Comparison of SAC and new Pb-free solder alloy for special application

Abstract

Solder alloy plays a crucial role in the production of electronics devices. Sn-based alloy containing other elements like Pb, Ag and Cu has been the mostly used solder material of electronic circuit in recent years. However, environmental and health concerns over lead toxicity has resulted in recent legislation to limit the use of lead-based solders. Assemblies that work in harsh environment, such as automotive, aerospace, and military have benefited from exemptions for long time. Now due to industry conversion from SnPb to lead free interest in novel solder materials can be observed. Nevertheless, most of these exemptions have expired, and the limited availability of SnPb compatible components have now forced most of these industries into using lead free solders and components. Additionally, the evolution and expansion of electronics into more harsh operating environments, forces the solder alloys to perform more critical functions. This encouraged researchers to discover new leadfree solders. Great amount of effort was dedicated by previous researchers in developing new environmental friendly lead-free solders, such as Sn-Ag- Cu (SAC). Another candidate elements to include in a low melting point lead-free solder include Bi, Au, Tl, Ga, Zn or In.In this paper, the comparison of SAC alloy and new Pb-free solder alloys containing elements such as Bi, Ni and Sb was reported. Their technological properties was compared based on the tests results such as slump test, wetting test as well as spread test. Theoretically, elements contained in the new Pb-free solder alloy offer some benefits. For example, presence of bismuth limits formation of intermetallic compounds between copper surface and tin based alloy. The obtained tests results can be used in the electronics industry for the production of printed circuit boards, in particular for the production of devices for special applications.