Solid electrolytic capacitor and method for manufacturing the same

Abstract

A portion of an anode lead frame 3 of a solid electrolytic capacitor 1 is bent to form a protruding portion 4 that protrudes toward an anode lead 20. The protruding portion 4 includes a first horizontal portion 41 positioned higher than and substantially parallel to the anode lead 20, a second horizontal portion 40 contacting the anode lead 20, a sloping portion 42 linking the inner end of the first horizontal portion 41 with the outer end of the second horizontal portion 40, and an auxiliary bent portion 43 bent upward from the inner end of the second horizontal portion 40 and substantially symmetrical with the sloping portion 42. A contact surface 46 of the second horizontal portion 40 with the anode lead 20 is formed flat, and a surface 47 of the second horizontal portion 40 on the opposite side to the contact surface 46 is formed with a rounded curvature.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a solid electrolytic capacitor that includes a lead frame, and a method for manufacturing the same.[0003]2. Description of the Related Art[0004]Conventionally, a solid electrolytic capacitor (1) having the configuration shown in FIG. 8 is known (see Japanese Patent No. 3157722). The solid electrolytic capacitor (1) includes a capacitor element (2) with a thin wire-like anode lead (20) protruding therefrom. An anode lead frame (3) is resistance welded to the anode lead (20), and a cathode lead frame (30) is attached to the peripheral surface of the capacitor element (2) by a conductive adhesive (26). The capacitor element (2) and base ends of both lead frames (3) and (30) are covered with a synthetic resin housing (5), while portions of the lead frames (3) and (30) that protrude outside the housing (5) are bent downward along the peripheral surface of the housing (5), and then horizontall...

AI Technical Summary

Benefits of technology

[0022]1. A protruding portion (4) of an anode lead frame (3) is formed by bending a portion of the anode lead frame (3) into a first horizontal portion (41), a linking portion (specifically, sloping portion (42) in FIG. 2), a second horizontal portion (40), and an auxiliary bent portion (43). When forming the protruding portion (4) of the anode lead frame (3), the bending load acting on both sides of the protruding portion (4) is symmetrical and balanced, because processing is preformed using a center impeller structure for pressing symmetrically with both ends of the protruding portion (4) held down. Any displacement due to springback of the anode lead frame (3) is thereby symmetrical, allowing the protruding portion (4) to be kept horizontal. Also, since the pressing load of the welding electrode is supported on both sides of the protruding portion (4) when welding the anode lead (20) to the second horizontal portion (40), the parallelism of the anode lead (20) and the second horizontal portion (40) is not disturbed during welding.

[0023]Consequently, the capacitor element (2) is correctly attached to the anode lead frame (3), increasing the substantial contact area between the anode lead (20) and the anode lead frame (3). Problems such as weak bonding strength and increased ESR resulting from incorrect attachment of the capacitor element (2) as in the prior art can thereby be resolved.

[0024]2. Also, because a contact surface (46) of the second horizontal portion (40) with the anode lead (20) is formed flat, the contact area between the contact surface (46) and the anode lead (20) is enlarged. In this respect also, the bonding strength between the anode lead (20) and the anode lead frame (3) can be enhanced, and ESR reduced. Further, because a surface (47) of the second horizontal portion (40) on the opposite side to the contact surface (46), that is, the underside of the second horizontal portion (40) is rounded for reinforcement, cracking or the like when the contact surface (46) of the second horizontal portion (40) with the anode lead (20) is pressed flat can be prevented.

[0025]3. Also, because the contact surface (46) of the second horizontal portion (40) with the anode lead (20) undergoes a pressing process for flattening out the protruding portion (4) using a die to make the protruding portion (4) thinner, the distance from the first horizontal portion (41) to the auxiliary bent portion (43) via the sloping portion (42) and the second horizontal portion (40) is lengthened in comparison to when a pressing process to flatten out the contact surface (46) is not performed. That is, because the contact surface (46) is formed by flattening out the protruding portion (4) to make it thinner, an equivalent amount of the material is protruded, elongating the sloping portion (42) and the auxiliary bent portion (43), and increasing the overall length of the protruding portion (4).

[0026]A vertical distance H between the first horizontal portion (41) and the second horizontal portion (40) can thereby be lengthened without changing the initial cutoff length of the anode lead frame (3), making it possible to also accommodate cases where the peripheral surface height or outer diameter of the capacitor element (2) is large. Being able to accommodate increases in the size of the capacitor element (2) enables the capacity of the solid electrolytic capacitor (1) to be increased.

Problems solved by technology

This results in problems such as weak bonding strength and increased ESR (Equivalent Series Resistance).

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