Study Of A Low-silver Lead-free Solder Alloy

For environmental protection and the protection of human health requirements, lead-free electronic products have entered the implementation stage. For reducing the cost of the existing lead-free solder, to improve their requirements of high temperature aging performance, the research for low-silver lead-free solder has a very important significance. A low-silver-based solder SAC0307 is in use, such a high temperature solder alloy has a poor wettability and SAC305 solder alloys are very expensive. For this recearch based on a kind of new low-silver lead-free solder SAC0507X. By comparing the test datas to study the influence of silver content and the X element on solder melting point, wettability and dissolution of copper content and find the best overall performance of the solder alloy composition, and to develop a low cost, low melting point, good wettability, low amount of dissolved copper with excellent properties lead-free solder.Solder melting point of the study results show that: low silver type SAC0507X lead-free solder alloy melting point range is 217.24 ~ 225.970C, basically, the same with internationally recommended high-silver-type Sn-Ag-Cu solder alloy melting point lineWettability of the solder results show that: Because of low silver lead-free solder alloy SAC0307's poor wettability, The SAC0507X increasing the silver content and the addition of alloying element X, the wetting time reduced to 1.293s, has been far from meeting the mechanization of the industrial production of t≤2.5s actual demanded, and such a solder alloy composition of the largest wetting force is 3.687mN, has good wetting properties.Shear stress on the solder joints results show that: low silver lead-free solder alloy SAC0307 shear force is 25.948N, but SAC0507X solder alloy slightly higher than that, the maximum shear force is 28.673N, less than High silver type SAC305 solder alloy.Lead-free solder alloy on the microstructure observation showed that: X alloy elements added will reduce the rate of diffusion of atoms diffuse, refine grains and thus hinder the growth of intermetallic compounds; from the cross-sections of soldered joints can be seen X alloying elements decreases the brittle intermetallic compound growth rate and improve the mechanical properties of joints.