TIL a cheap trick for cleaning flux off old boards

I used to just blast everything with IPA and hope for the best, which left a lot of residue. After a job on a 90s stereo amp last week, I started using a soft toothbrush with a drop of dish soap in warm water first, then a quick IPA rinse. It gets under those old, crusty chips way better. Anyone have a different method for really stubborn, old flux?

3 comments

3 Comments

nguyen.dylan2mo ago

Ever try adding a tiny bit of white vinegar to that soapy water? The mild acid can really help break down that old, hard flux before you scrub. I found it works well on the really baked-on stuff from the 80s and 90s that just laughs at IPA. Just make sure you do a super good rinse with clean water after, then hit it with the IPA to drive off any moisture. You don't want any vinegar left behind to cause problems later.

benlewis2mo agoMost Upvoted

Yeah, @nguyen.dylan, I read that tip somewhere too.

abbychen2mo ago

Saw a post on a retro computing forum where a guy used citric acid powder dissolved in warm water for cleaning old flux. He said it was less harsh than straight vinegar and rinsed cleaner. The ratio was like a teaspoon per cup of water, let the board soak for a few minutes.