Tanaka Precious Metals has introduced what it claims is the world's first conductive silver ink capable of forming electronic circuits using only hardening by ultraviolet (UV) light without the need for hardening by heating. A total of three silver inks using different types of resin and reaction initiator will be available and users can select the materials according to their manufacturing equipment and application.
A variety of technologies are currently being developed to enable popularization of printed electronics. Metal nanoparticles are being developed, but it is necessary to form circuits without heating in order to form circuits on all types of base material such as PET film susceptible to heat. Heating conditions for ink hardening have been an issue in wiring materials because they all required a heating process such as materials requiring heating at 50ºC to 100ºC for several minutes and materials requiring heating to supplement hardening by UV irradiation.
This conductive silver ink commercialized by Tanaka is formed by being irradiated with UV light under room temperature conditions without heating due to optimization of the composition and mixture of resin containing silver particles and reaction initiator. As there is no need for the large equipment or thermal processing time required in thermal hardening, it is possible to significantly improve production speed per unit of area. A total of three silver inks using different types of resin and reaction initiator will be available and users can select materials according to their manufacturing equipment and application.
Solar cells including silicon and dye sensitized on thin-film flexible plastic substrates.
After printing a circuit on base material using this ink and exposing it to UV light for approximately 0.3 seconds, the user can instantly harden the printed film even at room temperature to form a circuit that carries a current. At a film thickness of five micrometers or more (one micrometer is one millionth of a meter), it is possible to form wiring on the same level as the conductive material generally used at present, with electrical resistivity of 10-3Ω/cm. By using this ink, it is possible to perform wiring not only on glass base material and substrates, but also flexible base material such as polyvinyl chloride film (PVC film) and polyester film (PET film) on which it was previously difficult to form electronic circuits due to their susceptibility to heat.
From January 2012 samples are available for solar cell manufacturers, display manufacturers and printer manufacturers.