High Voltage Fringe-Effect Capacitor Design
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Solution Overview
Problem
Conventional multilayer chip capacitors face challenges in achieving high voltage ratings and capacitance values while maintaining a small form factor, due to voltage breakdown issues and limited bandwidth, especially in medical devices like cardiac pacemakers.
Innovation Solution
The design incorporates non-overlapping electrodes with a non-planar boundary and varying electrode gaps to increase effective surface area and capacitance, utilizing fringe-effect capacitance to achieve higher breakdown voltages and capacitance values in a smaller package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the distance between plates is minimized to increase capacitance per unit volume, then capacitance increases, but the capacitor cannot operate at its rated voltage without dielectric breakdown
Solution Approach 1:
The patent transitions from conventional parallel-plate overlapping electrodes to non-overlapping electrodes with fringing fields, effectively changing the dimensional relationship between electrodes. The electrodes extend beyond the opposing electrode edges, creating capacitive coupling in the lateral dimension rather than relying solely on vertical overlap, thereby increasing capacitance without reducing plate separation distance.
Solution Approach 2:
The patent changes the geometric parameters of the electrode configuration by introducing non-overlapping regions with fringing fields. This parameter change allows the electric field to extend laterally beyond the electrode edges, increasing the effective capacitance area without requiring the plates to be closer together, thus maintaining dielectric strength while increasing capacitance per unit volume.
2Reliability
If the operating voltage of the capacitor increases, then the capacitor can handle higher voltages, but the maximum capacitance achievable within a fixed package size drops
Solution Approach 1:
By extending electrodes laterally beyond opposing electrodes and utilizing fringing fields, the patent increases the effective capacitance area in the lateral dimension. This allows higher capacitance values to be achieved within the same package size even when larger plate separations are required for higher voltage operation.
Solution Approach 2:
The patent employs a composite structure combining overlapping electrode regions (for baseline capacitance) with non-overlapping fringing field regions (for additional capacitance). This composite electrode configuration maximizes capacitance within the fixed package size while maintaining the voltage rating requirements.
3Device complexity
If conventional overlapping parallel-plate electrodes are used, then the capacitor structure is simple, but series resistance and inductance dominate at high frequencies, limiting bandwidth
Solution Approach 1:
The patent extends electrodes laterally beyond opposing electrodes to create fringing field regions. This dimensional change increases the effective capacitance area and reduces equivalent series inductance by distributing current paths more effectively, thereby extending the useful bandwidth into the high-frequency range while maintaining a relatively simple layered structure.
4Reliability
If the capacitor is designed for high voltage operation with adequate plate separation, then dielectric breakdown is prevented, but the physical size of the capacitor increases
Solution Approach 1:
The patent changes the geometric parameters by introducing non-overlapping electrode regions with fringing fields. This allows the electric field to be utilized more efficiently in the lateral direction, increasing capacitance without requiring proportionally larger plate separation distances, thereby maintaining compact size while achieving high voltage operation.
Solution Approach 2:
The composite electrode structure combines overlapping and non-overlapping regions, maximizing capacitance density while maintaining adequate separation for voltage rating. This allows high voltage operation in a compact package by utilizing both vertical and lateral field components.
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 allows for higher breakdown voltages and capacitance values in a compact form factor, reducing series resistance and inductance, thereby enhancing filtering capabilities, particularly in high-frequency applications.
Implementation Method 1
The electric field forms between electrically opposed electrodes when a voltage is applied to the capacitor terminals
Implementation Method 2
A capacitor is an electronic component that stores electrical energy in the form of an electric field
Implementation Method 3
utilizing fringe-effect capacitance to achieve higher breakdown voltages and capacitance values in a smaller package
Data Source
AI summary
A multilayer chip capacitor includes electrodes comprised of numerous, closely spaced conductive layers. Adjacent conductive layers are essentially non-overlapping, so that fringe capacitance between opposing electrodes provides substantially all of the capacitance. The conductive layers may be shaped to form a non-planer boundary between electrodes. An additional high frequency integrated capacitor is formed from external electrode plates. The non-planar electrode boundary principle is also applied to discoidal capacitors in the form of a non-concentric electrode boundary.