Flexible Printed Circuit Board Auto Defect Detection
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Solution Overview
Problem
In-vehicle display systems using chip-on-film (COF) technologies face issues with cracking and bonding defects due to over-bending, which affect the reliability of flexible printed circuit (FPC) boards in reducing occupied space while maintaining functionality.
Innovation Solution
A flexible printed circuit board design featuring a base film with first and second traces and a chip that transmits and receives detection signals to determine normal operation with a display panel and control board, utilizing a detection signal generator, inverter, test signal detector, and equalizer to assess connectivity and functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If chip-on-film (COF) technology is applied to reduce occupied space, then the display system becomes more compact, but the FPC board is prone to cracking and bonding defects due to over-bending
Solution Approach 1:
The patent applies preliminary action by incorporating a detection circuit that proactively monitors the FPC board's condition before actual failure occurs. The detection circuit includes test signal generation units and detection units that continuously check for cracks and bonding defects, enabling early intervention before the over-bending issue causes catastrophic failure.
Solution Approach 2:
The patent implements feedback through a closed-loop detection system where the detection circuit receives test signals, processes them through the FPC board, and analyzes the returned signals to determine the board's condition. This feedback mechanism allows real-time monitoring of the FPC board's integrity, enabling the system to respond to degradation caused by over-bending.
2Adaptability or versatility
If the FPC board is made flexible to enable bending, then the display system achieves better adaptability, but bonding defects occur due to over-bending
Solution Approach 1:
The detection circuit performs preliminary detection of bonding integrity before the FPC board is fully assembled or before over-bending occurs during operation. This allows the system to identify potential bonding issues in flexible regions before they manifest as failures during normal use.
Solution Approach 2:
The feedback mechanism continuously monitors the electrical characteristics of the FPC board to detect changes in bonding quality. When the board is bent during operation, the detection circuit receives feedback signals that indicate whether the flexible connections remain intact or have developed defects.
3Device complexity
If traditional FPC boards are used without defect detection, then the device complexity is lower, but defects cannot be detected automatically requiring manual inspection
Solution Approach 1:
The FPC board performs self-detection through an integrated detection circuit that automatically monitors its own condition. The board generates test signals, routes them through its own traces and bonding interfaces, and analyzes the returned signals to identify defects without requiring external testing equipment or manual inspection.
Solution Approach 2:
The detection circuit is merged with the FPC board structure itself, combining the functional circuitry with the detection infrastructure. The detection units are integrated into the existing board layout, sharing physical space and electrical infrastructure with the operational circuits, thereby reducing overall system complexity.
Data Source
AI summary
A flexible printed circuit (FPC) board includes a base film, a pair of traces and a chip. The pair of traces are disposed on the base film, and each trace has opposite first and second terminals. The chip is disposed on the base film and has pins that are respectively coupled to the first terminals of the traces. When the FPC board is bonded to a panel through the second terminals of the traces that are shorted to each other, the chip is configured to transmit a detection signal through one of the pins and receive a reception signal through the other of the pins, and to determine whether the FPC board works normally with the panel depending on the reception signal.