Studies of Inkjet Printing Technology with Focus on Electronic Materials

Abstract

Printed electronics (PE) is based on printing thin- and thick-film structures on cost-sensitive flexible substrates, such as paper-like, plastic, and on rigid substrates using a novel approach to manufacturing electronics which also enables two- or threedimensional printing. Unlike conventional electronic manufacturing, i.e., subtractive photolithography techniques, PE is an additive processing method, whereby the functional material is deposited in a controlled manner to print the desired pattern without wasting the material. Electronics can be printed using several methods, e.g., screen printing, flexography, gravure printing, offset lithography, nano-imprint, and inkjet printing. There are several advantages to using the above methods. For example, freedom of substrate use facilitates the development of novel products. The low amount of material waste, low investment in production facilities, the versatility of the printing system, and many other benefits make PE ideal for low-cost electronics production. In addition, the data-driven nature of digital printing manufacturing methods allows fast manufacturing runs and a short time cycle from design to manufacturing, which all translate into shorter delivery times in manufacturing. Inkjet printing technology is currently in a phase of proving its technological viability in the low-cost and high-volume manufacture of electronics. However, in technology development such change is only possible by demonstrating the reliability, durability, and applicability of the existing or novel electronic applications. In this work, inkjet printing technology was studied from the viewpoint of materials science and its potential to integrate electronic applications. The basic research concentrated on defining ink and substrate materials, their interactions, and on processing the materials with R&D/pilot line inkjet printers which all are commercially available in the technology. The applied research focused on electronic component manufacture, on selectively applying existing conventional or novel functional materials, and on defining viable material alternatives. The technology development consisted of evaluating printed structures and their materials in terms of environmental and mechanical reliability.