Pulse-Shadowing-Based Thermal Balancing in Multichip Modules

Multichip modules (MCM) is the standard solution for high power density in high current applications, which contains a multiple parallel-connected semiconductor devices inside the same package. Due to the limited space and parametric variations, it is not realistic to achieve homogeneous temperature among the devices. This temperature mismatch provokes different thermal stress, thereby reducing the lifetime of the hotter ones. As a solution, this work investigate the pulse-shadowing strategy, applied for the thermal balancing in MCM. Based on junction temperature sensing through a single collector-emitter voltage sensing circuit, the hotter devices are shadowed during specific periods. To validate the temperature distribution among the dies, a finite elements model of a 24-dies MCM is developed and a setup with a 3-chips MCM is constructed. In addition, a case study is carried out to evaluate the impact of the thermal balancing on the reliability and efficiency of MCMs.