环氧树脂基电子封装材料的微结构设计及其导热和加工流动性能调控研究

The degradations of processability at high filler loading and the large interfacial thermal resistance are two key problems suppressing the thermal conductivity performance in polymer composites filled with inorganic fillers, this proposed project aims to design and fabrication epoxy-based electronic packaging materials with excellent combined properties of high thermal conductive, high electrical insulating, low coefficient of thermal expansion and good processing fluidity properties. Herein, the multiscale thermal conductivity fillers are compounded with epoxy and the processing fluidity properties could be controlled by surface wettability and size distribution effects of the binary mixtures fillers. In addition, the confined distribution of electrically insulated BNNS-NH2 with high specific area in the limited space among spherical alumina and the covalently bonding interaction between different fillers during the curing process to form continuous thermal conductive paths within the epoxy micro/nano composites. This research is believed to provide novel approaches, which rely upon the filler surface modification, the synergetic effect of spherical filler and the confined distribution of BNNS-NH2, for controlling the spatial location of different dimension fillers in the epoxy matrix. The size distribution effects of binary mixtures of spherical alumina on processing fluidity properties and covalently bonding interaction between various thermal filler on interfacial thermal resistance and thermal conductivity enhancement mechanism of epoxy micro/nano composites are expected to be depicted, these results and outcomes will provide convenient methods and theoretical guidelines for the developments of high-performance epoxy-based Underfill electronic packaging materials.

无机导热填料在提高复合材料导热性能的同时存在高填充量所导致的加工流动性能劣化和界面热阻过大的关键问题，本项目设计了兼具高导热、电绝缘、低加工粘度和热膨胀系数的环氧树脂基电子封装材料。采用多尺度填料体系与环氧树脂复合，通过改变填料的表面特性、粒径分布和粒子间距来降低流动阻力，同时利用大比表面积的氨基氮化硼纳米片在高填充量球形氧化铝的未填充区域的受限分布和固化过程中的共价键合作用，制备具有共价键桥连导热网络的环氧树脂微纳米复合材料；建立通过填料的表面改性、多尺度填充和二维填料氨基氮化硼纳米片的受限分布共同作用来实现不同维度导热填料在树脂基体中可控分布和构筑导热通路的新方法；揭示高分子复合材料加工流动性能与多尺度填料的粒径分布关系、填料之间共价键桥连结构与复合材料界面热阻和导热增强机理的影响规律，为高性能环氧树脂基Underfill(底部填充)电子封装材料的研究和开发提供简单方法和理论基础。

电子设备日益向高功率化和微型化趋势发展，对工作运行期间的器件提出了越来越高的热管理性能。而封装材料在电子元件中主要起到组合，机械保护，提供信号分配以及帮助散热的作用，在电子器件的使用性能和工作稳定性之间起到作用。其中，环氧树脂底部填充封装材料被广泛应用于倒装芯片工艺中。但是，目前商业化的低填材料存在导热性能低的问题，难以满足下一代电子设备的日益严峻的热管理需求。基于这些，我们提供了一些解决手段；.1. 填料多尺度填充。通过填充不同维度和尺寸的导热填料，提高填料实际填充密度，实现多尺度填料间的协同效应和级配效应，缓解了环氧树脂复合材料在高填充条件下导热性能和加工性能的矛盾。.2. 连续填料网络的构建。通过树脂固化后的短时间热处理方法(300℃,10min)，利用银纳米颗粒的熔融合并过程在导热填料之间形成纳米金属连接结构， 降低复合材料中导热填料物理搭接网络之间的接触热阻。.3. 填料物理结构和复合材料界面强化。通过非共价键化学修饰改性碳纳米管，减少化学改性处理对填料的结构缺陷破坏，缓解填料分散和界面状态的提高与填料本征结构的破坏在提升复合材料导热性能间的矛盾。