Layered Composite for High-Temperature Power Electronics

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Solution Overview

Problem

Existing connection technologies for electronic components, particularly in power electronics, face challenges with thermal stability, mechanical reliability, and compliance with environmental regulations, especially at high temperatures and under thermal cycling, due to limitations in current solder materials and techniques.

Innovation Solution

A layered composite comprising a carrier film with a sinterable layer containing metal powder and a solder layer, which allows for the formation of stable, high-temperature-resistant joints through interdiffusion, providing excellent thermal shock resistance and compensation for different thermal expansion coefficients, using materials like silver and lead-free solders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If lead-free hard solders are used for high-temperature applications, then operating temperature range is improved, but device complexity increases and manufacturing becomes more difficult

Engineering Contradiction:
Improveoperating temperature rangeVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

A carrier film is introduced as an intermediary element between the joining partners. This carrier film enables the use of lead-free hard solders for high-temperature applications while simplifying the manufacturing process by providing a stable base for the layered composite structure, allowing the complex high-temperature soldering process to be managed through a controlled intermediate substrate

Inventive Principle:
Principle #24Intermediary (Mediator)

2Temperature

If silver-containing sintered joints are used for low-temperature joining, then manufacturing temperature is reduced, but thermal shock resistance deteriorates

Engineering Contradiction:
Improvemanufacturing temperatureVSAvoidthermal shock resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The invention employs a composite layered structure consisting of multiple functional layers including sinterable layers, solder layers, and carrier films. This composite material approach combines the low-temperature joining advantage of sintered silver with the thermal shock resistance of the multi-layer composite structure, where each layer contributes specific properties that collectively enhance overall reliability under thermal cycling conditions

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If soft solders are used for connecting electronic components, then ease of manufacture is improved, but temperature resistance deteriorates

Engineering Contradiction:
Improvemanufacturing easeVSAvoidtemperature resistance
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The connection structure is segmented into multiple functional layers with distinct roles: sinterable layers for low-temperature bonding, solder layers for electrical connection, and carrier films for mechanical support. This segmentation allows each layer to be optimized for its specific function, combining the manufacturing ease of soft soldering with enhanced temperature resistance through the hierarchical structure

Inventive Principle:
Principle #1Segmentation

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 enables the production of temperature-change-resistant joints with extended service life and reduced thermo-mechanical stresses, facilitating efficient heat dissipation and maintaining electrical conductivity, suitable for high-temperature applications in power electronics.

Implementation Method 1

By interdiffusion and/or diffusion, a connection that is stable at high temperatures can be formed at temperatures that are already significantly lower than the melting temperature

Methodology Applied
Scientific EffectInterdiffusion: Diffusion

Implementation Method 2

By interdiffusion and/or diffusion, a connection that is stable at high temperatures can be formed at temperatures that are already significantly lower than the melting temperature

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 3

Under the sintering conditions, in particular under the influence of temperature and pressure, the stabilizing components are burned out and/or the silver compounds are broken up

Methodology Applied
Scientific EffectDecomposition: Decomposition (biological)

Implementation Method 4

provide a very good compensation for the different thermal expansion coefficients

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2761056B1Layered composite of a substrate film and of a layer assembly comprising a sinterable layer made of at least one metal powder and a solder layer
Publication Date: 2019.02.27 ROBERT BOSCH GMBH
  • EP2761056B1 patent drawingFigure 1~2

AI summary

The invention relates to a layered composite (10), in particular for connecting electronic components as joining partners, comprising at least one substrate film (11) and a layer assembly (12) applied to the substrate film. The layer assembly comprises at least one sinterable layer (13), which is applied to the substrate film (11) and which contains at least one metal powder, and a solder layer (14) applied to the sinterable layer (13). The invention further relates to a method for forming a layered composite, to a circuit assembly containing a layered composite (10) according to the invention, and to the use of a layered composite (10) in a joining method for electronic components.