無壓液相燒結鑽石/銀-鈦複合材料之微結構及熱性質

Microstructures and Thermal Properties of Diamond/Ag-Ti Composites Fabricated by Pressureless Liquid Phase Sintering

李牧澤

指導教授 ： 林樹均

國立清華大學/工學院/材料科學工程學系/博士(2014年)

摘要

本實驗使用無壓液相燒結法製備鑽石銀基複合材料。由於金屬銀在鑽石表面上的潤濕性不佳，由實驗得知，添加鈦以改善銀基材與鑽石間的潤濕性，進而得到具有良好的熱傳導性質的複合材料。在鈦添加量對於複合材料熱性質的影響中發現，最適量的Ti 添加量在3at.%,少於3at.%會造成系統潤濕性不足，多於3at.%會導致TiC生成過多而降低複材的熱傳導性質，鈦添加量對於複材的熱傳導性質有著決定性的影響。藉由電子顯微鏡觀察鑽石與基材間的界面厚度發現，界面層主要是由碳化鈦所組成。進一步研究燒結持溫時間對於複合材料熱性質的影響，發現複材的緻密度及熱傳導率會隨著持溫時間增加而變大，30分鐘持溫可得最大緻密度及熱傳導率；更久的持溫時間則因銀的蒸發而造成緻密度及熱傳導率降低。製備出的複合材料，在鑽石體積分率 60%、鈦添加量3at.%的條件下，其熱傳導係數可高達 836 W/mK，熱膨脹係數為 5.6 ppm/K，表示此製程製備的複合材料熱性質良好。由於此製程為一無壓燒結製程，無須加壓設備與高溫高壓模具，可大幅降低設備與模具成本；並且製程簡便，可大量生產，使此鑽石/銀基複合材料在電子構裝散熱材的應用上更具潛力。

關鍵字

鑽石銀基複合材 ； 熱傳導係數 ； 熱膨脹係數

並列摘要

In this study, Ti addition into matrix to improve the wettability between the diamond and Ag. Diamond/Ag-Ti composites were fabricated by a low-cost vacuum liquid sintering technique. The effects of Ti addition on the thermal properties of the composites were studied. The results indicate that the optimal quantity of added Ti is 3 at.%. Adding less than 3 at.% Ti resulted in poor wettability, while adding more than 3 at.% Ti resulted in excessive formation of TiC between diamond and Ag . Both reduced thermal conductivity. A composite comprising 60 vol.% diamond/Ag-3at.%Ti resulted in a maximum thermal conductivity of 836 W/mK with a coefficient of thermal expansion of 5.6 ppm/K. Furthermore, the holding time effect on thermal properties of the 60 vol.% diamond/Ag-3at.%Ti composites also were investigated. The relative density and thermal conductivity decreased with the holding time increased from 60 min to 180 min. The diamond/Ag-3 at.% Ti composite can be applied as a promising heat spreader with high reliability because it has high TC and also its coefficient of thermal expansion can be tailored for a specific semiconductor material for electronic device applications. This low-cost vacuum liquid sintering process with active Ti addition is a promising technique to fabricate high thermal conductivity diamond/Ag composites.

並列關鍵字

Diamond/Ag composite ； Thermal conductivity ； Coefficient of thermal expansion

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