Cu基板退火处理的Cu/Sn58Bi/Cu钎焊接头界面微结构

Study of interfacial microstructure of Cu / Sn58Bi / Cu solder joints with annealed Cu

研究了铜基板退火处理对Cu/Sn58Bi界面微结构的影响.结果表明,在回流以及时效24 h后Cu/Sn58Bi/Cu界面只观察到Cu6Sn5.随着时效时间的增加,在界面形成了Cu6Sn5和Cu3Sn的双金属间化合物(IMC)层,并且IMC层厚度也随之增加.长时间时效过程中,在未退火处理的铜基板界面产生了较多铋偏析,而在退火处理的铜基板界面较少产生铋偏析.比较退火处理以及未退火处理的铜基板与钎料界面IMC层生长速率常数,发现铜基板退火处理能减缓IMC层生长,主要归因于对铜基板进行退火处理能够有效的消除铜基板的内应力与组织缺陷,从而减缓Cu原子的扩散,起到减缓IMC生长的作用.

The effect of annealed Cu substrate on the microstructure of solder joints was investigated. Experimental results showed that only scallop-shaped Cu6Sn5 was observed at the interface of Cu / Sn58 Bi / Cu after reflowing and aging for 24 h. A bi-layer structure consisted of Cu6Sn5 and Cu3Sn was formed at interface and the thickness of IMC layers increased with the increase of aging time. With the long aging process,Bi particle segregation was producedat the interface of solder joint of un-annealed Cu substrates. However,Bi particle segregation was hardly observed at the interface of solder joint of annealed Cu substrates. Compared with the growth rate constants of IMC layer of interface of annealing and un-annealing Cu and solder,it was demonstrated that annealing treatment on Cu substrate could effectively retard the growth of interfacial IMC layers,it mainly attributed to that the annealing treatment on Cu substrate could effectively eliminate inner-stress and defects,reducing the diffusion of Cu atoms and retarding the growth of IMC.