热时效和焊点尺寸对SnAgCu微焊点强度的影响

针对高度为100～300μm的无铅钎料Sn-3.0Ag-0.5Cu微焊点,研究了等温热时效和焊点尺寸对其在100℃下拉伸强度的影响。结果表明,保持焊点直径不变时,高度为100,200和300μm微焊点未经热时效的平均拉伸强度分别为53.75,46.59和44.38MPa;热时效时间延长使微焊点内钎料合金显微组织明显粗化,导致焊点拉伸强度降低,前述三种高度的微焊点96h热时效后平均拉伸强度分别为44.13,38.38和33.48MPa,但96h热时效对IMC厚度无明显影响。

Effects of isothermal aging and joint size on the strength of Sn-3.0Ag-0.5Cu microscale solder joints

The effects of isothermal aging and joint size on the tensile strength of Sn-3.0Ag-0.5Cu microscale solder joints measured at 100 ℃ were studied. The results show that the tensile strength of Sn-3.0Ag-0.5Cu microscale solder joints is significantly affected by both the joint height and isothermal aging. The tensile strength of joints without aging is found to increase with decreasing joint height. This is because that the effect of mechanical constraint within the solder joint becomes more significant with decreasing joint height. Before isothermal aging,the tensile strengths of joint with a height of 100,200 and 300 μm are 53.75,46.59 and 44.38 MPa,respectively. On the other hand,the tensile strength of joints decreases with increasing isothermal aging time,as the microstructure of Sn-3.0Ag-0.5Cu solder is coarsened by isothermal aging. After 96 h isothermal aging,the tensile strengths of joint with a height of 100,200 and 300 μm are 44.13,38.38 and 33.48 MPa,respectively. However,the isothermal aging has little effects on the thickness of intermetallic compounds.