Rigid-Flex PCB Notch Structure for Lamination Flatness
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Solution Overview
Problem
The uneven outer surface of rigid-flexible PCBs due to the extended cover layer during lamination affects performance and reliability.
Innovation Solution
A rigid board with notches is laminated to a flexible board, with insulating and conductive layers, and protective layers are applied to maintain flatness and protect against delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover layer extends toward the rigid area to prevent separation, then the protective function is improved, but the outer surface becomes uneven
Solution Approach 1:
The rigid board is segmented by creating a notch that divides its structure into regions that can accommodate the extended cover layer. This segmentation allows the cover layer to extend toward the rigid area for protection while the notch absorbs the volume difference, maintaining the outer surface flatness.
Solution Approach 2:
The extended cover layer is nested within the notch of the rigid board structure. The notch acts as a recessed space that contains the extended portion of the cover layer, allowing it to provide protection without protruding and creating surface unevenness.
2Reliability
If the cover layer extends toward the rigid area, then delamination is prevented, but manufacturing complexity increases
Solution Approach 1:
The rigid board is segmented by creating a notch that divides its structure into regions that can accommodate the extended cover layer. This segmentation allows the cover layer to extend toward the rigid area for protection while the notch absorbs the volume difference, maintaining the outer surface flatness.
Solution Approach 2:
The notch is pre-formed in the rigid board before the cover layer is applied and extended. This preliminary action prepares the structure in advance to receive and accommodate the extended cover layer, simplifying the subsequent lamination process and reducing manufacturing complexity.
Data Source
AI summary
A preparation method for a rigid-flexible printed circuit board involves initially providing a flexible board, divided into two regions along its extension direction. A first protective layer is applied to the flexible board, with distinct parts covering the two regions respectively. Subsequently, a rigid board is positioned in the second region, designed with a notch to alleviate height discrepancies introduced by the protective layer. The final step involves laminating the rigid board to the flexible board. This ensures the portion of the rigid board adjacent to the second portion is aligned flush with the rest, resulting in a rigid-flex PCB with improved flatness. This method is particularly significant for applications requiring precise structural integrity and consistency in electronic devices.