可撓性奈米碳管叢之成長與散熱研究

Vertically Aligned Carbon Nanotubes on Flexible Metal Foil: Synthesis, Heat Dissipation Properties and Devices

李彥叡(Yan-Rui Li)

指導教授 ： 張所鋐

國立臺灣大學/工學院/機械工程學研究所/博士(2019年)

https://doi.org/10.6342/NTU201902229

摘要

本研究主要是在可撓性的鋁箔基材上合成填鐵奈米碳管叢後，利用了奈米碳管本身非常優異的軸向散熱性質加上鋁箔自身水平散熱性質當基材，來幫助發熱元件進行散熱，也比較了在相同的自然冷卻環境下，針對目前做為市場主流的散熱片進行其散熱效率的比較，本研究的試片是使用廚房用的市售鋁箔紙透過三段高溫爐在其表面使用化學氣相沉積法合成出垂直向上的奈米碳管，然後將其貼合在發熱體表面，量測發熱體本身在自然冷卻時溫度隨時間的變化，再與業界常用來當作散熱材料的銅片以及人工石墨片做比較，實驗結果顯示出透過本研究開發之可撓性奈米碳管叢散熱複合材料，去比較尚未成長碳管叢之鋁箔，其散熱效率最高可增加56%，與銅箔相比可達到40%，而與現今主流的人工石墨片比較，散熱效率也可高出20%，本研究也發現碳管叢高度與散熱效率並無太大之差異性，意謂著合成成本可被有效地降低。
另外，奈米碳管叢圖案化在許多的應用上是一個重要的課題，這也是我們所感興趣的，然而傳統的做法需要進行微影製程，不僅所需的設備昂貴，蒸鍍催化劑以及製作光罩的時間更是冗長，在此我們開發了一種前處理簡單且施作過程又快速的方法用來圖案化奈米碳管叢，經實驗發現，我們利用了常作為墨水中分散劑使用的苯乙烯-順丁烯二酐共聚物來進行奈米碳管圖案化實驗，並分析其重量百分濃度與阻絕奈米碳管成長之間的關係，之後我們開發出了兩種施作的方法將此墨水分別應用到軟、硬基材上，一種是噴塗墨水的方式，一種是雷射剝離的方式，透過我們的方法所呈現的碳管叢圖案其最小的線寬可達約 10 微米，最後我們運用此技術建立鰭片式奈米碳管叢，並量測其散熱性與進一步討論。

關鍵字

填鐵奈米碳管叢 ； 散熱 ； 自然冷卻 ； 奈米碳管叢圖案化 ； 雷射剝離

並列摘要

Vertically-aligned carbon nanotube forests (VACNT) with excellent axial heat dissipation properties were formed on aluminum foil to dissipate heat. In addition, the heat dissipation efficiency of aluminum–VACNT composites in this work was compared with that of commercially available mainstream thermal sheets under the same natural cooling conditions. Chemical vapor deposition (CVD) was employed as a synthesis method using a three-segment high-temperature furnace. Subsequently, the temperature changes in a heating body with the aluminum–VACNT composites was measured over time subject to natural cooling. In addition, the performance was compared with copper and pyrolytic graphite sheets. The experimental results revealed that the heat dissipation efficiency of the flexible aluminum–VACNT composites was higher than that of clean aluminum foil, a copper sheet, and a pyrolytic graphite sheet by up to 56%, 40%, and 20%, respectively. Moreover, this work also verified the height of the carbon nanotube (CNT) did not influence the heat dissipation efficiency, indicating that the time cost of synthesis could be reduced.
The selective growth characteristics of carbon nanotubes (CNTs) on substrates have enabled scientists to successfully pattern CNT forests. However, this is typically done using lithography, which not only involves high equipment costs, but also a lengthy process comprising catalytic evaporation and photomask production. To advance the current state of CNT patterning, this study introduces a method of patterning CNT forests that is both fast and simple. Through experimentation, we discovered that as commercially sold oil-based markers undergo nanotube synthesis, a thin film develops that prevents the catalyst, ferrocene, from coming in contact with the surface of the test specimen, thus effectively blocking CNT growth. Through further deduction we then used styrene maleic anhydride (SMA) – often employed as a dispersant in ink – to conduct CNT patterning experiments and analyze the relationship between the weight percent concentration of the SMA and the extent to which it blocked CNT growth. We subsequently developed two separate methods for applying ink to soft and hard substrates respectively: one method involved ink printing, while the other incorporated laser stripping. In the CNT pattern rendered using our method, a minimum line width of around 10 um was attained. Finally, we used this technique to establish the micro-fin carbon nanotube forests and measured its heat dissipation.

並列關鍵字

Vertically-aligned carbon nanotube forests ； thermal sheets ； heat dissipation ； ink ； micro-fin

參考文獻

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