Stepped Wiring Circuit Board Structure to Prevent Cover Layer Peeling

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Solution Overview

Problem

The challenge is to efficiently transmit large currents through a wiring layer while preventing the cover insulating layer from peeling off, especially when the wiring layer thickness is increased to reduce electrical resistance.

Innovation Solution

The wiring layer is designed with a first and second wiring portion, where the second portion's thickness is between 0.7 to 3.0 times that of the first, and both end surfaces of the second portion are positioned inside the width direction of the first portion's end surfaces, creating steps that anchor the cover insulating layer, thereby reducing electrical resistance and preventing peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of the wiring layer is increased to reduce electrical resistance, then the electrical resistance is reduced, but the cover insulating layer is easily peeled off from both ends in the width direction

Engineering Contradiction:

Improveelectrical resistanceVSAvoidpeeling resistance of cover insulating layer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The wiring layer is divided into a first wiring portion and a second wiring portion with different thicknesses. The first wiring portion has a larger width and smaller thickness, while the second wiring portion has a smaller width and larger thickness. This segmentation allows the wiring layer to achieve low electrical resistance through the thicker second portion while the cover insulating layer is protected from peeling by the wider first portion that provides better adhesion area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the wiring layer are given different local properties: the first wiring portion has optimized dimensions for adhesion (larger width) to prevent cover insulating layer peeling, while the second wiring portion has optimized dimensions for electrical conduction (larger thickness). This local quality differentiation resolves the contradiction between peeling resistance and electrical resistance.

Inventive Principle:

Principle #3Local quality

2Reliability

If the width of the wiring layer is widened to increase cross-sectional area, then the electrical resistance is reduced, but the installation space is insufficient

Engineering Contradiction:

Improveelectrical resistanceVSAvoidinstallation space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Instead of increasing the width of the wiring layer (horizontal dimension), the invention increases the thickness of the second wiring portion (vertical dimension). This dimensional change allows the cross-sectional area to be increased for lower electrical resistance without consuming additional horizontal installation space, thus resolving the contradiction between electrical resistance reduction and space constraints.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Strength

If the wiring layer has a stepped structure with first and second wiring portions, then the cover insulating layer peeling is suppressed, but the manufacturing complexity increases

Engineering Contradiction:

Improvepeeling resistance of cover insulating layerVSAvoidwiring layer structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The stepped structure is achieved by changing the dimensional parameters (width and thickness) of different wiring portions rather than introducing completely different structural elements. The first wiring portion has dimensions optimized for adhesion while the second has dimensions optimized for conduction. This parameter-based approach creates the necessary mechanical interlocking to prevent peeling while keeping the manufacturing process relatively simple through controlled dimensional variations.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12507341B2Wiring circuit board and producing method thereof

Publication Date: 2025.12.23 NITTO DENKO CORP

AI summary

A wiring circuit board includes a base insulating layer, a first wiring layer disposed at one side in a thickness direction of the base insulating layer, and a cover insulating layer disposed on one surface in the thickness direction of the base insulating layer so as to cover the first wiring layer. The first wiring layer includes a first wiring portion in contact with one surface of the base insulating layer, and a second wiring portion in contact with one surface in the thickness direction of the first wiring portion. Both end surfaces in a width direction perpendicular to the thickness direction and a transmission direction of the second wiring portion are disposed inside in the width direction with respect to both end surfaces of the first wiring portion.