Capacitive Structure with Stress-Reducing Mesh Layer
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Solution Overview
Problem
Current capacitive structures face a trade-off between maximum capacitance and working voltage, with high capacitance values typically limited to lower voltages and prone to failure due to piezoelectric/electrostrictive stress cracking, especially in larger, higher voltage components.
Innovation Solution
A capacitive structure with a stress-reducing layer having an open mesh structure, formed by blending an organic material with a dielectric material and sintering to create a sponge-like layer that reduces crack transmissibility, allowing for higher capacitance at higher working voltages without significant failure rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode count is increased to achieve higher capacitance, then the capacitance value increases, but the working voltage decreases and reliability deteriorates due to piezoelectric/electrostrictive stress cracking
Solution Approach 1:
The capacitor is divided into multiple components stacked together, with each component containing a subset of the total electrode layers. This segmentation allows the stress to be distributed across multiple independent units, reducing the likelihood of catastrophic failure in any single component while maintaining high total capacitance through the combined effect of all components.
Solution Approach 2:
A stress reducing layer is introduced as an intermediary between adjacent components in the stack. This layer absorbs and redistributes piezoelectric/electrostrictive stresses that arise during operation, preventing stress concentration at component interfaces and thereby reducing crack initiation and propagation, which improves reliability while allowing higher capacitance values.
2Stress or pressure
If the spacing between electrodes is increased to achieve higher working voltage, then the working voltage increases, but the capacitance value decreases
Solution Approach 1:
By segmenting the capacitor into multiple components stacked in series, each component can be designed with optimized electrode spacing appropriate for high voltage operation. The series configuration allows the total working voltage to be distributed across multiple components, while the cumulative capacitance of all components achieves the desired high capacitance value, thus resolving the trade-off between voltage and capacitance.
Solution Approach 2:
The stress reducing layer acts as a composite material with specific mechanical and electrical properties that enable it to withstand high voltages while maintaining electrical connectivity. This composite structure allows the capacitor to achieve both high working voltage and high capacitance by combining layers with different functional properties in a unified device.
3Volume of moving object
If the package size is reduced to achieve smaller form factor, then the package size decreases, but the heat dissipation capability deteriorates
Solution Approach 1:
The capacitor adopts a stacked configuration where multiple components are arranged vertically in series, utilizing the depth dimension rather than increasing footprint area. This dimensional approach allows high voltage and high capacitance to be achieved within a compact package by stacking thin-layered components, thereby maintaining small form factor while the stress reducing layers facilitate heat dissipation through their intermediate positioning and material properties.
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
Enables the construction of capacitors with higher capacitance values at higher working voltages, such as 500V and 1µF in a small package size, while reducing failure rates by absorbing electrical stress and preventing crack propagation.
Implementation Method 1
a stress reducing layer having a supporting structure with an open mesh in which air acts to reduce the transmissibility of cracks through the stress reducing layer
Data Source
Figure 1~2
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AI summary
The invention relates to a capacitive structure comprising: first and second components, at least one component comprising a plurality of capacitive layers of a dielectric, each layer arranged between electrodes of different polarity, wherein the first and second components are arranged in a stack separated by a stress reducing layer (18) having a supporting structure with an open mesh in which air acts to reduce the transmissibility of cracks through the stress reducing layer.