Carbon Shield Layer Module Board Thermal Expansion

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Solution Overview

Problem

Existing circuit modules with shield layers made of conductive resins like Ag or Cu suffer from interference with electronic components, leading to deteriorated module characteristics due to mismatched thermal expansion coefficients and high conductivity, which affects adhesion and mechanical strength.

Innovation Solution

A module board design featuring a shield layer made of a resin film with carbon as the conductive component, combined with an SiO2-filled sealing resin, which has a lower thermal expansion coefficient and conductivity than traditional materials, reducing interference and improving adhesion and mechanical strength while lowering costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a shield layer containing Ag or Cu filler is used, then shield characteristics against external interfering waves are improved, but interference with electronic components increases and module characteristics are deteriorated

Engineering Contradiction:

Improveshield characteristicsVSAvoidinterference with electronic components

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent changes the conductivity parameter of the shield layer by replacing Ag or Cu filler with carbon filler, which has lower conductivity. This reduces the capacitive effect between the shield layer and electronic components while maintaining sufficient shield characteristics against external interfering waves.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite material consisting of carbon filler dispersed in a resin matrix to form the shield layer. This composite structure provides both the shielding function and the desired electrical properties (lower conductivity) to minimize interference with electronic components.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If a shield layer containing Ag or Cu filler is used, then shield characteristics are improved, but adhesion strength between shield layer and sealing resin is reduced

Engineering Contradiction:

Improveshield characteristicsVSAvoidadhesion strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent changes the thermal expansion coefficient parameter of the shield layer by using carbon filler, which has a thermal expansion coefficient closer to that of the sealing resin than Ag or Cu. This reduces thermal stress at the interface and improves adhesion strength between the shield layer and sealing resin.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If Ag or Cu filler is used in the shield layer, then conductivity is improved, but weight increases and mechanical strength against falls is reduced

Engineering Contradiction:

ImproveconductivityVSAvoidmechanical strength against falls

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces expensive and heavy metal fillers (Ag, Cu) with carbon filler, which is lighter and provides sufficient conductivity for the shield layer application. This reduces the weight of the module board and improves its mechanical strength against falls while maintaining adequate electrical conductivity for shielding purposes.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 carbon-based shield layer effectively suppresses interference with electronic components, enhances adhesion, and improves module characteristics by matching thermal expansion coefficients with the sealing resin, resulting in better shield performance and increased mechanical strength while reducing weight and cost.

Implementation Method 1

the carbon that is contained in the shield layer has a conductivity that is lower than the conductivities of Ag and Cu

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the thermal expansion coefficient of the carbon contained in the shield layer is closer to the thermal expansion coefficient of the sealing resin compared to the thermal expansion coefficients of Ag and Cu

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9756718B2Module board

Publication Date: 2017.09.05 MURATA MFG CO LTD

AI summary

A module board includes a base substrate. Electronic components are mounted on a first principal surface of the base substrate. The mounted electronic components are sealed by a sealing resin containing an SiO2 filler. A top surface and side surfaces of the sealing resin are covered with a shield layer containing a carbon filler, which is flat powder, as a conductive component. A terminal electrode is formed on a second principal surface of the base substrate that is disposed opposite to the first principal surface of the base substrate.