Through joint research, Tohoku University and Mitsui Mining & Smelting Co., Ltd. have developed a new process for synthesizing copper nanoparticles with low-temperature sinterability under extremely low environmental load conditions.
Research on low-temperature sintered silver nanopaste that uses silver nanoparticles as a bonding material for "printed electronics" and "next-generation power devices (power semiconductors)" that manufacture electronic circuits and insulating films using printing technology. Development is in progress.In recent years, research and development using copper nanoparticles, which are cheaper than silver, has been active, but since the copper nanoparticles preparation method uses polymers to suppress aggregation and antioxidant of the generated copper nanoparticles, organic substances that decompose at high temperatures on the surface of the copper particles. Remained and hindered low temperature sintering.
In the research, we succeeded in synthesizing low-temperature sinterable copper nanoparticles by reduction treatment of water-soluble copper complex under extremely low environmental load conditions such as water, atmosphere, and room temperature (water-soluble copper complex room temperature reduction method).As a result of heating and firing the obtained copper nanoparticles, it was clarified that the organic component decomposes at a low temperature (about 140 ° C.) and sintering of the copper nanoparticles is started.
When the copper nanoparticles developed this time were made into a paste, the copper nanoparticles were sintered on a polyethylene naphthalate (PEN) film or a polyimide (PI) film by low-temperature firing at about 180 ° C (non-pressurized firing in a nitrogen atmosphere). Good thick copper wiring (thickness 14 μm) can be made.As a result, it can be expected to replace silver paste and solder as a circuit forming material for IoT sensors by printed electronics.
In addition, as a metal-to-metal bonding material using a simulated bonding structure in which copper substrates are bonded with copper paste, high shear strength (> 200 MPa) is achieved by low-temperature firing at about 30 ° C (unpressurized firing in a nitrogen atmosphere). It is expected to be put into practical use as a bonding material for next-generation power devices (SiC and GaN).
Paper information:[Scientific Reports] Ambient Aqueous-Phase Synthesis of Copper Nanoparticles and Nanopastes with Low-Temperature Sintering and Ultra-High Bonding Abilities
