Flexible Heat Conductive Layer for Thermal Interface Management
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Solution Overview
Problem
Current heat transfer systems for electronic devices face challenges in efficiently managing thermal dissipation, particularly in high-density applications where thin bond lines and thermal interface materials lead to temperature drops and limitations in size, weight, and power considerations, with existing solutions like graphite composites and heat pipes showing degradation over time due to thermal cycling and orthotropic conductivity.
Innovation Solution
A heat transfer assembly comprising a flexible, heat conductive layer with a compressible matrix and phase change material, thermally coupled to both the heat generating component and the heat sink body, utilizing alignment features like magnetic bodies or fasteners for secure and adjustable thermal contact, enabling multi-path heat transport and adaptable mechanical retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin bond lines of thermal interface material are used to reduce space between component and heat sink, then space is reduced, but temperature drops increase due to poor thermal conduction
Solution Approach 1:
The patent changes the physical state and properties of the thermal interface material by using a compressible layer that can be compressed to a thin state while maintaining thermal conduction. The compressible layer is compressed between the heat generating component and heat sink, creating a thin bond line that still provides adequate thermal coupling without the temperature drops associated with traditional thin TIMs.
Solution Approach 2:
The patent employs a composite structure consisting of a compressible layer with flexible heat conductive material integrated within it. This composite material combines the compressibility and conformability of elastomeric materials with the high thermal conductivity of materials like graphite or metal foils, achieving both thin profile and effective heat transfer.
2Temperature
If graphite composites and heat pipes are used to spread heat efficiently, then heat conduction is improved, but degradation occurs over time due to thermal cycling
Solution Approach 1:
The compressible layer serves as a cushioning element that accommodates thermal expansion and contraction during thermal cycling. Its elastic properties allow it to deform and recover, preventing the degradation and failure that occurs in rigid thermal interface solutions when subjected to repeated thermal stress.
Solution Approach 2:
The patent changes the mechanical properties of the thermal interface by using a compressible, elastomeric material that can dynamically adjust to thermal expansion and contraction. This flexibility prevents the stress concentration and material degradation that plagues rigid thermal interface solutions under thermal cycling conditions.
3Volume of moving object
If two-piece modular heat sinks with targeted heat pipes are used, then thermal interface material bond lines are reduced, but they do not fit standard 6U or 3U module sizes
Solution Approach 1:
The compressible layer with integrated heat conductive material serves multiple functions: it provides thermal conduction, acts as a mechanical cushion, accommodates misalignment, and adapts to different form factors. This universal solution can be applied to various standard module sizes including 6U and 3U configurations, replacing the need for application-specific modular heat sink designs.
Solution Approach 2:
The patent uses a flexible compressible layer that can be manufactured in various sizes and configurations to fit standard module form factors. This flexible approach allows the same basic design to adapt to different dimensional requirements, including standard 6U and 3U rack mount sizes, without requiring custom modular heat sink assemblies.
4Temperature
If heat sink is directly bolted to printed circuit board, then thermal contact is improved, but bond lines become less than 1 mil with limited adjustability
Solution Approach 1:
The compressible layer introduces dynamics to the thermal interface by allowing compression and deformation. This dynamic capability enables adjustment of the thermal contact quality through compression force, allowing operators to optimize thermal coupling by applying appropriate compression during assembly, unlike rigid direct-bolted configurations.
Solution Approach 2:
The patent changes the mechanical state of the thermal interface by using a compressible material that can be compressed to achieve optimal thermal contact. This allows adjustment of the contact pressure and thermal coupling quality, providing ease of operation during assembly while maintaining excellent thermal contact, unlike fixed rigid connections.
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
This solution significantly reduces thermal resistance by up to 79% compared to traditional TIMs, providing improved thermal conductivity, flexibility, and resistance to fatigue through the compressible layer's damping effect and phase change material, while accommodating disparate thermal expansion rates and maintaining structural alignment.
Implementation Method 1
a compressible layer is between the first and second portions. The compressible layer may comprise a compressible matrix, and a phase change material may be within the compressible matrix.
Implementation Method 2
The flexible, heat conductive layer may comprise at least one of graphite and copper.
Data Source
AI summary
An electronic device may include a circuit board, a heat generating component carried by the circuit board, a heat sink body, and a heat transfer assembly between the heat generating component and the heat sink body. The heat transfer assembly may include a flexible, heat conductive layer having a first portion in thermal contact with the heat generating component and a second portion in thermal contact with the heat sink body. The first and second portions are thermally coupled, and a compressible layer is between the first and second portions of the flexible, heat conductive layer.