本研究的目的在探討冷卻速率差異(慢冷0.008°C/s-快冷100°C/s)對Sn-3.0Ag-0.5Cu及Sn-3.8Ag-0.7Cu(簡稱SAC305、SAC387)無鉛銲料的金屬間化合物Ag3Sn與Cu6Sn5形貌變化與組織微硬度之影響。並使用拉伸與熱儲存試驗來評估不同冷卻速率下，無鉛銲料拉伸強度性質與時效後對微結構的影響。
研究結果顯示，冷卻速率對金屬間化合物凝固成長時間有顯著的影響，造成Ag3Sn化合物尺寸及形貌上的變化。無鉛銲料隨冷卻速率下降，Ag3Sn化合物形貌變化:顆粒狀→針狀→板片狀，以快速冷卻情況下，可得到共晶組織最為細緻，快冷下Ag3Sn化合物顆粒平均直徑尺寸約略為0.2µm，使得整體組織更為均勻。而在快冷情況下，SAC銲料內部不易發現顆粒狀的Cu6Sn5，隨冷速的下降，SAC305於空冷(CR:2.09°C/s)可觀察到Cu6Sn5化合物，而SAC387的Cu與Ag含量較高，於P4位置(CR1:9.33°C/s)即可發現Cu6Sn5化合物存在，主要形貌有針狀、棒狀及板片狀。拉伸強度隨Ag3Sn化合物粗大化而逐漸下降，其中SAC305拉伸強度由原本60.8MPa降至39.5MPa。由於高Ag含量的無鉛銲料SAC387於凝固過程中，內部會先析出初析Ag3Sn化合物，為巨大板片狀的不規則形貌，反而成為缺陷所在，裂紋易由此開裂，在拉伸強度及延性方面皆不及SAC305銲料。
綜合本研究結果顯示冷卻速率與Ag含量對於凝固過程中Ag3Sn化合物形貌、微硬度及拉伸強度都有顯著的影響。快速的冷卻速率與微量銀元素添加，將使Ag3Sn化合物具有較佳形貌，使無鉛銲料擁有良好的機械性質。

Effect of the different cooling rate (from 0.008 to 100°C/s) on the morphological evolution of the Ag3Sn, Cu6Sn5 and β-Sn formed during the solidification of Sn-3Ag-0.5Cu (SAC305) and Sn-3.8Ag-0.7Cu (SAC387) solder was investigated. The tensile tests and high temperature storage tests were also used to estimate the tensile strength and thermal influence of microstructure under different cooling rates.
Experimental results showed that cooling rate has a significant effect on the solidification time, and therefore influences both the size and the morphology of the eutectic Ag3Sn compound. Specifically, as the cooling rate is reduced, the Ag3Sn compound exhibits a coarsening evolution: particle-like → needle-like → plate-like. The Ag3Sn particles have average diameters of about 0.2µm by fast cooling. The tensile strength is reduced by the coarsening of Ag3Sn. The tensile strength for SAC305 tensile specimens decreased from 60.8MPa to 39.5MPa. SAC387 solder possesses more additional Ag and Cu than SAC305, and its tensile strength is degraded seriously due to the formation of coarse primary Ag3Sn compounds. SAC387 under slower cooling, cracks tend to occur at plate-like primary Ag3Sn compound and extend into the matrix. As a result, such a large and brittle primary compound precipitation is harmful to strength and ductility of solders.
In summary, Ag content and cooling rates have influences on morphological evolution of Ag3Sn compound where faster cooling and/or less Ag addition seem to have beneficial effect on morphological evolution of Ag3Sn and mechanical properties as well.

1. L.J. Turbini, G.C. Munie, D. Bernier, J. Gamalski, and D.W. Bergman, "Examining the environmental impact of lead-free soldering alternatives," Electronics Packaging Manufacturing, IEEE Transactions, Vol.24 (1), 2001, pp. 4-9.
2. T. Brady, M. Garner, and V. Gupta, "Green Design : Lead-Free Technologies," Intel Papers, 2002.
3. P. Cox and G. Drys, "Directive 2002/95/EC of the european parliament and of the council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment," Official Journal of the European Union, 2003.
4. IPC Roadmap: A Guide for Assembly of Lead-Free Electronics, 4th Draft, 2000.6.
5. M. McCormack, H. Chen, G. Kammlott, and S. Jin, "Significantly improved mechanical properties of Bi-Sn solder alloys by Ag-doping," Journal of Electronic Materials, Vol.26 (8), 1997, pp. 954-958.
6. H.T. Lee, M.H. Chen, H.M. Jao, and C.J. Hsu, "Effect of adding Sb on microstructure and adhesive strength of Sn-Ag solder joints," Journal of Electronic Materials, Vol.33 (9), 2004, pp. 1048-1054.
7. H.T. Lee, T.L. Liao, and M.H. Chen. "Study on microstructure and shear strength of Sn-Ag-Sb solder joints," Electronic Materials and Packaging, 2001, pp. 315-322.
8. H.T. Lee, H.S. Lin, C.S. Lee, and P.W. Chen, "Reliability of Sn-Ag-Sb lead-free solder joints," Materials Science and Engineering: A, Vol.407 (1-2), 2005, pp. 36-44.
9. M. Muller, S. Wiese, and K.J. Wolter. "Influence of cooling rate and composition on the solidification of SnAgCu solders," Electronics Systemintegration Technology Conference, Vol.2, 2006, pp. 1303-1311.
10. K. Kim, S. Huh, and K. Suganuma, "Effects of cooling speed on microstructure and tensile properties of Sn-Ag-Cu alloys," Materials Science and Engineering A, Vol.333 (1-2), 2002, pp. 106-114.
11. J.J. Sundelin, S.T. Nurmi, T.K. Lepisto, and E.O. Ristolainen, "Mechanical and microstructural properties of SnAgCu solder joints," Materials Science and Engineering: A, Vol.420 (1-2), 2006, pp. 55-62.
12. K. Suganuma, "Interface phenomena in lead-free soldering," proceedings. EcoDesign '99: first international symposium on environmentally conscious design and inverse manufacturing 1999, pp.620-625, Japan, 1999.2.1-3
13. NC257-2 SAC 305, Manufacturing and Distribution Worldwide.
14. I. Anderson, J. Walleser, and J. Harringa, "Observations of nucleation catalysis effects during solidification of SnAgCuX solder joints," Journal of the Minerals, Metals and Materials Society, Vol.59 (7), 2007, pp. 38-43.
15. IPC/JEDEC J-STD-020C , 2004.7.
16. N.C. Lee, "Getting Ready for Lead-free Solders*," Soldering & Surface Mount Technology, Vol.9 (2), 1997, pp. 65-69.
17. M. Abtew and G. Selvaduray, "Lead-free solders in microelectronics," Materials Science and Engineering: R: Reports, Vol.27 (5-6), 2000, pp. 95-141.
18. B. Richards, C. Levoguer, and C. Hunt, "An analysis of the current status of lead-free soldering," DTI Report, 1999.
19. D. Suraski and K. Seelig, "The current status of lead-free solder alloys," Electronics Packaging Manufacturing, IEEE Transactions, Vol.24 (4), 2001, pp. 244-248.
20. 胡順源, “Sn-Ag-xSb無鉛錫銲接點與Au/Ni-P/Cu金屬層之界面微結構與剪切強度研究,” 國立成功大學機械工程研究所, 碩士論文, 2003.
21. A.Z. Miric and A. Grusd, "Lead-free alloys," Soldering & Surface Mount Technology, Vol.10 (1), 1998, pp. 19-25.
22. S. Choi, J. Lee, F. Guo, T. Bieler, K. Subramanian, and J. Lucas, "Creep properties of Sn-Ag solder joints containing intermetallic particles," Journal of the Minerals, Metals and Materials Society, Vol.53 (6), 2001, pp. 22-26.
23. W. Yang, R.W. Messler, and L.E. Felton, "Microstructure evolution of eutectic Sn-Ag solder joints," Journal of Electronic Materials, Vol.23 (8), 1994, pp. 765-772.
24. K. Suganuma, S.H. Huh, K. Kim, H. Nakase, and Y. Nakamura, "Effect of Ag content on properties of Sn-Ag binary alloy solder," Materials Transactions-JIM, Vol.42 (2), 2001, pp. 286-291.
25. W. Yang, L.E. Felton, and R.W. Messler, "The effect of soldering process variables on the microstructure and mechanical properties of eutectic Sn-Ag/Cu solder joints," Journal of Electronic Materials, Vol.24 (10), 1995, pp. 1465-1472.
26. H. BakerandH. Okamoto, "Alloy phase diagrams," ASM International, ASM Handbook., Vol.3, 1992, pp. 501.
27. J.K. Lin, A. De Silva, D. Frear, Y. Guo, S. Hayes, J.W. Jang, L. Li, D. Mitchell, B. Yeung, and C. Zhang, "Characterization of lead-free solders and under bump metallurgies for flip-chip package," Electronics Packaging Manufacturing, IEEE Transactions, Vol.25 (4), 2002, pp. 300-307.
28. J. Shen, Y. Liu, and H. Gao, "Formation of bulk Cu6Sn5 intermetallic compounds in Sn-Cu lead-free solders during solidification," Journal of Materials Science, Vol.42 (14), 2007, pp. 5375-5380.
29. W. Chen, R. Tsai, Y. Lin, and C. Kao, "Effect of copper concentration on the solid-state aging reactions between tin-copper lead-free solders and nickel," Journal of SMT, Vol.15 (4), 2002.
30. http://www.metallurgy.nist.gov/phase/solder/solder.html.
31. J. Freer and J. Morris, "Microstructure and creep of eutectic indium/tin on copper and nickel substrates," Journal of Electronic Materials, Vol.21 (6), 1992, pp. 647-652.
32. S.K. Kang and A.K. Sarkhel, "Lead (Pb)-free solders for electronic packaging," Journal of Electronic Materials, Vol.23 (8), 1994, pp. 701-707.
33. Y. Kariya and M. Otsuka, "Mechanical fatigue characteristics of Sn-3.5Ag-X (X=Bi, Cu, Zn and In) solder alloys," Journal of Electronic Materials, Vol.27 (11), 1998, pp. 1229-1235.
34. W. Allen and J. Perepezko, "Constitution of the Tin-Antimony system," Scripta Metallurgica, Vol.24 (11), 1990, pp. 2215-2220.
35. M. Beshai, S. Habib, A. Yassein, G. Saad, and E.N. Hasab, "Effect of SnSb particle size on creep behaviour under power law regime of Sn 10% Sb alloy," Crystal Research and Technology, Vol.34 (1), 1999, pp. 119-126.
36. P. Vianco, K. Erickson, and P. Hopkins, "Solid state intermetallic compound growth between copper and high temperature, tin-rich solders part I: experimental analysis," Journal of Electronic Materials, Vol.23 (8), 1994, pp. 721-727.
37. R.J. McCabe and M.E. Fine, "Creep of tin, Sb-solution-strengthened tin and SbSn-precipitate-strengthened tin," Metallurgical and Materials Transactions A, Vol.33 (5), 2002, pp. 1531-1539.
38. Y. Miyazawa, T. Ariga, “Microstructural change and hardness of lead free solder alloys,” Environmentally Conscious Design and Inverse Manufacturing, 1999. Proceedings. EcoDesign 99: First Inrernational Symposium, 1999, pp.616-619
39. Y. Miyazawa and T. Ariga, "Influences of aging treatment on microstructure and hardness of Sn-(Ag, Bi, Zn) eutectic solder alloys: Special issue on basic science and advanced technology of lead-free electronics packaging," Materials Transactions-JIM, Vol.42 (5), 2001, pp. 776-782.
40. M. McCormack, S. Jin, H. Chen, and D. Machusak, "New lead-free, Sn-Zn-In solder alloys," Journal of Electronic Materials, Vol.23 (7), 1994, pp. 687-690.
41. C.F. Chen, S.K. Lahiri, and P. Yuan, "An Intermetallic study joints with Sn-Ag-Cu lead-free solder," Electronics Packing Technology Conference, 2000, pp. 72-81.
42. T. Lee, W. Choi, K. Tu, J. Jang, S. Kuo, J. Lin, D. Frear, K. Zeng, and J. Kivilahti, "Morphology, kinetics and thermodynamics of solid-state aging of eutectic SnPb and Pb-free solders (Sn-3.5Ag, Sn-3.8Ag-0.7Cu and Sn-0.7Cu) on Cu," Journal of Materials Research, Vol.17 (2), 2002, pp. 291-301.
43. Metallurgy Division of the Material Science and Engineering Laboratory, "Ag-Cu-Sn phase diagram & computational thermodynamics,” Date: 2006-04-11.
44. K. Kim, S. Huh, and K. Suganuma, "Effects of intermetallic compounds on properties of Sn-Ag-Cu lead-free soldered joints," Journal of Alloys and Compounds, Vol.352 (1-2), 2003, pp. 226-236.
45. M. Yeh, "Effects of indium on the mechanical properties of ternary Sn-In-Ag solders," Metallurgical and Materials Transactions A, Vol.34 (2), 2003, pp. 361-365.
46. J.M. Song and K.L. Lin, "Double peritectic behavior of Ag-Zn intermetallics in Sn-Zn-Ag solder alloys," Journal of Materials Research, Vol. 19, No.9, 2004, pp.2719-2724
47. Y. Kariya and M. Otsuka, "Effect of bismuth on the isothermal fatigue properties of Sn-3.5 mass% Ag solder alloy," Journal of Electronic Materials, Vol.27 (7), 1998, pp. 866-870.
48. 饒慧美, “添加Sb、Cu對無鉛銲料Sn-Ag銲點之機械性質及微結構研究,” 國立成功大學機械研究所, 碩士論文, 2000.
49. 楊傳鏈, ”添加Sb 對Sn-Ag 無鉛銲料銲點微結構與剪切強度之影響,” 國立成功大學機械工程研究所, 碩士論文, 2000.
50. 宋立文, "冷卻速率及Cu/Ni-P/Au金屬層對 Sn-Ag-xSb無鉛銲錫接點之剪切強度特性及界面微結構的影響," 國立成功大學機械研究所, 碩士論文, 2004.
51. 廖天龍, “添加Sb對Sn-Ag無鉛銲料之銲點剪切強度研究,” 國立成功大學機械研究所, 碩士論文, 2001.
52. H.T. Lee and Y.F. Chen, "Evolution of Ag3Sn intermetallic compounds during solidification of eutectic Sn-3.5 Ag solder," Journal of Alloys and Compounds, Vol.509, 2011, pp.2510-2517
53. Kurz, W. Fisher, D. J.,“Fundamentals of Solidification,” 4th rev. ed., 1998.
54. 陳明宏, “添加Sb對Sn-Ag無鉛銲料銲點冶金性質與機械性質之研究,” 國立成功大學機械研究所, 博士論文, 2003.
55. J. Sigelko, S. Choi, K. Subramanian, J.P. Lucas, and T. Bieler, "Effect of cooling rate on microstructure and mechanical properties of eutectic Sn-Ag solder joints with and without intentionally incorporated Cu 6 Sn 5 reinforcements," Journal of Electronic Materials, Vol.28 (11), 1999, pp. 1184-1188.
56. S.K. Kang, D.Y. Shih, N. Donald, W. Henderson, T. Gosselin, A. Sarkhel, N. Charles Goldsmith, K.J. Puttlitz, and W.K. Choi, "Ag3Sn plate formation in the solidification of near-ternary eutectic Sn-Ag-Cu," Journal of the Minerals, Metals and Materials Society, Vol.55 (6), 2003, pp. 61-65.
57. 王照中, "電子產品之溫度循環試驗規範簡介," 電子檢測與品管, No.42, 2000.4, pp.44-48.
58. 陳曉薇, “溫度與應變速率對Sn-Ag基底銲點結合強度影響之研究,” 國立成功大學機械研究所, 碩士論文, 2009.
59. F. Ochoa, X. Deng, and N. Chawla, "Effects of cooling rate on creep behavior of a Sn-3.5 Ag alloy," Journal of Electronic Materials, Vol.33 (12), 2004, pp. 1596-1607.
60. F. Ochoa, J. Williams, and N. Chawla, "Effects of cooling rate on the microstructure and tensile behavior of a Sn-3.5 wt.% Ag solder," Journal of Electronic Materials, Vol.32 (12), 2003, pp. 1414-1420.
61. H.Y. Lu, H. Balkan, and K.Y.S. Ng, "Effect of Ag content on the microstructure development of Sn-Ag-Cu interconnects," Journal of Materials Science: Materials in Electronics, Vol.17 (3), 2006, pp. 171-178.
62. 陳銀發, “添加Cu對Sn-Ag-Sb無鉛銲料銲點微結構與剪切強度之影響,” 國立成功大學機械研究所, 碩士論文, 2005.
63. K. Jackson and J. Hunt, "Lamellar and rod eutectic growth," AIME Met.
Soc. Trans., Vol.236, 1966, pp. 1129-1142.
64. NC254 SAC 305, Manufacturing and Distribution Worldwide.
65. P. Thevoz, J. Desbiolles, and M. Rappaz, "Modeling of equiaxed microstructure formation in casting," Metallurgical and Materials Transactions A, Vol.20 (2), 1989, pp. 311-322.
66. N. SaundersandA. Miodownik, "The Cu-Sn (copper-tin) system," Journal of Phase Equilibria, Vol.11 (3), 1990, pp. 278-287.
67. H.T. Lee, W.Y. Huang, and Y.F. Chen, "Influence of Cu addition on intermetallic compound formation and microstructure of Sn-3Ag-2Sb-xCu solder joints," Science and Technology of Welding Joining, Vol.13 (8), 2008, pp. 781-790.
68. H.T. Lee, M.H. Chen, and H.M. Jao, "Influence of copper addition on adhesive strength of Sn-3Ag-1.5 Sb solder joints," Science and Technology of Welding and Joining, Vol.9 (6), 2004, pp. 555-559.