Multilayer Copper Bus Bar Cutouts for Inner-Layer Soldering
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Solution Overview
Problem
In aerospace power electronic converter designs, conventional soldering methods struggle with achieving reliable connections between multilayer copper bus bars and film capacitors, particularly as the switching frequency increases, leading to current crowing and poor soldering quality due to the inner layers being difficult to reach.
Innovation Solution
A multi-layer bus bar assembly with a unique soldering pattern on each conductive layer, featuring cutouts with offset and aligned soldering patterns to facilitate better access and attachment of joining material to the electrical connection pins, enhancing the soldering quality across all layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional soldering methods are used on multilayer copper bus bars, then the top most layer is accessible for soldering, but the inner layers are difficult to reach and have poor soldering quality
Solution Approach 1:
The patent divides the soldering process into multiple sequential stages by creating offset cutouts in each conductive layer. Each layer is soldered individually through its specific cutout position, segmenting the originally inaccessible inner layers into reachable sections. This allows the soldering iron to access each layer separately, ensuring reliable soldering quality for all layers including inner layers that were previously difficult to reach.
2Power
If switching frequency is increased to reduce DC link capacitance, then power density improves, but current crowding occurs in conventional bus bars
Solution Approach 1:
The patent transitions from a conventional single-layer or flat bus bar structure to a multilayer laminated structure with conductive layers stacked in the vertical dimension. This dimensional change distributes the current flow across multiple layers, effectively reducing current density in each individual layer and eliminating current crowding effects while maintaining high power density through the compact vertical arrangement.
3Object-generated harmful factors
If multilayer conductive layers are used to reduce current crowding, then current distribution improves, but soldering access to inner layers becomes difficult
Solution Approach 1:
The patent introduces asymmetry by creating offset cutouts in each conductive layer rather than aligning them directly. Each layer's cutout is positioned at a different angular offset, creating an asymmetric pattern that progressively exposes inner layers. This asymmetric design maintains the electrical functionality of multilayer current distribution while simultaneously providing mechanical access for soldering tools to reach each layer's connection point.
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 portion arranged around the electrical connection pin and a second portion located radially outward of the first portion.