Ulvac Inc exhibited an ITO wiring formed on a glass substrate by inkjet printing at FPD International 2007. The glass substrate measures 100 x 100mm. The wiring width is 100μm.
"Although some manufacturers exhibited Ag or Au wirings formed by inkjet printing thus far, this is the first time that an ITO wiring made by this method is put on display," a demonstrator from Ulvac said.
The ITO ink was developed by Ulvac Materials Inc. The particle diameter of the material is small enough to reduce clogging. In addition, the material features a long life resulting from the high dispersibility of particles. The solvent used is decahydronaphthalene. The applied ink will turn from black to transparent when it is heated at 230°C under reduced pressure.
The product has a problem of high electric resistance. While the sheet resistance of ITO formed by sputtering is 50Ω/sq, that of ITO formed by inkjet printing reaches 400Ω/sq, which is one order of magnitude higher.