ESD Grounding via Patterned Thin Film on PCB for Fingerprint Sensor
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Solution Overview
Problem
Semiconductor devices in mobile communication terminals, particularly in fingerprint recognition units, are vulnerable to electrostatic discharge (ESD) due to direct exposure, leading to potential damage and malfunction, as the anti-static resistance decreases with the miniaturization of semiconductor components.
Innovation Solution
An ESD inducing apparatus is integrated into the mobile communication terminal, featuring a ground unit with a patterned thin film and projection pads on the printed circuit board to effectively direct static electricity to the ground, protecting the semiconductor devices from ESD without requiring additional space or devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the semiconductor device is miniaturized to improve performance and reduce terminal size, then the terminal size and weight are decreased, but the anti-static resistance of the semiconductor device is decreased making it more vulnerable to ESD
Solution Approach 1:
The patent applies local quality by creating a ground unit with a specific patterned thin film structure (including projection pads and recesses) at the precise location where the fingerprint sensor contacts the user's finger. This localized ESD protection structure is positioned exactly where static electricity from finger contact would directly impact the semiconductor device, providing targeted protection without affecting other areas of the terminal.
Solution Approach 2:
The ground unit acts as an intermediary between the fingerprint sensor and the semiconductor device. When static electricity is generated through finger contact, the ground unit intercepts and redirects this electrical charge to ground before it can reach and damage the vulnerable miniaturized semiconductor components, thus mediating the harmful ESD effect.
2Reliability
If a ground unit is added to protect against ESD, then the semiconductor device is protected from static electricity, but additional space and device complexity are required
Solution Approach 1:
The ground unit is merged with the existing mounting structure of the fingerprint sensor. The patterned thin film is integrated into the printed circuit board at the mounting location, combining the ESD protection function with the existing sensor mounting area rather than adding a separate, space-consuming protective component.
Solution Approach 2:
The ground unit is implemented as a thin film pattern on the printed circuit board, consisting of conductive material traces and projection pads. This thin film approach provides effective ESD protection while occupying minimal space compared to bulkier protective components, as it utilizes the existing board thickness rather than adding significant volume.
3Reliability
If the ground unit is positioned adjacent to the mounting unit, then ESD can be induced to ground effectively, but the layout complexity of the printed circuit board increases
Solution Approach 1:
The ground unit is segmented into multiple components including projection pads, recesses, and patterned thin film traces. This segmentation allows the ESD protection function to be distributed across multiple small elements rather than requiring a single large complex structure, making the layout more manageable while maintaining effectiveness.
Solution Approach 2:
Instead of trying to protect the semiconductor device directly from ESD, the design inverts the approach by creating a ground unit that actively attracts and redirects static electricity away from the device. The patterned thin film with projection pads creates an inverted structure that channels ESD current toward ground rather than allowing it to reach the vulnerable components.
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 reduces the risk of semiconductor damage from ESD by ensuring static electricity is safely induced to the ground, thereby preventing malfunctions and economic losses, all while maintaining the compact design of the terminal.
Implementation Method 1
a ground unit for inducing a static electricity caused by contacting with the fingerprint, which is provided to the printed board adjacent to the mounting unit
Implementation Method 2
a ground unit for inducing a static electricity caused by contacting with the fingerprint, which is provided to the printed board adjacent to the mounting unit
Data Source
AI summary
The provided is an electrostatic discharging (ESD) inducing apparatus in a mobile communication terminal with a fingerprint recognition function. The ESD inducing apparatus includes: a fingerprint recognizing unit for obtaining fingerprint information by contacting with a fingerprint of a human finger, which is provided to one side of the mobile communication terminal; a printed circuit board provided with a mounting unit contacting with the fingerprint recognizing unit for receiving the fingerprint information from the fingerprint recognizing unit; and a ground unit for inducing a static electricity caused by contacting with the fingerprint, which is provided to the printed circuit board adjacent to the mounting unit.