石墨烯/铝电子封装复合材料界面调控及对热物理性能的作用机理

For the low density, high thermal conductivity and tailorable thermal expansivity, particle-reinforced aluminum metal-matrix composites (MMC) has received much recognition in electronic packaging, such as power module base plates, printed wiring board cores, microprocessor lids or electronic encloseures. However, it is difficult to form or machine the materials because of the presence of high volume and abrasive ceramic particles. In addition, the requirement for high thermal conductivity and light mass of electronic devices is increasing. Based on the warm compaction processing, the graphene/Al composites will be fabricated by doping the graphene as reinforced particles with two-dimensional lattice and extraordinary properties. The graphene/Al composites is expected to lower density, higher thermal conductivity and good machinability. The graphene-Al interfacical characteristic is manipulated by surface modification and processing technology, and the relationship between interfaces and thermal properties is clarified. As a result, the intrinsic properties of graphene and graphene-Al interfacial characteristics will be revealed and the experiental criteria will be established about the effect of graphene on thermal physical properties. The launching of the project provides a theoretical and experimental basis for composites fabrication of lightweight, high thermal conductivity and good machinability, and provides new ideas for development of new electronic packaging materials.

颗粒增强铝基复合材料由于具有密度低、高热导率、热膨胀系数可调等优异性能在电子封装领域（功率器件、印刷线路板及微处理器壳体封装等）受到研究者的普遍关注，但高硬度和高体积分数陶瓷颗粒添加导致铝基复合材料加工性能差，且电子器件对其高导热、轻量化提出了越来越高的材料需求。本项目拟以具有二维结构及优异性能的石墨烯为增强相，利用温压成型工艺设计制备石墨烯/铝复合材料，进一步降低颗粒增强铝基电子封装材料的密度，提高其导热性能，并改善其切削加工性能。通过石墨烯颗粒表面改性和温压工艺的设计来控制石墨烯与铝基体的界面状态，明确石墨烯的界面结构特征对热物理性能的影响规律，揭示石墨烯的本征特性及界面特征对热物理性能的影响机制，建立石墨烯对铝基复合材料热物理性能影响的经验准则。本项目的开展，将为轻量化、高导热、易加工的电子封装复合材料的研制提供理论和实验依据，并为新型电子封装材料的发展提供新思路。

针对石墨烯增强铝基复合材料具有轻质、高强、高导热、热膨胀系数可调及易加工等探索其在电子封装领域等应用，设计制备了石墨烯增强增强金属基复合材料。深入研究了石墨烯材料相结构、微观组织形貌、表面化学键结构，石墨烯表面纳米改性工艺及对复合材料性能的影响；探讨了石墨烯添加对力学性能和热物理性能的影响规律和机制，制备出大尺寸轻质、高强、高导热的石墨烯增强铝基复合材料。完成项目申报书的主要内容，并深入探讨石墨烯增强铝基复合材料时效硬化过程，同时本项目的基础研究为开发电缆用铝合金、轨道交通用结构材料及铜基电接触材料打下理论和试验基础。.采用粉末冶金和铸造法制备出石墨烯增强铝基复合材料,石墨烯分布均匀，石墨烯与铝颗粒结合较好，没有界面硬脆相Al4C3生成。石墨烯添加铝基复合材料硬度及抗拉强度均有大幅度的提高，硬度及抗拉强度最大分别提高50.1%、70.8%，石墨烯发挥增强体骨架作用并细化基体组织和析出相。石墨烯添加量小于1wt.%, 热导率保持基体合金高的导热率在200W/m.K, 石墨烯添加量增大导热系数小幅下降；随着石墨烯添加体积分数的增加，热膨胀系数减小，石墨烯添加量2%，铝基复合材料热膨胀系数在20~100℃为17.36~17.6010-6/℃。采用铸造法制备的石墨烯/2A50铝复合材料以及石墨烯/6061铝复合材料进行T6处理, 由时效硬度曲线得出石墨烯/2A50铝复合材料的最佳人工时效工艺为160℃下时效10h，石墨烯/6061铝复合材料最佳人工时效工艺为170℃下时效8h,石墨烯添加缩短了时效析出过程。