精密網版印刷應用於熱電材料膜之成形技術開發

Abstract

現代科技日新月異，電子元件在有限空間中以最密集、最有效率的方式排列，且在效能導向之下，元件的工作頻率提升，溫度也隨之升高，因此冷卻成為不可忽視的課題。微熱電致冷元件具有體積小、無污染、控溫精確等優點，符合目前產業趨勢。然而，目前熱電致冷元件製作方式，皆以傳統技術如布里茲曼法、熱壓成形法，或微加工技術如濺鍍/蒸鍍法、MOCVD法等為主。若應用網版印刷技術製作熱電致冷元件，將可以簡化上述製作法的繁雜程序，也減少製造成本與時間，有利於產業應用之普及化。 本研究主要分為三大項目：(1) 針對網版印刷技術之成型結構的解析度與品質加以測試評估；(2) 以網版印刷技術印製熱電材料膜於矽基板上，對其熱電性質與表面形貌、成分等進行特性評估；(3) 應用網版印刷技術，進行熱電元件製程的初步測試與探討。實驗結果顯示，本實驗以網版印刷技術，使用黏度為50 Pas的UV感光型GN-52-479油墨，進行最佳線寬範圍之印刷測試，圖案最小線寬可達40 m，而線寬50至100 m以上有最佳的印刷品質呈現。此外，將黏結劑與熱電材料粉末，以20 wt.%與80 wt.%比例混合調配成熱電漿料，並印製成18 mm  18 mm面積的熱電膜，Bi2Te3與Sb2Te3分別以560 C與585 C，在氫與氬的混合氣氛下，進行四小時燒結，可於燒結過程中還原氧化的熱電膜。燒結後可分別測得席貝克係數與電阻值，Bi2Te3為-57.06 V/K與4.4010-5 m，而Sb2Te3為64.70 V/K與7.3310-5 m。網印技術應用於熱電元件製程進行初步測試，重複三次熱電結構之堆疊印刷程序，可使75與100 m線寬的堆疊結構，達到20 m以上的厚度。未來將繼續熱電元件後續製程之測試與評估，期望不久的將來實現低成本與方便量產為訴求的熱電元件製造技術。In nowadays, electronic components are tended to have high density and high work-frequency, and property of high temperature appears. Therefore, cooling of components is an important consideration. Micro-thermoelectric cooler is suit to application of industry and has advantages as followed: small volume, no pollution, and exact temperature control etc. At present, thermoelectric cooler are fabricated by complicated traditional technologies such as Bridgman method, hot pressing method, or micro fabrication such as sputter, hot evaporation, or MOCVD (metal-organic chemical vapor deposition). Screen-printing technology can fabricate micro thermoelectric components with simple process, lower cost and less fabrication hours, and can be popularized in industry. This research has three points as followed: (1) Estimation of DPI (dots per inch) and quality of structure formation by screen-printing technology. (2) To fabricate thermoelectric film on silicon substrate by screen-printing technology, and to estimate morphology, composition, and thermoelectric characteristic. (3) To experiment and discuss process of thermoelectric component fabricated by screen-printing technology. In the research, we use UV sensitive ink (GN-52-479) with viscosity of 50 Pas to test the best range of width. The results show that the smallest width of pattern is 40 m, and pattern with 50-100 m width has better screen-printing quality. Besides, we mix 1:4 by weight of binder and thermoelectric powder to be thermoelectric ink and print 18×18 mm2 thermoelectric film. After 4 hours sintering of Bi2Te3 (560 ºC) and Sb2Te3 (585 ºC), Seeback coefficient and resistivity of Bi2Te3 are -57.06 V/K and 4.40×10-5 m, and values of Sb2Te3 are 64.70 V/K and 7.33×10-5 m. Using the technology to print thermoelectric structure three times can get thickness more than 20 m with widths of 75 m and 100 m.