted standard for worker safety is the 8-hour TWA TLV.

One other bit of background: the “8-hour time-weighted exposure limit” is estimated to be one-tenth the minimum airborne concentration of vapors to which workers may be repeatedly exposed for an eight-hour workday over a hypothetical 40-year career without suffering any possible health effects. So a chemical with a 200 ppm TLV would typically have a 2,000 ppm no-observed-adverse-effect rating. All exposure limits are expressed in “parts per million” (ppm). For example, about 18% of the air we breathe is pure oxygen. This means that oxygen is present in the atmosphere at 180,000 parts per million.

Question 28

What Is the Truth About the Toxicity of nPB?

Accepted Answer

The brominated molecule known as nPB (also called n-Propyl Bromide, 1-Bromopropane or CAS # 106-94-6) is a nonflammable fluid. It is a powerful cleaner with a low global warming potential. It is used as an alternative to CFC-113, methyl chloroform, hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs) in many critical cleaning, drying, carrier fluid and other high-value specialty uses where reliability is paramount.

Based upon toxicological research, the ACGIH set the Acceptable Exposure Limit (AEL) is 0.1 parts per million (ppm), using the 8-hour time weighted average (TWA) methodology. This means ANY nPB product cannot be safely used in an uncontrolled environment, such as an aerosol dispenser. nPB used in vapor degreasing is also under scrutiny by many governmental agencies.

The Hazards Associated with nPB

In simple terms, the hazards associated with n-propyl bromide can be viewed with regards to short and long term exposure. Early on, the U.S. National Toxicology Program recommended a No Observable Adverse Effect Level (NOAEL) for nPB of 100 ppm, which, with a sensible ten-fold safety factor, led to a 10 ppm (parts per million) exposure limit recommendation.

But more recent research suggests there are significant toxicity worries. From a long-term viewpoint, tests in animals have shown long-term overexposure to nPB may lead to multiple adverse affects in the body likely including fertility problems for both males and females. Recent health studies have found nPB damages the nervous system, alters human DNA, impairs fertility and there is a risk of cancer.

Based on these reports, the European Chemicals Agency (ECHA) listed nPB as a ‘Substance of Very High Concern’ in December 2012 and nPB was bannedas an industrial cleaner in Europe in 2020.

The government of Ontario, Canada also has become concerned about the long-term toxicity of nPB. In July 2017 the Ministry of Labour enacted new worker-safety rules which restrict the deployment of this widely-used chemical. Today the aceptbale exposure limit is 0.1 ppm.

In the US, several government agencies originally recommended 10 ppm as the proper exposure limit. Separately, California adopted a 5 ppm limit and an independent safety agency, the American Conference of Governmental Industrial Hygienists (ACGIH), lowered their recommended exposure rating to just 0.1 ppm in 2014.

A Ban on nPB is Certain

Today, nPB is under scrutiny by the U.S. EPA (Environmental Protection Agency), OSHA (Occupational Health and Safety Administration). In 2018, the EPA added nPB to its TOSCA (Toxic Substance Control Act) list. In August, 2020 the EPA reported that nPB presents unreasonable risk to human health and should be restricted as a cleaner or degreaser.

This report is just a preliminary step for the EPA. It will likely lead to a complete EPA ban on nPB by 2023. nPB is already sunset or banned in Europe as of July 2020. And many other countries are likely to follow and ban the use of nPB in the near future.

MicroCare offers a variety of good substitutes for n-Propyl Bromide. These high-purity, non-flammable, sustainable vapor degreaser fluids provide superb cleaning on both polar and non-polar soils.

These fluids have low viscosity and surface tension. This allows the fluids to permeate tight crevices and wet all the surfaces of the parts. They are also are high solvency (with high Kb Values) which allows them to rigorously clean surfaces and displace tough soils, yet not damage delicate materials.

Tergo™ Metal Cleaning Fluid An environmentally sustainable azeotropic cleaner engineered for fast, consistent and economical cleaning in vapor degreasers

Tergo™ Chlorine-Free Cleaning Fluid This High-temperature, high strength degreaser removes stubborn soils

Tergo ™High Performance Flux Remover Sustainable Tergo™ HPFR High Performance Flux Remover excels at removing stubborn white residue and difficult no-clean fluxes

Opteon™ SF80 Cleaning Fluid Opteon™ SF80 combines the high solvency needs for industrial cleaning with and environmentally-friendly low GWP (Global Warming Potential)

Other custom formulations and pending prototype currently in development may also be available.

Question 29

Are There Different Solvent Grades of Purity?

Accepted Answer

Yes, there are. MicroCare can make many different grades of our cleaners to satisfy the client’s requirements for purity. For example, several products, such as Vertrel™ XF have a super-pure grades for the semiconductor, LCD and disk drive industries. This means the accuracy of the blending, the nonvolatile residues and water content are all exactly where you want them, and this information is included on the Product Specs.

Not only is the solvent cleaner, the packaging is cleaner. Usually high-purity materials are packaged in glass gallon containers, double filtered to 0.2 microns, and has tighter specifications for additional types of contamination than the standard product. These products will carry a special name, a special part number and a special price.

Question 30

Is a Bi-Solvent Cleaning System a Good Option for Critical Cleaning?

Accepted Answer

In the world of vapor degreasing, there are three types of solvent degreasing systems: mono-solvent cleaning, co-solvent cleaning and bi-solvent cleaning. Here we take a deep dive into the bi-solvent cleaning process:

In general, the MicroCare mono-solvent cleaning fluids can perform all of the required cleaning jobs. But once in a while a customer has a particular contamination that can’t be managed by a single solvent cleaning process. This can happen because of specific types of contaminants, materials compatibility issues, throughput issues or maybe environmental regulations.

A co-solvent cleaning fluid system might fix the problem by adding a strong, non-volatile solvating agent to the boil sump of the degreaser. But this can be limited by the temperature of the rinsing fluid. If the rinsing fluid boils at 40˚C, and the contamination needs to reach 100˚C to be cleaned, no amount of co-solvent scrubbing is going to get the job done.

Therefore, once in a great while, customers need a second machine which operates at much higher temperatures. This will deliver approximately the same convenience and speed of traditional mono-solvent cleaning, but amplified by the second solvent and much higher temperatures. This bi-solvent process provides the additional muscle or horsepower that the application requires.

How Does It Work?

The two solvents have very different behaviors. The solvating agent of the bi-solvent cleaning system (Solvent B) is located outside the degreaser in a separate cleaning tank. It operates at much higher temperatures than the rinse agent.

The rinse agent (Solvent A) inside the vapor degreaser (typically an HFC, HFE or HFO based rinsing agent) boils at a lower temperature (like the MicroCare™ and Vertrel™ solvents). They both rinse the bi-solvent from the parts and also rinse any lifted or loosened contamination from the parts.

The bisolvent fluid is collected in the distillation phase of the rinse degreaser and usually can be recycled and re-used, which saves money.

The bi-solvent system delivers excellent cleaning on all types of solder fluxes, oils, greases, waxes, and particulates, paints, buffing compounds and anti-rust agents. It is highly compatible with most metals and ceramics. It also has broad compatibility with plastics and elastomers that can withstand the boiling temperatures. Bi-solvent cleaning delivers excellent cleaning without water or other problematic cleaning products.

In summary, a bi-solvent cleaning system should be used only for the most difficult soils, which often require high temperatures for removal. In the right application they can provide superior cleaning results without the throughput delays inherent in aqueous systems.

Question 31

What Are the Benefits of Azeotropes for Precision Cleaning?

Accepted Answer

Azeotropes are way cool. Azeotropic behavior allows clever engineers to deliver the benefits of a mixture with the convenient handling and storage of a single compound. Perhaps one chemical is nonflammable but not a great cleaner. But mix it with a super cleaner that happens to be flammable and what happens? You get a great nonflammable cleaner. It’s like getting two different solvents out of one drum. Learn more about azeotropes here.

First, azeotropes are very easy to distill and recover. Azeotropes can be repurified while the contamination — fluxes, oils, water, belly-button lint and such — stay “trapped” in the liquid at the bottom of the machine. In effect, using azeotropic solvents allows us to trap and concentrate the contamination by distillation instead of using filters and membranes and such.

Another important benefit of an azeotrope is the unexpected ability to mix flammable and nonflammable ingredients to produce a stable nonflammable mixture. This is an amazing chemical phenomenon. Imagine mixing flammable products — like alcohol — into a nonflammable solvent and yet still be retain the convenient and safe handling characteristics of a nonflammable chemical. This is a big boost for safety!

Lastly, azeotropes permit the “tweaking” or customizing of a solvent to obtain unique physical properties which makes the blends useful across a broad range of applications. For example, nPB is a very aggressive cleaner. But add some other ingredients in azeotropic proportions, and MicroCare can make a product that is milder and easier to handle. The possibilities are almost limitless.

A Quick Summary of the Benefits of Azeotropic Cleaning

Easy Operations: Manufacturing personnel deal with one solvent instead of multiple fluids. A single azeotropic solvent eliminates the need to monitor the ratio of solvating agent and rinse agent.

Simple Management: Monitoring the contamination level in an azeotropic solvent is much easier than determining the soil level in, say, an aqueous system. Most manufacturing companies do not have the laboratory capability to determine the soil level in the solvating agent so they prematurely discard cleaning fluids, to preserve quality production. This can be expensive.

Higher Soil-Loading Capability: Azeotropic solvents can have higher soil-loading capability, which allows the solvent to be used longer and thus reduces solvent costs.

Faster Cleaning: Because they can be tailored to the contamination, azeotropic solvents can clean much faster than some monosolvents. This can reduce the cleaning cycle time by as much as 75%, increase productivity, and eliminate production bottlenecks involving the cleaning operation.

Safety: First and foremost, azeotropes for vapor degreasers are nonflammable. This makes cleaning processes simpler, safer and more reliable by an order of magnitude.

Save Money: Both solvent and energy costs are lower with azeotropic solvent systems, and capital costs are low, too, because azeotropes can be used in standard, off-the-shelf commercially available degreasers. Azeotropic solvents are normally less expensive than the combined costs of two solvents used in a co-solvent process or than aqueous cleaners.

The chemical experts in the MicroCare Cleaning Lab are highly proficient at formulating and producing azeotropes using unorthodox ingredingredients, which helps MicroCare customers save money. No other vendor has this capability combined with the depth of expertise. Here are some of the azeotrope cleaning fluids that MicroCare offers.

Tergo™ XCF3 Superior Cleaning Fluid and Degreaser
Tergo™ CCA Braod Range Degreasing Fluid
Tergo™ PF105 High Purity & Ionic Static Remover
Tergo™ PF100-IPA IPA Based High Purity & Ionic Static Remover

Question 32

What's an Azeotrope and Why Should I Care?

Accepted Answer

Many of the MicroCare cleaning fluids technically are called “azeotropes.” That’s important because azeotropic cleaning lowers your costs, boosts cleaning effectiveness and enhances worker safety. While azeotropes are difficult to make, these strong benefits make the effort worthwhile.

So the next question you’re going to ask is, what’s an azeotrope and how does an azeotrope do all those good things? For the answer, we have to go back to Chemistry 101.

Azeotropes Defined

First, an azeotrope is best described as “a constant boiling blend.” To be an azeotrope, the liquid has to be a mixture of at least two different elements or compounds. For example, “neat” HFC-43-10 and “neat” nPB are not azeotropes because there’s nothing else in it but one type of molecule. This is called a “monosolvent.”

Now, oil and vinegar are a mixture of two fluids, but they’re don’t make an azeotrope because the fluids separate from each other, almost instantly. Same with oil and water.

But MicroCare CMS, which is a mixture of two HFC fluids and a third chemical called “trans.” Lots of chemicals mixed together, but they behave as though they were one chemical.

A basket of PCBs being raised out of the solvent in the rinse sump on a vapor degreaser

Consider the boiling point of these materials.

The boiling point of nPB is about 70° C/170° F. But mix nPB with a small but precise amount of alcohol and the boiling temperature suddenly drops. This is very odd and unexpected. The two chemicals are still separate and distinct in the mixture; there has been no chemical reaction in which they actually change their chemical state. But somehow the two chemicals are working together to lower their combined boiling point. Most importantly, when we boil this mixture the two constituents boil off at the same rate.

Let’s suppose the mixture we are testing is 97% nPB and 3% alcohol. If we measure the fumes coming off the boiling liquid, we would be pleased to notice that the mixture of the ingredients in the fumes also was at the same 97:3 mixture. When we chill those vapors and distill the material, it again will have the same 97:3 mixture. In fact, no matter what we do the mixture it always stays at the 97:3 proportions. This means we have created an azeotrope.

There is a bit of magic to making azeotropes. Not all liquids form azeotropes because the density, boiling point and surface tension all has to be exactly right.

Why Do I Care?

Azeotropes are way cool. Azeotropic behavior allows clever engineers to deliver the benefits of a mixture with the convenient handling and storage of a single compound. Perhaps one chemical is nonflammable but not a great cleaner. But mix it with a super cleaner that happens to be flammable and what happens? You get a great nonflammable cleaner. It’s like getting two different solvents out of one drum.

For example, azeotropes are very easy to distill and recover. If the solvent in a vapor degreaser acts as an azeotrope then the solvent can be boiled away and distilled while the contamination — fluxes, oils, water, belly-button lint and such — stay “trapped” in the liquid at the bottom of the machine. In effect, using azeotropic solvents allows us to trap and concentrate the contamination by distillation instead of using filters and membranes and such.

Another important benefit of an azeotrope is the unexpected ability to mix flammable and nonflammable ingredients to produce a stable nonflammable mixture. This is an amazing chemical phenomenon. Imagine mixing flammable products — like alcohol — into Bromothane™ R and yet still be retain the convenient and safe handling characteristics of a nonflammable chemical. This is a big boost for safety!

Lastly, azeotropes permit the “tweaking” of a blend to obtain unique physical properties which makes the blends useful across a broad range of applications. For example, HFC-43-10 is a very mild cleaner. But add some other ingredients in azeotropic proportions, and we can make it into a blend that is much stronger and more effective. This allows us to “tailor” a cleaning fluid for your exact contamination. The possibilities are almost limitless.

Only MicroCare has the broad range of ingredients and expertise to engineer money-saving azeotropes for your applications. Look for the term “azeotrope” in the product description and in the SDS sheet.

Question 33

Is Co-Solvent Cleaning in a Vapor Degreaser a Good Option?

Accepted Answer

Most companies do not need the extra cleaning horsepower provided by co-solvent cleaning systems. However, for special applications it is a very smart and sophisticated option.

In general, the MicroCare monosolvent fluids can perform all of the required cleaning jobs. The problem arises when you can’t get the cleaning horsepower you need from a monosolvent system. This can happen because of contamination types, materials compatibility issues, throughput issues or maybe environmental regulations. In this case, you are going to need to add some cleaning power.

A co-solvent system delivers the convenience and speed of traditional monosolvent cleaning, but amplifies this cleaning with a second component or set of components. This second portion (Solvent B) provides the additional muscle or horsepower that the application requires.

The two solvents have very different and distinct behaviors. The primary difference between the two solvents will be their boiling points: one boils at a low temperature (Solvent A) and the other (Solvent B) boils at a much higher temperature. They work together to supplement, enhance or boost overall cleaning performance.

The low-boiling solvent (Solvent A) is referred to as the rinsing agent and is formulated based on HFC, HFE or HFO fluids. The rinsing agent washes the solvating agent (Solvent B) off the components and provides the vapor blanket for the system.

The Tergo™ Chlorine-Free Cleaning Fluid is the MicroCare co-solvent cleaning product, engineered for maximum environmental protection. It is a two-part, nonflammable, non-chlorinated, multi-functional cleaning fluid engineered for use in vapor degreasers and is referred to as a “co-solvent system.” The solvating additive is a proprietary, non-volatile, high-boiling point mixture. The rinsing agent is a low-boiling hydrofluoroethers-based (HFE) solvent blend. Together, the system delivers excellent cleaning on all types of solder fluxes, oils, greases, waxes, and particulates, paints, buffing compounds and anti-rust agents. It is highly compatible with most metals, plastics and ceramics; it also has and broad compatibility with plastics and elastomers.

Many co-solvents may be able to be used inside existing two-sump vapor degreasers, however, it’s best to consult with one of our MicroCare applications specialists to determine if this will be the case in your particular application.

In summary, a co-solvent system should be used only for difficult soils, which often require high temperatures for removal. In the right application they can provide superior cleaning results without the throughput delays inherent in aqueous systems.

Question 34

Which Solvent Is Best to Remove Insoluble Particulate?

Accepted Answer

This is another application where MicroCare cleaners really shine. “Particulate removal” processes are generally called displacement cleaning.

The unique circumstances of this application are found in instances when the contamination is not soluble in any solvent. This happens more often than you might think: solder balls, metal finings, dust and grit all are examples of contamination which are not soluble in anything.

They key is using a dense solvent. Dense, heavy solvents clean better than light solvents. The density of alcohol is about .78 (kilos per liter); and 1.0 is the density of water. Many MicroCare solvents are 30-40% heavier than those choices. This gives modern solvents the ability to float particulate off of surfaces. Just as a boat floats in the ocean, a dense solvent will float particles of metal, lint, dust and fibers from a substrate.

To compound the difficulties, often the particulate is tightly linked on to a substrate with a tiny static charge. At the microscopic scale of these particulate, even faint ionic bonds are very strong when compared to the mass of the contamination. The strength of these bonds makes it almost impossible to remove this contamination.

For these applications, a conductive solvent with a high density and a high wetting index is a great choice. Examples might be Tergo™ XCF2 Specialty Cleaning Fluid, Opteon SF80, and Tergo GCF (General Cleaning Fluid). All are highly polar, extremely dense and can actually float the contamination away in a manner that aqueous cleaners simply cannot match.

Question 35

Is Personal Protective Equipment Required When Working with Solvents?

Accepted Answer

Safety first is the prime directive at MicroCare. As such, MicroCare Applications Experts can help you understand how to properly and safely use solvents and cleaning fluids. A MicroCare representative can inspect your facility and your system to ensure that it is working properly; teach your employees about the solvent and present the proper methods for handling and storing the chemicals. So when it comes to safety, MicroCare offers a number of excellent answers. Here are a few general tips for operators:

Skin and Eye Contact:

Eye and skin protection is STRONGLY recommended; see photo.

Common sense strongly recommends that prolonged or repetitive skin contact with any solvent or chemical should be avoided. These solvents remove natural oils from skin, and are particularly adept at dissolving natural oils. This can result in the temporary drying, itching, swelling and roughening of the skin. This temporary irritation of sensitive skin is called temporary local dermatitis. Healing is rapid after the exposure ceases. Impervious gloves and protective clothing really are the best choice if there is any potential for skin contact. Gloves, splash goggles, aprons (when handling open drums), and safety shoes with steel toes are highly recommended.

In terms of gloves, MicroCare recommends gloves made of butyl rubber or other materials to provide optimal protection. In some applications a more durable two-part glove might be necessary. Choose the powderless option if it is important to control nonvolatile residue in your production process. These are widely available from quality distributors everywhere.

Just for the record, we practice what we preach. The staff at MicroCare are expert at moving, blending, handling and storing chemicals. Nonetheless, despite our expertise and familiarity with these chemistries, everybody at MicroCare always wears eye protection and protective clothing in the manufacturing area. If we wear them, your people should wear them, too. It just makes sense.

Inhalation:

Use with adequate ventilation. Avoid product misuse; deliberate inhalation can produce intoxication and be fatal. Vapors are six to eight times heavier than air. Vapors tend to accumulate in low places. Inhalation of concentrated vapors can cause suffocation. Provide forced air ventilation when entering tanks or confined areas. High concentrations of vapors in confined spaces can be fatal due to lack of oxygen. Over-exposures may cause tremors or convulsions. Use exposure monitoring badges to help track and manage worker exposures.

Spill/Leak Management:

In the event of a spill or leak, remove all possible ignition sources and provide ventilation in the event of a spill. Avoid contact with open flames or hot surfaces because the products may produce toxic decomposition products. The smell of the toxic decomposition products serves as a warning agent.

There are a number of accesories which can be added to vapor degreasers to improve cleaning performance and lower costs, including automated hoists (shown here), superheat, and ultrasonics in the rinse tank.

Question 36

What's the Proper Disposal Process for MicroCare Solvents? Can They Be Recycled?

Accepted Answer

When disposing of MicroCare solvents, remember the solvents never wear out. Inside a vapor degreaser the solvent is automatically recycled, and can be used for hundreds or even thousands of cleaning operations. This is a major difference from aqueous cleaning, where the soaps and saponifiers are used only once.

Some locations now are offering a recycling service, which takes back your spent solvent and returns “reclaimed” solvent, similar to the service which was widely offered for CFC-113, HCFC-141b and other major solvents. MicroCare has a list of names of companies offering this service; contact MicroCare to see if there is a company in your area.

As for disposal, the fluids are generally shipped as “Non-Regulated/Non-Hazardous.” This would apply unless the user has introduced a RCRA hazardous material during use. Users should test the exhausted product to ensure proper RCRA classification for waste disposal and should check local, state, and federal requirements in determining disposition of spent product. Most spent solvent is incinerated in cement kilns; typically that service costs $150 per drum. Contact your hazmat disposal service for details; normally they will require a chemical analysis of the material to determine the exact chipping classification.

(Special note for visitors from outside the USA: “RCRA” is a U.S. hazmat handling law and obviously only applies within the USA. For the rules in other countries contact your local hazmat disposal service.)

Question 37

How Do I Ship MicroCare Solvents and Keep Freight Costs Low?

Accepted Answer

MicroCare cleaning fluids are easy to ship and store, even when shipping by air, which saves companies lots of money. Because MicroCare, Tergo, Vertrel and Opteon vapor degreasing cleaning agents all are nonflammable and non-corrosive, they are not regulated as “dangerous goods” or hazardous materials within the US or internationally. Even though some cleaning agents are mixtures that include other solvents such as alcohol, none of the mixtures are classified as flammable, poisonous or corrosive. They all ship under the classification of “Non-Regulated/Non-Hazardous.” Additionally, insurance companies don’t find any risks or threats from storing nonflammable solvents, so there is a potential savings in insurance costs. See the Safety Data Sheet for more details about shipping, storage and handling.

Question 38

What Are the Benefits of Using a Vapor Degreaser? How Does It Save Me Money?

Accepted Answer

Vapor degreasers are cleaning machines which easily and quickly can clean metal, ceramic, glass or plastic parts. They are widely used in electronics, precision metal finishing, medical device manufacturing, aerospace and so on.

The concept behind vapor degreasing is very simple. The parts are cleaned and rinsed in the cleaning fluid. But, while the cleaning is occurring, the cleaning fluid is boiled into a vapor (steam). The system them contains the vapors, cools those vapors back into a liquid, and collects this purified liquid for continuous use. Here’s the punchline: a vapor degreaser not only is a cleaning system but a continuous recycling system, which means they deliver extremely cost-effective critical cleaning.

Why do companies prefer vapor degreasing for their automated cleaning?

The benefits of a vapor degreaser include:

Highly Effective Cleaning: Vapor degreasers and their solvents can easily clean almost every type of contamination, up to and including heavy greases, oils and even waxes.
Versatile Cleaning: Vapor degreasers and their special solvents can easily get into and around parts which are extremely small or have extremely tight clearances, delivering perfectly clean shapes and parts
Speedy Cleaning: Vapor degreasers have very short cleaning cycles, so even a modest batch machine can usually outperform an in-line water cleaning system costing two or three times the price.
No Entrapment: Because the solvents evaporate so quickly, the vapors are easily removed from complex shapes, deep holes, blind vias and other designs where slow-drying solvents either could not clean or could be trapped. This keeps costs down and quality up.
No Water Spots: Water often leaves unacceptable water spots which vapor degreasers never leave, making them perfect for cleaning optics and other super-critical applications.
Broad Materials Compatibility: Solvents and vapor degreasers are highly suitable for use with most components because there are no high pressure sprays, the temperatures are low and the cleaning cycles brief.
Planet-friendly Cleaning: Vapor degreasers use tiny amounts of electricity and no water, so they are very gentle on the environment.
Lowest Cost-Per-Part-Cleaned: Vapor degreasers are very inexpensive to purchase and use. A modern degreaser can limit solvent consumption to pennies or dollars per day.

If, at any time, there are questions about these products, their use or the results obtained, please contact MicroCare immediately for fast, accurate and up-to-date information on these products.

Spot-free cleaning without water is an important benefit of modern solvent cleaning in a vapor degreaser

Question 39

Do MicroCare Cleaners Contribute to Global Warming?

Accepted Answer

Some of the MicroCare cleaners have significant global warming potential (“GWP ratings”). These include some of the products containing HFC fluids and, to a lesser degree, the HFE fluids. Products containing HFO solvents and nPB fluids do not contribute to the problem of global warming.

First, a word of explanation. Global Warming Potential (G.W.P.) is an attempt to predict the effect a stable, long-lived molecule might have in warming the atmosphere of the planet. It is thought that the gradual warming of the atmosphere could have catastrophic environmental effects, increasing the deserts of the world, devastating crop lands, and causing wide-spread extinctions of many species. Perfluorocarbons (PFCs) and sulfur hexafluoride (SF6) are the main High Global Warming Potential gases. Many of these gases are 1000, 10,000 even 20,000 times more powerful than the baseline carbon dioxide (CO2). They also have very long atmospheric lives and many can stay in our atmosphere for thousands of years.

Many, many common chemicals have GWP ratings. The GWP of the HFC solvents are about 1,000, depending upon the exact formulation. The big contributors here are refrigerants used in air conditioning and refrigeration, exceeding the contributions of cleaning solvents by thousands of times.

Another environmental concern is low-altitude smog. Smog is generally caused by Volatile Organic Compounds which react with sunlight. This is where things get sticky.

In general, chemicals that have high GWP ratings have low VOC ratings. High VOC ratings generally mean a chemical has a low GWP. It’s like a child’s teeter-totter: one when side goes up, the other side must go down. It is almost impossible for a chemical to be both a low VOC and a low GWP, and the few cleaners that do manage this trick usually are flammable.

Environmental Recommendations

First, if you can, select an HFO or nPB based cleaning fluid because these solvents get very good scores on the global warming scale. The HFOs have GWP of less than 10 and usually 1, which is about as good as you can get. NPB usually is rated with GWP scores of zero, due to the very short atmospheric lifetime of the material.

In short, MicroCare has a whole family of highly effective, planet-friendly replacements for high GWP solvents such as CFC-113, 1,1,1-trichloroethane, HCFC-141b and HCFC-225, as well as high-global-warming solvents such as perfluorocarbons (PFCs).

A computer-generated map of temperature anomalies around the globe in 2015. Source: GISS

Question 40

Are MicroCare Critical Cleaning Fluids Ozone-Safe?

Accepted Answer

Yes. All of the MicroCare cleaners are 100% completely ozone-safe. None of the HFC, HFE or HFO cleaning fluids sold by MicroCare contain any ozone-depleting substances. Here are the details:

The Montreal Protocol, the Benchmark in International Co-operation

In the 1980’s a group of experts were tabulating all of the world’s ozone-depleting solvents and classified them into three groups: Class I ozone-depleters were the really bad actors, the Class II materials had an impact but to a much, much lesser degree; and the products that were completely ozone-safe. The lists of Class I and Class II products became the heart of the Montreal Protocol, the first international treaty to protect the ozone layer.

But nPB-based cleaners never made it on to the list. This is because at the time nobody was using nPB as a solvent. It just fell through the cracks.

So while it may sound like some people are splitting hairs, it is technically correct to say that nPB is not listed in the Montreal Protocol as an ozone-depleting solvent (“O.D.S.”) and it is not a “Class II” ozone-depleting material.

But the more precise truth is to report that while nPB is not a Class II O.D.S., it does have a slight ozone-depletion potential. The exact ozone impact is still under assessment from the U.S. Environmental Protection Agency, but many companies judge that 0.0006 is a reasonable estimate. This compares to 0.13 for HCFC-141b and 1.13 for CFC solvents. It’s a big step in the right direction.

Ozone-Depleters Today

MicroCare precision cleaning fluids are ideal replacements for the listed ozone-depleting solvents in precision cleaning applications. They are “drop-in” replacements for old-style solvents such as CFC-113, 1,1,1-trichloroethane, HCFC-141b and HCFC-225, as well as high-global-warming solvents such as perfluorocarbons (PFCs).

The “ozone hole” over Antarctica has shrunk by 4 million square kilometers from 2002-2015, mostly due to the reduction in ozone-depleting solvents. Source: BCC

Question 41

Do MicroCare Vapor Degreaser Cleaners Contain Volatile Organic Compounds (VOCs)?

Accepted Answer

Volatile Organic Compounds (VOCs) are a source of worry because they contribute to low-altitude smog in cities. Obviously, the most common VOC is gasoline, but that is not a regulated solvent so the VOC question never comes up. However, in some regions such as Southern California the government is regulating VOC content in many products, including windshield wiper fluids and barbecue starter fluid.

In general, many of the MicroCare™, Vertrel™ and Tergo™ cleaners contain some levels of VOCs and are photoreactive. This may make them an unacceptable choice in some communities with rigid VOC regulations. Check the Product Specification for more details on the product you are considering as a cleaning fluid.

However, it’s important to realize that many, many common chemicals have a high VOC content. In general, chemicals that have high VOC ratings do not contribute to global warming. Low VOC ratings generally mean a chemical is likely to have a high GWP. It’s like a child’s teeter-totter: one when side goes up, the other side must go down. It is almost impossible for a solvent to be both low in VOC content and low in GWP. The few cleaners that do accomplish this magic trick usually are flammable and would not be suited for vapor degreaser operations.

The burning of organic materials, such as gasoline or coal, produces smog over cities around the world. While solvents are a tiny part of this very big problem, the use of low VOC solvents makes a difference. Photo: smog over Mexico City.

The table below lists the organic content for the industries most popular cleaning choices, almost all of which are available from MicroCare:

Not-In-Kind Benchmarks

Brand Name or Description	Principle Supplier	Base Chemistry	Organic Content
Water		H20	0
IPA Alcohol*		Alcohol	790

First Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Organic Content
Trichloroethylene (TCE or Trike)		Chlorine	1460
Perchloroethylene (PCE or Perc)		Chlorine	1620
Freon™ TF†	DuPont	CFC-113	0

Second Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Organic Content
Genesolv® 2004†	Allied-Signal	HCFC-141b	47
AK-225†	Asahi	HCFC-225	0
Bromothane™ (nPB)	MicroCare	Bromine	1350

Third Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Organic Content
Novec® 71DA	3M	HFE-7100	n/a
Vertrel™ XF	Chemours	HFC-43-10	Exempt
MicroCare™ HDS	MicroCare	HFC-365	500
Vertrel™ SFR	Chemours	Trans	1063

Fourth Generation

Brand Name or Description	Principle Supplier	Base Chemistry	Organic Content
Opteon™ Sion/SF79	Chemours	MPHE	278
Solstice® PF	Honeywell	HFO-1233zd	Exempt
AE-3000	Asahi	HFE-347pc-f	0

For the specific details for each product, see the individual Product Specifications available on this web site.

Disclaimer

“n/a” indicated the rating is not available.

“Exempt” indicates the product has such a short atmospheric life that it is not considered a significant contributor to low-altitude smog.

* Indicates a flammable liquid unsuitable for vapor degreasing but is included here just for completeness and ease of comparison.

† Indicates a Class 1 or Class 2 ozone-depleting substance no longer on the market; included here just for ease of comparison.

Question 42

Are MicroCare Vapor Degreaser Cleaners F.D.A. Approved?

Accepted Answer

No, the MicroCare vapor degreaser cleaners are not approved by the U.S. Food and Drug Administration. However, It is perfectly acceptable to use these medical cleaners on medical products for cleaning and surface preparation. This is because the solvents evaporate completely and leave no residues. There is nothing which stays on the surface of a product to be ingested or retained by the body.

However, should some customer wish to use one of these cleaners in some sort of implanted medical application, they should be aware they will be responsible to obtain all of the required approvals from the F.D.A.

Question 43

Are MicroCare Precision Cleaners Mil-Spec Approved?

Accepted Answer

No, the products are not “mil-spec approved” because old-style “military specifications” no longer are used. But that doesn’t mean the military, NATO, or military suppliers aren’t using the MicroCare solvents.

The Evolution of Cleaning Specifications

In the old days, say the 1960s, when governments decided they needed a new jet, missile or submarine the military would define every aspect of the manufacturing of that system. These specifications included the types of solvents which were acceptable to use when cleaning the components. For electronics, the most popular specification was WS-6538 and the most popular solvent was Freon, which is the solvent CFC-113. It was a big ozone-depleter and was banned in the 1980s.

In the 1990s the military, in conjunction with the I.P.C., developed MIL-STD-2000 as the first of the performance-based cleaning specifications. In effect, MIL-STD-2000 allowed the manufacturer to use any solvent they wanted, provided they could prove the new cleaning method was at least as good as the old cleaning method. One good benchmark was to switch from Freon to Genesolv 2004, which was less harmful to the ozone-layer. Customers would perform before-and-after benchmark tests and compare the results. If the cleaner worked well they were free to use newer, more environmentally-friendly cleaners.

Today, even MIL-STD-2000 has been rendered obsolete by more sophisticated “performance based” standards and “SNAP” approvals from the E.P.A. in the USA. In the place of the old specs, many military manufacturers have adopted MicroCare cleaners because they deliver fast, consistent and affordable critical cleaning that meets or exceeds the requirements of the old military standards.

These two bearing are part of a military helicopter, and they are being degreased in a MicroCare cleaner during depot maintenance

Question 44

What Is “Critical Cleaning”?

Accepted Answer

MicroCare divides the cleaning world into two big segments: critical cleaning, and everything-else, “good enough” cleaning.

In the category of “everything else” is hygienic cleaning in restaurants and hospitals; industrial degreasing of metal parts, or commercial cleaning such as transportation systems. Think of a brake cleaner used in an auto repair shop, the cleaning performed in a restaurant, or a big industrial degreaser found in a machine shop. These are industrial cleaning applications. If the cleaning is not perfect, no harm generally happens. “Good enough” rules.

But suppose you are cleaning parts for the Space Station. Or a heart pacemaker. Or the autopilot for a jetliner. Or a firefighter’s emergency radio. In these instances, if the cleaning isn’t perfect, the product probably won’t work. If the product doesn’t work then something very expensive, very bad or maybe very deadly will happen very quickly. This is THE signal. This defines the world of high-performance critical cleaning.

If your products need to work the first time, every time, all the time, then you have a critical cleaning application and you need the critical cleaning answers from MicroCare.

Question 45

What Is the Reliable Care Way?

Accepted Answer

Before buying or using any chemical, SAFETY COMES FIRST. MicroCare has established a program which is available to customers free of charge to support the products we sell. MicroCare will work with companies to design and implement proper cleaning processes. Our specialists will help specify the features needed on the degreaser to use the solvent safely. Technicians should know what they are using, why they are using it and how to use it properly. They should know safe handling and storage. Emergency procedures should be well-developed and thoroughly understood.

All of this information is included in the Reliable Care Way program. This program will educate your technicians about the cleaning fluid, audit your procedures to ensure worker safety, and monitor your program for deviations which might indicate an unsafe condition is developing.

Please contact MicroCare if you have additional questions or would like to arrange an educational safety seminar for your employees.

Question 46

What Is nPB?

Accepted Answer

“nPB” is an abbreviation for “Normal Propyl Bromide” or “1-bromo-propane” indicated by the CAS #‎106-94-5 on Safety Data Sheets. It replaced ozone depleting Freon and 1-1-1 Trichloroethane.

It is a relatively inexpensive, nonflammable, versatile chemical that removes many types of contamination, such as oils, grease and fluxes. It was formerly used in aerosol cleaners, but due to environmental restirctions, is limited to use as a industrial cleaner inside vapor degreasers today.

nPB (n-Propyl Bromide) has been widely used as an effective and reliable industrial cleaner for metal parts since the 1990’s. But now it is under scrutiny by the U.S. EPA (Environmental Protection Agency), OSHA (Occupational Health and Safety Administration) and ACGIH (American Conference of Governmental Industrial Hygienists).

In 2014, the permissible exposure limit of nPB went from 10 ppm (parts per million) down to just 0.1 PPM. In 2018, the EPA added nPB to its TOSCA (Toxic Substance Control Act) list. In August, 2020 the EPA reported that nPB presents unreasonable risk to human health and should be restricted as a cleaner or degreaser. This report is just a preliminary step for the EPA. It will likely lead to a complete EPA ban on nPB by the end of 2022.

nPB is already sunset or banned in Europe as of July 2020. And many other countries are likely to follow and ban the use of nPB in the near future.

Fortunately, there are a number of nPB replacements that will clean just as well, if not better than nPB inside a modern vapor degreaser. Many of the nPB replacement cleaning fluids provide consistent cleaning quality, cost savings and better throughput. Plus, they have better toxicity profiles making them safer for people and the planet.

Some popular nPB replacements include:

Tergo™ XCF2 An environmentally sustainable azeotropic cleaner engineered for fast, consistent and economical cleaning in vapor degreasers
Opteon™ SF80 Cleaning Fluid Opteon™ SF80 combines the high solvency needs for industrial cleaning with and environmentally-friendly low GWP (Global Warming Potential)
Other custom formulations and pending prototype currently in development may also be available

Question 47

What Are Halogenated Solvents?

Accepted Answer

The family of chemicals called “halogens” include bromine, chlorine, fluorine and iodine, among others. The term “halogen” means they are all in the same column on the periodic table of the elements (if you’re interested, see col. 17 on the right-hand side of the table). Notice all four chemicals are good cleaners. These solvents are used for all sorts of precision cleaning applications. They can be used to remove fluxes from circuit boards or to degrease tiny metal parts. They rinse away particulate and they also can be used to deposit coatings and lubricants. It is an incredibly versatile group of chemicals.

Some companies and countries have restrictions on the use of halogens in fluxes or solder pastes that might remain on PCBs after manufacturing. In additon, some countries are banning some brominated and chlorinated cleaners like nPB (n-propyl bromide) and TCE (trichloroethylene).

If you're currently using these solvents, it's time to start planning your transition to a more environmentally stable cleaning fluid. One good option to consider is Tergo™ XCF2 . It cleans just as effectively, if not better, but doesn't have the safety or air quality concerns associated with nPB or TCE.

Column 17 of the Periodic Table of the Elements shows the halogen family of chemicals.

Question 48

Can I Use nPB in My Cleaning System?

Accepted Answer

nPB is a strong, affordable, versatile, nonflammable industrial solvent. nPB is a great degreaser and defluxer. However, npB does have toxicity worries. nPB is banned in Europe as of July 2020 and other countries currently have nPB under scrutiny.

In the 1990s when nPb was first introduced, the toxicity level for nPB (also known as “TLV”, “AEL” or “PEL”) was set at 100 parts-per-million (ppm). At that level, nPB could be safely used in degreasers and in aerosols. Many companies used it for benchtop cleaning during rework and repair, and even more used it for spray degreasing precision parts.

But now nPB (also called “normal propyl bromide”) has toxicity worries. Governmental agencies in the the Europe, U.S., Canada and elsewhere around the world have been moving to restrict its use. Recent health studies have found nPB damages the nervous system, alters human DNA, impairs fertility and there is a risk of cancer.

Based on these reports, the European Chemicals Agency (ECHA) listed nPB as a ‘Substance of Very High Concern’ in December 2012 and nPB is banned in Europe as an industrial cleaner as of July, 2020.

The government of Ontario, Canada, also concerned about the long-term toxicity of nPB, enacted new worker-safety rules which restrict the deployment of this widely-used chemical in July 2017.

In the Unites Sates, several government agencies recommended 10 ppm as the proper exposure limit. Separately, California adopted a 5 ppm limit and an independent safety agency. In 2014, the American Conference of Governmental Industrial Hygienists (ACGIH), lowered their recommended exposure rating to just 0.1 ppm. In 2020 the EPA announced nPB presents an unreasonable risk to human health when used as a cleaner inside all vapor degreasers including open-top, in-line and closed-loop models.

Today there are new and highly viable alternatives that work as well and are far safer. Companies are developing and commercializing non-toxic, environmentally-acceptable cleaning options that out-perform older fluids. Modern, non-flammable solvent cleaning can make a substantial enhancement to the performance, reliability and longevity of electronic devices. There also are now products on the market which have all the desired chemical traits — such as low viscosity, low surface tension and high Kb values — which allow them to deflux and degrease very effectively. The latest entries in the race are the new “HFO” solvents, available from a number of providers. These clean very well, are safe for people and have exceptional environmental characteristics as well.

Not only do these new products work better, but they stand up to the evolving regulatory requirements imposed by the long list of governing bodies around the world. Formulations are now cleaner, greener and safer.

The future for nPB is no longer in doubt. You can use it for now. But it’s getting close to the time to make a change. Most experts agree, the nPB phaseout is definite and can be as soon as 2023. Plan your transition to safer vapor degreasing fluid now.

Question 49

Can I Use TCE (Trichloroethylene) In My Vapor Degreaser?

Accepted Answer

It is no longer recommended to use trichloroethylene, also called TCE or trike, CAS #79-01-6. While TCE was widely used since the 1950s, it is an old-style chlorinated solvent that generally should be avoided in today’s environment. The main advantages of TCE is that it is inexpensive, widely available and cleans very well. However, it is a proven carcinogen, which may create long-term liabilities for companies that use it. There are newer, better, safer alternatives for you to select.

Specifically, in 2011 the US EPA wrote:

“Based on the available human epidemiologic data and experimental and mechanistic studies, the U.S. Environmental Protection Agency has concluded that TCE poses a potential health hazard to the human central nervous system, kidney, liver, immune system, male reproductive system, and to a developing fetus. TCE is characterized as carcinogenic in humans by all routes of exposure for kidney cancer. There also is human evidence of carcinogenicity for non-Hodgkin Lymphoma, more limited evidence for liver and biliary tract cancer, and some evidence is found for bladder, esophageal, prostate, cervical, breast, and childhood leukemia, and breast cancers.”

TCE is already sunset as a cleaner in Europe and requires special authorization for use. Other countries will most likely follow and restirct or ban TCE altogether.

Learn more about how to replace TCE with this free eGuide.

Question 50

Can I Use IPA in a Vapor Degreaser or Ultrasonic Cleaner?

Accepted Answer

The short answer almost always is, NO, don’t do this. It can be extremely dangerous. YouTube has a number of videos showing people cleaning parts in ultrasonic machines filled with IPA alcohol. Here at MicroCare we always are amazed at this. It is absolutely not an acceptable industrial process.

Some people use IPA alcohol or “white spirits” in ultrasonic tanks to get better cleaning. This is a very dangerous choice and is not recommended. Why? Because when an ultrasonic transducer fails, it will shoot all of it’s electrical energy out of the transducer and into the cleaning fluid. If this is a flammable liquid you end up with a really nasty fireball. So if you must use ultrasonics, you must use a nonflammable solvent.

Another risk stems from the vapors that can accumulate over an ultrasonic tank. Ultrasonic agitation heats the cleaning fluid and creates vapors above the surface of the liquid and over the machine. If the machine is not completely and properly ground, a tiny spark of static electricity can ignite those highly-oxygenated vapors. Again, fireballs are consider poor work-place hygiene. Take a look at these college kids who are able to toast bread with the the spark from static electricity. If you think static isn’t a factor in your factory, then you haven’t looked.

If your company really needs to get these parts properly and consistently cleaned, vapor degreasing with a modern, nonflammable solvent might be a better choice for you. Vapor degreasing approaches the problem completely differently and generally produces clean parts at the lowest cost per-part-cleaned.

A screen capture from a Youtube video showing the surprising power effect of static electricity. Voltages like this could set any flammable solvent in an ultrasonic tank on fire

Question 51

What's the Difference Between an Aqueous Ultrasonic Cleaner and a Vapor Degreaser?

Accepted Answer

Most ultrasonic degreasers are single-tank systems containing a slow-drying nonflammable liquid, such as water, enhanced with a soap or saponifier. These machines are simple, inexpensive, and easy to use. But they do not deliver the highest quality cleaning because they have no way to rinse the contamination from the parts being cleaned.

In contrast, vapor degreasing uses at least two tanks (also called sumps) inside the cleaning system. The tanks have different names: one is the “boil sump” where the cleaning happens, and the other is the “rinse sump.” Those tanks are filled with a specialized non-aqueous, nonflammable cleaning fluid, never water, optimized for the type of contamination being removed. There are many choices for these cleaning fluids, but most of these cleaning fluids have a couple of traits in common: they boil at relatively low temperatures (typically 40˚C instead of the 100˚C of water) and they have the right chemical characteristics (surface tension, density, etc.) to deliver fast and easy critical cleaning.

Now there are many nuances to this discussion, more than we can put into this FAQ. But basically the differences between aqueous ultrasonic cleaning and vapor degreasing are night and day. Aqueous ultrasonic cleaning is cheap, but also slower, and more limited. Vapor degreasing is fast, safe, economical, consistent, and delivers absolutely perfectly and consistently clean parts, every single time.

How clean do your parts need to be? If you need perfect cleaning, quickly, easily, gently, safely, inexpensively, then you need a vapor degreaser.

Question 52

Will Spec Clean™ Ultrasonic Cleaner Solution Work with Ultrasonics?

Accepted Answer

Yes, Spec Clean Ultrasonic Cleaner Solution works very nicely with ultrasonics. Vapor pressure and surface tension are the two most important fluid properties governing the formation of cavitation in ultrasonic cleaning systems. Modern, planet-friendly solvents typically have low vapor pressure and low surface tension, so they cavitate nicely. Most commonly, ultrasonics are added to the rinse sump of the vapor degreaser to enhance the final stages of cleaning. Frequencies can range from 20 khz to 140 khz and even higher; varying the ultrasonic frequency and “sweeping” across the spectrum can substantially improve cleaning results. The cavitation which can be obtained with solvents and ultrasonics result in excellent cleaning.

This contrasts with water cleaning, which high a high vapor pressure and high surface tension. For this reason it’s hard to get pure water to cavitate. Because of all this, traditional, single-tank ultrasonic cleaners most often use water with some type of surfactant to enhance the cleaning process. While the surfactants can’t change the other characteristics of water, they at least can lower the surface tension to improve the cavitation. Some people call this type of additive a “coupler.”

Spec Clean Ultrasonic Cleaner Solution is made specifially for cleaning medical, dental and veterinary instruments including jointed forceps, orthodontic pliers and scissors.

Question 53

Which Precision Cleaning Fluid Is the Mildest?

Accepted Answer

Very gentle, mild cleaning often is required when (a) cleaning substrates made from delicate materials, or (b) when the contamination is light, or (c) when the principle contamination being removed is water. Milder solvents generally are noted as having a low Kb value, typically 20-40 or so (a high Kb value is 100+). Many mild solvents also include an additive to improve the stability of the solvent or to break static bonds, allowing the solvent to more easily remove particulate.

The mildest solvents in the MicroCare portfolio typically would be Vertrel XF, Vertrel XP and MicroCare CCA.

Question 54

Which Precision Cleaning Fluid Is the Strongest?

Accepted Answer

In general, cleaning strength is measured by the Kauri-Butanol rating (Kb Value) of the solvent. Higher Kb values generally correlate with stronger, more aggressive cleaning. Higher Kb values also may be associated with materials compatibility issues. A high Kb value solvent, for example, might craze soft polycarbonate plastics. The trade off is to balance a milder solvent with longer cleaning cycles.

MicroCare offers a large family of cleaning fluids with a variety of Kb values, which enables engineers to fine-tune their cleaning process. In general, the strongest cleaners are Tergo XCF2, Opteon SF80 Specialty fluid, and Vertrel SDG Degreaser. In aerosol packages, the Heavy-Duty Flux Remover — SuprClean™ and the Lead-Free Flux Remover — PowerClean™ probably are the two strongest, most popular choices.

Part Number	Package	Weight	Size	Technical Data Sheet	Safety Data Sheet
SDGGL MCC-SDGGL	Glass (Sample Only)	1.4 kg 3 lbs.	1 L 1 Quart	TDS USA (ENGLISH) (opens in a new tab)	SDS Lookup (opens in a new tab)
SDG0GG MCC-SDG0GG	Glass	4.5 kg 10 lbs.	3.9 L 1 Gallon	TDS USA (ENGLISH) (opens in a new tab)	SDS Lookup (opens in a new tab)
SDGP MCC-SDGP	Metal	4.5 kg 10 lbs.	3.9 L 1 Gallon	TDS USA (ENGLISH) (opens in a new tab)	SDS Lookup (opens in a new tab)
SDGD MCC-SDGD	Drum	226.7 kg 500 lbs.	200 L 55 Gallons	TDS USA (ENGLISH) (opens in a new tab)	SDS Lookup (opens in a new tab)

Part Number	MCC-SDGGL	MCC-SDG0GG	MCC-SDGP	MCC-SDGD
Package	Glass (Sample Only)	Glass	Metal	Drum
Weight	1.4 kg 3 lbs.	4.5 kg 10 lbs.	4.5 kg 10 lbs.	226.7 kg 500 lbs.
Size	1 L 1 Quart	3.9 L 1 Gallon	3.9 L 1 Gallon	200 L 55 Gallons
Technical Data Sheet	TDS	TDS	TDS	TDS
Safety Data Sheet	SDS	SDS	SDS	SDS

Appearance	Clear, colorless liquid
Odor	Ethereal, very slight
PEL (ppm, 8-hr TWA)	200
Boiling Point	43°C / 109°F
Chemical Family	HFC
Evaporation Rate	Very Fast
Cleaning Strength (Kb)	95
Active Ingredients	HFC Mixture with Trans
Flashpoint	None
Global Warming Rating (100yr)	148
VOC Organic Content (g/L)	1,150
Ozone Impact	Zero
Safety Rating	NA
Specific Gravity	1.29
Surface Tension	21.2 dyn/cm @ 25°C
Vapor Pressure @ 20ºC	7.5 psia

Vertrel™ SDG Specialty Fluid

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Precision Cleaning Fluids