Solid Electrolytic Capacitor Lead Frame Alignment
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Solution Overview
Problem
Conventional solid electrolytic capacitors face challenges in accurately aligning capacitor elements during stacking, leading to low process yield and increased equivalent series resistance due to uneven stress distribution during welding, which results in cracks.
Innovation Solution
A lead frame design with projecting parts and slits on the anode parts of capacitor elements allows for precise alignment and simplified stacking, reducing equivalent series resistance by embedding the projecting parts into the anode parts and using plated layers for easy welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stacking method is used without alignment features, then the stacking process is simple, but the alignment precision of capacitor elements is poor
Solution Approach 1:
The lead frame's projecting part and the capacitor element's slit form a self-aligning mechanism where the slit automatically engages with the projecting part during stacking, eliminating the need for external alignment tools or complex positioning systems
Solution Approach 2:
The projecting part on the lead frame acts as an intermediary alignment feature that mediates between the stacking process and the capacitor element, providing a physical guide that ensures precise positioning without complicating the overall stacking procedure
2Productivity
If spot welding is applied to weld anode parts, then the welding process is efficient, but uneven stress distribution causes cracks
Solution Approach 1:
The anode part is designed with non-uniform thickness, creating local quality variations where the thickness is greater at certain areas. This distributes the welding stress locally to thicker regions, preventing crack formation while maintaining welding efficiency
Solution Approach 2:
The increased thickness at specific areas of the anode part serves as a pre-designed stress buffer that absorbs and distributes welding stress before it can concentrate and cause cracks, providing beforehand cushioning against potential failure
3Productivity
If capacitor elements are stacked without orientation features, then the stacking process is fast, but the process yield is low
Solution Approach 1:
The slit and projecting part combination creates a self-orienting system where the capacitor element automatically orients itself correctly during the stacking process, maintaining high stacking speed while ensuring precise orientation without requiring additional orientation steps
Data Source
AI summary
A solid electrolytic capacitor having multiple capacitor elements and a lead frame is provided. Each capacitor element includes an anode part, a cathode part, an insulating part and at least one first slit. The cathode part is disposed opposite to the anode part. The insulating part is disposed between the anode part and the cathode part. The first slit is disposed at the anode part. The lead frame has an upper surface and a lower surface where the capacitor elements are stacked on. The lead frame includes an anode terminal part electrically connected to the anode part, and includes a cathode terminal part electrically connected to the cathode part. Specially, the anode terminal part includes at least one first projecting part, which projects toward the upper surface. The capacitor elements are stacked on the upper surface and the first slit is inserted into the first projecting part.