Effect of the Surface Morphology of Plated Printed Circuit Board on the Reliability of LED Packages

Abstract

We investigated the effect of the surface roughness of the differently plated printed circuit board (PCB) on the reliability of AlGaInP-based LED packages. The electroless-plated PCB exhibited smoother surface than the electrolytic-plated one. Maximum debonding forces depended on the aspect ratios of hillocks on the plated PCB and voids. Thermo-mechanical maximum stress increased with increasing roughness height. For LED packages with the electroless-plated PCB, thermal resistance (R-th) from junction to PCB was increased by 57.43 K W(-1)after operation at 85 degrees C with 35 mA for 1000 h (reliability test), whereas for LED package with the electrolytic-plated PCB, R(th)from junction to PCB increased by 4.1 K/W. The temperatures of the chip areas of the electroless-plated and electrolytic-plated samples were 91.3 and 85.3 degrees C, respectively, after the reliability test. For the electroless-plated and electrolytic samples, the view angles along the X and Y axes were 144.43 degrees and 142.87 degrees, and 143.23 degrees and 145.58 degrees, respectively, after the reliability test. Unlike the electrolytic-plated samples, the electroless-plated samples experienced 4.8% drop in the lumen maintenance and delamination between the mold resin and PCB after operation under the 60 degrees C/90% relative humidity condition with 35 mA for 1000 h.