I need to attach a J-leaded ASIC to one side of a ceramic board,
up-side-down, and a custom leadless ceramic part on the opposite side.
The spec for the leads of the ASIC package are: made out of Kovar or Alloy
42. All exposed metal and metallized area shall be gold plated with 60
micro-inches gold (min) over nickel plating.

We would like to attach this part using an solder alloy with a reflow temp
somewhat above that of 63/37, but below 280 C (lid attach temp), so we
won't unnecessarily reflow this part again when it is attached to it's main
board.

We have tried 96.5 Sn/3.5Ag (221 C eutectic) and are being killed with the
gold embrittlement/poisoning.

Any suggestions?

TIA
Charlie B.
281-552-3328 Voice
281-552-3100 FAX
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