本研究係探討本實驗開發之特定組成錫鋅銀鋁鎵五元銲錫合金(Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga)，於通電條件下，電遷移對銲錫線材之拉伸機械性質的影響，通電實驗的條件為溫度70℃、電流密度2.5 x 103A/cm2，並另外在與通電條件相同溫度下進行時效熱處理，以比對與電遷移實驗之差異。
拉伸試驗結果顯示，經通電處理之銲錫線材的最大拉伸強度皆小於熱處理之銲錫線材的最大拉伸強度，文獻結果顯示通電的純錫線，其晶粒會產生旋轉重新排列以降低電阻，且沿著電子流方向排列的β錫晶粒其彈性係數較低，推測此可能為造成本實驗通電之銲錫線的拉伸強度較小的原因。但從微觀結構上的並無法觀察到β錫的變化 ，為了了解β錫的變化，嘗試以X-ray繞射分析觀察同一試片之富錫相與富鋅相的變化，於通電與熱處理四、七、十三天，X-ray繞射分析結果顯示，不論是通電或熱處理，富鋅相的訊號皆增強，且無某一特定優選結晶面，然而富錫相的訊號的消長情況卻因通電或熱處理而有所不同。
而銲錫合金之機械性質表現與其微觀組織息息相關，銲錫顯微結構顯示，不論是通電或熱處理之銲錫線，銲錫基地中會出現圓鈍化的AgZn3介金屬化合物、針棒狀的富鋅相與β錫的組織。因此進一步針對同一試片同一位置於不同通電與熱處理天數，觀察微觀結構的變化，發現AgZn3介金屬化合物無太大的改變，富鋅相有明顯成長粗大化的趨勢且於七天後此趨勢趨於緩和，此結果與錫鋅銀鋁鎵五元銲錫合金之最大拉伸強度在熱處理與通電七至十天後趨於一穩定值相符合。
故富鋅相的成長為通電與熱處理試片之最大拉伸強度下降的主因，而通電試片之拉伸強度小於熱處理試片之拉伸強度主要為富錫相的消長不同所致。

The present work investigated the effect of electromigration on the tensile properties of the Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga alloy. The current density and the testing temperature were kept at ~2.5 x 103A/cm2 and 70°C, respectively. Besides, in order to understand the change in tensile properties of Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga alloy were caused by the current or temperature, solder wires were separately treated thermally and kept under current stressing.
The results showed that the ultimate tensile strength of all solder wires under current stressing was lower than that of the solder wires treated thermally. The major causes, as described in the earlier research, for lower ultimate tensile strength of current stressed solder wires were due to the rotation of β-Tin grains to reduce resistance under high current density and smaller elastic modulus of β-Tin along a-axis than c-axis. However, the changes in β-Tin were not observed in our SEM experiments. In order to understand the changes in β-Tin during current stressing or thermal treatment, X-ray diffraction was used to analyze the specimens after current stressing and thermal treatment for four, seven and thirteen days. The results showed that the changes in intensities of β-Tin phases were different between the specimens undergo current stressing and the specimens undergo thermal treatment. Further, all of the intensities of Zinc-rich phases were found to be stronger after longer thermal treatment and current stressing. So, there was not any preferred orientation of Zinc-rich phases.
It is known that the mechanical behaviors of the solder are related to their microstructures. As observed in SEM, microstructure of the Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga solder exhibited needle Zn-rich phase and coarsened AgZn3 distributed in the Sn matrix. Further, the observation of same specimens after current stressing and thermal treatment revealed that the AgZn3 did not change with time, but the Zn-rich phases coarsened fast in the beginning, and became slow after seven days.
The coarsened Zinc-rich phases may be the major cause for lower ultimate tensile strength of specimens after current stressing or thermal treatment. However, lower ultimate tensile strength after current stressing than thermal treatment may be caused by the changes in β-Tin.

1. H. Y. Chang, S. W. Chen, and D. S. H. Wong, “Determination of Reactive Wetting Properties of Sn, Sn-Cu, Sn-Ag, and Sn-Pb Alloys Using a Wetting BalanceTechnique”, Journal of Materials Research, Vol, 18, 2003, pp. 1420-1428.
2. S. Jin, “Developing Lead-Free Solders: A challenge and opportunity”, Journal of The Minerals Metals & Materials Society, Vol. 45, 1993, p.13.
3. H. Ma and J. C. Suhling, “A Review of Mechanical Properties of Lead-Free Solders for Electronic Packaging”, Journal of Materials Science, Vol. 44, 2009, pp. 1141-1158.
4. N. C. Lee, “Getting Ready for Lead-free Solders”, Soldering & Surface Mount Technology, Vol. 9, 1997, pp. 65-69.
5. M. Mccormack and S. Jin “New Lead-Free Solder”, Journal of Electronic Materials, Vol. 23, 1994, pp. 635-640.
6. J. Glazer, “Metallurgy of Low Temperature Pb-Free Solders for Electronic Assembly”, International Materials Reviews, Vol. 40, 1995, pp. 65-93.
7. D. J. Xie, “A New Experimental Method to Evaluate Creep Fatigue Life of Flip-Chip Solder Joints with Underfill”, Microelectronics Reliability, Vol. 40, 2000, pp. 1191-1198.
8. L. Valdevit, V. Khanna, A. Sharma, S. S. Jayantha, D. Questad, and K. Sikka, “Organic Substrates for Flip-Chip Design: A Thermo-Mechanical Model That Accounts for Heterogeneity and Anisotropy”, Microelectronics Reliability, Vol. 48, 2008, pp. 245-260.
9. T. Takemoto and M. Miyazaki, “Effect of Excess Temperature above Liquidus of Lead-Free Solders on Wetting Time in a Wetting Balance Test”, Materials Transactions, Vol. 42, 2001, pp. 745-750.
10. M. Abtew, G. Selvaduray, “Lead-free Solders in Microelectronics”, Materials Science and Engineering, Vol. 27, 2000, pp. 95-141.
11. A. Z. Miric, “Lead-free Alloys”, Soldering & Surface Mount
Technology, Vol. 10, 1998, pp. 19-25.
12. K. Suganuma, “Advances in Lead-Free Electronics Soldering”, Current Opinion in Solid State and Materials Science, Vol. 5, 2001, pp. 55-64.
13. I. Shohji1, K. Yasuda, and T. Takemoto, “Estimation of Thermal Fatigue Resistances of Sn-Ag and Sn-Ag-Cu Lead-Free Solders Using Strain Rate Sensitivity Index”, Materials Transactions, Vol. 46, 2005, pp. 2329-2334.
14. I. E. Anderson, “Development of Sn-Ag-Cu and Sn-Ag-Cu-X alloys for Pb-Free Electronic Solder Applications ”, Journal of Materials Science: Materials in Electronics, Vol. 18, 2007, pp. 55-76.
15. J. Liang, N. Dariavach, P. Callahan, and D. Shangguan, “Metallurgy and Kinetics of Liquid-Solid Interfacial Reaction during Lead-Free Soldering”, Vol. 47, 2006, pp. 317-325.
16. B. Huang, A. Dasgupta, and N. C. Lee, “Effect of Sn-Ag-Cu Composition on Soldering Performance”, Soldering & Surface Mount Technology, Vol. 17, 2005, pp. 9-19.
17. T. B. Massalski, “Binary Alloy Phase Diagrams”, ASM, Ohio, 1986, p.1401.
18. T. B. Massalski, “Binary Alloy Phase Diagrams”, ASM, Ohio, 1986, p. 540.
19. H. Kabassis, J. W. Rutter, and W. C. Winegard, “Phase Relationships in Bi-In-Sn Alloy Systems”, Materials Science & Technology, Vol. 2, 1986, pp. 985-988.
20. P. J. Shang, Z. Q. Liu, D. X. Lia, and J. K. Shanga, “Bi-Induced Voids at the Cu3Sn/Cu Interface in Eutectic SnBi/Cu Solder Joints”, Scripta Materialia, Vol. 58, 2008, pp. 409-412.
21. T. B. Massalski, “Binary Alloy Phase Diagrams”, ASM, Ohio, 1986, p. 2086.
22. M. Mccormack and S. Jin, “Improved Mechanical Properties in New, Pb-Free Solder Alloys”, Journal of Electronic Materials, Vol. 23, 1994, pp. 715-720.
23. K. Suganuma and K. Niihara, “Wetting and Interface Microstructure Between Sn-Zn Binary Alloys and Cu”, Journal of Materials Research, Vol. 13, 1998, pp. 2859-2865.
24. K. I. Chen and K. L. Lin, “The Microstructures and Mechanical Properties of the Sn-Zn-Ag-Al-Ga Solder Alloys—the Effect of Ag”, Journal of Electronic Materials, Vol. 31, 2002, pp. 861-867.
25. C. L. Shih and K. L. Lin, “Wetting Interaction between Sn-Zn-Ag Solders and Cu”, Journal of Electronic Materials, Vol. 32, 2003, pp. 95-100.
26. T. P. Liu and K. L. Lin, “High-Temperature Oxidation of a Sn-Zn-Al Solder”, Oxidation of Metals, Vol. 50, 1998, pp. 255-267.
27. Y. C. Wang and K. L. Lin, “Wetting Interaction of Pb-Free Sn-Zn-Al Solders on Metal Plated Substrate”, Journal of Electronic Materials, Vol. 27, 1998, pp. 1205-1210.
28. K. I. Chen, S. C. Cheng, S. Wu, and K. L. Lin, “Effects of Small Additions of Ag, Al, and Ga on the Structure and Properties of the Sn–9Zn Eutectic Alloy”, Journal of Alloys and Compounds, Vol. 416, 2006, pp. 98-105.
29. K. I. Chen and K. L. Lin, “The Microstructures and Mechanical Properties of the Sn-Zn-Ag-Al-Ga Solder Alloys—The Effect of Ga”, Journal of Electronic Materials, Vol. 32, 2003, pp. 1111-1116.
30. N. S. Liu and K. L. Lin, “The Effect of Ga Content on the Wetting Reaction and Interfacial Morphology Formed between Sn-8.55Zn-0.5Ag-0.1Al-xGa Solders and Cu”, Scripta Materialia, Vol. 54, 2006, pp. 219-224.
31. N. S. Liu and K. L. Lin, “Microstructure and Mechanical Properties of Low Ga Content Sn-8.55Zn-0.5Ag-0.1Al-xGa solders”, Scripta Materialia, Vol. 52, pp. 369-374.
32. W. D. Callister, Materials Science and Engineering an Introduction, 6th edition, John Wiley and Sons, New York (2003) pp. 111-140.
33. Thomas H. Courtney, Mechanical Behavior of Materials, 2nd edition, McGraw Hill Higher Education, (2000) pp. 1-38, and pp. 293-347.
34. I. A. Blech and E. Kinsborn, “Direct Transmission Electron Microscope Observation of Electrotransport in Aluminum Thin Film”, Applied Physics Letters, Vol. 11, 1967, pp. 263-266
35. V. B. Fiks, “On the Mechanism of the Ions in Metals”, Soviet Physics-Solid State, Vol. 1, 1959, pp. 14-28.
36. H. B. Huntington and A. R. Grone, “Current-Induced Maker Motion in Gold Wires”, Journal of Physics and Chemistry of Solids, Vol. 20, 1961, pp. 76-87.
37. C. Bosvieux and J. Friedel, “Sur L，Elctrolyse Des Alliages Metalliques”, Journal of Physics and Chemistry of Solids, Vol. 23, 1962, pp. 123-136.
38. R. S. Sorbello, “A Pseudopotential Based Theroy of the Driving Forces for Electromigration in Metals”, Journal of Physics and Chemistry of Solids, Vol. 34, 1973, pp. 937-950.
39. H. B. Huntington, “Diffusion in Solids : Recent Developments”, edited by A. S. Nowick and J. J. Burton, Academic Press, New York, 1975, pp. 303-352.
40. M. Y. Hsieh and H. B. Huntington, “Electromigration of Noble-Metals in Lead”, Bulletin of The American Physical Society, Vol. 20, 1975, pp. 443-443.
41. D. A. Golopentia and H. B. Huntington,“Study of Electromigration of Nickel in Lead”, Journal of Physics and Chemistry of Solids, Vol. 39, 1978, pp. 975-984.
42. M. Y. Hsieh and H. B. Huntington, “Electromigration of Fast Diffusers in Lead”, Journal of Nuclear Materials, Vol. 69, 1978, pp. 561-563.
43. M. Y. Hsieh and H. B. Huntington, “Electromigration of Copper in Lead”, Journal of Physics and Chemistry of Solids, Vol. 39, 1978, pp. 867-871.
44. E. C. C. Yeh, W. J. Choi, and K. N. Tu, P. Elenius, and H. Balkan, “Current-Crowding-Induced Electromigration Failure in Flip Chip Solder Joints”, Applied Physics Letters, Vol. 80, 2002, pp. 580-583.
45. B. H. L. Chao, X. F. Zhang, S. H. Chae, and P. S. Ho, “Recent Advances on Kinetic Analysis of Electromigration Enhanced Intermetallic Growth and Damage Formation in Pb-Free Solder Joints”, Microelectronics Reliability, Vol. 49, 2009, pp. 253-263.
46. M. H. R. Jen, L. C. Liu, and Y. S. Lai, “Electromigration Test on Void Formation and Failure Mechanism of FCBGA Lead-Free Solder Joints”, IEEE Transactions on Components and Packaging Technologies, Vol. 32, 2009, pp. 79-88.
47. S. S. Ha, J. W. Kim, J. W. Yoon, S. O. Ha and S. B. Jung, “Electromigration Behavior in Sn-37Pb and Sn-3.0Ag-0.5Cu Flip-Chip Solder Joints under High Current Density”, Journal of Electronic Materials, Vol. 38, 2009, pp. 70-77.
48. C. Y. Liu, J. T. Chen, Y. C. Chuang, L. Ke, and S. J. Wang, “Electromigration-Induced Kirkendall Voids at the Cu/Cu3Sn Interface in Flip-Chip Cu/Sn/Cu Joints”, Applied Physics Letters, Vol. 90, 2007.
49. C. W. Huang and K. L. Lin, “Microstructures and Mechanical Properties of Sn-8.55Zn-0.45Al-XAg Solders”, Journal of Materials Research, Vol.18, 2003, pp. 1528-1534.
50. J. R. Lloyd, “Electromigration Induced Resistance Decrese in Sn Conductors ”, Journal of Applied Physics, Vol. 94, 2003, pp. 6483-6486.
51. A. T. Wu, K. N. Tu, J. R. Lloyd, and C. R. Kao,“Electromigration- Induced Microstructure Evolution in Tin Studied by Synchrotron Microdiffraction”, Applied Physics Letters, Vol.85, 2004, pp. 2490-2492.
52. J. A. Rayne and B. S. Chandrasekhar,“Elastic Constants of β Tin from 4.2°K to 300°K”, Physical Review, Vol.120, 1960, pp. 1658-1663.
53. J. M. Song , G. F. Lan, T. S. Lui, and L. H. Chen,“Microstructure and Tensile Properties of Sn-9Zn-xAg Lead-Free Solder Alloys”, Scripta Materialia, Vol.48, 2003, pp. 1047–1051.
54. T. B. Massalski, “Binary Alloy Phase Diagrams”, ASM, Ohio, 1986, p. 86.
55. J. M. Song and K. L. Lin, “Behavior of Intermetallics in Liquid Sn-Zn-Ag Solder Alloys”, Journal of Materials Research, Vol.18, 2003, pp. 2060-2067.
56. P. A. Swarthmore, Powder diffraction file, Inorganic, in: International Centre for Diffraction Data, 1991, p. 496 (Set 25 to 26).
57. T. C. Hsuan and K. L. Lin, “Effects of Aging Treatment on Mechanical Properties and Microstructure of Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga Solder”, Materials Science and Engineering A, Vol.456, 2007, pp. 202–209.
58. P. A. Swarthmore, Powder diffraction file, Inorganic and Organic, in: International Centre for Diffraction Data, 1991, p. 268 (Set 1 to 8).
59. K. Toman, and M. Simerka, “The Deformation Texture of β-Tin. I. Compression Texture”, Czechosl. Journ. Phys., Vol. 8, 1958, pp. 94-99.