Creep corrosion is a common mode of corrosion-related failure. It occurs when metallization corrodes and the corrosion products migrate across printed circuit board (PCB) surfaces, causing electrical short circuit failures when they bridge neighboring features on PCBs.
Creep corrosion is not a new phenomenon, but it has become a greater reliability concern in recent years for two reasons. First is the elimination of lead from electronics. Lead-based solders and surface finishes provided excellent corrosion resistance. However, the higher melting temperatures of lead-free solders and the poor wetting of copper metallization on PCBs forced changes to PCB laminates, surface finishes and processing temperature-time profiles. These changes resulted in a higher risk of creep corrosion on PCBs.
Second, the electronics market has expanded significantly in regions such as Asia where the environments, often humid and with high levels of sulfur-bearing pollution, have a high propensity for creep corrosion.
Creep corrosion is a common mode of corrosion-related failure. It occurs when metallization corrodes and the corrosion...