Transfer Film Surface Roughness Control for Touch Panel Lamination
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Solution Overview
Problem
Current methods for forming transparent insulating layers or protective films on capacitance-type touch panels face issues such as resist component leakage, air bubble intermixing during lamination, and visibility of transparent electrode patterns, leading to reduced production efficiency and poor visibility.
Innovation Solution
A transfer film comprising a temporary support, a transparent resin layer, and a cover film, where the cover film's surface roughness is controlled to inhibit air bubble formation and enhance lamination quality, allowing for the formation of a laminate that withstands moist heat tests and improves pattern visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a transparent insulating layer or protective film is formed by coating on a substrate with opening portions that have undergone reinforcing treatment, then the film can be applied to the substrate, but resist components leak or stick out of the opening portions, requiring additional removal steps and reducing production efficiency
Solution Approach 1:
The transfer film is prepared in advance with the resist pattern already formed on its surface. This preliminary formation of the resist pattern eliminates the need for subsequent resist removal steps after coating, as the pattern is transferred intact to the substrate during the coating process itself.
Solution Approach 2:
A transfer film serves as an intermediary carrier that holds the resist pattern and transfers it to the substrate during coating. This intermediary approach allows the resist pattern to be formed without direct contact with the substrate, preventing resist leakage into opening portions while maintaining ease of manufacture.
2Ease of manufacture
If coating methods are used to form transparent insulating layers or protective films, then the films can be applied to substrates, but air bubbles mix during lamination and poor quality laminates are produced
Solution Approach 1:
The coating method is replaced with a lamination process where the transfer film is mechanically bonded to the substrate. This substitution eliminates air bubble formation that occurs during coating, as the lamination process allows for better bubble removal and ensures high-quality laminates without the defects associated with coating methods.
3Ease of manufacture
If transparent electrode patterns are formed on substrates, then capacitance-type input devices can be manufactured, but the patterns become noticeable and visibility is reduced
Solution Approach 1:
A transparent resin layer is applied specifically to the transparent electrode patterns to modify their optical properties locally. This local treatment reduces the visibility of the electrode patterns by adjusting their refractive index and surface characteristics, while leaving the rest of the substrate unchanged.
Solution Approach 2:
The refractive index and surface properties of the transparent electrode patterns are changed by applying the transparent resin layer. This parameter change makes the electrode patterns less visible by matching their optical characteristics with the surrounding areas, improving overall visibility while maintaining ease of electrode formation.
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 solution effectively prevents air bubble intermixing during lamination, enhances the visibility of transparent electrode patterns, and improves the production efficiency of capacitance-type input devices and image display devices by using a transfer film with specific surface roughness and refractive index adjustments.
Implementation Method 1
when the cover film is peeled from the resin layer, a surface of the cover film that contacted the resin layer has surface roughnesses SRz and SRa of equal to or less than 130 nm and equal to or less than 8 nm respectively
Implementation Method 2
by the effect of optical interference resulting from the respective layers, the transparent electrode pattern becomes a stealth pattern, and the tone thereof becomes neutral
Data Source
AI summary
The transfer film includes a temporary support, a resin layer, and a cover film in this order, in which when the cover film is peeled from the resin layer, a surface of the cover film that contacted the resin layer has surface roughnesses SRz and SRa of equal to or less than 130 nm and equal to or less than 8 nm respectively that are measured based on JIS-B0601-2001.