Patterned Flexible Graphite Sheets for Air-Free Densification

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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 the flexible graphite sheet material on at least one major surface before densification or lamination to facilitate air removal and alter the orientation of graphite flakes, thereby increasing through-plane conductivity and reducing thermal anisotropy, and using patterned dies or rollers to create specific patterns that enhance flexibility and surface area for improved heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If flexible graphite is compressed to increase density, then density improves, but air becomes trapped causing blistering and delamination

Engineering Contradiction:

ImprovedensityVSAvoidblistering and delamination

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The graphite material is patterned with channels and cavities before compression to create predetermined pathways for air escape. This preliminary structuring prevents air trapping during subsequent compression, allowing high density to be achieved without blistering or delamination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention introduces a controlled porous structure with channels and cavities into the graphite material. These pores serve as air escape routes during compression, enabling the material to achieve high density while maintaining structural integrity and avoiding defects like blistering.

Inventive Principle:

Principle #31Porous materials

2Ease of operation

If resin is used to fill pores during impregnation, then flexibility improves, but electrical conductivity decreases in impregnated regions

Engineering Contradiction:

ImproveflexibilityVSAvoidelectrical conductivity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The graphite material is selectively patterned with channels and cavities in specific regions where flexibility is needed, rather than uniformly impregnating the entire material with resin. This localized approach provides flexibility enhancement only where required, preserving electrical conductivity in other regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of filling all pores with resin, the invention maintains a controlled porous structure with channels and cavities that are selectively filled or left open. This allows the material to achieve flexibility through controlled porosity rather than complete resin impregnation, preserving electrical conductivity pathways.

Inventive Principle:

Principle #31Porous materials

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 process enhances the density, homogeneity, and flexibility of graphite materials, significantly increasing through-plane thermal conductivity, reducing the tendency for blistering and delamination, and improving thermal management efficiency in applications like heat sinks and thermal interfaces.

Implementation Method 1

the patterning is selected to facilitate the removal of air from the flexible graphite sheet material during the compression step

Methodology Applied

Scientific EffectAir removal through patterning:

Implementation Method 2

compressing the patterned graphite sheet material to produce densified flexible graphite sheet material

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

alter the orientation of graphite flakes within the sheet material so that more of them are oriented perpendicular to the plane of the material

Methodology Applied

Scientific EffectOrientation change:

Implementation Method 4

The thermal properties of flexible conventional flexible graphite are similarly highly anisotropic with the in-plane thermal conductivity being many times greater than the through-plane conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20240021495A1Apparatus and Methods for Processing Exfoliated Graphite Materials

Publication Date: 2024.01.18 AFFINITY GRAPHITE LTD

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.