Low Temperature Sintered Conductive Adhesives for use in the Packaging of High-Power Electronics

There is a need for improvement in the performance of thermally and electrically conductive polymeric adhesives used in electronic packaging. In particular, there are few polymeric materi-als that are suitable for replacing eutectic solder bonding in electronic devices used in high-temperature environments, such as the operating environment of high power wide bandgap elec-tronic devices. The US Navy Radar development roadmap plans for the insertion of high power microwave devices (High Voltage GaAs, SiC,GaN) into solid-state radar systems by 2007. These new devices will operate at power densities over 10X of current GaAs MMICs. Efficient device cooling is critical towards meeting device performance and reliability requirements. Due to manufacturing considerations, current packaging strategies utilize both solder and thermally conductive adhesives for device bonding. However, most conductive adhesives do not exhibit satisfactory thermal performance and are the majority contributor to thermal rise in device junc-tion temperatures (Tjc). We have developed a low-temperature sintering adhesive that, with some modification, will address these performance issues. Our unique formulation incorporates a novel polymeric resin that can be tailored to cure rapidly over a varied temperature range. It is solvent-free and easily processed. Incorporation of a combination of suitable alloy powders in this resin formulation allows the preparation of composite adhesives capable of forming metal-lurgical connections to a variety of metal surfaces. Additional development will yield adhesives with electrical and thermal conductivity properties similar to solder materials but with the proc-essing advantages of current polymeric adhesives.