高强Cu/Al接头用的Zn基钎料及Cu表面镀层研究

Study on Zn-Based Solder for Cu/Al Joint with High Strength and Coating on Cu Surface

铜铝接头被广泛应用于电力电子等行业。在长期运行过程中,铜铝接头易出现脆性断裂问题,严重影响其安全服役。进行了锌基钎料的成分设计,分析了钎料的各项性能,得到优化的钎料成分。对铜板表面进行化学镀镍磷层改性,采用感应钎焊和优化的钎料进行了铜铝搭接钎焊试验。结果表明:在锌基钎料中提高Al含量,添加一定量Cu、Ag、稀土元素,可以提升钎料的润湿性能、强度和耐腐蚀性能。镍磷镀层显著提升了锌基钎料在铜板的润湿性能,改变了铜铝接头的界面反应,显著细化了焊缝晶粒。采用优化的锌基钎料和化学镀镍磷层工艺得到的铜铝接头的力学性能得到显著提升,剪切强度达37 MPa,疲劳寿命达85000次。

Cu/Al joints are widely applied in power electronic industry.However,brittle fracture occurs in the Cu/Al joints during long-term service,which seriously deteriorates the service safety.Zn-based solders were designed,and the properties were analyzed and optimal solder composition was obtained.The copper plate surface was modified by electroless Ni-P plating,and the Cu/Al lap brazing tests were carried out by using induction brazing and the optimal solder.The results show that increasing the Al content in the Zn-based brazing material and adding a certain amount of Cu,Ag and rare earth elements can enhance the wettability,strength and corrosion resistance of the brazing material.The nickel-phosphorus coating significantly improves the wetting performance of the Zn-based brazing material on the copper plate,changes the interface reaction of the copper-aluminum joints,and significantly refines the weld grain.The mechanical properties of the Cu/Al joint obtained using the optimized Zn-based brazing material and the electroless Ni-P plating process are significantly improved,the shear strength reaches 37 MPa and the fatigue life reaches 85000 times.