Solid Electrolytic Capacitor Flush Dielectric Layer
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Solution Overview
Problem
Solid electrolytic capacitors face issues with increased leak current and short circuits due to gaps between the dielectric coating and solid electrolyte layer, caused by thermal expansion differences and moisture ingress, especially during the injection molding and aging processes.
Innovation Solution
A solid electrolytic capacitor design featuring a dielectric coating and solid electrolyte layer with end faces formed approximately flush with each other, covered with a thermoplastic insulating layer to prevent gaps and enhance reliability, and a manufacturing method that includes forming a one-piece dielectric coating, precoat layer, and conductive polymer layer using electrolytic polymerization, followed by laser removal of burrs and application of a cathode lead layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the dielectric coating and solid electrolyte layer are formed separately on the anode lead member, then the manufacturing process can be simplified, but gaps between the layers occur due to thermal expansion differences during injection molding and aging, causing increased leak current and short circuits
Solution Approach 1:
The patent merges the dielectric coating and solid electrolyte layer into a single integrated structure formed by electrolytic polymerization. The anode lead member serves as both the substrate for dielectric coating formation and the electrode for subsequent electrolytic polymerization, creating a unified layered structure that eliminates gaps between separate layers while maintaining manufacturing simplicity.
Solution Approach 2:
The patent uses composite material formation where the dielectric coating (oxide layer) and solid electrolyte (conductive polymer layer) are sequentially deposited on the anode lead member. This composite structure ensures proper adhesion and eliminates thermal expansion mismatches that would occur with separately formed layers, preventing gap formation during injection molding and aging processes.
2Productivity
If laser beam is used to remove burrs of the conductive polymer layer, then productivity is improved, but the heat from the laser beam causes the end faces of the dielectric coating and solid electrolyte layer to separate, increasing leak current
Solution Approach 1:
The patent applies local quality by using laser beam only for removing burrs from the side surface of the anode lead member, while carefully controlling the laser parameters to avoid heating the end faces where the dielectric coating and solid electrolyte layer are formed. This localized application of laser energy maintains productivity while preventing thermal damage to the critical layered structure.
Solution Approach 2:
The patent performs preliminary actions by forming the dielectric coating and solid electrolyte layer with sufficient excess material during the electrolytic polymerization process, allowing for subsequent burr removal without compromising the integrity of the end faces. The layered structure is formed with built-in redundancy that accommodates the burr removal step.
3Volume of moving object
If the end faces of the dielectric coating and solid electrolyte layer are formed flush with each other, then the capacitor size is reduced, but gaps occur between the layers due to thermal expansion differences, causing short circuits
Solution Approach 1:
The patent merges the formation of the dielectric coating and solid electrolyte layer into a single integrated electrolytic polymerization process, where both layers are formed simultaneously on the anode lead member. This ensures perfect alignment and flush end faces without gaps, reducing capacitor size while maintaining reliability through the unified formation 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 leak current and short circuit occurrences by ensuring the dielectric coating and solid electrolyte layer remain intact and protected from thermal and humidity-related stresses, maintaining capacitor reliability and performance.
Implementation Method 1
The dielectric coating 5 is formed by oxidizing the surfaces of the anode element 3 and the anode lead member 4 with an anodic oxidation method
Implementation Method 2
the monomer is polymerized on the dielectric coating 5 to form the solid electrolyte layer 7
Implementation Method 3
a laser beam 31 is radiated to the conductive polymer layer 7b formed on the surface of the anode lead member 4 to remove the conductive polymer layer 7b
Data Source
AI summary
A solid electrolytic capacitor of the present invention includes a capacitor element having an anode element, an anode lead member projecting from the anode element, a dielectric coating formed on a surface of the anode element and a surface of the anode lead member near the anode element, a solid electrolyte layer formed on the dielectric coating, and a cathode lead layer formed on the solid electrolyte layer; and an insulating enclosure member for coating the outer periphery of the capacitor element. End faces of the dielectric coating and the solid electrolyte layer formed on the anode lead member are formed approximately flush with each other. The end faces of the dielectric coating and the solid electrolyte layer are covered with an insulating layer made of a thermoplastic insulating material.