Failure Analysis ofIn/AuSolder Joints

Aimedattheproblem ofIn/Ausolder joints inmicrowave circuit, themicrostructure andcomponents ofIn/Ausolder joints wereanalyzed andthefailure modesfordiebonding by In/Auweredocumented. Thefailure causes werediscussed andpreventive measures weresuggested. Non-control of temperature andoxidation ofsolder lead todecrement ofthe dieshear strength: ifthebonding temperature istoohigh, all goldwouldbeformed Au/Inalloy withindium andnogold layer left; ifthesolder areoxided, whichisresponsible for local non-wetting between goldandindium. According tothe analysis we suggested thatitwouldbebetter tocontrol temperature precise andusetheprotective atmosphere of nitrogen, experiment results significantly favored the processing ofmicrowave circuit. Key word:In/Aualloy; solder joints; microstructure; components; non-wetting