Hermetically Sealed Wet Electrolytic Capacitor Lid Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wet electrolytic capacitors face issues with liquid electrolyte leakage due to gas buildup, leading to corrosion of hermetic seals and high DC leakage currents, despite the use of liquid seals, indicating a need for an improved hermetic sealing mechanism.
Innovation Solution
A hermetically sealed wet electrolytic capacitor design featuring a lid assembly with a glass-to-metal seal and a flowable insulative liquid sealant that covers a substantial portion of the inner surfaces, preventing electrolyte contact and enhancing leakage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hermetic seal is used to prevent electrolyte leakage, then sealing reliability is improved, but the hermetic seal itself becomes susceptible to corrosion by the liquid electrolyte
Solution Approach 1:
The patent introduces a liquid sealant as an intermediary substance between the hermetic seal and the electrolyte. This liquid sealant forms a barrier that prevents direct contact between the electrolyte and the hermetic seal, thereby eliminating the corrosion problem while maintaining the hermetic sealing function.
Solution Approach 2:
The sealing system is divided into two distinct functional layers: the hermetic seal provides the primary gas-tight barrier, while the liquid sealant provides a secondary protective layer that specifically addresses electrolyte corrosion. This segmentation allows each component to specialize in its optimal function.
2Reliability
If elastomeric rings are compressed to form a liquid seal, then liquid sealing is improved, but a small amount of electrolyte can still leak through causing high DC leakage current
Solution Approach 1:
The patent changes the physical state and properties of the sealing material from solid elastomeric rings to a flowable liquid sealant. This parameter change allows the sealant to dynamically adapt to surface irregularities and maintain effective sealing under varying operating conditions, preventing electrolyte leakage.
Solution Approach 2:
The liquid sealant provides dynamic sealing capability, allowing the seal to adjust and flow to maintain contact and prevent leakage. This is particularly effective under thermal cycling and mechanical stress conditions where rigid or pre-compressed seals may fail.
3Ease of manufacture
If conventional polymeric seals are used at terminal wire protrusions, then ease of manufacture is improved, but gas pressure buildup causes leaks around the seals
Solution Approach 1:
The patent employs a composite sealing approach combining the hermetic seal (glass-to-metal or metal-to-metal), the liquid sealant (insulative material), and the cathode material coating on the casing. This multi-material composite structure addresses both manufacturing ease and reliability under gas pressure conditions.
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 design effectively reduces electrolyte leakage and DC leakage currents, maintaining the capacitor's electrical integrity and reliability by ensuring a robust hermetic seal, even under operating temperatures.
Implementation Method 1
A liquid seal coats a substantial portion of the inner surface of the lid and the hermetic seal. The liquid seal contains an insulative sealant material.
Implementation Method 2
A hermetic seal is positioned within the orifice of the lid, the hermetic seal having a lower surface that faces toward the interior of the casing.
Implementation Method 3
an electrochemically active cathode material is located on at least a portion of the sidewall... An electrolyte is in electrical contact with the anode and the electrochemically active material.
Implementation Method 4
The anode is formed from a porous anode body that contains a dielectric layer
Data Source
AI summary
A wet electrolytic capacitor that contains a hermetically sealed lid assembly is disclosed. More specifically, the lid assembly contains a lid (e.g., titanium) that defines an internal orifice. A conductive tube may extend through the orifice that is of a size and shape sufficient to accommodate an anode lead. An insulative material is also provided within the orifice to form a hermetic seal (e.g., glass-to-metal seal), such as between the conductive tube and the lid. The lid assembly also includes a liquid seal that is formed from a sealant material. The liquid seal coats a substantial portion of the lower surface of the lid and hermetic seal to limit contact with any electrolyte that may leak from the casing. To help achieve such surface coverage, the sealant material is generally flowable so that it can be heated during production of the capacitor and flow into small crevices that would otherwise remains uncoated.