Patterned Flexible Graphite Sheets for Air Release and Heat Conduction
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Solution Overview
Problem
Flexible graphite materials used in thermal management applications face issues such as anisotropic thermal and electrical conductivity, air trapping during compression leading to blistering and delamination, and non-uniform properties, which affect their performance and homogeneity.
Innovation Solution
Patterning of flexible graphite sheet material on at least one major surface to facilitate air removal during densification and lamination, and to alter the orientation of graphite flakes for improved through-plane conductivity, flexibility, and reduced thermal anisotropy, using methods like calendering, die pressing, and embossing with patterns such as cross-hatched diamond or button patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If flexible graphite is compressed to increase density, then density improves, but air trapping causes blistering and delamination
Solution Approach 1:
The graphite material is pre-patterned with channels and cavities before compression to create predetermined air escape pathways. This preliminary structuring ensures that air can be systematically removed during subsequent compression without causing blistering or delamination, resolving the contradiction between achieving high density and preventing defects.
Solution Approach 2:
The invention utilizes a porous patterned structure with controlled channels and cavities that allow air to escape during compression. The porous design provides dedicated pathways for gas removal while maintaining the ability to achieve high density in the final compressed product, eliminating the harmful effect of trapped air.
2Ease of manufacture
If graphite flakes are oriented parallel to surfaces for easy formation, then ease of manufacture improves, but through-plane electrical and thermal conductivity deteriorate
Solution Approach 1:
The invention applies different flake orientations in different regions of the graphite material. Graphite flakes are oriented parallel to surfaces in regions where ease of manufacture is prioritized, while in specific regions (such as through-plane contact areas), flakes are oriented perpendicular to surfaces to maximize electrical and thermal conductivity in those directions.
Solution Approach 2:
The graphite material is constructed as a composite with multiple flake orientation zones. By combining regions with parallel-oriented flakes (for manufacturability) and regions with perpendicular-oriented flakes (for conductivity), the material achieves both ease of manufacture and reliable through-plane conductivity in different locations.
3Ease of operation
If resin is added to improve flexibility and fill pores, then flexibility improves, but electrical conductivity deteriorates
Solution Approach 1:
The invention extracts the need for resin by providing flexibility through an alternative mechanism. Instead of using resin to fill pores and provide flexibility, the material uses a controlled porous structure with channels that allows the graphite itself to provide flexibility while maintaining electrical conductivity through the graphite network.
Solution Approach 2:
The controlled porous structure with channels and cavities provides flexibility without requiring resin impregnation. The porous design allows the material to bend and flex while maintaining continuous graphite pathways for electrical conduction, eliminating the trade-off between flexibility and conductivity.
4Quantity of substance
If compression is applied to densify the material, then density improves, but non-uniform properties and delamination worsen
Solution Approach 1:
The material is pre-patterned with a systematic network of channels and cavities before compression. This preliminary structuring creates predetermined pathways for uniform densification, ensuring that compression forces are distributed evenly throughout the material and preventing localized delamination or non-uniform properties.
Solution Approach 2:
The controlled porous pattern provides a framework that guides uniform compression throughout the material. The channels and cavities act as stress distribution elements that prevent localized densification issues, ensuring uniform properties are achieved during the compression process.
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 patterning methods enhance the density, homogeneity, and thermal properties of flexible graphite, reducing anisotropy and improving its ability to dissipate heat efficiently, while preventing blistering and delamination, resulting in more uniform and effective thermal management solutions.
Implementation Method 1
compressing the patterned graphite sheet material to produce densified flexible graphite sheet material, wherein the patterning is selected to facilitate the removal of gas from the flexible graphite sheet material during the compression step
Implementation Method 2
compressing the patterned graphite sheet material to produce densified flexible graphite sheet material
Implementation Method 3
the patterning is selected to alter the orientation of graphite flakes within the sheet material so that more of them are oriented perpendicular to the plane of the material
Implementation Method 4
compressing the patterned graphite sheet material to produce densified flexible graphite sheet material
Data Source
AI summary
Methods and apparatus for processing flexible graphite sheet material involve patterning the material, on at least one major surface, prior to further processing of the material such as densification, lamination, folding or shaping into three-dimensional structures. For densification and lamination, the patterning is selected to facilitate the removal of air from the flexible graphite sheet material during the densification and lamination process. For folding or shaping, the patterning is selected to render the graphite sheet material more flexible. In some embodiments, methods for increasing the through-plane conductivity of flexible graphite sheet material are employed. Integrated heat removal devices include sheets of graphite material that have been selectively patterned in different regions to impart desirable localized properties to the material prior to it being shaped or formed into an integrated heat removal device. Coatings and/or resin impregnation can also be used to impart desirable properties to the material or device.