Research On Conductive Nanoink For Flexible Printed Electronics And Its Application

Printed electronics is an additive manufacturing technology with advantages such as substrate-unlimited,digitally-produced,low-cost,environmentally-friendly,and so on.Hence,it has been a research hot-spot in the past decade.With the development of wearable electronics and the Internet of Things,flexible printed electronics has become the most important field among printed electronics.At present,the research work mainly focuses on suitable ink materials,effective sintering methods and applications.Based on the above issues,a series of research work has been carried out.The purpose is to further improve the performance of printed tracks and explore the application of flexible printed electronics based on our previous research work.It mainly includes research of effective sintering method,preparation of small-sized nanoparticle ink,research of mixed conductive inks,and fabrication of flexible electronic devices.First,a white LED-assisted low-temperature sintering method was proposed and analyzed for large-size silver nanoparticles conductive ink.This sintering method was compared with the thermal sintering method.It turned out that the sintering effect was equivalent to thermal sintering at a high temperature without damaging the substrate,and the conductivity was raised to 4.7% of the bulk silver material.Then,a small-sized silver nanosphere ink was investigated based on the consideration of decrease in melting point under the “small size” effect.The polymer capping agent was investigated to control the size.The nanospheres with uniform size of 20-30 nm were obtained.Corresponding ink was prepared.Since there were lacunae among the nanospheres,the conductivity after sintering was only 2.87% of the bulk silver material.After that,in order to make the conductive ink form more complex interconnection networks,nanoplates were added.Silver nanoplates with size of ~70 nm were synthesized.Mixed ink containing silver nanospheres and nanoplates was obtained.The conductivity was5.52% before sintering and was improved to 14.28% after sintering.Through a series of comparisons,it was found that the performance of the single-morph nanoparticle ink was different with different types of mixed ink in terms of conductivity,bending stability and adhesion to the substrate.Lastly,the application in communication devices was explored.The design,simulation and fabrication of the passive components were conducted.A capacitive switch control circuit was also designed and manufactured.Besides,details during the manufacturing process that are more suitable for paper electronics or even flexible electronics,were also explored and optimized.