[volt-nuts] low emf solder

[David]

On Sat, 29 Oct 2016 20:41:48 +0200, you wrote:

>On Sat, 29 Oct 2016 15:27:49 +0100
>"Dr. David Kirkby (Kirkby Microwave Ltd)" <drkirkby at kirkbymicrowave.co.uk> 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.
>
>...
>
>			Attila Kinali

Wide copper "straps" replaced gold and aluminum bond wires in high
performance power devices more than 10 years ago.  I think I first
heard about it from IRC (International Rectifier Corporation) for the
drain connection in TO-220 power MOSFETs to improve the Rds(on) which
was becoming limited by the package.  These days it is used with SO-8
and other packages as well.