Intermetallic Alloy Bonding Layer for High Temperature Substrates

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Solution Overview

Problem

Existing methods for bonding substrates fail to effectively form a strengthened bonding layer that can withstand high operating temperatures, particularly for power semiconductor devices bonded to cooling devices.

Innovation Solution

A method involving multiple high and low melting point metal layers with precursor metal particles is used to form an intermetallic alloy bonding layer by heating the metal layers and particles, creating a particle-alloy matrix region with integrated metal particles that enhance the bonding layer's strength and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bonding methods are used to bond substrates at high temperatures, then the bonding layer can be formed, but the bonding layer lacks sufficient strength and reliability to withstand high operating temperatures and thermal stress

Engineering Contradiction:

Improvebonding layer reliabilityVSAvoidbonding layer strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The bonding layer is formed as a composite intermetallic alloy structure containing multiple metal layers (high melting point metals like Ni, Pd, Pt and low melting point metals like Cu, Ag, Au) that combine to create a material with superior strength and reliability at high temperatures compared to conventional single-material bonding layers

Inventive Principle:

Principle #40Composite materials

2Temperature

If high temperature bonding is performed to strengthen the bonding layer, then the bonding layer can withstand higher temperatures, but the bonding time increases significantly

Engineering Contradiction:

Improvebonding temperature toleranceVSAvoidbonding time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

Metal layers are pre-plated onto the substrates with controlled thicknesses and compositions before bonding, and precursor metal particles are pre-positioned in the bonding interface. This preliminary preparation enables the bonding process to proceed more efficiently at elevated temperatures without requiring excessively long bonding times

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If multiple metal layers are used to form a strengthened bonding layer, then the bonding layer can withstand thermal expansion and stress, but the manufacturing complexity increases

Engineering Contradiction:

Improvebonding layer stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The bonding layer is segmented into multiple distinct metal layers, each with specific functions: high melting point metal layers provide structural stability and stress resistance, while low melting point metal layers facilitate bonding and accommodate thermal expansion. This segmentation allows each layer to be optimized for its specific function while maintaining overall manufacturing feasibility through standardized plating processes

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 intermetallic alloy bonding layer effectively withstands stress and thermal expansion without cracking, while reducing bonding time and improving the reliability of high-temperature substrate bonding.

Implementation Method 1

heating the plurality of precursor metal particles, the first high melting point metal layer, the first low melting point metal layer, the second low melting point metal layer, and the second high melting point metal layer to a bonding temperature

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

bonding the first substrate to the second substrate by heating the plurality of precursor metal particles... to form an intermetallic alloy bonding layer

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS9620434B1High temperature bonding processes incorporating metal particles and bonded substrates formed therefrom

Publication Date: 2017.04.11 DENSO CORP

AI summary

A method of bonding a first substrate to a second substrate includes disposing a first high melting point metal layer onto a first substrate, disposing a first low melting point metal layer onto the first high melting point metal layer, disposing a second high melting point metal layer onto a second substrate, and disposing a second low melting point metal layer onto the second high melting point metal layer. The method further includes applying precursor metal particles onto the first and/or second low melting point metal layers, positioning the first and second low melting point metal layers such that the precursor metal particles contact both the first and second low melting point metal layers, and bonding the first substrate to the second substrate by heating the precursor metal particles and each metal layer to form an intermetallic alloy bonding layer between the first and second substrates.