摘要
以Sn8Zn3Bi为研究对象,采用微合金化方法研究了不同含量的Cu元素对其显微组织、钎料合金与Cu基板钎焊后的界面金属间化合物(IMC)层尺寸及焊接接头剪切强度的影响。结果表明,Sn8Zn3Bi-xCu/Cu(x=0.3,0.5,0.8,1.0,1.5)焊接界面IMC主要为层状Cu5Zn8相。随着Cu含量的增加,界面IMC层的厚度逐渐减小,接头的剪切强度逐渐提高,Sn8Zn3Bi-1.5Cu/Cu接头剪切强度较Sn8Zn3Bi/Cu显著提高。经120℃时效处理后,Sn8Zn3BixCu/Cu(x=0,0.3,0.5,0.8,1.0,1.5)焊接接头剪切强度都明显下降,接头断裂方式由韧性断裂转为局部脆性断裂,但添加了Cu元素的钎料界面IMC生长速度较Sn8Zn3Bi钎料慢,因此Cu元素的添加抑制了界面IMC层的生长。
This paper made the Sn8Zn3Bi lead-free solder alloy as the research object, using the micro alloying method to study the effect of Cu element on the microstructures, the thickness of intermetallic compounds （IMC） and the shear strength of the welding joints of the Sn8Zn3Bi-xCu/Cu（x=0,0.3,0. 5,0. 8,1.0,1.5） lead-free solder alloys on Cu pads. Results showed that the Cus Zn8 phase formed at the interface between the Sn8Zn3Bi-xCu （x=0. 3,0. 5, 0. 8,1.0,1.5） solder alloys and the Cu substrate. The thickness of IMC layers decreased and the shear strength of the welding joints increased gradually with increasing Cu. The shear strength of Sn8Zn3Bi-1.5Cu/Cu welding joint was significantly increased comparing with the SnSZn3Bi/Cu welding joint. After aging at 120 ℃ for 144 h, the shear strength of Sn8Zn3Bi-xCu/Cu（x=0,0.3,0. 5,0. 8,1.0,1.5） welding joints obviously decreased, and the fracture mode of the welding joints changed from ductile fracture to mixed ductile-brittle fracture. But the growth speed of the IMC of the Sn8Zn3Bi-xCu/Cu （x= 0. 3,0.5,0. 8,1.0,1.5） welding joints was relatively slower than that of SnSZn3Bi/Cu welding joints. Therefore, the addition of Cu element inhibited the growth of the IMC layer.
