Copper Bus Bar Strip Geometry for Crack-Resistant Edgewise Bending
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Solution Overview
Problem
Existing copper materials face challenges in edgewise bending, particularly for thick bus bars, due to insufficient bendability, leading to cracks and non-uniform shapes, which degrade the quality of components for electric and electronic devices.
Innovation Solution
A copper strip designed for edgewise bending with specific thickness, width, and area ratios, incorporating elements like Mg, Ca, and Zr to enhance strength and bendability, and a slit face to distribute stress evenly, reducing the risk of cracks and wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of copper material increases to reduce current density and diffuse heat, then electrical conductivity and heat dissipation improve, but edgewise bendability deteriorates and cracks occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the copper strip within 1-10mm and adjusting the area ratio B/(A+B) to 10-100% in the critical corner region. This optimization allows thick copper strips to achieve both good electrical conductivity and sufficient edgewise bendability without cracking, resolving the contradiction between reliability and ease of manufacture.
Solution Approach 2:
The patent applies local quality by focusing on the corner portion geometry between the surface and end face. By controlling the area ratio B/(A+B) specifically in the corner region (square region with side length 1/10 of thickness), the patent creates a local structural optimization that prevents stress concentration during edgewise bending, enabling thick strips to bend without cracks while maintaining overall electrical conductivity.
2Adaptability or versatility
If severe edgewise bending is performed to achieve connection in narrow spaces, then spatial adaptability improves, but cracks occur and shape uniformity deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the corner geometry (controlling area ratio B/(A+B) to 10-100%) before the edgewise bending process. This preliminary structural preparation ensures that when severe bending is performed to achieve connection in narrow spaces, the pre-conditioned corner portions resist crack formation and maintain shape uniformity, enabling high spatial adaptability without sacrificing manufacturing precision.
3Loss of energy
If the thickness of copper material increases, then current density reduction and heat diffusion improve, but stress concentration increases and cracks occur during bending
Solution Approach 1:
The patent applies parameter changes by optimizing the area ratio B/(A+B) in the corner region to 10-100% for strips with thickness 1-10mm. This parameter optimization redistributes stress during bending, allowing thick strips to achieve good heat diffusion while maintaining resistance to cracking through improved stress distribution in critical regions.
Data Source
AI summary
A copper strip for edgewise bending can be edgewise-bent under a condition that a ratio R/W of a bending radius R to a width W is 5.0 or less. In the copper strip, a thickness t is in a range of 1 mm or more and 10 mm or less, and area ratio B/(A+B) is in a range of more than 10% and 100% or less in a square region where the length of one side is 1/10 of the thickness t, where an intersection of a straight line which contacts a surface and is parallel to a width direction and a straight line which contacts an end face and is perpendicular to the width direction is used as a reference in a cross section orthogonal to a longitudinal direction, A is an area where copper is present, and B is an area where copper is not present.