The effect of NaCl on water condensation and electrochemical migration

The effect of NaCl crystals on water condensation and on electrochemical migration processes (ECM) were investigated in case of different lead bearing and lead-free solder alloys on FR4 substrate during a special Thermal-humidity Bias (THB) test, called dew point test. The dew point test simulated the water condensation process and ECM, which processes were followed by in-situ optically and simultaneously electrically as well. The results showed that NaCl crystals can accelerate the condensation intensity, hence they played role as condensation cores. Furthermore, water droplets have formed locally “water bridges” between adjacent conductor lines. On the other hand, after the dissolution of NaCl crystals the ECM processes were accelerated. Finally precipitates and dendrites were formed resulted in shorts.