Methods for short-circuit risk evaluation and reduction in printed electronics based on a filled micro-channel

Abstract As one of the key challenges in high-resolution printed electronics, short-circuits are difficult to detect and eliminate in mass production. In this work, high-resolution circuits were fabricated by filling conductive ink into the micro-channels on glass substrates with SU-8 sidewalls. The value of satellite droplet area percentage, which was used as an index for short-circuit risk evaluation, was reduced by improving the contact angle and height of the sidewalls. The sample with a hydrophilic SU-8 sidewall is measured to short-circuit because of the silver ink connecting adjacent printed lines. In contrast, the typical satellite droplet area percentage value of the CF 4 plasma treated sample can be only 0.2% of the untreated one. On the other hand, the sample with the lowest sidewall height of 1.3 μ m has the minimum typical satellite droplet area percentage, which is only about 0.64% of the sample with the highest sidewall. Interestingly, the other samples with a variable range of sidewall heights have quite similar silver layer thickness values, while the optimized silver thickness was increased by more than 50% compared to these samples. A multi-channel capacitive-type sensor array was also used to print detect the short-circuit defects efficiently. These results revealed that it is possible to improve the short-circuit risk monitoring and reduction in high-resolution mass printed electronics in the future.