Thermal characteristics for chip on metal package of LED lighting module

Abstract

The insulator of the metal printed circuit board (PCB) area layer, where a chip is packaged in the metal PCB structure of the chip on board (COB) package, is removed in order to propose a chip on metal (COM) package that allows the direct packaging of the chip to the PCB metal layer. In order to analyze the thermal characteristics from the chip, both COB and COM packages were fabricated during the operation to measure the chip junction temperatures (Tj) and thermal resistances of both specimens. According to the Tj measurement result, Tj=34.64°C for the COM package with the removed insulator and Tj=45.28°C for the COB package, showing that the COM package had an approximately 10°C less thermal distribution. Similarly, the thermal resistance of the COM package was 0.7°C/W, which was about 1°C/W less than the COB package thermal resistance of 1.67°C/W. Also, by comparatively analyzing the changes in the spectrum, color coordinates, and speed of light according to the driving time, it was found that luminous color stabilization may have contributed to the luminescence properties of the COM package, which has lower thermal resistance, and the degradation of the chip and packaging material can be minimized.