Semiconductor Substrate Pre-bending for Uniform Connection Layer

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Solution Overview

Problem

The existing methods for mounting semiconductor substrates in power semiconductor modules result in unpredictable deformation and connection layer thickness due to mismatched deflections between substrates and base plates, leading to unreliable thermal conduction and module performance.

Innovation Solution

A method involving the use of first and second bending tools with curved surfaces to pre-bend semiconductor substrates, ensuring a homogeneous connection layer thickness by matching the substrate's deflection to the base plate's, thereby reducing the need for excessive force during mounting and enhancing reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If semiconductor devices are pressed onto the first metallization layer with certain force under high temperatures, then the semiconductor devices are mounted to the substrate, but the substrate deforms with convex deflection in the direction of the first metallization layer

Engineering Contradiction:
Improvemounting processVSAvoidsubstrate deflection
Core Design Contradiction:
Ease of manufactureVSShape

Solution Approach 1:

The substrate is pre-bent to have a concave deflection before mounting the semiconductor devices. This preliminary action counteracts the convex deflection that occurs during the mounting process, ensuring that the substrate returns to a flat state after mounting, thereby resolving the shape deformation issue while maintaining ease of manufacture

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A force is applied in advance to the substrate to create a concave deflection that opposes the convex deflection caused by mounting pressure. This preliminary anti-action ensures that when mounting force is applied, the substrate deforms minimally and returns to flat, solving the contradiction between mounting ease and shape maintenance

Inventive Principle:
Principle #9Preliminary anti-action

2Ease of manufacture

If a connection layer is arranged between the base plate and substrate to fill the space, then the components are joined, but the connection layer has non-uniform thickness due to opposite deflections, leading to unpredictable thermal conduction

Engineering Contradiction:
Improveassembly processVSAvoidconnection layer thickness uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The substrate is pre-bent to a concave shape before assembly, which compensates for the convex deflection that would occur during mounting. This preliminary action ensures that when the substrate is mounted to the base plate, the connection layer maintains uniform thickness throughout, eliminating the precision issue while keeping the assembly process simple

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The deflection parameter of the substrate is changed from flat to concave before mounting. This parameter change ensures that the substrate's deflection profile matches the base plate's convex deflection, resulting in a uniformly thick connection layer and predictable thermal conduction properties

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the grade of deformation of substrate and base plate varies between different components, then manufacturing flexibility is maintained, but the connection layer thickness becomes unpredictable, limiting reliability

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidthermal conduction reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

Each substrate is pre-bent to a specific concave deflection that is tailored to compensate for the specific convex deflection of its corresponding base plate. This preliminary action ensures that despite variations in deformation grades between different components, each assembly achieves uniform connection layer thickness, thereby maintaining both manufacturing flexibility and thermal conduction reliability

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 approach ensures a consistent and reliable connection layer thickness, improving thermal conduction and overall module reliability by adjusting the substrate's deflection to match the base plate's, reducing the risk of damage during mounting and enhancing power semiconductor module performance.

Implementation Method 1

a first pressure is applied to the semiconductor substrate and to the at least one semiconductor body arranged thereon, thereby pressing the at least one semiconductor body onto the semiconductor substrate and the semiconductor substrate onto the first curved surface, thereby sintering the at least one semiconductor body to the first metallization layer of the semiconductor substrate and pre-bending the semiconductor substrate with the at least one semiconductor body mounted thereon

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

sintering the at least one semiconductor body to the first metallization layer of the semiconductor substrate

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3422394B1Method for processing a semiconductor substrate
Publication Date: 2021.09.01 INFINEON TECHNOLOGIES AG
  • EP3422394B1 patent drawingFigure 1~2B
  • EP3422394B1 patent drawingFigure 3~5A
  • EP3422394B1 patent drawingFigure 5B~5D

AI summary

A method comprises placing a semiconductor substrate on a first curved surface of a first bending tool, using a second bending tool with a second surface to apply pressure to the semiconductor substrate, thereby pressing the semiconductor substrate onto the first curved surface and bending the semiconductor substrate, and removing the bended semiconductor substrate from the first bending tool.