Single Side Direct Cooling SiC Module Baseplate Warpage Behavior and Solutions

Single Side Direct Cooling Silicon Carbide (SSDC SiC) is one of the platforms of onsemi VE-Trac™ Family of power modules for EV-traction inverters. It offers a direct cooling with integrated pin-fin baseplate, a Silicon Nitride isolator, a Maximum Junction Temperature (Tvjmax) of 175°C during continuous operation, an automotive grade Silicon Carbide Metal-Oxide-Semiconductor-Field-Effect Transistor (SiC MOSFET) chip technology, Sintered die technology for high reliability performance and compliant to Automotive standard AQG324. One of the major components of the Module is its pin fin baseplate. The baseplate dissipates the peak heat flux found directly underneath electronic components over a larger surface area and provides a stable mechanical base for the power module which can be clamped onto a cooler. The SSDC module will be usually stressed by thermal effects: Ambient conditions (cold in winter nights, hot on summer days) and superpose operation cycles (e.g. stop - driving). The maximum junction temperature at the chip is restricted physically, and the device must be cooled efficiently. This makes the interface between the baseplate and the cooling equipment critical due to the unavoidable bending effects in the modules. This paper talks about the SSDC pin fin baseplate behavior during assembly, its challenges and the solutions implemented to obtain the optimum final warpage.