Characteristics of environmental factor for electrochemical migration on printed circuit board

This study investigates whether electrochemical migration (ECM) is affected by factors such as the printed circuit board (PCB) material, distance between the conductors, bias voltage, contamination and underfill process under water drop (WD), temperature and humidity bias (THB), and polarization tests. The resistance of ECM with polyimide PCB was greater than that with FR-4 (flame resistant-4) PCB. The ECM rate was increased by decreasing the distance between the conductors of opposite polarity and increasing the bias voltage. The cured underfill on PCB protected the ECM growth, while contamination with chlorine ions accelerated the ECM growth.