石墨烯和定向碳纳米管复合薄膜制备及其界面热传输研究

The development of high performance thermal interface materials (TIM) is one of the important methods to solve the problem of heat dissipation in microelectronic packaging. Duo to their relatively low thermal conductivity and poor thermal stability, traditional thermal interface materials have poor heat dissipation capacity. They are difficult to meet the requirements of packaging of high power devices, so the development of high performance thermal interface materials becomes extremely urgent. In this project, aligned carbon nanotube arrays are filled with graphene oxide after patterning and densification. After that, high temperature carbonization and graphitization treatments are used to prepare graphene/aligned carbon nanotube composite films. Based on the high transverse thermal conductivity, aligned carbon nanotube arrays provide additional longitudinal heat transfer channels to achieve the enhancement of the longitudinal thermal conductivity. Besides, during high temperature carbonization and graphitization treatments, the mechanissm of covalent bond formation and reconstruction evolution is clarified between graphene and aligned carbon nanotubes. Subsequently, the surface functionalization process of graphene/aligned carbon nanotube composite films is developed to achieve a lower interfacial thermal resistance between the composite film and substrate, and its mechanism is also clarified. Finally, the thermal conductivity and interfacial thermal resistance of the composite films are accurately measured, and the mechanism of interfacial heat transfer is elucidated. Besides, thermal performance and reliability of the composite films are also verified in the system.

开发高性能热界面材料是解决微电子封装散热问题的重要手段之一。传统的热界面材料由于较低热导率和较差热稳定性，导致其散热效果不佳，越来越难以满足大功率器件封装需求，因此研发高性能热界面材料变的极为迫切。本项目通过氧化石墨烯填充图形化和致密化后的定向碳纳米管阵列，经过高温碳化和石墨化处理制备得到石墨烯和定向碳纳米管复合薄膜。在保证其较高横向热导率基础上，利用定向碳纳米管阵列提供了额外的纵向传热通道，从而实现其纵向热导率的提升，并且阐明在高温碳化和石墨化处理过程中石墨烯与定向碳纳米管之间的共价成键和重构演化机制。随后开发用于石墨烯和定向碳纳米管复合薄膜的表面功能化处理过程，实现其与基底较低的界面热阻，并阐明其表面功能化修饰机理。最后，精确测量复合薄膜的热导率和界面热阻，阐明界面热传输机理，并进行系统下热性能和可靠性验证。

开发高性能热界面材料是解决微电子封装散热问题的重要手段之一。传统的热界面材料由于较低热导率和较差热稳定性，导致其散热效果不佳，越来越难以满足大功率器件封装需求，因此研发高性能热界面材料变的极为迫切。本项目对垂直定向碳纳米管阵列的生长机理进行了深入研究，通过环氧树脂和石墨烯填充图形化和致密化后的碳纳米管阵列，从而得到了垂直定向碳纳米管阵列和石墨烯增强环氧树脂复合薄膜。同时，利用高温还原法制备得到石墨烯和碳纳米管复合膜，在保证其横向热导率1054.8 W•m-1•K-1的基础上，实现了其纵向热导率的提升，并阐明了其导热机制。随后，开发出用于薄膜的表面功能化处理工艺，实现其与基底较低的界面热阻，并在热测试芯片等系统模块下进行了热性能验证。