Voiding in lead-free soldering of components with large solder pads

摘要

The paper presents the quantification of void formation in lead-free solder joints underneath bottom terminated components (BTCs) through X-ray inspection. Experiments were designed to investigate how void formation is affected by using vacuum in reflow soldering on the example of light emitted diode (LED) packages on metal core printed circuit boards (PCBs). Convection and vapour phase reflow soldering were used for LED assembly. X-ray inspection system analyzed the statistical distribution, mean value, standard deviation and process capability value Cpk of thermal pads coverage for various technological versions of LEDs.