Common CIs-- No mill

[Geld Konig]

It is worthy to processe the new common CIs ( from 1990 to today - no military)? I know that are several wires (very fine ones 25 Angstrongs or smaller that this measure ) that connect the pads to slice of silicon ( CI itself). Now the attached silicon slice is silver with epoxi.The NaCN process( concentration 0,2 to 0,01 %) with using a fish air eletric machine( aquarius) to supply the need O2 to the reaction is the best process? How the best way to break the plastic case to expose the fine wires to CN- solution?

 

[ander]

Angstrom is 1/10 of nanometer, so 25A=2,5nm-> width=couple of atoms-> you can't see them. I suppose you mean 2,5um. My refiener buys polish ICs fo $4/1kg. Plastic can be hard to break. Using cyanide?? :roll: . Calculate-> 1 cubic meter gold is 19,3*10^6g. 1 micrometer is 10^-6 m -> 1 cubic micrometer is 10^-18 m-> 1 meter if wire is then 10^-12 cubic meter of volume. Diameter 2,5um gives 4,9 cubic micrometer vol/ meter. Thus you have 95 micrograms per meter-> 0,095mg/m. If IC has 16 pins and each of them is connected to the chip with 5mm=0,005m wire. you have 0,08m of wire in IC, It's 7,6ug Au/IC-> per gram of gold you need way over 100 000 ICs. I hope calcuations are right, and data are wrong.

 

[goldsilverpro]

ander,

Do they make gold bonding wire as small as 2.5 microns (.0001")? Not that I know of. I have heard that most that is used is either 12.5 microns (.0005") or 25 microns (.001").
http://en.wikipedia.org/wiki/Wire_bonding

If my quicky math is right (please correct me if I'm wrong), an inch of 25 micron gold wire would weigh about .00025 grams and an inch of 12.5 micron wire about .000062 grams. Or, one cm of 25 micron wire = about .0001 g and one cm of 12.5 micron wire = about .000024 g.

A 40 lead IC with 40, 1/4" long, 25 micron bonding wires would contain about .0025 grams of gold (in bonding wires only) = about $.088. If the wires were 12.5 microns, the value would be about $.022.

A troy oz of 25 micron gold wire is about 2 miles long and a troy oz of 12.5 micron wire is about 8 miles long.

 

[Anonymous]

Chris,
Do you know what the silver looking metal that is used to plate the end of the traces and the tab that the silicon chip is soldered to is? or could be?

thanks
jim