【作者】 皮智华；

【导师】 刘胜；

【作者基本信息】 华中科技大学 ， 光电信息工程， 2011， 硕士

【摘要】 界面热阻对电子器件封装热管理有着重要的影响,它在封装总热阻中扮演着重要角色。广泛使用的粒子填充型热界面材料,具有高热导率、低成本、易操作等优点,可以有效降低封装散热中的界面热阻。但此类材料使用时易发生粒子堆积,生成厚的粘合层厚度(BLT),在热循环中产生空气孔洞和粘结裂纹等失效方式,反而增大了热界面材料的热阻RTIM。表面沟槽能够显著改善粒子填充型热界面材料应用时遇到的上述问题。本文以表面沟槽为研究对象,主要研究工作与结论包括:(1)回顾了热界面材料(TIM)的定义、作用、业界的研究进展,以及粒子填充型热界面材料所遇到的问题;然后在流体流动理论的基础上论证了表面沟槽能通过降低压力梯度、阻止粒子堆积来减小TIM的粘合层厚度。(2)提出了一种能够评估表面沟槽影响热阻的实验方法,即通过测试有无表面沟槽的固—固接触面之间热界面材料的热阻值(RTIM)并进行对比。对比试验结果表明,表面沟槽能够显著降低RTIM,实验测试的结果中热阻降幅最高可达56.1%。(3)对于使用较低热导率TIM的热界面,表面沟槽对RTIM的降幅更大,其原因是表面沟槽减小的粘合层厚度具有更大的热阻。(4)对于同一热界面,界面压力的增大也能显著降低RTIM,且使用低热导率TIM的热界面,RTIM降低的趋势更显著。(5)表面沟槽降低了粘合层厚度,去除了界面间部分的高热导率固体材料,增大了界面间换热面积。采用有限元法模拟计算上述变化对热阻的影响,结果显示界面热阻也能显著降低,模拟结果与前面的实验结果比较吻合。本文提出的表面沟槽及其评估方法,对电子封装热管理设计有一定的参考价值。更多还原

【Abstract】 Interfacial thermal resistance has a significant impact on thermal management of electronic device packaging, and it plays an important role in the total packaging thermal resistance. Particle-filled thermal interface materials which are widely used in electronic devices packaging,have the advantages of high thermal conductivity, low cost, easy to operate, etc., and they can effectively reduce the interfacial thermal resistance in thermal management of packaging. Drawbacks of these materials are the stacking of particles, formation a thick bondline thickness(BLT), and the susceptibility to air voiding and cohesive crack in the thermal cycling, on the contrary to increase the thermal resistance of thermal interface materials(RTIM).Surface channels can significantly improve the above problems which particle-filled thermal interface materials have encountered in the applications. In this thesis, the surface channels are chosen as the research object and the main work are as follows:(1) Firstly, the definition, function and research progress of thermal interface materials in industry have been reviewed, the problems which particle-filled thermal interface materials encountered in their applications have also been introduced; Secondly, the principle of surface channels reducing BLT through decreasing pressure gradient and preventing particle stacking has been demonstrated on the basis of fluid flow theory.(2) An experimental method designed for evaluating the impact of surface channels on thermal resistance has been proposed, which by testing thermal resistance of the TIM(RTIM) in a solid-solid contact interface which may have surface channels and making comparison between them. The test results shows that surface channels can significantly reduce the thermal resistance of TIM(RTIM), in some cases of the test experiments the decreasing amplitude can be up to 56.1%. (3) For the interface used the TIM which has relatively low thermal conductivity, surface channels can lead more decrease on RTIM. The reason is that the decreased BLT caused by surface channels have greater thermal resistance.(4) Increasing the pressure on the thermal interface also can significantly reduce the RTIM. Furthermore, for the interface used the TIM which have lower thermal conductivity, the trend of decreasing of RTIM is more remarkable.(5) Surface channels reduced the BLT, removed part of the material in the solid-solid interface which have relative high thermal conductivity, and increased the heat transfer area between the thermal interface. In this thesis, finite element method(FEM) has been used to simulate the impact of this changes on the interfacial thermal resistance. The results showed that surface channels can also significantly reduce the interfacial thermal resistance, the simulation results agree well with the experiments.It is expected that the surface channels and its assessment methods proposed in this thesis have some reference value on the design of thermal management of electronic device packaging.更多还原