Size Effects of Growth and Evolution of Interfacial Intermetallic Compound and the Mechanical Behavior of Bump Structure Sn3.0Ag0.5Cu/Cu Cross-scale Joints in Electronic Packages

doi:10.3901/JME.2022.02.259

Abstract

Abstract: A mainstream lead-free Sn3.0Ag0.5Cu solder with cross-scale ball diameters in the range of 600 μm to 60 μm was used to attach on Cu pads to form micro-bump structure Sn3.0Ag0.5Cu/Cu(SAC305/Cu) joints by reflow at 260℃ for different dwelling times of 10 to 300 s. The microstructure evolution of interfacial intermetallic compound(IMC),shear strength and fracture behavior of SAC305/Cu cross-scale joints were investigated. Results show that for solder balls with diameter larger than 200 μm the growth rate of interfacial IMC layer of the joints increases with the decreasing solder joint size, while decreasing with the decrease of the solder joint size for solder balls with diameter less than 200 μm. Meanwhile, the coarsening growth of interfacial IMC grains exhibits two featured stages:Ostwald ripening growth and grain boundary absorption/migration growth, and the transition between two growth stages occurs earlier as the size of solder joints decreases. Under quasi-static shear loading, the shear strength of Sn3.0Ag0.5Cu/Cu joints increases with the decrease of the solder joint size. In the range of reflow time from 10 s to 300 s, the reflow time has little influence on shear strength of the joints, while showing an obvious effect on the fractural path of the joints.

Key words: microscale solder joint, intermetallic compound, grain growth, shear performance, size effect

CLC Number:

TG156

ZHOU Minbo, ZHAO Xingfei, CHEN Mingqiang, KE Changbo, ZHANG Xinping. Size Effects of Growth and Evolution of Interfacial Intermetallic Compound and the Mechanical Behavior of Bump Structure Sn3.0Ag0.5Cu/Cu Cross-scale Joints in Electronic Packages[J]. Journal of Mechanical Engineering, 2022, 58(2): 259-268.

References

[1] Hou S Y,Chen W C,Hu C,et al. Wafer-level integration of an advanced logic-memory system through the second-generation CoWoS technology[J]. IEEE Transactions on Electron Devices,2017,64(10):4071-4077.
[2] Lau J H. Heterogeneous integrations[M]. Singapore:Springer Nature Singapore Pte Ltd.,2019.
[3] Davis W R,Wilson J,Mick S,et al. Demystifying 3D ICs:The pros and cons of going vertical[J]. IEEE Design and Test of Computers,2005,22(6):498-510.
[4] Beica R,Sharbono C,Ritzdorf T. Through silicon via copper electrodeposition for 3D integration[C]//Proceedings of 58th Electronic Components and Technology Conference,Lake Buena Vista,Florida:IEEE 58th ECTC,2008:577-583.
[5] Yin Limeng,Zhang Xinping,Lu Chunsheng. Size and volume effects on the strength of microscale lead-free solder joints[J]. Journal of Electronic Materials,2009,38(10):2179-2183.
[6] Li Xunping,Xia Jianmin,ZhOU Minbo,et al. Solder volume effects on the microstructure evolution and shear fracture behavior of ball grid array structure Sn-3.0Ag-0.5Cu solder interconnects[J]. Journal of Electronic Materials,2011,40(12):2425-2435.
[7] Tu K N,Hsiao H Y,Chen C. Transition from flip chip solder joint to 3D IC microbump:Its effect on microstructure anisotropy[J]. Microelectronics Reliability,2013,53(1):2-6.
[8] Tian Yanhong,Hang Chunjin,Wang Chunqing,et al. Effects of bump size on deformation and fracture behavior of Sn3.0Ag0.5Cu/Cu solder joints during shear testing[J]. Materials Science and Engineering-A,2011,529:468-478.
[9] Annuar S,Mahmoodian R,Hamdia M,et al. Intermetallic compounds in 3D integrated circuits technology:A brief review[J]. Science and Technology of Advanced Materials,2017,18(1):693-703.
[10] Park Y S,Kwon Y M,Moon J T,et al. Effects of fine size lead-free solder ball on the interfacial reactions and joint reliability[C]//Proceedings of 60th Electronic Components and Technology Conference,Las Vegas,Nevada:IEEE 60th ECTC,2010,1436-1441.
[11] Huang M L,Yang F. Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate[J]. Scientific Reports,2014,4:7117.
[12] Ma Haoran,Kunwar A,Huang Ru,et al. Size effect on IMC growth induced by Cu concentration gradient and pinning of Ag₃Sn particles during multiple reflows[J]. Intermetallics,2017,90:90-96.
[13] Wang Bo,Wu Fengshun,Wu Yiping,et al. Effect of stand-off height on the microstructure and mechanical behavior of solder joints[J]. Soldering and Surface Mount Technology,2010,22(1):11-18.
[14] Liu Yingxia,Chu Y C,Tu K N. Scaling effect of interfacial reaction on intermetallic compound formation in Sn/Cu pillar down to 1μm diameter[J]. Acta Materialia,2016,117:146-152.
[15] Song Fubin,Lee S W R. Investigation of IMC thickness effect on the lead-free solder ball attachment strength:Comparison between ball shear test and cold bump pull test results[C]//Proceedings of 56th Electronic Components and Technology Conference,San Diego,California:IEEE 56th ECTC,2006,1196-1203.
[16] Kotadia H R,Howes P D,Mannan S H. A review:On the development of low melting temperature Pb-free solders[J]. Microelectronics Reliability,2014,54(6-7):1253-1273.
[17] Kim H K,Tu K N. Kinetic analysis of the soldering reaction between eutectic SnPb alloy and Cu accompanied by ripening[J]. Physical Review B,1996,53(23):16027-16034.
[18] Zhang Zhihao,Li Mingyu,Wang Chunqing. Fabrication of Cu₆Sn₅ single-crystal layer for under-bump metallization in flip-chip packaging[J]. Intermetallics,2013,42:52-55.
[19] Ourdjini A,Hanim M A A,Koh S F J,et al. Effect of solder volume on interfacial reactions between eutectic Sn-Pb and Sn-Ag-Cu solders and Ni(P)-Au surface finish[C]//Proceedings of 31th International Electronics Manufacturing Technology Symposium,Petaling Jaya,Malaysia:CPMT International Electronics Manufacturing Technology Symposium,2006,437-442.
[20] Chang C C,Lin Y W,WANG Y W,et al. The effects of solder volume and Cu concentration on the consumption rate of Cu pad during reflow soldering[J]. Journal of Alloys and Compounds,2010,492(1):99-104.
[21] Huang J Q,Zhou M B,LIANG S B,et al. Size effects on the interfacial reaction and microstructural evolution of Sn-ball/Sn3.0Ag0.5Cu-paste/Cu joints in board-level hybrid BGA interconnection at critical reflowing temperature[J]. Journal of Materials Science:Materials in Electronics,2018,29(9):7651-7660.
[22] Gusak A M,Tu K N. Kinetic theory of flux-driven ripening[J]. Physical Review B,2002,66(11):115403.
[23] Zhou M B,Zhao X F,YUE W,et al. Unique interfacial reaction and so-induced change in mechanical performance of Sn-3.0Ag-0.5Cu/Cu solder joints formed during undercooled and eutectic liquid soldering processes[J]. Journal of Materials Science:Materials in Electronics,2019,30(5):4770-4781.