Recent progress on the development of Sn–Bi based low-temperature Pb-free solders

Abstract

With the implementation of legislations on inhibiting the usage of Sn–Pb solder in consumer electronic products, Sn–Ag–Cu series solder has been gotten the most application. However, there are some stimulations from electronic manufacturers to adopt low temperature soldering such as the economic driver from the reduction in manufacturing assembly cost and the reliability driver to avoid the dynamic warpage of area array components caused from Sn–Ag–Cu solder. Sn–Bi series solder is one of the promising candidates, which met the requirements for low melting point, low cost and environment friendly. However, the disadvantage of brittleness characteristic prevented its wide practical application. In order to promote the better application of Sn–Bi based solders, many efforts have been made to improve the wettability, mechanical properties and reliability of Sn–Bi based solders. This paper will summarize the related results about Sn–Bi solder alloys from wettability, interfacial reaction, mechanical properties of Sn–Bi solder and reliabilities of Sn–Bi solder joints. Moreover, in order to improve the properties of Sn–Bi solders, researchers have done lots of works on effect of addition of element dopants. The corresponding works of effect of alloying elements on the properties of Sn–Bi solder were also focused. According to the existing research results, it provides an important basis of understanding the current development of Sn–Bi solders.