Multilayer Bus Bar Soldering Pattern for Inner-Layer Attachment
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Solution Overview
Problem
In aerospace power electronic converter designs, high switching frequencies lead to current crowing in conventional bus bars, making reliable soldering of multilayer components challenging due to the skin-depth issue, where inner layers are difficult to reach and soldering quality is poor, resulting in high contact resistance and potential overheating.
Innovation Solution
A multi-layer bus bar assembly with a unique soldering pattern on each conductive layer, featuring cutouts with specific through holes and slots that allow joining material to flow and engage multiple layers effectively, improving solder joint quality by creating a staircase pattern around the capacitor pin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional through-hole rectangle capacitors and conventional multilayer copper bus bar are used, then the structure is simple and easy to manufacture, but the soldering quality is poor where the inner layers are barely attached to the capacitor pins
Solution Approach 1:
The conductive layers are segmented into multiple discrete layers (first conductive layer, second conductive layer, etc.) with through-holes positioned at different locations in each layer. This segmentation allows solder to access and attach to capacitor pins at multiple levels, improving soldering quality of inner layers while maintaining a manageable structural complexity through modular layer design.
Solution Approach 2:
The invention transitions from a conventional single-plane soldering approach to a multi-dimensional stacked conductive layer structure. Through-holes are distributed across multiple vertical layers, creating a three-dimensional soldering pathway that enables access to inner layers without significantly increasing manufacturing complexity.
2Power
If the switching frequency is increased to reduce DC link capacitance, then the power density is improved, but current crowding occurs in the DC link where electrical current only flows to the surface of copper layers to certain depth (skin-depth)
Solution Approach 1:
The copper structure is divided into multiple thin conductive layers stacked vertically, each carrying a portion of the total current. This segmentation distributes the current across multiple parallel pathways, reducing current density in each individual layer and mitigating skin-effect-related current crowding, thereby improving reliability while maintaining high power density.
Solution Approach 2:
The invention uses a composite structure of multiple insulated copper layers, combining the high conductivity of copper with the insulating properties of intermediate layers. This composite arrangement creates multiple current pathways that reduce skin-depth limitations, improving current distribution and reliability without sacrificing power density.
3Ease of operation
If conventional soldering methods are used on multilayer components, then the top most layer is easily accessible for soldering, but the inner layers are difficult to reach and soldering quality is poor
Solution Approach 1:
The conductive structure is segmented into multiple layers with through-holes strategically positioned in each layer. This segmentation creates multiple access points for solder, allowing conventional soldering methods to effectively reach and attach to capacitor pins at different depths, improving inner layer attachment while maintaining ease of operation.
Solution Approach 2:
The through-holes in each conductive layer act as intermediaries that facilitate solder access to capacitor pins. These intermediary pathways enable solder to reach inner layers without requiring complex soldering techniques, bridging the gap between easy accessibility and good inner layer attachment.
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
Enhances soldering quality by ensuring all layers are securely attached, reducing contact resistance and preventing overheating, thus improving the reliability and efficiency of power electronic converters.
Implementation Method 1
The soldering pattern includes a first through hole that extends circumferentially at least partway around the electrical connection pin relative to the axis and a second through hole located radially outward from the first through hole
Data Source
AI summary
An electrical assembly, such as a multi-layer bus bar, includes an electrical connection pin and a plurality of electrically conductive layers. Each of the electrically conductive layers is formed to define a cutout therein to receive the electrical connection pin and allow access for joining material to join the electrical connection pin with the plurality of electrically conductive layers. Each of the cutouts is formed to include a first through hole arranged around the electrical connection pin and a second through hole located radially outward of the first through hole.