S含量及时效对Cu/Sn-8Zn-3Bi-xS/Cu钎料焊点可靠性的影响

Effects of S content and aging on reliability of Cu/Sn-8Zn-3Bi-xS/Cu solder joints

研究了S含量和时效对Cu/Sn-8Zn-3Bi-xSi/Cu钎料焊点可靠性的影响,采用润湿铺展面积评价Sn-8Zn-3Bi-xS钎料在Cu基板上的润湿性;通过搭接焊方法制备Cu/Sn-8Zn-3Bi-xS/Cu焊点,研究其90℃时效不同时间的力学性能;采用配有能谱的扫描电镜(SEM)对焊点断面形貌和成分进行观察和分析;采用X射线衍射仪(XRD)对焊点界面形成的金属间化合物进行物相分析。结果表明,添加S能够改善Sn-8Zn-3Bi-xS钎料在Cu基板上的润湿性,S含量为0.05wt%时润湿面积最大。时效时间相同时,钎料剪切强度随S含量的增加先增大后减小,S含量为0.05wt%时钎料具有最大的剪切强度;S含量相同时,钎料剪切强度随时效时间的延长先增大后减小,时效时间为4 h时剪切强度最大。添加S不改变焊点界面金属间化合物的成分组成。

Effects of S addition and aging on the reliability of Cu/Sn-8Zn-3Bi-xS/Cu solder joints were investigated.The wettability of the solder was evaluated by spreading area on Cu substrate.The Cu/Sn-8Zn-3Bi-xS/Cu solder joints were prepared by lap welding and the mechanical properties of the solder joints aged at 90℃for different time were measured.The morphology and constituents of the fracture surface of the solder joints were observed by scanning electron microscopy(SEM),and the intermetallic compounds formed at the interface of the solder joints were identified by X-ray diffractometer(XRD).The results show that the wettability of the Sn-8Zn-3Bi-xS solder enhances by the addition of S,and the optimal S content is 0.05wt%.When the aging time is the same,the shear strength of the solder joints increases first and then decreases with the increase of S content and reaches the maximum value when the S content is 0.05wt%.When the S content is the same,the shear strength of the solder joints increases first and then decreases with the increase of aging time.When aging time is 4 h,the shear strength is the maximum.Addition of S does not change the composition of intermetallic compounds at the solder joints interface.