鑽石導熱膏熱傳導性質之研究

Thermal Conductivity of Diamond-containing Grease

周弘恩(Hung-En Chou)

指導教授 ： 王錫福

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00475

摘要

作為一種熱界面材料(thermal interface materials；TIM)，導熱膏(thermal grease；TG)被廣泛應用在電子元件的散熱上。與習用的填充物相比，鑽石具有更優越的熱傳導係數，實際應用於導熱膏的量測數據卻相對稀少。本研究以鑽石粉為必備的填充物，設計15~25 μm與2~4 μm兩種粒徑範圍，搭配作為載體的二甲基矽油(polydimethylsiloxane, PDMS)，製備出「單粒徑」、「雙粒徑」、「雙矽油」、「雙填充物」與「三填充物」五種膏體，並以hot disk法測量其熱傳導係數。
在相同的總體積填充率下，使鑽石粉由單粒徑改為雙粒徑，k(TG)可提升至2.76 W/mK，且小粒徑鑽石粉的填充分率以20%為最佳。3.0 W/mK這個障礙可藉由將PDMS的末端官能基由非極性-CH3改為極性OH基而突破。將黏度分別為60 cps與5000 cps的OH-terminated PDMS依不同重量比例加以混合，可獲得黏度介於兩者之間的新載體，當此mixed PDMS的黏度為350 cps，所對應「雙矽油膏體」的k(TG)可提昇至3.15W/mK。若延續此膏體的填充物比例，保留大粒徑鑽石粉，而將小粒徑鑽石粉分別以Al2O3與ZnO取代，在這兩種「雙填充物」膏體中，雖然前者的效果有限，但後者卻可帶來本研究最高的k(TG)(~3.52W/mK)，為k(PDMS)的23倍。

關鍵字

熱界面材料 ； 複合材料 ； 導熱膏 ； 熱傳導 ； 鑽石

並列摘要

As one thermal interface material (TIM), thermal grease (TG) is widely applied to heat dissipation of electronic devices. Despite the superior thermal conductivity of diamond, reports about diamond-containing TG were rare. In the present study, thermal conductivity of five TGs was measured by hot disk technique. At first, the diamonds of two sizes were used alone or in combination to mix with CH3-terminated polydimethylsiloxane (PDMS). Under the same total filler content, the latter showed a better k(TG), especially at a small diamond content of 20 vol%. If a hybrid OH-terminated PDMS was adopted, 350 cps was a preferred viscosity to break through 3 W/mK. Unlike these single-filler TGs, if large diamonds were retained and small diamonds were replaced by Al2O3 or ZnO, it was found that diamond was not always the best choice of small filler. The highest k(TG), which was 23 times greater than k(PDMS) appeared in a ZnO-containing double-filler grease (=3.52 W/mK). The prediction for the maximum attainable k(TG) proposed by Bigg et al. was preliminarily supported. Scanning electron microscopy (SEM) images revealed that unlike homogeneous distributions of small-sized diamonds, the agglomeration of ZnO powders occupied regions with large area between diamonds and formed continuous thermal paths, which resulted in a better k(TG). Although k(TG) could be further improved to approximately 4 W/mK by replacing either large-sized diamond or ZnO by a small amount (5 vol.%) of h-BN, the so-called tri-filler grease was not available for application due to the hardened structure and poor flowability. From thermogravimetric analysis (TGA), no significant weight-loss was recorded for three double-filler TGs prepared in this study until 200℃, under which an central processing unit (CPU) operated. Their thermal stability was thus roughly suggested.

並列關鍵字

Thermal Interface Materials ； Composite ； Thermal Grease ； Thermal Conductivity ； Diamond

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