Narrow Frame Touch Input Sheet Simultaneous Etching
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Solution Overview
Problem
Existing methods for manufacturing narrow frame touch input sheets face challenges in achieving precise alignment of metal films, leading to inconsistent resistance and reduced productivity, and require stacking of two touch input sheets, which decreases transmittance and increases thickness.
Innovation Solution
A method involving the simultaneous etching of transparent conductive films and light-excluding conductive electrode films on both surfaces of a single base sheet, with a first resist layer forming a fine wiring circuit pattern in the outer edge and exposing the transparent conductive film in the central window portion, allowing for precise alignment and high productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mask position is shifted during the formation of the second photoresist film, then the metal film thickness becomes inconsistent, but the resistance of the metal film cannot be controlled within the predetermined range
Solution Approach 1:
The patent divides the conductive film formation into two separate stages: first forming the transparent conductive film (ITO) with circuit patterns, then forming the metal film (indium) with terminal patterns. This segmentation allows each layer to be optimized independently, preventing thickness inconsistency issues that would arise from simultaneous formation with mask alignment problems.
Solution Approach 2:
The transparent conductive film is formed and patterned first, establishing the base circuit structure before the metal film is added. This preliminary action ensures that the underlying conductive pattern is already in place, so when the metal film is subsequently formed, any position shifts do not affect the overall alignment and thickness uniformity of the final conductive structure.
2Manufacturing precision
If two touch input sheets are stacked and glued together to form transparent conductive film patterns in X and Y directions, then alignment is achieved, but productivity is lowered and transmittance is decreased
Solution Approach 1:
The patent merges both X-direction and Y-direction transparent conductive film patterns into a single touch input sheet by forming intersecting circuit patterns on the same substrate. This eliminates the need to manufacture and assemble two separate sheets, thereby improving productivity while maintaining precise alignment through a single-layer formation process.
Solution Approach 2:
The single transparent base sheet serves multiple functions simultaneously: it provides the substrate for both X-direction and Y-direction conductive patterns, acts as the structural support, and maintains optical transparency. This multi-functionality eliminates the need for multiple separate components and assembly steps.
3Manufacturing precision
If two touch input sheets are stacked and glued together to form transparent conductive film patterns, then alignment is achieved, but the thickness of the transparent window portion is increased
Solution Approach 1:
The patent combines both sets of transparent conductive films into a single substrate structure, eliminating the need to stack two separate sheets. This merging approach maintains the precise alignment of X and Y direction patterns while reducing the overall thickness to that of a single base sheet, thereby improving optical transmittance.
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 approach enables the creation of a capacitive touch input sheet with a narrow frame, high transparency, and small thickness, while ensuring precise circuit patterns and improved electrical conductivity, enhancing the manufacturing efficiency and quality of the touch input sheet.
Implementation Method 1
exposing and developing the first resist layer
Implementation Method 2
etching the transparent conductive film and the light-excluding conductive electrode film simultaneously on both surfaces
Data Source
Figure 1~2(c)
Figure 2(d)~4(a)
Figure 4(b)~4(e)
AI summary
Provided are a narrow frame touch input sheet, manufacturing method of the same, and conductive sheet used in the narrow frame touch input sheet, which are suitable for a capacitive touch sensor having a narrow frame and two layers of transparent conductive film patterns. The method uses the conductive sheet including one or more transparent base sheets stacked into a layer, transparent conductive films, light-excluding conductive electrode films, and first resist layers, which are layered sequentially on the uppermost and lowermost surfaces thereof. The first resist layers are exposed simultaneously on the both surfaces, and after development, the transparent conductive films and the light-excluding conductive electrode films are simultaneously etched, the first resist layers are stripped away, then second resist layers are formed as coating on the both surfaces in an outer edge portion, so that the light-excluding conductive electrode films are etched only in the central window portions. Thus, circuit patterns of the transparent conductive films are exposed.