Two-Layer Synthetic Diamond Heat Spreader for Thermal Management
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Solution Overview
Problem
Current thermal management configurations for wide band gap electronic devices and extreme optical applications are limited by high power dissipation and localized heat generation, with conventional cooling techniques imposing a ceiling on device performance and reliability, and the use of isotopically purified synthetic diamond materials is costly due to expensive carbon sources and nitrogen impurities in CVD synthesis.
Innovation Solution
A synthetic diamond heat spreader with a two-layer structure, where the base support layer has a lower thermal conductivity (1000-1800 W/mK) and the surface layer has a higher thermal conductivity (1900-2800 W/mK), achieved by controlling nitrogen concentration during CVD growth, allowing for improved thermal performance without the high cost of isotopically purified carbon sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If isotopically purified carbon sources are used to reduce 13C content in synthetic diamond materials, then bulk thermal conductivity increases by nearly a factor of two, but fabrication cost increases significantly
Solution Approach 1:
The patent applies local quality by creating a two-layer diamond structure where only the surface layer (in contact with the heat generating component) is isotopically purified to reduce 13C content and maximize thermal conductivity, while the bulk material uses natural abundance carbon sources. This localized application of isotopic purification maintains high thermal conductivity at the critical interface while avoiding the prohibitive cost of purifying the entire bulk material.
Solution Approach 2:
The patent segments the diamond heat spreader into two distinct layers: a surface layer grown from isotopically purified carbon sources with high thermal conductivity, and a bulk layer grown from natural abundance carbon sources with lower thermal conductivity. This segmentation allows the system to achieve high overall thermal performance while significantly reducing fabrication costs compared to uniform isotopic purification.
2Reliability
If conventional cooling techniques are used for thermal management, then device performance is maintained at current levels, but heat dissipation capability is limited by ceiling effects
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional cooling materials (metals, ceramics) to synthetic diamond with exceptionally high thermal conductivity (up to 4000 W/mK in isotopically purified material). This dramatic change in the thermal conductivity parameter enables heat dissipation capabilities far exceeding current cooling techniques, allowing wide band gap devices to operate at higher power densities without thermal runaway.
3Temperature
If nitrogen content is reduced in diamond surface layer, then thermal conductivity increases, but manufacturing complexity increases due to controlled CVD growth requirements
Solution Approach 1:
The patent segments the CVD growth process into two stages: first growing a bulk diamond layer from natural abundance carbon sources, then growing a surface layer from isotopically purified carbon sources with controlled nitrogen content. This segmentation of the manufacturing process makes the complex isotopic purification and controlled growth requirements manageable by isolating them to only the surface layer formation step.
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 two-layer synthetic diamond heat spreader provides enhanced thermal conductivity and reduced costs, achieving thermal performance comparable to uniformly high thermal conductivity diamond heat spreaders while offering significant material cost reductions and increased production capacity.
Implementation Method 1
The thermal performance of a particular synthetic diamond material will depend on its macro, micro, and nano-scale structure. Factors that contribute to thermal performance are those that lead to scattering of phonons within the synthetic diamond material
Implementation Method 2
various grades of synthetic diamond material grown by chemical vapour deposition (CVD) are already commercially available for thermal heat spreading applications
Data Source
AI summary
A synthetic diamond heat spreader that includes a first layer of synthetic diamond material forming a base support layer and a second layer of synthetic diamond material disposed on the first layer of synthetic diamond material and forming a diamond surface layer. The diamond surface layer has a thickness equal to or less than a thickness of the base support layer. The diamond surface layer has a nitrogen content less than that of the base support layer. The nitrogen content of the diamond surface layer and the diamond support layer is selected such that the thermal conductivity of the base support layer is in a range 1000 W/mK to 1800 W/mK and the thermal conductivity of the surface support layer is in a range 1900 W/mK to 2800 W/mK.