Fingerprint Module Pressure Detection Unit Thickness Reduction
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Solution Overview
Problem
The integration of a pressure sensor into fingerprint modules for terminal devices increases the overall thickness, hindering the development of ultra-thin devices, as existing solutions rely on a flexible circuit board and a reinforcing steel sheet, which adds significant thickness.
Innovation Solution
A fingerprint module design featuring a pressure detection unit with a rigid substrate and pressure detection circuit directly formed on it, replacing the reinforcing steel sheet and flexible circuit board, allowing for a thinner profile while maintaining pressure detection functionality, with the rigid substrate providing support for the fingerprint identification chip and facilitating smooth soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible circuit board and reinforcing steel sheet are used to manufacture the pressure sensor, then the pressure detection function is achieved, but the overall thickness of the fingerprint module is greatly increased
Solution Approach 1:
The patent merges the flexible circuit board and reinforcing steel sheet into a single integrated structure. The flexible circuit board is designed to provide both structural support and electrical connection functions, eliminating the need for a separate reinforcing steel sheet. This integration reduces the overall thickness while maintaining both mechanical strength and pressure detection capability.
Solution Approach 2:
The flexible circuit board is designed to serve multiple functions simultaneously: it acts as the pressure sensor substrate, provides structural reinforcement, and serves as the electrical connection interface. This multi-functionality eliminates the need for separate components, thereby reducing thickness while maintaining all required functions.
2Strength
If a reinforcing steel sheet is added to improve the strength of the fingerprint module, then the structural strength is enhanced, but the overall thickness is increased by at least 0.15 millimeters
Solution Approach 1:
The reinforcing steel sheet's structural support function is merged into the flexible circuit board design. The circuit board is constructed with sufficient mechanical strength to provide the required reinforcement without needing a separate steel sheet, thereby eliminating the 0.15mm thickness increase.
Solution Approach 2:
The patent discards the separate reinforcing steel sheet component and recovers its structural support function through the optimized flexible circuit board design. This eliminates the thickness penalty while maintaining the necessary structural strength.
3Ease of manufacture
If the pressure sensor is directly adhered via adhesive to the reinforcing steel sheet, then the assembly is simplified, but the thickness cannot be reduced
Solution Approach 1:
The flexible circuit board and reinforcing steel sheet are merged into a single integrated component. This eliminates the need for adhesive bonding between separate layers, simplifying the manufacturing process while simultaneously reducing the overall thickness by removing the adhesive layer and separate steel sheet.
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 design reduces the overall thickness of the fingerprint module and the device, enhances pressure detection accuracy, and allows for a more flexible selection of substrate materials, such as zirconium oxide ceramic, which provides sufficient rigidity and toughness while minimizing thickness.
Implementation Method 1
a pressure sensor function is further integrated into a fingerprint module, so that the fingerprint module can identify a value of the pressure applied on the fingerprint module
Data Source
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AI summary
Provided are a fingerprint module and a mobile terminal in some embodiments of the present disclosure. The fingerprint module includes a fingerprint identification chip, a flexible circuit board, and a pressure detection unit. The pressure detection unit includes a rigid substrate and a pressure detection circuit formed on the rigid substrate. The fingerprint identification chip and the pressure detection unit are disposed on two opposite surfaces of the flexible circuit board respectively, and are separately electrically connected to the flexible circuit board respectively. In the embodiments of the disclosure, the pressure detection circuit is directly formed on the rigid substrate, and the rigid substrate with the pressure detection circuit replaces a reinforcing steel sheet and a flexible circuit board for manufacturing a pressure sensor in the existing art. Such design can not only achieve a pressure detection function, but also decrease an overall thickness of the fingerprint module and reduce an impact of the fingerprint module on the overall thickness of a device.