Prepreg Composite Structure for Thick Circuit Embeddability

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Solution Overview

Problem

Existing prepregs face challenges in embedding inner layer circuits with large conductor thickness due to increased resin layer thickness leading to cracking and peeling, which results in defects such as dents, and methods to improve moldability either increase weight or deteriorate heat dissipation.

Innovation Solution

A prepreg comprising two or more fiber substrate layers with one or more resin composition layers, where at least one resin composition layer has a fiber substrate layer on each surface, with a thickness ratio of 0.25 to 5, and including glass cloth and a thermosetting resin composition, to enhance embeddability and handling properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the thickness of the resin layer is increased to embed inner layer circuits with large conductor thickness, then the embeddability is improved, but cracks occur on the resin layer due to deformation when the prepreg is lifted up, causing peeling and defects

Engineering Contradiction:

Improveembeddability of inner layer circuitVSAvoidintegrity of resin layer

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses a composite structure consisting of a fiber substrate layer and a resin composition layer. The fiber substrate layer (glass cloth) provides mechanical strength and dimensional stability, while the resin composition layer provides embeddability. This composite structure allows the resin layer to be thick enough for good embeddability without causing cracking and peeling, as the fiber substrate reinforces the overall structure.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the content of resin component in the prepreg is increased to improve the embeddability of inner layer circuit, then the moldability is improved, but the resin component may fall off due to its weight

Engineering Contradiction:

Improveembeddability of inner layer circuitVSAvoidadhesion of resin component

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The patent creates a composite material where the resin composition layer is combined with the fiber substrate layer. The fiber substrate (glass cloth) acts as a reinforcement that prevents the resin component from falling off due to its own weight, while still maintaining high resin content for good embeddability. The fiber network within the resin layer provides structural support.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different properties to different parts of the prepreg: the resin composition layer has high resin content for embeddability, while the fiber substrate layer provides structural strength and prevents resin from falling off. Each layer has optimized local properties that complement each other.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If a large number of prepregs are laminated to improve the moldability, then the embeddability is improved, but the thickness of the entire substrate becomes large, causing increased weight and deteriorated heat dissipation properties

Engineering Contradiction:

Improveembeddability of inner layer circuitVSAvoidweight of substrate

Core Design Contradiction:

Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent uses a composite structure with fiber substrate and resin composition layers that achieves good embeddability in a single prepreg configuration. This eliminates the need to laminate multiple prepregs, thereby reducing the overall substrate thickness, weight, and improving heat dissipation properties while maintaining excellent moldability.

Inventive Principle:

Principle #40Composite materials

4Reliability

If the thickness of the conductor is increased to reduce electric resistance, then the electric resistance becomes smaller, but the thickness greatly changes between the portion where the conductor is present and the portion where the conductor is not present, causing difficulty in embeddability

Engineering Contradiction:

Improveelectric resistanceVSAvoidembeddability of inner layer circuit

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses a composite structure where the resin composition layer provides excellent moldability and embeddability. This allows the prepreg to conform to the varying thickness of the conductor (up to 200 μm or more) without creating voids or defects. The fiber substrate reinforces the structure to handle the thickness variations.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS10856423B2Prepreg, printed circuit board, semiconductor package, and method for producing printed circuit board

Publication Date: 2020.12.01 RESONAC CORP

AI summary

Provided are a prepreg including two or more fiber substrate layers and one or more resin composition layers, in which at least one of the one or more resin composition layers has a fiber substrate layer on each of both surfaces thereof, a printed circuit board using the prepreg and a method of producing the printed circuit board, and a semiconductor package.