Rapid laser sintering of metal nano-particles inks

Abstract

Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

Contactless In Situ Electrical Characterization Method of Printed Electronic Devices with Terahertz Spectroscopy

“…We demonstrate that contactless dual-wavelength THz spectroscopy analysis, which requires only a single THz measurement, is more precise and repeatable than the conventional four-point probe conductivity measurement method. Our results open the door to a simple strategy for performing contactless quality control in real time of printed electronic devices at any stage of its production line.to the post-printing process [12]. Particularly, the solid and uniform dielectric or metallic tracks from the printed pattern are obtained during this step.The quality of PE devices can be evaluated using different types of microscopy, such as atomic force microscopy, scanning electron microscopy or optical microscopy [13,14], which are well-established tools for analyzing the surface morphology of materials.…”

“…Post-printing processes also play a key role in the manufacturing of PE devices. The most commonly used sintering approaches are conventional thermal annealing, electrical sintering, microwave, and photonic sintering by either continuous-wave laser irradiation or high-power flashing lamps [7,12]. While the spatial resolution and definition of the device are related to the printing method, the quality of the electrical properties of the printed devices is directly related…”

“…to the post-printing process [12]. Particularly, the solid and uniform dielectric or metallic tracks from the printed pattern are obtained during this step.…”

Localized Laser Sintering of Metal Nanoparticle Inks Printed with Aerosol Jet® Technology for Flexible Electronics

“…Promising results of laser sintering of metal nanoparticle inks have been reported by many authors, mostly with ink layers of thickness below one micron (i.e., <1,000 nm) [6][7][8][9][10][11]. Unlike inkjet printing which operates with larger droplets of low viscosity inks, the Aerosol Jet® printed lines can have a much higher aspect ratio (with layer thickness typically of several microns as printed in a single pass) because of the effective inflight solvent removal with microdroplets of appropriately formulated inks [12].…”

“…For the same area of line cross-section, which determines the line conductance, the Aerosol Jet® printed lines can be much narrower, enabling production of higher density electronic circuitry. Sintering high-aspect-ratio lines can pose technical challenges with respect to crack formation [9] and material delamination (because of high pressure gas pocket formation) [11].…”