A thermal investigation on conductive silver ink tracks cured on flexible substrates by repeating irradiations of Nd:YAG laser at the wavelength of 532 nm

Abstract

The development of the plastic electronics industry has drawn great interest and inspired technology innovations in a broad area. This has stimulated the rapid development of flexible circuitry manufacturing technologies, including advances in conductive inks, printing technology and most importantly the novel curing technology-laser based curing (or Laser Direct Write). This has the ability to replace the conventional environmentally damaging and time consuming chemical etching method in current Printed Circuit Board (PCB) manufacturing. This work presented in this paper is an investigation into the Nd:YAG laser curing process at the wavelength of 532 nm of particulate silver inks. A mathematical approximation of key physical properties has been developed based on the presented experimental research for use in a finite element model (FEM) simulation. 532 nm has shown benefits in protecting the flexible substrate used from thermal damage, owing to the high transparency of the wavelength through the substrate material. In this paper, liquid-phase particulate silver ink tracks deposited on flexible substrates were irradiated by laser along the track geometry. Repetition of the laser beam scanning was found to produce a smooth and fully cured sample and further reduced the track's electrical resistivity.

Development of Online Tool Wear-Out Detection System Using Silver–Polyester Thick Film Sensor for Low-Duty Cycle Machining Operations

“…The maximum service temperature for the polymer substrate is 150 °C (423 K). Assuming thermal conductivity to be a constant 406 W/mK, the Lorenz number is 2.32 × 10 −8 [ 34 ], and the σtracing will be 4.1 × 10 7 /Wm. It was observed that the electrical conductivity of the silver tracing was not severely affected at the maximum service temperature.…”

Investigation of DLP Projector as an Energy Light Source to Cure Silver Conductive Ink

“…These processes use heat to evaporate binders and unwanted solvent in conductive ink polymers leaving only the metallic content on the substrate that is already been hardened and sticks onto the substrate. The conventional curing methods have their own weaknesses which laser irradiation process is a costly process [4] and silver conductive ink cured with conventional oven might undergo a warping defect [5]. Thus, there is a need to explore the possibility of using DLP projector as it was proven before that DLP projector had succesfully polymerised a photopolymer materials [6].…”

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