Electrochemical migration characteristics of eutectic SnPb solder alloy in printed circuit board

The smaller size and higher integration of electronic components result in smaller gaps between metal conducting layers in an electronic package and printed circuit board (PCB). Under high temperature and humidity, electronic components respond to applied voltages by electrochemical ionization of metal and the formation of a filament, which leads to short-circuit failure of an electronic component, which is termed electrochemical migration (ECM). In this study, a four-layered PCB with SnPb electroplated through-hole-via was used to determine the ECM characteristics of a eutectic SnPb (63Sn–37Pb, weight percent) solder at a temperature of 85 °C, a relative humidity of 85%, and DC bias voltages between 75 and 100 V. Additionally, polarization tests for the solder materials were carried out to determine ECM characteristics. Pb was found to be more susceptible to polarization than Sn, which matched the composition distribution of the conductive anodic filament on the PCB surface.