Diamond can serve well as a heat sink for semiconductors because diamond insulates against electricity, yet it readily conducts heat. Type 2a diamond has a thermal conductivity of 2000 w/m/k, or over five times that of copper. Diamond's coefficient of thermal expansion (cte) closely matches that of sl and gaas, which minimizes thermal stress. Diamond is also rigid, non-contaminating, and chemicallystable. Unfortunately, it's extremely difficult to braze or bond a ceramic, such as a diamond wafer, to a metal substrate. Typically, ceramic-metal joints cannot withstand rapid thermal cycling. Diamond resists wetting by metals and must first be surface coated before bonding. Present coating methods are costly, complicated, and time-consuming, and yet do not provide heat sinks to withstand the mismatch in cte between metal and ceramic, leading to excessive stress between the bonded components. To solve these problems, lintel will microengineer the critical interfacial bonding region. They will apply their tungsten/molybdenum fusion-metallizing method. This method should produce diamond heat sinks that strongly bond to metal substrates. The bond should resist both thermal and mechanical shock. The method allows bonding at mass production rates, opening up applications for diamond heat sinks in defense, automotive, aerospace, and electronics industries. Diamond heat sinks can serve in lightweight, radiation-hard, high performance electronic circuits for use in interceptors, sensors, and datatsignal processing devices for anti-satellite applications. The heat sinks can also find use in gaas microwave power devices, laser diodes, heat-conductive pc boards, and high-density ic packaging. The new bonding method may even permit the fabrication of active diamond semiconductors.
