Effect of Copper additions on Su-Cu lead free solder alloy

Abstract

Change towards microstructure and mechanical properties of Sn-Cu solder alloys when the Cu composition was added has been studied. In this research, three copper composition Sn-0.7%Cu, Sn-4%Cu and Sn-10% Cu were used. These samples were melted in a furnace in two different melting temperature which is 250℃ and 500℃. The solder alloys also were melted in a furnace and were joined on a Cu substrate. The solder joint between the solder alloys and the Cu substrate has been observed under scanning electron microscope and Cu6Sn5 and Cu3Sn phase has been identified. Scallop-shaped Cu6Sn5 were also has been observed at the interfacial IMC layer at the solder joint. Different Cu composition has changed the morphology on the surface of the bulk solder and also the thickness of the IMC layer. Micro-hardness test and phase analysis also has been done on the six bulk solder. The thickness of IMC layer of the solder joint increased upon addition of Cu composition in the Sn-Cu solder alloy. Micro Vickers hardness testing for bulk solder alloys shows that at high melting temperature, the microhardness value of bulk solder increased upon addition of Cu composition.