Effective heat dissipation of high power LEDs mounted on MCPCBs with different thickness of aluminium substrates

摘要

This paper mainly discusses the thermal characterization of high power Light Emitting Diodes (LEDs). The Metal Core Printed Circuit Board (MCPCB) was designed with the aid of the recommended solder pad given in the product datasheet. Aluminium Nitride (AlN) was employed as the dielectric layer. Industrial grade aluminium (grade 5052) was utilized as the substrate material of the MCPCBs. The samples under test were varied in terms of substrate thickness on which the LEDs were mounted. The temperature rise at the junction and junction to ambient thermal resistance of the LEDs was investigated. The device performances were investigated with various substrate thicknesses under different ambient temperature at a fixed current input. The experimental results show that the increase in the substrate thickness greatly improved the thermal and optical performance of the LED packages. There were increments in the percentage of decrease in junction temperature rise and the percentage of decrease in the total thermal resistance which is from 19.8 % to 21.2 % and 15.2 % to 17.2 % respectively. The decreases in wall plug efficiency were reduced from 0.9% to 0.2%. Transient dual interface method was employed to determine the junction to board thermal resistance of the sample.