A Variety of Silver Nanoparticle Pastes for Fine Electronic Circuit Pattern Formation

Metal powder-based thick-film pastes are limited to make the electronic circuit pattern on the refractory ceramics or glass, because of their firing temperature. In addition, the line width and space of the circuit pattern are limited over 50 mum. However, the electronic devices are recently demanded to be compact, lightweight and flexible. For this demand, recent progress of nanotechnology has accelerated to develop a new type of materials for electronic devices. From this point of view, much attention has been paid to metal nanoparticles with diameters ranging from several nanometers to tens of nanometers, which may be expected to be fired at low temperature less than 300degC based on their physical property. Using a series of silver nanoparticles, we have developed the low temperature firing silver nanoparticle pastes, including silver nanoparticles stabilized by a series of organic ligands. The silver contents of the manufactured silver nanoparticle pastes are easily controlled ranging from 50 to 90 wt%. The electronic circuit pattern can be formed on a polyimido film by screen printing technique and fired at low temperatures of 150 to 300degC. The formed conductive films exhibit the resistivity compared with that of bulk metal. The film thickness ranges from 2.6 to 30 mum and their resistivity is 2.46 to 40 muOmegacm. This paper describes a variety of silver nanoparticle pastes and the properties of their fired film.