Solid Electrolytic Capacitor Edge Rounding for Stable ESR
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Solution Overview
Problem
In solid electrolytic capacitors, the insufficient thickness of conductive paste layers at the peripheral edges of the exterior body can lead to peeling of the external electrodes, allowing air to intrude and deteriorate the equivalent series resistance (ESR) characteristics.
Innovation Solution
The solution involves rounding the peripheral edges of the end surfaces of the exterior body to ensure a sufficient thickness of the conductive paste layers, thereby preventing peeling and maintaining the integrity of the ESR characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the peripheral edges of the end surfaces are left sharp, then the exterior body can be manufactured with simpler processes, but the conductive paste layer thickness becomes insufficient causing peeling and ESR deterioration
Solution Approach 1:
The peripheral edges of the end surfaces are rounded instead of being sharp, creating a curved transition zone that allows the conductive paste layer to maintain sufficient thickness. This curvature prevents the paste layer from becoming too thin at the edges while avoiding the need for complex manufacturing processes, as rounding can be achieved through standard finishing operations.
2Reliability
If the conductive paste layer is made thicker at peripheral edges, then peeling and air intrusion are prevented, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The peripheral edges are rounded in advance, before the conductive paste layer is applied. This preliminary geometric modification creates a favorable substrate shape that ensures uniform and sufficient paste layer thickness during the subsequent coating process, eliminating the need for complex control mechanisms during paste application and simplifying the overall manufacturing process.
Data Source
AI summary
A solid electrolytic capacitor includes at least one capacitor element including an anode part and a cathode part, an exterior body that has a first end surface at which the anode part is exposed and a second end surface at which the cathode part is exposed, a first external electrode that covers the first end surface, and a second external electrode that covers the second end surface. The exterior body seals the at least one capacitor element. The first external electrode includes a first conductive paste layer and is electrically connected to the anode part. The second external electrode includes a second conductive paste layer and is electrically connected to the cathode part. Each of the peripheral edge of the first end surface and the peripheral edge of the second end surface is rounded.