Variable Capacitance Component Lead Axis Stray Capacitance
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Solution Overview
Problem
Variable capacitance components with comb-shaped electrodes suffer from increased stray capacitance and reduced capacitance variability, and existing methods using chemical solution deposition or sputtering limit the use of low-loss metals like Ag and Cu due to high conduction loss and impedance matching issues at high frequencies.
Innovation Solution
The solution involves arranging lead electrodes on the same axis inside the component, allowing for separate sintering of electrodes and lead portions, enabling the use of low-loss metals like copper or silver, and reducing stray capacitance by incorporating insulating portions with through-holes to house the lead electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If comb-shaped electrodes are used to increase capacitance, then capacitance is improved, but stray capacitance increases and capacitance variable rate decreases
Solution Approach 1:
The electrode structure is segmented into distinct overlapping portions and lead portions. The overlapping portions are positioned to maximize capacitance while the lead portions are routed through insulating portions to minimize stray capacitance. This segmentation allows independent optimization of capacitance generation and stray capacitance reduction.
Solution Approach 2:
Insulating portions are introduced as intermediary elements between the electrodes and the external environment. These insulating portions with through-holes guide the lead portions away from the overlapping regions, acting as mediators that prevent the formation of stray capacitance paths while maintaining electrical connectivity.
2Loss of energy
If low melting point metals like Ag and Cu are used to reduce conduction loss, then conduction loss is reduced, but sintering temperature must be lowered which sacrifices dielectric layer performance
Solution Approach 1:
The manufacturing process is segmented into two independent sintering stages: first sintering the dielectric layer at high temperature to ensure optimal performance, then separately sintering the electrode and lead portions at lower temperature to preserve low melting point metals. This process segmentation removes the temperature constraint conflict.
Solution Approach 2:
The dielectric layer is preliminarily sintered and optimized at high temperature before the electrode materials are applied and sintered. This preliminary action ensures the dielectric layer achieves its optimal performance characteristics before the low-temperature electrode sintering process, which would otherwise constrain the dielectric sintering temperature.
3Loss of energy
If electrode thickness is increased to reduce conduction loss, then conduction loss is reduced, but hillocks form after 500 nm thickness causing manufacturing failures
Solution Approach 1:
The electrode structure is segmented into thin overlapping portions and thicker lead portions. The overlapping portions maintain thin thickness to avoid hillock formation and ensure uniform lamination, while the lead portions can be thicker to reduce conduction loss in the lead paths. This segmentation allows different thickness optimizations for different functional regions.
Data Source
AI summary
A variable capacitance component includes a variable capacitance layer made of a dielectric material, a pair of electrodes that face each other via the variable capacitance layer, a pair of insulating portions that support the variable capacitance layer therebetween, and a pair of lead portions is respectively connected to the pair of electrodes, and the pair of lead portions is respectively disposed inside the pair of insulating portions, and the pair of lead portions is on a same axis that is perpendicular or substantially perpendicular to the variable capacitance layer.