Two-Board Rigid-Flex PCB Assembly for Automotive Camera Alignment
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Solution Overview
Problem
Automotive cameras face misalignment issues due to mechanical strain and thermal expansion, primarily caused by connectors and power dissipating components, which affect image quality and reliability.
Innovation Solution
The image sensor is separated from connectors and high power components by using a flexible circuit to connect two rigid PCBs, minimizing strain and heat transfer, allowing precise alignment and isolation between the PCBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the image sensor and connector are integrated on the same rigid PCB, then the device complexity is reduced, but the alignment precision deteriorates due to mechanical strain and thermal expansion
Solution Approach 1:
The patent divides the PCB into two separate rigid PCBs: one carrying the image sensor and another carrying the connector. This segmentation isolates the image sensor from mechanical strain and thermal expansion effects caused by connector operations, thereby maintaining precise alignment between the image sensor and lens stack while still achieving functional integration through the flexible circuit connection.
Solution Approach 2:
A flexible circuit serves as an intermediary element connecting the two rigid PCBs. This flexible circuit acts as a mediator that transmits electrical signals between the image sensor PCB and connector PCB while accommodating relative movements and isolating mechanical stresses, thus preserving alignment precision without requiring direct rigid integration.
2Device complexity
If connectors and high power components are placed on the same PCB as the image sensor, then the device complexity is reduced, but the reliability deteriorates due to thermal warpage and mechanical strain
Solution Approach 1:
The patent segments the component layout by placing heat-generating components (connectors and high-power electronics) on a separate rigid PCB from the image sensor. This physical separation prevents thermal warpage and mechanical strain from affecting the image sensor alignment, thereby improving reliability while maintaining functional integration through the flexible circuit interconnection.
Solution Approach 2:
The patent extracts the connector and high-power components from the image sensor PCB, placing them on a separate rigid PCB. This extraction removes the sources of thermal expansion and mechanical stress from proximity to the image sensor, ensuring stable alignment and reliable operation while preserving electrical connectivity through the flexible circuit.
3Strength
If a rigid connection is used between PCBs, then the structural strength is improved, but the manufacturing precision deteriorates due to stress transfer
Solution Approach 1:
The patent employs a flexible circuit (a flexible thin film structure) to connect the two rigid PCBs. This flexible circuit provides sufficient electrical connectivity and mechanical coupling while accommodating relative movements between the rigid PCBs without transferring stress to the image sensor, thereby maintaining alignment precision while ensuring structural integrity.
Solution Approach 2:
The patent introduces dynamic flexibility into the PCB connection system by using a flexible circuit that can bend and accommodate relative movements between the two rigid PCBs. This dynamic connection allows the rigid PCBs to maintain their structural strength while the flexible circuit absorbs stress and prevents stress transfer to the image sensor, preserving manufacturing precision.
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
This approach maintains precise optical alignment, reduces mechanical and thermal stress, and facilitates assembly and serviceability of automotive cameras.
Implementation Method 1
heat conduction to the image sensor (e.g., from the second rigid PCB, etc.) is significantly reduced or eliminated
Implementation Method 2
the flex circuit that electrically connects the image sensor PCB to the connector PCB allows for significant misalignment between the two PCBs
Data Source
AI summary
A camera assembly includes a first printed circuit board separated from a second printed circuit board. A flex circuit electrically connects the first printed circuit board to the second printed circuit board. An image sensor is attached to the first printed circuit board and a connector is attached to the second printed circuit board. The image sensor of the camera assembly is mechanically and physically separate from the connector. The first printed circuit board is connected to the second printed circuit board via a flexible circuit. The flexible circuit is elastically moveable between an assembled state and a disassembled state.