Flexible Wiring Board Segmented Rigid Flexible Portions

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Solution Overview

Problem

There is a demand for flexible wiring boards with higher reliability, especially higher connection reliability, and low manufacturing costs, as existing technologies do not adequately address these requirements.

Innovation Solution

A flexible wiring board structure comprising a first flexible base material with a conductor pattern, a second flexible base material adjacent to it, and an insulating layer that exposes part of the first base material, with a conductor pattern formed on the insulating layer and a plating layer connecting the conductor patterns through vias, using materials like polyimide and polyester for enhanced flexibility and heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flexible wiring board uses conventional connection structures, then manufacturing cost is reduced, but connection reliability deteriorates

Engineering Contradiction:

Improveconnection reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The wiring board is divided into a rigid portion and a flexible portion, with the rigid portion providing stable connection points and the flexible portion enabling bending. This segmentation allows the connection structure to maintain reliability during bending while keeping manufacturing costs manageable through modular construction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite structures combining rigid and flexible materials in a single wiring board. The rigid portion provides structural stability for reliable connections, while the flexible portion enables bending capability. This composite approach resolves the contradiction by integrating both reliability and flexibility without significantly increasing manufacturing complexity.

Inventive Principle:

Principle #40Composite materials

2Strength

If the wiring board structure is simplified, then manufacturing cost is reduced, but stress on joints increases

Engineering Contradiction:

Improvejoint durabilityVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

By segmenting the wiring board into rigid and flexible portions, the structure can be simplified in terms of material usage while maintaining joint durability. The rigid portion handles stress concentration at joints, while the flexible portion absorbs bending stresses, reducing overall structural complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rigid portion is strategically positioned at locations where stress concentration occurs, such as near connection points and bends. This local reinforcement approach maintains joint durability without requiring the entire wiring board to be complex or rigid, thus avoiding unnecessary structural complexity.

Inventive Principle:

Principle #3Local quality

3Temperature

If flexible base material is used throughout, then flexibility is improved, but heat resistance deteriorates

Engineering Contradiction:

Improveheat resistanceVSAvoidflexibility

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The wiring board is segmented into rigid and flexible portions, allowing each region to be optimized for its specific function. The rigid portion provides heat resistance in areas requiring thermal stability, while the flexible portion maintains flexibility where bending is needed. This segmentation resolves the contradiction between heat resistance and flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the wiring board are assigned different material properties: the rigid portion uses heat-resistant materials in regions experiencing high temperatures, while the flexible portion uses flexible materials where bending is required. This local quality approach allows simultaneous optimization of heat resistance and flexibility without compromising either property globally.

Inventive Principle:

Principle #3Local quality

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

The solution provides high connection reliability and cost-effective manufacturing by reducing stress on joints, enhancing durability, and maintaining performance under mechanical bending and heat, while using cost-effective materials for the flexible wiring board.

Implementation Method 1

a plating layer is provided connecting the conductor pattern of the first flexible base material and the conductor pattern on the insulating layer

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 2

a via is formed in the insulating layer and connecting the conductor pattern of the first flexible base material and the conductor pattern on the insulating layer

Methodology Applied

Scientific EffectMechanical drilling:

Data Source

PatentUS8405999B2Flexible wiring board and method of manufacturing same

Publication Date: 2013.03.26 IBIDEN CO LTD

AI summary

A flexible wiring board includes a first flexible base material with a conductor pattern formed thereon, a second flexible base material disposed adjacent to the first flexible base material and an insulating layer covering the first flexible base material and the second flexible base material. The insulating layer exposes at least one portion of the first flexible base material. A conductor pattern is formed on the insulating layer, and a plating layer is provided connecting the conductor pattern of the first flexible base material and the conductor pattern on the insulating layer.