| 摘要: | 隨著電子晶片設備的功能越來越強大，其消耗的功率不斷上升，導致熱通量增加。散熱已成為電子設備中解決冷卻要求的重要研究領域。傳統由矽脂組成的散熱材料已經無法達到高功率運算晶片所需的散熱效率。相較之下，奈米碳管(CNT) 和石墨烯(GnP)奈米碳材料具有固有的極高電導率（≧104 S/cm）和熱導率（≈3500 W/mK）。它們的高電導率與高比表面積的特性，可以應用在超級電容器和燃料電池的電極。此外，隨著微電子的小型化和便攜式設備的進步，對高能量密度電池的需求迅速增加，它們的輕質化特性使其具有吸引力。
巴基紙是一種碳基薄膜，主要由奈米碳管之間的分子間凡得瓦力所形成的薄膜。同樣，石墨烯紙是由石墨烯利用凡德瓦力所組成的薄膜，具有高表面積、強化學穩定性和令人印象深刻的導熱性。
本研究旨在使用抽氣過濾技術製造 CNT/GnP 複合紙，並跟打印巴克紙做比較，它們既不需有附著物；本身也具有可饒性，可以適應各種不同的環境。值得注意的是，在製造過程中不添加任何黏合劑。通常，黏合劑可以增強奈米碳管的黏合，並增加柔韌性。然而，由於大多數黏合劑是絕緣材料，它們在兩種物質之間形成屏障並阻礙熱量流動，從而與現有的散熱墊相比具有優異的導熱性。這些創新的無黏合劑複合材料具有卓越的導熱性能，能夠有效、靈活地填充界面。同樣地，CNT和石墨烯的電導率可以在很大程度上保留，只要能夠將接觸電阻降到最低。因此，在本研究中，對抽氣過濾生成的CNT/GnP薄膜的電導率進行了實驗評估。結果表明，經過輾壓後的導電度相比於未輾壓的導電度有所提高。其中，導電度表現最好的石墨烯片測出來的導電度為149.81 S/cm。除了測量導電度，也觀察了導熱值，在室溫下，測量不同比例的打印奈米碳管/石墨烯複合薄膜，當CNT:GnP=67:33時擁有最高的導熱數值為116.73 W/mK。這些數值與鎳箔的數值相似，比商用導熱墊高四倍。也實際上機測試，並在CPU運算量滿載的狀況下測量溫度，相比沒加巴克紙的CPU溫度，溫度從62度降到了49度，下降了13度。因此，這項研究表明，這些創新的碳質複合材料具有卓越的導熱性能，使其成為有效散熱管理的突破性選擇。
;As electronic chip equipment becomes more and more powerful, the power it consumes continues to rise, leading to an increase in the amount of heat energy dissipation. Heat dissipation has emerged as a significant area of research in electronic equipment to address the cooling requirements. Conventional heat dissipation materials composed of silicon can no longer achieve the desired heat dissipation efficiency for high-power computing chips. By contrast, nanocarbon materials, such as carbon nanotubes (CNTs) and graphene platelets (GnPs), inherently possess exceptionally high electrical conductivity (≧ 104 S/cm) and thermal conductivity (≈ 3500 W/mK). Their high electrical conductivity, combined with large surface-to-volume ratio, provides an application for an assembly of the nanomaterials as electrodes in supercapacitors and fuel cells. In addition, following the miniaturization of microelectronics and advances in portable devices, their lightweight property makes them appealing with the rapid increase in demand for compact and high energy density batteries.
Buckypapers are a form of carbon-based thin film, known for their unique integration of single-wall or multi-wall carbon nanotubes through the intermolecular Van der Waals force. This process results in a paper-like structure. Similarly, graphene papers are another type of carbonaceous material that possess a high surface area, strong chemical stability, and impressive thermal conductivity. Given the exceptional thermal conductivity of these carbonaceous materials, we anticipate that papers produced from carbon nanotubes and graphene will have superior heat dissipation capabilities.
The objective of this work is to use filtering technology for the production of CNT/GnP composite paper, and to conduct a comparative analysis with printed buckypaper. Attachments are not necessary for them; nevertheless, they possess flexibility and the ability to adapt to many situations. It is important to note that no adhesives are used in the production process. Adhesives often improve the adherence of carbon nanotubes and enhance their flexibility. Nevertheless, due to the insulating nature of most adhesives, they create a barrier between the two substances, hindering the transfer of heat and hence exhibiting better thermal conductivity in comparison to current thermal pads. These novel binder-free composites provide exceptional heat conductivity and provide quick and adaptable interface filling. Similarly, the electrical conductivity of the CNTs and graphene, can be largely preserved, providing that the contact resistance can be minimized. Thus, in this study, the electrical conductivity of the CNT/GnP films, generated by filtration, has been evaluated by four-probe point testing. It has been shown that the electrical conductivity of the fabricated CNT/GnP films improved after rolling as compared to its as-fabricated state. Out of all the samples, the graphene sheet with the highest conductivity had a measured value of 149.81 S/cm. Furthermore, the observation of the thermal conductivity value was conducted in addition to the measurement of electrical conductivity. The measurements of printed carbon nanotube/graphene composite sheets with varying fractions were measured at room temperature using the Hot Disk transient plane heat source technique.
At a ratio of 67:33 between CNT and graphene, the thermal conductivity reached a peak value of 116.73 W/mK. These values are comparable to those of nickel foil and three times greater than those of commercial thermal pads. Furthermore, the experiment was conducted on the surface of the CPU of a computer, and the temperature was recorded under maximum CPU usage. The temperature decreased from 62℃ to 49℃ than compared to the CPU temperature without buckypaper. This work displays the exceptional electrical and thermal conductivity qualities of these novel carbonaceous composites, establishing them as a groundbreaking choice for both electrical applications and thermal management. |
