High-Reliability Solder Pastes For Automotive Applications Reinforcement

Over the life of a product, electronic assemblies must confront with rapid and extreme temperature changes, vibration and drop, all of which will weaken solder joints reliability and cause product failure. Therefore, the way of looking for high reliability solder alloy has become crucial, and through additional elements additions (such as Ni, Bi…), the improvement in mechanical strength, ductility, and wear resistance can be expected which extend the solder joint life even under harsh conditions. After market research, 4 high-reliability solder pastes with variant alloy composition were selected for comparative reliability investigation tests including the influence of different surface finishes (ENIG and Cu OSP), overall soldering performance, impact to package type (WLCSP, CABGA), shear force degradation, the strength of fatigue resistances (TCT, -40~125C) and mechanical shock (0.5ms, 1500G). And implied that the solder paste D finally with 1.5~2.0 times better characteristic life of mechanical strength compared to other 3 solder pastes. This paper furthermore describes the potential for cost reductions via process and/or material optimizations such as elimination of polymer reinforcement for the package.