Fingerprint Sensor Package With 3D Capacitor Structure
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Solution Overview
Problem
Fingerprint sensor packages face challenges in maintaining reliability and sensitivity while achieving a compact size and low cost, with existing solutions failing to effectively reduce financial accidents due to theft or loss of smartcards.
Innovation Solution
A fingerprint sensor package design featuring a package substrate with defined sensing and peripheral regions, including first and second sensing patterns, a coating member, and an upper ground pattern to surround the coating member, along with capacitors that utilize the sensing patterns as conductors to enhance fingerprint recognition and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the fingerprint sensor package uses a compact design with reduced size and thickness, then the overall device dimensions are minimized for smartcard application, but the reliability and sensitivity of fingerprint information acquisition may be compromised
Solution Approach 1:
The patent transitions from planar sensing patterns to a three-dimensional capacitor structure where first and second sensing patterns are stacked vertically with spacing therebetween. This vertical arrangement allows the sensing region to extend in the thickness direction (third direction), effectively increasing the sensing volume without expanding the planar footprint, thus maintaining fingerprint recognition reliability while achieving compact package dimensions suitable for smartcards.
Solution Approach 2:
The patent implements a nested structure where the first sensing patterns and second sensing patterns are positioned in overlapping regions when viewed from the thickness direction, with the coating member covering both sets of patterns. This nested arrangement maximizes the use of available space within the compact package, allowing multiple sensing elements to occupy the same lateral space at different vertical levels, thereby maintaining high sensing density in a reduced volume.
2Ease of manufacture
If the fingerprint sensor package achieves lower manufacturing costs, then economic feasibility is improved for smartcard production, but the quality and sensitivity of fingerprint sensing may deteriorate
Solution Approach 1:
The patent divides the sensing structure into segmented capacitor elements formed by first sensing patterns and second sensing patterns that are spatially separated in the thickness direction. This segmentation allows for simplified manufacturing processes compared to continuous sensing structures, as each pattern can be formed independently through standard photolithography and etching steps. The segmented design maintains sensing sensitivity by preserving the capacitive coupling between separated patterns while reducing manufacturing complexity and cost.
Solution Approach 2:
The patent applies local quality by positioning the coating member specifically over the sensing region containing the first and second sensing patterns, while the peripheral region contains ground patterns for noise reduction. This localized functional differentiation optimizes the sensing quality in the sensing region while using cost-effective ground patterns in the peripheral region, achieving high fingerprint sensing sensitivity without uniformly increasing manufacturing costs across the entire package.
3Reliability
If the fingerprint sensor package includes noise reduction features such as ground patterns, then sensing reliability is improved, but the device complexity and manufacturing steps increase
Solution Approach 1:
The patent merges multiple functions into the sensing patterns themselves: the first and second sensing patterns serve dual purposes as both the sensing elements for fingerprint detection and as the capacitor conductors for noise reduction. By positioning these patterns in a capacitive structure with spacing between them, the same patterns provide both sensing capability and electromagnetic shielding, eliminating the need for separate noise reduction structures and thereby reducing overall device complexity while maintaining high sensing reliability.
Solution Approach 2:
The sensing patterns are designed with multi-functionality, serving simultaneously as capacitive sensing elements for fingerprint detection and as ground references for noise reduction. The first sensing patterns and second sensing patterns function as both the measurement electrodes and the reference electrodes, allowing a single structural element to perform multiple critical functions, thus improving reliability without proportionally increasing device complexity.
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 provides high reliability in fingerprint recognition, reduces sensing noise, and allows for a compact form factor suitable for smartcards, enhancing security and usability while preventing financial accidents.
Implementation Method 1
each capacitor from among the plurality of capacitors includes a sensing pattern from among the plurality of first sensing patterns as a first conductor and a sensing pattern from among the plurality of second sensing patterns as a second conductor
Data Source
AI summary
A fingerprint sensor package includes a package substrate including an upper surface in which a sensing region and a peripheral region surrounding the sensing region are defined, and a lower surface facing the upper surface; a plurality of first sensing patterns located are arranged in the sensing region, are apart from each other in a first direction, and extend in a second direction crossing the first direction; a plurality of second sensing patterns that are arranged in the sensing region, are apart from each other in the second direction, and extend in the first direction; a coating member covering the sensing region; an upper ground pattern in the peripheral region and apart from the coating member to surround the coating member in the first and second directions; and a controller chip on the lower surface of the package substrate; and a plurality of capacitors.