Epoxy molding compounds for high temperature applications

There is an increasing trend for High Temperature packaging in Automotive and other applications where microelectronics is found in close proximity of heat sources. Furthermore, with the emergence of GaN and SiC technologies with very high dissipation of thermal energy, packaging will be required to withstand high temperatures. Epoxy Molding compounds are mainstream encapsulants in various packaging technologies. These organic materials will be subjected to steadily higher ambient temperatures, thereby reaching their intrinsic limitations. Currently, a few materials have been qualified to withstand ambient temperatures of up to 175°C. However, the requirements will keep increasing to higher temperatures in the future (e.g. > 200°C). There are a few known and relevant studies in the literature on the behaviour of epoxy molding compounds at temperatures exceeding the known Automotive Grade 0 level of 150°C. Thermal degradation of the encapsulant is manifested by the appearance of cracks on the surface and reduced hermeticity of the package, driven by surface oxidation. This paper will describe a study done on some molding compounds from different classes recommended for High Temperature applications.