微小互连高度对倒装芯片组装焊点显微组织及力学性能的影响
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摘要
研究了不同互连高度的Cu/SAC305/Cu焊点的显微组织变化及力学性能。结果表明,随互连高度降低,焊点两侧IMC层的厚度降低,而相应的IMC占焊点的比例却逐渐增高;此外,当互连高度降低,焊料层应变速率及焊点结构系数d/δ均增大,两者共同提高了微焊点的抗拉强度。当焊点互连高度为100,50,20μm时,焊点断口特征均为韧性断裂,而当焊点互连高度为10μm时,其断口特征为脆性断裂。
The microstructural variation and mechanical properties of Cu/SAC305/Cu solder joints with different stand-off height(SOH) were studied.The results show that with the reducing SOH the thickness of intermetallic(IMC) layer at both sides of solder joints decreases with increased IMC to solder joint ratio.In addition,as the SOH decreases,both the strain rate of solder layer and structural coefficient d/δ of solder joint increase,which jointly improves the tensile strength of micro solder joint.The fracture characteristic of micron solder joints with SOH of 100 μm,50 μm and 20 μm is ductile fracture,while it is brittle fracture when the SOH of solder joint is 10 μm.
The microstructural variation and mechanical properties of Cu/SAC305/Cu solder joints with different stand-off height(SOH) were studied.The results show that with the reducing SOH the thickness of intermetallic(IMC) layer at both sides of solder joints decreases with increased IMC to solder joint ratio.In addition,as the SOH decreases,both the strain rate of solder layer and structural coefficient d/δ of solder joint increase,which jointly improves the tensile strength of micro solder joint.The fracture characteristic of micron solder joints with SOH of 100 μm,50 μm and 20 μm is ductile fracture,while it is brittle fracture when the SOH of solder joint is 10 μm.
引文
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[2]许利伟.倒装芯片微凸点焊工艺研究及焊点应变有限元仿真 [D].大连:大连理工大学,2016.
[3]Sridharan V,Goyal A,Sitaraman S,et al.Ultra-miniaturized WLAN RF receiver with chip-last GaAs embedded active [C]//2011 IEEE 61st Electronic Components and Technology Conference (ECTC).NY,USA:IEEE,2011:1371-1376.
[4]Kao T Y J,Yan Y,Shen T M,et al.Design and analysis of a 60-GHz CMOS Doppler micro-radar system-in-package for vital-sign and vibration detection [J].IEEE Transactions on Microwave Theory and Techniques,2013,61(4):1649-1659.
[5]尹立孟,李望云,位松,等.焊点尺寸对微焊点拉伸断裂强度的影响[J].电子元件与材料,2011,30(9):57-60.
[6]王刚,尹立孟,姚宗湘,等.热时效及电迁移对不同体积SnAgCu微焊点强度影响研究 [J].焊接技术,2016(10):24-27.
[7]张春红,江馨,岳精雷,等.温度梯度对Cu/Sn/Cu微焊点界面反应和剪切强度的影响 [J].重庆理工大学学报(自然科学),2018,32(4):119-126.
[8]Gong J,Liu C C,Conway P P,et al.Evolution of CuSn intermetallics between molten SnAgCu solder and Cu substrate [J].Acta Materialia,2008,56(16):4291-4297.
[9]李超,胡小武,李玉龙,等.液态Sn3.0Ag0.5Cu钎料与Cu、Fe及Co基板界面反应研究 [J].功能材料,2018,49(2):2163-2168.
[10]Yang M,Li M,Wang L,et al.Growth behavior of Cu6Sn5 grains formed at an Sn3.5Ag/Cu interface [J].Materials Letters,2011,65(10):1506-1509.
[11]Zimprich P,Betzwar-Kotas A,Khatibi G,et al.Size effects in small scaled lead-free solder joints [J].Journal of Materials Science:Materials in Electronics,2008,19(4):383-388.