Shear strength of joints made of lead-free solders

This paper presents results of mechanical testing of soldered joints made of widely used lead free solder and most popular lead containing one. Measured parameter is shear strength. Tested solders were lead-free Sn-3,8Ag-0,7Cu and lead containing Sn-37Pb. With those solders set of SMD resistors was mounted on pads made of copper and copper electrolytic covered with nickel layer. As mechanical ruggedness of soldered joint strongly depends on presence of intermetallics compounds samples were treated to heat 150°C 250 and 500 hours and shear strength was measured subsequently and values were compared to ones non thermal aged. Thickness of intermetallics compounds and its influence to shear strength was investigated.