Theoretical Calculation Of Surface Tension Of Silver Alloy At High Temperature

With the great improvement of the integration of semiconductor devices and the rapid growth of the number of electrodes on electronic boards,chips and LEDs,higher requirements are put forward for bonding wires used in electronic device packaging in the electronic device manufacturing industry.Therefore,it is urgent to develop new bonding wires.Silver bonding wire is not only similar to gold bonding wire in performance,but also much lower in cost than gold bonding wire.Therefore,silver bonding wire is gradually replacing gold wire as a new bonding packaging material.The traditional research and development method of new bonding wire materials is to explore the influence of different alloying elements on the properties of bonding wire through a large number of experiments and tests,and to find the optimum alloy composition ratio.But using this method not only has a long experiment period,but also costs a lot.Therefore,it is necessary to use theoretical methods to calculate and predict the properties of the bonding wires,so as to reveal the effect of alloying elements on the properties of the bonding wires,and to guide the experimental work.For bonding wire,the bonding performance is a key factor in the design of bonding wire composition.It is related to the surface tension of the bonding wire corresponding to the alloy melted at high temperature.In this paper,the surface tension of silver alloy in high temperature liquid state is calculated theoretically by thermodynamic model and molecular dynamics method when different alloy elements are added at the ratio of 10 to 100 at%.This provides theoretical basis for the composition design of silver bonding wire,and is of great significance for reducing the research and development cycle of silver bonding wire and saving the research cost.Firstly,the surface tension of Ag-X binary liquid alloy with Au,Bi,Ce,Cu,In,Sb,Sn,Pd,Ni and Y as alloying elements was calculated by Butler model,and the effect of adding alloy element X on the surface tension of Ag alloy was investigated.The results show that the surface tensions of Ag at 1381 K and 1873 K are 0.89392 N/m and 0.7906 N/m,respectively.When the elements of Cu,Au,Sn and Bi are added to Ag,the theoretical calculated surface tension is not much different from the experimental value,and the error is less than 10%.This shows that the Butler model is reliable and reasonable for calculating the surface tension of binary alloys.When In,Sn,Sb and Bi are added to Ag,the surface tension of the alloy will be reduced,and the order of decreasing percentage is In < Sn < Sb < Bi.When Au,Cu,Pd,Ni and Y are added to Ag,the surface tension of the alloy will increase.For the alloying element Ce,the surface tension of Ag alloy increases with the addition of a small amount of Ce,but decreases with the addition of more Ce.When the content of alloying elements is 10 at%,the surface tension curve of binary alloys shows a linear change trend with temperature.The surface tension of Ag-10at%X(Au,Ce,Cu,In,Sb,Sn,Pd,Ni,Y)alloy decreases with the increase of temperature,while the surface tension of Ag-10at%Bi binary alloy increases with the increase of temperature.Secondly,the trend of surface tension of Ag-Au,Ag-Pd and Au-Pd alloys varying with composition or temperature was calculated by molecular dynamics simulation.The results show that the elastic constants and modulus of three pure metals Ag,Au and Pd and their corresponding alloys calculated by molecular dynamics at 0 K differ little from the experimental values.The surface tension calculated by molecular dynamics differs little from the experimental values,and the variation trend of surface tension with composition of binary alloys is consistent with the experimental results.The surface tension of Ag-Au binary alloys ranged from 0.89633 N/m to 1.16087 N/m at 1381 K,with the increase of Au atom content.The surface tension of Ag-Pd binary alloys ranged from 0.76231 N/m to 1.48508 N/m at 1900 K,with the increase of Pd atom content.The surface tension of Au-Pd binary alloys ranged from 1.0326 N/m to 1.48508 N/m at 1900 K,with the increase of Pd atom content.In addition,when 40 at% alloying element is added,the curve of surface tension with temperature is calculated by molecular dynamics to be non-linear.Among them,the non-linear trend of surface tension of Ag-40at%Au binary alloy is the most obvious.Finally,on the basis of calculating the surface tension of binary alloys,the surface tension of ternary alloys containing Ag element is calculated by Toop model.The results show that the surface tension of Ag-Cu-Sn ternary alloy calculated by Toop model with a specific composition at 1381 K differs little from the experimental results,and the error is less than 6.44%.The variation of surface tension of Ag-Au-Cu ternary alloy with Au or Cu content ranges from 0.89392 N/m to 1.32471 N/m at 1381 K.The variation of surface tension of Ag-Au-Ce ternary alloy with Au or Ce content ranges from 0.66219 N/m to 1.078 N/m at 1673 K.The variation of surface tension of Ag-Au-Pd ternary alloy with Au or Pd content ranges from 0.7906 N/m to 1.468608 N/m at 1873 K.