Metal Base Substrate Insulating Resin Sheet Pinhole Prevention

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Solution Overview

Problem

Conventional metal base substrates for semiconductor devices face issues with decreased withstand voltage and complex manufacturing processes, particularly due to the use of liquid epoxy resin which fails to maintain thickness and is prone to pinholes, leading to insulation failures.

Innovation Solution

A metal base substrate comprising a copper substrate with a first metal layer, an insulating resin sheet bonded onto the metal layer, and a circuit pattern formed on the resin sheet, which improves adhesion and prevents pinhole formation, thus enhancing withstand voltage and simplifying manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If liquid epoxy resin is applied on the copper plate to form the insulating layer, then the insulating layer fails to secure a thickness thereof and fails to maintain a withstand voltage, moreover a pinhole is formed in the insulating layer

Engineering Contradiction:

Improveinsulating layer thickness uniformityVSAvoidwithstand voltage

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent replaces liquid epoxy resin with a flexible insulating resin sheet having a thickness of 5 µm to 200 µm. This sheet can be directly bonded to the copper plate surface, ensuring uniform thickness without pinhole formation, thereby maintaining both manufacturing precision and withstand voltage reliability.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent uses a pre-formed insulating resin sheet as a disposable bonding material that is bonded to the copper plate and then removed after transferring the insulating resin layer to the aluminum layer. This approach eliminates the need for complex liquid resin application processes and ensures consistent thickness and quality.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Strength

If a copper plate is used as a metal substrate with aluminum rolled on one side to form a cladding base plate, then adhesion properties are improved, but the manufacturing process becomes complicated

Engineering Contradiction:

Improveadhesion strengthVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent performs preliminary roughening of the copper plate surface before bonding the insulating resin sheet. This preliminary surface preparation improves adhesion strength without requiring complex multi-step manufacturing processes, as the roughening is done in advance and simplifies subsequent bonding operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the surface parameter of the copper plate by roughening it to increase surface area and improve adhesion. Additionally, the insulating resin sheet thickness is optimized to 5 µm to 200 µm, providing the right balance between adhesion strength and electrical insulation without complicating the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the insulating layer is formed by applying liquid epoxy resin, then the manufacturing process becomes complicated, but the insulating layer fails to secure thickness and maintain withstand voltage

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidinsulating layer thickness control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent uses a flexible insulating resin sheet with controlled thickness of 5 µm to 200 µm that can be easily bonded to the copper plate surface. This approach simplifies manufacturing by eliminating complex liquid resin application processes while ensuring precise thickness control and uniform coverage without pinholes.

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 solution effectively suppresses decreases in withstand voltage and simplifies the manufacturing process by ensuring a stable insulating layer thickness and improved adhesion, preventing insulation failures and facilitating easier assembly of semiconductor chips.

Implementation Method 1

an insulating resin sheet that is formed by bonding a sheet made of an insulating resin onto the first metal layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS9578754B2Metal base substrate, power module, and method for manufacturing metal base substrate

Publication Date: 2017.02.21 MITSUBISHI ELECTRIC CORP

AI summary

A metal base substrate of the present invention includes a copper plate made of copper, a metal layer that is formed on the copper plate and is made of a metal different from the copper, an insulating resin sheet that is formed by bonding a sheet made of an insulating resin onto the metal layer, and a circuit pattern formed on the insulating resin sheet.