Concurrent Dual-Side Touch Sensor Circuit Patterning
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Solution Overview
Problem
Existing methods for forming touch sensors with electrically conductive transparent films, such as ITO or tin oxide, face challenges in patterning accuracy and yield due to variations in sputtering conditions, and struggle to concurrently pattern both surfaces of a base film with different designs.
Innovation Solution
A method involving the formation of light-shielding metal layers and photosensitive resin layers on both surfaces of a UV-blocking base film, followed by ultraviolet light exposure through different pattern masks, development, and etching to create routed circuit patterns, with subsequent lamination and exposure of photosensitive conductive films to form electrode patterns connected to the routed circuits, ensuring high accuracy and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sputtering is used to form electrically-conductive transparent films, then the films can be formed with good electrical conductivity and transparency, but the film quality varies with sputtering conditions causing etching speed variations and patterning defects
Solution Approach 1:
The patent changes the material parameter from sputtered ITO/tin oxide to screen-printed silver paste, fundamentally altering the formation mechanism. This eliminates sensitivity to sputtering parameters (power, pressure, temperature, atmosphere) and provides consistent etching characteristics with silver paste that can be reliably patterned using screen printing and etching processes
Solution Approach 2:
The patent replaces the physical vapor deposition process (sputtering) with a screen printing process. This substitution eliminates the complex parameter control requirements of sputtering while achieving reliable film formation through a simpler, more controllable printing and etching mechanism
2Manufacturing precision
If conventional photolithography and wet-etching are used to pattern electrically-conductive transparent films, then patterns can be formed, but the process takes a long time and incurs high costs
Solution Approach 1:
The patent uses screen printing masks that can be reused multiple times, replacing the need for expensive and time-consuming photolithography masks and processing. The screen printing approach allows for faster, more cost-effective patterning while maintaining acceptable precision for touch sensor applications
Solution Approach 2:
The patent extracts and eliminates the photolithography step from the conventional process sequence. By using screen printing directly to form the conductive pattern, the complex multi-step photolithography process (resist coating, exposure, development, etching, resist removal) is replaced with a simpler screen printing and etching process that is faster and more cost-effective
3Productivity
If inkjet or silkscreen printing is used to form routed circuits on both surfaces, then electrically conductive patterns can be created, but concurrent processing of both surfaces and alignment cannot be achieved
Solution Approach 1:
The patent merges the routing and electrode formation processes into a single integrated process. By forming both the routed circuits and electrode patterns simultaneously through concurrent screen printing and etching on both surfaces, the method achieves both high productivity and precise alignment that would be difficult to obtain through sequential processing
Solution Approach 2:
The patent transitions from sequential single-sided processing to concurrent dual-sided processing, effectively utilizing the third dimension (time) by performing operations on both surfaces simultaneously. This dimensional change in the process approach enables both surfaces to be processed in parallel while maintaining alignment through the integrated nature of the screen printing and etching 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 enables concurrent formation of routed circuit patterns on both surfaces of a touch sensor with high accuracy, improving alignment and productivity, and forming transparent electrodes connected to the routed circuits.
Implementation Method 1
a base film having a UV-blocking function
Implementation Method 2
irradiating the first photosensitive resin layers on the light-shielding metal layers with ultraviolet light through different pattern masks over the two surfaces
Implementation Method 3
an electrically conductive layer containing an electrically conductive fiber such as a silver fiber
Data Source
AI summary
[Object] To provide a method for manufacturing a touch sensor capable of concurrently forming routed circuit patterns on both surfaces of a base film and capable of aligning the routed circuit patterns on the top and bottom surfaces with each other with high accuracy.[Solution] A method for manufacturing a touch sensor includes forming electrode patterns on both surfaces of a base film through concurrent light exposure on both surfaces and development using photosensitive electrically conductive films each including a support film, an electrically conductive layer disposed on the support film and containing an electrically conductive fiber, and a second photosensitive resin layer disposed on the electrically conductive layer. Routed circuit patterns obtained by patterning the light-shielding metal layers are formed in advance on both surfaces of the base film.