Electrochemical migration characteristics of screen-printed silver patterns on FR-4 substrate

We evaluated the electrical reliability of screen-printed silver (Ag) patterns sintered at various temperatures under variable bias voltages. Comb-type patterns were screen-printed onto a flame resistance-4 substrate using a commercial Ag nanopaste (24 nm in diameter, 73 wt% of Ag nanoparticles). The printed patterns were then sintered for 30 min in air at various temperatures ranging from 100 degrees C to 200 degrees C. The microstructures and thickness profiles of the sintered conductive patterns were identified with a field emission scanning electron microscope and a 3-D surface profiler, respectively. In this study, the phenomenon of electrochemical migration was investigated with a water drop test with deionized water. These results showed that the time required by dendrites to bridge from a cathode to an anode was affected by the sintering temperature and applied voltage; when the sintering temperature was 200 degrees C, the time to achieve a short circuit was nearly four times that of the sample sintered at 100 degrees C, and while the applied voltage increased from 3 V to 9 V, the time to reach a short circuit decreased, on average, by 11%.