Embedded Power Electronics Assemblies With Graphite Substrates

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Solution Overview

Problem

Conventional power electronics assemblies face challenges in achieving low overall thermal resistance while maintaining a compact package size, particularly due to the large cooling requirements and differing expansion rates of various layers, which can lead to increased footprint and thermal resistance.

Innovation Solution

The power electronics assembly incorporates a circuit board assembly with a laminate panel that includes a power electronics device assembly with a substrate having a graphite layer and a metal layer, and a cold plate for enhanced heat dissipation, along with vias for thermal and electrical coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional power electronics assemblies include multiple layers formed from different materials to reduce stresses and alleviate bowing, then reliability is improved, but device complexity and total footprint increase

Engineering Contradiction:

Improvestress reductionVSAvoidnumber of layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The substrate uses a composite structure with a first layer (e.g., ceramic) and a second layer (e.g., metal) having different coefficients of thermal expansion. This composite material approach reduces accumulating stresses and alleviates bowing while maintaining a compact design with fewer overall layers compared to conventional multi-layer assemblies.

Inventive Principle:

Principle #40Composite materials

2Temperature

If power electronics devices have large cooling requirements to manage heat generation, then temperature control is improved, but device complexity and footprint increase

Engineering Contradiction:

Improveheat dissipationVSAvoidcooling structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The substrate integrates both mechanical support and thermal management functions into a single component. The first and second layers of the substrate work together to provide structural support while simultaneously managing heat dissipation, eliminating the need for separate cooling structures and reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The substrate serves multiple functions: it provides mechanical support for the power electronics device, manages thermal dissipation through its layered structure with different thermal properties, and reduces stresses from thermal expansion. This multi-functional design consolidates what would traditionally require separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the same number of layers are provided on each side of the power electronics device to reduce accumulating stresses, then reliability is improved, but total footprint increases

Engineering Contradiction:

Improvestress balanceVSAvoidtotal footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The asymmetric composite substrate structure with a first layer and a second layer of different materials provides stress balance and reduces bowing without requiring equal layers on both sides. The different coefficients of thermal expansion in the layered composite structure inherently manage thermal stresses while maintaining a compact footprint.

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 effectively reduces thermal resistance and improves cooling performance by directing heat flux from the power electronics devices to the cold plate through the graphite layer, while maintaining a compact design and reducing the total number of layers.

Implementation Method 1

The substrate includes: a graphite layer; and a metal layer encasing the graphite layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Power electronics devices have large cooling requirements due to the heat generated

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS12284792B2Power electronics assemblies having power electronics devices embedded within a flip chip

Publication Date: 2025.04.22 TOYOTA JIDOSHA KK

AI summary

A power electronics assembly including a circuit board assembly including a plurality of electrically conductive logic layers, a plurality of electrically conductive power layers, and a laminate panel provided between the plurality of electrically conductive logic layers and the plurality of electrically conductive logic layers. The laminate panel includes a power electronics device assembly including a substrate and a power electronics device. The substrate includes a graphite layer and a metal layer encasing the graphite layer. A recess is formed in an outer surface of the metal layer. The power electronics device is bonded within the recess of the outer surface of the substrate. Each electrically conductive logic layer is provided at a first surface of the laminate panel, and each electrically conductive power layer is provided at a second surface of the laminate panel opposite the first surface of the laminate panel.