Wettability, Microstructure, and tensile properties of Sn- 3.0Ag-0.5Cu solder alloy prepared by reflow oven and susceptor-assisted microwave

Abstract

A susceptor-assisted microwave (SAM) has been recognized as one of soldering methods for lead-free solder alloys. In this study, the effect of the soldering method on the wettability, microstructure, and tensile properties of the Sn3.0Ag0.5Cu (SAC305) solder alloy were investigated. The SAC305/Cu was reflowed using a conventional reflow oven (SAC305-O) and a SAM (SAC305-H40) heating. The wettability was measured by the wetting angle and the spreading ratio. The morphology and composition of the intermetallic compound (IMC) joint were evaluated on top-surface and cross-sectional views. The ultimate tensile strength (UTS) was characterized at a maximum load of 5 kN and a crosshead speed of 1 mm min-1. The results indicated that wetting angle and spreading ratio for SAC305-O (30.94°, 86.63%) and SAC305-H40 (18.60°, 92.20%) had a sufficient requirement on the wettability. The top-surface (round shape) and crosssectional (scallop-shaped) morphologies of SAC305-H40 exhibited smaller grain sizes and thinner (2.47 μm) IMC layers at the solder joint compared to those of SAC305-O (3.65 μm). Compositional analysis confirmed that the observed IMCs consist of Cu6Sn5, Ag3Sn, and Cu3Sn for both samples. The UTS of SAC305-H40 (43.75 MPa) was greater than that of SAC305-O (31.30 MPa). The SAC305-H40 had a 28% reduction in the IMC layer thickness and a 29% increase in the UTS compared to that of SAC305-O. From the findings, the SAM method had a remarkable performance and had a potential as a replacement for the conventional method.