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Title: Electrical resistance reduction induced with CO₂ laser single line scan of polyimide
Authors: Wang, Zhongke
Tan, Kok Keat
Lam, Yee Cheong
Keywords: Engineering::Mechanical engineering
Issue Date: 2021
Source: Wang, Z., Tan, K. K. & Lam, Y. C. (2021). Electrical resistance reduction induced with CO₂ laser single line scan of polyimide. Micromachines, 12(3), 227-.
Project: U12-M-007JL
Journal: Micromachines
Abstract: We conducted a laser parameter study on CO₂ laser induced electrical conductivity on a polyimide film. The induced electrical conductivity was found to occur dominantly at the center of the scanning line instead of uniformly across the whole line width. MicroRaman examination revealed that the conductivity was mainly a result of the multi-layers (4–5) of graphene structure induced at the laser irradiation line center. The graphene morphology at the line center appeared as thin wall porous structures together with nano level fiber structures. With sufficient energy dose per unit length and laser power, this surface modification for electrical conductivity was independent of laser pulse frequency but was instead determined by the average laser power. High electrical conductivity could be achieved by a single scan of laser beam at a sufficiently high-power level. To achieve high conductivity, it was not efficient nor effective to utilize a laser at low power but compensating it with a slower scanning speed or having multiple scans. The electrical resistance over a 10 mm scanned length decreased significantly from a few hundred Ohms to 30 Ohms when energy dose per unit length increased from 0.16 J/mm to 1.0 J/mm, i.e., the laser power increased from 5.0 W to 24 W with corresponding power density of 3.44 × 10 W/cm² to 16.54 W/cm² respectively at a speed of 12.5 mm/s for a single pass scan. In contrast, power below 5 W at speeds exceeding 22.5 mm/s resulted in a non-conductive open loop.
ISSN: 2072-666X
DOI: 10.3390/mi12030227
Schools: School of Mechanical and Aerospace Engineering 
Research Centres: Singapore Institute of Manufacturing Technology 
SIMTech-NTU Joint Laboratory 
Rights: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MAE Journal Articles

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