Semiconductor Sealing Structure for Crack-Resistant Moisture Blocking

Solution Overview

Problem

Conventional power semiconductor modules experience cracking and peeling due to thermal stress, leading to reduced reliability and insulation failure, as existing sealing structures fail to prevent moisture ingress through cracks.

Innovation Solution

A semiconductor device with a sealing structure comprising a thermosetting resin sealing layer and a protective silicone rubber layer, where the protective layer has a tensile strength × elongation at break value (A2) that is greater than the sealing layer's (A1) but less than 25 times A1, and includes an inorganic filler, to prevent moisture entry and ensure adhesion even when cracks occur.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hard sealing material is used to suppress peeling of the semiconductor element, then adhesion is improved, but thermal stress resistance deteriorates causing cracking

Engineering Contradiction:

Improveadhesion strengthVSAvoidthermal stress resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The sealing structure is divided into two distinct layers: a hard sealing layer (epoxy resin) that provides strong adhesion to suppress peeling, and a soft protective layer (silicone rubber) that provides thermal stress resistance. This segmentation allows each layer to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sealing structure have different material properties optimized for their specific functions. The sealing layer in contact with the semiconductor element uses hard material for strong bonding, while the outer protective layer uses soft material for stress absorption and crack prevention.

Inventive Principle:

Principle #3Local quality

2Reliability

If the sealing layer is made soft to reduce thermal stress, then thermal stress resistance is improved, but adhesion strength deteriorates causing peeling

Engineering Contradiction:

Improvethermal stress resistanceVSAvoidadhesion strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The sealing structure is divided into two distinct layers: a hard sealing layer (epoxy resin) that provides strong adhesion to suppress peeling, and a soft protective layer (silicone rubber) that provides thermal stress resistance. This segmentation allows each layer to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If a single-layer sealing structure is used to simplify manufacturing, then device complexity is reduced, but reliability deteriorates due to cracking and peeling

Engineering Contradiction:

Improvesealing structure complexityVSAvoidcrack and peel resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The sealing structure is divided into two distinct layers: a hard sealing layer (epoxy resin) that provides strong adhesion to suppress peeling, and a soft protective layer (silicone rubber) that provides thermal stress resistance. This segmentation allows each layer to perform its specialized function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sealing structure uses a composite of two different materials: epoxy resin for the sealing layer and silicone rubber for the protective layer. This composite approach combines the advantages of both materials—strong adhesion from the epoxy and thermal stress resistance from the silicone—into a single integrated sealing system.

Inventive Principle:

Principle #40Composite materials

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 prevents moisture ingress and maintains reliability by ensuring the protective layer can elongate and adhere to the sealing layer, reducing peeling and enhancing power cycle resistance.

Implementation Method 1

a protective layer coating the sealing layer and comprising a silicone rubber... the value A2 is 1600 MPa or less

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a sealing layer that seals members to be sealed comprising the laminated substrate, the semiconductor element, and the electrically conductive connecting member and includes a thermosetting resin

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Data Source

PatentUS12125756B2Semiconductor device

Publication Date: 2024.10.22 FUJI ELECTRIC CO LTD

AI summary

A semiconductor device in which even when cracks occur in a sealing material, the entry of moisture through the cracks can be prevented. A semiconductor device comprising a semiconductor element 11 mounted on a laminated substrate 12 and an electrically conductive connecting member, and a sealing material which seals the semiconductor element and the electrically conductive connecting member, wherein the sealing material includes a sealing layer 20 sealing members to be sealed including the laminated substrate 12, the semiconductor element 11, and the electrically conductive connecting member and including a thermosetting resin, and a protective layer 21 coating the sealing layer and including a silicone rubber, and wherein a value A1 of a tensile strength × elongation at break of the sealing layer 20 is less than a value A2 of a tensile strength × elongation at break of the protective layer 21, and the A2 is 1600 MPa or less.