导热微粒烧结和复合材料取向对大功率LED散热的影响

发布时间：2018-06-04 18:56

  本文选题：环氧树脂 + 复合材料　； 参考：《重庆大学》2015年硕士论文

【摘要】：随着LED的广泛应用,如何提高它的寿命是目前普遍关注的问题。由于LED的芯片在使用的过程中产生热量,热量的大量积累导致其寿命缩短,所以LED封装材料的导热系数低是影响其寿命的最大挑战。因此LED封装材料的导热性能的改善,是亟待解决的难题。目前已有的解决封装材料散热问题的方法是将导热微粒填充到聚合物中,制备高导热的聚合物基复合材料。聚合物基复合材料的导热性能跟很多影响的因素有关,主要分为导热微粒和聚合物两个方面的因素。导热微粒包括本身的导热性能、形状、大小、添加量、分散性、取向性、界面结合、界面面积、种类。聚合物包括导热性能、取向性等。为了解决LED封装材料散热问题,本课题以环氧树脂为基体,分别以二氧化硅(Si O2)、碳化硅(Si C)为导热微粒,制备了高比例导热微粒陶瓷片和取向型高导热聚合物基复合材料,其中高比例导热微粒陶瓷片用在LED的陶瓷片上,而取向型复合材料用在LED的封装上。为了改善导热微粒与环氧树脂基体之间界面,该课题用硅烷偶联剂对导热颗粒进行表面处理,并对硅烷偶联剂的作用机理进行了详细的分析,研究结果表明表面改性过的导热微粒填充环氧树脂,制备的复合材料的导热系数要高于未改性的复合材料。在制备高比例导热微粒陶瓷片的过程中,用导热微粒的质量的5%的铝粉(Al)、氧化钇(Y2O3)、氧化镁(Mg O)作为烧结剂,经高压成型,在高温炉中660℃烧结,经研究发现用氧化钇(Y2O3)+氧化镁(Mg O)作为烧结剂可使陶瓷片中导热微粒在环氧树脂中的致密性达到最大,制备出导热系数达到12.753W/m K碳化硅共烧陶瓷片。通过扫描电子显微镜可以明显的随着烧结温度的增加陶瓷片的孔的数目先增加再减小。本课题还从聚合物取向机理入手,探究了聚合物取向与玻璃化温度之间的关系。为了使复合材料的具有取向结晶,打开声子导热通道,从而提高复合材料的导热系数,在本课题中通过测量复合材料的玻璃化温度来掌握发生取向的温度和时间,使复合材料机械拉伸下发生取向,制备出了取向复合材料。通过光学显微镜可以观察到横截面积不同的取向复合材料纤维,研究结果发现取向复合材料的导热系数随着导热微粒的添加比例增加而增加。取向复合材料的导热系数高于未取向的复合材料,取向复合材料的导热系数随着拉伸比的增加而增加。当Si O2的质量分数为80%时,取向复合材料的导热系数为1.2 W/mk,是纯环氧树脂的5.97倍。当微米Si C的质量分数为60%时,拉伸比为4的取向复合材料的平行于取向方向上的导热系数(K∥)为5.78 W/mk,它是纯环氧树脂的28.8倍。在本课题中还对Si O2/环氧树脂取向复合材料的介电性能进行了测试,测试结果表明取向对环氧树脂的绝缘性能影响并不大。
[Abstract]:With the wide application of LED, how to improve its life is a common concern. The low thermal conductivity of LED packaging materials is the biggest challenge that affects the lifetime of LED because of the heat generation in the process of using the chip and the accumulation of a large amount of heat resulting in the shortening of its life. Therefore, the improvement of thermal conductivity of LED packaging materials is an urgent problem to be solved. At present, the existing method to solve the heat dissipation problem of packaging materials is to prepare polymer matrix composites with high thermal conductivity by filling thermal conductive particles into polymers. The thermal conductivity of polymer matrix composites is related to many factors, which can be divided into two aspects: thermal conductivity particle and polymer. Thermal conductivity particles include their own thermal conductivity, shape, size, addition, dispersion, orientation, interface bonding, interface area, category. Polymers include thermal conductivity, orientation, etc. In order to solve the heat dissipation problem of LED packaging materials, high proportion thermal conductive ceramics and oriented high thermal conductivity polymer matrix composites were prepared by using epoxy resin as substrate, silicon dioxide and silicon carbide as thermal conductive particles, respectively. Among them, the high proportion of thermal conductive particulate ceramics is used on the LED ceramic chip, while the oriented composite is used in the LED package. In order to improve the interface between thermal conductive particles and epoxy resin matrix, the surface of thermal conductive particles was treated with silane coupling agent, and the mechanism of silane coupling agent was analyzed in detail. The results show that the thermal conductivity of the composites filled with epoxy resin is higher than that of the unmodified composites. In the process of preparing high proportion thermal conductive particle ceramic chip, 5% aluminum powder, yttrium oxide Y _ 2O _ 3, MgO _ 2O _ 3 were used as sintering agent, which were sintered at 660 鈩，

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