Failure Analysis of In/Au Solder Joints

Aimed at the problem of In/Au solder joints in microwave circuit, the microstructure and components of In/Au solder joints were analyzed and the failure modes for die bonding by In/Au were documented. The failure causes were discussed and preventive measures were suggested. Non-control of temperature and oxidation of solder lead to decrement of the die shear strength: if the bonding temperature is too high, all gold would be formed Au/In alloy with indium and no gold layer left; if the solder are oxided, which is responsible for local non-wetting between gold and indium. According to the analysis we suggested that it would be better to control temperature precise and use the protective atmosphere of nitrogen, experiment results significantly favored the processing of microwave circuit