Masked Solid Electrolyte Capacitor Structure for Leakage Control
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Solution Overview
Problem
Existing solid electrolytic capacitors face issues with leakage current defects due to the entry of conductive paste during the formation of the cathode lead-out layer, particularly at the boundary between etched and unetched surfaces.
Innovation Solution
The proposed solution involves a solid electrolytic capacitor element with a valve acting metal substrate, a dielectric layer, a solid electrolyte layer, a conductive layer, and a mask that divides the substrate into anode and cathode regions. The mask's second portion covers the solid electrolyte layer to prevent conductive paste from entering potential defects, thereby reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the solid electrolyte layer is made thin to reduce stress on the insulating protective layer, then the stress on the insulating protective layer is reduced, but the layer becomes prone to defects and allows conductive paste entry causing leakage current
Solution Approach 1:
The patent applies a mask to the boundary region between the first part and second part of the anode foil before forming the cathode lead-out layer. This preliminary masking action prevents conductive paste from entering potential defect areas in the thin solid electrolyte layer, thereby preventing leakage current defects while allowing the solid electrolyte layer to be made thin for reducing stress on the insulating protective layer.
2Reliability
If the conductive paste processing accuracy is improved to prevent paste entry into defective portions, then leakage current defects are reduced, but equipment costs and management costs increase
Solution Approach 1:
Instead of improving conductive paste processing accuracy through expensive equipment upgrades, the patent employs a simple mask applied in advance to the boundary region. This preliminary protective measure prevents paste entry into defective areas without requiring high-precision paste application equipment, thereby reducing leakage current defects while avoiding increased equipment costs.
3Reliability
If the region to which conductive paste is applied is narrowed to avoid defective portions, then leakage current defects are reduced, but equivalent series resistance (ESR) increases
Solution Approach 1:
The patent uses a mask to protect only the boundary region where defects are most likely to occur, while leaving the rest of the solid electrolyte layer exposed for conductive paste application. This selective masking approach prevents paste entry into defective portions without significantly restricting the overall paste application area, thereby reducing leakage current defects while minimizing the impact on ESR.
4Reliability
If a mask is applied to cover the solid electrolyte layer to prevent paste entry, then leakage current defects are reduced, but the mask must not cover the conductive layer which is formed afterward
Solution Approach 1:
The mask is applied selectively only to the boundary region between the first part and second part of the anode foil, where defects are most likely to occur. The mask does not cover the entire solid electrolyte layer or the subsequently formed conductive layer. This localized masking approach prevents paste entry into defective areas while maintaining simplicity in the overall structure and allowing proper formation of the cathode lead-out layer.
Data Source
AI summary
A solid electrolytic capacitor element that includes: a valve acting metal substrate including a metal substrate layer and a porous layer on the metal substrate layer and having an anode terminal region and a cathode formation region; a dielectric layer on a surface of the porous layer in the cathode formation region; a solid electrolyte layer on the dielectric layer in the cathode formation region; a conductive layer on the solid electrolyte layer; and a mask having: a first portion dividing the valve acting metal substrate into the anode terminal region and the cathode formation region and in direct contact with the porous layer or in indirect contact with the porous layer via the dielectric layer, a second portion covering the solid electrolyte layer on the porous layer, and the mask does not cover the conductive layer.