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52 SMT Magazine • June 2014 Heat-Dissipating Solutions Many power electronic circuits are built on a technology known as direct-bond copper (DBC), a sheet of alumina or aluminum ni- tride with a piece of copper film bonded to it through a thermal chemical process. Although DBC circuits are ideal for high-current appli- cations, they do have some limitations. These limitations include substrate cracking and met- allization peeling due to thermal mismatch be- tween the substrate and copper layers resulting in thermal cycling reliability failures. This can affect the long-term reliability of the electronic device, especially in high-temperature applica- tions. Design engineers are seeking solutions that can match the thermal expansion of cop- to find electronic components and parts, and the materials used in them, which can with- stand these extreme temperatures that are in- creasing to 175°C and up to as high as 300°C. The oil and gas drilling industry is also look- ing for materials that can withstand high-tem- perature applications. The trend in the drilling industry is to find material sets that can oper- ate at temperatures of approximately 175°C and higher for extended time periods. In downhole drilling applications, electronic sensing devices are inserted in pipes that have been drilled into the earth. The temperatures in these pipes are ex- tremely high, and the electronic sensing circuit- ry must be able to operate properly to send back the signals needed for the drilling operations. feaTure TRenDS In THeRMAL MAnAgeMenT MATeRIALS FOR eLeCTROnIC CIRCuITS continues figure 3: Silver/palladium silver and copper conductive paste materials are designed for hybrid circuits.