GaAs Diode Rectifier Power Module in Mixed Ag- and Large Area Cu-Sintering Technology for Ultra-Fast and Wireless Electric Vehicle Battery Charging

This paper describes the properties of GaAs PIN power diodes and demonstrates their utilization in a 650V 10kW LLC converter for fast charging of electric vehicles. The module comprises two SiC MOSFET half-bridges equipped with Rohm S4101 MOSFETs and the GaAs rectifier module packaged in an EconoPACK2 housing. The SiC half-brides and the GaAs rectifier are assembled on 0.38 mm thick zirconia-toughened alumina (ZTA) substrate with a bending strength of 700 MPa and a thermal conductivity of 27 W/mK. The SiC and GaAs semiconductors are silver-sintered onto a 0.3 mm measuring copper thick film layer on the top and bottom side of the substrate. The substrate is pressure sintered by a novel low temperature copper paste to the three mm thick copper base plate. The bow of the base plate with copper sintered substrates measures 200 μm and is comparable to the bow of soldered substrates. The thermal resistance of the GaAs module is calculated to 0.73 K/W. First electrical measurement at an output power of 0.5 kW reveal the extremely fast switching characteristic of the diode, which were validated by double pulse measurements.