Composite Thermal Interface Object with Orthogonal Graphite Fibers

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Solution Overview

Problem

Conformable thermal interface materials (TIMs) can adhere too strongly to heat sources and heat sinks, potentially damaging electrical components when removed, due to their inability to support the components and causing them to fall back and damage the socket.

Innovation Solution

A composite thermal interface object is created with multiple layers of TIMs, including a stiffer layer with different compliance characteristics to reduce adherence and a more compliant layer with graphite fibers aligned orthogonally to the surface, which is formed based on the topography of the components to minimize air gaps and enhance thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a conformable thermal interface material is used to improve thermal conductivity by reducing air gaps, then thermal conductivity is improved, but the material adheres too strongly to the heat source and heat sink, potentially damaging electrical components during removal

Engineering Contradiction:

Improvethermal conductivityVSAvoidadherence damage to components

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The thermal interface material is divided into multiple layers with different compliance characteristics. The first layer has higher compliance to conform to surfaces and reduce air gaps, while the second layer has lower compliance to reduce adherence strength. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between thermal conductivity and component damage prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses a composite structure combining materials with different compliance properties. The composite thermal interface material integrates a compliant first layer (e.g., silicone-based) with a less compliant second layer (e.g., polymer-based), creating a material system that simultaneously achieves high thermal conductivity through conformability and reduced adherence through the stiffer second layer.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a compliant thermal interface material is used to conform to surfaces and reduce air gaps, then thermal conductivity is improved, but the material may lift the CPU out of its socket during removal, causing damage

Engineering Contradiction:

Improvethermal contact qualityVSAvoidadherence strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Different regions of the thermal interface material have different compliance characteristics. The first layer maintains high compliance locally at the heat source interface to ensure conformability and thermal contact, while the second layer provides locally reduced compliance to limit adherence strength and prevent CPU lifting during removal.

Inventive Principle:

Principle #3Local quality

3Temperature

If the thermal interface material adheres strongly to the heat sink to improve thermal contact, then thermal conductivity is improved, but the CPU may fall back down and damage the socket upon removal

Engineering Contradiction:

Improvethermal contactVSAvoidcomponent damage from falling

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The multi-layer structure is designed in advance to prevent the harmful effect of component damage. The second layer with lower compliance acts as a cushioning element that limits the maximum adherence force, preventing the CPU from being lifted out of the socket during heat sink removal, thereby avoiding subsequent damage from the CPU falling back down.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 composite thermal interface object provides high thermal conductivity while reducing the risk of damage to electrical components during removal by minimizing adherence and optimizing contact area, thus improving thermal performance and component safety.

Implementation Method 1

a first layer including a first thermal interface material that has first compliance characteristics. The first layer includes first graphite fibers

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Thermal interface materials (TIMs) are materials that are employed to reduce thermal resistance at a thermal interface of a heat source and a heat exchanger

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11335621B2Composite thermal interface objects

Publication Date: 2022.05.17 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

In an example, a composite thermal interface object includes a first layer including a first thermal interface material that has first compliance characteristics. The first layer includes first graphite fibers, and the first graphite fibers are aligned in a direction that is substantially orthogonal to a surface of the first layer. The composite thermal interface object further includes a second layer including a second thermal interface material that has second compliance characteristics that are different from the first compliance characteristics.