A novel nanocopper-based advanced packaging material

A novel nanocopper-based packaging material was developed for robust, void-free thermal interfaces between LEDs and heat sinks/spreaders. It is applicable to other high power components and devices allowing sub-10 micron thermal interfaces to enable high heat transfer rates. Other applications are in TSV & wafer level packaging, embedded chip packaging, direct print of Si and Glass interposers, wafer level bonding and die attachment as well as printed and flexible electronics. This solder-free nanocopper material overcomes the fundamental limitation of traditional solders, where the processing temperature sets an upper bound to the maximum possible operating temperature. Since nanocopper reverts to bulk copper upon fusion, it is capable of operating above its original processing temperature making it the ideal high temperature packaging technology. Being pure copper in its fused state, the material can form contacts with 5-10x the thermal and electrical conductivity of typical solder systems. The material's rheology can be tuned for drop-in replacement of solder paste on standard PCB assembly lines and other industrial dispensing and printing equipment. The resulting copper-based interconnects can exhibit improved creep resistance and enhanced reliability and robustness in low- and high-temperature operating environments. For LED bonding to thermal heat sinks/spreaders, a readily dispensable nanocopper die attach material was formulated for controlled and repeatable dispensing of less than 0.1 mg per die that led to interface layers as thin as 2- 3 micron.