Study Of Active Bonding Mechanism Between Bi42Sn2Ag2Ti(Ce,Ga) And Quartz Glass Substrate At Low Temperature

Quartz glass possessing outstanding mechanical,optical and electrical properties,has been widely used in the industry of semiconductor and becomes a potential candidate material for microelectronic packaging.However,the quartz glass is difficult to be wetted by conventional solders,so it needs to be metalized to the surface of glass.Active solder is suitable for direct welding of hard wettable ceramic materials,but brazing requires high temperature conditions,which has the problem of large residual stress in joints,and is not suitable for temperature sensitive device packaging.Therefore,it is of great significance and application prospect to study the low temperature active welding of quartz glass.In this work,quartz glass is soldered by low-temperature active solder.The mechanism of low-temperature active soldering is investigated in order to provide experimental and theoretical basis for the high-reliability and low-cost joining of quartz glass and the optimization of active soldering process parameters.The main research contents are as follows:The microstructure,the element distribution and the interface reaction products between quartz glass/Bi42Sn2Ag2Ti（Ce,Ga）/quartz glass have been investigated by using scanning electron microscopy,energy-dispersive spectroscopy and transmission electron microscope in this work.The experiment results show that quartz glass can be bonded well by active solder Bi42Sn2Ag2Ti（Ce,Ga）at both 170℃and 290℃in air.Ti segregates at the solid-liquid interface during the soldering process and Ti O and Ti O₂ are formed at the interface.The mechanical properties of joints have been evaluated through the shear testing.The results show that the shear strength increases with the increase of the welding temperature,and has the trend of first increase and then decrease with the increase of the holding time.The joint soldered for15 min possess the maximum shear strength of 24.50 MPa.The fracture of the joint might be brittle-plastic mixed mechanism.The mechanism of low temperature active soldering of quartz glass/Bi42Sn2Ag2Ti（Ce,Ga）/quartz glass has been analyzed based on bond parameter theory,reaction thermodynamics theory,active adsorption process and reaction mechanism.The results show that the interaction between Ti and O is the strongest,and it is easier to form chemical bonds;Ti adsorption energy on the Si O₂ surface is-16.61 k J/mol,so that Ti will be enriched on the surface of quartz glass.The segregation of Ti at the solid-liquid interface provides the Ti concentration required for the interface reaction.The reaction occurs and the Ti element is precipitated at the interface in the form of Ti O₂ and Ti O.The wettability of quartz glass is promoted by both of active adsorption and interfacial reaction products.The low-temperature active soldering process of quartz glass can be divided into three stages:（a）Ti atoms uniformly diffuse into the solder through Brownian motion;（b）driven by the concentration gradient and active adsorption,Ti element from the inside of the solder segregates at solid-liquid interface;（c）interfacial reaction occurs to generate TiO and TiO₂,where TiO₂ is originate from further reaction of TiO.