Solid Electrolytic Capacitor Polymer Slurry Blocking Layer
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Solution Overview
Problem
Solid electrolytic capacitors with conductive polymer cathodes face challenges in achieving defect-free polymer coatings on anodes, especially at edges and corners, leading to poor reliability and humidity performance due to surface energy effects and the use of crosslinkers, which degrade humidity performance.
Innovation Solution
A process involving a blocking layer of conductive polymer with a median particle size of at least 0.05 μm is applied to prevent crosslinker entry into anode pores, followed by controlled application of crosslinkers and polymer slurry layers to ensure uniform coverage and reduced residual ionic content, with subsequent washing to maintain polymer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If crosslinkers are added to improve polymer coverage on edges and corners, then coating coverage is improved, but humidity performance deteriorates
Solution Approach 1:
A blocking layer is introduced as an intermediary between the anode and the crosslinker-containing polymer slurry. This blocking layer prevents crosslinkers from entering and accumulating in the anode pores, thereby mediating between the need for good edge coverage (which requires crosslinkers) and the need for good humidity performance (which requires minimal crosslinker residue). The blocking layer allows controlled application of crosslinkers while protecting the anode interior.
Solution Approach 2:
The blocking layer is applied in advance before the main polymer slurry coating process. This preliminary action prepares the anode surface by creating a barrier that will control subsequent crosslinker absorption, ensuring that crosslinkers remain primarily on the surface where they are needed for edge coverage rather than being absorbed into the pores.
2Manufacturing precision
If polymer slurry is applied to achieve uniform coating, then coverage is improved, but cracks and delaminating occur due to thermal mechanical stress
Solution Approach 1:
The patent changes the particle size parameter of the polymer slurry to at least 0.05 μm (median particle size), which is a specific physical parameter modification. This parameter change allows the slurry to form a more uniform and adherent coating that better withstands thermal mechanical stress during anode resin encapsulation and surface-mounting, reducing cracks and delaminating.
3Ease of manufacture
If multiple coating-drying process steps are used, then polymer dispersion is simplified, but process complexity increases
Solution Approach 1:
The patent combines multiple coating and drying steps into an integrated process where polymer slurry is applied and dried in sequence with blocking layer formation. This merging of operations simplifies the overall manufacturing process by reducing the number of separate process steps while maintaining effective polymer dispersion and coating formation.
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 enhances polymer coverage on edges and corners, improving capacitor reliability and humidity performance by controlling crosslinker concentration and incorporating a blocking layer to prevent crosslinker absorption into anode pores, thereby reducing ESR and DC leakage.
Implementation Method 1
A process is provided that involves applying a blocking layer to anodes prior to application of polymer slurry thereby preventing absorption of crosslinkers into pores of the anodes
Implementation Method 2
applying a layer of conducting polymer slurry on the layer of crosslinker
Implementation Method 3
forming a layer of crosslinker on the blocking layer
Data Source
AI summary
A process for forming a solid electrolytic capacitor and an electrolytic capacitor formed by the process. The process includes: providing an anode wherein the anode comprises a porous body and an anode wire extending from the porous body; apply a thin polymer layer onto the dielectric, andforming a dielectric on the porous body to form an anodized anode;applying a first slurry to the anodized anode to form a blocking layer wherein the first slurry comprises a first conducting polymer with an median particle size of at least 0.05 μm forming a layer of crosslinker on the blocking layer; andapplying a layer of a second conducting polymer on the layer of crosslinker.