Pentium 4 heatspreaders - gold content

[ohminator]

After collecting around 110 pcs. gold plated Pentium 4 heatsink plates, I decided to process them in a little sulfuric cell.
A 100 ml beaker half filled with 98% acid and a 12 V PC power supply were used for the setup.
The plates stripped very quickly (ca. 5 sec).

After collecting the sludge, washing, dissolving in HCl/Cl, filtering and precipitating I received ~0.1 g of gold powder.
So you can specify the gold content per plate with about 1 mg.

 

[silversaddle1]

Can you tell us how you removed the plate from the CPU?

 

[g_axelsson]

Great post!

I have a bag full of heat spreaders that I was going to do exactly the same to. I removed the plates by taking a thin bladed knife and cutting the glue between the metal plate and the circuit board. Then with a twist I broke off the plate.
Some of the heat spreaders are soldered to the CPU die with an indium solder. When soldered, most of the times the die was ripped off the small circuit board.
I dissolved the indium solder by covering the heat spreaders with HCl, planning to try to recover the indium just for fun. But I made a mistake, I let the heat spreaders stay too long in the HCl and it started to dissolve the copper. So my indium chloride is mixed up with a lot of copper chloride too.

Well, that's the result of having too much to do. 8)

If time permits I'll process my heat spreaders in the weekend.

Göran