TIL flux residue can fry a board even if it looks clean

I used to skip cleaning flux off after soldering if it looked fine. Last week a laptop board came back dead after 3 months and a microscope showed a crusty patch I missed. Has anyone else gotten burned by no-clean flux acting up later?

3 comments

3 Comments

singh.harper3d agoMost Upvoted

Yeah the 'looks clean' part is exactly what got my buddy. He had a drone flight controller die mid-air after six months, and when he scraped under a chip it was all crusty no-clean flux that went conductive from humidity.

troychen2d ago

A buddy of mine had a dashcam fail after a year because the no-clean flux under the main chip turned into a gooey mess. He cracked it open and the board looked fine until he poked a multimeter probe under there and got shorts everywhere.

richarddixon3d ago

Wait, so that no-clean flux can actually go bad like that? I used to think it was set-and-forget, but hearing about your buddy's drone crashing changes my mind, @singh.harper. Guess I owe those glue-heads another look.