Investigation of the influence of voids on the reliability of LED solder joints by computer tomography and forward voltage measurements

Abstract

Our contribution focuses on the effect of voids on the reliability of solder joints for high-power LED applications. We investigate the reliability of the solder joints with computer tomography (CT) and additional forward voltage measurements to gain a better understanding of the fatigue behavior of solder joints with different void distributions. We characterize low-and high-void solder joints before and after reliability tests, such as thermal shock, by using CT to monitor crack initiation and propagation. In parallel, the forward voltages of the LED are measured and are discussed as an additional indicator for solder fatigue. We compare the results of the CT investigations with results from the forward voltage measurements, and they are contrasted with respect to failure modes, such as the position of cracks.