Study of the electrical and thermal properties of a silicone elastomer filled with silica for high temperature power device encapsulation

In order to take the full advantage of the high-temperature SiC and GaN operating power devices, package materials able to withstand high-temperature storage and large thermal cycles are required. However, a survey of the commercially available silicone gels mostly used for power module encapsulation, highlights that this type of materials exhibits a maximum temperature limit for continuous operation of about 260 °C. A slight extension of this temperature range might be obtained by using silicone elastomers with hardness still remaining measurable on the Shore A scale. The aim of this paper is to study a silicone elastomer poly(dimethyl)siloxane (PDMS) with silica fillers, with a specified maximum operating temperature of 275 °C, in order to evaluate its ability for high temperature power device encapsulation. First, the nature and size of the filler microparticles were determined using scanning electron microscopy (SEM) observations coupled with energy dispersive X-ray spectroscopy (EDX) analysis. Second...