Solid Electrolytic Capacitor Moisture Barrier Design
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Solution Overview
Problem
Conventional solid electrolytic capacitors using in situ polymerized polymers exhibit high leakage current and fail at high voltages, and their thermal stability decreases when exposed to humid environments due to polymer oxidation.
Innovation Solution
A solid electrolytic capacitor design featuring a sintered porous anode body, a dielectric, a conductive polymer layer as the solid electrolyte, and a moisture barrier with a conjugated polymer that has high specific conductivity and is hydrophobic, reducing water absorption and enhancing electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If in situ polymerized polymers are used as solid electrolyte, then low ESR is achieved, but high leakage current and failure at high voltages occur
Solution Approach 1:
The patent uses a composite structure combining a conductive polymer layer (for low ESR) with a moisture barrier layer containing hydrophobic materials (for reliability). This composite approach allows the capacitor to achieve both low energy loss and high reliability by combining materials with complementary properties.
2Reliability
If PEDOT:PSS dispersions are used as solid electrolyte, then improved electrical properties are achieved, but thermal stability decreases due to polymer oxidation in humid environments
Solution Approach 1:
The patent introduces a moisture barrier layer as an intermediary between the conductive polymer electrolyte and the external humid environment. This barrier layer contains hydrophobic materials that prevent moisture from reaching the polymer, thereby maintaining thermal stability while preserving the electrical properties of the PEDOT:PSS dispersion.
3Loss of energy
If conductive polymer layer is applied to improve electrical properties, then low ESR is achieved, but water absorption increases in humid conditions
Solution Approach 1:
The patent segments the solid electrolyte structure into two distinct functional layers: a conductive polymer layer (for low ESR) and a moisture barrier layer (for preventing water absorption). This segmentation allows each layer to optimize its specific function without compromising the other, achieving both low energy loss and resistance to moisture.
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 maintains low equivalence series resistance, leakage current, and capacitance stability even at high temperatures and humid conditions, with minimal water absorption, ensuring reliable performance in various environmental conditions.
Implementation Method 1
a moisture barrier with a conjugated polymer that has high specific conductivity and is hydrophobic, reducing water absorption
Implementation Method 2
a solid electrolyte that overlies the dielectric, wherein the solid electrolyte includes a conductive polymer layer
Data Source
AI summary
A solid electrolytic capacitor containing a capacitor element is provided. The capacitor element contains a sintered porous anode body, a dielectric that overlies the anode body, a solid electrolyte that overlies the dielectric, wherein the solid electrolyte includes a conductive polymer layer, and a moisture barrier that overlies the conductive polymer layer.