Dynamic bending test analysis of inkjet-printed conductors on flexible substrates

Abstract

The need to optimize space in electronic devices has made flexible electronics an attractive option for manufacturing electronics. Techniques to fabricate flexible circuits have become more and more common and the processes increasingly more efficient. Printed electronics is a potential technique for manufacturing electronic patterns on flexible substrates. In particular, inkjet printing is an effective way to produce fine, thin, conductive structures without touching the substrate material. This study concentrated on dynamic bending analysis of inkjet-printed silver conductors on a polymer substrate. Because printed electronics is a relatively new manufacturing method, not much research is yet available on mechanical endurance of printed structures. By default, thin layers of inkjet-printed traces may just prove to have good tolerance against bending. However, factors such as adhesion between ink layer and substrate and the effect of the porous structure of sintered nanoparticle ink must be studied. This paper evaluates the capability of the inkjet technique on a flexible substrate and benchmarks the results on conventional flexible copper circuit boards. Measurements were made in real time of the resistance of conductors while bending the sample along two different radii. Results showed that printed conductors were superior in endurance over etched copper circuits.

A Hybrid Low Power Biopatch for Body Surface Potential Measurement

“…A 'bending machine' is applied in this dynamic bending test. The measurement results show that inkjet-printed traces prove to have good tolerance against bending, in addition, the durability and reliability of the inkjet printed silver traces are much better than their counterpart: etched copper samples [29].…”

“…A dynamic bending analysis of the inkjet-printed silver conductors on a polymer substrate is recently reported in [29], where the reliability and durability issues of the printed metal traces on flexible substrates are investigated. A 'bending machine' is applied in this dynamic bending test.…”

“…PI substrate is selected as the patch carrier, since it is low-cost, flexible (wearable), printable, thin and light [9]. High resolution inkjet printing is utilized to fabricate the printed devices [10].…”

Inkjet printing in manufacturing of stretchable interconnects

“…When compared to conventional manufacturing methods of flexible circuits, inkjet printing involves fewer process steps and due to digital control of printing process, it is also more versatile than etching processes. Inkjet-printed conductors are typically thinner than conventional copper foils and have a somewhat porous structure, which have been shown to significantly improve performance in bending tests [10]. In addition, flexible circuit board manufactured with inkjet technology has been shown to be capable of replacing an existing flexible circuit board manufactured with conventional methods for example in a mobile phone [11,12].…”

Development of hybrid process for double-side flexible printed circuit boards using roll-to-roll gravure printing, via-hole printing, and electroless plating

“…The bending cycles had radii of 5 and 12 mm on the near coil pattern and via hole, respectively. The number of cycles was determined depending on the final product [32][33][34][35][36]. In this case, up to 400,000 cycles were performed to confirm the mechanical stability of the FPCB.…”