Power Semiconductor Module Housing with Elastic Plastic Casting
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Solution Overview
Problem
Conventional power semiconductor modules with epoxy resin housings face challenges such as high manufacturing complexity and cost, brittleness, and susceptibility to cracks under thermal and mechanical stress, leading to potential short-circuits and failure in harsh environments.
Innovation Solution
A power semiconductor module with a housing made from a hardenable plastic casting compound having a hardness between 30 and 95 ShoreA, providing high elastic deformability and stability, allowing for easy manufacturing and resistance to shocks and impacts, using a thermoplastic hot-melt adhesive with a low coefficient of linear expansion and flexural modulus to prevent cracking and ensure insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin with high filler proportion is used for the housing, then the housing achieves high hardness and good insulating effect, but the housing becomes very brittle and susceptible to cracks under thermal and mechanical stress
Solution Approach 1:
The patent changes the material parameters by selecting a thermoplastic polymer instead of epoxy resin, achieving a hardness between 30 and 95 Shore A that provides both mechanical strength and elastic deformability. This parameter change resolves the contradiction by enabling the housing to deform elastically under stress rather than cracking, while still maintaining adequate hardness for structural integrity and insulation.
Solution Approach 2:
The patent employs composite material strategies by incorporating reinforcement elements such as glass fibers or mineral fillers into the thermoplastic polymer matrix. This creates a composite structure that combines the toughness and elastic deformability of the polymer with the strength and stiffness of the reinforcement, achieving both high hardness and crack resistance simultaneously.
2Reliability
If epoxy resin is used to form the housing, then the housing provides good insulating effect, but the manufacturing process requires high temperature (230°C) and high pressure (30-150 bar) making it complicated and expensive
Solution Approach 1:
The patent changes the processing parameters by using a thermoplastic polymer that can be molded at lower temperatures and pressures compared to epoxy resin. The thermoplastic material softens at lower temperatures, enabling injection molding or other forming processes to be conducted under milder conditions, thereby simplifying manufacturing and reducing costs while still achieving the required insulating properties.
Solution Approach 2:
The patent replaces the chemical curing process of epoxy resin with the physical melting and solidification process of thermoplastic polymers. This substitution eliminates the need for high-temperature curing and complex pressure control systems, allowing for simpler and more cost-effective manufacturing processes while maintaining the insulating effect.
3Strength
If epoxy resin housing is used, then the housing provides structural support, but the high coefficient of linear expansion (10-25 ppm/°K) and high flexural modulus (>5 GPa) cause undesirable tensions and cracks during heating
Solution Approach 1:
The patent changes the material parameters by selecting a thermoplastic polymer with a lower coefficient of linear expansion and lower flexural modulus compared to epoxy resin. This parameter change enables the housing to expand and contract more readily during thermal cycling, reducing thermal stresses and preventing cracks while still providing adequate structural support for the power semiconductor components.
Solution Approach 2:
The patent utilizes thermal expansion principles by choosing a thermoplastic material whose coefficient of linear expansion is better matched to the enclosed power semiconductor components. This matching reduces differential thermal expansion stresses during heating and cooling cycles, preventing cracks and maintaining structural integrity and thermal stability.
4Reliability
If epoxy resin housing is used, then the housing provides insulation, but the brittleness results in increased susceptibility to shocks and impacts
Solution Approach 1:
The patent changes the material parameters by using a thermoplastic polymer with higher toughness and lower brittleness compared to epoxy resin. The thermoplastic material can absorb impact energy through elastic deformation and plastic flow, significantly reducing susceptibility to shocks and impacts while maintaining the insulating effect required for electrical isolation.
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 module achieves reduced risk of cracking, enhanced durability, and reliable insulation, enabling operation in harsh environments with high acceleration forces, and simplified manufacturing processes.
Implementation Method 1
a hardenable plastic casting compound... which has a hardness between 30 and 95 ShoreA... providing a particularly high elastic deformability
Implementation Method 2
using a thermoplastic hot-melt adhesive with a low coefficient of linear expansion and flexural modulus to prevent cracking and ensure insulation
Implementation Method 3
providing a particularly high elastic deformability relative to a high coefficient of thermal expansion in the hardened state. Consequently, hardly any undesirable tensions occur when the housing is heated
Implementation Method 4
high coefficient of thermal expansion in the hardened state... coefficient of linear expansion (CTE(α1)) between 10 and 25 ppm/° K
Data Source
AI summary
A power semiconductor module is disclosed with a housing that includes a hardenable plastic casting compound and a base plate, wherein electric power semiconductor components are arranged on a section of the surface of the base plate that faces the housing via an insulating layer. At least the section of the surface of the base plate that faces the housing and contains the electric power semiconductor components is encapsulated in the housing wherein the hardenable plastic casting compound has a hardness between 30 and 95 ShoreA.