Repairing IC pins
pkoning at equallogic.com
Fri Jul 22 13:28:43 CDT 2005
>>>>> "Dwight" == Dwight K Elvey <dwight.elvey at amd.com> writes:
Dwight> ... I have a number of RAM IC that are
Dwight> gradually failing because they have the iron cored pins. I
Dwight> guess these were cheaper ...
Probably not. Chances are the pin is actually made of Kovar or some
other oddball alloy like that. Those aren't cheap at all. Their
purpose in life is to match the thermal coefficient of expansion of
the ceramic, so fast temperature cycles don't break the hermetic
seal. This came out of vacuum tube technology, but it applies to
hermetic semiconductors, too.
I don't believe that Kovar can be soldered, but it probably can be
brazed (with nickel?).
Copper would work quite poorly in that application, because the
t.c.e. of copper is far higher than that of any glass or ceramic.
There are ways around that (see John Strong, "Procedures in
Experimental Physics", a brilliant book) but they aren't all that
appropriate for IC packaging.
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