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I have a PCB with many chips on it - it's a "hashboard" for an ASIC bitcoin miner. There are 63 chips on every hashboard, and each chip has a small heatsink on it.

I tried heating the heatsinks with a hot air gun to remove them, but most of time the chip comes off along with the heatsink, and the chip is still stuck to the heatsink.

Is there any solvent in which I can soak the boards or chips that are stuck to the heatsinks, in order to separate them?

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Dichloromethane appears to be the best solvent, but you could also try acetone. It may take hours to penetrate. A simpler method you could try is boiling the board in water. Check here for reference

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  • \$\begingroup\$ would Dichloromethane or acetone damage the PCB or the IC? \$\endgroup\$ Jul 2, 2019 at 14:45
  • \$\begingroup\$ @AtaMohammadi I think acetone is probably OK - but you need to check that. DCM is rather nasty stuff and I have no idea. In your position I would try boiling water as it is simple and safe. \$\endgroup\$ Jul 3, 2019 at 10:29
  • \$\begingroup\$ Putting the whole PCB on the boiling water would just melt the epoxy, Isn't it? I mean it won't desolder the parts on it, right? \$\endgroup\$ Jul 3, 2019 at 11:30
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    \$\begingroup\$ @As long as the water is pure it shouldn't damage the PCB. Whether it is good at unsticking the parts remains to be seen. You need to do some tests on a board you don't mind losing to experiment. \$\endgroup\$ Jul 3, 2019 at 12:38
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It's usually a thermal epoxy used to adhere heatsinks, there are chemicals which can soften and remove cured epoxies, but they won't be very kind to the PCB they're attached to.

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  • \$\begingroup\$ I have Heatsinks with ICs stuck to them. so they are not on PCB. would those chemicals that you said harm the IC? Could you please name some of those chemicals? \$\endgroup\$ Jul 1, 2019 at 15:09
  • \$\begingroup\$ For epoxy I think nitric acid will dissolve it. It will dissolve the IC too. \$\endgroup\$
    – Colin
    Jul 1, 2019 at 15:14

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