Fabrication of Al-based metal printed circuit board having excellent heat dissipation characteristics using polyimide/AlN powder and evaluation of thermal resistance of light-emitting diode module

A light-emitting diode (LED) module consists of a chip, a package (PKG) substrate, a printed circuit board (PCB), and a heat sink. The heat generated from the LED chip is dissipated via the PKG substrate, PCB, and heat sink. If the heat generated from the LED chip is not controlled, serious problems occur such as shortening of life, reduction in the optical characteristics, and reduced reliability of the surrounding parts. In this study, a metal PCB was fabricated to improve the heat dissipation characteristics of the PCB of which the heat dissipation efficiency was the lowest in the LED module. For a metal PCB with an Al substrate, whose heat conductivity was excellent, polyimide resin and AlN powder (0, 0.5, 1.0, 1.5, 2.0 wt%) with excellent heat conductivity, were mixed to form an insulating layer rather than the epoxy previously used. An LED module was fabricated and its thermal resistance characteristics were analyzed. As the AlN powder content increased, the heat resistance of the metal PCB decreased. The heat resistance of the metal PCB without AlN powder was approximately 12°C/W, whereas that of the metal PCB containing 2.0 wt% AlN powder was 8°C/W, which showed a lower heat resistance by approximately 30% compared to that of the metal PC without AlN powder.