Doubling the output of automotive LED headlight with efficient cooling using Thermal Pyrolytic Graphite

Abstract

Changing from incandescent or high intensity discharge automotive headlight to LED presents a great thermal management challenge. With thermal conductivities ranging from 120 to 400 W/m-K, aluminum and copper based heat sinks limit the maximal power loading to LEDs. On the other hand, Thermal Pyrolytic Graphite (TPG), which contains millions of highly-oriented stacked graphene planes, exhibits excellent in-plane thermal conductivity (>1500 W/m-K) and very low density (2.25g/cm3). TPG-metal composites can simultaneously achieve high thermal conductivity from the TPG core and high mechanical strength from the metal shell. The benefits of integrating TPG material into automotive LED headlight were investigated in this study for the first time. Design and power configuration of an aftermarket LED headlight was used as the baseline. Thermal simulation successfully predicted the performance of each prototype heat sink, which facilitated the design iteration. Our bench tests on the prototype headlights revealed: a. Replacing aluminum fins with metallized TPG plates reduced total system thermal resistance by 27%; b. Inserting a TPG core underneath LED dies achieved another 24% thermal resistance reduction. The final integrated assembly demonstrated that 2x of the power can be loaded to the LED with TPG material assisted heat dissipation at these two strategic locations.