Solid Electrolytic Capacitor End Surface Plating
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Solution Overview
Problem
Solid electrolytic capacitors face challenges in reducing Equivalent Series Resistance (ESR) and Equivalent Series Inductance (ESL) while maintaining a compact size and reliability, with issues related to external electrode peeling due to poor adhesion at resin boundaries.
Innovation Solution
The design incorporates a solid electrolytic capacitor with a metal layer having recesses, a dielectric layer, and a cathode portion with a solid electrolyte and current collector layer, buried within an insulating resin body. The external electrodes are plated with specific layers and connected to the metal and conductor layers, with conductive particles and an insulating resin layer to enhance adhesion and reduce ESR and ESL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external electrodes are formed to extend from end surface to main surface without processing end surface of cut resin mold, then manufacturing process is simplified, but external electrode poorly adheres and tends to peel off at boundary between end surface and main surface of resin
Solution Approach 1:
The end surface of the resin mold is processed (cut or ground) before forming the external electrode, creating a flat surface that ensures good adhesion. This preliminary surface preparation prevents subsequent peeling of the external electrode at the boundary between end surface and main surface.
2Volume of moving object
If solid electrolytic capacitor size is reduced for miniaturization, then compactness is improved, but ESR and ESL reduction becomes more difficult
Solution Approach 1:
The invention reduces ESR and ESL by optimizing the three-dimensional arrangement of internal components. The anode terminal and cathode terminal are positioned at opposite ends of the stack, and the leading conductor layer is configured to minimize current path length, achieving low ESR and ESL in a compact volume through spatial optimization.
Solution Approach 2:
Multiple capacitor elements are stacked and integrated within a compact resin body, with terminals and conductors nested efficiently within the limited space. This nested arrangement maintains electrical performance while achieving miniaturization.
3Ease of operation
If anode terminal and cathode terminal are drawn out from center of stack to outside of resin, then terminal accessibility is improved, but capacitor size increases
Solution Approach 1:
The terminals are extracted from the center of the stack and positioned at the end surfaces of the resin body. This extraction allows easy accessibility for electrical connection while keeping the capacitor compact, as the terminals are integrated into the end surfaces rather than extending outward.
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 configuration results in a compact solid electrolytic capacitor with reduced ESR and ESL, improved reliability, and suppressed peeling of external electrodes, maintaining electrostatic capacity and reliability while allowing for miniaturization.
Implementation Method 1
The first external electrode has at least one plating layer on the first end surface, and is connected to the leading conductor layer at the first end surface. The second external electrode has at least one plating layer provided on the second end surface, and is connected to the metal layer at the second end surface.
Implementation Method 2
a plurality of conductive particles are present in each of the first end surface and the second end surface
Implementation Method 3
a dielectric layer provided on the external surface of the metal layer
Implementation Method 4
a cathode portion having a solid electrolyte layer provided on the dielectric layer
Data Source
AI summary
A solid electrolytic capacitor that includes a capacitor element including an anode portion having a metal layer, a dielectric layer, and a cathode portion having a solid electrolyte layer and a current collector layer; a leading conductor layer; an insulating resin body covering the capacitor element and the leading conductor layer, the insulating resin body having a first end surface and a second end surface opposite to each other; a first external electrode; and a second external electrode. The first external electrode has at least one plating layer on the first end surface, and is connected to the leading conductor layer at the first end surface. The second external electrode has at least one plating layer on the second end surface, and is connected to the metal layer at the second end surface.