Multi-Resin Power Module Encapsulation for Stress Relief

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Solution Overview

Problem

Conventional semiconductor power packages face challenges in achieving mechanical stability and reliable functionality, especially in high voltage applications, due to the difficulty in addressing varying local requirements for encapsulation material properties and the occurrence of mechanical and thermo-mechanical stress when using multiple resin materials.

Innovation Solution

A semiconductor power module is designed with a resin body comprising multiple resin elements of different materials, where recesses are introduced between them to act as stress relief structures, reducing mechanical and thermo-mechanical stress, and potentially filled or coated with elastic materials for improved tightness and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple resin materials are used to meet varying local requirements for encapsulation, then the functionality and protection are improved, but mechanical and thermo-mechanical stress increases

Engineering Contradiction:

Improveencapsulation functionalityVSAvoidmechanical and thermo-mechanical stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The resin body is divided into multiple resin elements (first resin element and second resin element) with different materials, each optimized for specific local requirements. The segmentation is further enhanced by introducing recesses that separate these elements, allowing each material to perform its specialized function without causing stress to the entire structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resin materials are assigned to different regions of the encapsulation based on local requirements. The first resin element and second resin element have distinct material properties tailored to their specific functional areas, enabling optimized performance in each zone while maintaining overall reliability.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a single mold compound is used for encapsulation, then manufacturing is simplified, but it cannot fulfill contradictory requirements for different regions

Engineering Contradiction:

Improveencapsulation processVSAvoidlocal material requirements

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

Instead of using a single mold compound for the entire encapsulation, the resin body is segmented into multiple elements that can be manufactured separately and then assembled. This approach maintains manufacturing simplicity while enabling each segment to be optimized for its specific functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The encapsulation uses composite construction with multiple resin materials having different properties. Each resin element is made from materials selected to meet the specific requirements of its region, creating a versatile encapsulation structure that adapts to varying local demands.

Inventive Principle:

Principle #40Composite materials

3Area of stationary object

If resin elements are placed adjacent to each other, then encapsulation coverage is improved, but stress concentration at interfaces occurs

Engineering Contradiction:

Improveencapsulation coverageVSAvoidinterface stress resistance

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

Recesses are introduced as intermediary structures between the first resin element and second resin element. These recesses act as stress relief features that separate the interface areas of adjacent resin elements, preventing stress concentration while maintaining comprehensive encapsulation coverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The recesses are designed in advance to provide stress relief at the interfaces between resin elements. By anticipating potential stress concentration at junctions, the structure incorporates these separating recesses beforehand to cushion and distribute stresses, preventing interface failure.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 enables a mechanically stable and reliable semiconductor power module with enhanced lifetime, improved thermal cycling performance, and reduced manufacturing issues, suitable for high voltage applications and harsh environments.

Implementation Method 1

The specifically introduced one or more recesses form stress relief structures between several parts of different resin materials of a resin sealed semiconductor power package

Methodology Applied

Scientific EffectStress relief: Stress Relaxation

Data Source

PatentUS20240186199A1Semiconductor power module and method for manufacturing a semiconductor power module

Publication Date: 2024.06.06 HITACHI ENERGY LTD

AI summary

A semiconductor power module for a semiconductor device comprises a leadframe or substrate and a resin body that is coupled to the leadframe or substrate. The resin body includes at least a first resin element and a second resin element, wherein a resin material of the first resin element is different from a resin material of the second resin element. The resin elements are configured such that they are separated in part at least with respect to surface areas facing each other by means of a recess.