Wiring Board Interface Structure for Conductor Adhesion Stability

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Solution Overview

Problem

Existing wiring boards face adhesion issues between the insulation layer and electrical conductor layer due to weak bonding caused by exposed inorganic fillers, leading to potential swelling or peeling of the conductor layer.

Innovation Solution

A wiring board design where the electrical conductor layer is positioned on the surface of exposed insulating particles and insulating resin, avoiding placement below the exposed regions and between the particles and resin, with a seed layer and non-crystalline structure to enhance adhesion, and incorporating protruding portions with voids for stress relief.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If inorganic filler is exposed from the insulation layer surface, then thermal expansion coefficient is reduced, but adhesion between insulation layer and electrical conductor layer deteriorates

Engineering Contradiction:

Improvethermal expansion coefficientVSAvoidadhesion between insulation layer and electrical conductor layer

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies local quality by creating different surface conditions in different regions. The insulating particles are selectively exposed in a first region while a second region maintains good adhesion properties. The electrical conductor layer is positioned to contact both regions, allowing the exposed particle region to provide thermal stability while the adherent region ensures strong bonding.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the surface contact area into distinct regions: a first region where insulating particles are exposed and a second region where the electrical conductor layer contacts the insulation layer directly for strong adhesion. This segmentation allows each region to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If electrical conductor layer is placed on exposed insulating particles, then thermal stability is maintained, but adhesion deteriorates due to weak bonding

Engineering Contradiction:

Improvethermal stabilityVSAvoidadhesion between electrical conductor layer and insulation layer

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent divides the electrical conductor layer's contact area into two functional zones: one zone contacts the exposed insulating particles for thermal stability, while another zone contacts the insulation layer directly for strong adhesion. This segmentation resolves the contradiction by allowing both thermal stability and strong adhesion to coexist in different regions of the same layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different local regions of the electrical conductor layer serve different functions: the portion contacting insulating particles provides thermal stability, while the portion contacting the insulation layer directly provides strong adhesion. This local differentiation allows the system to achieve both thermal stability and strong bonding simultaneously.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If inorganic filler is dispersed in insulation layer, then coefficient of thermal expansion is lowered, but swelling or peeling of conductor layer occurs

Engineering Contradiction:

Improvecoefficient of thermal expansionVSAvoidswelling or peeling resistance of conductor layer

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent segments the interface between the electrical conductor layer and insulation layer into two types of contact regions: one where the conductor layer contacts exposed insulating particles (providing thermal stability) and another where it contacts the insulation layer directly (preventing swelling and peeling). This segmentation allows the system to maintain both thermal expansion control and conductor layer integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the interface exhibit different local qualities: one region allows particle exposure for thermal stability while another region ensures direct bonding for swelling and peeling resistance. This local differentiation enables the system to achieve both thermal expansion control and conductor layer reliability simultaneously.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250386433A1Wiring board and mounting structure using the wiring board

Publication Date: 2025.12.18 KYOCERA CORP

AI summary

A wiring board according to the present disclosure includes a first insulation layer including a first surface, and an electrical conductor layer located on the first surface. The first insulation layer includes an insulating resin, and a plurality of insulating particles dispersed in the insulating resin. The plurality of insulating particles include a first insulating particle including a first region exposed from the insulating resin on the first surface and a second region other than the first region when the first surface is viewed in a top surface view. The electrical conductor layer is located on a surface of the first region and a surface of the insulating resin and is not located below the first region and between the second region and the insulating resin.