CMA Substrate for Power Semiconductor Packaging

DBC substrate is a critical component in the high power semiconductor modules used in hybrid, plug-in hybrid, and fuel cell vehicles. The substrate, which is used for battery management and motor control, greatly affects the cost and reliability of these modules. Because of the large difference of thermal expansion between copper and ceramic substrates, the ceramic substrate in DBC is prone to cracking when subjected to multiple temperature excursions. The root cause of this problem is the large residual thermal stress in the ceramic substrate, imparted by copper metallization during bonding. This project will develop an alternative CMA substrate that will have significantly lower residual thermal stress. The reduced thermal stress means that the reliability of the new substrate will be ~2-3 times better than that of alumina DBC. The CMA substrate will have a thermal conductivity greater than 200 W/m K and a coefficient of thermal expansion less than 7 ppm/°C, which will vary with the thickness ratio of its constituents. Commercial Applications and other Benefits as described by the awardee: The CMA substrate should help enhance the reliability and lower the cost of hybrid electric vehicles. The substrate also should find use in the packaging of solid state laser diodes and high brightness LEDs.