PGM's on Memory sticks?

[g_axelsson]

Everyone is talking about tin, but it should be solder. 60% tin, 40% lead. In the border zone between solder and copper it would create a lot of different alloys between copper, tin and lead. No wonder that hydrochloric acid has a hard time to dissolve all the solder.

And I agree with everyone that says that the value is in the chips only.

Any talk about conformal coating is just wrong, it would create a good isolating surface and you wouldn't get any electrical contact, kind of contradicts what is sought after, a good electrical contact to conduct the signals between the CPU and the memory.

Göran

 

[patnor1011]

Well I am convinced after running the ones I had that there is no value there - or so little its not worth going after,

The part that still has me stumped is if its tin why doesn't the HCL remove it when used to depopulate them - although a conformal coating as suggested by 27182 would be one explaination.

Kurt

Maybe you seen Nickel under dissolved Tin? Just a thought.

 

[patnor1011]

Digging up an old post here. OK, it's been proven that the silver colored plating IS tin. Do the chips have the same values, by weight, as the gold plated finger ram? Has anyone processed these chips for yields? Patnor, where are you????? :lol:

I processed them and quite a lot of them. Yield? That is a tough one to answer. There is simply too many of different types. Various thickness, internal construction and sizes will throw off any estimation. I got everything from 0.8 (that was smallest yield I got) to 2.5 g from kg of them.
I have seen some IC which I got still in manufacturers packaging that they do contain Ag/Pg solder in them. The one I recall without going after notes were IC called Rabbit.

 

[g_axelsson]

There is no reason to nickel plate copper if you cover it up with solder. It would create a weaker connection to the copper beneath and increase the risk of a bad electrical connection.

The lead in the solder will soon saturate the solution (5g led chloride / liter) and creating a crust instead.

Göran

 

[maynman1751]

Thank You everyone for your answers to my question. 8)