Deposition of High Conductivity Low Silver Content Materials by Screen Printing

Eifion Jewell,David Gethin,Tim Claypole,Simon Hamblyn

doi:10.3390/coatings5020172

Abstract

A comprehensive experimental investigation has been carried out into the role of film thickness variation and silver material formulation on printing capability in the screen printing process. A full factorial experiment was carried out where two formulations of silver materials were printed through a range of screens to a polyester substrate under a set of standard conditions. The materials represented a novel low silver content (45%–49%) polymer material and traditional high silver content (65%–69%) paste. The resultant prints were characterised topologically and electrically. The study shows that more cost effective use of the silver in the ink was obtained with the low silver polymer materials, but that the electrical performance was more strongly affected by the mesh being used (and hence film thickness). Thus, while optimum silver use could be obtained using materials with a lower silver content, this came with the consequence of reduced process robustness.

Highlights

In total the silver ink market is estimated to be worth around $760 Million in 2012 [1]
The use of nano silver inks in inkjet and other printing processes is rising, thick film screen printing remains the dominant application technology in the market [5]
In order to investigate the relationship between formulation and film thickness a full factorial experimental design was employed where six silver materials were printed through 10 screens

Summary

Introduction

In total the silver ink market is estimated to be worth around $760 Million in 2012 [1]. During the material formulation process the balance between silver quantity, particle size (and structure) must be considered in order to provide the required conductivity while maintaining film integrity, adhesion, flexibility and process compatibility. The use of silver as a conductive material for device manufacture (PV, sensors and RFID) by screen printing is widely reported, few published studies have examined the interactions between macro material properties, mesh characteristics and printed feature quality, for systems which are cured at low temperature (

Experimental Section

Material Rheology

Polymer Inks

Paste Inks

Comparison of Each Set of Materials

Conclusions