Application 54 - Nozzle-Free Inkjet Technology

Abstract

Inkjet technology was developed as a new printing method, and due to the rapid proliferation of the computer, it has been widely used in low-cost, small-sized printing units such as printers or copying machines for domestic use. The inkjet printing method is classified into two categories. One method uses a piezoelectric device that gets deformed when a voltage is applied to it. The other is the thermal or the bubble jet method that utilizes the generation of air bubbles due to heating. Both methods require very fine nozzles. The ink is pushed out from the nozzle for printing due to the deformation of the piezoelectric device in the piezoelectric method and due to the pressure of an air bubble created inside the ink by heating in the thermal or the bubble jet method. Therefore, the ink needs to have properties suitable for the nozzle such as high fluidity, low viscosity, and appropriate drying property, and a cleaning system is always provided for clearing clogged ink. In addition, this inkjet technology is not merely used in printing machines but is also being used for the manufacture of devices such as multilayer printed circuit boards, displays, or DNA chips, etc., and for accurate injection of very small quantities of materials for quantitative analysis. In these new applications, unlike the dye-based inks used conventionally, the inks containing organic materials as well as those dispersed with organic, inorganic, and metallic fine particles (nanoparticles) are used. In the latter case, it is used as the liquid raw materials for device manufacture. To widen the applicability of inkjet technology from simple printing to new applications, improvements in the technology and formulation of the target inks become very important. However, to prepare the samples of a device, inclusion of organic materials or dispersion of particles is necessary, which causes problems such as reduction in the fluidity or increase in the viscosity of the ink (the solution of the raw materials) as well as wearing out or clogging of the nozzles. Therefore, to widen the applicability of inkjet technology it is necessary to widen its technical applicability to solutions of different raw materials. For the purpose of solving such problems caused by nozzles, nozzle-free inkjet technology and a system using it were jointly developed by the Joining and Welding Research Institute of Osaka University and Hosokawa Powder Technology Research Institute. In this chapter, an introduction is given about the principle of nozzle-free inkjet technology, an outline of the development system, and some samples of their application.