Card Guide Thermal Interface for Conduction Cooling

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Solution Overview

Problem

Conventional conduction-cooled circuit card assemblies experience high thermal resistance at interfaces, leading to temperature rises that can render them unusable in high-power applications due to inefficient heat dissipation, especially when using dry-contact interfaces and wedge clamps.

Innovation Solution

Incorporating controlled-volume cavities in card guides with thermal interface materials (TIMs) that are compressed by wedge clamps to form multiple conduction cooling paths, optimizing heat transfer between circuit cards and the enclosure while maintaining structural integrity and allowing for repeated insertion/removal cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If dry-contact interfaces are used between circuit cards and card cage, then structural simplicity and ease of assembly are improved, but thermal resistance increases leading to overheating

Engineering Contradiction:

Improveinterface structureVSAvoidthermal resistance

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

A thermal interface material (TIM) is introduced as an intermediary substance between the circuit card and card cage surfaces. The TIM fills micro-gaps and irregularities at the interface, providing a continuous thermal conduction path that significantly reduces thermal resistance compared to direct dry-contact interfaces, while maintaining the overall simplicity of the assembly structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The interface structure is modified by adding a controlled-volume cavity that allows precise control of TIM compression. By adjusting the cavity volume and compression force, the thermal contact pressure and thermal resistance can be optimized to achieve the desired thermal performance without compromising structural simplicity.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If wedge clamps are used to compress TIM for improving heat transfer, then thermal resistance decreases, but structural complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidassembly complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The card guide is segmented to include an integrated controlled-volume cavity, separating the TIM containment function from the overall assembly complexity. This segmentation allows the TIM to be precisely positioned and compressed without requiring complex external mechanisms, simplifying manufacturing while maintaining effective heat transfer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The wedge clamp mechanism serves multiple functions: it secures the circuit card in place and simultaneously compresses the TIM to optimize thermal contact. This multi-functionality reduces the need for separate compression mechanisms, maintaining ease of manufacture while achieving improved heat transfer through controlled TIM compression.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If repeated insertion and removal cycles are allowed, then adaptability and ease of operation are improved, but thermal interface degradation and foreign debris generation occur

Engineering Contradiction:

Improverepeated insertion/removalVSAvoidthermal interface integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The controlled-volume cavity is designed with appropriate clearance and compression characteristics to accommodate repeated insertion and removal cycles. The cavity provides a cushioning effect that maintains consistent TIM compression throughout operational cycles, preventing interface degradation and avoiding foreign debris generation while enabling easy card replacement.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Temperature

If controlled-volume cavities with TIM are implemented, then thermal resistance is reduced, but device complexity and manufacturing precision requirements increase

Engineering Contradiction:

Improvethermal resistanceVSAvoidcavity volume control

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The controlled-volume cavity is designed with specific dimensional parameters that can be manufactured using standard tolerances. By optimizing the cavity volume and shape, the design achieves effective TIM compression and thermal contact without requiring excessive manufacturing precision, balancing thermal performance with manufacturability.

Inventive Principle:

Principle #35Parameter changes

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

Significantly reduces thermal resistance at interfaces, enhancing heat dissipation and preventing overheating, while maintaining structural advantages and allowing for repeated use without generating foreign debris or requiring new TIM application.

Implementation Method 1

a first conduction cooling path is formed from the circuit card assembly to the enclosure through the TIM

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

thermal interface materials (TIMs) that are compressed by wedge clamps to form multiple conduction cooling paths

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS8526184B2Devices having a thermal interface and methods of forming the same

Publication Date: 2013.09.03 ATRENNE COMPUTING SOLUTIONS LLC

AI summary

A conduction-cooled enclosure comprises a card guide having a card guide channel, at least one controlled-volume cavity in the card guide channel, and a thermal interface material (TIM) in the at least one controlled-volume cavity.