Silver nanoparticle inks are increasingly applied for the manufacture of inkjet-printed electrically conductive patterns. In order to obtain high conductivity, the printed liquid patterns have to be functionalized by an appropriate post- treatment step. Modern post-treatment methods using e.g. microwaves, intense pulsed light or adopted infrared radiation, are nevertheless the basis of the thermal process. The thermal treatment e.g. in furnaces or on heating plates, is applicable for a great variety of inks and ensures an efficient sintering without major technical efforts. It has been studied intensively wherein the reports mainly focus on reduction of the resistivity by controlling the parameters of the thermal treatment. Our researches exceed these comparative studies by investigating multi-layered patterns, their manufacturing and post-treatment.
Two silver nanoparticle inks were inkjet printed on a rigid and a flexible substrate. The geometry of the patterns was varied. The different drying behaviors of the inks were investigated. In addition, the number of layers which were printed on top of each other was varied. The sintering temperatures and time durations were varied.
The morphology of the patterns is investigated by profilometry and optical microscopy. The microstructure is analyzed by scanning electron microscope and X-ray diffraction. Furthermore, the electrical characteristics were determined by the measurement of the resistance. The results indicate the relation between the manufacture and the resulting microstructure and functionality of the patterns. The knowledge of these parameters enables us to control the industrial manufacturing of similar conductive patterns.