Power Module Creepage Coating for Electrical Breakdown Prevention

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Solution Overview

Problem

In high voltage environments, existing power modules face challenges in maintaining sufficient creepage distance to prevent electrical breakdown between conductive parts, especially due to variations in pollution levels, distances, and material resistance to surface tracking.

Innovation Solution

A power semiconductor module with a housing featuring a coating of high resistance to surface tracking applied on the creepage distance between electrical conductors, which increases the resistance to electrical breakdown and enhances insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the spacing between conductive parts is increased to prevent electrical breakdown, then the reliability is improved, but the device complexity and space requirements worsen

Engineering Contradiction:

Improveelectrical breakdown preventionVSAvoidspacing requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies a coating with high resistance to surface tracking specifically on the creepage distance between conductive parts, rather than requiring increased spacing throughout the entire device. This local enhancement of insulating properties allows maintaining standard spacing while preventing electrical breakdown along the surface path.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a composite structure combining the base housing material with a specialized coating layer that has high resistance to surface tracking. This composite approach enhances the insulating properties of the creepage distance without requiring the entire structure to be made from specialized materials, thus avoiding increased device complexity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a coating of high resistance to surface tracking is applied on the creepage distance, then the resistance to surface tracking is improved, but the manufacturing complexity worsens

Engineering Contradiction:

Improveresistance to surface trackingVSAvoidcoating application process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent specifies that the coating should have a comparative tracking index (CTI) of at least 600, which is a parameter change that quantifies the required resistance to surface tracking. This clear parameter specification allows for standardized material selection and quality control, simplifying the manufacturing process despite the additional coating step.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively increases the resistance to surface tracking along the creepage distance, reducing the risk of electrical breakdown and ensuring reliable operation under high voltage conditions.

Implementation Method 1

at least one coating of high resistance to surface tracking; the coating being provided on a creepage distance between the electrical conductors

Methodology Applied

Scientific EffectSurface tracking resistance: Electrical Resistance

Data Source

PatentUS7763970B2Power module

Publication Date: 2010.07.27 INFINEON TECHNOLOGIES AG

AI summary

A power semiconductor module comprises a housing. The housing comprises a casing and at least one coating of high resistance to surface tracking. A plurality of electrical conductors is provided on the housing. The coating is provided on a creepage distance that is provided between the electrical conductors.