Indium Inside
How to get indium metal from obsolete CPUs
Certain Intel CPUS use indium solder to conduct heat from the silicon die to the heat spreader. With a razor blade and prying tool and a little bit of heat, you can extract it, no chemical processing required.
Note that I said "certain." Not all of them use indium solder. Some use thermal paste. It's hard to determine which use solder and which use paste without cracking them open for yourself. Luckily, I've done just this, and while I've hardly opened every CPU they've made, I know of a few examples.
As a retro tech nerd, I ask that you help preserve the history of computing technology by only choosing plentiful and low-end CPUs to scrap. If you can find any that have been tested and aren't working, that's even better. Always check online before you scrap a CPU. It could be worth a lot more as is.
CPUs confirmed to use indium solder:
- Xeon E56xx: confirmed in E5620 SLBV4, best source I've found so far, with large dies and easy-to-remove heat spreaders. Very cheap on eBay. I bought a lot of 20 Xeon E5606s for about $30, and the total yield was around 10 grams.
- Pentium E5500: small die, but they're plentiful as e-waste.
- Pentium D 915 SL9KB and SL9DA: both use two small, E5x00-sized dies.
- Pentium E6800 SLGUE: small die. This is a higher-end Pentium of the time, so I'd hesitate to scrap these.
- Xeon E5-2420V2 SR1AJ: medium die
- Xeon E5-2609V3 SR1YC: huge die, but more expensive. Might still be the best in terms of price per area if you can get them cheap.
- Xeon E5-262xV3: confirmed in 2620V3 SR207 and 2623V3 SR208. Large dies, smaller than the 2609V3.
- Xeon E5-1620V3 SR20P: same as the 262xV3
- Xeon E5-2620V4 SR2R6: medium-small die, uses a hard epoxy instead of silicone around the rim of the IHS. It's a huge pain to get into these. Not worth it IMO.
CPUs confirmed NOT to use indium solder:
- Xeon X3430 SLBLJ
- Pentium E5200 SLB9T
- Pentium E2160 SLA8Z