熱電材料能利用它的材料特性將熱能與電能互相轉換，在廢熱回收方面極具發展潛力。然而，熱電元件製作成模組過程中，在熱電材料與電極間的接合技術和防止元素擴散上是一大挑戰。本研究使用中溫段的PbTe和PbAgTe熱電材料，以電鍍方式沉積Ni擴散阻障層來防止元素擴散，並且透過SnAgTi銲片於真空度2×10-2 torr及溫度400℃的條件，持溫20分鐘與銅電極進行真空軟銲接合。另一方面，以PbTe熱電材料搭配AgCuTi銲片，於580℃真空環境下持溫一小時與銅電極進行固態擴散接合。最後將各成功接合的實驗試片，分別進行300℃至500℃的短時效測試與微觀組織觀察及電性量測。
實驗結果顯示，上述實驗條件可將PbTe/Ni/SnAgTi/Cu與PbAgTe/Ni/SnAgTi/Cu兩種系統成功接合，並且均可在300℃持溫30分鐘時效條件下，維持良好的接合界面情形。以及PbTe/Ni/AgCuTi/Cu系統亦依上段實驗參數下接合成功，更可在時效溫度高達500℃時，並持溫30分鐘下保持良好界面狀態。另外，於25℃環境溫度下，在PbTe/Ni/SnAgTi與PbAgTe/Ni/SnAgTi/Cu系統所測得的電阻值，均隨著時效處理溫度提高而上升。然而，在PbTe/Ni/AgCuTi系統所測得的電阻值，則是隨著時效處理溫度提高而下降。

Thermoelectric materials featuring the advantage of energy interconvertibility between heat and electrical energy shows a great potential on the application of waste heat recovery. However, the element inter-diffusion between thermoelectric materials and electrode during bonding process is a major challenge for module production. In this study, Ni diffusion barrier was deposited by electroplating on intermediate-temperature PbTe and PbAgTe thermoelectric materials to prevent the element diffusion. The bonding process for SnAgTi filler and copper electrode was carried out at 400℃ for 20 minutes under vacuum with a pressure of 2×10-2 torr. On the other hand, the high-temperature AgCuTi filler was also used for the investigation of solid-state diffusion bonding at a high temperature of 580℃for 1 hour under vacuum. Finally, the bonding samples were evaluated by short-time aging test and electrical measurement over the temperature range from 300℃ to 550℃. The cross-sectional structure was observed by scanning electron microscope.
The experimental results demonstrate that the stack of PbTe/Ni/SnAgTi/Cu and PbAgTe/Ni/SnAgTi/Cu can be successfully bonded below 450℃. These samples with appropriated bonding conditions also maintain good bonding stability at an ageing temperature of 300℃ for 30 minutes. Another bonding stack of PbTe/Ni/AgCuTi/Cu even obtained a well-bonded interface with increasing aging temperature up to 500℃ for 30 minutes. Besides, it is worth to note that the interface resistance for the bonding structure of PbTe/Ni/SnAgTi/Cu and PbAgTe/Ni/SnAgTi/Cu raised with increasing aging temperature. On the contrary, the PbTe/Ni/AgCuTi/Cu structure based on diffusion bonding approach shows a reverse trend that was evident in a lowered interface resistance with relevant increase in aging temperature.

【1】 經濟部能源局，中華民國101年能源統計手冊，台灣，2012。
【2】http://oee.nrcan.gc.ca/sites/oee.nrcan.gc.ca/files/pdf/
commercial/password/downloads/EMS_20_waste_heat_recovery.pdf.
【3】 F. J. DiSalvo, “Thermoelectric cooling and power generation”, Science,
Vol. 285(5428), p. 703, 1999.
【4】 柯文賢，「熱電轉換及其應用」，科技發展政策報導，第5期，51-65，
2007。
【5】 https://www.itri.org.tw/chi/news/detail.asp?RootNodeId=060&NodeId=
061&NewsID=673.
【6】 A. D. LaLonde, Y. Pei, H. Wang, G. J. Snyder, “Lead telluride alloy thermoelectrics”, Materials Today, Vol. 14(11), pp. 526-536, 2011.
【7】 http://www.physics.arizona.edu/~pjacquod/Site/Thermoelectricity_files/bmw.pdf.
【8】 莊東漢、葉威廷、黃振東、謝慧霖，「熱電模組接合技術及其挑戰」，工業材料雜誌，第322期，072-079，2013。
【9】 T. M. Ritzer, P. G. Lau, A. D. Bogard, “A critical evaluation of today's thermoelectric modules”, International Conference on Thermoelectrics, pp. 619-623, 1997.
【10】 K. T. Wojciechowski, M. Schmidt, R. Zybala, J. Merkisz, P. Fuć, P. Lijewski, “Comparison of waste heat recovery from the exhaust of a spark ignition and a diesel engine”, Journal of Electronic Materials, Vol. 39, pp. 2034-2038, 2010.

【11】 T. Kacsich, E. Kolawa, J.P. Fleurial, T. Caillat, M.A. Nicolet,“Films of Ni-7 at% V, Pd, Pt and Ta-Si-N as diffusion barriers for copper on Bi2Te3”, Journal of Physics D: Applied Physics, Vol. 31(19), pp. 2406-2411, 1998.
【12】 林哲緯，“Bi2Te2.55Se0.45熱電材料與Cu/Ag電極之薄膜固液擴散接合研究“，國立台灣大學，碩士學位論文，2011。
【13】 L. D. Hicks, T. C. Harman, X. Sun, M. S. Dresselhaus, “Experimental study of the effect of quantum-well structures on the thermoelectric figure of merit”, Physical Review B, Vol. 53(16), pp. 493-496, 1996.
【14】 H. Beyer, J. Nurnus, H. Böttner, A. Lambrecht, T. Roch, G. Bauer, “PbTe based superlattice structures with high thermoelectric efficiency”, Applied Physics Letters, Vol. 80(7), pp. 1216-1218, 2002.
【15】 Y. Pei , J. L. Falk , E. S. Toberer, D. L. Medlin , G. J. Snyder,“High thermoelectric performance in PbTe due to Large nanoscale Ag2Te precipitates and La-doping“, Advanced functional materials, Vol. 21, pp. 241-249, 2011.
【16】 J P. Heremans, V. Jovovic, E. S. Toberer, A. Saramat, K. Kurosaki, A. Charoenphakdee, S. Yamanaka, G. J. Snyder, “Enhancement of thermoelectric efficiency in PbTe by distortion of the electronic density of states“, Science, Vol. 321, p. 554, 2008.
【17】 G. Xu, Y. Gao, C. Ge, W. Shen, “Thermoelectric properties of p-type (Bi0.15Sb0.85)2Te3 -PbTe graded thermoelectric materials with different barriers“, Journal of University of Science and Technology Beijing, Vol. 12(4), pp. 347-350, 2005.

【18】 K. Qiu, A.C.S. Hayden, “Development of a thermoelectric self-powered residential heating system”, Journal of Power Sources, Vol. 180, pp. 884-889, 2008.
【19】 朱旭山、徐振庭，「薄型熱電元件在環境環境能源擷取之應用與發展方向」，工業材料雜誌，第322期，087-093，2013。
【20】 吳奕諼，“碲化鉍合金熱電薄膜發電器之設計與製造”，國立臺灣科技大學，碩士學位論文，2009。
【21】 A. Schmitz, C. Stiewe, E. Müller, “Preparation of ring-shaped thermoelectriclegs from PbTe powders for tubular thermoelectric modules”, Journal of Electronic Materials, Vol. 42(7), pp. 1702-1706, 2013.
【22】 M. Kubo, T. Itoh, K. Tokuda, J. Shan, K. Kitagawa, “Fabrication of layered p-type AgSbTe2-(Bi,Sb)2Te3 thermoelectric module and its performances”, International Conference on Thermoelectrics, pp. 429-432, 2003.
【23】 O. Yamashita, H. Odahara, S. Tomiyoshi, “Effect of metal electrode on thermoelectric power in bismuth telluride compounds”, Journal of Materials Science, Vol. 39, pp. 5653-5658, 2004.
【24】 J. Fan, L. Chen, S. Bai, X. Shi, “Joining of Mo to CoSb3 by spark plasma sintering by inserting a Ti interlayer”, Materials Letters, Vol. 58, pp. 3876–3878, 2004.
【25】 D. Zhao, X. Li, L. He, W. Jiang, L. Chen, “High temperature reliability evaluation of CoSb3 electrode thermoelectric joints”, Intermetallics, Vol. 17, pp. 136-141, 2009.

【26】 C. Long, Y. Yan, J. Zhang, B. Ren, Z. Wang, “New integration technology for PbTe element”, International Conference on Thermoelectrics, pp. 386-391, 2006.
【27】 A. Singh, S. Bhattacharya, C. Thinaharan, D. K. Aswa, S. K. Gupta, J. V. Yakhmi, K. Bhanumurthy, “Development of low resistance electrical contacts for thermoelectric devices based on n-type PbTe and p-type TAGS-85((AgSbTe2)0.15(GeTe)0.85)”, Journal of Physics D: Applied Physics, Vol. 42(1), pp. 1-6, 2009.
【28】 S. Nakamura, Y. Mori, K. Takarabe, “Analysis of the microstructure of Mg2Si thermoelectric devices”, Journal of Electronic Materials, 2014.
【29】 K. Hasezaki, H. Tsukuda, A. Yamadal, S. Nakajimaz, Y. Kang, M. Niino, “Thermoelectric semiconductor and electrode-fabrication and evaluation of SiGe/electrode”, International Conference on Thermoelectrics, pp. 599-602, 1997.
【30】 K. Hasezaki, H. Tsukuda, A. Yamada, S. Nakajima, Y. Kang, M. Niino, “SiGe/electrode response to long-term high-temperature exposure”, International Conference on Thermoelectrics, pp. 460-463, 1998.
【31】 H. Ono, T. Nakano, T. Ohta, “Diffusion barrier effects of transition metals for Cu/M/Si multilayers (M=Cr, Ti, Nb, Mo, Ta, W)”, Applied Physics Letters, Vol. 64(12), pp. 1511-1513, 1994.
【32】 G. Xu, Y. Gao, C. Ge, W. Shen, “Thermoelectric properties of p-type (Bi0.15Sb0.85)2Te3-PbTe graded thermoelectric materials with different barriers”, Journal of University of Science and Technology Beijing, Vol. 12(4), pp. 347-350, 2005.

【33】 Y.C. Lan, D.Z. Wang, G. Chen, Z.F. Ren, “Diffusion of nickel and tin in p -type (Bi,Sb)2Te3 and n -type Bi2(Te,Se)3 thermoelectric materials”, Applied Physics Letters, Vol. 92, pp. 1-3, 2008.
【34】 M. Orihashi, Y. Noda, L. Chen, Y.S. Kang, A. Moro, T. Hirai, “Electric properties of Ni/n-PbTe and Ni/p-Pb0.5Sn0.5Te joined by plasma activated sintering”, International Conference on Thermoelectrics, pp. 543-546, 1998.
【35】 H. Xia, F. Drymiotis, C.L. Chen, A. Wu, G.J. Snyder, “Bonding and interfacial reaction between Ni foil and n-type PbTe thermoelectric materials for thermoelectric module applications”, Journal of Materials Science, Vol. 49, pp. 1716-1723, 2014.
【36】 吳騌豪，“碲化鉛/奈米銀複合粉體之製備及其火花電漿燒結體之熱電性質研究”，國立成功大學，碩士學位論文，2009。
【37】 Y. Gelbstein, G. Gotesman, Y. Lishzinker, Z. Dashevsky , M.P. Dariel, “Mechanical properties of PbTe-based thermoelectric semiconductors”, Scripta Materialia, Vol. 58, pp. 251-254, 2008.
【38】 李昂倖，“碲化鉛熱電材料與銅電極之填料接合性質研究”，國立臺灣師範大學，碩士學位論文，2012。
【39】 A. J. Strauss, “Effect of Pb- and Te- saturation on carrier concentrations in impurity-doped PbTe”, Journal of Electronic Materials, Vol. 2(4), pp. 553-569, 1973.
【40】 Y. Pei, A. F. May, G. J. Snyder, “Self-tuning the carrier concentration of PbTe/Ag2Te composites with excess Ag for high thermoelectric performance”, Advanced Energy Materials, Vol. 1, pp. 291-296, 2011.

【41】 C.P. Cheng, Y.S.Ke, M.J. Dai, C.K. Liu, L.L.Liao, C.H Cheng, “High-temperature failure analysis of thermoelectric PbTe module using Al-Si bonding”, International Conference on Thermoelectrics, 2013.
【42】 T.B. Massalski, H.Okamoto, Binary alloy phase diagrams, ASM International, 1990.
【43】 S. Bader, W. Gust, H. Hieber, “Rapid formation of intermetallic compounds interdiffusion in the Cu-Sn and Ni-Sn systems”, Acta Metallurgica et Materialia, Vol. 43(1), pp. 329-337, 1995.
【44】 T. Laurila, V. Vuorinen, J.K. Kivilahti, “Interfacial reactions between lead-free solders and common base materials”, Materials Science and Engineering: R: Reports, Vol.49(1-2), pp. 1-60, 2005.
【45】 J.P. Coughlin, J.J. Williams, G.A. Crawford, N. Chawla, “Interfacial reactions in model NiTi shape memory alloy fiber-reinforced Sn matrix ‘‘Smart’’ composites”, Metallurgical and Materials Transactions A, Vol. 40A, pp. 176-184, 2009.
【46】 D. C. Yeh , H. B. HunSngton, “Extreme fast-diffusion system : nickel in single-crystal Sn” , Phys. Rev. Lett., Vol.53(15), pp. 1469-1472, 1984.
【47】 H.S. Dow, M.W. Oh, B.S. Kim, S.D. Park, B.K. Min, H.W. Lee, D.M. Wee, “Effect of Ag or Sb addition on the thermoelectric properties of PbTe”, Journal of Applied Physics, Vol. 108, pp. 1-7, 2010.
【48】 J. Andrieux, O. Dezellus, F. Bosselet, M. S. Peronnet, C. Sigala, R. Chiriac, J.C. Viala,“Details on the formation of Ti2Cu3 in the Ag-Cu-Ti system in the temperature range 790 to 860℃”, Journal of Phase Equilibria and Diffusion, Vol. 29, pp. 156-162, 2008.
【49】 W.P. Lin, D.E. Wesolowski, C.C. Lee,“Barrier/bonding layers on bismuth telluride (Bi2Te3) for high temperature thermoelectric modules”, Journal of Materials Science: Materials in Electronics, Vol. 22, pp. 1313-1320, 2011.