Wiring Board Insulating Layer Segmentation for Void Prevention

Solution Overview

Problem

Conventional build-up wiring boards without reinforcing members are weak, and when prepregs with reinforcing members are used, insulation reliability is compromised due to high melt viscosity and potential void formation between fine wiring layers.

Innovation Solution

A wiring board design featuring a coreless build-up structure with a first insulating film composed of only resin and a second insulating film with a reinforcing member impregnated resin, where the reinforcing member is separated from the wiring layer, ensuring adequate resin embedding and preventing void formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If prepreg with reinforcing member is used as outermost insulating layer to retain strength, then wiring board strength is improved, but insulation reliability deteriorates due to potential contact between reinforcing member and wiring layer

Engineering Contradiction:

Improvewiring board strengthVSAvoidinsulation reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The insulating layer is divided into two separate films: a first insulating film (prepreg with reinforcing member) and a second insulating film (resin-only). This segmentation allows the reinforcing member to provide strength while the second film acts as an insulating barrier between the wiring layer and the reinforcing member, preventing contact and maintaining insulation reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second insulating film composed of only resin serves as an intermediary layer between the wiring layer and the reinforcing member in the first insulating film. This intermediate resin layer ensures that the wiring layer does not directly contact the reinforcing member, thereby maintaining insulation reliability while still allowing the reinforcing member to provide structural strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If prepreg with reinforcing member is used, then wiring board strength is improved, but manufacturing precision deteriorates due to high melt viscosity and insufficient resin embedding

Engineering Contradiction:

Improvewiring board strengthVSAvoidresin embedding quality

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The insulating layer is divided into two separate films: a first insulating film (prepreg with reinforcing member) and a second insulating film (resin-only). This segmentation allows the reinforcing member to provide strength while the second film acts as an insulating barrier between the wiring layer and the reinforcing member, preventing contact and maintaining insulation reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second insulating film composed of only resin serves as an intermediary layer between the wiring layer and the reinforcing member in the first insulating film. This intermediate resin layer ensures that the wiring layer does not directly contact the reinforcing member, thereby maintaining insulation reliability while still allowing the reinforcing member to provide structural strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If outermost insulating layer is made thin, then device complexity is reduced, but reliability deteriorates as reinforcing member contacts wiring layer

Engineering Contradiction:

Improveinsulating layer thicknessVSAvoidinsulation reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The insulating layer is divided into two separate films: a first insulating film (prepreg with reinforcing member) and a second insulating film (resin-only). This segmentation allows the reinforcing member to provide strength while the second film acts as an insulating barrier between the wiring layer and the reinforcing member, preventing contact and maintaining insulation reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second insulating film composed of only resin serves as an intermediary layer between the wiring layer and the reinforcing member in the first insulating film. This intermediate resin layer ensures that the wiring layer does not directly contact the reinforcing member, thereby maintaining insulation reliability while still allowing the reinforcing member to provide structural strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11152293B2Wiring board having two insulating films and hole penetrating therethrough

Publication Date: 2021.10.19 SHINKO ELECTRIC IND CO LTD

AI summary

A wiring board includes an insulating layer including a first insulating film provided with a first surface and a second surface that is opposite to the first surface, and composed of only resin, and a second insulating film provided with a first surface and a second surface that is opposite to the first surface, including a reinforcing member and resin, in which the reinforcing member is impregnated with the resin, and stacked on the first surface of the first insulating film such that the second surface of the second insulating film contacts the first surface of the first insulating film and the second surface of the first insulating film is exposed outside; and a first wiring layer embedded in the first insulating film, a predetermined surface of the first wiring layer being exposed from the second surface of the first insulating film.