Effect of dust pollution on temperature characteristics of electrochemical migration

As demand increases for light, thin, small and multi-functional electronics, printed circuit board (PCB) are developing towards further integration and miniaturization, which unfortunately leads to greater sensitivity of PCB to electrochemical migration (ECM). Environmental pollution causes the contamination of PCB in the electric devices, especially the deposition of dust particles. The surface humidity of PCB can be increased due to the coverage of dust, which changes the ECM conditions. In this paper, the effect of dust particles on the temperature and the time to failure (TTF) of ECM of PCB was studied by simulation experiments. The comb pattern PCB and quartz particles were used to simulate the contaminated PCB under temperature humidity bias (THB). The effects of various ambient temperature and distribution density of particles on TTF of PCB were compared. The experimental results showed that the relation between TTF and temperatures appeared as Arrhenius equation when the PCB had no dust or was covered by low density of dust particles. However, as distribution density of particles increased to 1050μg/cm
²
and even more, the relation between TTF and temperatures no longer met Arrhenius equation, which was caused by the absorption of moisture by particles deposited on PCB.