NEW PB-FREE SOLDER ALLOY FOR DEMANDING APPLICATIONS

摘要

The growth and expansion of electronic assemblies in automotive and high power electronics applications is driving the electronics industry to solder alloys that can perform in harsh service conditions. Applications such as high performance LED lighting and underhood automotive require a solder alloy to operate at high temperatures where commonly used SAC305 would be prone to failure. When exposed to high service temperatures and thermal cycling, SAC305 undergoes significant microstructure change, specifically, the coarsening of Ag_3Sn particles, which leads to degradation of mechanical properties and poor creep resistance. To improve reliability of SAC alloys, alloying with Bi, Sb, In, Mn, Ni et al. has been studied and suggested by some researchers. It has been shown that through solid solution and precipitation strengthening mechanisms; high performance solder alloys are achievable. However, one of the main challenges when developing potential new high reliability alloys is the difficulty associated with solderability and manufacturability. The combination of alloying elements needs to be engineered in a way that optimizes both mechanical properties while retaining manufacturability and soldering performance. Hence, in the present study we investigate a new Sn-Ag-Cu-Bi-X solder alloy (X represents micro alloying dopants) with excellent solderability and reliability characteristics. It is demonstrated that the new multicomponent solder alloy with improved thermo-mechanical performance and relatively low melting temperature can be an ideal solder material for harsh and demanding applications.