Package design and development of a low cost high temperature (250°C), high current (50+A), low inductance discrete power package for advanced Silicon Carbide (SiC) and Gallium Nitride (GaN) devices

Abstract

The demands for high-performance power electronics systems are rapidly surpassing the power density, efficiency, and reliability limitations defined by the intrinsic properties of silicon-based semiconductors. The advantages of post silicon materials, including Silicon Carbide (SiC) and Gallium Nitride (GaN), are numerous, including: high temperature operation, high voltage blocking capability, extremely fast switching, and superior energy efficiency. These advantages, however, are severely limited by conventional power packages, particularly at temperatures higher than 175°C and >100 kHz switching speeds. In this discussion, APEI, Inc. presents the design of a newly developed discrete package specifically intended for high performance, high current (>50A), rapid switching, and extended temperature (>250°C) wide band gap devices which are now readily available on the commercial market at voltages exceeding 1200V. Finite element analysis (FEA) results will be presented to illustrate the modeling process, design tradeoffs, and critical decisions fundamental to a high performance package design. A low profile design focuses on reducing parasitic impedances which hinder high speed switching. A notable increase in the switching speed and frequency reduces the size and volume of associated filtering components in a power converter. Operating at elevated temperatures reduces the requirements of the heat removal system, ultimately allowing for a substantial increase in the power density. Highlights of these packages include the flexibility to house a variety of device sizes and types, co-packaged antiparallel diodes, a terminal layout designed to allow rapid system configuration (for paralleling or creating half- and full-bridge topologies), and a novel wire bondless backside cooled construction for lateral GaN HEMT devices. Specific focus was placed on minimizing the cost of the materials and fabrication processes of the package components. The design of the package is discussed in detail. High temperature testing of a SiC assembly and electrical test results of a high frequency GaN based boost converter will be presented to demonstrate system level performance advantages.