Power Semiconductor Module Encapsulation for Heat-Induced Brittleness
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Solution Overview
Problem
Power semiconductor module arrangements face issues with thermal and mechanical stability due to heat generation, leading to brittleness and potential failure of the encapsulant.
Innovation Solution
A method involving the use of a multi-layer encapsulant structure, where a thermostable layer with high density is placed between a substrate and a mechanically stable layer, both of which are cured simultaneously to form a solid and adherent structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer encapsulant is used to protect components, then mechanical protection is provided, but the encapsulant becomes brittle due to heat generation over time
Solution Approach 1:
The encapsulant is divided into multiple layers with different materials: a first encapsulant layer (e.g., ceramic-filled polymer) providing mechanical strength and protection, and a second encapsulant layer (e.g., silicone rubber) providing thermal stability and flexibility. This segmentation allows each layer to perform its specialized function, preventing the entire encapsulant from becoming brittle while maintaining mechanical protection.
Solution Approach 2:
The invention uses composite material structures where different encapsulant materials are combined in layers. The first layer may contain ceramic fillers for mechanical strength, while the second layer uses thermally stable polymers for heat resistance. This composite approach creates an encapsulant system that simultaneously achieves both mechanical protection and thermal stability without brittleness.
2Power
If high current density is regulated within the housing, then power control capability is improved, but heat generation increases leading to encapsulant degradation
Solution Approach 1:
The encapsulant is segmented into thermally conductive layers that channel heat away from high-current areas. The first encapsulant layer with ceramic fillers provides thermal pathways, while the second layer dissipates heat more uniformly, preventing localized overheating that would degrade the encapsulant material.
Solution Approach 2:
The invention changes the thermal parameters of the encapsulant by selecting materials with different thermal conductivities for each layer. The ceramic-filled first layer has high thermal conductivity for heat dissipation, while the silicone rubber second layer provides thermal stability. This parameter optimization allows high current density operation without encapsulant degradation.
3Productivity
If frequent switching operations are performed, then functional performance is improved, but heat generation from switching increases causing encapsulant failure
Solution Approach 1:
The dual-layer encapsulant uses composite materials where the first layer (ceramic-filled) handles high-frequency switching heat through its thermal conductivity, while the second layer (silicone rubber) provides thermal stability and flexibility. This composite structure enables frequent switching operations without the encapsulant failing from accumulated heat damage.
4Temperature
If a thermostable layer is added next to the substrate, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the thermostable layer function with the protective encapsulant function into a single integrated multi-layer structure. The first and second encapsulant layers together provide both thermal management and mechanical protection, eliminating the need for separate thermostable and protective layers. This merging reduces overall device complexity while achieving thermal stability.
Solution Approach 2:
Each encapsulant layer is designed to perform multiple functions: the first layer provides mechanical strength, thermal conduction, and partial protection, while the second layer provides thermal stability, flexibility, and additional protection. This multi-functionality reduces the need for separate specialized components, simplifying the overall device structure despite the layered approach.
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 provides enhanced thermal and mechanical stability, preventing brittleness and extending the lifetime of the power semiconductor module arrangement while maintaining protection from environmental conditions and mechanical damage.
Implementation Method 1
performing a curing step, thereby simultaneously curing the first material and the second material and forming a solid first layer and a solid second layer
Implementation Method 2
filling a second material being different from the first material and having a second density in the housing, wherein the first density is higher than the second density, thereby forming a liquid or gel-like second pre-layer, wherein the first pre-layer, due to its higher density, forms between the second pre-layer and the substrate
Data Source
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AI summary
A method comprises filling a first material having a first density in a housing, thereby forming a liquid or gel-like first pre-layer, wherein the housing comprises sidewalls, and a substrate with at least one semiconductor body arranged thereon is arranged in or forms a ground surface of the housing, and wherein the first pre-layer partly fills the housing and completely covers the substrate and the at least one semiconductor body arranged thereon, filling a second material being different from the first material and having a second density in the housing, wherein the first density is higher than the second density, thereby forming a liquid or gel-like second pre-layer, wherein the first pre-layer, due to its higher density, forms between the second pre-layer and the substrate, and performing a curing step, thereby simultaneously curing the first material and the second material and forming a solid first layer and a solid second layer, wherein the second layer permanently adheres to the first layer.