Hi guys and girls!!

I have a question that I think many of you can answer.
Today we solder FET chips with Au/Sn solder onto a DBC substrate with Au surface.
The soldering area of the FET is Chromium/Nickel/Silver.

I want to replace the Au/Sn solder with "something else".. I don't want to glue the chip to place, only solder.
The FET working temperature reaches up to 120degC.

Any ideas on what kind of solder to use? 
__________________________________________________
Jan Merstrand
Microwave MCM, Design/Production Support
Ericsson Microwave Systems AB. Defence Manufacturing
Office address: Bergfotsgatan 2, SE-431 84 Mölndal
Phone: +46 31 747 0725, Fax: +46 31 747 3515

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