Power Semiconductor Module Encapsulation for Heat-Stable Layering
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Solution Overview
Problem
Power semiconductor module arrangements face challenges with heat generation leading to encapsulant brittleness and potential failure, as existing encapsulants degrade thermally and mechanically over time.
Innovation Solution
A multi-layer encapsulant structure is introduced, comprising a thermostable first layer and a mechanically stable second layer, where the first layer is denser and forms between the second layer and the substrate, and both layers are cured simultaneously to ensure permanent adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer encapsulant is used to protect semiconductor components, then mechanical protection is provided, but the encapsulant becomes brittle and fails due to thermal degradation over time
Solution Approach 1:
The encapsulant is divided into multiple layers with different materials and functions. The first layer (thermostable layer) provides thermal stability and remains flexible at high temperatures, while the second layer provides mechanical protection. This segmentation allows each layer to specialize in one function, preventing the single-layer encapsulant from degrading and becoming brittle over time.
Solution Approach 2:
The patent uses composite material structure combining a thermostable material (such as silicone rubber) and a mechanically stable material (such as epoxy resin or polyimide). This composite structure leverages the thermal resistance of the first material and the mechanical strength of the second material, creating an encapsulant that resists both thermal degradation and mechanical damage throughout its service life.
2Temperature
If heat is dissipated from semiconductor elements through the encapsulant, then thermal management is achieved, but the encapsulant material degrades and becomes brittle
Solution Approach 1:
The encapsulant is segmented into a first thermostable layer that directly contacts the semiconductor elements and handles thermal management, and a second mechanically stable layer that protects against environmental degradation. This segmentation isolates the thermal stress to the first layer, which is designed to withstand high temperatures, while the second layer remains stable and protective throughout the device lifetime.
Solution Approach 2:
The patent changes the material parameters of the encapsulant by selecting materials with appropriate glass transition temperatures and thermal stability characteristics. The first layer uses materials like silicone rubber with high thermal stability and flexibility at operating temperatures, while the second layer uses materials with high mechanical stability. This parameter optimization prevents material degradation while maintaining effective heat dissipation.
3Reliability
If a multi-layer encapsulant structure is implemented to improve thermal and mechanical stability, then reliability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The encapsulant is segmented into two functional layers, which increases reliability by assigning specific functions to each layer. However, the patent minimizes the resulting complexity by using a simple sequential lamination process where layers are applied one after another, and by using materials that can be cured under the same conditions, thus avoiding complex manufacturing steps.
4Adaptability or versatility
If two different materials are used in the encapsulant layers, then thermal and mechanical properties are optimized, but adhesion between layers may be insufficient
Solution Approach 1:
The patent optimizes material parameters by selecting materials with compatible surface energies and chemical structures that promote adhesion. The first thermostable layer and second mechanically stable layer are chosen such that they form strong interfacial bonds. Additionally, the curing parameters are optimized to ensure complete cross-linking and strong adhesion between layers without causing material degradation.
Solution Approach 2:
The patent uses composite materials science to select material combinations that inherently provide good interlayer adhesion. The interface between the first and second layers is designed to have strong chemical or physical bonding, ensuring that the multi-layer structure acts as a unified protective system rather than separate layers that might delaminate.
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 solution provides a thermally and mechanically stable power semiconductor module arrangement, reducing the risk of encapsulant brittleness and failure, 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
AI summary
A method includes: filling a first material having a first density in a housing to form a liquid or gel-like first pre-layer, the housing having sidewalls, and a substrate with at least one semiconductor body arranged thereon is arranged in or forms a ground surface of the housing, the first pre-layer partly filling the housing and completely covering the substrate and the at least one semiconductor body; filling a second material being different from the first material and having a second density in the housing, the first density being higher than the second density, to form a liquid or gel-like second pre-layer, the first pre-layer forming between the second pre-layer and the substrate; and performing a curing step that simultaneously cures the first material and the second material and forms a solid first layer and a solid second layer, the second layer permanently adhering to the first layer.