Graphite Sheet Thermal Interface for Vacuum Heat Dissipation
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Solution Overview
Problem
Current thermal interface materials used in accelerator-type neutron generators face challenges such as poor thermal conductivity, risk of outgassing under ultrahigh vacuum conditions, and potential radioactivation, which can lead to heat shock and contamination, limiting their effectiveness in high-intensity beam applications.
Innovation Solution
A graphite sheet with a thickness of 9.6 μm to 50 nm and a density of at least 1.8 g/cm3, produced by thermally treating an aromatic polymer film, such as an aromatic polyimide, at an ultrahigh temperature of 2900°C or higher, offering exceptional thermal conductivity exceeding 1000 W/mK and resistance to high-temperature, high-intensity irradiation without outgassing or radioactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat release grease or phase change sheet is used as thermal interface material, then thermal conductivity is improved, but outgassing contaminates the interior of the apparatus under ultrahigh vacuum
Solution Approach 1:
The patent changes the material composition parameter from organic-based thermal interface materials to graphite-based material, which fundamentally alters the outgassing characteristics while maintaining high thermal conductivity. The graphite sheet is produced by thermal treatment of polymer films at temperatures of 2000°C or higher, transforming the material into a vacuum-compatible form that eliminates outgassing issues.
2Temperature
If TIM containing metal and inorganic filler is used, then thermal conductivity is improved, but filler scatters and contaminates the inside of beam line
Solution Approach 1:
The patent uses graphite as a composite material that combines the desirable properties of both organic materials (vacuum compatibility, no outgassing) and inorganic materials (high thermal conductivity). The graphite structure provides continuous thermal pathways without requiring separate filler particles, thereby eliminating filler scattering and contamination issues while achieving superior thermal conductivity of 1000 W/mK or higher.
3Ease of manufacture
If conventional thermal interface material is used, then ease of manufacture is maintained, but thermal conductivity is insufficient for high-intensity beam applications
Solution Approach 1:
The patent achieves high thermal conductivity by changing the microstructural parameters of the material through controlled thermal treatment. By heating polymer films to 2000°C or higher, the material transforms into graphite with highly ordered crystalline structure, achieving thermal conductivity of 1000 W/mK or higher. This process maintains ease of manufacture by starting with simple polymer film substrates that can be easily produced and handled.
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 sheet provides excellent thermal conductivity and chemical stability, preventing outgassing and radioactivation, thus enhancing heat release properties and withstanding prolonged exposure to high-intensity beams, expanding its application in high-vacuum and high-temperature environments.
Implementation Method 1
the graphite sheet can withstand irradiation conditions in which a high-intensity beam is used at a high temperature for a long period of time
Implementation Method 2
produced by thermally treating an aromatic polymer film, such as an aromatic polyimide, at an ultrahigh temperature of 2900°C or higher
Data Source
AI summary
A thermal interface material under a high vacuum condition includes a graphite sheet having a thickness of from 9.6 μm to 50 nm and a thermal conductivity in an a-b surface direction at 25° C. of not less than 1000 W/mK.