考虑晶粒结构的无铅焊点电迁移失效分析
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摘要
针对微观晶粒结构演化、尺度效应等微观晶粒结构诱致的电迁移失效问题,本文通过有限元分析软件,考虑焊点不同晶粒结构,对SAC305无铅焊点进行电迁移失效模式分析,进一步探明焊点电迁移失效机制。通过电子背散射衍射(EBSD)对焊点晶粒结构及其取向进行测定和表征,为有限元模型提供依据。采用Bunge欧拉角(φ_1,Φ,φ_2)来表示晶体的取向。结果表明单晶粒结构焊点正则化原子浓度及其焊点失效寿命在很大程度上取决于晶体取向(特别是Φ角,即晶体c轴取向与电流方向的夹角,该角度表征了β-Sn晶粒绕c轴的旋转)。模拟结果与电迁移实验结果较为吻合,进一步验证了该有限元分析方法的可行性。
In order to solve the problem of micro-grain structure evolution,scale effect and other electro-migration failures induced by microscopic grain structure,finite element analysis softw are was used to perform electromigration failure mode analysis on lead-free solder joints of SAC305,considering different grain structures of solder joints. The electromigration failure mechanism of solder joints was further confirmed. Electron backscattered diffraction( EBSD) was used to characterize the grain structure and track orientation in solder joints,which provided the basis for the finite element model. When Bunge Euler angles( φ_1,Φ,φ_2) are used to represent crystal orientation,the study result indicates that the normalized atomic density and the failure time of electromigration of single crystal bump are strongly impacted by crystal orientation especially the second Euler angle Φ,which is betw een the c axis orientation and the current direction and specifies the rotation of the c axis determines. The simulation results are in good agreement with the results of electromigration experiments,which further validates the feasibility of the finite element analysis method.
In order to solve the problem of micro-grain structure evolution,scale effect and other electro-migration failures induced by microscopic grain structure,finite element analysis softw are was used to perform electromigration failure mode analysis on lead-free solder joints of SAC305,considering different grain structures of solder joints. The electromigration failure mechanism of solder joints was further confirmed. Electron backscattered diffraction( EBSD) was used to characterize the grain structure and track orientation in solder joints,which provided the basis for the finite element model. When Bunge Euler angles( φ_1,Φ,φ_2) are used to represent crystal orientation,the study result indicates that the normalized atomic density and the failure time of electromigration of single crystal bump are strongly impacted by crystal orientation especially the second Euler angle Φ,which is betw een the c axis orientation and the current direction and specifies the rotation of the c axis determines. The simulation results are in good agreement with the results of electromigration experiments,which further validates the feasibility of the finite element analysis method.
引文
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[16]UBACHS R L M,SCHREURS P J G,GEER M G D.Elasto-viscoplastic nonlocal damage modelling of thermal fatigue in anisotropic lead-free solder[J].M ech M ater,2007,39(7):685-701.
[17]LOVBERG A,TEGEHALL P E,WETTER G,et al.Simulations of the impact of single-grained lead-free solder joints on the reliability of ball grid array components[C]//International Conference on Thermal,Mechanical and MultiPhysics Simulation and Experiments in Microelectronics and Microsystems.NY,USA:IEEE,2017:1-10.
[18]WANG Q,LIANG L,CHEN X,et al.Experimental determination and modification of Anand model constants for Pb-free material 95.5Sn4.0Ag0.5Cu[C]//International Conference on Thermal,M echanical and M ultiPhysics Simulation Experiments in M icroelectronics and M icro-Systems.NY,USA:IEEE,2007:1-9.
[19]NI J,LIU Y,HAO J,et al.Modeling microstructure effects on electromigration in lead-free solder joints[C]//Electronic Components and Technology Conference.NY,USA:IEEE,2014:1241-1246.
[20]张元祥.多物理场下金属微互连结构的电迁移失效及数值模拟研究[D].杭州:浙江工业大学,2011.
[21]HUANG M L,ZHAO J F,ZHANG Z J,et al.Dominant effect of high anisotropy inβ-Sn grain on electromigration-induced failure mechanism in Sn-3.0Ag-0.5Cu interconnect[J].J Alloy Compd,2016,678:370-374.
[22]BAI N,CHEN X,GAO H.Simulation of uniaxial tensile properties for lead-free solders w ith modified Anand model[J].M ater Des,2009,30(1):122-128.
[23]CERIC H,DE ORIO R L,ZISSER W,et al.M odeling of microstructural effects on electromigration failure[J].AIP Conf Prot,2014,1601:99.
[24]LU M,SHIH D Y,LAURO P,et al.Effect of Sn grain orientation on electromigration degradation mechanism in high Sn-based Pb-free solders[J].Appl Phys Lett,2008,92(21):1335.
[25]HUANG M L,ZHAO J F,ZHANG Z J,et al.Role of diffusion anisotropy inβ-Sn in microstructural evolution of Sn-3.0Ag-0.5Cu flip chip bumps undergoing electromigration[J].Acta M ater,2015,100:98-106.
[2]LIANG S W,CHEN C,HAN J K,et al.Blocking hillock and w hisker grow th by intermetallic compound formation in Sn-0.7Cu flip chip solder joints under electromigration[J].J Appl Phys,2010,107(9):1335.
[3]BIELER T R,JIANG H,LEHMAN L P,et al.Influence of Sn grain size and orientation on the thermomechanical response and reliability of Pb-free solder joints[J].IEEE Trans Compon Packg Technol,2015,31(2):370-381.
[4]SHEN Y A,CHEN C.Effect of Sn grain orientation on the formation of Cu6S5intermetallic compounds during electromigration[J].Scr M ater,2016,128:6-9.
[5]WANG Y,LU K H,GUPTA V,et al.Effects of Sn grain structure on the electromigration of Sn-Ag solder joints[J].J M ater Res,2012,27(8):1131-1141.
[6]ZHANG Q K,LONG W M,ZHANG Z F.Growth behavior of intermetallic compounds at Sn-Ag/Cu joint interfaces revealed by 3D imaging[J].J Alloy Compd,2015,646:405-411.
[7]SUN M L,ZHAO Z J,HU F T,et al.Effects of Sn layer orientation on the evolution of Cu/Sn interfaces[J].Electron M ater Lett,2018,14(4):526-532.
[8]ROSS G,TAO X,BROAS M,et al.Interfacial void segregation of Cl in Cu-Sn micro-connects[J].Electron M ater Lett,2017,13(4):1-6.
[9]YANG S,TIAN Y,WANG C.Investigation on Sn grain number and crystal orientation in the Sn-Ag-Cu/Cu solder joints of different sizes[J].J M ater Sci M ater Electron,2010,21(11):1174-1180.
[10]TASOOJI A,LARA L,LEE K.Effect of grain boundary misorientation on electromigration in lead-free solder joints[J].J Electron M ater,2014,43(12):4386-4394.
[11]ZHANG Y,LIANG L,CHEN X,et al.Impact of the UBM geometry and solder bump shape on electromigration reliability in a package system[C]//International Conference on Thermal,M echanical and M ulti-Physics Simulation and Experiments in M icroelectronics and M icrosystems.NY,USA:IEEE,2009:1-6.
[12]KINNEY C,LINARES X,LEE K O,et al.The effect of Sn orientation on intermetallic compound grow th in idealized Sn-Cu-Ag interconnects[J].J Electron M ater,2013,42(4):607-615.
[13]MERTENS J C E,KIRUBANDHAM A,CHAWLA N.Electromigration mechanisms in Sn-0.7Cu/Cu couples by four dimensional(4D)X-ray microtomography and electron backscatter diffraction(EBSD)[J].Acta M ater,2016,102:220-230.
[14]LEE K,KIM K S,TSUKADA Y,et al.Effects of the crystallographic orientation of Sn on the electromigration of Cu/Sn-Ag-Cu/Cu ball joints[J].J M ater Res,2011,114(3):467-474.
[15]梁利华,张元祥,刘勇,等.金属互连结构的电迁移失效分析新算法[J].固体力学学报,2010(2):164-172.
[16]UBACHS R L M,SCHREURS P J G,GEER M G D.Elasto-viscoplastic nonlocal damage modelling of thermal fatigue in anisotropic lead-free solder[J].M ech M ater,2007,39(7):685-701.
[17]LOVBERG A,TEGEHALL P E,WETTER G,et al.Simulations of the impact of single-grained lead-free solder joints on the reliability of ball grid array components[C]//International Conference on Thermal,Mechanical and MultiPhysics Simulation and Experiments in Microelectronics and Microsystems.NY,USA:IEEE,2017:1-10.
[18]WANG Q,LIANG L,CHEN X,et al.Experimental determination and modification of Anand model constants for Pb-free material 95.5Sn4.0Ag0.5Cu[C]//International Conference on Thermal,M echanical and M ultiPhysics Simulation Experiments in M icroelectronics and M icro-Systems.NY,USA:IEEE,2007:1-9.
[19]NI J,LIU Y,HAO J,et al.Modeling microstructure effects on electromigration in lead-free solder joints[C]//Electronic Components and Technology Conference.NY,USA:IEEE,2014:1241-1246.
[20]张元祥.多物理场下金属微互连结构的电迁移失效及数值模拟研究[D].杭州:浙江工业大学,2011.
[21]HUANG M L,ZHAO J F,ZHANG Z J,et al.Dominant effect of high anisotropy inβ-Sn grain on electromigration-induced failure mechanism in Sn-3.0Ag-0.5Cu interconnect[J].J Alloy Compd,2016,678:370-374.
[22]BAI N,CHEN X,GAO H.Simulation of uniaxial tensile properties for lead-free solders w ith modified Anand model[J].M ater Des,2009,30(1):122-128.
[23]CERIC H,DE ORIO R L,ZISSER W,et al.M odeling of microstructural effects on electromigration failure[J].AIP Conf Prot,2014,1601:99.
[24]LU M,SHIH D Y,LAURO P,et al.Effect of Sn grain orientation on electromigration degradation mechanism in high Sn-based Pb-free solders[J].Appl Phys Lett,2008,92(21):1335.
[25]HUANG M L,ZHAO J F,ZHANG Z J,et al.Role of diffusion anisotropy inβ-Sn in microstructural evolution of Sn-3.0Ag-0.5Cu flip chip bumps undergoing electromigration[J].Acta M ater,2015,100:98-106.