UV-Cured Dual-Layer Coating for Fingerprint Sensor Surface Durability
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Solution Overview
Problem
Existing methods for manufacturing fingerprint sensors, such as painting and heat-transfer methods, face limitations including color implementation constraints, durability issues, and high production costs, leading to low yield and potential sensor malfunctions due to defects like cracks and pinholes.
Innovation Solution
An electronic device with a fingerprint sensor featuring a surface coated with an epoxy molding compound (EMC) resin, a UV bonding layer, and a UV coating layer, where the UV bonding layer and UV coating layer are sequentially stacked on the sensing surface without a separate heating process, enhancing durability and appearance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If painting method is used to coat the sensing surface, then color implementation is achieved, but the surface durability and hardness are limited and cracks may occur
Solution Approach 1:
The patent uses a composite coating structure consisting of a base coating layer and a UV-curable clear coating layer applied on top. This composite structure combines the color implementation capability of the base layer with the durability and crack resistance provided by the UV-curable clear coating layer, resolving the contradiction between color implementation and surface durability.
Solution Approach 2:
The patent changes the coating process parameters by introducing UV curing instead of traditional painting methods. The UV-curable clear coating layer is applied in a liquid state and then cured through UV irradiation, transforming the material state from liquid to solid to enhance surface hardness and durability while maintaining color implementation through the base coating layer.
2Ease of manufacture
If heat-transfer method is used to coat the sensing surface, then the coating process is completed, but the structure complexity and process steps increase production cost and generate gas
Solution Approach 1:
The patent replaces the complex heat-transfer method with a UV-curing method. Instead of using heat to transfer and cure the coating, the invention uses UV irradiation to cure the UV-curable clear coating layer. This substitution simplifies the process by eliminating the need for complex heating systems and reduces the number of process steps, thereby lowering production costs.
Solution Approach 2:
The patent extracts and eliminates the heating process from the coating methodology. By using UV-curable materials that cure through UV irradiation rather than heat transfer, the invention removes the complex heating system and associated process steps from the manufacturing process, simplifying the overall structure and reducing production complexity.
3Ease of manufacture
If heat-transfer method is used to coat the sensing surface, then coating is achieved, but gas is generated during manufacturing and defects occur reducing yield
Solution Approach 1:
The patent replaces the heat-transfer method with UV-curing to eliminate gas generation. The UV-curable clear coating layer cures through UV irradiation rather than heat transfer, preventing gas generation during the manufacturing process. This substitution also reduces defects such as pinholes, protrusions, and cracks, thereby improving product yield and reliability.
Solution Approach 2:
The patent converts the potential harm of gas generation and defects into a benefit by using UV-curable materials that cure through UV irradiation. This method eliminates gas generation entirely and produces a defect-free coating surface, transforming the manufacturing process from a source of defects to a source of high-quality, reliable coatings.
4Ease of manufacture
If separate heating process is used in coating, then coating process is completed, but cracking likelihood increases and appearance quality deteriorates
Solution Approach 1:
The patent substitutes the heating process with UV irradiation. The UV-curable clear coating layer is cured through UV irradiation instead of heating, eliminating the thermal stress that causes cracking. This substitution also improves appearance quality by preventing heat-induced defects and maintaining a smooth, defect-free coating surface.
Solution Approach 2:
The patent changes the curing parameter from heat to UV irradiation. By using UV-curable materials that cure through UV irradiation rather than heating, the invention changes the physical and chemical parameters of the curing process. This parameter change eliminates thermal stress and cracking while improving appearance quality through a smoother, defect-free 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 approach reduces the likelihood of cracking and improves the appearance and durability of the sensing surface, while simplifying the manufacturing process and reducing production costs, resulting in higher product yield and improved sensor performance.
Implementation Method 1
The first layer may include a first UV hardening material having a first hardness. The second layer may include a second UV hardening material having a second hardness greater than the first hardness.
Data Source
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AI summary
An electronic device (101) is provided. The electronic device (101) includes a fingerprint sensor (130) including a sensor (130) having a surface including epoxy molding compound "EMC" resin, a first layer (220) disposed on the surface of the sensor (130) or above the surface of the sensor (130), and a second layer (230) disposed on the first layer (220) or above the first layer (220). The first layer (220) includes a first ultraviolet "UV" hardening material having first hardness. The second layer (230) includes a second UV hardening material having second hardness greater than the first hardness and a surface of the second layer (230) has surface roughness less than a specified value.