What is this white chalky substance?

[gizmo1990]

I've been doing some work on my 500 plus board, removing and socketing some chips and replacing the Gary socket. After using some white vinegar and then washing down with isopropyl I'm noticing the area has a sort of chalky film over it?

Does anyone know what this is and what could be causing it? Could it be to do with washing the board down with water some time ago? I do live in a very hard water area? Thats the only thing I can think of.

[Kin Hell]

London water is chalky for sure.

Why don't you scrub with Isopropyl again & rinse with bottled distilled water?
This is de-ionised water & should remove all traces of any residue.

After that, swill with Isopropyl again & leave to dry. It is a self evaporating agent so buy the highest/purist alcohol content you can.

[pandy71]

If isopropyl alcohol has to many water (medical alcohol - rub alcohol - is usually 60..72%) then flux may give such chalky remains also similar situation may happen when high humidity is present during washing PCB with alcohol. I usually use acetone to remove such stains completely.

I would neutralize vinegar with some base mild solution then wash thoroughly with distilled water and in final use IPA. Vinegar may be present if not neutralized with base solution and corrode with time (also it may other side effects).

[wiz12]

Did the board suffer any capacitor or battery leakage?

[gizmo1990]

Thanks for the replies everyone.

I've been using 99.9 isopropyl. I put some distilled water over it and it did clear it up a little. Although there does seem loads of it still.

I think what I'll do is give the whole board a good soak in mild soapy water along with a scrub with a soft toothbrush. Then wash it down with distilled water and finally use ipa as suggested. I've not done that previously just been cleaning in spots. Hopefully acomplete wash down will fix it.

@wiz12 Yes the battery did leak unfortunately. I'm in the process of trying to get it working. Repair thread is here.
https://eab.abime.net/showthread.php?t=109506&page=2

[Kin Hell]

Originally Posted by gizmo1990

Thanks for the replies everyone.

I've been using 99.9 isopropyl. I put some distilled water over it and it did clear it up a little. Although there does seem loads of it still.

I think what I'll do is give the whole board a good soak in mild soapy water along with a scrub with a soft toothbrush. Then wash it down with distilled water and finally use ipa as suggested. I've not done that previously just been cleaning in spots. Hopefully acomplete wash down will fix it.

@wiz12 Yes the battery did leak unfortunately. I'm in the process of trying to get it working. Repair thread is here.
https://eab.abime.net/showthread.php?t=109506&page=2

That's a good call. - The huge blister on the silk screen suggests something leaked at some point with an acidic attitude.

Might be worthwhile checking for local via's & traces that might have been affected in that area.

I'm not familiar with the motherboard specs, sorry.

[wiz12]

If you have a look at this video, Adrian comes across this white salt like substance which is a residue caused after leaked electrolyte. The only way of clearing it up seems to be a lot of scrubbing using vinegar and IPA.

[ Show youtube player ]