Study Of Cu-Ti-based Active Filler Alloy Brazing Al₂O₃Ceramics To Cu

Abstract:Al2O3ceramics is the most production and the most widely used ceramics in the world, the connectors of Al2O3ceramics with copper are widely used in vacuum electron devices, thus it is important to effectively bond Al2O3ceramics and copper. In this paper, we study the different components of Cu-Ti-based active filler successfully replace Ag-based active brazing to bond Al2O3ceramics with copper. The reaction layer thickness of Al2O3/Cu used different active filler were measured by microscope. The interfacial microstructure and composition distribution of Al2O3/Cu reaction layer used different active fillers brazing was observed by SEM、EDS. The effect of different component active filler; Ti wt%and brazing process on the wettability and bonding strength was investigated. The bonding strength of joints was studied when trace elements added to active fillers. Through the wettability on Al2O3ceramics and the welding performance of Al2O3/Cu, conclusions are as flollows:(1) Study of wettability of Cu-Ti active filler on Al2O3ceramics, the results show the Ti content of filler is the key factors affecting to wetting Al2O3ceramics, when the Ti content is below20%, the filler cannot wet Al2O3ceramics. As the Ti content increased, the contact angle of filler with Al2O3ceramics surface decrease. With the extension of holding time, the spreadability is slowly increase, the reaction layer thickness increases and the organization become dense.(2) Study of wettability of Cu67SnlOTi23active filler on Al2O3ceramics, the precursor film phenomenon occurring on the Al2O3ceramics surface, which shows its excellent wettability. Using Cu67SnlOTi23active filler brazing Al2O3ceramics to copper, the bonding strength of joint is increase as increasing the holding time and brazing temperature, however the bonding strength is low. The reaction layer was analyzed to find the Sn element of the filler occurs segregation and replace the Cu atom, generates a large amount of Sn-Ti compounds.(3) Adding trace element Ni in Cu67SnlOTi23active filler, it can effectively improve the strength of joint at the brazing temperature of 900℃. When the Ni content is4%, the strength of joint arrive maximum95.42MPa. Some phase which contain Ni element generated in the reaction layer. These phases generated with the Ni content increasing. It shows these phases are conductive to improve the strength of joint.(4) Adding trace element B in the Cu63Sn10Ti23Ni4active filler, the result show that when B content below0.2%, the filler doesn’t spatter in the process of brazing Al2O3/Cu, with the B content of filler increasing to0.3%, splashing phenomenon is very obvious. Adding trace element Al in the Cu62.8Sn10Ti23Ni4B0.2active filler. When the Al content is0.2%, the strength of joint arrive132.43MPa, however when the Al content increase to0.5%, the joint of Al2O3/Cu is all solder skips.