Power Semiconductor Device with Sintered Metal Layer

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Solution Overview

Problem

Power semiconductor modules, particularly those used in vehicles and requiring wide temperature ranges, face inadequate heat dissipation and adhesion issues due to limitations in existing heat management techniques, such as thick Ni-plated and Au-plated layers causing stress and reduced productivity, and insufficient heat conductivity of Ni, leading to reduced short-circuit withstanding capacity.

Innovation Solution

A power semiconductor device configuration featuring a surface electrode with a first non-sintered compact metal layer and a second sintered compact metal layer covering the surface electrode, providing enhanced heat conductivity and adhesion through a sintered metal layer with high thermal capacity and low stress, improving heat dissipation and short-circuit withstanding capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If thick Ni-plated and Au-plated layers are used to increase thermal capacity, then heat dissipation performance is improved, but stress increases causing warpage and substrate fracture

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidsubstrate fracture

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention changes the material parameter from conventional Ni/Au plating to Cu-based sintered compact material, which has superior thermal conductivity (3.0 W/cmK or higher) and lower stress characteristics, resolving the contradiction between heat dissipation performance and substrate reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite structure consisting of a Cu-based sintered compact material combined with a ceramic substrate, creating a material system that achieves both high thermal capacity and low stress, preventing warpage and substrate fracture while maintaining excellent heat dissipation

Inventive Principle:

Principle #40Composite materials

2Temperature

If Ni-plated layers are used for heat dissipation, then thermal capacity is increased, but heat conductivity is insufficient due to Ni's lower heat conductivity

Engineering Contradiction:

Improvethermal capacityVSAvoidheat conductivity

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The invention changes the material composition from Ni-based to Cu-based sintered compact, exploiting copper's superior thermal conductivity properties to simultaneously achieve high thermal capacity and excellent heat dissipation performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If electroless plating is used for film formation, then adhesion is improved, but film-formation rate is low reducing productivity

Engineering Contradiction:

ImproveadhesionVSAvoidfilm-formation rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention replaces the electrochemical deposition process (electroless plating) with a sintering process that forms the metal layer through particle bonding and densification, achieving both strong adhesion and rapid formation suitable for mass production

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of energy

If thin substrate is used to reduce IGBT losses, then energy efficiency is improved, but heat capacity of substrate is reduced lowering short-circuit withstanding capacity

Engineering Contradiction:

ImproveIGBT lossesVSAvoidshort-circuit withstanding capacity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The invention creates a composite heat management system where a Cu-based sintered compact layer is applied on the thin substrate, providing additional thermal capacity and heat dissipation pathways that protect the thin substrate from thermal overload during short-circuit conditions

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

The configuration significantly enhances heat dissipation performance and adhesion, increasing the short-circuit withstanding capacity and reliability of power semiconductor devices, even under extreme temperature conditions.

Implementation Method 1

having higher heat conductivity than the first metal layer

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

heat generated in a semiconductor substrate is dissipated from its back surface through a lead frame

Methodology Applied

Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentUS10559659B2Power semiconductor device

Publication Date: 2020.02.11 MITSUBISHI ELECTRIC CORP

AI summary

A power semiconductor device includes an emitter electrode disposed on a semiconductor substrate and through which a main current flows, a conductive layer that is disposed on the emitter electrode and is not a sintered compact, and a sintered metal layer that is disposed on the conductive layer and is a sintered compact. The sintered metal layer has a size to cover all the emitter electrode in plan view, and has higher heat conductivity than the conductive layer. The power semiconductor device can improve heat dissipation performance and adhesion.