Power Semiconductor Module Recessed Surface for Substrate Protection

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Solution Overview

Problem

The existing power semiconductor modules risk damaging the insulating substrate when attaching a heat sink, due to excessive stress from the heat transfer member during the attachment process.

Innovation Solution

The power semiconductor module design includes a recessed second attachment surface for the heat transfer member, which is compressed when the heat sink is attached, preventing excessive stress on the insulating substrate by maintaining a thickness greater than the lower limit thickness of the heat transfer member, thus ensuring the substrate is not damaged.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the heat transfer member is compressed during heat sink attachment, then heat dissipation efficiency is improved, but the insulating substrate may be damaged due to excessive stress

Engineering Contradiction:

Improveheat dissipation efficiencyVSAvoidinsulating substrate integrity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The recessed second attachment surface is prepared in advance on the circuit board, creating a predetermined compression space for the heat transfer member before the heat sink attachment process begins. This preliminary structural preparation ensures that during heat sink attachment, the heat transfer member compresses into the recessed area rather than transmitting excessive stress to the insulating substrate, thus resolving the contradiction between achieving adequate compression for heat dissipation and preventing substrate damage

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The recessed second attachment surface acts as an intermediary structure between the heat transfer member and the insulating substrate. It provides a controlled compression zone that mediates the force transmission, allowing the heat transfer member to be compressed sufficiently for thermal contact while preventing the compression force from reaching the insulating substrate at damaging levels

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the heat transfer member is fully compressed, then thermal contact is improved, but the thickness reduction may cause structural failure

Engineering Contradiction:

Improvethermal contact qualityVSAvoidheat transfer member thickness

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The recessed second attachment surface is pre-formed with a depth that corresponds to the compression amount needed for optimal thermal contact. This preliminary action ensures the heat transfer member achieves the necessary compression for thermal performance while the recessed structure prevents further compression that would reduce thickness below the lower limit and cause structural failure

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the second attachment surface is flush with the first attachment surface, then manufacturing is simplified, but excessive stress is transmitted to the insulating substrate

Engineering Contradiction:

Improveattachment surface fabricationVSAvoidinsulating substrate protection

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Instead of keeping the second attachment surface flush with the first, the invention preliminarily creates a recessed second attachment surface extending in the thickness direction. This preliminary structural modification adds a small amount of manufacturing complexity but effectively prevents excessive stress transmission to the insulating substrate, resolving the contradiction between manufacturing simplicity and substrate protection

Inventive Principle:

Principle #10Preliminary action

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 design effectively prevents damage to the insulating substrate while maintaining efficient heat dissipation by ensuring the heat transfer member is compressed without reducing to its lower limit thickness, thereby improving the reliability and performance of the power semiconductor module.

Implementation Method 1

a heat transfer member (40)... to which the heat sink is attached

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11997837B2Power semiconductor module and power converter

Publication Date: 2024.05.28 MITSUBISHI ELECTRIC CORP

AI summary

The power semiconductor module includes a power semiconductor assembly and a heat transfer member. The power semiconductor assembly includes a circuit board and a case. The circuit board includes an insulating substrate. The second attachment surface to which the heat transfer member is attached is recessed from the first attachment surface to which the heat sink is attached. The maximum recessed distance of the second attachment surface from the first attachment surface is smaller than the original thickness of the heat transfer member, and is greater than the lower limit thickness of the heat transfer member.