Power Converter Package Structure for Moisture-Resistant Insulation

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Solution Overview

Problem

Conventional semiconductor devices face moisture infiltration through the heat transfer layer, leading to corrosion and reduced reliability due to exposure of the metal components at the terminal portion, which compromises the electrical insulation and heat radiation capabilities.

Innovation Solution

The semiconductor device incorporates a metal base substrate with a first insulating layer, a support conductor, and a second insulating layer, with a case provided outside the second insulating layer to prevent moisture ingress, and includes a sealing member to protect the semiconductor element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the case is provided on the heat transfer layer of the metal base substrate, then the semiconductor device structure is simplified and manufacturing is easier, but moisture infiltrates through the exposed heat transfer layer causing corrosion and reducing reliability

Engineering Contradiction:

Improveease of manufactureVSAvoidmoisture resistance reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The heat transfer layer is divided into two distinct layers: a first heat transfer layer in contact with the lead frame for thermal management, and a second heat transfer layer covering the exposed portions of the first heat transfer layer and lead frame to provide environmental protection. This segmentation allows each layer to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structure where the second heat transfer layer is applied over the first heat transfer layer, creating a composite system that combines the thermal conductivity benefits of the first layer with the moisture barrier properties of the second layer, thereby achieving both heat dissipation and corrosion protection.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If the heat transfer layer is exposed to outside air, then the structure remains simple, but moisture infiltration causes corrosion of metal components and breakdown of the semiconductor device

Engineering Contradiction:

Improvedevice complexityVSAvoidmoisture infiltration

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The second heat transfer layer acts as a protective film or shell that covers the exposed surfaces of the first heat transfer layer and lead frame. This thin film structure provides effective moisture barrier protection while adding minimal structural complexity to the overall device design.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The second heat transfer layer serves as an intermediary protective layer between the external environment (moisture) and the internal metal components (lead frame and first heat transfer layer), preventing direct contact and subsequent corrosion while maintaining the simplicity of the overall structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the heat transfer layer provides electrical insulation, then electrode insulation is improved, but the exposed portion still allows moisture to reach metal components

Engineering Contradiction:

Improveelectrical insulationVSAvoidmoisture exposure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The heat transfer structure is segmented into two functional layers: the first heat transfer layer provides electrical insulation in contact with the lead frame, while the second heat transfer layer covers the exposed portions to prevent moisture infiltration. This segmentation allows simultaneous achievement of electrical insulation and moisture protection.

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 moisture resistance and reliability by preventing moisture infiltration, improving electrical insulation and heat radiation while ensuring the semiconductor device's structural integrity and reducing size.

Implementation Method 1

a second insulating layer provided on a side surface of the support conductor so as to expose a surface of the support conductor opposite to the surface in contact with the first insulating layer

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

a sealing member filled in a region surrounded by the support conductor, the second insulating layer and the case

Methodology Applied

Scientific EffectMoisture barrier: Physical Containment

Implementation Method 3

a case provided outside the second insulating layer, an external terminal attached to the case

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS12469802B2Semiconductor device and power converter

Publication Date: 2025.11.11 MITSUBISHI ELECTRIC CORP

AI summary

The present invention provides a semiconductor device and a power converter having improved moisture resistance reliability. The semiconductor device of the present invention includes: a metal base substrate which includes a first insulating layer provided on a metal base, a support conductor provided on the first insulating layer, and a second insulating layer provided on a side surface of the support conductor; a semiconductor element bonded to the support conductor; a case provided outside the second insulating layer; an external terminal attached to the case; and a sealing member filled in a region surrounded by the support conductor, the second insulating layer and the case.