Sn2.5Ag0.5Cu lead free solder balls with "Ge" and "Ni"

Recently, environmental-friendly products have significantly increased the development of lead free solder material. Some products are already in production and most of semiconductors will be released lead-freely. Among the various lead-free solders, the SnAgCu family of solders has been known as one of the leading candidates for high volume mass-production. However, SnAgCu still has a discoloration issue during ir-reflow and burn-in test, and the market requires stronger solder joint for fatigue bending and impact test due to the mobile electronics. In this paper, the countermeasure with adding "Ge" and "Ni" to prevent SnAgCu solder balls from discoloration is investigated and the optimization(3.0 -> 2.5%) of the weight ratio of "Ag" contents to enhance solder joint for fatigue bending and impact test is studied and reliability test for the optimized Sn2.5AgO.5Cu composition is investigated.