Multilayer Wiring Substrate With Undulated Interface

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Solution Overview

Problem

Conventional multilayer wiring substrates face issues with mechanical strength due to differences in thermal expansion coefficients and elastic moduli, leading to difficulties in mounting surface mount components and potential peeling of surface layers.

Innovation Solution

A plate-shaped multilayer wiring substrate is developed with at least two resin layers and a front surface layer having a higher elastic modulus, featuring a joint interface with projections and depressions, manufactured through a process involving hot pressing and thermosetting resin with glass fillers to enhance mechanical strength and thermal stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resin sheets are selected with priority given to electrical properties, then electrical properties are improved, but mechanical properties are lowered

Engineering Contradiction:

Improveelectrical propertiesVSAvoidmechanical properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention uses a composite structure consisting of a resin layer and a reinforcement sheet with different material properties. The resin layer provides electrical insulation and conductivity, while the reinforcement sheet provides mechanical strength. This composite approach allows both electrical and mechanical properties to be optimized simultaneously without compromising either aspect.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If resin sheets having a low elastic modulus are used, then ease of deformation is improved, but mounting of surface mount components becomes difficult

Engineering Contradiction:

Improvedeformation easeVSAvoidmounting difficulty

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The combination of resin layer and reinforcement sheet creates a composite structure where the resin provides deformability for easy assembly while the reinforcement sheet provides rigidity for stable component mounting. This dual-material approach resolves the contradiction between ease of deformation and ease of manufacture.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If a front surface sheet having a different elastic modulus is stacked on resin sheets, then adaptability is improved, but mechanical strength is lowered due to difference in thermal expansion coefficient

Engineering Contradiction:

Improveelastic modulus variationVSAvoidmechanical strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The invention applies local quality by using a reinforcement sheet with specific material properties (high elastic modulus and matched thermal expansion coefficient) at the interface between layers. This localized reinforcement addresses the thermal expansion mismatch issue while maintaining the adaptability benefits of using sheets with different elastic moduli.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure of resin layer plus reinforcement sheet provides both adaptability through material selection and mechanical strength through the reinforcement sheet's high stiffness and thermal expansion matching, resolving the contradiction between adaptability and strength.

Inventive Principle:

Principle #40Composite materials

4Ease of manufacture

If a flat surface is used at the joint interface, then manufacturing simplicity is improved, but reliability is lowered due to peeling under thermal stress

Engineering Contradiction:

Improvejoint interface simplicityVSAvoidpeeling resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention uses an undulated surface with curved profiles instead of a flat surface at the joint interface. This curved geometry increases the bonding area and provides mechanical interlocking, which significantly improves peeling resistance under thermal stress while maintaining manufacturing feasibility through molding processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a highly reliable multilayer wiring substrate with improved mechanical strength and thermal stability, reducing the likelihood of peeling and enabling effective mounting of surface mount components.

Implementation Method 1

a curing reaction is performed on the thermosetting resin by heating

Methodology Applied

Scientific EffectCuring reaction: Chemical Bonding

Implementation Method 2

performing pressing under pressure from above the front surface layer using a flat surface in a heated state

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS10959327B2Multilayer wiring substrate

Publication Date: 2021.03.23 MURATA MFG CO LTD

AI summary

A plate-shaped multilayer wiring substrate includes at least two resin layers stacked on top of each other and each including an insulating base and a conductive pattern provided on the insulating base, and a front surface layer joined onto the resin layers stacked. The front surface layer has a higher elastic modulus than an elastic modulus of the insulating bases. A joint interface between the resin layers and the front surface layer includes projections and depressions. Also, a method for manufacturing the plate-shaped multilayer wiring substrate includes a step of stacking, on top of resin layers, a front surface layer having a higher elastic modulus than an elastic modulus of the resin layers, and a step of performing pressing under pressure from above the front surface layer by using a flat surface in a heated state to join the resin layers and the front surface layer.