Flexible Wired Circuit Board Production Method

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Solution Overview

Problem

Conventional methods for producing printed wiring boards do not meet the demand for excellent elastic properties required for wearable devices.

Innovation Solution

A method involving forming a seed layer, a conductive pattern, covering with an insulating layer, peeling, and removing the seed layer, where the insulating layer has a folding endurance of 10 times or more, using materials like urethane-(meth)acrylic resin or silicone resin to achieve flexibility and toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional producing methods using thermosetting resin (epoxy resin) are used, then the wired circuit board can be produced with standard structural properties, but the elastic properties and flexibility required for wearable devices cannot be achieved

Engineering Contradiction:
Improveelastic propertiesVSAvoidmaterial selection constraint
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from conventional thermosetting resin (epoxy resin) to flexible resin materials such as polyimide resin, polyethylene terephthalate (PET), or polyvinylidene fluoride (PVDF). This parameter change in material selection enables the wired circuit board to achieve excellent elastic properties and flexibility while maintaining manufacturability through established production methods

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures by combining flexible resin materials with conductive patterns and insulating layers. The insulating layer is formed of flexible resin material that provides both mechanical flexibility and electrical insulation, creating a composite structure that achieves both elastic properties and functional requirements for wearable devices

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If the insulating layer is made from flexible materials to achieve elastic properties, then the folding endurance improves to 10 times or more, but the material selection is limited to specific resin types

Engineering Contradiction:
Improvefolding enduranceVSAvoidmaterial selection range
Core Design Contradiction:
Duration of action of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent specifies parameter changes in material selection, limiting insulating layer materials to flexible resin types such as polyimide resin, PET, or PVDF. This parameter constraint ensures folding endurance of 10 times or more while providing sufficient versatility through multiple suitable material options that can be selected based on specific application requirements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by selecting specific resin materials for the insulating layer that provide both flexibility and electrical insulation properties. Each resin type (polyimide, PET, PVDF) offers distinct local properties that can be optimized for specific wearable device applications while maintaining the required folding endurance

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If a peeling layer and seed layer structure is used to form conductive patterns, then the conductive pattern formation precision is improved, but the manufacturing process complexity increases

Engineering Contradiction:
Improveconductive pattern formation precisionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by forming a peeling layer on the flexible substrate before forming the seed layer and conductive patterns. This preliminary structure enables precise conductive pattern formation through plating processes while maintaining flexibility. The peeling layer is removed after pattern formation, having served its purpose of enabling precise manufacturing without permanently adding complexity to the final product

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3322265B1Producing method of wired circuit board
Publication Date: 2023.09.06 NITTO DENKO CORP
  • EP3322265B1 patent drawingFigure 1~2
  • EP3322265B1 patent drawingFigure 3A~3F
  • EP3322265B1 patent drawingFigure 4A~4C

AI summary

A method for producing a wired circuit board includes a step (1) of forming a seed layer on one surface in a thickness direction of a peeling layer, a step (2) of forming a conductive pattern on one surface in the thickness direction of the seed layer, a step (3) of covering the seed layer and the conductive pattern with an insulating layer, a step (4) of peeling the peeling layer from the seed layer, and a step (5) of removing the seed layer. The insulating layer has the number of times of folding endurance measured in conformity with JIS P8115 (2001) of 10 times or more.