A quick electrical inspection method of solder joint quality for LED products

Abstract

Solder joint qualities of light-emitting diodes (LED) lamps have a significant effect on their lifetime. Due to variations in LEDs, the product lifetime is determined by the lowest performing component of the product when multi-LEDs are used. In this paper, we propose a quick electrical inspection method of solder joint quality for LED products, which is obtained by the heating curve measurement for a short time with the forward voltage as a temperature sensitive parameter. The utility of this quick inspection method is verified by the measurement of a solder voids ratio based on the most commonly used approaches in the industry-x-ray. The proposed method is cost effective and only needs around 1-5 s for each LED, which is about one third of the x-ray. Therefore, the quick electrical test method is both meaningful and promising especially when carrying out quality tests on large quantities of solder and can be a highly recommended method to be adopted by the LED lighting industry.