Desoldering and soldering IC's with solder underneath the body

[kevinm34232]

What's the best way to safely remove these chips where there is a pad of solder underneath the chip? I've tried several techniques, the hot air gun will work but I've had damage to the traces and sometimes the chip will come off taking the big trace under it with it.. What's a good temperature to use? Would a combo of ChipQuik on the pins and hot air work best?

And finally what's the best procedure for resoldering the chip back to the board, especially underneath the chip? Solder paste? Thanks!

[mmartell]

Re: Desoldering and soldering IC's with solder underneath the body

You are not getting the chip hot enough. My method is def not scientific but it works. Heat up the bottom for a bit then concentrate on the top. Use a tool small enough that you can gently wedge under a corner of the chip with very little pressure. Tug gently on it just to guage how things are going. When the chip is hot enough you should be able to flip it over with no resistance.

I set my station to max, 500f and about 4/10 speed. And I use solder paste for beneath the ic.

[kevinm34232]

Re: Desoldering and soldering IC's with solder underneath the body

Thanks, and for resoldering are you tacking the legs down then heating up the body again to get the paste underneath?

Oh and do you just use hot air, and flux on the pins?

[mmartell]

Re: Desoldering and soldering IC's with solder underneath the body

I drag solder the pins then use hot air from below to heat the pad.