| Flexible printed circuit boards continue to be a high-growth technology in the area of electrical interconnectivity. Over traditional rigid printed circuit boards (PCB's), wire and wire harnesses, flexible circuit boards provide considerable weight, space, and cost savings This study investigates using conductive inks for printing circuits onto flexible nonwoven substrates as a low-cost alternative to traditional PCB manufacturing, because the emerging generation of nonwovens can offer wearability, printability, lightweight, durability and washability.; In this study, instead of incorporating conductive paths by weaving or knitting conductive yarns into the structure of the fabrics, conductive inks are used to print directly onto nonwovens by using polymer thick film technology. There are challenges in printing on fabrics such as achieving printing resolution and durability. The new generation of durable micro-fiber nonwoven fabrics offers the opportunity to "engineer" the structure surface properties, the network geometry and the capillary structure to optimize their use for printing. As in other fabrics, the ink substrate interaction determines the printability on nonwoven fabrics. In the case of nonwovens, the main parameters affecting the printability are surface energy of the fibers, fabric structure, fiber size and ink viscosity.; The first chapter outlines and examines existing technologies in the so-called electronic textiles area. The second chapter focuses on printing conductive inks on different nonwoven substrates. The polymer thick film conductive inks and the printed transmission lines will be characterized to demonstrate the properties of the structures used as substrates for flexible electronics. The performance metrics related to the circuits parameters and the manner in which the ink is distributed onto and into the substrate will be examined. The third chapter mainly focuses on the electrical conductivity and wash durability of the printed circuits. A method to control the durability of the printed circuits will be explored. In the last chapter, the interaction of liquids with different substrates using ink jet printing will be modeled and discussed. The modeling results of droplet substrate interaction will be presented for some topical geometries. |
