Asymmetric Surface Roughness in Flat Rectangular Coil Conductors
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Solution Overview
Problem
Insulated flat rectangular conductors face issues with adhesion between the insulating film and the conductor, leading to defects when bent into a coil shape, as foreign substances easily adhere to the roughened surface, causing non-uniform coating and peeling problems.
Innovation Solution
A method where one surface of the flat rectangular conductor is roughened to increase contact area with the insulating film, while the opposite surface remains smoother to prevent foreign substance adhesion, with surface roughness ranging from 0.14 µm to 1.5 µm for the first surface and 0.07 µm or less for the second surface, enhancing adhesion and reducing film defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire flat rectangular conductor surface is roughened to improve adhesion, then adhesion between conductor and insulating film is improved, but foreign substances easily adhere and remain on the surface causing insulating film defects
Solution Approach 1:
The invention applies different surface qualities to different regions of the conductor. The first surface (to be wound inside the coil) is roughened with Ra of 0.03 µm or more to enhance adhesion, while the second surface (outer surface) is kept smooth with Ra of 0.03 µm or less to prevent foreign substance adhesion. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
Solution Approach 2:
The invention creates an asymmetric surface configuration where the two surfaces of the flat rectangular conductor have different roughness characteristics. The first surface has higher roughness (Ra ≥ 0.03 µm) for adhesion enhancement, while the second surface has lower roughness (Ra ≤ 0.03 µm) for contamination resistance. This asymmetric design allows simultaneous optimization of both adhesion and cleanliness.
2Strength
If the surface is roughened to increase contact area, then adhesion is improved, but uniform coating of the insulating film becomes difficult
Solution Approach 1:
The invention applies different surface qualities to different regions of the conductor. The first surface (to be wound inside the coil) is roughened with Ra of 0.03 µm or more to enhance adhesion, while the second surface (outer surface) is kept smooth with Ra of 0.03 µm or less to prevent foreign substance adhesion. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
3Shape
If the conductor is bent into a coil shape, then the coil structure is formed, but the insulating film peels off due to insufficient adhesion
Solution Approach 1:
The invention applies different surface qualities to different regions of the conductor. The first surface (to be wound inside the coil) is roughened with Ra of 0.03 µm or more to enhance adhesion, while the second surface (outer surface) is kept smooth with Ra of 0.03 µm or less to prevent foreign substance adhesion. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
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 configuration improves adhesion between the conductor and insulating film, reducing film defects and peeling issues, even under compressive stress during coil winding, by increasing the contact area and minimizing foreign substance adherence.
Implementation Method 1
the first surface is rougher than the second surface... a contact area between the first surface and the insulating film increases, due to the first surface that is rougher than the second surface
Data Source
Figure 1~2
Figure 3~4
AI summary
There is provided an insulated flat rectangular conductor (10, 20) including: a flat rectangular conductor (11); and an insulating film (15) coating the flat rectangular conductor (11), in which the flat rectangular conductor (11) has a first surface (12a) and a second surface (12b) opposite to the first surface (12a), and the first surface (12a) is rougher than the second surface (12b).