經由無機材料表面改質以提升高分子複合材料之熱導性質

Abstract

氮化硼及氮化鋁優異的導熱性廣泛地被添加於高分子複合材料來增加其熱傳導性，以達到尖端應用產業對材料的高功能性需求。已執行一年半的國科會產學計畫中，對於高分子複合材料(RTV矽膠+BN) 導熱性質的提升我們已有初步的研究成果: 分析添加不同粒徑組合未改質的氮化硼於RTV矽膠所製成之複合薄膜的機械與熱性質變化，並比改質氮化硼的影響。初步研究結果顯示，添加不同粒徑的BN於RTV/BN 高分子複合材料中，將可得到高的熱傳導係數(thermal conductivity, k, 0.63 W/mK)，而此複合材料中所含的BN 粒子組合若再經過改質後，則可得更高的熱傳導係數k 值(0.73 W/mK)，顯示此RTV 矽膠與初步改質BN 間的作用力增加而使此高分子複合材料具有極佳的尺寸安定性與熱傳導能力。針對本研究計畫，我們使用兩種不同的無機導熱材料(即氮化硼BN與氮化鋁AlN) 進行不同官能基的無機材料表面改質(包含-C=C-，Si-H，-NH2)，進行不同種類無機及高分子材料的搭配，不同尺寸的無機材料，不同無機及高分子比例的混摻，及材料表面改質。針對目前業界所需的封裝 i 特性、熱傳導特性、熱應力等不同的需求，去做最佳化的探討及研究，透過上述不同參數的調變，加上利用(1) 型態學：SEM 探討無機材料型態、(2) 結晶度：XRD 探討無機材料結晶型態、(3) 熱應力：TMA 探討高分子複合材料的熱膨脹係數、及(4) 熱傳導係數：熱傳導分析儀等量測。最後，此計畫之研究成果，我們獲得最佳化的熱傳導(1.14 W/mK)、熱應力及機械性質的高分子複合材料。

Highly thermal conductive inorganic materials (including BN and AlN) have been applied and well distributed in polymeric materials to improve the thermal conductivity of the polymer composites for advanced applications. Our previous results (1.5 years of NSC projects) demonstrate the effects of surface modification and addition ratio of BN on the thermal and mechanical properties of polymer composites (containing RTV rubber and inorganic BN) were investigated. The surface modification of BN enhances the interaction between RTV and BN in the polymer composites. The results show that the combination of BN particles with different sizes in RTV/BN composites can obtain the highest thermal conductivity of 0.73 W/mK. In this proposal, we focus on two different inorganic materials (boron nitride BN and aluminum nitride AlN with excellent thermal conductivities) surface-modified with three different kinds of sufactants containing various functional groups (including -OH, NH2 and -C=C). Different types, ratios, and surface modification of inoganic materials (boron nitride and aluminum nitride with various sizes) and polymers (containing –OH, -NH2, -C=C) were blended to produce various polymer composites. Therefore, according to the adjustment of previous parameters, polymer composites can be optimized to possess many iii different merits, such as packaging, thermal conductivity, thermal stress, and transparency, via the following characterization techniques: (1) Morphology: SEM; (2) Crystallinity: XRD (to investigate the crystallization of inorganic materials); (3) Thermal mechanical property: TMA; (4) Thermal conductivity: Thermal conductive equipments. Finally, we expect to obtain polymeric composites with the optimized thermal conductivities (promoted up to 1.14 W/mK), thermal stress, transparency, and mechanical properties.