Layered Insulated Wire Coating for Bend-Resistant Adhesion
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Solution Overview
Problem
Insulated wires used in electrical and electronic equipment face challenges in maintaining adhesion between the insulating film and conductor, especially during complex bending processes with small radii, and require improved flexibility to prevent cracking.
Innovation Solution
The insulated wire is formed with an inner layer of one or more thin insulating layers (less than 5 μm) and an outer layer composed of multiple insulating layers with an average thickness of 5 μm or more, achieved by repeated application and baking of resin varnish, ensuring a maximum thickness to minimum thickness ratio of 2.5 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating film is made thicker to improve insulation properties, then insulation performance is improved, but flexibility deteriorates and cracks occur during bending
Solution Approach 1:
The insulating film is segmented into multiple thin layers (first insulating layer, second insulating layer, third insulating layer) rather than a single thick layer. Each layer has optimized thickness (e.g., 1-3 μm for first layer, 3-7 μm for second layer, 1-5 μm for third layer) to balance insulation performance with flexibility during bending operations.
Solution Approach 2:
Different regions of the insulating film have different thickness characteristics. The first insulating layer in contact with the conductor has controlled thickness variation (maximum/minimum ratio ≤ 2.5) for adhesion, while outer layers provide additional insulation. This local differentiation optimizes both flexibility and insulation in respective zones.
2Ease of operation
If the insulating film is made thinner to improve flexibility, then bending performance is improved, but adhesion deteriorates and peeling occurs
Solution Approach 1:
The insulating film is divided into multiple functional layers, with the first insulating layer specifically optimized for adhesion (thickness 1-3 μm, max/min ratio ≤ 2.5) and outer layers providing mechanical protection and additional insulation. This segmentation allows each layer to specialize in one function.
Solution Approach 2:
The insulating film uses composite structure with at least two different resins (e.g., polyimide and polyamideimide) in different layers. This composite approach provides both strong adhesion to the conductor and sufficient flexibility for bending, while maintaining insulation properties.
3Device complexity
If a single-layer insulating film is used to simplify structure, then manufacturing is simplified, but adhesion and flexibility cannot be simultaneously optimized
Solution Approach 1:
The insulating film is segmented into three layers with distinct thickness ranges and material compositions. The first layer (1-3 μm) optimizes adhesion, the second layer (3-7 μm) provides mechanical strength and flexibility, and the third layer (1-5 μm) adds insulation. This segmentation enables simultaneous optimization of adhesion and flexibility.
Solution Approach 2:
Each layer has locally optimized properties: the first layer has controlled thickness uniformity (max/min ratio ≤ 2.5) for adhesion, while outer layers have different thickness specifications for flexibility and insulation. This local quality differentiation achieves performance optimization that a single uniform layer cannot provide.
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
The solution provides enhanced adhesion and flexibility, enabling the wire to withstand complex bending without peeling or cracking, thereby improving the performance of coils, rotating electrical machines, and electronic equipment.
Implementation Method 1
an insulating film formed by repeating application and baking of a resin varnish on an outer periphery of the conductor
Data Source
AI summary
An insulated wire including a conductor and an insulating film formed by repeating application and baking of a resin varnish on an outer periphery of the conductor,wherein the insulating film comprises an inner layer that is configured by one or more insulating layers each having a thickness of less than 5 μm, and an outer layer that is outside the inner layer and configured by a plurality of insulating layers, andwherein among the insulating layers configuring the outer layer, a thickness of an insulating layer in contact with the inner layer is 5 μm or more, and an average of thicknesses of the respective insulating layers configuring the outer layer is 5 μm or more.