Fingerprint Sensor Ceramic Layer Assembly Without Thermal Deformation

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Solution Overview

Problem

The attachment of a ceramic layer to a fingerprint recognition sensor using a thermosetting adhesive requires a high-temperature thermal curing process, which can deform the sensor's exterior surface and expose sharp edges, posing a risk of injury and limiting its placement on electronic device surfaces.

Innovation Solution

A sensor module with a fingerprint recognition sensor enclosed by a protection layer, using a UV curing adhesive member and a ceramic layer that allows UV penetration, eliminating the need for high-temperature curing and processing the sensor module's edges to remove sharp edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a thermosetting adhesive member is used to attach the ceramic layer to the fingerprint recognition sensor, then strong adhesion is achieved, but high-temperature thermal curing causes surface deformation of the sensor

Engineering Contradiction:
Improveadhesion strengthVSAvoidsurface flatness
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the curing parameter from thermal (high temperature) to UV light activation. The UV-curable adhesive member allows curing at room temperature through UV irradiation, eliminating the thermal deformation issue while maintaining strong adhesion between the ceramic layer and fingerprint recognition sensor

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal curing mechanism with a UV photochemical curing mechanism. Instead of using heat to activate the adhesive, UV light is used to initiate polymerization of the UV-curable adhesive, thereby avoiding thermal effects on the sensor surface

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If the sharp edge of the ceramic layer is not protected, then the structure remains simple, but the sharp edge may inflict injury on the user

Engineering Contradiction:
Improvestructure complexityVSAvoidinjury risk
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies edge processing to the ceramic layer to replace sharp edges with curved or rounded surfaces. This curvature modification eliminates the injury risk while maintaining the protective function of the ceramic layer, and the processed edge also provides aesthetic improvement

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Volume of moving object

If the fingerprint recognition sensor is mounted on a side surface of the electronic device, then space utilization is improved, but the sharp edge of the ceramic layer becomes exposed to the outside

Engineering Contradiction:
Improvespace utilizationVSAvoidedge exposure
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent processes the edge of the ceramic layer to create a curved surface that is safe for user contact. This allows the sensor module to be mounted on side surfaces where the edge may be exposed, transforming the harmful sharp edge into a safe curved profile while maintaining space-efficient design

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 solution prevents surface deformation and sharp edge injuries, allowing the sensor module to be safely placed on various device surfaces, including the front, rear, and side, while maintaining surface flatness and durability.

Implementation Method 1

a UV curing adhesive member disposed on the protection layer

Methodology Applied
Scientific EffectUV curing: Photopolymerisation

Data Source

PatentEP3961346B1Electronic device comprising sensor module
Publication Date: 2025.12.24 SAMSUNG ELECTRONICS CO LTD
  • EP3961346B1 patent drawingFigure 1
  • EP3961346B1 patent drawingFigure 2
  • EP3961346B1 patent drawingFigure 3

AI summary

An electronic device is provided. The electronic device includes a housing and a sensor module disposed in at least a portion of the housing. The sensor module comprises: a fingerprint recognition sensor; a protective layer covering the fingerprint recognition sensor; an adhesive member placed on the protective layer; and a ceramic layer placed on the adhesive member, wherein the edge of the ceramic layer, the edge of the adhesive member, and the edge of a part of the protective layer include machined surfaces. Other embodiments are also possible.