Reliability of Additively Printed Traces on Polymer Substrates Subjected to Mechanical Stretching

Abstract

Stretchable Electronics are rapidly emerging and making their way into the novel electronic devices attracting with their application in healthcare and wearable technologies. They provide superior characteristics over the conventional rigid and flexible materials. For the last decade, much work has been done in developing and improving the electronics that can fold, stretch, and even bend. In addition, the ability to additively print interconnects or traces on a stretchable material offers numerous possibilities that can never be achieved by rigid and flexible electronics. As we dive into the world of stretchable and conformable electronics, new challenges that come with stretchable materials need to be addressed, such as in manufacturing, their operational temperature, electrical and mechanical properties. Biggest of them would be their reliability in sustaining the properties even when it is deformed or stretched. Many research groups have worked on the stretchable materials and come up with interesting results. In this study, we utilize the additively screen-printed interconnects on a stretchable polymer substrate subjected to mechanical stretching. The polymer is a type of polyurethane that have excellent stretchability and temperature that can sustain the curing temperature of the ink printed. The ink used in this study is stretchable silver paste that has excellent adhesion, conduction properties, and compatible with the polyurethane substrate used in this study and multiple synthetic fibers. The effect of the amount of stretching imposed on a stretchable substrate on their electrical properties has not been looked at yet. The experiment process involves mechanically stretching the screen-printed substrate, characterizing the stretchable interconnects with their initial resistance, following with the insitu measurement of resistance while mechanically stretching, analyze the change in resistance against the strain level imposed. The effect on resistance while stretching versus the amount of stretch imposed is quantified. The challenges faced during the manufacturing process of screen-printed stretchable interconnects on a polymer substrate is discussed and the resistance data while subjected to stretching is presented in this paper.