Thermally Conductive Sheet With Oriented Carbon Fibers

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Solution Overview

Problem

Thermally conductive sheets with oriented carbon fibers face challenges in achieving high heat conductivity while maintaining electrical insulation and handleability, as the addition of an electrically insulating layer impairs heat conductivity and makes the surface hard and difficult to attach.

Innovation Solution

A thermally conductive sheet is created by stacking a carbon fiber oriented layer and an electrically insulating layer, where the carbon fiber layer has fibers oriented in the thickness direction within a polymer matrix, and the electrically insulating layer contains a filler dispersed in the polymer matrix, enhancing electrical insulation without significantly degrading heat conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electrically insulating layer is formed on a thermally conductive sheet with oriented carbon fibers, then electrical insulating property is improved, but heat conducting property is significantly impaired

Engineering Contradiction:

Improveelectrical insulating propertyVSAvoidheat conducting property

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent creates a composite material by integrating an electrically insulating layer onto a thermally conductive sheet with oriented carbon fibers. This composite structure allows the base layer to maintain high thermal conductivity while the insulating layer provides electrical isolation, resolving the contradiction between electrical insulation and heat conduction through material composition rather than separate components

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The electrically insulating layer is applied specifically to the surface of the thermally conductive sheet, creating a localized functional zone. The insulating property is concentrated where electrical isolation is needed (at the contact surface), while the bulk thermally conductive sheet retains its heat conduction capability, allowing different regions to optimize for different functions

Inventive Principle:

Principle #3Local quality

2Reliability

If an electrically insulating layer is formed on a thermally conductive sheet, then electrical insulating property is improved, but handleability deteriorates due to hard surface

Engineering Contradiction:

Improveelectrical insulating propertyVSAvoidhandleability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent modifies the physical and chemical parameters of the electrically insulating layer, specifically controlling its hardness, thickness, and surface characteristics. By adjusting these parameters, the layer maintains sufficient electrical insulation while achieving a softer, more compliant surface that improves handleability and conformability to mounting surfaces

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If flake graphite powder is used for heat conduction, then heat conducting property is improved, but electrical conductivity increases due to particle contact

Engineering Contradiction:

Improveheat conducting propertyVSAvoidelectrical conductivity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent changes the geometric parameter of the heat transfer material from flake-shaped graphite particles to fiber-shaped carbon fibers. This shape transformation fundamentally alters the contact behavior: fibers can be oriented to minimize end-to-end contact (reducing electrical conductivity) while maintaining thermal conduction pathways through their elongated structure, thus decoupling thermal and electrical conduction properties

Inventive Principle:

Principle #35Parameter changes

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 thermally conductive sheet with both high heat conductivity and electrical insulation, improved handleability, and effective adhesion to objects, reducing thermal resistance and maintaining flexibility.

Implementation Method 1

the carbon fiber oriented thermally conductive layer containing a carbon fiber powder, which has a fiber axis oriented in a sheet thickness direction and is contained in a polymer matrix

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the electrically insulating thermally conductive layer having a heat conducting property and an electrical insulating property

Methodology Applied

Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentUS10591229B2Thermally conductive sheet

Publication Date: 2020.03.17 SEKISUI POLYMATECH CO LTD

AI summary

A thermally conductive sheet is obtained by stacking a carbon fiber oriented thermally conductive layer and an electrically insulating thermally conductive layer, the carbon fiber oriented thermally conductive layer containing a carbon fiber powder, which has a fiber axis oriented in a sheet thickness direction and is contained in a polymer matrix, the electrically insulating thermally conductive layer having a heat conducting property and an electrical insulation property and containing an electrically insulating thermally conductive filler dispersed in a polymer matrix. This thermally conductive sheet has both a high heat conducting property and an electrical insulating property, is easy to be fixed to an object to be attached, and has excellent handleability.