Insulated Heat Extraction Assembly for Low-Resistance Power Modules
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Solution Overview
Problem
The increasing current density and higher electrical losses in semiconductor power modules for hybrid and electric vehicles lead to overheating, reducing efficiency and shortening the service life of critical components due to high thermal resistance and volume loss during soldering processes in complex structures.
Innovation Solution
A heat dissipation arrangement with three stacked joining partners, where a first solder layer is between a conductive joining partner and an insulating middle partner, and a second solder layer is between the middle partner and a conductive heat sink, forming an electrically insulated heat dissipation path, allowing for efficient thermal coupling without electrical short circuits, and using a reflow soldering process to maintain mechanical tolerances and prevent solder volume loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the semiconductor power module is miniaturized to meet installation space requirements, then the installation space is reduced, but the electrical losses increase due to higher current density in smaller supply lines
Solution Approach 1:
The power module is divided into multiple semiconductor components (IGBTs, diodes) arranged in a compact B2 bridge configuration, allowing space optimization while maintaining current carrying capacity through parallel current paths
Solution Approach 2:
The patent implements a multi-layer stacked configuration where semiconductor components, conductor tracks, and cooling structures are nested vertically. The collector conductors are arranged in a common plane with semiconductors attached, and emitter conductors are positioned below, creating a compact three-dimensional structure that reduces installation space while managing heat and current efficiently
2Temperature
If the conductor tracks are cooled at the power terminals to manage heat, then the thermal performance is improved, but the maximum temperature in the power supply increases due to electrical resistance
Solution Approach 1:
The patent applies localized cooling at the power terminals where heat generation is most intense. The collector conductors acting as heat sinks are positioned directly at the semiconductor component locations, providing targeted thermal management where it is most needed rather than uniform cooling throughout the module
Solution Approach 2:
The conductor tracks serve as dual-function intermediaries that both conduct electrical current and act as heat sinks. The collector conductors are electrically connected to external power contacts and thermally coupled to cooling structures, mediating between the semiconductor components that generate heat and the external cooling system
3Productivity
If a reflow soldering process is used to connect multiple components, then the manufacturing efficiency is improved, but the solder volume shrinkage causes the upper component to sink onto the lower component
Solution Approach 1:
The patent incorporates compensation structures in the design of the layer stack that anticipate and counteract the solder shrinkage effect before it occurs. The conductor tracks and semiconductor components are positioned with predetermined offsets that compensate for the expected sinking, ensuring proper spacing is maintained after the reflow soldering process completes
Solution Approach 2:
The design includes built-in compensation mechanisms that cushion against the harmful effect of solder shrinkage. The layer stack configuration allows for controlled movement and positioning that absorbs the shrinkage stress, preventing the upper components from sinking onto the lower components while maintaining electrical and thermal connections
4Ease of manufacture
If the solder connection surface is reduced due to volume shrinkage, then the solder joint formation is simplified, but the electrical and thermal resistance increases
Solution Approach 1:
The patent merges multiple functions into the solder joints: electrical connection, thermal conduction, and mechanical bonding. The conductor tracks are designed with increased surface area and optimized geometry that allows the solder to form robust connections that simultaneously satisfy all three requirements, compensating for the reduced connection surface area caused by shrinkage
Solution Approach 2:
The patent uses composite material structures in the conductor tracks and semiconductor components with optimized thermal and electrical properties. The materials are selected and configured to maintain high thermal and electrical conductivity even with reduced solder connection surfaces, using material composition and structure to compensate for the reduced bonding area
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 effectively decouples thermal performance from power losses, reduces electrical and thermal resistance, and ensures optimal semiconductor performance by maintaining a large connection area and cohesive casting, preventing electrical degradation under thermomechanical stress.
Implementation Method 1
The first solder layer (22A) is formed between a conductive first joining partner (24) and an electrically insulating middle joining partner (26). The second solder layer (22B) is formed between the middle joining partner (26) and a conductive second joining partner (28)... forming an electrically insulated heat dissipation path
Implementation Method 2
Heating the layer stack in a reflow soldering oven to a temperature which is higher than the second melting temperature, and then cooling the layer stack, so that during the cooling phase the second solder layer (22B) initially solidifies
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a heat extraction assembly (20) for a semiconductor power module, comprising three stacked joint partners (24, 26, 28) integrally bonded together by a first soulder layer (22A) and by a second soulder layer (22B), and a corresponding semiconductor power module comprising at least one of these heat extraction assemblies (20) and a method for bonding a layer stack consisting of three joining partners (24, 26, 28) in such a heat extraction assembly (20). The first soulder layer (22A) is formed between a first, electroconducting joining partner (24) and a central, electrically insulating joining partner (26), and the second soulder layer (22B) is formed between the central, electrically insulating joining partner (26) and a second, electroconducting joining partner (28), wherein the first joining partner (24) is a first conducting track (24A) from which heat is to be extracted and to which a first voltage potential is applied, the second joining partner (28) is a second conducting track (28A) that acts as a heat sink and to which a second voltage potential different from the first voltage potential is applied, and the central joining partner (26) is an electrically insulating intermediate layer (26A) that forms an electrically insulated heat-dissipation path between the first joining partner (24) and the second joining partner (28).