Selective etching and hardness properties of quenched SAC305 solder joints

Abstract

Purpose The purpose of this paper is to investigate the morphology of intermetallic (IMC) compounds and the mechanical properties of SAC305 solder alloy under different cooling conditions. Design/methodology/approach SAC305 solder joints were prepared under different cooling conditions/rates. The performance of three different etching methods was investigated: simple chemical etching, deep etching based on the Jackson method and selective removal of β-Sn by a standard three-electrode cell method. Phase and structural analyses were conducted by X-ray diffraction (XRD). The morphology of etched solder was examined by a field emission scanning electron microscope. The hardness evaluations of the solder joints were conducted by a Vickers microhardness tester. Findings The Ag3Sn network was significantly refined by the ice-quenching process. Further, the thickness of the Cu6Sn5 layer decreased with an increase in the cooling rate. The finer Ag3Sn network and the thinner Cu6Sn5 IMC layer were the results of the reduced solidification time. The ice-quenched solder joints showed the highest hardness values because of the refinement of the Ag3Sn and Cu6Sn5 phases. Originality/value The reduction in the XRD peak intensities showed the influence of the cooling condition on the formation of the different phases. The micrographs prepared by electrochemical etching revealed better observations regarding the shape and texture of the IMC phases than those prepared by the conventional etching method. The lower grain orientation sensitivity of the electrochemical etching method (unlike chemical etching) significantly improved the micrographs and enabled accurate observation of IMC phases.

Effect of TiO2 nanoparticles on the microstructure, mechanical and thermal properties of rapid quenching SAC355 lead-free solder alloy

“…The grain boundaries operate as barriers to dislocation migration during load application, increasing the solder alloy's mechanical resistance to deformation (Yahaya et al, 2020). Anyway, a typical strain curve was obtained, as shown in Figure 6(b).…”

“…The increase in the hardness value at 0.5 and 1.0 wt.% was mainly because of the strengthening of the grain boundaries by the addition of TiO 2 NPs which coincided with a reduction of the size of the Ag 3 Sn and Cu 3 Sn IMC phases, as shown in Figure 3(c) and 3(e), resulting in more grain boundaries inside the solder matrix. The grain boundaries operate as barriers to dislocation migration during load application, increasing the solder alloy’s mechanical resistance to deformation (Yahaya et al , 2020). Anyway, a typical strain curve was obtained, as shown in Figure 6(b).…”

Influence of cooling conditions on microstructure and mechanical property of Sn-0.3Ag-0.7Cu lead-free solder

“…Lee and Huang [16] reported that tensile strength and hardness of SAC 305 solder increased at faster cooling rates due to the formation of a fine-grained primary Sn-rich phase surrounded by a fine eutectic structure. Yahaya et al [17] documented the presence of Ag3Sn and Cu6Sn5 phases, with faster solder cooling rates showing the highest hardness values due to phase refinement. The microstructure and mechanical properties of solder alloys are greatly influenced by cooling conditions that affect their reliability [16,17].…”

“…Yahaya et al [17] documented the presence of Ag3Sn and Cu6Sn5 phases, with faster solder cooling rates showing the highest hardness values due to phase refinement. The microstructure and mechanical properties of solder alloys are greatly influenced by cooling conditions that affect their reliability [16,17]. Refined grains ensure that the internal structure of solder joints is compact and can effectively resist external pressure, thereby improving reliability [18].…”