Investigation of silicon-based light emitting diode sub-mounts: Enhanced performance and potential for improved reliability

Abstract Aluminum nitride (AlN) and aluminum oxide (Al2O3) ceramic light emitting diode (LED) sub-mounts are the most widely used package substrate for recently-developed high-brightness (HB) LED package applications because they exhibit superior thermal conductivity compared to conventional printed circuit board (PCB) package substrates. Nonetheless, the Al2O3 ceramic sub-mount exhibits thermal conductivity in an unacceptable range, and manufacturing the AlN ceramic sub-mount is problematic due to high material cost and difficult processing. Wafer-level packaging (WLP) technology has shown noticeable improvements in manufacturing and silicon exhibits outstanding thermal conductivity. Thus silicon might become an alternative package substrate for HB LEDs. This research studied the feasibility of replacing conventional ceramic sub-mounts with WLP LED sub-mounts. The performance features of thermal dissipation, insulation, and high temperature reliability of LED sub-mounts with variable SiO2 thickness were analyzed and compared to the results obtained from conventional Al2O3 and AlN ceramic sub-mounts. Experimental results show that silicon LED sub-mounts lead to better thermal dissipation performance than do Al2O3 ceramic sub-mounts, and the results also reveal acceptable insulation performance and high temperature reliability for silicon sub-mounts.