Self-Orienting Graphite Platelets for Thermal Paste
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Solution Overview
Problem
Traditional cooling methods for computer chips, which rely on thermal conductivity of gap filling materials, are inadequate for effectively managing the increased heat generated by higher power densities, leading to reliability, performance, and lifetime concerns due to high chip operating temperatures.
Innovation Solution
A thermally-conductive paste comprising anisotropic graphite platelets oriented with their basal plane perpendicular to the heat source and sink, combined with a liquid medium such as polyalphaolefin oil or gallium/indium eutectic, and coated with metals like copper or gold to enhance conductivity and compatibility, ensuring maximum heat transfer perpendicular to the planes of the heat source and sink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cooling methods with conventional thermal paste are used, then the cooling system is simple and easy to manufacture, but the thermal conductivity is insufficient to manage high power density heat
Solution Approach 1:
The patent uses a composite material consisting of anisotropic graphite platelets suspended in a liquid carrier medium. The graphite platelets provide high thermal conductivity along their basal planes, while the liquid medium provides wetting and filling properties. This composite structure achieves superior thermal conductivity compared to conventional thermal paste while maintaining ease of application.
Solution Approach 2:
The patent exploits the anisotropic thermal conductivity of graphite platelets by orienting their basal planes perpendicular to the heat flow direction. This creates local regions of high thermal conductivity exactly where needed for heat transfer from the heat source to the heat sink, rather than using isotropic materials with uniform but lower conductivity in all directions.
2Reliability
If graphite platelets are oriented with basal plane perpendicular to heat source and sink, then maximum heat transfer is achieved, but the paste formulation and application process becomes more complex
Solution Approach 1:
The patent employs self-aligning graphite platelets that automatically orient themselves perpendicular to the heat source and sink surfaces when the paste is applied and subjected to compression. This self-alignment mechanism eliminates the need for complex external alignment equipment or multi-step manufacturing processes, achieving maximum heat transfer rate through the inherent properties of the platelet geometry and application method.
Solution Approach 2:
The patent changes the physical state of the thermal interface material from a conventional solid or semi-solid paste to a suspension of platelet particles in a liquid carrier. This parameter change allows the platelets to move and self-align during application, then remain fixed in the optimal orientation once the paste sets, achieving high heat transfer without complex alignment procedures.
3Productivity
If higher power density is used in computer chips, then circuit integration and processing power increase, but heat generation increases leading to reliability and lifetime concerns
Solution Approach 1:
The patent introduces an intermediary thermal interface material consisting of anisotropic graphite platelet suspension that mediates heat transfer between the chip heat source and the heat sink. This intermediary provides a high-conductivity thermal pathway that efficiently removes heat generated by high-power-density circuits, preventing excessive temperature rise that would otherwise reduce chip reliability and lifetime.
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 significantly improves thermal conductivity by aligning the high-conductivity basal plane of graphite platelets with the direction of heat flow, effectively managing heat transfer and reducing chip operating temperatures, thereby enhancing reliability and performance.
Implementation Method 1
platelets of a material having a basal plane in a z-direction with a first length and a platelet plane having second and third lengths in an x- and a y-direction respectively... the basal plane defines the direction of maximal thermal conductivity
Data Source
AI summary
The present invention relates generally to thermally-conductive pastes for use with integrated circuits, and particularly, but not by way of limitation, to self-orienting microplates of graphite.