White Residue after IPA wash

[pushycat]

Despite markets are flooded with fake and adulterated IPA which are sold for cheap, I use pure IPA from a known supplier. I repair chip level faults and usually wash the repaired area with IPA to remove any flux and other residues. In some PCBs after washing, i see a white residue after washing and IPA has dried. I am just curious to know if this is due to some flux, Solder, or my IPA is adulterated? Please share your experience in this regard.

[Sideshow Bob]

OK so you wash your PCBs in Indian Pale Ale. That is borderline Alcohol abuse if you ask me. The white residue is probably foam
No just kidding here you are dig in
https://www.google.com/search?q=The+Dreaded+White+Residues%3A+Why+They+Form+%26+What+To+Do+About+Them

[pushycat]

OK so you wash your PCBs in Indian Pale Ale. That is borderline Alcohol abuse if you ask me. The white residue is probably foam
No just kidding here you are dig in
https://www.google.com/search?q=The+Dreaded+White+Residues%3A+Why+They+Form+%26+What+To+Do+About+Them

Yes. Indian market is full of cheap substitutes and differentiation in such cases is near impossible. I had seen IPA mixed with water too. I faced this problem previously but now was puzzled if it is specifically due to my IPA.  I just bought 15 litres and this residue is only on some PCBs which comes for repairs. While we use same IPA on our production line where it cleans without any issues.

[Vineyards]

It is normal to assume that different resin types were used on your PCBs. No-clean types can leave a residue when cleaned with IPA. The water content threshold for IPA can be as high as 30%. The so-called pure IPA used in electronics can have a water content of up to 1%. The purer the alcohol, the more prone it is to evaporation. If the cap of the IPA container is left open, the water content may reach approximately 2% after one hour, depending on the humidity and temperature of your room. Each passing hour will add another 1%. That of course, renders it unfit for delicate cleaning as the water content will cause corrosion (oxidation) on metals, and cause contamination, which is unacceptable for RF or High Z circuitry.