Title: Fabrication of submicron-sized metal patterns on a flexible polymer substrate by femtosecond laser sintering of metal nanoparticles

Authors: Yong Son; Junyeob Yeo; Cheol Woo Ha; Sukjoon Hong; Seung Hwan Ko; Dong-Yol Yang

Addresses: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea ' Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea ' Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea ' Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea ' Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea ' Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Science Town, Daejeon 305-701, Korea

Abstract: The femtosecond laser sintering of metal nanoparticles was studied in order to fabricate submicron-sized metal patterns on flexible polymer substrates for various applications in the electronic and photonic industries. In this process, a mode-locked Ti:sapphire laser beam was tightly focused on silver nanoparticles. To achieve a homogeneous dispersion of the silver nanoparticles, the nanoparticles were prepared using a two-phase reduction method wherein the silver nanoparticles were encapsulated by functional surfactants. The key advantage of the femtosecond laser sintering process is that it reduces the heat-affected zone during sintering, as the femtosecond (10-15 s) laser pulse is shorter than the heat diffusion time (picosecond: 10-12 s). Therefore, sintering of metal nanoparticles is limited to the laser focal spot and the thermal diffusion effect is suppressed, enabling the realisation of submicron-sized metal patterns on flexible polymer substrates. Through this process, metal conductors with submicron-sized features and high conductivity were successfully fabricated. As demonstrated by the obtained results, the femtosecond laser sintering of metal nanoparticles is a process that offers direct, low-temperature, ultra-high-resolution results, and which will have numerous further applications in flexible electronics.

Keywords: femtosecond laser sintering; metal nanoparticles; submicron-sized patterns; flexible substrate; flexible electronics; nanotechnology; polymer substrates; photonics; silver nanoparticles.

DOI: 10.1504/IJNM.2013.057586

International Journal of Nanomanufacturing, 2013 Vol.9 No.5/6, pp.468 - 476

Received: 02 Dec 2012
Accepted: 16 Feb 2013
Published online: 31 Mar 2014 *

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