Composite die-attach materials for high-temperature packaging applications

Devices based on SiC can potentially be used at temperature up to 600°C. However, technology is needed to package SiC devices such that they can be reliably operated at these high temperatures. Materials that are typically used in low temperature packages are not suitable for high temperature use. Also stresses from mismatched coefficients of thermal expansion (CTE) increase with larger thermal cycles and so the potential for fatigue failure is greater with higher temperature operation. This paper focuses on the processing of selected composite solder joints based on Au-Sn with the potential to achieve tailored thermal expansion coefficients. Microstructure of the joints and the effect of processing on the microstructure are outlined.