Reliability study of ceramic substrate in a SIP type package

Ceramic substrate reliability in a lead frame based system in package (SIP) is investigated during the assembly process. Ceramic is a brittle material in the temperature range of the assembly process, so its failure mechanism is mainly fracture. Ceramic cracks can be caused either by thermo mechanical or by purely mechanical loads. In this study, only the mechanical impact on the ceramic substrate is investigated during assembly molding process. The effects of both lead frame downset and support pin over-press are studied through the commercial finite element code Ansys. Parametric studies show that the change of the lead frame downset before the assembly molding process has little impact on the ceramic substrate stress. However, the change of the support pin over-press tolerance has a large impact on the ceramic substrate stress. According to these simulation results, effective measures can be taken to control the support pin over-press, to avoid the risk of ceramic substrate failure during the assembly process.