Behaviour of electrochemical migration with solder alloys on printed circuit boards (PCBs)

Purpose This study seeks to investigate the electrochemical migration (ECM) behaviour of printed circuit boards (PCBs) with Sn‐37Pb and Sn‐3.0Ag‐0.5Cu (wt.%) solders under various factors such as the distance between the electrodes and bias voltage. Design/methodology/approach This study investigated the ECM phenomena with different surface finishes of Sn‐37Pb and Sn‐3.0Ag‐0.5Cu solders using water drop (WD) and temperature and humidity bias (THB) tests. After the WD and THB tests, the dendrite phase was identified using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Findings The ECM resistance of the conventional Sn‐37Pb alloy was lower than that of the Pb‐free Sn‐3.0Ag‐0.5Cu alloy. The dendrites grew at the cathode electrodes on the PCB and expanded to the anode electrode. The main elements in the dendrites on the Sn‐37Pb and Sn‐3.0Ag‐0.5Cu finished PCBs were tin and lead, respectively. Originality/value This study evaluates the ECM phenomena of representative solder alloys on PCBs.