Had a laptop board short out right after a reflow in my home shop. What's your go-to method for checking for hidden shorts under BGA chips?

3 comments

3 Comments

So you're saying it was fine before the reflow? That's a big clue. Are you using an infrared heater or a hot air station, because uneven heating can warp the board and cause new shorts. Did you check the simple stuff first, like excess solder paste or flux residue under nearby caps?

kim.diana1mo ago

Ugh, that's such a good point from @sanchez.lucas about warping. I read a whole forum thread where someone kept getting shorts after rework and it turned out their cheap hot air gun had a really bad hotspot. They said the board looked fine but was actually bending just enough under the chip. Maybe it's something like that? I'd definitely go back and clean all the flux off first, like he said, because that can be sneaky conductive. Sometimes the fix is way simpler than the problem feels.

schmidt.eva1mo ago

Disagree completely with blaming the tools right away. Sometimes people just rush the rework and don't let the board cool down evenly, which can cause all kinds of hidden stress. I've seen folks with top-notch gear still get shorts because they skipped basic steps, like checking for solder balls from the first attempt. Honestly, @kim.diana, while that forum story is interesting, it feels like an outlier case. More often it's a technique problem, not a gear problem, and jumping to replace equipment is an expensive guess.