The soldering properties of SAC305/CU by microwave hybrid heating
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Date
2019-05
Authors
Pauline Kong Swee Kei
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Abstract
The objective of this research is to study the effect of temperature mode and reaction time of SAC305 solder alloy reflow using domestic microwave hybrid heating method. The structural and elemental characterization confirmed the typical phases present such as β-Sn, Ag3Sn, Cu6Sn5 and Cu3Sn at SAC305/Cu interface. The morphology of intermetallic compound (IMC) displayed increase in thickness when reaction temperature and time increased. Wetting analysis was characterized using contact angle between SAC305/Cu and spreading area. Solder joint with high contact angle and low spreading area indicated reliable solder joint due to its good wettability. Tensile test was conducted to investigate the ultimate tensile strength (UTS) of solder joint. The solder joint reflowed at medium mode for 90 s (M90) gave optimum result as it displayed highest UTS value (37.57 MPa) that can be correlated to its highest contact angle (30.83 °) and lowest spreading area (13.62 mm2). While, solder joint reflowed at high mode for 30 s (H30) had the lowest UTS (21.07 MPa). Fractography analysis of solder joint after tensile test was performed to study the behaviour of fracture surfaces. The transition of fracture mode from ductile mode to mixed ductile-brittle mode occurred as reaction time increased. No IMC was detected on the fracture surface of solder joint which indicated the solder joint did not break at the brittle IMC layer.