Property-Performance Relationships for Sustained High Temperature Operation of Electronics

Much of the electronics used to support power systems, and enable safety systems resides underhood where operating temperatures are much higher than in traditional consumer applications. Underhood electronics may be subjected to sustained temperatures of 125-150C for prolonged periods during operation. Majority of the available plastic encapsulated electronic components are designed for operation at a much lower operating temperature, often in the neighborhood of 55-100C and lower expected design lifetimes in the neighborhood of 3-5 years. Electronics content has increased on the automotive platform owing to the emergence of advanced driver assistance systems and stricter fuel consumption standards. The migration to hybrid- electric vehicles (HEV), and full-electric vehicle (FEV) platforms has further enhanced the role of electronics on the automotive platform. Packaging solutions that can operate at 150-200C for sustained periods are scarce. In this paper, process-property- performance relationships have been characterized for a number of packaging materials including underfills and electronic mold compounds under sustained operation at high temperatures. Changes in material properties were studied for isothermal aging at three different temperatures which are above, near, and below the glass transition temperature of the material. Long-term exposure of four different underfill materials were investigated at three different isothermal aging temperatures. A fabrication method has been developed to prepare test specimen for DMA testing. The properties of underfill materials including storage modulus, loss modulus, glass transition temperature and tangent delta have been studied using a combination of dynamic mechanical analysis and tensile testing. Material-based control indicators have been identified for each of the materials.