# 215 cm2 of gold plated CPU caps, about 3 gr of gold



## Renaldas (Aug 30, 2010)

Processed about 215 cm2 CPU caps with gold on both sides, so, gold plating surface area was approx. 430 cm2. The caps weighted about 70 gr, there was some solder remained on each cap. Got about 3 gr of gold.

Lets calculate the thickness out of this figures. The volume of gold is 3 gr : 19,3 g/cm3 = 0,155 cm3. The thickness of gold layer is 0,155 cm3 : 430 cm2 = 0,00036 cm = 3,6 um. What do you think, is it real?


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## samuel-a (Aug 30, 2010)

That sounds right, tough i allways believed it to be much thinner plating...
3.6 um = 141.7 uin

Thanks for the info.


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## goldsilverpro (Aug 30, 2010)

I assume you're talking about CPU lids. I have seen these run about 7% gold (1 tr.oz./#). However, the plating, itself, shouldn't run more than 60 microinches (1.5 microns). There is no technical reason for it to run higher. Most of the value is in the Au/Sn braze around the edge on the bottom side.


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## samuel-a (Aug 31, 2010)

goldsilverpro said:


> I assume you're talking about CPU lids. I have seen these run about 7% gold (1 tr.oz./#). However, the plating, itself, shouldn't run more than 60 microinches (1.5 microns). There is no technical reason for it to run higher. Most of the value is in the Au/Sn braze around the edge on the bottom side.




Maybe there was some AuSn brazing left on the lids lips?
the first type CPU that comes to my mind is Pentium pro that is most likely to use gold brazing for the lid/cap...


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## Renaldas (Aug 31, 2010)

samuel-a said:


> goldsilverpro said:
> 
> 
> > I assume you're talking about CPU lids. I have seen these run about 7% gold (1 tr.oz./#). However, the plating, itself, shouldn't run more than 60 microinches (1.5 microns). There is no technical reason for it to run higher. Most of the value is in the Au/Sn braze around the edge on the bottom side.
> ...



Do Pentium Pro and other CPUs without gold plated lids contain braz with gold? Isn't there a simple tin solder, without any PM?


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## goldsilverpro (Aug 31, 2010)

In every case I've seen, if the lid is not gold plated, the braze will not contain gold and, visa versa.


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