Clamped Pyrolytic Graphite Heat Spreader for Weight Reduction
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Solution Overview
Problem
Conventional heat spreaders using monolithic copper spreaders are heavy, which results in a weighty assembly that is inefficient for heat transfer and spreading.
Innovation Solution
A heat spreader comprising compressible and rigid pyrolytic graphite sheets interleaved and clamped together, providing high in-plane thermal conductivity (>1000 W/m-K) with densities less than 10% of copper, interposed between a module and a cold plate to transfer and spread heat, while a clamp compresses the sheets to optimize thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If monolithic copper spreaders are used, then heat spreading performance is achieved, but weight increases significantly
Solution Approach 1:
The patent uses a composite structure consisting of multiple pyrolytic graphite sheets (both compressible and rigid types) interleaved with foam material and bonded together. This composite construction achieves high thermal conductivity comparable to copper while reducing weight by 20-30%, as the graphite sheets provide thermal pathways without the density of copper material.
Solution Approach 2:
The heat spreader is divided into multiple discrete graphite sheets rather than using a monolithic copper block. The segmented structure includes compressible graphite sheets, rigid graphite sheets, and foam material layers that are bonded together. This segmentation allows for weight reduction while maintaining thermal performance through the layered thermal conduction paths.
2Weight of moving object
If pyrolytic graphite sheets are used instead of copper, then weight is reduced, but structural rigidity may be compromised
Solution Approach 1:
The patent employs different types of graphite sheets with different properties in specific locations: compressible graphite sheets in certain layers and rigid graphite sheets in other layers. This local differentiation allows the structure to achieve both weight reduction and adequate structural support, with rigid sheets providing strength where needed and compressible sheets providing thermal pathways in other areas.
Solution Approach 2:
The composite construction combines multiple materials including compressible graphite, rigid graphite, and foam material bonded together with adhesive. This composite approach provides structural rigidity through the rigid graphite sheets and foam support while maintaining low weight, overcoming the limitation of using graphite alone.
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 solution achieves heat spreading performance comparable to copper heat spreaders with a significant reduction in weight (20-30% less) and eliminates the need for epoxy-based materials, enhancing thermal performance and reducing weight.
Implementation Method 1
The heat spreading element is interposed between the module and the cold plate to provide for the transfer of heat from the module to the cold plate in a first direction
Implementation Method 2
to spread the heat out in a second direction transverse with respect to the first direction
Implementation Method 3
the clamp is disposed and configured to clamp the heat spreading element between the module and the cold plate and to compress the compressible pyrolytic graphite sheets and the rigid pyrolytic graphite sheets in the first direction
Data Source
AI summary
A heat spreading element is provided. The heat spreading element includes compressible pyrolytic graphite sheets and rigid pyrolytic graphite sheets interleaved with the compressible pyrolytic graphite sheets.