以SU-8厚膜光阻紫外光深刻微電鑄軟磁性鎳鐵微構件及其電化學特性和成份梯度之研究

Abstract

在本研究中，以紫外光深刻SU-8厚膜光阻製造深寬比約12之電鑄凹模。利用硫酸基鎳鐵鍍液對SU-8圖案進行電鑄，此電鑄鎳鐵微構件高度可達200 mm、深寬比達12。 利用旋轉環-圓盤電極(RRDE)結合C-V Test 研究鎳鐵合金的電化學特性。本實驗收集效率為0.4615。在實驗中鎳鐵不規則共沉積主要是受電極表面Ni(OH)+和Fe(OH)+濃度的影響。鎳沉積被較高表面濃度的Fe(OH)+所抑制，但在高pH值下，表面Fe(OH)+濃度卻無明顯的優勢。在添加劑方面，糖精比檸檬酸更能有效地降低析氫反應。 在鎳鐵微構件的成份梯度研究上，擴散-控制行為導致在較狹窄的凹膜中鐵沉積被抑制而降低鐵含量；在較寬的凹膜中則受對流行為控制。在大於1ASD的電鍍條件下，成份梯度結果顯示質傳效應使得擴散-控制行為更為明顯。在鎳鐵共沉積中，晶粒細緻效應使得晶粒隨著鐵含量升高而細化。當鐵含量達到41 wt.%，晶粒細化至12.18 nm。當晶粒細化至15 nm以下，逆Hall-Petch效應使得硬度呈現下降趨勢。在磁性量測上，保磁力為0.5Oe以下，而飽和感應則約為2500Gauss。

UV-LIGA is one of MEMS to fabricate three-dimension microstructure of high aspect ratios. UV-exposure SU-8 pattern of high aspect ratio ~12 used to the electroplated mold was demonstrated. A sulphate-based Ni-Fe electrolyte was developed for electroplating through Su-8 pattern to form high aspect microstructure. Microstructure with a maximum height of 200 mm and aspect ratios of one to 12 were filled completely. A rotating ring-disk electrode (RRDE), combined with stripping voltammetry has been applied to a convenient, fast and inexpensive technique of electrochemical characterization of Ni-Fe alloy plating system. Experimental collection efficiency was determined about 0.4615 precisely. Ni-Fe codeposition depended on the formation of Ni(OH)+ and Fe(OH)+ on electrode surface. Ni deposition was suppressed in the presence of higher surface concentration of Fe(OH)+; However, surface concentration of Fe(OH)+ did not take advantage in high pH. Additive, sacchrain decreasing H2 evolution was more usable than citrate while Ni-Fe plating through pattern. Studied on composition distribution over the height of Ni-Fe showed that diffusion-limiting controlled lead a suppression of Fe deposition to decrease the iron content in narrow pattern and convection-controlled occurred in wild pattern. Composition gradient varied with current density also showed mass transport under a current density of about 1 ASD no significant enhancement. Codeposition iron had profound grain refining effect which increasing the iron content up to 41 wt.%, the grain size decreased to 12.18 nm. With decreasing grain size to 15 nm, the hardness of electroplating Ni-Fe alloy started following an inverse Hall-Petch behavior was observed leading to softening at the smallest gain sizes. The coercitivity was determined to be less than 0.5 Oe and the saturation magnetization was about 2500 Gauss.