What Is a Kb Value? What Does It Tell Me About My Cleaning Fluid?

How well a fluid will clean depends on several variables including: the contamination the selected solvent the application the cleaning system the physical shape of the parts being cleaned When is pH a Good Enough Measure? While the pH of a cleaning fluid can be a good indicator of a fluid’s cleaning strength, 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 . pH measures the acidity or alkalinity of a fluid in comparison to water. The range goes from 0 – 14, with 7 being neutral. 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. Why Use the Kb Value? Many types of contamination are not water-soluble. Non-aqueous solvents are a good choice for those cleaning jobs. Cleaing fluids are neither acidic nor alkaline; the pH test simply isn’t relevant because solvents don’t contain any water. That’s when the Kb value is your best guide to how strong a cleaner is. The cleaning strength or solvency of non-aqueous cleaners usually is measured by an industry benchmark called the Kari-Butanol test. It is an industry standardized ASTM test (Method D-1133) that calibrates the relative strength of a cleaning fluid by immersing a test material called butanol — a thick, rubbery, eraser-like gum — in the solvent for a certain period of time under controlled conditions (e.g., temperatures, pressures, etc.). The lab technician then measures the remaining gum to determine the quantity of material that was dissolved by the solvent. It’s simple, fast and easy. The result of the test is an index called the Kari-Butanol, or Kb value. The working ranges of Kb values go from 10 (very mild) to 200 or even higher (very strong cleaning). For years, the Kb value has been used to judge the relative cleaning “power” of cleaning fluids used on electronics, metals, optics and elsewhere. The Kb value is usually reported on MicroCare product spec sheets as “Kb value.” A higher Kb value is better and means the cleaner is more aggressive or active. Mild cleaners have low scores in the tens and twenties; powerful cleaners like the old chlorinated solvents have ratings in the low hundreds. Soft, mild MicroCare cleaners like the Alcohol-Enhanced Flux Remover – ProClean™ have Kb values in the mid-30s. Stronger cleaners, like the Heavy Duty Flux Remover – SuprClean™ , will have values of 75-130. Even Kb Values Have Their Limits While it is convenient to state that higher Kb values indicate a “stronger” cleaner, 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. There are some solvents that cannot be evaluated using the Kb method since they dissolve the kauri gum almost instantly. Also, the original Kb test calibrated petroleum products but now it has been stretched to measure brominated, fluorinated, chlorinated, and other liquids. In other words, people are asking for the Kb test to deliver more than it can consistently provide. Using Kb Values to Guide Cleaning of Fluxes, Oils and Grease There is a general relation between the Kb value of a cleaning fluid and its capacity to clean fluxes, oils and grease. At MicroCare, our product specifications for cleaning fluids always include a Kb value to help you decide on the best solvents for the job you’re facing. Cleaning fluids with lower Kb values will dissolve greases but may not handle ionics and fluxes. Cleaning fluids with higher Kb values may be speedy and effective flux removers but attack plastic components or remove inks. Selecting a cleaner with the optimal Kb value is a balancing act. There are trade-offs. Many 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. 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. In addition to the Kari-Butanol test, many engineers are also using systematic procedures to rigorously test cleaning fluids on their components, their contamination and their cleaning processes. This makes sense because it’s a test of real-world conditions. Often, the results are unexpected: the relatively mild fluids clean as well as or even better than cleaners with much higher Kb values. Informally, we call these surprising results “operational Kb values.” In these real-world cleaning of oils and fluxes, many MicroCare fluids clean much more effectively than the Kari-Butanol test would suggest while maintaining excellent materials compatibility. Special Note: You cannot compute a Kb value for a water-based cleaner, and you cannot compute a pH value for a solvent cleaner. Aqueous cleaners are profiled using the pH test for acidity or alkalinity. Different chemistries require different tools. Special Note: The benchmark resin actually is the sap from the kauri tree ( Agathis Australis ) that only grows in New Zealand. Chemists searched for a solvent to liquefy that resin to make it useful industrially. They found that the gum was easily dissolved in butyl alcohol, so that became the benchmark solvent and is the source of the name of the test, the Kauri-Butanol test.

What's Best for Cleaning RMA Fluxes and Pastes?

Some PCB makers are using the dip-and-brush method to clean circuit boards during rework and repair. However this process doesn't allow you to easily rinse contamination off the PCBs after they are scrubbed. Other companies use high-pressure aerosols to blast the contamination off the board, but that often wastes cleaning fluid due to overspray. At MicroCare, we think the best way to clean PCBs is with the TriggerGrip™ cleaning system with a planet-friendly cleaning fluid . The TriggerGrip™ system allows you to obtain great cleaning quickly, easily and without a lot of chemical waste, even under tight-fitting BGA components. For R, RA, RMA and SA fluxes and solder pastes, the best choices from MicroCare have high density, high Kb values, low surface tension and low viscosity. The best choices might be: the Heavy Duty Flux Remover — SuprClean™ , the General Purpose Flux Remover and the Alcohol-Enhanced Flux Remover — ProClean™ . Messy aerosol sprays volatilize the cleaning fluid, exposing workers to fumes. The excess fluid also can puddle below the cleaning site, creating a flammability hazard if the solvent has flammable characteristics

Which Cleaner Is the Best to Remove HumiSeal 1B31 (Acrylic Conformal Coating)?

We are using MicroCare DC1 for lacquer removal, Humiseal 1B31. It works OK, but not perfect, and we do quite a few each day. Is there anything better? (Editor's note: 'Lacquer' is a term often used in Europe to describe conformal coatings.) We're a little surprised the No-Clean Flux Remover - VeriClean™ (#MCC-DC1) works at all. This cleaner is siloxane-based and is the best choice for silicone conformal coatings. Humiseal 1B31 is an acrylic. According to the Humiseal product spec sheet, “HumiSeal 1B31 is a fast air drying, single component, acrylic coating that provides excellent moisture and environmental protection for printed circuit assemblies.” Acrylics are best removed with the Lead-Free Flux Remover - PowerClean™ (#MCC-PW210A) or the Heavy Duty Flux Remover - SuprClean™ (#MCC-SPR) both of which are fast-drying, nonflammable, high Kb flux removers. You'll find them much better choices for cleaning the thin, hard acrylic coatings. Try one of them and you will see the results are much faster and better. Be advised the one type of confiormal coating we CAN’T remove are the “thermoset” materials, which take a heat-cure process, such as epoxies and Paralene. SuprClean™ is a powerful, HFC-based fluid used for traditional (RMA) fluxes, solder pastes, plus oils, grease, some inks and acrylic conformal coatings.

Do I Need Gloves When Working With MicroCare Cleaners?

While casual and intermittent skin contact with most of the MicroCare cleaners does not represent a significant health risk, wearing gloves is certainly is a good practice, especially if skin contact is likely and prolonged. This is particularly true when cleaning stencils by hand, using the presaturated wipes . Gloves, splash goggles, aprons (when handling open drums) and safety shoes with steel toes are highly recommended. Common sense strongly recommends that prolonged or repetitive skin contact with any solvent or chemical should be avoided. After all, the MicroCare solvents are defluxers and degreasers. They are designed to remove oils and grease. 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. But why work so hard? Wear gloves or finger cots and stop worrying about it. When using solvents for cleaning SMT stencils and other production equipment, most experts recommend the use of gloves Protective Clothing Enhances Worker Safety Whichever solvent you select, you should use gloves and other protective clothing if there is any risk of skin or eye contact. There is a very good web site which has excellent technical data about the huge array of glove choices available on the market. It’s organized by the Office of Environmental Health & Safety (EHS, formerly The Office of Radiation, Chemical & Biological Safety (ORCBS), at the Michigan State University) so it’s not tied to any one manufacturer or brand. When you identify a chemical it suggests the best type of glove to use. In the color chart, you’re looking for gloves rated in white or green. When selecting gloves, check the SDS sheet to get the EXACT chemical name or CAS number for the solvent you are using; different solvents require different types of gloves. As a general rule for MicroCare products, latex gloves work adequately. In some applications a more durable two-part glove might be necessary. Chose the powderless option if it is important to control nonvolatile residues in your production process. These are widely available from quality distributors everywhere. If you don’t have time to go to the ORCBS site, then select the best impervious gloves and protective clothing you can find if there is any risk of skin contact. Gloves, splash goggles, aprons (when handling open drums) and safety shoes with steel toes are highly recommended.

Which Is the Mildest MicroCare Cleaner?

Companies seek mild cleaners for many reasons, but the most common issue is materials compatibility. Strong cleaners deliver great results and clean quickly, but may attack soft plastics, rubber, conformal coatings or remove inks. If this are a concern, then you need for a cleaner with a low Kb value that will not dissolve, craze or attack softer substrates. From MicroCare, the most popular circuit board cleaners that are milder and plastic-safe would be: No-Clean Flux Remover — VeriClean™ Alcohol-Enhanced Flux Remover — ProClean™ IPA-Based Flux Remover – IsoClean™ Among the maintenance cleaners, the milder choices are the Streak-Free Glass Cleaner . Lastly, the Universal Contact Cleaner is a fine nonflammable choice for rinsing insoluble particulate from components.

Which Cleaner is Best at Removing Conformal Coatings?

Conformal coatings are challenging. First, they are designed to be very durable and hard to remove. Then, there are many, many different types of coatings, and many are old formulations which require old solvent which are no longer widely acceptable. Let’s take a look at some good choices for more common applications: Silicone Coatings Dow Corning and other companies produce very popular conformal coatings based on silicones. They offer great protection while being light, durable and easy to rework. Almost without exception, silicone coatings may be removed by either the VOC-Free Flux Remover — UltraClean™ or the No-Clean Flux Remover – VeriClean™ . This product is based on siloxane technologies, so it is chemically very similar to most silicone conformal coatings. In one test with a large Texas computer manufacturer, No-Clean Flux Remover – VeriClean™ removed in two minutes a coating which had been taking 45 minutes to remove with more traditional solvents. Acrylic Coatings Acrylic coatings, like Humiseal 1B31, can be difficult to remove. Your best choice is the Heavy-Duty Flux Remover – SuprClean™ . It is a formidable cleaner with a high Kb value . If it dries a little too quickly for this application, soak the parts in a bath of the solvents. Put a lid on the container so the fluid does not evaporate too quickly. Urethane Coatings Urethanes are challenging to remove. Generally, a powerful, slow-drying solvent will work best, if anything works at all. Try the Uncured ExPoxy™ Remover as one option. Usually, these coatings can be removed with a good, long soaking bath in the solvent. Put a cover on the bath to control solvent evaporation. Epoxy Coatings Epoxy coatings are very difficult. There is no benchtop-safe chemical which can remove a cured epoxy coating, except physical abrasion. If the coating has not cured (hardened) the Uncured ExPoxy™ Remover will be the best option. Usually, these coatings can be removed with a good, long soaking bath in the solvent. Put a cover on the bath to control solvent evaporation. Paralene Coatings Paralene is a military-style coating, very thin and rock-hard. It simply cannot be removed chemically. SuprClean™ is a powerful, HFC-based fluid used for traditional (RMA) fluxes, solder pastes, plus oils, grease, some inks and for cleaning acrylic conformal coatings

Heavy Duty Rosin Flux Remover – SuprClean™ (3M Novec™ Flux Remover Replacement)

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Product Information

SuprClean Heavy Duty Rosin Flux Remover is the best choice for cleaning baked-on fluxes, pastes and greases

Applications:

Removes baked on pastes, fluxes and electronic greases
Cleans R, RA, RMA, and SA materials
Especially effective on rugged, high-temperature solders used on military PCBs
Ideal for heavy-duty degreasing
Easily removes acrylic conformal coatings
Excellent replacement for 3M Novec™ flux removers

Features:

No residue/no rinsing
Strong cleaner – test soft plastics before wide-scale use
Kb Value: 110 (strong)
Fast drying for speedy cleaning
Chemical Family: HFC blend
Nonflammable for added safety
Low odor for a better work environment
VOC Content – Aerosol: 1080 g/L
VOC Content – Bulk: g/L
RoHS/WEEE/REACH/ EPA SNAP compliant
Formulated in USA

SuprClean™ Heavy Duty Rosin Flux Remover is has a low viscosity and low surface tension, making it perfect for reworking today’s tight-fitting components, including even BGA chips. It gets under components, dissolves flux residue and rinses it away. The aerosol cans are both TriggerGrip™ Cleaning Tool compatible and StatZAP™ ESD Eliminator Tool compatible. Economical jumbo-sized aerosol can delivers 30% more cleaner for only 15% more cost.

Product Details

Part Number	Package	Weight	Size	Technical Data Sheet	Safety Data Sheet
SPR 1638 ES1035 ES1631 8278 SPR	Aerosol	0.34 kg 0.75 lb.	260 ml 12 oz.	TDS USA (ENGLISH) (opens in a new tab) Spanish (opens in a new tab)	SDS Lookup (opens in a new tab)
SPR19A SPR19A	Jumbo Aerosol	0.54 kg 1.18 lbs.	405 ml 19 oz.	TDS USA (ENGLISH) (opens in a new tab) Spanish (opens in a new tab)	SDS Lookup (opens in a new tab)
SPRG SPRG	Minipail	5 kg 10 lbs.	3.8 L 1 Gallon	TDS USA (ENGLISH) (opens in a new tab) Spanish (opens in a new tab)	SDS Lookup (opens in a new tab)
SPRP SPRP	Pail	23 kg 50 lbs.	19 L 5 Gallons	TDS USA (ENGLISH) (opens in a new tab) Spanish (opens in a new tab)	SDS Lookup (opens in a new tab)
SPRD SPRD	Drum	227 kg 500 lbs.	208 L 55 Gallons	TDS USA (ENGLISH) (opens in a new tab) Spanish (opens in a new tab)	SDS Lookup (opens in a new tab)

Part Number	SPR	SPR19A	SPRG	SPRP	SPRD
Package	Aerosol	Jumbo Aerosol	Minipail	Pail	Drum
Weight	0.34 kg 0.75 lb.	0.54 kg 1.18 lbs.	5 kg 10 lbs.	23 kg 50 lbs.	227 kg 500 lbs.
Size	260 ml 12 oz.	405 ml 19 oz.	3.8 L 1 Gallon	19 L 5 Gallons	208 L 55 Gallons
Technical Data Sheet	TDS	TDS	TDS	TDS	TDS
Safety Data Sheet	SDS	SDS	SDS	SDS	SDS

Appearance	Clear, colorless liquid
Odor	Slight Ether
PEL (ppm, 8-hr TWA)	200
Boiling Point	41°C / 106°F
Chemical Family	HFC Blend
Active Ingredients	Hydrofluorocarbons and Trans
Flashpoint	None
Ozone Impact	Zero
REACH & ELINCS Compliant
RoHS & WEEE Compliant
Safety Rating	Non-flammable
Specific Gravity	1.26
Surface Tension	Not Available
Vapor Density	Not Available
Viscosity	.48
Vapor Pressure @ 20ºC	37.9

Heavy Duty Rosin Flux Remover – SuprClean™ (3M Novec™ Flux Remover Replacement)

Product Information

Applications:

Features:

Product Details

Safety Data Sheet

AEROSOL

BULK

Technical Data Sheet

Electronics