Rigid-Flex PCB Diagnostic Trace for Open-Circuit Detection
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Solution Overview
Problem
Conventional rigid-flex PCBs lack a mechanism to indicate disconnections or severing of signal communication between rigid and flex circuits, which can lead to undetected damage or breakage due to increased stress from bending.
Innovation Solution
A built-in diagnostic circuit with a serpentine diagnostic trace and a diagnostic device is integrated into the rigid-flex PCB, allowing continuous monitoring and detection of open circuits through a light-emitting diode or processor-based fault detection, generating alerts for potential faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid-flex PCB is used to combine flexibility and rigidity, then the PCB can be shaped and reduced in space consumption, but there is no mechanism to detect disconnections or damage to signal traces
Solution Approach 1:
The patent implements a diagnostic trace and diagnostic device that proactively monitor the health of signal traces before failures occur. The diagnostic trace is pre-configured to follow the same physical path as signal traces through flex circuits and joint regions, enabling early detection of potential issues such as open circuits, disconnections, or damage due to physical stress.
Solution Approach 2:
The patent introduces a diagnostic device as an intermediary component that mediates between the signal traces and the monitoring system. This diagnostic device electrically couples to the diagnostic trace and translates physical trace conditions into detectable electrical signals, enabling indirect observation of trace health without interfering with normal signal transmission.
2Area of stationary object
If signal traces are routed through flex circuits and joint regions, then connectivity and space efficiency are improved, but the traces become vulnerable to physical stress and disconnection
Solution Approach 1:
The diagnostic trace is pre-configured to traverse the same high-stress regions (flex circuits and joint areas) as the signal traces, enabling proactive monitoring of physical stress effects before they cause actual signal trace failure.
Solution Approach 2:
The diagnostic device provides continuous feedback about the condition of traces passing through flex circuits and joint regions. When physical stress causes impedance changes or open circuits in the diagnostic trace, the system receives immediate feedback and can trigger alerts or protective actions before critical failures occur.
3Ease of manufacture
If conventional PCB design is used without diagnostic circuits, then manufacturing cost is reduced, but system failures occur without notification
Solution Approach 1:
The diagnostic circuit is designed to be self-monitoring, automatically detecting and reporting faults without requiring external inspection or intervention. The diagnostic device continuously checks the health of signal traces and autonomously generates fault notifications when issues are detected, enabling the system to self-diagnose problems.
Solution Approach 2:
The diagnostic system establishes a feedback loop that continuously monitors trace integrity and provides immediate notification when failures occur. The diagnostic device converts physical trace conditions into electrical signals that trigger alerts, ensuring that system operators are promptly informed of any disconnections or damage.
Data Source
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AI summary
A rigid-flex printed circuit board (PCB) includes at least one rigid PCB including at least one electrical component, a flex circuit, and a built-in diagnostic circuit. The flex circuit includes at least one end connected to the at least one rigid PCD. The flex circuit includes at least one signal trace configured to deliver an electrical signal to the at least one electrical component. The built-in diagnostic circuit is configured to detect a fault in the rigid-flex PCB.