Conductive Thermal Stiffener Architecture for Sealed Power Electronics

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Solution Overview

Problem

In applications where electronic devices like power dies and diodes are not exposed to airflow, convective heat transfer is not possible, necessitating the use of conductive thermal management to dissipate heat effectively.

Innovation Solution

A conductive thermal management architecture is implemented using a center stiffener made of copper, ceramic plates of silicon nitride or aluminum nitride, and copper plates bonded using the direct bonding of copper (DBC) technique, with wedge locks and spring-loaded electrical contacts to secure and facilitate heat transfer from power dies and diodes to wedge lock mounting rails, enhancing thermal conductivity and reducing thermal interface resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conductive thermal management is employed without exposure to ambient atmosphere, then heat dissipation is achieved through conduction, but thermal management effectiveness is reduced compared to convective cooling

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidthermal management effectiveness

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent combines multiple thermal management functions into a single integrated stiffener structure. The stiffener merges mechanical support, thermal conduction, and structural rigidity functions, using high thermal conductivity materials (copper, aluminum) to conduct heat away from power devices while maintaining structural integrity in sealed environments where convection is unavailable.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs composite material construction with stiffeners made from high thermal conductivity materials (copper, aluminum) bonded to PWBs using high-performance adhesives. This composite approach optimizes both thermal management and mechanical properties, enabling effective heat dissipation through conduction in sealed enclosures.

Inventive Principle:

Principle #40Composite materials

2Power

If high power density electronic devices are used, then device functionality and performance are improved, but heat generation increases requiring more sophisticated thermal management

Engineering Contradiction:

Improvepower densityVSAvoidheat generation

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The stiffener acts as an intermediary thermal management component between power devices and the external environment. It provides a dedicated thermal conduction path that mediates heat transfer from high power density devices, using high thermal conductivity materials to efficiently conduct heat away from heat-generating components while maintaining electrical isolation and mechanical support.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If sealed enclosures are used to protect electronic devices, then environmental protection is improved, but convective heat transfer is eliminated

Engineering Contradiction:

Improveenvironmental protectionVSAvoidheat dissipation capability

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent replaces convective heat transfer (fluid-based) with conductive heat transfer (solid-based) as the primary thermal management mechanism. By substituting the cooling mechanism from air convection to solid-state conduction through integrated stiffeners, the system maintains sealed environmental protection while achieving effective heat dissipation through thermal conduction paths.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 architecture effectively dissipates heat from high power density electronic devices, maintaining the junction temperature below a maximum limit and enabling the use of high power devices in deep space, underwater, and ground-based applications by leveraging high thermal conductivity materials and reduced thermal interface resistance.

Implementation Method 1

The center stiffener dissipates heat from the electronic devices, and the electronic devices include power dies

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the ceramic plates are silicon nitride or aluminum nitride and are secured to the center stiffener by a direct bonding of copper (DBC) technique

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11929297B2Conductive thermal management architecture for electronic devices

Publication Date: 2024.03.12 HAMILTON SUNDSTRAND CORP

AI summary

An electronic assembly includes a first printed wiring board (PWB) on a first side of the electronic assembly, and a first stiffener secured to the first PWB. The electronic assembly also includes a second PWB on a second side of the electronic assembly, opposite the first side, a second stiffener secured to the second PWB, and a center stiffener seated in the second stiffener and between the first stiffener and the second stiffener. The center stiffener has a first side facing the first stiffener, a second side that is opposite the first side and facing the second stiffener, a first end, and a second end, opposite the first end. Electronic devices are secured to the center stiffener. The center stiffener dissipates heat from the electronic devices, and the electronic devices include power dies.