Graphite Article Compressibility Thermal Impedance
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Solution Overview
Problem
Conventional graphite articles for thermal management systems face limitations in reducing thermal impedance and enhancing in-plane thermal conductivity, particularly when subjected to increased contact pressure, which affects their efficiency in heat dissipation.
Innovation Solution
A graphite article with a thickness of at least 100 microns and a density less than 1.00 g/cc, exhibiting compressibility of at least 3% at 100 KPa, and featuring a resistivity of less than 0.019 °C/W at 200 KPa, which can be compressed without damage, thereby reducing thermal impedance and increasing in-plane thermal conductivity as contact pressure increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the graphite article is minimized to reduce thermal impedance, then the thru-body thermal impedance decreases, but the compressibility and contact resistance performance deteriorate at lower contact pressures
Solution Approach 1:
The patent changes the physical parameters of graphite by introducing dopants (such as iodine, sulfur, or metals) to modify the electrical and thermal conductivity properties. This allows the graphite to achieve low contact resistance without requiring minimal thickness, thus resolving the contradiction between thermal impedance reduction and contact resistance performance.
Solution Approach 2:
The patent creates composite graphite materials by combining graphite with dopants or coatings (such as metal particles, carbon nanotubes, or graphene). These composite structures provide both the compressibility needed for good contact and the thermal conductivity required for low thermal impedance, simultaneously addressing both requirements.
2Temperature
If the density of graphite is increased to improve thermal conductivity, then the thermal management performance improves, but the compressibility decreases
Solution Approach 1:
The patent applies local quality by creating regions of different density and composition within the graphite article. The surface regions may have higher dopant concentration for low contact resistance, while the bulk maintains appropriate density for thermal conductivity. This localized differentiation allows both high thermal conductivity and good compressibility to coexist.
Solution Approach 2:
The patent utilizes porous or foamed graphite structures that provide high surface area and compressibility while maintaining good thermal conductivity through the porous network. The controlled porosity allows the material to compress easily for good contact while still providing effective heat dissipation pathways.
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 graphite article achieves a significant reduction in total thermal impedance and an increase in in-plane thermal conductivity with increased contact pressure, making it more effective in thermal management systems by maintaining structural integrity and enhancing heat dissipation capabilities.
Implementation Method 1
graphite articles which may have applications in thermal management systems... dissipation of heat in the z direction away from the heat source
Implementation Method 2
spreading of heat in x-y direction away from a hot spot exhibited on the heat source
Data Source
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Figure 5a~5c
AI summary
A graphite article which can be compressed by more three (3%) percent at a contact pressure of 100 KPa or less without damaging the graphite article reducing the thermal impedance exhibited by the article. Also a graphite article comprising graphitized polymer having a thickness of at least 75 microns. Preferably the graphite has a density of less than 1.50 g/cc and a compressibility of more than 3% at a contact pressure of 100 KPa. Also the article has a generally sheet like shape. These articles may be used in a thermal management system to dissipate heat from a heat source.