Process Development of Silver Sintering for EV Power Module Attachment
Andrew Hofmann and Rodolfo Silva Melo
Advisor: Roderick Mapanao (Jabil Inc.)
Process Development of Silver Sintering for EV Power Module Attachment
Andrew Hofmann and Rodolfo Silva Melo
Advisor: Roderick Mapanao (Jabil Inc.)
Sintering is a solid-state bonding process where silver particles bond together via a diffusion mechanism under applied pressure and controlled temperature, forming a dense, high strength and high thermal conductivity joint without melting the material. This process can be used to create a bond between a power module and a heatsink that has strong mechanical properties and high thermal conductivity. This attachment process is currently being explored in use cases such as in EV inverter assemblies as a preferred method of power module attachment. This is due to the increased reliability and performance of sintered bonds compared to traditional soldered bonds. The existing knowledge fails to address the initial stages in the sintering process. These include paste mixing, screen printing, module pick and place, and drying. Also, the existing knowledge does not address sintering in a high-volume manufacturing environment where cycle time is critical. The purpose of our project was to develop the pre-sintering process methods for silver sintering, and to find the specific sintering parameters (pressure and temperature) that more closely align with those of a high volume manufacturing setting, where lower cycle times are better. After finding the ideal processing methods for the pre-sintering process, our project varied the temperature and pressure of sintering amongst samples and analyzed the resultant shear strength using both a torque setup and Instron, thermal conductivity using a thermoelectric cooler, and the microstructure and porosity using CSAM. Our study recommended the sintering temperature and pressure that resulted in the best performing bond while considering the use case of a high-volume manufacturing process.