HORIBA has successfully implemented in-line, non-destructive, non-intrusive and non-contact material analysis and characterisation techniques into roll-to-roll printed electronics manufacturing to provide quality assurance and improve yield.
Specifically, HORIBA provided the European SMARTRONICS project [FP7-NMP.2012.1.4.1] – an objective of which is the development of smart nanomaterials for organic electronics – with in-line spectral ellipsometry and in-line Raman spectroscopy, both of which are fast and reproduceable techniques that do not require sample preparation. Additional characterisation and analysis techniques are also available.
Spectroscopic ellipsometry is a surface sensitive optical technique for thin and transparent layer characterisation. Properties that can be determined include layer thickness, surface roughness thickness, interface thickness, optical constants, film composition, optical band gap, crystallinity, grading and uniformity by depth and area. As for Raman spectroscopy, it combines the scattering of monochromatic light with vibration-induced molecular excitations, creating a shift in photon energy that provides essential information about the composition of a target material.
Jean-Paul Gaston, product manager of HORIBA Scientific, comments: “The spectroscopic ellipsometry and Raman spectroscopy techniques have their roots in the scientific community, and instrumentation for both is typically found in most laboratories. We have successfully adapted and implemented both for use in the roll-to-roll manufacture of printed electronics.”
Gaston goes on the explain that roll-to-roll is growing in popularity at an extremely healthy rate, thanks to the ability to process large area flexible materials when manufacturing photovoltaic cells, organic LEDs (OLEDs) and TV screens. “The economy of scale is very attractive because of the speed at which the manufacturing equipment can operate. However, quality assurance now depends on in-line, at-speed and non-intrusive material characterisation as no-one wants to end up with sub-standard batches of what is essentially a high-value product.”
Other material characterisation and analysis techniques HORIBA has made available for the manufacture of printed electronics include hyperspectral imaging (ideal for detecting post-coating defects), optical spectroscopy (where the absorption, emission, luminescence and/or scattering of light provide a unique fingerprint of a material) and energy dispersive x-ray fluorescence (ED-XRF, for the detection of defects, controlling and maintaining film thickness, and controlling the concentration of elements in the coating process).