Thermally Conductive Sheet Balancing Heat Transfer and Flexibility

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Solution Overview

Problem

Conventional thermally conductive sheets face challenges in achieving a balance between high thermal conductivity, low steady load value, and flexibility, which are essential for modern electronic components as they generate increasing heat and require efficient heat dissipation.

Innovation Solution

A thermally conductive sheet composed of a matrix resin and thermally conductive particles, with a polymer viscosity of 500 Pa·s or less after crosslinking, and a thermal conductivity of 2.0 W/m·K or more, featuring a high content of thermally conductive particles (200 parts by volume or more) to ensure flexibility and low load values, thereby improving adhesion and handleability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the content of thermally conductive particles is increased to improve thermal conductivity, then the thermal conductivity increases, but the steady load value increases and flexibility decreases

Engineering Contradiction:
Improvethermal conductivityVSAvoidflexibility
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

The invention changes the polymer viscosity parameter of the matrix resin component to 500 Pa·s or less after crosslinking reaction, which resolves the contradiction between thermal conductivity and flexibility. This specific viscosity parameter allows the material to maintain both high thermal conductivity (2.0 W/m·K or more) and low steady load value, enabling the sheet to follow the unevenness of electronic components while dissipating heat effectively.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite material system consisting of a matrix resin component and thermally conductive particles. The matrix resin component with controlled polymer viscosity (500 Pa·s or less) acts as a binder that holds the thermally conductive particles together, creating a composite structure that achieves both high thermal conductivity and flexibility. This composite approach allows the material to overcome the limitations of using only high particle content.

Inventive Principle:
Principle #40Composite materials

2Temperature

If the content of thermally conductive particles is increased to improve thermal conductivity, then the thermal conductivity increases, but the steady load value increases

Engineering Contradiction:
Improvethermal conductivityVSAvoidsteady load value
Core Design Contradiction:
TemperatureVSForce

Solution Approach 1:

The invention controls the polymer viscosity parameter of the matrix resin component to 500 Pa·s or less after crosslinking reaction, which effectively reduces the steady load value while maintaining high thermal conductivity. This parameter control allows the material to achieve a maximum load value of 100 kPa or more and a load value after 1 minute of more than 0 kPa and 100 kPa or less, resolving the contradiction between thermal conductivity and steady load value.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the polymer viscosity is reduced to improve flexibility and reduce steady load value, then the flexibility and handleability improve, but the structural integrity may deteriorate

Engineering Contradiction:
ImproveflexibilityVSAvoidstructural integrity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The invention optimizes the polymer viscosity parameter to a specific range (500 Pa·s or less) that balances flexibility and structural integrity. This controlled viscosity ensures the sheet can follow the unevenness of electronic components while maintaining sufficient structural strength to hold the thermally conductive particles together and function as a cohesive material.

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 thermally conductive sheet achieves high thermal conductivity, low steady load value, and flexibility, reducing the risk of damage to holding members and enhancing its ability to follow the unevenness of electronic components, while maintaining good handleability.

Implementation Method 1

A polymer viscosity of the matrix resin component after a crosslinking reaction in the absence of the thermally conductive particles is 500 Pa·s or less at 25°C

Methodology Applied
Scientific EffectCrosslinking reaction: Chemical Bonding

Implementation Method 2

A thermal conductivity of the thermally conductive sheet is 2.0 W/m·K or more

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3726573B1Heat conductive sheet and method for producing same
Publication Date: 2024.03.20 FUJI POLYMER INDUSTRIES CO LTD
  • EP3726573B1 patent drawingFigure 1
  • EP3726573B1 patent drawingFigure 2A~2B
  • EP3726573B1 patent drawing

AI summary

A thermally conductive sheet contains a matrix resin and thermally conductive particles. The content of the thermally conductive particles is 200 parts by volume or more with respect to 100 parts by volume of the matrix resin component. A polymer viscosity of the matrix resin component after a crosslinking reaction in the absence of the thermally conductive particles is 500 Pa·s or less at 25°C. A thermal conductivity of the thermally conductive sheet is 2.0 W/m·K or more. When the thermally conductive sheet with an initial thickness of 1.5 mm is compressed at a compression rate of 5.0 mm/min to measure a 50% compressive load value, the maximum load value is 100 kPa or more and the load value after 1 minute is more than 0 kPa and 100 kPa or less. With this configuration, the thermally conductive sheet has a high thermal conductivity, a low steady load value, and flexibility.