摘要
在微观尺度上,焊点的可靠性取决于焊料同焊盘之间界面反应生成的界面金属间化合物(IMC)的结构。通过金锗合金焊点的界面反应及微观结构随环境的变化表征了焊点的可靠性,研究了AuGe合金焊料与不同金层厚度的Ni/Au焊盘共晶焊接后其界面特征,同时总结了AuGe合金焊料在Cu和Ni等常见焊盘上的焊接润湿性及其焊接界面特征。切片分析结果显示,在共晶焊接后,厚金样品焊接界面冷却时焊料层析出富Au相形成不规则焊接结合层,Au层厚度减薄50%~60%;薄金样品的Au层全部消失,并在界面处形成很薄的一层富Ni的NiGe化合物。实验结果显示,厚Au层样品未出现Ni向焊接层扩散的现象和NiGe化合物的生成,厚Au层起到了阻挡层作用;薄金样品时,Ni通过互扩散缓慢与Ge形成NiGe化合物,在长期使用中焊接层会通过元素扩散等形式演变,使整个焊接层转变为含氧化层、富P层、NiGe层和AuCuGe合金层等多层结构的IMC,降低了焊点强度,严重影响焊接层可靠性。这说明IMC在焊接过程中主要以界面化学反应方式形成,服役过程中主要以元素扩散方式演变。
On a microscopic scale,the reliability of a solder joint depends on the structure of the interfacial intermetallic compound(IMC)formed by the interfacial reaction between the solder and the pad.The reliability of solder joints was characterized by the interfacial reaction of AuGe alloy solder joints and the change of microstructure with environment.After eutectic soldering,the interface characteristics of the AuGe alloy solders and Ni/Au pads with different gold thicknesses were studied.The solder wettability and soldering interface characteristics of the AuGe alloy solder on common pads such as Cu and Ni were summarized.The results of slicing analysis show that after the eutectic soldering,the solder layer precipitates out Au-rich phase to form an irregular solder joint layer when the soldering interface of the thick Au-samples are cooled,and the thickness of the Au layer is reduced by 50%-60%,all the Au layers of the thin gold sample disappear,and a very thin layer of Ni-rich NiGe compound is formed at the interface.The experimental results show that the diffusion of Ni to the solder layer and the formation of NiGe compound do not appear in the thick Au layer sample.The thick gold layer acts as a barrier layer.In the thin Au sample,NiGe compound is formed by Ge and Ni through slow interdiffusion.In long-term use,the solder layer can evolve through elemental diffusion and other forms,transforming the entire solder layer into an IMC containing a multilayer structure such as an oxide layer,a P-rich layer,a NiGe layer and an AuCuGe alloy layer,which reduces the solder joint strength and seriously affects the reliability of solder layer,indicating that the IMC is mainly formed by interfacial chemical reaction during the soldering process and mainly evolves in the form of elemental diffusion during the service.
作者
陈杰
刘峰
饶真真
杨春容
李晔
黄新临
Chen Jie;Liu Feng;Rao Zhenzhen;Yang Chunrong;Li Ye;Huang Xinlin(Chengdu Yaguang Electronic Ltd.Co.,Chengdu610051,China)
出处
《微纳电子技术》
北大核心
2020年第1期80-84,共5页
Micronanoelectronic Technology
作者简介
陈杰(1982—),男,陕西宝鸡人,硕士,高级工程师,主要从事微波器件/组件微组装技术及可靠性研究,E-mail:chen_jie88@163.com
