Conductive Substrate Manufacturing Suppressing Intersection Growing
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Solution Overview
Problem
The existing methods for manufacturing conductive substrates with conductive thin wires suffer from intersection growing, resulting in thicker line widths and reduced conductivity at intersection portions, which necessitates the development of a method to suppress intersection growing and achieve thinner line widths with excellent conductivity.
Innovation Solution
A manufacturing method for a conductive substrate involves forming a mesh-shaped underlying silver pattern on a base material using a photographic method, disposing a resist film, exposing it from the side opposite to the underlying silver pattern, developing the resist film to form a resist pattern, and performing a plating treatment using the underlying silver pattern as a seed layer to form a metal pattern, thereby obtaining a conductive thin wire with a thin line width and suppressed intersection growing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plating resist pattern is formed using a negative tone photoresist, then the conductive thin wire can be formed, but intersection growing occurs resulting in thicker line width at intersection portions
Solution Approach 1:
The patent applies positive tone photoresist instead of negative tone photoresist, inverting the development logic. In positive tone photoresist, the exposed portions are removed during development, allowing precise control of the opening portions without the intersection growing problem that occurs with negative tone photoresist where unexposed portions remain and cause thickening at intersections.
Solution Approach 2:
The patent changes the parameter of photoresist type from negative tone to positive tone, which fundamentally alters the development behavior. This parameter change enables precise line width control by ensuring that only the exposed areas (corresponding to the desired wire pattern) are removed, preventing the unwanted material accumulation at intersection points that characterizes negative tone photoresist processing.
2Reliability
If the line width of the conductive thin wire is reduced, then the conductivity is improved, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
By inverting to positive tone photoresist, the patent achieves better control over thin line widths. The exposure and development process with positive tone photoresist provides sharper edges and more consistent line widths, even at reduced dimensions, because the removal of exposed material creates cleaner boundaries compared to the retention of unexposed material in negative tone systems.
Solution Approach 2:
The patent ensures uniform exposure conditions across the entire pattern area, creating consistent local quality throughout. This uniformity in the photoresist processing ensures that thin wire sections and intersection portions are treated equally, maintaining precise line width control and consistent conductivity across the entire conductive substrate.
3Illumination intensity
If the line width of the conductive thin wire is made thin, then the visibility is improved, but the intersection growing becomes more pronounced
Solution Approach 1:
The use of positive tone photoresist inverts the material removal logic, ensuring that thin wire portions are precisely defined by the exposure pattern without the intersection growing artifact. This inversion allows the wire to maintain its intended thin profile throughout, including at intersection portions, thereby preserving both visibility and geometric accuracy.
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
The method effectively manufactures conductive substrates with conductive thin wires that have a thin line width, excellent conductivity, and suppressed intersection growing, enhancing the performance and visibility of the conductive substrates in applications such as touch panels.
Implementation Method 1
a step of forming a mesh-shaped underlying silver pattern on a side of one surface of a base material by a photographic method
Implementation Method 2
a step of exposing the resist film by irradiation of light from a side of a surface of the base material on which the underlying silver pattern is not formed
Implementation Method 3
a step of performing a plating treatment using the underlying silver pattern as a seed layer to form a metal pattern on the underlying silver pattern
Data Source
AI summary
A manufacturing method for a conductive substrate having a conductive thin wire with a thin line width and excellent conductivity in which the intersection growing is suppressed. The manufacturing method includes a step of forming a mesh-shaped underlying silver pattern on a side of one surface of a base material by a photographic method, a step of disposing a resist film on the side of the surface of the base material on which the underlying silver pattern is formed, a step of exposing the resist film by irradiation of light from a side of a surface of the base material on which the underlying silver pattern is not formed, a step of developing the exposed resist film to form a resist pattern, and a step of performing a plating treatment using the underlying silver pattern as a seed layer to form a metal pattern on the underlying silver pattern.