Capacitor Sealing Structure for Thermal Expansion Management
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Solution Overview
Problem
Existing capacitors face increased leakage current and deformation issues due to the expansion of sealing materials under thermal loads, which are exacerbated by the decomposition of electrolytes and pressure applied by sealing materials, leading to defective appearances and performance degradation.
Innovation Solution
A capacitor design that includes a packaging material with an opening sealed by a sealing material, featuring a through hole for terminals and a provided space between the sealing material and the capacitor element, with a stopper to absorb expansion and prevent stress on the capacitor element, thereby limiting leakage current and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing material is placed directly against the capacitor element to seal the opening, then the sealing effectiveness is improved, but the leakage current increases and the capacitor element deforms under thermal load
Solution Approach 1:
The sealing structure is segmented into multiple functional zones: a first sealing portion that directly contacts the capacitor element for sealing, and a second sealing portion that expands under thermal load to seal the opening. This segmentation allows each portion to perform its specific function without interfering with the other, preventing both leakage and deformation.
Solution Approach 2:
The first sealing portion acts as an intermediary between the capacitor element and the second sealing portion. It provides a stable sealing interface while allowing the second sealing portion to expand freely under thermal load, thus mediating between the need for effective sealing and the need to accommodate thermal expansion.
2Strength
If the sealing material is made rigid to maintain structural stability, then the sealing strength is improved, but the sealing material deforms under thermal expansion
Solution Approach 1:
The sealing material exhibits different local qualities: the first sealing portion has high rigidity and strength to maintain stable contact with the capacitor element, while the second sealing portion has higher flexibility to accommodate thermal expansion. This local differentiation of material properties resolves the contradiction between strength and thermal stability.
Solution Approach 2:
The sealing structure transitions from a static, uniformly rigid design to a dynamic structure where the second sealing portion can change its configuration in response to thermal load. The ability of the second sealing portion to expand and seal the opening dynamically maintains both strength and stability under varying thermal conditions.
3Reliability
If the sealing material is placed after the chemical conversion treatment to ensure proper sealing, then the sealing effectiveness is improved, but the chemical conversion treatment is incomplete
Solution Approach 1:
The first sealing portion is applied in advance to the capacitor element before the chemical conversion treatment. This preliminary sealing allows the chemical conversion treatment to be performed completely on all necessary surfaces, including those that would otherwise be obscured by the final sealing structure. The preliminary seal does not interfere with the treatment process.
Solution Approach 2:
The sealing process is divided into two sequential steps: first applying the first sealing portion to enable complete chemical conversion treatment, then adding the second sealing portion to achieve final sealing effectiveness. This segmentation of the sealing process resolves the contradiction between sealing effectiveness and treatment completeness.
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 leakage current and prevents deformation of the sealing material, maintaining capacitor performance and appearance even under thermal loads by absorbing expansion and inner pressure, thus enhancing reliability and longevity.
Implementation Method 1
the space between the sealing material and the capacitor element absorbs the inner pressure increased because of the vaporization of the solvent remaining in the capacitor element
Implementation Method 2
the space provided between the sealing material and the capacitor element can absorb the expansion of the sealing material caused by a thermal load
Data Source
AI summary
A capacitor has a capacitor element, a packaging material, and a sealing material. The capacitor element has an anode foil coupled to an anode terminal, a cathode foil coupled to a cathode terminal, a separator, and an electrolyte layer. The anode foil, the cathode foil and the separator are rolled together. The separator is between the anode foil and the cathode foil. The electrolyte layer is formed between the anode foil and the cathode foil. The packaging material has an opening and packages the capacitor element. The sealing material has a through hole where the anode terminal and the cathode terminal pass through and seals the opening of the packaging material. A given space is provided between the sealing material and the capacitor element. A stopper for securing the space is provided on at least one of the anode terminal and the cathode terminal.