Two-Layer Conductive Polymer Electrolytic Capacitor ESR Reduction
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Solution Overview
Problem
Existing electrolytic capacitors with conductive polymer layers face challenges in achieving high electrostatic capacity and low equivalent series resistance (ESR) due to insufficient coverage of the dielectric layer and inadequate conductivity, which is not effectively addressed by simply changing the viscosity of the solution as proposed in prior methods.
Innovation Solution
The use of a two-layer conductive polymer structure, where the first conductive polymer layer with a lower polymerization degree covers the dielectric layer, enhancing electrostatic polarization, and the second layer with a higher polymerization degree improves conductivity and adhesion, reducing ESR by optimizing the polymerization conditions and dopant usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single conductive polymer layer is formed, then the structure is simple, but the electrostatic capacity is insufficient and ESR cannot be effectively reduced
Solution Approach 1:
The conductive polymer layer is divided into two distinct layers: a first conductive polymer layer with lower polymerization degree (higher resistance) and a second conductive polymer layer with higher polymerization degree (lower resistance). This segmentation allows each layer to perform different functions - the first layer provides electrostatic polarization and prevents short circuits, while the second layer reduces ESR through high conductivity.
Solution Approach 2:
Different regions of the capacitor structure are assigned different material properties. The first layer uses conductive polymer with lower polymerization degree (higher resistance) suited for interfaces requiring polarization, while the second layer uses conductive polymer with higher polymerization degree (lower resistance) suited for bulk conductivity requirements. This local optimization of material properties resolves the contradiction between capacity and ESR.
2Reliability
If the conductive polymer layer has high conductivity, then ESR is reduced, but the risk of rapid reactions and short circuits increases
Solution Approach 1:
The first conductive polymer layer acts as an intermediary between the dielectric layer and the second conductive polymer layer. It provides a transition zone with moderate conductivity that prevents direct contact between high-conductivity material and the dielectric, thereby reducing the risk of rapid reactions and short circuits while still allowing the second layer to provide low ESR performance.
Solution Approach 2:
The polymerization degree of the conductive polymer is controlled to create two distinct conductivity levels. The first layer maintains higher resistance through lower polymerization degree, preventing short circuits, while the second layer achieves lower ESR through higher polymerization degree and better conductivity. This parameter differentiation resolves the contradiction between conductivity and safety.
3Reliability
If the conductive polymer layer provides high conductivity, then ESR is reduced, but the coverage and adhesion to the dielectric layer are insufficient
Solution Approach 1:
The first conductive polymer layer is formed first as a preliminary layer that ensures uniform coverage and good adhesion to the dielectric layer. This initial layer creates a stable foundation that improves subsequent coverage uniformity, allowing the second high-conductivity layer to be applied effectively without compromising adhesion or coverage quality.
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
This approach results in improved electrostatic capacity and reduced ESR, while also preventing rapid reactions and short circuits by maintaining higher resistance in the inner layer, thus enhancing the overall performance and reliability of the electrolytic capacitor.
Implementation Method 1
The first precursor is subjected to polymerization under a first atmosphere including oxygen when the first treatment liquid is prepared. The second precursor is subjected to polymerization under a second atmosphere that is different in oxygen concentration from the first atmosphere when the second treatment liquid is prepared.
Implementation Method 2
The first conductive polymer layer includes a first conductive polymer and a first polymer dopant having a sulfonate group. The second conductive polymer layer includes a second conductive polymer and a second polymer dopant having a sulfonate group.
Implementation Method 3
the first conductive polymer layer with a lower polymerization degree covers the dielectric layer, enhancing electrostatic polarization
Implementation Method 4
The second layer with a higher polymerization degree improves conductivity and adhesion, reducing ESR
Data Source
AI summary
An electrolytic capacitor includes an anode body having a dielectric layer, a first conductive polymer layer covering at least a part of the dielectric layer, and a second conductive polymer layer covering at least a part of the first conductive polymer layer. The first conductive polymer layer includes a first conductive polymer and a first polymer dopant having a sulfonate group. The second conductive polymer layer includes a second conductive polymer and a second polymer dopant having a sulfonate group. A polymerization degree of the first conductive polymer is lower than a polymerization degree of the second conductive polymer.