针对靶材背板扩散焊Co/Al/Cu三明治结构，采用有限元法研究了Al中间层和Ni(V)过渡层对其焊接残余应力的影响。结果表明，Al中间层的存在，不仅能使扩散焊过程更容易进行，降低扩散焊温度，同时也能缓解焊接残余应力，使靶材背板扩散焊组件最大残余应力从142 MPa降低到126 MPa，最大残余应力的位置也从靶材外边缘和背板的界面处变为靠近靶材中心和Co/Al界面处，并且存在厚度为7 mm的最优中间层。Ni(V)过渡层的存在虽然能够抑制Co/Al和Cu/Al界面处脆性金属间化合物的生成，但同时也使焊接残余应力增大，并且只在Co/Al界面处添加Ni(V)过渡层时残余应力的增大程度小于在Co/Al和Cu/Al界面处都添加Ni(V)过渡层时的残余应力的增大程度。

Sputtering has been widely used to prepare thin film due to its good cohesion with substrate, high purity, compactness, repeatability and large area manufacture. Target is a key consumable material during production of thin film by sputtering. Generally, targets are mostly rare and high purity metal, so the cost of target is very high. In order to reduce the cost of target, to improve its stiffness, and to enhance the electrical and thermal conductivity, target is usually connected with backplane to form the target assembly. The main connection method is diffusion welding, which is used in the industrial production. However, the target and the backplane are usually two different materials with different physical properties such as coefficient of thermal expansion (CTE) and thermal conductivity. During the welding or soldering process of target, the mismatch of physical properties will lead to residual stress in target, which has a direct influence on the thickness and microstructure uniformity of the films. Hence, it is very meaningful to investigate the residual stress in target and to study its influencing factor. Based on the Co/Al/Cu sandwich structure of backplane diffusion welding, the effects of Al interlayer and Ni(V) layer on welding residual stress were studied by finite element method. It was found that the application of the Al interlayer not only can make diffusion welding process easier and lower the diffusion welding temperature, but also can reduce the maximum residual stress from 142 MPa to 126 MPa. Furthermore, the location of the maximum residual stress also changes from the outer edge of the interface between target and backplane to the position near the symmetrical axis of target and Co/Al interface. Furthermore, there is an optimal thickness for Al interlayer (7 mm). Although the existence of Ni(V) layer can inhibit the generation of brittle intermetallic compounds at the interface of Co/Al and Cu/Al, it also increases the residual stress. Moreover, we find that the increase of residual stress with Ni(V) layer at only Co/Al interface, is smaller than that of adding Ni(V) layer at both Co/Al and Cu/Al interfaces.