Particle Prevention During Ultrasonic Welding Process

Abstract:
Ultrasonic welding has been widely adopted in the power semiconductor industry for joining terminals to metallized ceramic substrates. The ultrasonic welding is advantageous in terms of improving the power cycling reliability and production throughput when compared to traditional joining techniques such as soldering [1]. However a primary chal-lenge are the metal particles generated during the welding process. These small sized particles are typically ejected with high velocity and with high temperature during the welding process. If the par-ticles are not completely removed, they will remain inside the power module and might even stick to the chip’s junction termination region. In such cases, they could trigger the breakdown of electri-cal insulation at high voltages at both chip and module level [2]. The process of particle prevention implemented in our LinPak module design [3] is presented in this paper.