Structural, Thermal and Wetting Characteristics of Novel Low Bi-Low Ag Containing Sn–x.Ag–0.7Cu–1.0Bi (x = 0.5 to 1.5) Alloys for Electronic Application

Abstract

Low drop failure tendency and reduced cost of low silver SAC alloys has provoked researchers to exploit their potential for portable electronics. Low Bi addition in near-eutectic SAC alloys has proven confinement of IMC layer. In order to exploit potential of Ag variation (0.5–1.5 wt%) on structural, thermal, wettability and IMCs layers growth during thermal aging in low Bi-low Ag, Sn–xAg–0.7Cu–1.0Bi alloys were investigated. The resulting microstructure were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Furthermore, structure–property correlations were established. This study signifies that 1.5 wt% Ag is responsible for lower melting point (220.18 °C) and lower contact angle (33°) in low Bi-low Ag, Sn–xAg–0.7Cu–1.0Bi alloys. Moreover, increment in Ag content restricted the interfacial IMC layer growth during thermal aging making them reliable for use in portable electronics. The microstructural investigations inferred that 0.5 wt% Ag solder joint with Cu substrate had the highest growth rate (0.34 μm/h1/2) of IMC layer thickness while 1.5 wt% Ag solder joint had lowest growth rate (0.17 μm/h1/2).