應用在微光機電之離子性聚合物--金屬複合材料之表面處理

Abstract

高分子薄膜Nafion 具備重量輕、尺寸薄、可撓曲以及耐酸鹼之特色，再加上與金屬複合後之材料同時擁有特殊的電性與機械性質。因此，離子性聚合物--金屬複合材料是近年來受到矚目重要軟性光電材料之一，並且有希望繼半導體和平面顯示技術之後，成為下一個新興產業。然而，傳統上離子性聚合物--金屬複合材料大多應用於微機電制動元件以及機械手臂，因此目前學界對於使用高分子為基底的離子性聚合物--金屬複合材料作為微機電光學元件的光學性質與機械性質之間相關的完整關聯性仍尚未建立完整的理論。於此，離子性聚合物--金屬複合材料要實現在光機電的應用上還有一些困難需要克服，例如高品質的表面優化處理、低光衰減性、適當的應力應變、元件制動時其工作電壓與電阻之間的調控等等。 本論文中，我們選擇了一個高分子薄膜Nafion (N117)來製造此離子性聚合物--金屬複合材料，整個低溫製程(< 55℃)不會破壞高分子薄膜基底。我們成功控制無電鍍製程中不同的環境參數，在Nafion表面沉積出高導電性的金屬電極。對微機電製程技術應用於光學系統而言，須選擇紅外光至可見光波段皆有良好反射率的金屬作為表面電極。然而傳統鉑製程過於耗時且昂貴，常見的鋁又由於其高電阻值( )特性使得訊號傳輸時間較長。而銅導電性極佳( )，因此銅製程之出現將提供未來微光機電技術一個新的方向。 實驗結果顯示，使用離子液體做為電解液可有效延長元件使用壽命，進而應用在通訊元件，例如：天線之製備；而第一代鉑製程與第二代銅製程其不同的參數設計可以獲得具有不同光學與機械性質的金屬電極，並且第二代製程有效縮短無電鍍時間來確保金屬電極表面的粗糙度不被過度放大以及獲得有效的表面平整度(Rq ~ 60 nm)，成功製作出更平滑之高反射性表面。因此，藉由控制無電鍍與電鍍製程中的各項參數，可以調整離子性聚合物--金屬複合材料表面的機械性質、表面平整度、光衰減、結晶形貌以及組成元素。

Traditionally, the flexible thin-film device, IPMC, can only be used as an actuator due to its rough metal surface. Our goal is to provide an electro-chemistry optical actuator with smooth mirror surface and a voltage-controlled flexible polymer substrate for reconfigurable antenna. These are new application in aspect of optical system for free from surfaces and communication device designs just like antenna on micro-electro-mechanical systems (MEMS). When traditional Pt-IPMC is approaching to its optical and mechanical limits, introduction of performance boosters by alternative materials or novel surface treatments has become necessary. With high reflectance, low resistance and low-cost, Cu has become a very promising candidate to be used in MEOMES. In this thesis, by a low-temperature process, including adhesion metal electrode bonding and surface treatments, high-quality Cu electrodes were successfully integrated onto flexible N117 substrates by effective electroless deposition process. It was found that the insertion loss (I.L.) of Cu electrodes with N117 substrates was dramatically decreased for the 1550nm incidence infrared. Additionally, the optical characters of surface roughness (Rq) for thin IPMC film would be characterized by optical white-light interferometer to produce high quality two-dimensional surface maps of the IPMC. Moreover, the voltage-controlled flexible polymer substrate for reconfigurable antenna is also an important issue. In this thesis, the actuation resistance and working voltage of the Pt-IPMC antenna with EMI-Tf electrolyte are characterized. Finally, we apply the 1st generation Pt-IPMCs and the 2nd generation Cu-IPMCs on strain response test for mechanical properties measurements. The Young’s modulus of the 2nd generation Cu-IPMC is less than the 1st generation Pt-IPMC, and proper surface treatments also further boost the reflectance enhancement. In addition, N117 substrates exhibit flexible characteristics and provide tremendous chemical stability. These results suggest that the IPMC could be promising for inexpensive MEMS devices and applicable on other large area nanostructure-based optoelectronics devices for MOEMS.