Feasibility analysis for the application of conduction tracks on textiles by means of laser radiation

Abstract

AbstractTextiles are not only used for clothing but also have found applications in many other areas. Textiles fulfilling functional or technical properties are called “technical textiles.” Incorporation of conductive components, sensors, or materials reacting to environmental influences convert those into so-called “smart textiles.” Common methods of applying conductive tracks to textiles are embroidery, which can cause damage to the textile, or printing of a low-conductivity paste that may include toxic chemicals. A new method of applying electrical conductors to textiles for contacting is laser welding. In this process, a thin metal foil is welded on locally with an absorber placed above the metal foil to ensure that sufficient energy is applied to partially melt the textile underneath the metal foil. One variant for welding conductive tracks is the use of a globo-optics and a diode laser system with a wavelength of 975 nm. With these optics, the glass sphere focuses the laser beam and serves as a mechanical pressure tool for achieving a zero gap between fabric and foil. Parameters that are varied are the processing speed and the laser power receiving different track widths, as well as the type of textile. In this work, their influence is evaluated by microscopy, electrical resistance measurements during Martindale tests for abrasion resistance, and tensile tests. The investigations clarify the durability and utility of welded conductive tracks on textiles. It is possible to produce conductive tracks out of beaten copper joined on textiles using laser radiation showing conductivity after 10,000 abrasion cycles. The tensile strength of textiles totally made of thermoplastics is more influenced by the heat input of the laser than blended textiles, but their abrasion resistance is worse. Furthermore, an outlook on the possibility of welding using a laser source with a wavelength of 450 nm (blue laser) and a scanner as optics will be given.