Electrolytic Capacitor End-Face Plating for Low ESR Reliability
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Solution Overview
Problem
Existing electrolytic capacitors face challenges in forming a uniform and thin electrolytic Ag plating layer, leading to increased ESR due to oxidation of the Ni plating layer exposure and pinhole generation, which also raises manufacturing costs.
Innovation Solution
The use of electroless Ni and Ag plating layers to cover the end faces of the anode and cathode parts, allowing for controlled thickness and adhesion improvement, reducing ESR and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an electrolytic Ag plating layer is formed to be thin and uniform, then manufacturing cost is reduced and ESR is lowered, but the Ni plating layer may be exposed or pinholes may generate leading to oxidation and reliability issues
Solution Approach 1:
The invention changes the plating method from electrolytic to electroless plating, which fundamentally alters the deposition mechanism. Electroless plating allows for better thickness control and uniformity without the complications of electrolytic plating, enabling thin yet reliable plating layers that prevent Ni exposure while maintaining low ESR
Solution Approach 2:
The invention uses a composite plating structure with multiple layers (electroless Ni plating layer and electroless Ag plating layer) where each layer serves a specific function. The electroless Ni layer provides a stable base with good adhesion, while the electroless Ag layer provides low contact resistance and oxidation resistance, creating a synergistic effect that resolves the contradiction between thinness and reliability
2Reliability
If the Ag plating layer thickness is increased to prevent Ni exposure and pinholes, then reliability is improved, but manufacturing cost increases due to excessive silver usage
Solution Approach 1:
By switching to electroless plating methodology, the invention achieves superior thickness control and uniformity, allowing the use of thinner Ag layers (可以有效控制厚度) that are sufficient to prevent Ni exposure and pinholes, thereby reducing silver consumption while maintaining reliability
Solution Approach 2:
The electroless plating process enables precise local control of plating thickness and quality, ensuring that the Ag layer is uniformly distributed and sufficiently thick only where needed to prevent Ni exposure, avoiding unnecessary silver usage in areas where it is not required
3Reliability
If electrolytic Ag plating is used to cover the end face, then electrical connection is established, but the plating layer cannot be formed uniformly and thinly leading to increased ESR
Solution Approach 1:
The invention replaces the electrolytic plating system with an electroless plating system, substituting a chemically-driven process for an electrically-driven one. This substitution eliminates the uniformity and thickness control issues inherent in electrolytic plating, allowing for precise control of Ag layer properties while maintaining electrical connection functionality
Solution Approach 2:
By changing the fundamental plating parameters from electrolytic to electroless methodology, the invention achieves superior control over plating thickness and uniformity, enabling the formation of thin, even Ag layers that provide good electrical connection without the defects of electrolytic plating
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 a highly reliable electrolytic capacitor with reduced ESR and improved electrical characteristics while minimizing silver usage and maintaining oxygen barrier properties.
Implementation Method 1
The end face exposed from the exterior body is covered with an electroless Ni plating layer
Implementation Method 2
The electroless Ni plating layer is covered with an electroless Ag plating layer
Data Source
AI summary
An electrolytic capacitor includes a capacitor element that includes an anode part and a cathode part, an exterior body that seals the capacitor element, a first external electrode that is electrically connected to the anode part, and a second external electrode that is electrically connected to the cathode part. At least one of an end face of the anode part or an end face of the cathode part is exposed from the exterior body to be electrically connected to a corresponding one of the first external electrode or the second external electrode. The end face exposed from the exterior body is covered with an electroless Ni plating layer, and the electroless Ni plating layer is covered with an electroless Ag plating layer. The electroless Ag plating layer is covered with the corresponding one of the first external electrode or the second external electrode.