精密網版印刷應用於微熱電致冷器之研製

Abstract

人類對於產品高頻化、高速化、高功率、低面積、高密度的追求越趨提升，以致高性能電子元件所產生的高熱量，將會嚴重影響到電子元件的特性及運作，如何將電子元件所產生升的高熱量以最快的速度排出，對於系統設計以及製程設計整合工程師而言，將是一項亟待突破的課題。應用網版印刷技術製作高性能微型熱電致元件，除了可以降低生產成本與時間之外，亦能簡化製程有利元件的普及化，如此便能提供高整合、高效能更優質的散熱能力。 本研究主要分為三大項目：(1) 添加不同金屬材料粉末，在不影響網版的透孔率情況下，改變n-type與p-type熱電漿料的混合比例，對印刷成形之熱電材料膜的特性進行探討；(2) 以網版印刷技術印製熱電材料膜於矽基板上，對其席貝克係數、電阻率與熱傳導值進行特性評估；(3) 應用網版印刷技術，透過雙矽晶圓的方式，採用覆晶粒接合技術進行熱電元件製程的初步測試。實驗結果顯示，於n-type材料Bi2Te3中，若添加了不同比例的Sn，除了能得到較緻密的表面形貌之外，亦能轉變為p-type材料。若在Bi2Te3熱電漿料中添加10 wt.%的Sn，其席貝克係數、電阻率與熱傳導值分別為54.17 uV/K、1.99*10-5 Ohm-m和0.45 W/m-K。在p-type材料Sb2Te3中，添加5 wt.%的Sn，則其席貝克係數、電阻率與熱傳導值分別為98.13 uV/K、2.27*10-5 Ohm-m和0.32 W/m-K，在環境溫度為300 K下，熱電優質可達0.39。由於熱電漿料中添加了金屬Sn粉末，故可將燒結溫度降低至231 deg-C以下，有利於日後以網版印刷的製程方式，製作在聚亞醯胺高分子可撓性基板上，將可大幅提高熱電致冷元件的應用方向。日後若能提高網版印刷製程的品質，那麼便有機會以更快速且低成本的製備技術，達到熱電致冷晶片的普及化與提升市場上之應用。Most of today's electronic products draw high frequency, high speed, high power, low area, and high density, which have overheating problems for system designers and engineers. The volume of traditional thermoelectric cooler chips is too big to be integrated with micro-device, and the fabrication processes are complicated and high cost. Screen-printing technique can fabricate thick-film structure of micro-thermoelectric cooler, which are mass production, simple process and low cost technique. It can gain a high quality of heat removal ability by screen-printing technique. This research has three points as followed: (1) Percent of different materials content with thermoelectric paste. (2) Using screen-printing technology to fabricate thermoelectric film on silicon substrate, and to measure Seebeck coefficient, electric conductivity, and thermal conductivity. (3) Using screen-printing technology to experiment and discuss process of thermoelectric component fabricated by two-wafer method. In this research, thermoelectric density of thick film can be improved, and transform material property of Bi2Te3 from n-type to p-type by adding Sn element. The Seebeck coefficient , electrical resistivity and thermal conductivity are 54.17 uV/K, 1.99*10-5 Ohm-m and 0.45 W/m-K of Bi2Te3 adding with 10 wt.% Sn. The Seebeck coefficient , electrical resistivity and thermal conductivity are 98.13 uV/K, 2.27*10-5 Ohm-m and 0.32 W/m-K of p-type Sb2Te3 adding with 10 wt.% Sn, and the maximum ZT value of 0.39 at 300 K. Adding Sn powder can decrease the sintering temperature under 231 deg-C, and this is helpful to print thermoelectric material on flexible substrate (polyimide). In the future, micro thermoelectric cooler with swift, low-cost, and can popularized application can be fabricated by improving the screen printing process quality.