Ultrananrow-Gap Printing via Swelling Interlayer
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Solution Overview
Problem
Conventional printing methods struggle to produce narrow gaps between electrodes in printable electronic devices, such as RFID tags, due to uncontrolled ink spreading and the complexity and cost of photolithography, limiting the resolution and flexibility of pattern design.
Innovation Solution
A direct printing process using a substrate with a pre-coated interlayer, such as SU-8, where the ink contains a solvent that causes the interlayer to swell, creating embankments that confine the ink and prevent merging with adjacent lines, allowing for the printing of ultranarrow-gap lines without pre-patterning or high surface energy materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional printing methods are used to deposit ink on substrate, then material usage is improved, but manufacturing precision deteriorates due to uncontrolled ink spreading
Solution Approach 1:
The substrate is pre-coated with a swelling-sensitive interlayer material before ink deposition. This preliminary preparation enables the interlayer to respond to the ink solvent by swelling and forming embankments that confine the ink, thereby preventing uncontrolled spreading while maintaining material efficiency
Solution Approach 2:
The invention changes the physical state of the interlayer material through solvent-induced swelling. The interlayer transitions from a flat state to a swollen embankment structure upon contact with the ink solvent, dynamically adjusting the confinement parameters to control ink spreading and achieve precise gap dimensions
2Manufacturing precision
If photolithography process is used to achieve narrow gaps, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the photolithography process from the fabrication sequence by replacing it with a direct printing approach on swelling-sensitive interlayer. This removal simplifies the overall device fabrication process while maintaining the ability to achieve narrow gaps through the interlayer's swelling mechanism
Solution Approach 2:
The interlayer material performs the patterning function autonomously through solvent-induced swelling. The interlayer self-organizes into embankment structures that define the electrode gaps without requiring external photolithography equipment or complex process steps, enabling self-patterned narrow-gap structures
3Manufacturing precision
If photolithography process is used to achieve narrow gaps, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The interlayer is pre-coated on the substrate before ink deposition, preparing the surface to respond to the ink solvent. This preliminary setup enables rapid pattern formation through swelling, eliminating the time-consuming photolithography steps while maintaining precision gap control
Solution Approach 2:
The invention skips the multiple sequential steps of photolithography (photoresist coating, exposure, development, etching) by directly printing ink on the swelling-sensitive interlayer. The rapid solvent-induced swelling process rushes through the pattern formation step in a single action, significantly reducing fabrication time
4Manufacturing precision
If microcontact printing is used to pre-pattern ink barrier strips, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the microcontact printing step and the associated elastomeric stamp fabrication process. By using a swelling-sensitive interlayer, the pattern definition function is achieved through material response rather than mechanical stamping, simplifying the overall process
Solution Approach 2:
The swelling-sensitive interlayer acts as an intermediary between the printed ink and the final pattern structure. Instead of using an elastomeric stamp as an intermediary, the interlayer mediates the pattern formation through controlled swelling, creating embankments that define the electrode gaps with simpler process steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves high-resolution printing of ultranarrow-gap lines with gaps smaller than 10 µm, enabling the fabrication of high-performance transistors and other electronic devices without lithography, improving resolution and reducing costs by controlling ink spreading and eliminating the need for photolithography.
Implementation Method 1
the ink comprising the functional material and a solvent that swells the interlayer to cause the interlayer to bulge at edges of the ink
Data Source
Figure 1A~1D
Figure 2
Figure 3a~3d
AI summary
Disclosed is a method of printing ultranarrow-gap lines of a functional material, such as an electrically conductive silver ink. The method entails providing a substrate having an interlayer coated on the substrate and printing the ultranarrow-gap lines by depositing ink on the interlayer of the substrate, the ink comprising the functional material and a solvent that swells the interlayer to cause the interlayer to bulge at edges of the ink to thereby define embankments that confine the ink.