Co-electrodeposited graphite and diamond-loaded solder nanocomposites as thermal interface materials

This paper describes a novel co-electrodeposition process to form thin bonding structures based on solder-graphite and solder-diamond nanocomposites for thermal interface materials (TIM). Using this novel processing route, inorganic nanoparticles can be co-plated along with a solder matrix to form unique nanocomposite structures with much enhanced thermal conductivity, engineered thermomechanical properties such as coefficient of thermal expansion (CTE), strength and fatigue resistance, while enabling the benefits of electroplating such as thin film and fine-pitch processing, low-temperature deposition and compatibility with semiconductor and packaging infrastructure. Si-Si and Cu-Cu bonding were demonstrated with these solder nanocomposites having high graphite loading. Pressure-assisted bonding enhanced solder wetting on nanoparticles and improved the bonding characteristics.