Power Semiconductor Module Baseplate Welding and Sealing
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Solution Overview
Problem
The integration of power semiconductor modules with coolers is challenging due to the need for reliable and space-efficient connections that avoid mechanical stresses and temperature damage, particularly for sintered substrates which cannot be wire bonded before sintering, and existing solutions require O-rings and screws, leading to complexity and potential leakage issues.
Innovation Solution
A method involving intermittent welding and sealing of casing components to a baseplate using a two-step process, where specific areas are welded to create a mechanical connection while a sealing agent ensures leak-tightness, reducing heat influence and eliminating the need for O-rings and screws, using techniques like tack welding and laser welding to maintain mechanical stability and prevent fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sintering approach is used to connect substrates, then cycle reliability is improved, but wire bonding capability is lost due to strong pressure requirements
Solution Approach 1:
The connection process is segmented into two distinct stages: first, wire bonding is performed on the substrate before sintering to establish electrical connections; second, sintering is applied to the completed assembly to create the mechanical and thermal connection to the cooler. This segmentation allows both wire bonding and sintering to be performed under their respective optimal conditions without interference.
2Reliability
If O-rings and screws are used for integration, then sealing is achieved, but device complexity increases and space is consumed
Solution Approach 1:
The sealing function and mechanical fastening function are merged into a single integrated baseplate structure. The baseplate incorporates sealing elements and connection features directly into its design, eliminating the need for separate O-rings and screws. This integration reduces the number of components, simplifies the assembly process, and decreases the overall space required while maintaining sealing reliability.
3Strength
If welding is used to connect casing components, then mechanical strength is improved, but temperature damage risk increases to mold compound
Solution Approach 1:
The baseplate is designed with localized welding zones that are spatially separated from the mold compound areas. The welding is concentrated in specific regions where casing components need to be mechanically connected, while the areas containing the mold compound are protected from excessive heat exposure. This local concentration of thermal energy allows strong mechanical connections without damaging temperature-sensitive materials.
4Ease of manufacture
If transfer-molded modules are used instead of sintered modules, then wire bonding and testing are possible, but integration reliability decreases due to O-ring aging and leakage risks
Solution Approach 1:
The baseplate employs a composite structure combining materials with different properties: regions with high thermal conductivity for efficient heat transfer to the cooler, regions with appropriate mechanical properties for strong sintering connections, and sealing materials integrated into the structure to prevent leakage. This composite approach allows the baseplate to simultaneously achieve thermal performance, mechanical strength, and sealing reliability without relying on aging O-rings.
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 approach provides a reliable, efficient, and compact cooling solution for power semiconductor modules, reducing the risk of damage and leakage, and enabling the use of transfer-molded modules with improved temperature resistance and reduced production complexity.
Implementation Method 1
The first casing component is welded to the baseplate by an intermittent welding technique along a first mechanical connection path which fully surrounds the opening. A second casing component is welded to the first casing component by an intermittent welding technique along a second mechanical connection path which fully surrounds the cooling channel.
Implementation Method 2
A sealing agent is provided along a first sealing path which fully surrounds the opening in order to seal the baseplate against the first casing component. A sealing agent is provided along a second sealing path in order to seal the first casing component against the second casing component.
Implementation Method 3
A cooling channel is provided between the first casing component and the second casing component, which is adapted for receiving cooling fluid. The cooling area is adapted for being cooled by the cooling fluid.
Data Source
AI summary
One embodiment provides a method of providing a power semiconductor module with a cooler. A power semiconductor module includes a substrate having a first substrate side for carrying at least one electric circuit and having a second substrate side being located opposite to the first substrate side. The second substrate side is connected to a first baseplate side and the baseplate also includes a second baseplate side being located opposite to its first baseplate side and being adapted for coming in contact with the cooler. The cooler includes a first casing component and a second casing component. The baseplate side is equipped with a cooling area that is surrounded by a connecting area.