Smart Card Fingerprint Sensor Package With Stacked Substrates
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Solution Overview
Problem
Existing fingerprint sensors face challenges in achieving low cost, reduced size, and maintaining reliability and sensitivity while preventing financial accidents due to theft or loss of smart cards.
Innovation Solution
A fingerprint sensor package design featuring a first substrate with bonding pads and a second substrate with sensing patterns, connected by conductive wires and a controller chip, covered by a molding layer, which includes a core insulating layer and a ground bezel to enhance reliability and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the fingerprint sensor size and thickness are reduced, then the product becomes more compact and cost-effective, but the reliability and sensitivity of fingerprint acquisition may deteriorate
Solution Approach 1:
The sensor is divided into two separate substrates: a first substrate containing bonding pads and external connection pads, and a second substrate containing the sensing patterns and controller chip. This segmentation allows each substrate to be optimized independently for its specific function while maintaining overall compactness.
Solution Approach 2:
The patent transitions from a conventional single-substrate planar layout to a three-dimensional stacked configuration with multiple substrates bonded together. This vertical stacking enables higher integration density, reducing the overall footprint while maintaining sufficient space for reliable sensing elements and connection structures.
2Volume of moving object
If the fingerprint sensor size and thickness are reduced, then the product becomes more compact and cost-effective, but the sensitivity of fingerprint acquisition may deteriorate
Solution Approach 1:
By separating the sensing patterns from the bonding and connection structures onto different substrates, each element can be optimized for its specific function. The sensing patterns on the second substrate can be designed with optimal geometry and spacing for maximum sensitivity without being constrained by bonding pad requirements.
Solution Approach 2:
Different regions of the sensor structure are optimized with different properties: the second substrate is designed with high-sensitivity sensing patterns, while the first substrate is optimized for reliable electrical connections. This localized optimization allows each component to perform its function at peak efficiency within the compact form factor.
3Volume of moving object
If a compact fingerprint sensor design is used, then the overall package size is reduced, but the risk of financial loss from smart card theft or loss increases without adequate security
Solution Approach 1:
The controller chip is integrated directly onto the second substrate with the sensing patterns, and the entire assembly is encapsulated in a single molding layer. This merging of components into a compact, unified package reduces the smart card's overall size while maintaining security functions through the integrated design.
Solution Approach 2:
The patent employs a molding layer that encapsulates multiple components (controller chip, bonding pads, conductive wires) into a unified protective structure. This composite packaging approach provides both physical protection and electrical isolation, enhancing security while maintaining a compact form factor suitable for smart cards.
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 design achieves a thin and reliable fingerprint sensor package suitable for smart cards, providing secure authentication and reducing the risk of financial loss by ensuring accurate fingerprint recognition.
Implementation Method 1
The fingerprint sensor acquires user's fingerprint information using an optical method, a capacitive method, an ultrasonic method, a thermal sensing method, and/or the like
Data Source
AI summary
Provided is a fingerprint sensor package including a first substrate including first bonding pads and an external connection pad, a second substrate attached to the first substrate, the second substrate including a plurality of first sensing patterns spaced apart from each other in a first direction and extending in a second direction intersecting the first direction, a plurality of second sensing patterns spaced apart from each other in the second direction and extending in the first direction, second bonding pads, and test pads, conductive wires electrically connecting the first bonding pads and the second bonding pads, a controller chip connected to the second substrate, and a molding layer covering the controller chip and the second substrate and in contact with the first bonding pads, the second bonding pads, the test pads, and the conductive wires.