On Sat, 29 Oct 2016 15:27:49 +0100 "Dr. David Kirkby (Kirkby Microwave Ltd)" <[email protected]> wrote:
> But if one could use copper as the bond wire, rather than gold which is > quite common, then it would give you very little thermal EMF Copper is more and more used for bonding wires. See: http://www.ti.com/lit/wp/sszy003/sszy003.pdf http://link.springer.com/article/10.1007/BF03214983 https://nepp.nasa.gov/files/26611/2015-370-Rutkowski-Final-Paper-NEPPweb-Copper-Wire-Bonds-TN26444.pdf But be aware, that the bond pad on the chip is still aluminium in most cases I don't know whether there is any process that uses copper bond pads at all. As far as I know, all of the relevant processes for analog designs (ie those with node sizes over 130nm) still use aluminium interconnect only. IIRC the first node size that got copper interconnect was 65nm and about 10 years ago. > I would have thought any impurities in copper wire, would be quite small, > as it would reduce the electrical conductivity. Whilst I accept one is not > going to get 100.0000000000000000000000 % pure copper, I would have thought > the effect of any impurities at least an order of magnitude less than using > solder. I'm only postulating this - I have no evidence to back it up, and > have never studied the subject. The normal copper wires you get are usually 99.9%. If you go for the oxygen-free variant you can get to 99.99% (don't ask me whether the audiophool grade is really that pure). I have no idea how much the EMF of the impurities is. Attila Kinali -- Malek's Law: Any simple idea will be worded in the most complicated way. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
