Solid Electrolytic Capacitor Resin Structure to Prevent Lead Gaps
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Solution Overview
Problem
Solid electrolytic capacitors with exterior resins containing high filler content face issues with stress-induced breakage and easy peeling off from anode leads, leading to gaps and potential short circuits due to plating solution ingress.
Innovation Solution
A solid electrolytic capacitor design featuring a resin layer with lower filler content than the exterior resin, covering the anode lead's outer periphery, enhances adhesion and prevents gaps, thereby reducing the risk of short circuits by inhibiting plating solution ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exterior resin contains high filler content (at least 50 wt %) to increase hardness and reduce permeability, then the resistance to external stress and environmental factors is improved, but the adhesion to the anode lead deteriorates and stress-induced breakage occurs
Solution Approach 1:
The resin structure is segmented into two distinct layers: an exterior resin layer with high filler content (50-95 wt %) providing environmental protection, and an inner resin layer with low filler content (0-50 wt %) providing strong adhesion to the anode lead. This segmentation allows each layer to optimize its filler content for its specific function without compromising the other.
Solution Approach 2:
Different filler content ratios are applied to different regions of the resin structure. The exterior resin layer uses high filler content (50-95 wt %) for hardness and low permeability where environmental protection is needed, while the inner resin layer uses low filler content (0-50 wt %) for flexibility and adhesion where mechanical bonding is required.
2Stability of the object's composition
If the exterior resin contains high filler content to prevent deformation and reduce volume changes, then the dimensional stability is improved, but the susceptibility to stress-induced breakage increases
Solution Approach 1:
The resin is divided into two layers with different filler contents to separately address dimensional stability and stress resistance. The exterior layer maintains dimensional stability with high filler content, while the inner layer absorbs stress with low filler content, preventing breakage.
Solution Approach 2:
The resin structure is a composite of two resin layers with different filler compositions. This composite structure combines the dimensional stability benefits of high-filler resin with the stress-resistance benefits of low-filler resin, creating a material that exhibits both properties simultaneously.
Data Source
AI summary
A solid electrolytic capacitor that includes: a capacitor element including an anode body connected to an anode lead, a dielectric layer on a surface of the anode body, and a cathode layer opposite to the anode body via the dielectric layer; an exterior resin covering the capacitor element; a first external electrode terminal on a first outer surface of the exterior resin and electrically connected to the anode body; a second external electrode terminal on a second outer surface of the exterior resin and electrically connected to the cathode layer; and a resin layer having a lower filler content than the exterior resin and covering at least a portion of an outer periphery of the anode lead between the first outer surface of the exterior resin and the anode body.