In this paper, an automotive power module (APM) package is considered with multiple die including MOSFETs, passive components, shunt resistor and thermistor attached on the direct bonded copper (DBC) substrate. 3D finite element models for design and assembly process are generated in order to conduct the DoE numerical simulations for each design and assembly process. In design phase, both electrical and thermal simulations are carried out to improve the electrical and thermal performance. The electrical resistance and inductance are examined in order to minimize the package effects on Rds(on) and switching noise. Thermal characterization is conducted for the APM heat dissipation design evaluation. In assembly manufacturing process, molding is a very critical process to ensure the high reliability of the APM product. Molding simulation is discussed to check the flow front, gate design option and the possible voids track. The mechanical simulation is also conducted to check the warpages and stresses after molding and the APM mounting process to see if package cracking, or delamination might occur in these assembly processes. Modeling is conducted to determine the proper clamping force for low clearance and avoid high stress in ceramic.
IntroductionAutomotive power module (APM) technology is one of the fastest growing areas in power semiconductor industry due to the rapid advances in power integrated circuit (IC) fabrication and the demands of a growing market in automotive industry, especially for electric vehicle (EV) and hybrid electric vehicle (HEV) areas [1][2]. The design rules and material and structure layout of power packaging are quite different from regular memory and digital IC packaging. Due to the intrinsic high current density and high operation temperature, the performance requirements for APM are extremely high, especially in handling harsh thermal and electrical environments [3].To reduce cost and improve time to market, electrical, thermal, molding flow and mechanical modeling and simulation are applied to investigate the electrical, thermal, molding and reliability performance in each design phase and assembly process of an advanced APM. In our previous efforts in assembly process, the air vent and its effect on molding process was studied [4]; Die thinning process was investigated for a power system in package (SiP), the parameter analysis and reliability study for a power SiP design were presented [5-6]. However, there seems few work on the systematic evaluation for an APM design and assembly process. In this paper, an APM is investigated with multiple