High brightness LED assembly using DPC substrate and SuperMCPCB

This paper is to evaluate the thermal performances of a Direct Plated Copper (DPC) substrates attached on a high performance MCPCB thermal board for high brightness LED (HBLED) applications. The advantages of DPC substrate compared to traditional Direct Bond Copper (DBC) substrate include: more robust bonding between the substrate and copper metallization, ability to offer substrates with a wide range of copper thicknesses including thin copper for fine patterning, excellent electrical and thermal contact between copper plated vias and surface metallization and lower temperature processing which means much reduced residual stress in the copper metallization layers and copper/substrate interface. The high performance MCPCB in this study has a unique structure, in which an integrated metal post is located directly underneath the LED device providing an effective thermal path for the assembled device. In addition, as this metal post is an integral part of the heat spreader, resin/metal delamination concern associated with most conventional MCPCB can be avoided and therefore provides the highest possible long-term reliability, especially when lead free solders are used as device attachment materials. Using this DPC substrate and high performance MCPCB combined structure, it was established that the performances of LED devices can be greatly improved. Investigations were conducted to establish the compatibility of the high performance Direct Plated Copper (DPC) ceramics substrate (AI₂O₃ and A1N) assembled on this improved thermal board structure and the findings will be presented in this paper.