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Copper laser patterning on a flexible substrate using a cost-effective 3D printer
Sajal Chakraborty1, Ho-Yeol Park1, Sung Il Ahn2
1Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National University, Busandaehakro 63-2, Busan, 46241, Republic of Korea.
Scientific Reports
|December 8, 2022
Summary
Direct laser patterning of copper on polyimide using a 3D printer achieved cost-effective, defect-free patterns. Optimized focal length and scan gaps enhance conductivity and adhesion for flexible bioelectronics applications.
Area of Science:
- Materials Science
- Additive Manufacturing
- Surface Engineering
Background:
- Direct laser patterning offers a promising route for fabricating conductive microstructures.
- Cost-effective methods are crucial for scaling up advanced materials processing.
- Polyimide substrates are widely used in flexible electronics due to their thermal and mechanical properties.
Purpose of the Study:
- To investigate cost-effective direct laser patterning of copper (Cu) on thin polyimide (PI) substrates.
- To optimize laser process parameters, specifically focal length and scan gap, for improved Cu pattern quality and conductivity.
- To evaluate the performance of patterned Cu for bioelectronic applications.
Main Methods:
- Utilized a 405 nm laser module attached to an inexpensive 3D printer for direct laser patterning of Cu on PI (12.5-50 µm thickness).
- Controlled laser focal length (shorter focal length - SFL, longer focal length - LFL) and scan gaps to minimize defects and surface damage.
- Assessed Cu pattern resistivity, sheet resistance, and adhesion after cleaning, and demonstrated functionality in a wearable bioelectronic setup.
Main Results:
- Achieved clean Cu line patterns without defects by controlling focal length (SFL: -2.4 mm, LFL: 3 mm relative to actual focal length).
- Shorter focal length (SFL) resulted in lower resistivity (48 μΩ·cm) after one scan, while longer focal length (LFL) showed lower resistivity (70 μΩ·cm) after multiple scans.
- Cu patterns fabricated with a 70 µm scan gap exhibited the lowest sheet resistance (4-4.4 Ω/ϒ) and improved adhesion after cleaning.
- Demonstrated successful application in bioelectronics, with LEDs functioning on flexible PI substrates attached to skin, even under bending.
Conclusions:
- Direct laser patterning with optimized focal length and scan gaps provides a cost-effective method for high-quality copper conductive patterns on polyimide.
- The process enables the fabrication of robust and conductive patterns suitable for flexible electronics and wearable bioelectronic devices.
- This technique offers a scalable and efficient approach for producing functional conductive elements for emerging technologies.
