Sn-1.5Ag-2Zn低银无铅焊料与取向铜界面研究  

Interface between Sn-1.5Ag-2Zn Low Silver Lead-free Solder and Oriented Copper

作　　者：肖金 屈福康 程伟 李武初 XIAO Jin;QU Fu-kang;CHENG Wei;LI Wu-chu(Guangzhou Huali College,Guangzhou 511300,China)

机构地区：[1]广州华立学院,广州511300

出　　处：《表面技术》2023年第8期406-412,共7页Surface Technology

基　　金：广州市科技计划基础与应用基础研究项目(202102080571);2021年度增城区科技创新资金计划(2021ZCMS11)。

摘　　要：目的高密度封装技术能减少焊盘尺寸和焊盘里面所含晶粒的数量,当多晶焊盘转为单晶焊盘时,晶粒的取向会对界面处金属间化合物的形成产生重要影响。选取具有发展前景的Sn-1.5Ag-2Zn作为焊料合金,研究焊料与单晶(111)铜基板界面反应,得到金属间化合物的生长动力学规律。方法将Sn-1.5Ag-2Zn无铅焊料分别与单晶(111)铜基板及多晶紫铜基板在250℃下进行回流焊接5 min,将焊接后的样品在160℃下分别进行20 h,100 h,300 h,600 h热处理。用扫描电子显微镜背散射电子成像和二次电子成像、X射线衍射仪(XRD)、能谱仪等研究焊接界面处的显微组织、金属间化合物成分以及性能。结果合金焊料与铜基板接触迅速生长出凹凸不平类似扇贝状Cu_(6)Sn_(5)金属间化合物层,与单晶铜表面形成的Cu_(6)Sn_(5)晶粒尺寸比多晶铜的大,单晶铜无晶界阻挡原子扩散,影响晶粒形核与长大。合金焊料与单晶(111)铜焊点在160℃下热处理20 h快速形成的Cu_(6)Sn_(5)生长速度是多晶铜上焊点的2倍左右。而后随热处理时间增加增长缓慢,热处理600 h后厚层Cu_(6)Sn_(5)由于裂纹扩散出现溃断,金属间化合物的厚度维持在3.5μm。焊料与多晶铜焊点在热处理过程中生成的Cu_(5)Zn_(8)起到阻挡层的作用,阻挡焊料与铜基板接触,抑制Cu_(6)Sn_(5)生成,热处理300 h后Cu_(5)Zn_(8)破碎分解,Cu_(6)Sn_(5)在阻挡层消失后快速生长,厚度约为2.8μm。结论单晶铜上焊点金属间化合物的厚度比多晶铜上金属间化合物的厚度多0.7μm,热处理后合金焊料与单晶铜界面形成的金属间化合物致密性更好,基本没有孔隙,而合金焊料与多晶铜界面上金属间化合物晶粒间存在明显孔隙,可以预测合金焊料与单晶铜界面的焊接质量更好。High density packaging technology reduces the pad size and the number of grains contained in the pad.When the polycrystalline pad turns into a single crystal pad,the grain orientation has an important impact on the formation of the intermetallic compounds at the interface.Sn-1.5Ag-2Zn,a promising solder alloy,was selected to study the interfacial reaction between solder and single crystal(111)copper substrate,and the growth kinetics of intermetallic was obtained.Sn-1.5Ag-2Zn lead-free solder was refluxed with single crystal(111)copper substrate and polycrystalline red copper substrate at 250℃for 5 min,and the welded sample was heat-treated at 160℃for 20 h,100 h,300 h and 600 h respectively.The microstructure,composition and properties of intermetallic at the welding interface were studied by Scanning Electron Microscope,Backscattered Electron Imaging,Secondary Electron Imaging,X-ray Diffraction(XRD)and Energy Dispersive Spectrometer.The uneven scallop like Cu_(6)Sn_(5)intermetallic compound layer grew rapidly when the alloy solder contacted with the copper substrate.The Cu_(6)Sn_(5)grain size formed on the surface of single crystal copper was larger than that of polycrystalline copper.Single crystal copper had no grain boundary to block atomic diffusion,which affected grain nucleation and growth.The growth rate of Cu_(6)Sn_(5)formed by alloy solder and the single crystal(111)copper solder joint after heat treatment at 160℃for 20 h was about twice that of the polycrystalline copper solder joint.Then,it grew slowly with the increase of heat treatment time.After 600 h of heat treatment,the thick layer of Cu_(6)Sn_(5)broke due to crack diffusion,and the thickness of intermetallic compound remained at 3.5μm.Cu_(5)Zn_(8)generated at the solder and polycrystalline copper solder joint during heat treatment acted as a barrier layer,preventing the solder from contacting the copper substrate and inhibiting the formation of Cu_(6)Sn_(5).After 300 h of heat treatment,Cu_(5)Zn_(8)was broken and decomposed,and Cu_(6)Sn_(

关 键 词：Sn-1.5Ag-2Zn 单晶铜 合金焊料 焊接 扩散 

分 类 号：TB31[一般工业技术—材料科学与工程]