Electromechanical Properties Of Flexible Circuits Printed With Multiscale Nanoparticle Silver Ink

Flexible electronics is an emerging electronic technology.The use of silver nanoparticle conductive ink to print conductive patterns on flexible substrates has great application potential in flexible electronic devices.In order to ensure the stability of flexible electronic devices during use,flexible electronic interconnects need to have good electrical conductivity,bending deformation resistance and fatigue resistance.Based on the preparation of silver wires by multi-scale nanoparticle conductive ink printing,this paper studies the influence of the microstructure of printed silver wires on its electromechanical properties by using different sintering processes,and reveals the influence of porosity and particle size distribution law of multi-scale silver nanoparticle ink printing flexible silver wires on its conductivity,bending resistance and fatigue life.This paper is of great significance to improve the force,electrical comprehensive performance of printing flexible silver wires and promote the marketization of flexible electronics.The specific research content and results are as follows:(1)Preparation and research of multi-scale silver nanoparticle conductive ink printing flexible silver wires with different particle size distribution rules.Multi-scale silver nanoparticle conductive ink was prepared by microwave "one-step method",and the influence of silver nitrate and polyvinylpyrrolidone on the particle size distribution of silver ink was studied during the preparation process.Combined with the scanning electron microscope diagram,and the grain size statistics software was used to make detailed statistics on the particle size distribution of each ink,it was found that the size variance of the size of the ink sample with a large average particle size was also large.Finally,the printing silver wire is prepared by using a direct writing printing device and a high-precision micro-nano deposition inkjet printing system.(2)The effect of sintering process on the mechanical and electrical properties of printed flexible silver wires was studied.The effects of current sintering,intense pulsed light sintering and hot-pressing sintering on the microstructure and electrical properties of multi-scale silver nanoparticle conductive ink printing silver wire under different sintering parameters were studied.The results show that although sintering based on the current Joule thermal effect can improve the conductivity of the wire,because it can only form a local sintering effect,the microstructure is uneven,which is not conducive to the application of productization.However,the influence mechanism of intense pulsed light sintering and hot-pressing sintering on the microstructure of the sample is different,but the sintered sample has a denser microstructure and lower resistivity.At the same time,the mechanical test platform built by self-designed is used to perform bending tests on each sample.In the bending deformation test,the maximum resistance changes rate and the resistance increase rate before and after bending of the hot press sintered sample are smaller,while the sample after intense pulsed light sintering has a more stable performance in terms of bending fatigue resistance.(3)The influence of particle size distribution on the mechanical and electrical properties of printed flexible silver wires was studied.Electrical properties,single bending and cyclic bending tests were carried out on five multi-scale nano-silver ink printed silver wires with different particle size distribution rules.Printed silver wire specimens with a larger particle size distribution have lower porosity and resistivity after hot press sintering.However,silver wires with large average particle size and standard deviation of particle size have a large thickness and large pores after sintering,which will produce greater stress or strain during the bending process,which is not conducive to improving the mechanical reliability of the sample.In addition,silver wires with small average particle size and standard deviation of particle size may reduce the bonding force between particles due to their higher porosity,thereby reducing their resistance to bending deformation.Finally,the influence of particle size distribution of printed silver wire on its microstructure and mechanical properties was studied by finite element simulation.