Flexible PCB Thickness Layout for Foldable Hinge Bending

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing flexible printed circuit boards (FPCBs) in foldable electronic devices face challenges in accommodating varying folding angles and maintaining electrical connectivity while ensuring structural integrity and flexibility.

Innovation Solution

The FPCB design includes a driving area with a specific thickness and signal line spacing that adapts to bending, along with fixed areas of varying thickness and signal line spacing to accommodate different folding angles, ensuring consistent electrical connectivity and structural support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the FPCB uses a uniform thickness design, then the manufacturing process is simple, but the FPCB cannot accommodate varying folding angles while maintaining structural integrity

Engineering Contradiction:

Improveadaptability to varying folding anglesVSAvoidcomplexity of varying thickness design

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The FPCB employs different thicknesses in different regions: a first thickness in the first fixed area, a second thickness in the driving area, and a third thickness in the second fixed area. This local quality variation allows the driving area to flexibly accommodate varying folding angles while the fixed areas maintain structural integrity, resolving the contradiction between adaptability and manufacturing complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The FPCB is segmented into three distinct areas with different thickness characteristics: first fixed area, driving area, and second fixed area. Each segment serves a specific function - the fixed areas provide structural support while the driving area enables folding motion. This segmentation allows the board to handle varying folding angles without requiring a completely complex redesign.

Inventive Principle:

Principle #1Segmentation

2Strength

If the FPCB uses a rigid structure, then the structural integrity is maintained, but the flexibility required for folding operations is reduced

Engineering Contradiction:

Improvestructural integrityVSAvoidflexibility for folding operations

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The FPCB uses local quality variation by implementing different thicknesses in different regions. The fixed areas have greater thickness to maintain structural integrity and strength, while the driving area has reduced thickness to provide the necessary flexibility for folding operations. This resolves the contradiction between maintaining structural integrity and enabling folding flexibility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The FPCB structure transitions from a static uniform design to a dynamic design where the driving area can change its effective stiffness through thickness variation. This allows the board to be rigid where needed for structural support and flexible where needed for folding, dynamically adapting to operational requirements.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the signal line spacing is uniform across the FPCB, then the manufacturing process is simplified, but the electrical performance may deteriorate during bending

Engineering Contradiction:

Improveelectrical connectivity during bendingVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The FPCB implements different signal line spacing in different regions: a first spacing in the first fixed area, a second spacing in the driving area, and a third spacing in the second fixed area. This local quality variation ensures proper electrical performance during bending by adjusting spacing according to the mechanical stress conditions in each area, while still allowing for standardized manufacturing processes.

Inventive Principle:

Principle #3Local quality

4Reliability

If the FPCB cover layer has uniform thickness, then the manufacturing process is simple, but the electrical performance and structural integrity cannot be maintained across varying folding states

Engineering Contradiction:

Improveelectrical performance consistencyVSAvoidcomplexity of varying thickness cover layer

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cover layer thickness is varied locally across different areas of the FPCB. The first cover layer has a first thickness in the first fixed area, a second thickness in the driving area, and a third thickness in the second fixed area. This local quality variation maintains consistent electrical performance across varying folding states by providing appropriate dielectric thickness and mechanical protection in each region, while the segmentation into manufacturing zones keeps the manufacturing process manageable.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP4336810B1Electronic apparatus comprising flexible printed circuit board

Publication Date: 2025.11.05 SAMSUNG ELECTRONICS CO LTD

Figure 1
Figure 2A
Figure 2B

AI summary

An electronic device including a flexible printed circuit board (FPCB) is provided. The electronic device includes a display including a first area and a second area, a first housing supporting the first area, a second housing supporting the second area, a hinge structure foldably connecting the first housing to the second housing based on a folding axis and adjusting a folding angle formed by the first housing and the second housing relative to the folding axis, and an FPCB extending in an extending direction.