Porous Anode Structure in Electrolytic Capacitors for Lower ESR
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Solution Overview
Problem
Existing electrolytic capacitors face challenges in reducing equivalent series resistance (ESR), leakage current (LC), and capacity degradation rate, with room for improvement in performance.
Innovation Solution
The electrolytic capacitor design includes a porous anode body with controlled Log differential pore size distribution, featuring a first and second peak pore diameter ratio of 2.7 or more, and a conductive polymer coverage of 10% or more in an intermediate region, optimizing voids for enhanced conductive path formation and polymer packing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anode body uses a uniform pore size structure, then the manufacturing process is simple, but the conductive polymer packing efficiency and ESR reduction are insufficient
Solution Approach 1:
The anode body is designed with a specific porous structure characterized by a Log differential pore size distribution with a peak at 0.8-2.0 μm. This controlled porosity enables efficient conductive polymer packing while maintaining manufacturing feasibility through sintering of metal particles.
Solution Approach 2:
The invention controls the pore size distribution parameters, specifically setting the peak pore diameter at 0.8-2.0 μm and maintaining porosity at 30-60%. These parameter optimizations balance the competing requirements of ESR reduction and manufacturing complexity.
2Reliability
If the conductive polymer coverage is increased to reduce leakage current, then the leakage current decreases, but the manufacturing complexity and material cost increase
Solution Approach 1:
The porous anode body structure with optimized pore size distribution enables the conductive polymer to effectively fill and cover the pore surfaces. This structure allows achieving low leakage current with moderate polymer coverage, balancing performance and manufacturing complexity.
3Reliability
If the anode body porosity is increased to improve capacity, then the electrostatic capacity increases, but the structural strength decreases
Solution Approach 1:
The anode body utilizes a controlled porous structure with porosity optimized at 30-60% and specific pore size distribution (peak at 0.8-2.0 μm). This configuration maximizes electrostatic capacity while maintaining adequate structural strength through the sintered metal particle framework.
Solution Approach 2:
The anode body is constructed as a composite of sintered metal particles forming a porous framework. This composite structure provides both the high surface area needed for capacity and the mechanical strength required for structural integrity.
Data Source
AI summary
An electrolytic capacitor includes a capacitor element including: a porous anode body having a dielectric layer; an anode wire; and a conductive polymer. In a Log differential pore size distribution, based on volume, of voids in the anode body having the dielectric layer, a first peak for a first pore diameter D1 and a second peak for a second pore diameter D2 (D1<D2) are observed. D2/D1 is 2.7 or more. A ratio (Rpm) of the area of the conductive polymer in an intermediate region to the area of the intermediate region is 10% or more. The distribution is measured for an element cross section of the capacitor element that intersects the anode wire. The intermediate region includes, in the element cross section, a midpoint between a center of the anode wire and a point on an outer surface of the capacitor element, located farthest from the center.