PCB Capacitor Structure for High-Voltage Resonant Circuits

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Solution Overview

Problem

Current capacitors used in high-voltage, high-frequency industrial applications, such as inductive welding and electric vehicle charging, face limitations in tolerating high voltages, are bulky, costly, and have low precision, leading to increased complexity and inefficiency due to the need for multiple capacitors connected in series and parallel.

Innovation Solution

A multilayer printed circuit board technology is adapted to produce capacitors with high accuracy and tolerance for voltages up to ten kV and currents of ten amperes, featuring a dielectric layer with high permittivity and low loss characteristics, eliminating the need for capacitor banks and reducing size and cost by 70-90%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional capacitors are used in high-voltage resonant circuits, then voltage tolerance is limited to 1-2 kV, but multiple capacitors connected in series and parallel are required to achieve desired capacity values, increasing device complexity

Engineering Contradiction:
Improvevoltage toleranceVSAvoidcapacitor bank complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple capacitor functions into a single integrated device. The printed circuit board structure integrates dielectric layers, conductive patterns, and terminals into one component that can tolerate high voltages (up to 10 kV) while providing the required capacity values, eliminating the need for complex capacitor banks with multiple series and parallel connections.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses composite construction combining dielectric materials with high permittivity and low loss characteristics, conductive materials for patterns and terminals, and insulating materials for coating. This composite approach enables the single capacitor to achieve both high voltage tolerance and precise capacity control.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If traditional capacitors are used, then precision is limited with typical tolerances of 20% or 5%, but achieving lower tolerances increases cost significantly

Engineering Contradiction:
Improvecapacity value toleranceVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical capacitor construction methods with printed circuit board manufacturing techniques. The conductive patterns are created through standard PCB processes (copper deposition, etching, plating) that inherently provide precise dimensional control and low tolerance (below 2%), eliminating the need for expensive precision machining or assembly operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent achieves precise capacity control by controlling the geometric parameters of the conductive patterns and dielectric layers during PCB manufacturing. By precisely controlling trace width, spacing, layer thickness, and dielectric constant, the capacity value tolerance is reduced to below 2% using standard manufacturing capabilities.

Inventive Principle:
Principle #35Parameter changes

3Weight of stationary object

If traditional capacitors are used, then size and weight are large and bulky, but thermal management complexity increases due to required liquid-cooling systems

Engineering Contradiction:
Improvecapacitor weightVSAvoidthermal management system complexity
Core Design Contradiction:
Weight of stationary objectVSDevice complexity

Solution Approach 1:

The patent uses thin-film construction inherent to printed circuit boards, creating a capacitor with minimal thickness and compact form factor. The thin dielectric layers and conductive patterns enable high capacity density without bulk, and the flat, thin structure provides excellent thermal contact with heat sinks, allowing passive air cooling instead of complex liquid-cooling systems.

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If capacitor banks with multiple capacitors are used, then voltage tolerance is improved, but manufacturing cost and dimensions increase significantly

Engineering Contradiction:
Improvevoltage toleranceVSAvoidcapacitor dimensions
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent transitions from three-dimensional bulky capacitor assemblies to two-dimensional planar structures on printed circuit boards. The capacitor patterns are distributed across the PCB surface, utilizing the area dimension rather than volume, which dramatically reduces overall dimensions while maintaining high voltage tolerance through the integrated design.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 enables capacitors that are thinner, more efficient, and cost-effective, with precision below 2% capacity tolerance, reducing thermal management complexity and enhancing power transfer efficiency in resonant circuits.

Implementation Method 1

featuring a dielectric layer with high permittivity and low loss characteristics

Methodology Applied
Scientific EffectDielectric permittivity: Dielectric Permittivity

Implementation Method 2

Through magnetic induction on the receiving coil, it is possible to transfer electric energy to the vehicle

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

the resonance of the coil-capacitor system results in a considerable increase in the voltage across the terminals of these two elements

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3602585B1Capacitor for resonant circuits in power applications
Publication Date: 2023.08.30 POLITECNICO DI TORINO
  • EP3602585B1 patent drawingFigure 1a~1b
  • EP3602585B1 patent drawingFigure 2
  • EP3602585B1 patent drawingFigure 3a~3b

AI summary

A capacitive element is manufactured by using the multilayer printed circuit board technology. The body of the element comprises a layer of dielectric material (40) interposed between two layers of conductive material (30,32) arranged on opposite sides of the layer of dielectric material (40). Each layer of conductive material (30,32) is in turn covered, on its free side, with an external covering layer (20,22). The material for making the layer of dielectric material (40) is chosen among materials having: - a dielectric permeability εr>1, - a dielectric rigidity k>100kV/mm, and - a loss figure Df≤0.002. Furthermore, the dimensions of the layer of dielectric material (40) are greater than the dimensions of the layers of conductive material (30,32), so as to limit the edge effects that might cause discharge phenomena and make the capacitive element flexible.