Graphite-Elastic Thermal Sheet for Uneven Joints
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Solution Overview
Problem
Current heat transfer materials, such as thermal greases and phase change sheets, have lower thermal conductivity than metals and fail to adequately reduce thermal resistance at joints with uneven surfaces, leading to increased thermal resistance due to gaps and insufficient adhesion.
Innovation Solution
A flexible sheet with alternately stacked graphite and elastic layers, where the graphite layers protrude and bend to cover the elastic layer ends, ensuring high thermal conductivity and contact with both the heating and radiating bodies, reducing thermal resistance and increasing heat conduction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hard heat transfer material, such as metal, is used at joint gap, then thermal conductivity is improved, but adhesion to uneven surfaces deteriorates and thermal resistance increases
Solution Approach 1:
The invention uses a composite material consisting of a flexible substrate containing graphite fibers or flake graphite combined with a filler. This composite structure integrates the high thermal conductivity of graphite with the flexibility and conformability of the substrate material, allowing the heat transfer sheet to simultaneously achieve high thermal conductivity and good adhesion to uneven surfaces.
Solution Approach 2:
The invention changes the physical state and properties of the heat transfer material by using a flexible substrate with specific mechanical properties (elongation at break of 100% or more) rather than rigid metal. This parameter change enables the material to deform and conform to uneven surfaces while maintaining high thermal conductivity through the graphite content.
2Reliability
If thermal grease or phase change sheet is used to fill joint gap, then adhesion to uneven surfaces is improved, but thermal conductivity deteriorates
Solution Approach 1:
The invention creates a composite heat transfer sheet combining a flexible substrate with graphite filler material. The substrate provides the filling capability and conformability to joint gaps, while the graphite filler (with thermal conductivity of 100 W/mK or more) provides high thermal conductivity, overcoming the limitation of pure grease or phase change materials.
Solution Approach 2:
The invention applies local quality by concentrating the high thermal conductivity function in the graphite filler regions while the substrate provides the filling and conforming function. This spatial differentiation of functions allows the material to simultaneously achieve good gap filling and high thermal conductivity.
3Temperature
If graphite fibers are orientated perpendicularly to joint plane, then bulk thermal conductivity is improved, but contact with joint surfaces deteriorates and thermal resistance increases
Solution Approach 1:
The invention uses flake graphite with a plate-like (curved/spheroidal) shape rather than straight perpendicular fibers. The flake structure can orient itself to contact the joint surfaces while maintaining good thermal conduction paths within the material, improving both surface contact and bulk thermal conductivity.
Solution Approach 2:
The invention changes the orientation and shape parameters of the graphite component from perpendicular fibers to flakes that can conform to surfaces. This parameter change enables the graphite to simultaneously achieve good surface contact and maintain high bulk thermal conductivity through its layered structure.
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 significantly reduces thermal resistance and enhances heat conduction efficiency by maintaining a high thermal conductivity path across the joint gap, even with uneven surfaces, and reduces contact thermal resistance.
Implementation Method 1
graphite layers and elastic layers are arranged alternately... one end of the graphite layer in its surface direction is in contact with a surface of the radiating body, and another end is in contact with a surface of the heating body
Data Source
AI summary
[Problem] To reduce thermal resistance between a heating body and a radiating body.[Solving Means] Provided is a sheet having a high thermal conductivity and flexibility, in which graphite layers and elastic layers are stacked alternately, and each of ends of the graphite layer in its surface direction or each of ends of a graphene protrudes from an end of the elastic layer and bends so as to cover at least a part of the end of the elastic layer. By placing a sheet of the present invention in a space (gap) between a heating body and a radiating body, thermal resistance at the gap, especially contact thermal resistance on a joint surface, can be reduced even in the case where flatness of a surface of the heating body or a surface of the radiating body is small.