Hot air rework station trick I stumbled on last night

I was trying to remove a stubborn QFN chip from a laptop motherboard and my hot air station wasn't cutting it even at 400C. I decided to preheat the board on a cheap hot plate I had sitting around for about 2 minutes at 150C first, and the chip basically lifted off with zero fuss after that. Has anyone else tried preheating like this for heavy ground plane chips, or is there a better way I'm missing?

2 comments

2 Comments

alice24216d agoTop Commenter

Oh man, just a heads up - 150C on a hot plate might actually be too high for some boards since solder melts around 183C and you're getting close to damaging components. Try keeping it more like 100-110C to be safe.

umabailey16d ago

I had the same issue with a Raspberry Pi board last year. @alice242, I kept mine at 120C and it worked fine for the heat gun method since I didn't want to risk killing the USB ports. The trick was preheating the whole board evenly for a few minutes before going in with the hot plate. Some capacitors on my board started acting weird when I tried 140C once, so dropping to 110C saved me from replacing the whole thing. Sticking around 100 to 110C is the sweet spot for most SMD work in my experience.