Deformable Casing Cooling for Electronic Power Devices

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Solution Overview

Problem

Electronic devices used for power applications face limited heat transfer due to ceramic substrates, leading to high operating temperatures and reduced power density, necessitating increased spacing and power limitations.

Innovation Solution

An electronic device with electronic components mounted on a support surrounded by a deformable casing containing a thermally conductive and electrically insulating liquid, which enhances heat transfer through conduction to a parallel heat dissipation plate, utilizing thermally conductive pads and shape memory materials for improved heat exchange and thermal expansion-driven pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ceramic substrate is used to fix electronic components, then electrical connection and mechanical support are ensured, but heat transfer capability is limited causing high operating temperatures

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoidoperating temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent introduces a thermally conductive and electrically insulating liquid as an intermediary substance between the electronic components and the heat dissipation plate. This liquid mediator provides superior thermal conductivity compared to the ceramic substrate alone, while maintaining electrical insulation to preserve the reliability of electrical connections. The liquid fills the gaps and interfaces, creating efficient thermal pathways without compromising electrical isolation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite cooling system combining multiple materials with complementary properties: the ceramic substrate provides mechanical support and basic electrical isolation, the thermally conductive liquid provides enhanced heat transfer, and the deformable casing with shape memory material provides adaptive mechanical pressure. This composite structure achieves both reliable electrical connection and effective heat dissipation by leveraging the strengths of each material.

Inventive Principle:
Principle #40Composite materials

2Temperature

If components are spaced apart to promote cooling, then heat dissipation is improved, but device bulk increases

Engineering Contradiction:
Improveheat dissipation efficiencyVSAvoiddevice bulk
Core Design Contradiction:
TemperatureVSVolume of stationary object

Solution Approach 1:

The patent utilizes the thermal expansion properties of the thermally conductive liquid (a hydraulic principle) to create adaptive pressure on the heat dissipation interface. As the liquid heats up, it expands and automatically increases the contact pressure between the deformable casing and the heat dissipation plate, enhancing heat transfer efficiency without requiring additional spacing between components. This allows compact component arrangement while maintaining effective cooling.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent exploits thermal expansion of the thermally conductive liquid and the shape memory material to create a self-regulating cooling system. The liquid expands when heated, applying increasing pressure on the heat dissipation interface to maintain optimal thermal contact. Simultaneously, the shape memory material in the casing expands or changes shape in response to temperature, ensuring continuous pressure on the heat dissipation plate. This allows components to be placed closer together while still achieving effective heat dissipation through the thermally enhanced contact.

Inventive Principle:
Principle #37Thermal expansion

3Power

If power transmission is increased in components, then device functionality is enhanced, but heating increases requiring larger spacing

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidcomponent heating
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The thermally conductive liquid acts as an intermediary heat transfer medium that enables higher power transmission by providing superior thermal pathways. The liquid's high thermal conductivity creates efficient heat evacuation routes from the power components, allowing them to operate at higher power levels without excessive temperature rise. The liquid fills all interface gaps and micro-voids, ensuring complete thermal contact that solid materials alone cannot achieve.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The composite cooling system enables enhanced power transmission by combining multiple heat dissipation mechanisms: the ceramic substrate provides structural support, the thermally conductive liquid provides bulk heat transfer, and the deformable casing with shape memory material provides adaptive interface pressure. This multi-material approach creates redundant thermal pathways that can handle the heat generated by high-power operation without requiring increased component spacing, thus maintaining compact device geometry while supporting higher power levels.

Inventive Principle:
Principle #40Composite materials

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 significantly enhances cooling efficiency, reduces device size, and increases power density by facilitating more effective heat dissipation and thermal management, while also simplifying the structure and extending the lifespan of components.

Implementation Method 1

The evacuation towards the heat dissipation plate of the calories produced during the operation of the component is ensured mainly by the thermally conductive and electrically insulating liquid (such as a silicone oil), the casing and the means of heat exchange by conduction

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the thermally conductive liquid having a larger exchange surface between the component and the cold area. As a result, the cooling of the component is relatively efficient. In addition, the heating of the liquid will cause it to expand so that the liquid will exert pressure on the casing

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The shape memory material used may thus be deformed during the integration of the module and will be chosen to have a critical temperature for returning to the initial position which is consistent with the operating temperatures of the module

Methodology Applied
Scientific EffectShape memory effect: Shape Memory Alloy

Data Source

PatentEP3092879B1Electronic power device with improved cooling
Publication Date: 2021.03.03 SAFRAN ELECTRONICS & DEFENSE (FR)
  • EP3092879B1 patent drawingFigure 1
  • EP3092879B1 patent drawingFigure 2~3

AI summary

The invention relates to an electronic device comprising at least one electronic component mounted on a support and surrounded by a deformable envelope containing a thermally conductive and electrically insulating liquid, said device comprising a heat dissipation plate which is substantially parallel to the support and at a distance therefrom, and means for heat transfer by conduction between the envelope and the plate, the thermally conductive and electrically insulating liquid being selected and the envelope being arranged such that a thermal expansion of the oil generates a force pressing the envelope against the means for heat exchange by conduction.