Effects of Forming Processes on the Microstructure and Solderability of Sn-3.5Ag Eutectic Solder Ribbons as well as the Mechanical Properties of Solder Joints

Microstructure and properties of Sn-Ag and Sn-Sb lead-free solders in electronics packaging: a review

“…The Fig. 27 Typical images of two Sn-3.5Ag solders after spreading experiment: a CRP; b RSP [29] melting behaviors of solder are similar to Sn-Pb solder, which is useful to the continuation of the actual welding measure and equipment [2]. What's more, it can diminish the harm of circuit board components generated by the heat output during brazing.…”

“…Intermetallic spheres of submicron size were observed in the case of rapid solidification. Liu et al [29] observed that the structure of the Sn-3.5Ag solder prepared by the rapid Fig. 3 a Microstructural evolution of Sn-5Ag solder aged at 150 °C, b Energy dispersive x-ray spectroscopy (EDS) analysis of Sn-5Ag [20] solidification process (RSP) is more uniform and finer contrasted to Sn-3.5Ag prepared by the casting-rolling process (CRP), as shown in Fig.…”

“…Some Fig. 4 The electron probe X-ray microanalyzer (EPMA) and element distribution of Sn-3.5Ag solder: a, b, c CRP, d, e, f RSP [29] spherical Sn-Sb IMC and columnar Ag 3 Sn IMC with size of about 15 lm can be found in the grain boundary of Sn-5Sb-1.5Ag solder and the grain interior of the matrix. The same Sn-Sb IMC and Ag 3 Sn IMC were also found in Sn-5Sb-1Ag-1Bi solder.…”

“…Different forming processes will also change the wettability of solder. Liu et al [29] found that the wettability of Sn-3.5Ag prepared by RSP is better compared with CRP. The spreading area of Sn-3.5Ag solder prepared by RSP is 31.8 mm 2 , 31% larger than CRP, as shown in Fig.…”

“…The forming process of solders has influence on the melting point. Liu et al [29] found that contrasted with the CRP, the Sn-3.5Ag solder prepared by the RSP has a lower melting point, the solid phase temperature is reduced by 1.37 °C, and the liquid phase temperature is reduced by 1.44 °C. The main reason is that the grain size of the brazing filler metal prepared by the RSP is smaller, which adds the surface energy and lowers the melting temperature.…”