Flexible Printed Circuit Board Reinforcing Layers for Fracture Resistance
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Solution Overview
Problem
Flexible printed circuit boards (FPCs) used in LCD devices are prone to fracture due to stress during bending, particularly near the light source in backlight modules, which affects luminous efficiency and requires additional reinforcement methods that increase thickness and cost.
Innovation Solution
A flexible printed circuit board design featuring a first reinforcing layer and a second reinforcing layer, both made of metal, strategically positioned to enhance mechanical strength by distributing stress and preventing signal line fractures, with the second reinforcing layer covering a larger area than the signal lines to endure bending stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyimide structure layer or tape is attached to reinforce the FPC, then the mechanical strength is improved, but the overall thickness increases and additional process steps are required
Solution Approach 1:
The patent combines the reinforcing function with the existing FPC structure by integrating reinforcing layers into the circuit board itself, rather than attaching separate reinforcement components. This merging approach provides mechanical strength enhancement without requiring additional assembly processes or increasing overall complexity.
Solution Approach 2:
The reinforcing layers serve multiple functions simultaneously: they provide mechanical strength to prevent fracture during bending, maintain the flexibility of the FPC, and protect the signal lines. This multi-functionality eliminates the need for separate reinforcement components and reduces process complexity.
2Strength
If a polyimide structure layer or tape is attached to reinforce the FPC, then the mechanical strength is improved, but the overall thickness increases
Solution Approach 1:
The patent applies reinforcing layers selectively at specific locations where stress concentration occurs during bending, rather than uniformly throughout the entire FPC. This localized reinforcement provides necessary mechanical strength while minimizing the overall thickness increase, allowing the FPC to fit within tight spaces in backlight modules.
3Ease of operation
If the FPC is made more flexible to accommodate bending, then the ease of operation is improved, but the mechanical strength decreases and fracture risk increases
Solution Approach 1:
The patent employs composite material construction with multiple layers including flexible substrate materials combined with reinforcing layers. This composite structure maintains the flexibility needed for bending operations while the reinforcing layers provide the mechanical strength to prevent fracture, achieving both ease of operation and durability.
Data Source
AI summary
A flexible printed circuit board includes a substrate, signal lines, a first reinforcing layer, and a second reinforcing layer. The first surface of the substrate includes a layout zone and a reinforcing zone disposed nearby the layout zone. The signal lines are disposed on the layout zone. The first reinforcing layer is disposed on the reinforcing zone. The second reinforcing layer is disposed on the second surface of the substrate.