A Comparison of the Thermal Performance of Low Cost Substrates for Power Electronics

The continuing trend towards increasingly compact circuitry places rigorous demands on the thermal management of electronic assemblies. The problem is particularly severe in power circuitry with integrated control. A number of advanced cooling mechanisms and packaging methods are available, but for consumer products the cost of these solutions is prohibitive. Traditionally, thermal management has been achieved by the attachment of large metal heatsinks, but this introduces further manufacturing processes during assembly. It is demonstrated that efficient heatsinking can conveniently be achieved through the substrate, due to both improvements in, and shortening of, the conduction paths. When used as the final level of packaging in a hybrid assembly, coated steel substrates offer an improvement in thermal performance, in comparison with alumina. The optimum thermal performance is, however, provided by polymer coated aluminium substrate materials.