PCB Bending Region Via Hole Stress Distribution
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Solution Overview
Problem
Printed circuit boards (PCBs) face durability issues in bending regions due to stress concentration, leading to potential cracks and damage to electrical connections, which can shorten the lifespan of electronic devices.
Innovation Solution
The PCB design includes an extending region and a bending region with a non-conductive layer and conductive layers, where the via holes in the bending region have different cross-sectional areas between the conductive layers, effectively dispersing stress and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive via is included in the bending portion of the printed circuit board, then electrical connections between different conductive layers are established, but stress concentration occurs in the region adjacent to the via, leading to cracks and reduced durability
Solution Approach 1:
The patent applies local quality by making the via hole cross-sectional area different at different locations within the via hole itself. Specifically, the cross-sectional area of the via hole is made smaller at the first conductive layer side and larger at the second conductive layer side in the bending region. This non-uniform geometry locally redistributes stress concentration, preventing cracks while maintaining electrical connectivity.
Solution Approach 2:
The patent changes the geometric parameter of the via hole by creating a non-uniform cross-sectional area profile. The via hole transitions from a smaller cross-sectional area at the first conductive layer to a larger cross-sectional area at the second conductive layer. This parameter variation allows the via hole to accommodate bending stress more effectively, preventing crack initiation and propagation while maintaining electrical connection functionality.
2Ease of manufacture
If the via hole cross-sectional area is made uniform throughout, then manufacturing is simplified, but stress concentration occurs at the bending region causing cracks
Solution Approach 1:
The patent implements local quality by creating a via hole with non-uniform cross-sectional area, where the geometry varies specifically in the bending region. The cross-sectional area is smaller at the first conductive layer and larger at the second conductive layer, providing localized stress distribution benefits without requiring complete redesign of the entire via structure.
Solution Approach 2:
The patent applies parameter changes by varying the cross-sectional area parameter of the via hole along its length. This creates a gradient structure that optimizes stress distribution in the bending region while maintaining manufacturability through standard via formation processes, balancing manufacturing simplicity with enhanced crack resistance.
3Volume of moving object
If the printed circuit board is bent to secure mounting space, then device miniaturization is achieved, but stress concentration in the bending portion leads to electrical connection damage
Solution Approach 1:
The patent applies local quality by creating a via hole with non-uniform cross-sectional area specifically in the bending region. The cross-sectional area varies from smaller at the first conductive layer to larger at the second conductive layer, providing localized stress distribution that prevents crack formation while allowing the PCB to be bent for device miniaturization.
Solution Approach 2:
The patent changes the geometric parameter of the via hole to create a stress-distributing structure. By varying the cross-sectional area along the via hole length, the design accommodates bending stresses that arise from miniaturization, preventing electrical connection damage while maintaining compact device form factor.
Data Source
AI summary
A printed circuit board is provided. The printed circuit board includes: an extending region extending along one direction, and a bending region configured to bend with respect to the extending region. The extending region and the bending region includes a non-conductive layer, a first conductive layer disposed on one surface of the non-conductive layer, a second conductive layer disposed on the other surface of the non-conductive layer, and at least one via hole penetrating the non-conductive layer, the first conductive layer, and the second conductive layer. In the bending region, a cross-sectional area of the via hole in contact with the first conductive layer is less than a cross-sectional area of the via hole in contact with the second conductive layer.