Investigation of the Effects of Salt Contamination on Electrochemical Migration of Printed Circuit Boards by Temperature Humidity Bias Tests

Abstract

As the integration development of electronic products, the wiring distance on printed circuit board (PCB) becomes smaller, which increases the potential risk of insulation failure of PCB based on electrochemical migration (ECM) under humid environment. Facing to the severe airborne pollution in China, dust particles containing soluble salts can deposit on the PCB inside the electronic devices to make the ECM failure more complicated, since the soluble salts in the dust can reduce critical humidity to condense more moisture on PCB and can react with the anode to push metal cations formation and migration. Therefore, the effects of soluble salts on insulation degradation extents based on the ECM of PCB need to be studied. In this paper, the ECM failure simulation of PCB contaminated by the soluble salt was carried out by salt solution deposition and drying in advance joint with temperature humidity bias tests. The insulation resistance of PCB contaminated with salt solution of various concentrations was monitored. The ECM process and failure mechanism were analyzed by the detection of the morphology and element compositions on electrodes and corroded products. The time to failure appears as a negative exponential function with the concentration of soluble salt.