Sintered Conductive Adhesives for use in Active Radar System Thermal Management

Current Naval microwave power amplifiers operate at power densities around 200-500 W/cm2. Amplifiers under development may operate at 2-4 times this power density. Despite the development of active cooling technologies, the principal technology for removing heat from a chip remains thermal conduction. In most power devices, solders, such as AuSn, are used for die attach bonding. Solder is not adaptable to high volume, low cost processing. There is a critical need from T/R module developers for improvement in the performance of thermally conductive polymeric materials used in electronic packaging. There are few candidate polymeric materials for replacing eutectic solder bonding in electronic devices used in high-temperature environments. Most polymeric electrically conductive adhesives are not capable of long term reliability in such environments. We have demonstrated a low-temperature sintering adhesive that, with modification, will address these performance issues. Based on a novel polymeric resin formulation, they are solvent-free and easily processed. A unique combination of alloy powders in this resin formulation allows the preparation of composite adhesives capable of forming metallurgical connections to suitable metal surfaces. These may be optimized to have electrical and thermal conductivity properties similar to solder materials but with the processing advantages of polymeric adhesives.