Semiconductor Module Low Elastic Sheet Thermal Stress Mitigation

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Solution Overview

Problem

Conventional semiconductor modules face issues with thermal expansion of metal wiring plates causing strain and cracks in the resin sealing due to the restraint of the rising portion by the sealing resin, leading to potential electrode and resin cracks.

Innovation Solution

Incorporating a sheet-like low elastic sheet with a lower elastic modulus than the metal wiring plate and sealing resin on both the bonding and rising portions of the metal wiring plate to absorb thermal expansion stresses, thereby reducing strain on the semiconductor chip and resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the metal wiring plate is solder-bonded to the upper surface electrode and sealed by resin, then electrical connection is achieved, but thermal expansion of the metal wiring plate causes strain and cracks in the resin sealing

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidthermal expansion stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A low elastic sheet is introduced as an intermediary layer between the metal wiring plate and the sealing resin. This intermediate layer absorbs thermal expansion stresses through its low elastic modulus, preventing stress transmission to the resin and eliminating cracks while maintaining electrical connection reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The elastic modulus parameter of the sheet material is specifically changed to be lower than both the metal wiring plate and sealing resin. This parameter change enables the sheet to deform more easily under thermal stress, absorbing expansion forces and protecting the resin sealing from crack formation.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the rising portion of the metal wiring plate is restrained by the sealing resin, then structural stability is achieved, but the upper surface electrode experiences greater strain

Engineering Contradiction:

Improvestructural stabilityVSAvoidelectrode strain

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The low elastic sheet acts as a stress-absorbing intermediary between the rising portion and the upper surface electrode. When the rising portion expands thermally, the sheet deforms to accommodate this movement, preventing direct stress transmission to the electrode and reducing strain while maintaining structural stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The low elastic sheet functions as a flexible thin film that can deform under thermal stress. This flexibility allows the sheet to accommodate expansion of the rising portion without transmitting harmful strains to the electrode, while still providing structural support and stability.

Inventive Principle:

Principle #30Flexible shells and thin films

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 low elastic sheet effectively mitigates thermal stress concentrations, suppressing electrode and resin cracks, and enhancing the semiconductor module's reliability by providing a cushioning effect that reduces deformation and stress concentrations.

Implementation Method 1

When the temperature of the metal wiring plate changes, the rising portion of the metal wiring plate is prone to expand or contract in a vertical direction

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the low elastic sheet having an elastic modulus lower than the elastic modulus of the metal wiring plate

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11387210B2Semiconductor module and manufacturing method therefor

Publication Date: 2022.07.12 FUJI ELECTRIC CO LTD

AI summary

A semiconductor module is provided, including: a semiconductor chip having an upper surface electrode and a lower surface electrode opposite to the upper surface electrode; a metal wiring plate electrically connected to the upper surface electrode of the semiconductor chip; and a sheet-like low elastic sheet provided on the metal wiring plate, the low elastic sheet having elastic modulus lower than that of the metal wiring plate. A manufacturing method for a semiconductor module is provided, including: providing a semiconductor chip; solder-bonding a metal wiring plate above said semiconductor chip; and applying a sheet-like low elastic sheet having the elastic modulus lower than that of said metal wiring plate to said metal wiring plate.