Heat Dissipation Assembly With Compliant Layer For Thermal Stress
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Solution Overview
Problem
Heat dissipating assemblies for electronic circuits face challenges due to varying coefficients of thermal expansion (CTE) among materials, leading to stress buildup and potential fractures, which can cause overheating.
Innovation Solution
A layered stack with a structurally isolated material having a unique CTE, positioned between layers with matched CTEs, to absorb thermal stresses and strains, ensuring minimal stress buildup and efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple layers of materials with high thermal conductivity are used to dissipate heat quickly, then heat dissipation efficiency is improved, but thermal stress and potential fractures increase due to varying coefficients of thermal expansion
Solution Approach 1:
A compliant layer is introduced as an intermediary between layers with matched CTEs and the circuit. This compliant layer acts as a stress-absorbing mediator that deforms under thermal expansion differences, protecting the brittle circuit from thermal stress while maintaining thermal conduction path. The compliant layer has lower thermal conductivity than the high-conductivity layers but provides necessary stress relief.
Solution Approach 2:
The heat dissipation assembly uses a composite structure with multiple material layers including brittle materials (ceramics, glass, semiconductors) with matched CTEs, compliant materials (polymers, elastomers, metals) for stress absorption, and conductive materials for heat transfer. This composite approach allows each layer to perform its specific function while working together to solve both heat dissipation and stress resistance requirements.
2Reliability
If layers with matched CTEs are used to reduce thermal stress, then reliability is improved, but heat dissipation efficiency may be reduced due to additional material layers
Solution Approach 1:
Different regions of the heat dissipation assembly have different material properties optimized for their specific functions. The compliant layer is positioned locally where stress absorption is needed, while high-conductivity materials are placed in the thermal conduction path. The circuit interface layer uses matched CTE materials locally at the bonding interface to reduce stress, while other layers focus on heat dissipation.
3Reliability
If a compliant layer with low thermal conductivity is used to absorb thermal stress, then thermal stress resistance is improved, but heat dissipation efficiency deteriorates
Solution Approach 1:
The heat dissipation assembly is segmented into distinct functional zones: a thermal conduction path with high-conductivity materials for efficient heat removal, and a stress management zone with compliant layers for thermal stress absorption. This segmentation allows each segment to optimize its primary function while the overall assembly achieves both heat dissipation and stress resistance through the coordinated work of its segments.
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 effectively minimizes thermal stress-induced failures and enhances heat dissipation by allowing the structurally isolated material to deform, maintaining a stable and efficient cooling path for electronic circuits.
Implementation Method 1
The coefficients of thermal expansion (CTE), the amount that the materials expand for an amount of heat applied to them, of these materials vary widely. The different expansion rates may result in the generation of high stresses
Implementation Method 2
the structurally isolated material, which is a relatively soft material (i.e., a material having a low modulus of elasticity), dissipates thermally induced stresses and strains by deforming within the layered stack
Implementation Method 3
Heat dissipating assemblies used with electrical circuits often include multiple layers of materials having high thermal conductivity for quickly removing heat away from the circuit
Data Source
AI summary
A heat dissipating assembly including a layered stack of materials with a highly thermally conductive path for cooling a circuit, the stack including a structurally isolated material having a high coefficient of thermal expansion connected between materials having low coefficients of thermal expansion.