Wiring Substrate Two-Layer Insulation Adhesion

Solution Overview

Problem

Existing wiring substrates face challenges in achieving a balance between high adhesion strength of conductor layers and low dielectric loss tangent, particularly when using inorganic filler particles, as they often result in inadequate insulation between conductor patterns and risk of short circuits.

Innovation Solution

A wiring substrate design featuring a two-layer insulating structure with a first layer containing a high content of inorganic filler particles and a second layer with a lower content, where the metal film is formed between the second inorganic filler particles and resin, enhancing adhesion and reducing dielectric loss by optimizing the thickness and surface roughness of the insulating layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If inorganic filler particles are used in the insulating layer, then adhesion strength between conductor layer and insulating layer is improved, but dielectric loss tangent increases and insulation between conductor patterns deteriorates

Engineering Contradiction:

Improveadhesion strengthVSAvoidinsulation between conductor patterns

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The insulating layer is divided into two distinct layers: a first insulating layer with high inorganic filler content (60-90 mass%) for strong adhesion, and a second insulating layer with low inorganic filler content (0-30 mass%) for good insulation. This segmentation allows each layer to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the insulating layer have different compositions optimized for their specific functions. The first layer near the conductor pattern uses high filler content for adhesion, while the second layer uses low filler content for insulation, creating local quality variations that resolve the contradiction.

Inventive Principle:

Principle #3Local quality

2Strength

If inorganic filler particles are used in the insulating layer, then adhesion strength between conductor layer and insulating layer is improved, but dielectric loss tangent increases

Engineering Contradiction:

Improveadhesion strengthVSAvoiddielectric loss tangent

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The insulating layer is divided into two distinct layers: a first insulating layer with high inorganic filler content (60-90 mass%) for strong adhesion, and a second insulating layer with low inorganic filler content (0-30 mass%) for good insulation. This segmentation allows each layer to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the insulating layer have different compositions optimized for their specific functions. The first layer near the conductor pattern uses high filler content for adhesion, while the second layer uses low filler content for insulation, creating local quality variations that resolve the contradiction.

Inventive Principle:

Principle #3Local quality

3Strength

If conductor patterns are formed on insulating layer with inorganic filler particles, then adhesion strength is improved, but risk of short circuits increases

Engineering Contradiction:

Improveadhesion strengthVSAvoidrisk of short circuits

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The insulating layer is divided into two distinct layers: a first insulating layer with high inorganic filler content (60-90 mass%) for strong adhesion, and a second insulating layer with low inorganic filler content (0-30 mass%) for good insulation. This segmentation allows each layer to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the insulating layer have different compositions optimized for their specific functions. The first layer near the conductor pattern uses high filler content for adhesion, while the second layer uses low filler content for insulation, creating local quality variations that resolve the contradiction.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20240206061A1Wiring substrate

Publication Date: 2024.06.20 IBIDEN CO LTD

AI summary

A wiring substrate includes an insulating layer including a first layer and a second layer, and a conductor layer including a metal film formed on a surface of the second layer of the insulating layer such that the conductor layer includes a conductor pattern. The first layer includes resin and first inorganic particles, the second layer includes resin and second inorganic particles at the content rate that is lower than the content rate of the first inorganic particles in the first layer, and the thickness of the first layer is 90% or more of the thickness of the insulating layer. The second layer of the insulating layer includes a composite layer having the thickness in the range of 0.1 to 0.3 μm, and the composite layer includes part of the metal film in the conductor layer formed in gaps between the second inorganic particles and resin in the second layer.