In-situ tension investigation of additively manufactured silver lines on flexible substrates

The reliability of additively manufactured flexible electronics or so-called printed electronics is defined as mean time to failure under service conditions, which often involve mechanical loads. It is thus important to understand the mechanical behavior of the printed materials under such conditions to ensure their applicational reliability in, for example, sensors, biomedical devices, battery and storage, and flexible hybrid electronics. In this article, a testing protocol to examine the print quality of additively nanomanufactured electronics is presented. The print quality is assessed by both tensile and electrical resistivity responses during in-situ tension tests. A laser based additive nanomanufacturing method is used to print conductive silver lines on polyimide substrates, which is then tested in-situ under tension inside a scanning electron microscope (SEM). The surface morphology of the printed lines is continuously monitored via the SEM until failure. In addition, the real-time electrical resistance variations of the printed silver lines are measured in-situ with a multimeter during tensile tests conducted outside of the SEM. The protocol is shown to be effective in assessing print quality and aiding process tuning. Finally, it is revealed that samples appearing identical under the SEM can have significant different tendencies to delaminate.