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

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 <Many> H20 1.00
IPA Alcohol* <Many> Alcohol 0.79

First Generation

Brand Name or Description Principle Supplier Base Chemistry Liquid Density (kg/liter)
Trichloroethylene (TCE) <Many> Chlorine 1.46
Perchloroethylene (PCE or Perc) <Many> 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) <Many> 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

Tergo™ Generation

Brand Name or Description Principle Supplier Base Chemistry Liquid Density (kg/liter)
Tergo™ Metal Cleaning Fluid MicroCare HFO-110 1.28
Tergo™ CFCF Rinse MicroCare HFO-110 1.52
Tergo™ High Perf. Flux Remover MicroCare HFO-110 1.32
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 valuetoxicityflammability and surface tension, these predict better, faster and more cost-effective cleaning.