Capacitive Fingerprint Module Conductive Adhesive Layers
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Solution Overview
Problem
Capacitive fingerprint sensing modules face challenges in achieving high accuracy and conductivity, which are crucial for reliable fingerprint identification in various electronic devices.
Innovation Solution
A capacitive fingerprint sensing module is designed with a flexible printed circuit board, lower and upper conductive adhesive layers, and a positioning frame, where the conductive adhesive layers enhance conductivity and accuracy by covering sensing electrodes and providing support, while the upper conductive adhesive layer also offers scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensing electrodes without conductive adhesive layers are used, then the device structure remains simple, but the sensing accuracy and conductivity are insufficient
Solution Approach 1:
The patent applies composite materials by combining conductive adhesive layers with sensing electrodes to create a multi-layer structure. The conductive adhesive layer (comprising conductive particles in a polymer matrix) is integrated with the sensing electrode layers, forming a composite structure that enhances electrical conductivity and sensing accuracy while maintaining structural integrity
Solution Approach 2:
The conductive adhesive layers are applied locally at specific positions where conductivity enhancement is needed - between the upper and lower sensing electrodes and at the electrode edges. This localized application improves sensing accuracy at critical areas without unnecessarily complicating the entire device structure
2Measurement precision
If the conductive adhesive layers are applied to enhance conductivity, then sensing accuracy improves, but the vulnerability to external damage increases
Solution Approach 1:
The patent implements beforehand cushioning by adding a protective layer over the conductive adhesive layers and sensing electrodes. This protective layer is applied in advance to prevent external damage such as scratches and mechanical stress, thereby protecting the vulnerable conductive structures while maintaining their enhanced sensing capabilities
Solution Approach 2:
The protective layer is integrated with the conductive adhesive structure to form a composite assembly. This composite structure combines the conductivity-enhancing properties of the adhesive layers with the protective properties of the outer layer, simultaneously addressing both sensing accuracy and durability requirements
3Measurement precision
If precise positioning of sensing electrodes is achieved through accurate adhesive layer placement, then sensing accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the conductive adhesive layers with specific patterns and positions before assembling the complete sensing module. The adhesive layers are prepared in advance with precise geometries that correspond to the sensing electrode locations, ensuring accurate positioning without requiring complex real-time alignment during manufacturing
Solution Approach 2:
The conductive adhesive layers serve as an intermediary element that facilitates precise positioning between the upper and lower sensing electrodes. The adhesive layers act as a mediator that holds the electrodes in accurate relative positions, enabling precise fingerprint feature point detection while simplifying the manufacturing process through a self-aligning structure
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 significantly improves the accuracy and conductivity of capacitive fingerprint sensing, enhancing the reliability of fingerprint identification and extending the module's lifespan by protecting the conductive layers from damage.
Implementation Method 1
The lower conductive adhesive layer is formed on the second sensing layer of the flexible printed circuit board and configured to cover the second sensing electrodes
Data Source
AI summary
A capacitive fingerprint sensing module includes a flexible printed circuit board, a lower conductive adhesive layer, an upper conductive adhesive layer, and a positioning frame. The flexible printed circuit board has an upper surface and a lower surface. The upper surface has a finger pressing region and a first sensing layer. The lower surface has a second sensing layer. The lower conductive adhesive layer is formed on the second sensing layer and provided to cover second sensing electrodes mounted on the second sensing layer. The upper conductive adhesive layer is formed on the finger pressing region. The positioning frame has an opening facing upward and a slot. The flexible printed circuit board is inserted through the slot and embedded in the positioning frame. Accordingly, effects of conductivity enhancement and accuracy improvement of the capacitive fingerprint sensing module are produced.