高密度封装中碳基界面散热材料的金属化改性及复合界面导热机理的研究

With the microelectronic packaging integration density increasing higher and higher, the heat flux on chip hot spot becomes larger and larger; while most of the electric energy convents into heat dissipation and results in exceedingly high chip temperature, it will consequently affect the reliability of IC seriously. Therefore, it is of great necessity to develop the advance and excellent thermal interface material to solve the IC chip thermal management. Currently, the thermal conductivity of most thermal interface materials, including thermal pad, thermal grease, thermal glue, phase change materials and so on, range from 2 W/mk to 6 W/mk, showing unsatisfactory heat spreading effect in electronic packaging. So it is of great importance to develop high thermal conductivity spreading material to solve the high temperature problem. .Recently, nano fiber material attracts great research interest due to its significant physical and chemical properties and our research group is also trying to develop new novel nano fiber material to apply in high electronic packaging density. Now we have successfully fabricated one kind of thermal interface material, which is made up of carbon nano fiber solder matrix composite (CF-TIM), this new material has 41±2 W/m•K thermal conductivity in xy direction and 20±3 W/m•K in z direction. Its thermal conductivity is much higher than general carbon fiber films and presents promising future in electronic packaging application. Thus, this project will aim to both the develop and the application of these carbon based thermal interface material in high density microelectronic packaging and its key technology; meanwhile, the heat transfer mechanism between different interface in these special material will also be studied, which can be used to offer theory explanation help for other composite thermal interface material in the future.

随着微电子封装集成密度越来越高，芯片单位体积上功耗密度急剧增加，而功耗大部分转变为热能，由此带来过高温度严重影响芯片工作稳定性。因此，需要采用先进散热封装工艺和性能优异散热材料，解决芯片过热问题。目前，一般的界面散热材料，如散热垫、导热油脂、散热带、导热胶等，这些材料热导率普遍在2-6W/mk范围，散热效果并不理想。因此，研发新型高热导率散热材料显得极为重要。近年来，纳米纤维材料是个研究热点，本课题组也尝试开发新型纳米纤维散热材料，并应用于高密度电子封装散热中。目前，本课题组成功制备具有中间相的碳纤维基复合界面散热材料，该材料水平方向热导率为41±2 W/mK，垂直方向为20±3 W/mK，远高于碳纤维薄膜散热材料热导率，很有前景。因此，本项目拟针对碳基材料及其相关技术在高密度、高功率封装和制造等关键技术应用方面，及高导热性能碳基界面散热材料导热机理开展研究，为复合界面散热材料提供参考。

随着微电子封装集成密度越来越高，芯片单位体积上功耗密度急剧增加，而功耗大部分转变为热能，由此带来过高温度严重影响芯片工作稳定性。一般地，通过采用先进散热封装工艺和性能优异散热材料来解决芯片过热问题。目前，一般的界面散热材料，如散热垫、导热油脂、散热带、导热胶等，这些材料热导率普遍在2-6 W/mK范围，散热效果并不理想。因此，开发新型高热导率散热材料是顺应新形势下高密度高功耗微电子封装发展的一项重要课题，具有非常重要意义。.本项目的研究内容涵盖两部分，一部分是新型金属化碳基界面散热材料制备及形貌表征，另一部分是新型金属化碳基界面散热材料实际应用时热性能表征。通过本项目的立项研究，本课题组开发了一种新型金属化碳基界面散热材料，该种新型界面散热材料采用石墨烯纤维网络，再渗透金属合金，获得了高热导率40 W/mK，具备很好的应用前景。新型金属化碳基界面散热材料既能克服传统的导热衬垫和导热油脂等散热材料在芯片和散热片之间热传导率低、热稳定性差以及厚度较大等缺点，也将很好弥补纯金属导热材料成本高、可靠性低的劣势。通过本项目的立项，很好地解决了碳基界面散热材料在热管理应用中的关键技术，以满足不断发展的高密度高功耗微电子和微系统封装面临的挑战，为制备开发出可用于高密度微系统封装的具有优良导热性能的界面散热材料提供技术基础。