石墨鍍銀/奈米銀複合導電膠製備與導電特性之研究

Abstract

本實驗共分成四大部分：第一部分為製備聚苯胺的研究；第二部分為製備導電粒子的研究；第三部份為製備導電膠的研究；第四部份則對導電顆粒組成進行改良，加入平均粒徑為100nm的奈米銀，發現導電度有明顯的提升。首先藉由UV-Vis以及GPC儀器測量聚苯胺的特徵峰與分子量；接著藉由粒徑分析儀與SEM觀察GS-75石墨顆粒尺寸與形貌；再經由XRD及ICP儀器觀察無電鍍銀後，銀是否有鍍著在微粒表面與銀鍍上去的量。最後則為製備導電膠以及改變導電顆粒組成對導電度影響的研究。 實驗結果發現在製備聚苯胺實驗方面，0˚C下化學合成的聚苯胺由GPC測量其平均分子量為3756；由UV-vis儀觀察去摻雜態聚苯胺，其UV-vis光譜波長在320nm及640nm左右有吸收，分別是由苯環的π-π*吸收及醌環的exciton吸收所造成的。製備得到的去摻雜態聚苯胺用不同的摻雜酸(HCl、HBr、HNO3、H3PO4、DBSA、CH3COOH、HOCH2COOH)摻雜，以DMSO做為溶劑，能得知硝酸摻雜態聚苯胺溶液擁有較高導電度，其值為231.4μs/cm；而以DBSA為摻雜酸的摻雜態聚苯胺在DMSO溶劑中有最大的溶解度6.25mg/ml。 製備導電粒子實驗方面先將平均粒徑為0.982 μm的扁平雪片狀石墨粉GS-75無電鍍銀，將無電鍍銀的程序分成兩組，一組有敏化活化，另一組不經敏化活化步驟；接著再由XRD觀察無電鍍銀後的微粒可知無論有敏化活化與否在鍍銀石墨粉GS-75/Ag表面皆產生Ag與幫助電性導通的Ag2O。由ICP觀察石墨粉無電鍍銀鍍上的量，可發現經敏化活化步驟的GS-75/Ag表面吸附銀的量明顯較未敏化活化步驟來的多。 在製備導電膠實驗方面發現石墨微粒經過無電鍍銀，且加入聚苯胺溶液和硫醇當分散劑之後，電阻係數ρ會下降，故GS-75在鍍銀且加入聚苯胺溶液後最低之電阻係數可達3 x 10-4ohm-cm。固化溫度在200°C之後，電阻係數便趨於穩定不再下降。接著我們再將部份GS75/Ag微米級導電粒子置換為平均粒徑為100nm的奈米銀，研究結果指出在GS75/Ag：Ag nanopowder 重量百分比為 8 ：2時， 其電阻係數ρ測得為7.7 x 10-5ohm-cm，此值為本研究最佳結果。

The thesis was divided into four parts. The first part of study was preparing polyaniline. The second part of study was preparing conductive particles. The third part of study was preparing electrically conductive adhesives (ECAs). The fourth part was alternating some silver-plated conductive particles to Ag nanopowders which the average radius is 100nm. In the experiments, polyaniline was characterized by ultraviolet-visible spectroscopy and the molecular weight of polyaniline was measured by GPC. The particle size and surface morphology were developed by particle size instrument and SEM. We also analyzed whether silver was electroless plated on particles surface or not and plated weight by XRD and ICP. Finally, we prepared ECAs and investaged the effect of changing the compound of conductive particles on resistivity. In the study, polyaniline was prepared and synthesized at 0°C. The molecular weight of polyaniline is 3756. UV–vis spectra of the emeraldine form of polyanoline shows two peaks, 320nm and 640nm. They are the characteristic peaks of the emeraldine form of PANI. After we synthesized the emeraldine form of polyaniline, we doped it by using different doping acids(HCl、HBr、HNO3、H3PO4、DBSA、CH3COOH、HOCH2COOH) and then we solved it in DMSO to measure its conductivity and solubility. In our research of preparing conductive particles, we took the 0.982 μm flake graphite(GS-75) to plate silver electrolessly. We found that there are Ag and Ag2O on GS-75/Ag particles surface by XRD. ICP analysis shows that there are more silver coated on GS-75 surface by electroless plating process with sensitization and activation than the process without sensitization and activation. In the study of preparing electrically conductive adhesives, we can find resistivity ρ decline to 3 x 10-4 ohm-cm after plating silver electrolessly and adding polyaniline solution. The best cruing temperature of ECAs was 200°C. Finally, GS-75/Ag particles were partly alternated to 100nm Ag nanopowders. As the ratio of GS-75/Ag to 100nm Ag is 8：2, and the filling of conductive particles is 60 wt%, the lowest resisticity ρ 7.7 x 10-5 ohm-cm is represented. This is the best resistivity in this thesis.