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.

[madhan7710]

I faced the same issue. all my in house small batch production boards get white residue after cleaning the boards with IPA. i tried changing the IPA but same results. i used to clean the board multiple times after drying completely so that white residues become powder like thing and clean them with dry brush. i repeat the process with IPA again.

Now i tried another cleaning solution which is not IPA or alcohol based. This conncentrate has to be mixed with DM water. the results are super clean. no flux residues. They give excellent results. But as it is mixed with DM water am not sure if it can be used with all type of components. Yet to check the after effects fully. white residue problem is fully solved but need to check if it creates any other issues.

If you are in india then search for FR104 PCB Cleaning solution.

[h0nk]

I faced the same issue. all my in house small batch production boards get white residue after cleaning the boards with IPA. i tried changing the IPA but same results. i used to clean the board multiple times after drying completely so that white residues become powder like thing and clean them with dry brush. i repeat the process with IPA again.

This might be a substance called "Camphor".
Normally You should be able to smell this substance.
Another possible additive would be gasoline.
This should not give any residue.


Best Regards

[MAXPAYNE]

In Bangladesh, I used petrol.... always gave me proper cleaning with no residue than IPA.... :p

[Lorien]

I'm cleaning small batches of my boards using IPA (99,9% pure ... they say!) and I have nice results BUT: I'm using more than one bath and I use a ultrasonic cleaner! On top of that I usually place the boards I want to be cleaned upside down (with SMD parts towards the bottom of the ultrasonic cleaner if are placed one sided). To avoid scratches I'm using 4 plastic PCB standoffs. Be careful about plastic standoffs! Some may react with IPA! I'm not using metal because metal does scratch the ENIG finish of the PCB's mounting holes!
Almost forgot: on each bath I'm wet cleaning them by using a brush (dipped in IPA) an on the last bath I leave the IPA to get a bit warm this way, when I'm getting the PCB from the cleaner the IPA will dry out fast with NO traces of any flux.
 Only PD-223 or UV-223 flux are involved. I had issues with other types I tried... It leaved traces regardless how many times I tried to clean up the PCBs...
I try to stay away of any water variants (DM or other ...)! I cleaned using DM water many years back and had problems with via corrosion. Petrol products are good to a degree but stinks  
 I hope it helps!