|MadSci Network: Computer Science|
Hello John, An interesting question, with a convoluted answer! As I'm sure you know, gold is extracted from ore using the 'amalgamation process' or 'cyanide method'; both quite dangerous. Pure gold is an excellent conductor and is not subject to corrosion (Aqua Regia being the exception), but has some downsides to it - the main ones being its extreme softness and relatively high melting point. For many years, aluminum was used in the production of microchips; now it is (slowly) being replaced by copper because of its better electrical conductivity; necessary in today's higher speed processors. Gold would be a better choice (better conductor), but its higher cost and lack of physical strength make it less desirable than copper. The processor (CPU) goes thru some extreme temperature changes at the metal/silicon junctions, and the thermal expansions/contractions would lead to early failure. Besides, being a sealed unit, the corrosion resistance of gold is not required. Gold is, however, used heavily in the production of LED's. In a LED, the anode wire junction with the active region of the diode must be very small and gold, being extremely ductile, fills the bill very nicely. And, because a LED is encapsulated in epoxy resin and generates little heat, thermal expansion is not a major concern. It is also used extensively on circuit board contacts, where good electrical contact is a necessity. Even so, the gold is usually alloyed with another metal such as copper or platinum, which gives it greater resistance to the abrasion that comes from repeated removal and insertions. So, to answer your question, while very pure gold is necessary to ensure high electrical conductivity, it is almost always alloyed with other metals with desireable physical properties; namely strength and abrasion resistance. At some time in the not too distant future, I'm sure gold, in its pure form (24K) will be needed to handle the ever increasing speed of processors. Even now, manufacturers of CPUs are switching to '.15 micron' technology, where the connection path between the internal transistors is reduced in order for them to operate at 1GHz and above speeds, since propagation delay through connections/('wires') can severely limit the speed at which a CPU can operate. I put wires in quotes because they are not actually wires, but heat/vacuum depositions of the conductive material on the substrate. I hope this answers your question. Your (not-so) Mad Scientist, Karl Kolbus Karl-Kolbus@email.msn.com
Try the links in the MadSci Library for more information on Computer Science.