本研究添加銅元素(0.1、0.2、0.4 wt%)與鈦元素(0.01、0.02、0.04 wt%)於Zn-25Sn合金中，分析研究此系列合金與鎳基板接合後，其銲錫接點微結構、剪力性質及界面反應的行為。Ni/Zn-25Sn/Ni接點微結構由界面γ-Ni5Zn21介金屬化合物與富鋅相(α-Zn)和錫鋅共晶相構成的銲錫基地相所組成。添加的銅元素於基地相中形成銅鋅固溶體，也會聚集在界面介金屬化合物層中，而添加的鈦元素能使富鋅相組織細化。界面介金屬化合物主要由凝核區、柱狀晶區域和等軸晶區域三種型態的晶粒所組成。添加的銅和鈦元素對於銲錫接點迴焊試片剪力強度沒有明顯的影響，最大剪力強度大約在29-33MPa的範圍內；接點進行250℃時效處理後，最大剪力強度隨時效時間增長而下降，在時效36小時後下降到22.4-24.8MPa的範圍中。銲錫接點的破斷位置主要在界面介金屬化合物與鎳基板的界面處，而時效試片的剪力破裂行為中，裂縫的行進會由界面處進入介金屬化合物層中。在界面反應中，介金屬化合物的成長機制屬於反應控制，添加銅和鈦元素皆會使成長活化能上升，鈦元素對活化能的影響在添加0.02wt%時達最大值，為26.86 kJ/mole。

This study investigated the effect of Cu (0.1, 0.2, 0.4 wt%) and Ti (0.01, 0.02, 0.04 wt%) additions on the shear properties, interfacial reaction and microstructure of high temperature Ni/Zn-25Sn-xCu-yTi/Ni solder joints. Ni/Zn-25Sn/Ni consisted of interfacial Ni5Zn21 intermetallic and the solder matrix composed of Zn rich phase and the Sn-Zn eutectic phase. The Cu addition dissolved into Zn rich phase to form Cu-Zn solid solution and aggregated in the intermetallic layer. The Ti addition resulted in Zn rich phase refinement. The microstructure of intermetallic consisted of three different types of grains, including nucleation zone, columnar zone and equiaxed zone. The Cu and Ti addition didn’t have significant effect on the shear strength of the solder joints, and the USS ranged from 29 to 34MPa. After aging treatment, the shear strength of solder joints decreased with the aging time, and the USS decreased to 22.4-24.8MPa after solder joints aged at 250℃ for 36 hours. The fracture of solder joints mainly occurred at the interface between intermetallic layer and Ni substrate. However, for aged solder joints, crack propagated from the intermetallic/Ni substrate interface into intermetallic layer during shear test, causing the decrease of USS. In the Zn-25Sn-xCu-yTi/Ni interfacial reaction, the growth mechanism of Ni5Zn21 intermetallic was reaction controlled, and Cu and Ti addition made activation energy of intermetallic growth increase, but the effect of Ti addition on the activation energy reached a maximum value of 26.86 kJ/mole when Ti content was 0.02wt%.

[1] M. Abtew and G. Selvaduray, "Lead-free solders in microelectronics," Materials Science and Engineering: R: Reports, vol. 27, no. 5-6, pp. 95-141, 2000.
[2] J. H. Pang, K. H. Tan, X. Shi, and Z. Wang, "Thermal cycling aging effects on microstructural and mechanical properties of a single PBGA solder joint specimen," IEEE Transactions on Components and Packaging Technologies, vol. 24, no. 1, pp. 10-15, 2001.
[3] N. Chawla, "Thermomechanical behaviour of environmentally benign Pb-free solders," International Materials Reviews, vol. 54, no. 6, pp. 368-384, Nov 2009.
[4] X. Hu, T. Xu, L. M. Keer, Y. Li, and X. Jiang, "Microstructure evolution and shear fracture behavior of aged Sn3Ag0. 5Cu/Cu solder joints," Materials Science and Engineering: A, vol. 673, pp. 167-177, 2016.
[5] F. W. Gayle et al., "High temperature lead-free solder for microelectronics," Jom, vol. 53, no. 6, pp. 17-21, 2001.
[6] S. Menon, E. George, M. Osterman, and M. Pecht, "High lead solder (over 85%) solder in the electronics industry: RoHS exemptions and alternatives," Journal of Materials Science: Materials in Electronics, vol. 26, no. 6, pp. 4021-4030, 2015.
[7] V. Chidambaram, J. Hattel, and J. Hald, "High-temperature lead-free solder alternatives," Microelectronic Engineering, vol. 88, no. 6, pp. 981-989, 2011.
[8] Y. Yamada et al., "Pb-free high temperature solders for power device packaging," Microelectronics Reliability, vol. 46, no. 9-11, pp. 1932-1937, 2006.
[9] K. Suganuma, S.-J. Kim, and K.-S. Kim, "High-temperature lead-free solders: Properties and possibilities," JOM Journal of the Minerals, Metals and Materials Society, vol. 61, no. 1, pp. 64-71, 2009.
[10] V. Chidambaram, J. Hattel, and J. Hald, "Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system," Materials & Design, vol. 31, no. 10, pp. 4638-4645, 2010.
[11] K.-N. Tu, A. M. Gusak, and M. Li, "Physics and materials challenges for lead-free solders," Journal of applied Physics, vol. 93, no. 3, pp. 1335-1353, 2003.
[12] G. Zeng, S. McDonald, and K. Nogita, "Development of high-temperature solders," Microelectronics Reliability, vol. 52, no. 7, pp. 1306-1322, 2012.
[13] J.-M. Song, M.-J. Lin, K.-H. Hsieh, T.-Y. Pai, Y.-S. Lai, and Y.-T. Chiu, "Ball impact reliability of Zn-Sn high-temperature solder joints bonded with different substrates," Journal of electronic materials, vol. 42, no. 9, pp. 2813-2821, 2013.
[14] R. Venkatraman, J. R. Wilcox, and S. R. Cain, "Experimental study of the kinetics of transient liquid phase solidification reaction in electroplated gold-tin layers on copper," Metallurgical and Materials Transactions A, vol. 28, no. 3, pp. 699-706, 1997.
[15] D. Ivey, "Microstructural characterization of Au/Sn solder for packaging in optoelectronic applications," Micron, vol. 29, no. 4, pp. 281-287, 1998.
[16] H. Song, J. Ahn, and J. Morris, "The microstructure of eutectic Au-Sn solder bumps on Cu/electroless Ni/Au," Journal of electronic materials, vol. 30, no. 9, pp. 1083-1087, 2001.
[17] H. G. Song, J. Morris, and M. McCormack, "The microstructure of ultrafine eutectic Au-Sn solder joints on Cu," Journal of electronic materials, vol. 29, no. 8, pp. 1038-1046, 2000.
[18] W. Liu, Y. Wang, Y. Ma, Q. Yu, and Y. Huang, "Interfacial microstructure evolution and shear behavior of Au–20Sn/(Sn) Cu solder joints bonded at 250° C," Materials Science and Engineering: A, vol. 651, pp. 626-635, 2016.
[19] X.-f. Wei, Y.-k. Zhang, R.-c. Wang, and Y. Feng, "Microstructural evolution and shear strength of AuSn20/Ni single lap solder joints," Microelectronics Reliability, vol. 53, no. 5, pp. 748-754, 2013.
[20] J.-W. Yoon et al., "Mechanical reliability of Sn-rich Au–Sn/Ni flip chip solder joints fabricated by sequential electroplating method," Microelectronics reliability, vol. 48, no. 11-12, pp. 1857-1863, 2008.
[21] I. Karakaya and W. Thompson, "The Ag-Bi (silver-bismuth) system," Journal of phase equilibria, vol. 14, no. 4, pp. 525-530, 1993.
[22] J.-M. Song, H.-Y. Chuang, and Z.-M. Wu, "Interfacial reactions between Bi-Ag high-temperature solders and metallic substrates," Journal of Electronic Materials, vol. 35, no. 5, pp. 1041-1049, 2006.
[23] J.-M. Song, H.-Y. Chuang, and Z.-M. Wu, "Substrate dissolution and shear properties of the joints between Bi-Ag alloys and Cu substrates for high-temperature soldering applications," Journal of Electronic Materials, vol. 36, no. 11, pp. 1516-1523, 2007.
[24] J. Murray, "The Al− Zn (aluminum-zinc) system," Bulletin of Alloy Phase Diagrams, vol. 4, no. 1, pp. 55-73, 1983.
[25] N. Kang, H. S. Na, S. J. Kim, and C. Y. Kang, "Alloy design of Zn–Al–Cu solder for ultra high temperatures," Journal of Alloys and compounds, vol. 467, no. 1-2, pp. 246-250, 2009.
[26] S.-J. Kim, K.-S. Kim, S.-S. Kim, C.-Y. Kang, and K. Suganuma, "Characteristics of Zn-Al-Cu alloys for high temperature solder application," Materials transactions, vol. 49, no. 7, pp. 1531-1536, 2008.
[27] M. A. El-Khair, A. Daoud, and A. Ismail, "Effect of different Al contents on the microstructure, tensile and wear properties of Zn-based alloy," Materials Letters, vol. 58, no. 11, pp. 1754-1760, 2004.
[28] Y. Takaku, L. Felicia, I. Ohnuma, R. Kainuma, and K. Ishida, "Interfacial reaction between Cu substrates and Zn-Al base high-temperature Pb-free solders," Journal of Electronic Materials, vol. 37, no. 3, pp. 314-323, 2008.
[29] Y. Xiao, M. Li, L. Wang, S. Huang, X. Du, and Z. Liu, "Interfacial reaction behavior and mechanical properties of ultrasonically brazed Cu/Zn–Al/Cu joints," Materials & Design, vol. 73, pp. 42-49, 2015.
[30] Y. Takaku et al., "Interfacial reaction between Zn-Al-based high-temperature solders and Ni substrate," Journal of Electronic Materials, vol. 38, no. 1, pp. 54-60, 2009.
[31] H. Baker and H. Okamoto, "ASM Handbook. Vol. 3. Alloy Phase Diagrams," ASM International, Materials Park, Ohio 44073-0002, USA, 1992. 501, 1992.
[32] S.-W. Chen, C.-H. Wang, S.-K. Lin, and C.-N. Chiu, "Phase diagrams of Pb-free solders and their related materials systems," in Lead-Free Electronic Solders: Springer, 2006, pp. 19-37.
[33] J.-E. Lee, K.-S. Kim, K. Suganuma, J. Takenaka, and K. Hagio, "Interfacial properties of Zn–Sn alloys as high temperature lead-free solder on Cu substrate," Materials Transactions, vol. 46, no. 11, pp. 2413-2418, 2005.
[34] S. Kim, K.-S. Kim, S.-S. Kim, and K. Suganuma, "Interfacial reaction and die attach properties of Zn-Sn high-temperature solders," Journal of Electronic Materials, vol. 38, no. 2, pp. 266-272, 2009.
[35] J.-E. Lee, K.-S. Kim, K. Suganuma, M. Inoue, and G. Izuta, "Thermal properties and phase stability of Zn-Sn and Zn-In alloys as high temperature lead-free solder," Materials transactions, vol. 48, no. 3, pp. 584-593, 2007.
[36] R. Mahmudi and M. Eslami, "Shear strength of the Zn–Sn high-temperature lead-free solders," Journal of Materials Science: Materials in Electronics, vol. 22, no. 8, pp. 1168-1172, 2011.
[37] R. Mahmudi and M. Eslami, "Impression creep behavior of Zn-Sn high-temperature lead-free solders," Journal of electronic materials, vol. 39, no. 11, pp. 2495-2502, 2010.
[38] X. Niu and K.-L. Lin, "Effects of Al, Pr additions on the wettability and interfacial reaction of Zn–25Sn solder on Cu substrate," Journal of Materials Science: Materials in Electronics, vol. 28, no. 1, pp. 105-113, 2017.
[39] X. Niu and K.-L. Lin, "Investigations of the wetting behaviors of Zn–25Sn, Zn–25Sn–XPr and Zn–25Sn–YAl high temperature lead free solders in air and Ar ambient," Journal of Alloys and Compounds, vol. 646, pp. 852-858, 2015.
[40] X. Niu and K.-L. Lin, "The microstructure and mechanical properties of Zn-25Sn-XAl (X= 0–0.09 wt%) high temperature lead free solder," Materials Science and Engineering: A, vol. 677, pp. 384-392, 2016.
[41] W.-C. Huang and K.-L. Lin, "Effect of Ti addition on early-stage wetting behavior between Zn-25Sn-xTi solder and Cu," Journal of Electronic Materials, vol. 45, no. 12, pp. 6137-6142, 2016.
[42] Y. C. Chan and D. Yang, "Failure mechanisms of solder interconnects under current stressing in advanced electronic packages," Progress in Materials Science, vol. 55, no. 5, pp. 428-475, 2010.
[43] S. Park, R. Dhakal, L. Lehman, and E. Cotts, "Measurement of deformations in SnAgCu solder interconnects under in situ thermal loading," Acta materialia, vol. 55, no. 9, pp. 3253-3260, 2007.
[44] D. Frear, "The mechanical behavior of interconnect materials for electronic packaging," JOM, vol. 48, no. 5, pp. 49-53, 1996.
[45] X. Shi, H. Pang, W. Zhou, and Z. Wang, "Low cycle fatigue analysis of temperature and frequency effects in eutectic solder alloy," International Journal of fatigue, vol. 22, no. 3, pp. 217-228, 2000.
[46] D. Xie, Y. C. Chan, J. Lai, and I. Hui, "Fatigue life estimation of surface mount solder joints," IEEE Transactions on Components, Packaging, and Manufacturing Technology: Part B, vol. 19, no. 3, pp. 669-678, 1996.
[47] T.-S. Park and S.-B. Lee, "Mechanical fatigue tests of solder joint under mixed-mode loading cases," in Advances in Electronic Materials and Packaging 2001 (Cat. No. 01EX506), 2001: IEEE, pp. 438-443.
[48] K. Yazzie, H. Fei, H. Jiang, and N. Chawla, "Rate-dependent behavior of Sn alloy–Cu couples: Effects of microstructure and composition on mechanical shock resistance," Acta Materialia, vol. 60, no. 10, pp. 4336-4348, 2012.
[49] Y.-H. Lee and H.-T. Lee, "Shear strength and interfacial microstructure of Sn–Ag–xNi/Cu single shear lap solder joints," Materials Science and Engineering: A, vol. 444, no. 1-2, pp. 75-83, 2007.
[50] H. Zou and Z. Zhang, "Effects of aging time, strain rate and solder thickness on interfacial fracture behaviors of Sn–3Cu/Cu single crystal joints," Microelectronic Engineering, vol. 87, no. 4, pp. 601-609, 2010.
[51] X. Hu, T. Xu, L. M. Keer, Y. Li, and X. Jiang, "Shear strength and fracture behavior of reflowed Sn3. 0Ag0. 5Cu/Cu solder joints under various strain rates," Journal of Alloys and Compounds, vol. 690, pp. 720-729, 2017.
[52] C.-h. Wang, H.-h. Chen, and P.-y. Li, "Interfacial reactions of high-temperature Zn–Sn solders with Ni substrate," Materials Chemistry and Physics, vol. 136, no. 2-3, pp. 325-333, 2012.
[53] X. Li, F. Li, F. Guo, and Y. Shi, "Effect of isothermal aging and thermal cycling on interfacial IMC growth and fracture behavior of SnAgCu/Cu joints," Journal of Electronic Materials, vol. 40, no. 1, pp. 51-61, 2011.
[54] C.-W. Chang and K.-L. Lin, "Effect of Ti addition on the mechanical properties of high temperature Pb-free solders Zn–25Sn–xTi," Journal of Materials Science: Materials in Electronics, vol. 29, pp. 10962-10968, 2018.
[55] W.-T. Guo, C.-L. Liang, and K.-L. Lin, "The effects of Cu alloying on the microstructure and mechanical properties of Zn-25Sn-xCu (x= 0–1.0 wt%) high temperature Pb-free solders," Materials Science and Engineering: A, vol. 750, pp. 117-124, 2019.
[56] H. Okamoto, "Ni-Zn (Nickel-Zinc)," Journal of Phase Equilibria and Diffusion, journal article vol. 34, no. 2, pp. 153-153, April 01 2013.
[57] V. Vassiliev and V. Lysenko, "Thermodynamic evaluation of the Cu-In-Zn system," Journal of Alloys and Compounds, vol. 681, pp. 606-612, 2016.
[58] S. Fürtauer, D. Li, D. Cupid, and H. Flandorfer, "The Cu–Sn phase diagram, Part I: new experimental results," Intermetallics, vol. 34, pp. 142-147, 2013.
[59] G. Leone and H. Kerr, "Grain structures and coupled growth in Zn-Ti alloys," Journal of Crystal Growth, vol. 32, no. 1, pp. 111-116, 1976.
[60] G. Leone, P. Niessen, and H. Kerr, "The mechanism of grain refinement during solidification of Zn-Ti base alloys," Metallurgical Transactions B, vol. 6, no. 4, pp. 503-511, 1975.
[61] P. Cheng, Y. Zhao, R. Lu, H. Hou, Z. Bu, and F. Yan, "Effect of Ti addition on the microstructure and mechanical properties of cast Mg-Gd-Y-Zn alloys," Materials Science and Engineering: A, vol. 708, pp. 482-491, 2017.
[62] Y. Wang, X. Zeng, W. Ding, A. A. Luo, and A. K. Sachdev, "Grain refinement of AZ31 magnesium alloy by titanium and low-frequency electromagnetic casting," Metallurgical and Materials Transactions A, vol. 38, no. 6, pp. 1358-1366, 2007.
[63] C. Chuang, L. Tsao, H. Lin, and L. Feng, "Effects of small amount of active Ti element additions on microstructure and property of Sn3. 5Ag0. 5Cu solder," Materials Science and Engineering: A, vol. 558, pp. 478-484, 2012.
[64] E. R. Jette and F. Foote, "Precision determination of lattice constants," The Journal of Chemical Physics, vol. 3, no. 10, pp. 605-616, 1935.
[65] R. R. Pawar and V. Deshpande, "The anisotropy of the thermal expansion of α-titanium," Acta Crystallographica Section A: Crystal Physics, Diffraction, Theoretical and General Crystallography, vol. 24, no. 2, pp. 316-317, 1968.
[66] B. L. Bramfitt, "The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid iron," Metallurgical Transactions, vol. 1, no. 7, pp. 1987-1995, 1970.
[67] B. Murty, S. Kori, and M. Chakraborty, "Grain refinement of aluminium and its alloys by heterogeneous nucleation and alloying," International Materials Reviews, vol. 47, no. 1, pp. 3-29, 2002.
[68] C.-W. Chang and K.-L. Lin, "High-Temperature Mechanical Properties of Zn-Based High-Temperature Lead-Free Solders," Journal of Electronic Materials, vol. 48, no. 1, pp. 135-141, 2019.
[69] J. C. Slater, "Atomic radii in crystals," The Journal of Chemical Physics, vol. 41, no. 10, pp. 3199-3204, 1964.
[70] W.-k. Liou, Y.-W. Yen, and C.-C. Jao, "Interfacial reactions of Sn-9Zn-xCu (x= 1, 4, 7, 10) solders with Ni substrates," Journal of electronic materials, vol. 38, no. 11, pp. 2222-2227, 2009.
[71] B. Dyson, T. Anthony, and D. Turnbull, "Interstitial diffusion of copper in tin," Journal of Applied Physics, vol. 38, no. 8, pp. 3408-3408, 1967.
[72] R. Hultgren, P. D. Desai, D. T. Hawkins, M. Gleiser, and K. K. Kelley, "Selected values of the thermodynamic properties of binary alloys," National Standard Reference Data System, 1973.
[73] R. E. Reed-Hill, R. Abbaschian, and R. Abbaschian, "Physical metallurgy principles," 1973.
[74] C. Grovenor, H. Hentzell, and D. Smith, "The development of grain structure during growth of metallic films," Acta Metallurgica, vol. 32, no. 5, pp. 773-781, 1984.
[75] W. D. C. Jr., Materials Science and Engineering - An Introduction, 7 ed. John Wiley & Son, Inc., 2007.
[76] W. C. Oliver and G. M. Pharr, "An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments," Journal of materials research, vol. 7, no. 6, pp. 1564-1583, 1992.
[77] Y. V. Milman, B. Galanov, and S. Chugunova, "Plasticity characteristic obtained through hardness measurement," Acta metallurgica et materialia, vol. 41, no. 9, pp. 2523-2532, 1993.
[78] W. Köster and H. Franz, "Poisson's ratio for metals and alloys," Metallurgical reviews, vol. 6, no. 1, pp. 1-56, 1961.
[79] L. Lee, É. Régis, S. Descartes, and R. R. Chromik, "Fretting wear behavior of Zn–Ni alloy coatings," Wear, vol. 330, pp. 112-121, 2015.
[80] K. M. Kumar, V. Kripesh, L. Shen, K. Zeng, and A. A. Tay, "Nanoindentation study of Zn-based Pb free solders used in fine pitch interconnect applications," Materials Science and Engineering: A, vol. 423, no. 1-2, pp. 57-63, 2006.
[81] S. S. Zumdahl and D. J. DeCoste, Chemical principles. Nelson Education, 2012.
[82] D. C. Harris, Quantitative chemical analysis. Macmillan, 2010.