MicroLEDs provide unrivaled luminance and operating lifetime, which has led to significant activity using devices for display and non-display applications. The small size and high power density of microLEDs, however, causes increased adverse heating effects which can limit performance. A new generation of electrically insulating high thermal conductivity materials, such as alumina, has been proposed to mitigate these thermal effects when used as a substrate as an alternative to glass. This strategy then could be used as a method of passive heatsinking to improve the overall performance of the microLED. In this work, a newly available material, an 80 micron thick alumina ceramic substrate, is shown to yield a 30 % improvement on average in the maximum current drive over a glass substrate.