Stacked Solid Electrolytic Capacitor Structure for Low ESR Adhesion
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Solution Overview
Problem
Solid electrolytic capacitors face challenges with high equivalent series resistance (ESR) and low adhesion to external electrodes, particularly in smaller sizes where thinner anodes and cathodes exacerbate these issues, making it difficult to reduce ESR and enhance electrode adhesion.
Innovation Solution
The design includes a resin molding with specific thickness ratios and configurations of exposed and non-exposed portions for the valve-action metal substrates and cathode lead-out layers, along with reverse tapered portions and recesses, to increase contact areas with external electrodes, thereby reducing ESR and improving adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the solid electrolytic capacitor is reduced, then the compactness is improved, but the equivalent series resistance (ESR) increases and adhesion to external electrodes deteriorates
Solution Approach 1:
The capacitor element is divided into multiple sheets stacked together, with each sheet containing divided anodes and cathodes. This segmentation allows for increased total electrode surface area within a compact volume, improving adhesion to external electrodes while maintaining small overall size.
Solution Approach 2:
The invention transitions from a single-layer structure to a multilayer stacked structure. By stacking multiple sheets with alternating anodes and cathodes, the effective electrode area is expanded in the thickness direction, enabling better adhesion and lower ESR without increasing the planar footprint of the capacitor.
2Volume of moving object
If the thickness of anodes and cathodes is reduced to enable smaller capacitor size, then the compactness is improved, but the equivalent series resistance (ESR) increases
Solution Approach 1:
The anodes and cathodes are divided into multiple segments within each sheet and across multiple sheets. This segmentation creates numerous contact points with external electrodes, reducing the overall ESR by providing multiple parallel current paths despite the reduced thickness of individual electrodes.
Solution Approach 2:
Multiple thin electrode sheets are combined in a stacked configuration, where the collective effect of many thin layers provides sufficient total conductivity and contact area to maintain low ESR, overcoming the limitation of reduced individual electrode thickness.
Data Source
AI summary
A solid electrolytic capacitor that includes a resin molding, a first external electrode, and a second external electrode. The resin molding includes a laminate of multiple capacitor elements, and a sealing resin sealing the laminate. The following are satisfied: t1<t2, t3<t4, t1<t3, and t4/t3<t2/t1, where t1 is the thickness of an inner portion of the cathode lead-out layer, the inner portion not being exposed at the second end surface; t2 is the thickness of an exposed portion of the cathode lead-out layer, the exposed portion being exposed at the second end surface; t3 is the thickness of an inner portion of the valve-action metal substrate, the inner portion not being exposed at the first end surface; and t4 is the thickness of an exposed portion of the valve-action metal substrate, the exposed portion being exposed at the first end surface.