Electrolytic Capacitor Radial Lead Shift for ESL Reduction
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Solution Overview
Problem
Conventional electrolytic capacitors with a multi-terminal structure face challenges in maintaining stable connections of lead tab terminals to the foils, especially in high-frequency applications, due to increased equivalent series inductance (ESL) and equivalent series resistance (ESR), which are exacerbated by the smaller size of electronic devices, leading to variations in pitch between leads and poor connection stability.
Innovation Solution
The use of band-shaped anode and cathode foils with a plurality of lead tab terminals, where the lead tab terminals are arranged with a radial shift, allowing for a longer distance between connection portions, enabling stable connection and maintaining desired pitch without increasing the pitch between leads, thereby reducing ESL and ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch between lead tab terminals is reduced to maintain stable connection, then connection stability is improved, but equivalent series inductance (ESL) increases
Solution Approach 1:
The patent applies dimensional transformation by shifting the lead tab terminals from a planar arrangement to a three-dimensional configuration where leads are positioned at different radial distances from the winding center. This spatial reorganization allows the connection portions to be close together (improving connection stability) while the leads extend to different radial positions (maintaining acceptable ESL), effectively resolving the contradiction through dimensional change.
Solution Approach 2:
The patent employs asymmetric arrangement of lead tab terminals where the leads are positioned at different radial distances from the winding center of the capacitor element. This asymmetric configuration allows optimization of both connection stability and ESL by creating unequal lead lengths and positions, breaking the symmetry that would otherwise force a trade-off between these two parameters.
2Productivity
If the capacitor size is reduced, then productivity and device integration are improved, but connection stability of lead tab terminals deteriorates
Solution Approach 1:
The patent applies the nesting principle by positioning the connection portions of lead tab terminals within the inner radial region of the capacitor element, nested close to the winding center. This allows the leads to be accommodated in a compact space while maintaining stable electrical connection to the foils, enabling miniaturization without sacrificing connection reliability.
Solution Approach 2:
The patent resolves the size-stability contradiction by transitioning to a three-dimensional lead arrangement where connection portions are positioned at different radial distances. This dimensional approach allows compact capacitor design while maintaining adequate connection stability through optimized spatial configuration of the leads relative to the winding structure.
3Object-affected harmful factors
If the pitch between leads is increased to reduce ESL, then equivalent series inductance (ESL) is reduced, but the distance between connection portions must be increased, complicating manufacturing
Solution Approach 1:
The patent applies preliminary action by pre-positioning the connection portions of lead tab terminals at optimized locations on the foils before winding. This advance configuration ensures that after winding, the connection portions are at appropriate radial distances for stable connection, while leads extend to positions that achieve low ESL, all without requiring complex post-manufacturing adjustments.
Solution Approach 2:
The patent resolves the manufacturing complexity issue by using dimensional transformation to achieve low ESL through radial positioning rather than increasing circumferential pitch. This allows connection portions to remain close together (simplifying manufacturing) while leads are positioned at different radial distances (reducing ESL), eliminating the need to increase pitch and thereby reducing manufacturing complexity.
Data Source
AI summary
A one-side pressed terminal is applied as a first anode (cathode) lead tab terminal and the one-side pressed terminal is connected to an anode (a cathode) foil in such a manner that a position in a radial direction of a lead is shifted inward after winding. A one-side pressed terminal is applied as a second anode (cathode) lead tab terminal and the one-side pressed terminal is connected to the anode (cathode) foil in such a manner that a position in the radial direction of a lead is shifted inward after winding. Thus, while retaining characteristics as an electrolytic capacitor, connection of the anode (cathode) lead tab terminal to the anode (cathode) foil can be achieved in a stable manner.