Power Semiconductor Module Periphery for Uniform Chip Current

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Solution Overview

Problem

In power semiconductor modules, uneven current distribution among chips leads to temperature disparities, potentially causing module failure and reducing longevity due to concentrated current at the corners during switching operations.

Innovation Solution

The use of insulating ferromagnets surrounding the periphery of the module main body redirects magnetic field lines away from chip corners, ensuring uniform current distribution and preventing magnetic saturation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If power semiconductor chips are arranged in a pressure welding type module with large number of chips, then the module can handle high current, but the current concentrates on corner chips causing uneven current distribution

Engineering Contradiction:

Improvecurrent handling capacityVSAvoidcurrent distribution uniformity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

An insulating ferromagnetic member is introduced as an intermediary element between the corner chips and the external environment. This mediator redirects magnetic field lines away from the corner chips, preventing magnetic saturation and the resulting current concentration, thereby achieving uniform current distribution across all chips while maintaining high current handling capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic properties of the module periphery are changed by introducing an insulating ferromagnetic member with specific magnetic permeability. This parameter change in the magnetic field distribution prevents magnetic saturation at corner locations, thereby eliminating the cause of uneven current distribution and enabling reliable high-power operation

Inventive Principle:

Principle #35Parameter changes

2Power

If current concentrates on corner chips during switching operation, then high power can be achieved, but uneven temperature distribution occurs among chips

Engineering Contradiction:

Improvepower outputVSAvoidtemperature distribution uniformity

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The insulating ferromagnetic member acts as a mediator that redirects magnetic field lines before they can cause concentration effects at corner chips. By controlling the magnetic field distribution, it prevents the chain reaction of uneven current flow and uneven heat generation, ensuring uniform temperature distribution while maintaining high power output

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If peripheral structures are added to redirect magnetic field lines, then current distribution uniformity is improved, but magnetic saturation may occur in the peripheral structures

Engineering Contradiction:

Improvecurrent distribution uniformityVSAvoidmagnetic saturation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A composite structure is employed combining insulating ferromagnetic material with specific magnetic properties. This composite material redirects magnetic field lines effectively to prevent corner chip saturation while its distributed geometry and insulating properties prevent saturation within the peripheral structure itself, achieving current uniformity without self-saturation

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The peripheral structure is segmented into discrete insulating ferromagnetic members positioned at specific locations rather than a continuous ring. This segmentation distributes the magnetic flux density across multiple separate elements, preventing magnetic saturation in any single element while collectively achieving uniform current distribution across all chips

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

This configuration enhances current uniformity, reduces local heat generation, and extends the module's reliability and lifespan by distributing current evenly across the semiconductor chips.

Implementation Method 1

the magnetic field line of the magnetic field generated by the transport current shifts from the outer periphery of the pressure welding type power semiconductor module into the peripheral structure by the peripheral structure surrounding the part of the periphery of the module main body

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

peripheral structures being insulating ferromagnets surrounding parts of a periphery of the module main body

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS11824048B2Power semiconductor module and composite module having peripheral structures surrounding parts of the module main body

Publication Date: 2023.11.21 MITSUBISHI ELECTRIC CORP

AI summary

An uneven current distribution among a plurality of provided power semiconductor chips is to be suppressed. A power semiconductor module includes a module main body, a plurality of power semiconductor chips arranged on an upper surface of the module main body, and peripheral structures being insulating ferromagnets surrounding parts of a periphery of the module main body in a plan view, in which the plurality of power semiconductor chips are arranged in a vertical direction and a horizontal direction in a plan view, and at least one of the plurality of power semiconductor chips is arranged so as to be surrounded by other power semiconductor chips.