Intel OverDrive Epoxy

[ph4nt0m]

Does anyone know what kind of epoxy Intel has used on their ceramic 486 and Pentium overdrives? Looks like some industrial stuff with barium titanate (BaTiO3) or graphene.

Is there any better way of removing it rather than painfully scratching it away? Heat gun and various solvents don't seem to help.

[ph4nt0m]

It's awkward to answer my own question, but anyway. Hydrochloric acid (HCl) and sulfuric acid (H2SO4) are of no use, but 70% nitric acid (HNO3) softens surface of this epoxy, turning it into something rusty which can be scratched away much easier. Although concentrated HNO3 is highly corrosive as it destroys nearby tin, lead and copper, even eats through gold coating if exposed to for a long time, so precautions should be taken.

[crazybubba64]

I'm not sure if it is the exact same stuff as was used on some of the older socket 4 Pentium chips (but it seems pretty similar).

Have you tried a long soak in high percentage isopropyl alcohol?

I soaked a Pentium 60 in 90% isopropyl for a week or so, scraping away at the epoxy/ceramic stuff every day. It took around a week to get most of it off, but it did end up coming out pretty nice all things considered.

[ph4nt0m]

I think it's not the same, different colour. I have tried isopropyl, not for a week of course, no difference. Ethyl acetate is a stronger solvent, no effect either, but also not for a long time. It evaporates quickly. Excellent for PCB washing after BGA rework though.