Investigation of thermally conductive ceramic substrates for high-power LED application

In this paper, the thermal analysis is carried out by the combination of actual thermal measurement and numerical finite element simulation to investigate insightfully the thermal characteristics of each element in the whole assembly of the LED lighting system (LLS). Based on the thermo/fluid coupled field numerical simulation, the ANSYS¿^,s finite elements are used to model the detailed assembly parts in the high-power LLS. The highpower LLS samples were assembled by soldering the LED-Ceramic package on a copper sheet, which was then attached to an aluminum alloy heat sink using thermally conductive adhesive. Four different ceramic materials: AlN, SiC, LTCC with Ag thermal via and Al₂O₃, were studied as ceramic thermally conductive substrates (CTCS) for the high power LED dies´ packaging. The ceramic sub-mounts were produced by packing multiple LED chips with silicone resin containing phosphors coated on a CTCS. The thermal resistances of ceramic sub-mounts with the same configuration were determined to be 0.1411°C/W for AlN, 0.1778°C/W for SiC, 1.9732°C/W for LTCC with 30 volume% of silver thermal vias, and 2.0262°C/W for Al₂O₃. Results indicate that ceramic materials are very suitable for reducing the thermal management issues for high-power LED lighting applications.