本論文係研究以Polyimide(PI)為基板，製作串聯64個熱電偶的熱電堆。利用溼式蝕刻方式蝕刻厚度為25μm的PI，使熱電偶冷熱端分別在上下方的三維結構，製作成串聯64個Cu-Ni熱電偶，可應用於非平坦表面之溫度感測器。
最佳蝕刻PI條件由不同的KOH及C2H7NO濃度在某一蝕刻溫度決定。為了找出較佳的蝕刻速率，本實驗改變KOH及C2H7NO的濃度，將蝕刻溫度控制在80oC。由量測結果得知，KOH濃度在7M~9M，C2H7NO濃度在2M~4M有較快的蝕刻速率。
為了降低PI經濕蝕刻後的表面粗糙，先旋塗一層約1μm的光阻再沈積Cu與Ni，完成串聯64個熱電偶於PI上。在靈敏度量測方面，以hotplat供應熱電堆熱端之熱源，並使用電子溫度計偵測熱電堆冷熱端的溫度，由溫差與輸出電壓的關係，得到元件之靈敏度為0.4412mV/oC。
最後，本實驗將自製熱電堆貼在筆記型電腦、燒杯以及檯燈的表面，經由量測得到的電壓推算出表面溫度。由實驗結果得知，自製熱電堆所推算的溫度與電子溫度計量測溫度近似，因此，成功地在非平坦的表面做為溫度感測器應用。

This paper is to fabricate a three-dimensional(3D) thermopile with 64 in-series thermocouple coated on polyimide(PI) substrate. By using wet-etching technology to etch through PI with thickness 25μm, the cold and hot junction of thermocouple are then located at the surface and bottom of PI. The device is made with 64 Cu-Ni thermocouples connected in series and can be used as thermal sensor on curved-surfaced.
The optimal etching PI condition can be determined from various degree of the mixture of KOH and C2H7NO. In order to find larger etching rate, we vary KOH and C2H7NO concertration and the etching temperature is controlled at eighty degrees. From the results of the experiment, etchant is composed of 7M~9M KOH and 2M~4M C2H7NO has larger etching rate.
In order to reduce PI surface roughness after etching, we spin ~1μm photoresist(PR) on above etched surface, then deposit Cu and Ni to accomplish 64 thermocouples on PR. For sensitivity measurement, by using hotplat to supply heat for thermopile and using digital thermometer to measure the truth temperature of hot and cold junction, we record the relationship between truth temperature difference and output voltage. The sensitivity of 3D thermopile is 0.4412mV/oC.
Finally, the 3D thermopile was pasted on the surface of the notebook, beaker, and desk lamp, we measure output voltage and determine temperature. From our data, the measured temperature of 3D thermopile is closing to that of digital thermometer. Therefore, we succeed to fabricate 3D thermopile and use it as thermal sensor on curved surface.

[1] Fukang Jiang, Gwo-Bin Lee, Yu-Chong Tai, and Chin-Ming Ho, “A flexible micromachine-based shear-stress sensor array and its application to separation-point detection,” Sensors and Actuators A/Physical, Vol.79, pp.194-203, 2000.
[2] Vladimir J. Lumelsky, Michael S. Shur, and Sigurd Wagner, “Sensitive Skin,” IEEE Sensors Journal, Vol.1, No.1, June 2001.
[3] E. Castano, E. Revuelto, M.C. Martin, A. Garcia-Alonso, F.J. Gracia, “Metallic thin-film thermocouple for thermoelectric microgenerators,” Sensors and Actuators A/Physical, Vol.60, pp.65-67, 1997.
[4] Q Chen, J P Longtin, S Tankiewicz, S Sampath and R J Gambino, “Ultrafast laser micromachining and patterning of thermal spray multilayers for thermopile fabrication,” Journal of Micromechanics and Microengineering, Vol.14, pp.506-513, 2004.
[5] Wenmin Qu, Matthias Plotner and Wolf-Joachim Fischer, “Microfabrication of thermoelectric generators on flexible foil substrates as a power source for autonomous Microsystems,” Journal of Micromechanics and Microengineering, Vol.11, pp.146-152, 2001.
[6] Koichi Itoigawa, Hiroshi Ueno, Masayoshi Shiozaki, Toshiyuki Toriyama and Susumu Sugiyama, “Fabrication of flexible thermopile generator,” Journal of Micromechanics and Microengineering, Vol15, pp.233-238, 2005.
[7] S. Hasebe, J. Ogawa, T. Toriyama, S. Sugiyama, H. Ueno and K. Itaigawa, “Design and Fabrication of flexible thermopile for power generation,” International symposium on micromechatronics and human science, 2003.
[8] D.M. Rowe, Ph.D., D.Sc. CRC Handbook of THERMOELECTRICS.
[9] Safa Kasap, Thermoelectric Effects In Metal: Thermocouple.
[10] Weckmann, Stephance, “Dynamic electrothermal model of a sputtered thermopile thermal radiation detector for earth radiation budget applications” 1997.
[11] S.C. Allison, R.L. Smith, D.W. Howard, C. Gonzalez, S.D. Collins, “A bulk micromachined silicon thermopile with high sensitivity,” Sensors and Actuators A/Physical, Vol.104, pp.32-39, 2003.
[12] 林直慶, ”Design and Fabrication of Thermoelectric Coolers Using MEMS Technology,” 國立清華大學碩士論文, 2002.
[13] 田宏隆, 工業材料, 165(6), 2004.
[14] Ji-song Han, Zhi-yong Tan, K Sato and M Shikida,“Three-dimensional interconnect technology on a flexible polyimide film,” Journal of Micromechanics and Microengineering, Vol4, pp.38-48, 2004.
[15] http://www2.dupont.com/DuPont_Home/en_US/
[16] http://www.ube-ind.co.jp
[17] 林振華、林振富, “高密度軟性電路板,” 1990.
[18] G. Xue, “Studies of Etching Mechanism of Polyimide Films on Silicon Chips,” Die Angewandte Makromolekulare Chemie, Vol.142, pp.61-68, 1986.
[19] Ji-song Han, Zhi-yong Tan, K Sato and M Shikida, “Thermal-type micro sensor array on PI film substrate having wet-etched through-holes for interconnection,” 12th International Conference on Solid State Sensor, Actuators and Microsystems, 2003.
[20] James D. Plummer, Michael D. Deal, Peter B. Griffin, “Silicon Vlsi Technology- Fundamentals, Practice and Modeling” Pearson Education International,2000.