Solid Electrolytic Capacitor Differential Dielectric Thickness
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Solution Overview
Problem
Conventional solid electrolytic capacitors, particularly those using in situ polymerized polymers, tend to fail at high voltages and experience significant capacitance loss due to humidity, limiting their performance in high voltage environments.
Innovation Solution
A solid electrolytic capacitor design featuring a sintered porous anode with a dielectric layer of differential thickness and a solid electrolyte composed of pre-polymerized conductive polymer particles and hydroxy-functional nonionic polymer, which enhances breakdown voltage and wet-to-dry capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional solid electrolyte is used, then manufacturing process is simple, but capacitance fluctuation due to humidity is large
Solution Approach 1:
The patent modifies the electrolyte composition by adding hydroxy-functional nonionic polymers (polyethylene glycol and/or polypropylene glycol) to the conventional intrinsically conductive polymer formulation. This parameter change maintains the simplicity of the coating process while dramatically improving capacitance stability in humid conditions, achieving at least 80% wet-to-dry capacitance ratio.
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 capacitor achieves high breakdown voltage and maintains a high percentage of its wet capacitance, even in humid conditions, making it suitable for high voltage applications with minimal capacitance loss.
Implementation Method 1
a first stage in which the anode is anodically oxidized at a first forming voltage and a second stage in which the anode is anodically oxidized at a second forming voltage that is greater than the first forming voltage
Implementation Method 2
coating the dielectric layer with a dispersion that contains a plurality of pre-polymerized conductive polymer particles
Data Source
AI summary
A capacitor for use in relatively high voltage environments is provided. During formation, anodization may be carried out in a manner so that the dielectric layer possesses a relatively thick portion that overlies an external surface of the anode and a relatively thin portion that overlies an interior surface of the anode. In addition to employing a dielectric layer with a differential thickness, the solid electrolyte is also formed from the combination of pre-polymerized conductive polymer particles and a hydroxy-functional nonionic polymer.