A Novel High Thermal Conductivity, Low CTE, Low Weight MMC Substrate for Microelectronics Packaging

This Small Business Innovation Research Phase I program proposes the development of a high thermal conductivity (470-550 W/mK), low coefficient of thermal expansion (5-8 ppm/K), and low weight (2.9-4.3 g/cc) Cu based metal matrix composite material to produce high performance substrates for microelectronics packaging. The proposed MMC system uses copper as the continuous metal matrix and cubic boron nitride (CBN) as the discrete second phase. The proposed consolidation process is a net shape process based on the powder metallurgy approach and in-situ infiltration of the copper. Heat sinks produced using this process are net shape as fired, requiring no further machining to meet specifications. The CTE of the material can be match to that of the dice that will be place on top. A closer match to silicon and a very good match to galium arsenide is obtained by adjusting the proportion of Cu to CBN for the composite. In-situ Cu infiltration conditions at relatively low temperature (~1080_C) in a reducing H2 atmosphere result in low processing cost. Cost reduction is also realized by eliminating the need for post-fired machining. The Cu/CBN composite presented in this proposal has better properties than other existing MMC's substrates systems in the market. The Cu/CBN is lighter than Cu/W or Cu/Mo, has better thermal conductivity than Cu/W or Al/SiC, and exhibits a better thermal expansion match to the die than any of them. The proposed technology on Cu/CBN composite material, will provide an excellent alternative for microelectronics packaging where is necessary to insure reliability and long life. The new Cu/CBN material will be applied to the manufacturing of electronic packages for wireless microwave communications packages for RF applications and high power packages. Electronics manufacturing companies such as Raytheon Electronics, and electronic substrates manufacturer such as Brush Wellman, Ceramic Products Division, have already expressed their interest in using and producing this type of MMC substrates