Solid Electrolytic Capacitor Lead Frame Recesses Against Moisture Ingress
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Solution Overview
Problem
Solid electrolytic capacitors deteriorate due to exposure to oxygen and moisture, despite being covered with an exterior body, as these substances can still penetrate and affect the electrolyte layer.
Innovation Solution
The capacitors feature lead frames with buried parts that have recesses formed on their surfaces, which increase the surface area and adhesion with the exterior body, thereby lengthening the penetration path for oxygen and moisture and reducing deterioration. These recesses are created using laser light, allowing for precise control of size and shape, and are designed to accommodate insulating and conductive fillers for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitor element is covered with an exterior body, then the capacitor is protected from external damage, but oxygen and moisture can still penetrate through various paths and cause deterioration of the electrolyte layer
Solution Approach 1:
The patent segments the exterior body into multiple functional layers: a base exterior body material and a separate barrier layer with oxygen and moisture blocking properties. This segmentation allows each layer to perform its specific function - structural protection and chemical barrier protection respectively - thereby resolving the contradiction between physical protection and chemical contamination prevention.
Solution Approach 2:
The patent employs composite material structure by combining different materials with complementary properties: the exterior body uses a combination of barrier materials (such as aluminum oxide, aluminum hydroxide, titanium oxide) and resin materials. This composite approach creates an exterior body that simultaneously provides mechanical strength and chemical barrier properties against oxygen and moisture penetration.
2Ease of manufacture
If the surface of the lead frame is made smooth, then manufacturing is easier, but the adhesion with the exterior body is insufficient allowing oxygen and moisture to penetrate
Solution Approach 1:
The patent applies local quality by creating a surface structure that is locally modified only where needed - the lead frame surface is treated to have increased roughness or specific micro-structures at the interface region with the exterior body, while other parts of the lead frame maintain their original smooth surfaces for ease of manufacturing and assembly.
Solution Approach 2:
The patent implements preliminary action by pre-treating the lead frame surface before assembling the exterior body. Surface treatments such as roughening, anodization, or applying adhesion promoters are performed in advance on the lead frame, ensuring that when the exterior body is later applied, optimal adhesion is achieved without complicating the final assembly process.
3Device complexity
If conventional sealing methods are used, then the manufacturing process is simple, but oxygen and moisture still enter through the interface between the lead frame and exterior body
Solution Approach 1:
The patent introduces an intermediary substance or layer at the interface between the lead frame and exterior body. This intermediary - such as a sealant, adhesive layer, or barrier coating - fills micro-gaps and crevices at the interface, preventing oxygen and moisture penetration paths while maintaining the simplicity of the overall sealing structure and manufacturing process.
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 effectively suppresses the deterioration of the electrolyte layer, resulting in a solid electrolytic capacitor with improved reliability and performance stability by creating a longer penetration path for oxygen and moisture and enhancing adhesion with the exterior body.
Implementation Method 1
A plurality of recesses are formed on a surface of at least one of the first buried part or the second buried part by irradiating at least one of the first buried part or the second buried part with laser light a plurality of times
Data Source
AI summary
A solid electrolytic capacitor includes a capacitor element including an anode part and a cathode part, an anode lead frame electrically connected to the anode part, a cathode lead frame electrically connected to the cathode part, and an exterior body covering the capacitor element. The anode lead frame includes a first buried part that is a part of the anode lead frame and is buried in the exterior body, and the cathode lead frame includes a second buried part that is a part of the cathode lead frame and is buried in the exterior body. A plurality of recesses are formed on a surface of at least one of the first buried part or the second buried part.