Dielectric Properties and Partial Discharge Inception Voltage of Aluminum Nitride Insulating Substrate at High Temperatures

Recently, as power modules tend to have higher output density, large-capacity and downsizing of the module are demanded. When the power module is operated at higher temperatures, evaluation of high temperature electrical properties of the power module becomes important. However, there are very few reports on the high temperature insulation properties of the ceramic insulating substrate for application of power module. This paper presents dielectric properties of ceramic insulating substrates consisting of aluminum nitride (AlN) used for power module up to high temperature of 450 °C. Besides, partial discharge inception voltage (PDIV) of the ceramic substrate without encapsulation is also measured at high temperatures to 250 °C in air. Thus obtained results are discussed with the temperature dependence of the permittivity and ac conductivity of the ceramic substrate considered.