Electrolytic Capacitor Electrolyte Layout for Seal Durability and Low ESR
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Solution Overview
Problem
Conventional electrolytic capacitors face issues with poor permeation of sealing member deterioration preventing agents due to high viscosity electrolytic solutions, leading to sealing member cracking and evaporation at high temperatures, which reduces capacitor life and increases equivalent series resistance (ESR).
Innovation Solution
Incorporating a hydrophilic compound in the electrolyte and a sealing member deterioration preventing agent immiscible with the hydrophilic compound, allowing for fast permeation into the sealing member, even in high-temperature environments, while maintaining a high electrolyte content to reduce ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer compound with polyoxyethylene group or polyoxypropylene group is used as sealing member deterioration preventing agent dissolved in electrolytic solution, then the sealing member is protected from deterioration, but the high viscosity of the electrolytic solution results in poor permeation of the sealing member
Solution Approach 1:
The patent extracts the sealing member deterioration preventing agent from the electrolytic solution and places it separately in the body case. This separation allows the agent to permeate the sealing member directly without being diluted or hindered by the high-viscosity electrolytic solution, while the electrolytic solution maintains its necessary viscosity for electrical function.
Solution Approach 2:
The patent segments the capacitor into distinct functional zones: the electrolytic solution remains confined to the capacitor element, while the sealing member deterioration preventing agent is positioned in the body case surrounding the capacitor element. This spatial segmentation enables each component to optimize its properties independently.
2Speed
If the content of sealing member deterioration preventing agent is increased to accelerate permeation, then the permeation speed increases, but the amount of electrolytic solution inside the capacitor element decreases, making it difficult to reduce ESR
Solution Approach 1:
The patent extracts the sealing member deterioration preventing agent from the electrolytic solution formulation, allowing the electrolytic solution to maintain its full intended volume and concentration without being displaced by the additive.
Solution Approach 2:
The patent uses the space between the capacitor element and the body case as an intermediary zone to hold the sealing member deterioration preventing agent. This intermediary space allows the agent to be present in sufficient quantity for rapid permeation without encroaching on the electrolytic solution volume needed for low ESR.
3Ease of operation
If a conventional electrolytic solution is used, then the capacitor operates normally, but in high-temperature environments above 150°C, the sealing member develops cracks due to insufficient permeation, causing evaporation and shortened life
Solution Approach 1:
The patent positions the sealing member deterioration preventing agent in advance in the body case, ready to rapidly permeate the sealing member when the capacitor is installed. This preliminary positioning ensures that even in high-temperature environments, the agent can quickly protect the sealing member before thermal stress causes cracking.
Solution Approach 2:
The patent changes the physical state and positioning parameters of the sealing member deterioration preventing agent from being dissolved in the electrolytic solution to being separately positioned in the body case. This parameter change enables the agent to rapidly permeate the sealing member and provides superior protection in high-temperature environments.
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 extends capacitor life and reduces ESR by effectively preventing sealing member deterioration and evaporation, even at temperatures above 150°C, by using hydrophilic compounds with boiling points of 180°C or higher and immiscible sealing member deterioration preventing agents.
Implementation Method 1
the sealing member deterioration preventing agent permeates the sealing member to suppress deterioration of the sealing member
Implementation Method 2
a sealing member deterioration preventing agent immiscible with the hydrophilic compound is arranged inside the body case
Implementation Method 3
The capacitor element may be impregnated with a predetermined liquid
Data Source
AI summary
An electrolytic capacitor 1 includes: a capacitor element 3 in which an anode foil 5 and a cathode foil 7 each having a dielectric oxide film face each other across a separator 6; a body case 2 that houses the capacitor element 3; and a sealing member 4 that seals the body case 2. An electrolyte and a hydrophilic compound are held between the anode foil 5 and the cathode foil 7. A sealing member deterioration preventing agent immiscible with the hydrophilic compound is arranged inside the body case 2.