Fiber-Reinforced Power Module Encapsulation for Thermal Cycling Stress
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Solution Overview
Problem
Semiconductor power modules face mechanical stress issues due to thermal cycling and fixing to coolers, leading to voids or cracks in encapsulation, which existing technologies struggle to prevent effectively, especially in larger packages.
Innovation Solution
A semiconductor power module with a substrate layer and a molded body that includes embedded fiber and/or mesh structures for local reinforcement, using two different molding compounds to enhance mechanical stability, particularly in critical areas like thin walls and screw connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional molding compounds with high filler content (80-90% silica particles) are used to adjust thermal expansion coefficient and achieve desired dielectric behavior, then thermal expansion matching and dielectric properties are improved, but the molding compound becomes brittle and mechanical stability deteriorates
Solution Approach 1:
The patent uses a hybrid composite approach by combining silica particles (for thermal expansion control) with glass fibers (for mechanical reinforcement) in the molding compound. This creates a multi-phase composite material that simultaneously achieves thermal matching and mechanical strength, resolving the brittleness issue caused by high silica content alone.
Solution Approach 2:
The patent modifies the composition parameters of the molding compound by introducing glass fibers at specific concentrations (0.1-10 wt%) alongside silica particles. This parameter adjustment transforms the material properties, maintaining the thermal expansion coefficient match while significantly improving mechanical stability and reducing brittleness.
2Area of stationary object
If the size of molded packages is increased for large power packages (edge length 50 mm or more, up to 100 mm), then application scope and power handling capability are improved, but mechanical sensitivity to stress increases and stability deteriorates
Solution Approach 1:
For large packages, the patent employs glass fiber reinforcement in the molding compound to provide structural integrity across extended dimensions. The fibrous network distributes mechanical stresses throughout the larger volume, preventing the brittleness and cracking that would otherwise occur in oversized packages with conventional high-silica compounds.
Solution Approach 2:
The patent applies localized reinforcement strategies by concentrating glass fibers in critical stress zones of large packages, such as areas near screw connections and mounting holes. This local quality enhancement provides targeted mechanical support where needed most, maintaining stability in large packages without requiring uniform reinforcement throughout the entire structure.
3Strength
If fibers and mesh structures are embedded in the molded body for local reinforcement, then mechanical stability in critical areas is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent integrates glass fibers directly into the molding compound matrix, creating a fiber-reinforced composite that provides structural reinforcement as an inherent material property rather than a separate component. This approach simplifies the overall device structure by combining the reinforcement function within the material itself, eliminating the need for separate fiber assemblies or complex internal structures.
Solution Approach 2:
The patent merges the reinforcement function with the encapsulation function by incorporating glass fibers into the molding compound that also serves as the protective enclosure. This consolidation combines multiple functions (structural support, electrical insulation, environmental protection) into a single integrated component, reducing device complexity while maintaining mechanical stability.
4Reliability
If fibers and mesh structures are embedded in the molded body for local reinforcement, then resistance to voids and cracks during thermal cycling is improved, but manufacturing precision and process difficulty increase
Solution Approach 1:
The patent optimizes processing parameters such as molding temperature, pressure, and curing time to ensure proper fiber incorporation and distribution. By carefully controlling these parameters, the process achieves reliable fiber embedding without requiring excessive manufacturing precision, allowing standard production equipment to produce high-quality fiber-reinforced packages consistently.
Solution Approach 2:
The patent employs localized fiber reinforcement only in critical areas where thermal and mechanical stresses are highest, such as near mounting holes and screw connections. This selective approach reduces the overall manufacturing complexity compared to uniform fiber distribution, as it requires fiber placement precision only in specific zones rather than throughout the entire molded body.
Data Source
AI summary
A semiconductor power module (10) and method of manufacture thereof comprises a substrate layer (11) forming a baseplate and a molded body coupled thereto. The molded body has at least one fiber and/or mesh structure forming a local reinforcement portion embedded in the molded body. The semiconductor power module may be part of a semiconductor device having electronics coupled with the semiconductor power module (10).