器件焊端和印制板镀层对混装焊点性能的影响

Effect of component lead and board finishes on property of mixed solder

随着电子产品无铅化的不断推进,在高可靠电子产品组装中,无铅镀层器件与有铅焊料混合装配焊接的情况不可避免。采用正交实验研究四种不同镀层的QFP器件、三种镀层PCB、两种温度曲线和SnPb焊膏的兼容性,并测定焊点的抗拉强度,采用扫描电镜分析焊点形貌。结果表明,在不同镀层器件的混装实验中,Sn和SnPb镀层焊点强度高于NiPdAu和SnBi镀层焊点;对于纯Sn镀层器件,采用有铅工艺温度曲线能够兼容该类器件的焊接;在实验采用的三种镀层工艺中,含铅热风整平工艺对焊接温度曲线的兼容性最好。

With the development of lead-free in electronic products, mixed soldering of lead-free components with SnPb solders is inevitable in high reliability electronic assembly. Compatibilities of two temperature profiles to be employed to solder four types of finishes of QFP components on three kinds of finishes of PCB using SnPb paste were studied by means of orthogonal experiments. The tensile strength of solders was measured and formation of solders was investigated by SEM. Results indicate that solders with pure Sn and SnPb finishes have better strength than that with NiPdAu and SnBi finishes. Components with Sn finish are compatible to SnPb temperature profile. The compatibility of mixed assembly with lead hot air solder leveling surface finish process is better than other two surface finishes in three kinds of the finished processes in experiments.