[time-nuts] quartz / liquid nitrogen
brooke at pacific.net
Tue Apr 3 14:36:02 EDT 2018
When Aetech started to make their own Tunnel Diodes there was a problem with the neck breaking.
Note they were made by alloying a ball of metal onto a highly doped chip, bonding from the lip of the ceramic package to
the ball then on to the opposite lip, then etching the chip away leaving something that in cross section looked like a
mushroom. The neck was a few microns wide and often broke. The fix was to epoxy a glass rod on either side of the
chip, between the metal bottom of the ceramic pill package and the bonding wire. The glass was chosen to have a CTE
that matched the die. That solved the broken neck problem.
-------- Original Message --------
> And you want your semiconductors to be in ceramic/lided packages with the bond wires flapping in free air. Bond wires embedded in epoxy like to break... don't ask how I found this out ;-) ... it brings back bad memories... and makes bad memories... Quantum chips have very elaborate/specialized bonding to survive liquid helium... even with that, thermal cycling still breaks them.
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