Multi-layer Capacitor Film Segmentation for High Voltage Endurance
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Solution Overview
Problem
Current film capacitors lack sufficient electrically insulating characteristics at high temperatures, making it difficult to achieve high voltage endurance, especially in applications where high voltages are applied across a broad temperature range.
Innovation Solution
A film for capacitors comprising multiple layers of thermoplastic resin with an oxygen gas permeability coefficient ratio (Cmo/Cmu) of 1.1 or higher, where Cmu is the permeability of the multi-layer film and Cmo is the permeability of a uniform single-layer equivalent, and a thickness of 1 to 35 μm, produced through a process involving melting, laminating, and co-extruding of the resin composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer film is used, then the film structure is simple and easy to manufacture, but the electrically insulating characteristics at high temperature are insufficient
Solution Approach 1:
The film is divided into multiple layers (at least 3 layers) with different thicknesses, where the first and third layers have a first thickness and the second layer has a second thickness different from the first. This segmentation improves electrically insulating characteristics by creating a multi-layer structure that better resists high-temperature breakdown while maintaining manufacturability through systematic layer design.
Solution Approach 2:
Different layers are assigned different thicknesses to optimize local properties: the first and third layers have one thickness while the second layer has a different thickness. This local variation in thickness allows each layer to perform its specific function optimally, enhancing overall electrically insulating characteristics without requiring complete structural redesign.
2Reliability
If the film thickness is increased, then the voltage endurance improves, but the film becomes thicker and may affect device integration
Solution Approach 1:
Instead of using a single thick layer, the film is segmented into multiple thinner layers with different thicknesses. The total thickness is distributed across layers, where the first layer has a first thickness, the second layer has a second thickness (different from the first), and the third layer has a first thickness again. This segmentation achieves the required voltage endurance while keeping individual layer thicknesses manageable for device integration.
Solution Approach 2:
The film uses a composite multi-layer structure combining layers of different thicknesses to achieve superior voltage endurance. This composite approach allows optimization of each layer's contribution to overall performance, achieving high voltage endurance without requiring excessive total thickness that would complicate device integration.
3Reliability
If a multi-layer structure with different thicknesses is used, then the electrically insulating characteristics improve, but the manufacturing precision requirements increase
Solution Approach 1:
The film is segmented into multiple layers with different thicknesses, where the first and third layers share a common first thickness and the second layer has a second thickness. This systematic segmentation provides clear manufacturing targets for each layer, making it easier to control thickness variations compared to arbitrary multi-layer designs, thereby improving electrically insulating characteristics while managing manufacturing precision requirements.
Solution Approach 2:
Different thicknesses are assigned to different layers based on their specific functional requirements. The first layer has a first thickness optimized for its function, the second layer has a second thickness optimized for its function, and the third layer has a first thickness matching the first layer. This local optimization approach allows each layer to be manufactured with precise thickness control tailored to its specific role, improving overall electrically insulating characteristics.
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 multi-layer film exhibits enhanced electrically insulating characteristics and high voltage endurance at high temperatures, outperforming equivalent single-layer films by improving resistance to defects and dielectric breakdown.
Implementation Method 1
oxygen gas permeability coefficient of the film (Cmu) and an oxygen gas permeability coefficient of an equivalent film (Cmo) obtained when the film for the capacitor is formed in the form of a uniform single layer, satisfy a relational expression: Cmo/Cmu≥1.1
Data Source
AI summary
A film for a capacitor having a plurality of layers, the film for capacitors satisfying the following relational expression (1): Cmo/Cmu≥1.1 wherein Cmu is an oxygen gas permeability coefficient of the film for the capacitor, and Cmo is an oxygen gas permeability coefficient of an equivalent film that would be obtained if the film for the capacitor were to be formed as a uniform single layer, and having a thickness of 1 to 35 μm.