Fingerprint Sensor Package Wiring Crack Prevention
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Solution Overview
Problem
Fingerprint sensor packages in authentication cards are prone to wiring cracks due to their thin thickness and frequent use, leading to card malfunction and inconvenience.
Innovation Solution
A fingerprint sensor package design that includes a substrate with an insulating and wiring layer, a fingerprint sensor chip, a molding material with distinct regions, and a buffer member to absorb pressure and prevent wiring cracks, all without increasing the package thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the fingerprint sensor package is made thin to fit in the authentication card, then the card thickness is reduced and fits better in wallets, but the wiring becomes more susceptible to cracks during frequent use
Solution Approach 1:
The molding material is divided into a first region with higher thickness over the fingerprint sensor chip and a second region with lower thickness extending to the edge. This local variation in thickness provides structural support where needed while maintaining overall thinness, preventing wiring cracks without significantly increasing package thickness
Solution Approach 2:
The buffer member is positioned between the card body and the second region of the molding material to absorb external pressure before it reaches the wiring. This preemptive cushioning protects the wiring from cracks caused by bending and torsion during frequent card usage
2Reliability
If a buffer member is added to prevent wiring cracks, then the reliability improves, but the device complexity increases
Solution Approach 1:
The buffer member is integrated into the molding material structure, merging the protection function with the existing package components. This consolidation adds crack resistance while minimizing increases in structural complexity
Solution Approach 2:
The buffer member is positioned only in the second region where it is most needed for protection, rather than uniformly throughout the entire package. This localized approach provides necessary protection while keeping the overall structure simple and manageable
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 effectively prevents wiring cracks in the fingerprint sensor package, ensuring reliable operation even under stress conditions such as bending and torsion, thereby reducing card replacement inconvenience.
Implementation Method 1
a buffer member on the second region of the molding material... capable of preventing cracks in a wiring pattern
Implementation Method 2
a molding material on the substrate to mold the fingerprint sensor chip and including a first region and a second region surrounding the first region... vertical level of an upper surface of the second region of the molding material is lower than a vertical level of an upper surface of the first region of the molding material
Data Source
AI summary
A fingerprint sensor package includes: a substrate including an insulating layer and a wiring layer; a fingerprint sensor chip on the substrate; a molding material to mold the fingerprint sensor chip on the substrate and including a first region and a second region surrounding the first region; and a buffer member on the second region of the molding material; the wiring layer includes a wiring pattern extending from an inside to an outside of the molding material; a vertical level of an upper surface of the second region of the molding material is lower than a vertical level of an upper surface of the first region of the molding material.