Conductive Polymer Dispersion for Capacitor Corner Coverage
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Solution Overview
Problem
Solid electrolytic capacitors with conductive polymer cathodes face limitations in high voltage reliability due to poor dielectric-polymer interfaces and inadequate corner and edge coverage, leading to low breakdown voltage and reliability issues beyond 25V.
Innovation Solution
A method involving conductive polymer dispersions with varying weight ratios of polyanion to conductive polymer and the use of amine crosslinkers to enhance corner and edge coverage, improving Equivalent Series Resistance (ESR) performance without degrading humidity performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive polymer dispersions are used to form cathode coating, then the capacitor can be manufactured with standard process, but the corner and edge coverage is inadequate leading to poor high voltage reliability
Solution Approach 1:
The patent modifies the chemical composition parameters of the conductive polymer dispersion by incorporating specific additives and adjusting molecular weight distribution. This changes the rheological properties and surface affinity of the dispersion, enabling it to wet and adhere to corner and edge surfaces more effectively, thereby improving coverage without requiring changes to the manufacturing process
Solution Approach 2:
The patent introduces intermediary substances (additives) into the conductive polymer dispersion that act as mediators between the polymer and the substrate surface. These intermediaries improve interfacial adhesion and promote uniform distribution of the polymer material, ensuring complete coverage including difficult-to-reach corner and edge regions
2Reliability
If the dielectric-polymer interface quality is poor, then the manufacturing process is simpler, but the breakdown voltage is limited to about 55V
Solution Approach 1:
The patent changes the chemical and physical parameters of the polymer dispersion formulation to optimize interface formation. By adjusting molecular weight, functional group composition, and additive concentrations, the patent creates a dispersion that forms high-quality interfaces during standard processing, achieving breakdown voltages exceeding 55V without complicating the manufacturing process
Solution Approach 2:
The patent incorporates preliminary actions into the dispersion formulation itself, where pre-reacted components or pre-formed complexes in the dispersion prepare the interface structure in advance. This preliminary preparation ensures optimal interface quality upon deposition, enabling high breakdown voltage performance without requiring additional processing steps
3Reliability
If conductive polymer is applied by chemical or electrochemical oxidation polymerization, then the ESR is low, but the process complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the polymerization process into separate stages: first forming the conductive polymer coating through simple deposition, then performing controlled oxidation polymerization in subsequent steps. This segmentation allows the low-ESR polymerization to occur under optimized conditions while keeping the initial coating process simple and suitable for manufacturing
Solution Approach 2:
The patent performs preliminary actions by pre-forming the polymer coating structure and pre-positioning reactive groups before the actual oxidation polymerization. This preliminary preparation simplifies the subsequent polymerization step and makes the overall process more manufacturable while still achieving low ESR performance
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
The method achieves improved corner and edge coverage and ESR performance, enabling solid electrolytic capacitors to withstand higher voltages and enhance reliability by forming a defect-free conductive polymer coating that is robust against thermal mechanical stress.
Implementation Method 1
the use of amine crosslinkers to enhance corner and edge coverage, improving Equivalent Series Resistance (ESR) performance
Implementation Method 2
conductive polymer dispersions with varying weight ratios of polyanion to conductive polymer
Implementation Method 3
forming a defect-free conductive polymer coating
Data Source
AI summary
An improved process for forming an electrolytic capacitor is provided. The process comprises: providing an anode with an anode wire extending from the anode body; forming a dielectric on the anode to form an anodized anode; applying a first slurry wherein the first slurry comprises conducting polymer and polyanion, wherein the polyanion and conducting polymer are in a first weight ratio thereby forming a first slurry layer; and applying a second slurry on the first slurry layer wherein the second slurry comprises the conducting polymer and said polyanion and wherein the polyanion and the conducting polymer are in a second weight ratio wherein the second weight ratio is lower than the first weight ratio.