Stacked Thermal Interface Materials for Heat Dissipation

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Solution Overview

Problem

Conventional heat dissipation structures face issues with thermal interface materials causing efficiency loss due to overflow or damage from compressive forces, leading to assembly tolerance problems and potential BGA cracks.

Innovation Solution

A heat dissipation structure utilizing a combination of a fluid first thermal interface material and a non-fluid second thermal interface material, where the first material is connected to the heat sink and the second material is connected to the circuit board, absorbing assembly tolerance and preventing excessive force on the circuit element, while the second material provides structural support and prevents overflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a thermal interface material with fluidity is used, then heat conduction efficiency is improved, but the material overflows to another surface of the circuit element and affects circuit efficiency

Engineering Contradiction:

Improveheat conduction efficiencyVSAvoidmaterial overflow

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The thermal interface material system is segmented into two distinct layers: a first thermal interface material with fluidity for heat conduction, and a second thermal interface material without fluidity as a barrier layer. This segmentation allows each layer to perform its specific function - the first layer conducts heat efficiently while the second layer prevents overflow, resolving the contradiction between heat conduction and overflow prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second thermal interface material acts as an intermediary barrier between the first thermal interface material and the circuit element. This intermediary layer prevents the fluid first material from overflowing onto the circuit element surface while still allowing heat to pass through, thus resolving the conflict between maintaining heat conduction efficiency and preventing harmful overflow.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If a thermal interface material with specific body and hardness is used, then structural support is provided, but force is generated during compression that damages the circuit element or causes BGA crack

Engineering Contradiction:

Improvestructural supportVSAvoidcompressive force damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The compression function is segmented between two materials: the second thermal interface material provides structural support and compression capability, while the first thermal interface material with fluidity absorbs compressive force through deformation. This segmentation allows the system to maintain structural integrity during assembly while preventing excessive compression force from reaching the circuit element.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first thermal interface material serves as a force-absorbing intermediary layer between the second thermal interface material and the circuit element. When compression is applied, this fluid material deforms to absorb the force, preventing the hard second material from transmitting excessive compressive force to the circuit element, thus avoiding damage and BGA cracks.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If a single thermal interface material is used, then device complexity is reduced, but assembly tolerance cannot be effectively absorbed

Engineering Contradiction:

Improvematerial structure simplicityVSAvoidassembly tolerance absorption

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system changes the physical parameters of the thermal interface materials by using two materials with different fluidity characteristics. The first material has high fluidity to flow and fill gaps, while the second material has no fluidity to maintain shape. This parameter differentiation allows the composite structure to absorb assembly tolerance effectively while maintaining reasonable complexity.

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

This configuration effectively absorbs assembly tolerance, prevents thermal interface material overflow, and reduces the risk of BGA cracks, maintaining circuit efficiency and avoiding damage from compressive forces.

Implementation Method 1

a first thermal interface material (300) connected to the heat sink (200), and having fluidity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a second thermal interface material (400) connected to the first thermal interface material (300), and having no fluidity

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS11792912B2Heat dissipation structure with stacked thermal interface materials

Publication Date: 2023.10.17 WISTRON NEWEB CORP

AI summary

A heat dissipation structure includes a heat sink, a first thermal interface material, a second thermal interface material, a circuit board and a circuit element. The first thermal interface material is connected to the heat sink and has fluidity. The second thermal interface material is connected to the first thermal interface material and has no fluidity. The circuit board is connected to the second thermal interface material and has an opening, a top board surface and a bottom board surface. The circuit element includes a convex portion and a base portion. The convex portion has a top convex surface and is disposed in the opening. The base portion is connected to the convex portion and the bottom board surface. The second thermal interface material is connected to the top board surface and the top convex surface.