| Summary: | 碩士 === 國防大學理工學院 === 化學工程碩士班 === 100 === The thesis is divided into two parts. In the first part, graphene was prepared by the method of chemical oxidation/thermal reduction, and added into conductive pastes. The effects of varying processing parameters were studied and the optimum conditions were obtained. Through the XPS, EA, SEM observations, we analyzed the oxygen functional group contents and the dispersion of graphene in the adhesive, and finally used a four-point probe to measure the resistivity of the conductive paste. The results showed that the graphene reduced at a heating rate of 10℃/min was the most effective to form a conductive network and gave the lowest resistivity1.5ⅹ103 Ω-cm. At the reduction temperature of 1100℃ for 1 hr with a hydrogen flow of 20 sccm, graphene with a low content of oxygen functional groups (0.66%) was obtained and the corresponding conductive paste showed a better resistivity of 3.6 Ω-cm . In addition, we doped graphene with nitrogen to improve the conductivity. The best nitrogen-doped graphene was achieved at an ammonia flow of 100 sccm, where a 0.707% N content was obtained and the resistivity of the corresponding conductive paste was 2.6 Ω-cm.
The second part of the thesis compares the conduction performances of various carbon fillers in composite conductive pastes, with or without silver particles. The conductive paste filled with nitrogen-doped graphene showed much better conductivity and lower percolation threshold than the counterparts with carbon black and carbon nanotubes. SEM observations revealed that the nitrogen-doped graphene can effectively form a conductive network at 1 wt% loading. We further found that, in the silver-based conductive pastes, adding 1 wt% of graphene effectively reduced the required silver loading from 45 wt% to 10 wt% while maintaining the same resistivity. The experiments showed that a small amount of the graphene filler can effectively reduce the required amount of silver in conductive pastes and achieve the goal of cost reduction.
Keywords: Graphene、Silver、Conductive Adhesive、Resistivity
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