Chip Card Cover Layer Thickness and Smoothness Control
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Solution Overview
Problem
The production of chip cards with displays faces challenges in maintaining mechanical protection while adhering to the maximum permissible thickness specified by ISO standards, as display elements and flat batteries often exceed these limits, and existing methods struggle to achieve a smooth surface without noticeable edges or defects.
Innovation Solution
A method involving the application of a thick water-based paint layer followed by thin solvent-based layers, allowing for a thin cover layer to be built over the display area, ensuring mechanical protection and compliance with ISO thickness standards, while enabling high-quality optical information and a smooth surface without edges or bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick cover layer is applied to protect the display element, then mechanical protection is improved, but the overall thickness exceeds the maximum permissible value according to ISO standards
Solution Approach 1:
The patent applies parameter changes by using a multi-layer coating system with different material properties and thicknesses. The first intermediate layer has a thickness of 10-30 μm, the second intermediate layer has a thickness of 2-6 μm, and the final layer has a thickness of 2-6 μm. This distribution of thickness parameters across multiple layers provides adequate mechanical protection while keeping the total thickness below 60 μm, complying with ISO standards.
2Length of stationary object
If a thin cover layer is applied to meet ISO thickness standards, then compliance with maximum thickness is improved, but mechanical protection of the display element becomes insufficient
Solution Approach 1:
The patent employs composite materials by combining multiple coating layers with different functions. The first intermediate layer provides base protection and adhesion, the second intermediate layer enhances mechanical strength, and the final layer provides a smooth, defect-free surface. This composite structure achieves adequate mechanical protection with a total thickness below 60 μm, meeting ISO standards while protecting the display element.
3Illumination intensity
If a recess is created in the cover film to expose the display, then visibility of the display element is improved, but a noticeable edge appears around the display
Solution Approach 1:
The patent applies preliminary action by creating a window in the first intermediate layer before applying the subsequent layers. This allows the display element to be visible through the window while the later layers are deposited only in specific areas surrounding the display, avoiding the formation of noticeable edges or bumps. The sequential layering ensures a smooth surface transition.
4Loss of information
If alphanumeric information is applied directly to the intermediate structure, then information display capability is improved, but achieving good optical quality becomes demanding in terms of production technology
Solution Approach 1:
The patent applies segmentation by separating the information display function from the structural layers. The alphanumeric information is applied directly to the first intermediate layer in a window area, which is then covered by subsequent layers that are deposited only in specific surrounding areas. This segmentation allows information display while maintaining a smooth surface and simplifying the production process compared to applying information directly to the final surface.
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 allows for overall thicknesses below 60 μm, providing adequate mechanical protection and a smooth surface for the display element, while enabling high-quality optical information and compliance with ISO standards, thus addressing the challenge of maintaining mechanical protection within the specified thickness limits.
Implementation Method 1
a comparatively thick top layer of water-based paint is first applied to a carrier layer, resulting in a very thick, solvent-free base structure compared to the following layers, to which at least thin layers of solvent-based materials can then be applied without blocking occurring
Data Source
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AI summary
Disclosed is a method for producing a finishing layer containing a window (104) for a portable data storage medium, in particular a chip card, and the use of said method for producing a data storage medium. According to the invention, a transparent plastic-based support layer (28) is used and an opaque colour layer (30) is applied on said support layer in a screen printing process, wherein the colour layer (30) comprises a recess (32) having the dimensions of the window (104). A first layer (40) of a transparent primer is then screen printed onto the colour layer and a design colour layer (50) is then applied in an offset printing process onto said first layer. A second layer (60) of a transparent primer is applied in an offset printing process on top of the design colour layer (50) and a transparent finish (70) is finally applied onto said second layer (60).