时效处理对CuCrSnZn/SnAgCu钎料接头界面及剪切性能影响

为了探讨引线框架铜合金与无铅钎料钎焊接头界面性能,采用扫描电镜及万能材料实验机,分析了引线框架用CuCrSnZn合金与SnAgCu系无铅钎料钎焊接头,在160℃时效不同时间的过程中界面形貌及接头剪切性能的演变过程.结果表明,时效前,钎焊接头界面处形成了一层长针状的Cu6Sn5；不同时间时效处理后,接头界面IMC层厚度有不同程度的增加,Cu6Sn5变长变粗,逐渐离开界面进入钎料内部,靠近铜合金片材基体的一侧会出现极薄的一层Cu3Sn层.无铅钎料钎焊接头时效25h剪切强度可到27.3 MPa,其后逐渐降低.未时效、时效25 h和50 h断裂发生在钎料基体内部,时效至300 h,断裂位置向界面金属间化合物处转移,剪切断口断裂形式逐渐由韧性断裂向脆性断裂转变.

Effect of aging treatment on the microstrucure and shear property of a CuCrSnZn and SnAgCu brazed joint

The microstructure and shear property of a CuCrSnZn and SnAgCu brazed joint under 160 ℃ thermal exposure conditions were investigated by means of an electron scanning microscope and universal material machine.The results show that the long thin needle interface layer is the Cu6Sn5 layer before aging treatment.With an increase in aging time the thickness of intermetallics at the interface was increased;the Cu6Sn5 scallop was lengthened and coarsened and finally moved to solder.There is also a small amount of Cu3Sn close to the copper alloys side,and the shear strength of the joint slightly increases at the initial stage of aging and to 27.3MPa when aging for 25 h,then decreasing gradually after aging for 25 h.It displays an excellent welding property.The fracture takes place inside the solder matrix at the initial stage of aging.After aging for 300 h,the position of fracture gradually moves to the interface while the fracture type gradually changes from a ductile fracture to a brittle fracture.