一種同軸線上滾印技術於微奈米陣列銀線之滾印研究

Abstract

具可彎曲、高導電率及高透光率的微奈米級銀導線適用於光電產業及客戶導向的電子產品場合。本研究提出一種「同軸線上滾印技術」應用於透明PET膜上，製造微奈米級超高細長比銀線陣列電路。同軸線上滾印系統採「軸對稱式低重心設計」，並將切削與滾印兩主要機構設計於同一系統，可使微滾齒陣列模具切削與微奈米銀線陣列滾印都在相同的座標系統及相同的軸心上作業，意謂最高同心精度的微滾齒陣列具最小的偏擺量，故可得最細且規律平行或規律彎曲的銀導線陣列。為提供微量且定量的銀漿供給，銀漿供給機構採精密微細螺紋設計，銀漿能不斷地精準輸入梳狀微流道陣列，塗佈於微滾齒陣列模具上，確保長距離滾印不會斷漿。藉由控制切削技術以改變微滾齒模具的表面粗糙度，可創造出銀漿在模具上的接觸角大於銀漿在PET膜上的接觸角，使銀漿容易脫模轉印至PET膜上。為獲得最細銀線寬度，導入雙變數的刮板擺設函數、最適刃地寬度、最小刃地間隙與無縫滾齒滾軸等設計。實驗結果發現，在同軸滾印模式下，微滾齒刃地在5 µm的寬度、1 µm的間隙及Ra6 nm的表面粗糙度條件，銀漿液滴的內聚力與附著力能獲得平衡，具有最窄及最佳的匯聚能力，可得最細的銀線寬度。驗證的微奈米銀線(寬5 µm，厚1 µm)具超高細長比、規律、高筆直度與高一致性，並能切確地驅動LED裝置，顯示同軸滾印技術具高精度及高可控制性。此外亦提出穩態簡諧伺服運動切削，以原位斜進精切削製作波浪狀微滾齒陣列刃地，滾印長100 mm, 寬35 µm之波浪型微奈米銀導線。直線與波浪型微奈米銀導線之導電膜均具高導電率(σ=1.94x106 S/m, σ=1.77x106 S/m)及高透光率(T=90.5 %, T=89.9 %)，均優於商用ITO導電膜(導電率σ=9.26×105 S/m, 透光率T=78.3 %)，達到透明導電薄膜基板的電路佈線取代ITO導電薄膜之目的。A ‘co-shaft in-situ rolling-imprinting technique’ is proposed to make silver micro-nanowire array with an ultra-high slenderness ratio on transparent Poly-Ethylene-Terephthalate (PET) film in this study. The two major mechanisms for the microrolling-tooth array mold cutting and the silver micro-nanowire array rolling-imprinting are designed in the rolling-imprinting system so that the mold cutting and micro-nanowire rolling-imprinting can be conducted in the same coordinate system and the same center of rolling shaft. This means that the microrolling-tooth array with the highest concentric accuracy has the smallest swaying errors, creating the thinnest and regularly parallel or regularly curved silver wire array. To provide a steady, micro-amount and quantitative silver-paste supply, the designed silver-paste supply mechanism comprises the paste to comb-shaped microchannel array by fine screw thread. Changing the surface roughness in which makes the contact angle of the silver-paste on the roller mold to be larger than that of on the PET film facilitates to transfer the mold releasing of the silver-paste to the PET film. A doctor-blade placement function design with double variables including the optimal letterpress-width and the minimal letterpress-gap is conducive to excess silver-paste scraped off to minimize the wire-width in the experiment. Experimental results found that the silver-paste molecules have the optimal congregation effect and creating thus the minimalwire-width when using the 5-µm letterpress-width, 1-µm letterpress-gap, and Ra 6-nm surface roughness on the roller mold. The argument proves the silver-paste’s innate ‘internal force balance characteristic’ in this study. The resultant silver micro-nanowire array with 5 µm width, 1 µm thickness and an ultra-high slenderness ratio, high-straightness, -consistency and -regularity has been achieved and reliably drive the LED device. In addition, a steady-state simple harmonic servo motion cutting and in-situ oblique fine cutting technology are also proposed in this study, used to make a wave-shaped microrolling-tooth array mold, to roll-printing a serpentine curve micro-nano silver wire with 100 mm length and 35 μm width. The conductive films with straight and serpentine curve micro-nano silver wires have high conductivity (σ=1.94x106 S/m and 1.77x106 S/m) and high transmittance (T=90.5% and T=89.9%) , are both superior to the commercial ITO conductive film (conductivity σ=9.26×105 S/m, transmittance T=78.3 %), and achieve the purpose of replacing the ITO conductive film with the circuit routing of the transparent conductive film.