JP2007096021A - Chip type solid electrolytic capacitor and lead frame therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-type solid electrolytic capacitor of a lower surface electrode type which has high junction strength between a terminal and an armor resin, and prevents generation of defective appearance. <P>SOLUTION: In the chip-type solid electrolytic capacitor, at least one surface of an anode terminal 13 and a cathode terminal 12 is formed to be exposed from a packaging resin 16, and an enlarged surface 15 is formed so that a contact area increases in a contact interface to the packaging resin 16 near the tip of the anode terminal 13 and the cathode terminal 12. The mounting surface side of the enlarged surface 15 is provided with a slope 14 so that a board thickness thereof becomes thinner as it gets close to a terminal tip. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip-type solid electrolytic capacitor and a lead frame used therefor, and more particularly to a bottom-electrode type chip-type solid electrolytic capacitor and a lead frame used for manufacturing the same.

  A conventional bottom electrode chip type solid electrolytic capacitor will be described with reference to the drawings. 4 shows a chip-type solid electrolytic capacitor of Conventional Example 1, FIG. 4 (a) is a front sectional view, and FIG. 4 (b) is a bottom view. In FIG. 4B, the difference in material is indicated by a pattern attached to each part. 11 is a capacitor element, 41 is an anode lead wire, 12 is a cathode terminal, 13 is an anode terminal, 16 is an exterior resin, 42 and 43 are fillet forming surfaces, and 44 is a conductive adhesive. As a similar chip-type solid electrolytic capacitor, for example, there is a technique of Patent Document 1.

  5A and 5B show a chip-type solid electrolytic capacitor according to Conventional Example 2. FIG. 5A is a front sectional view and FIG. 5B is a bottom view. In FIG. 5B, the difference in material is displayed by a pattern attached to each part, and a part of the exterior resin is removed. The reference numerals of the respective parts are the same as those in FIG. The conventional example 2 is similar to the conventional example 1 except for the cathode terminal 12 and the anode terminal 13. In this conventional example 2, the terminal tip portions of the cathode terminal 12 and the anode terminal 13 are extended inside the exterior resin while keeping the dimension of the exposed portion of the mounting surface of the terminal at a predetermined value according to the standards such as JIS and MIL. As a result, an enlarged surface portion (enlarged portion) 15 is formed at the tip of the terminal. That is, the enlarged surface portion 15 for increasing the bonding strength with the exterior resin is formed by enlarging the surface area at the interface with the exterior resin near the tip of the terminal and the anchor effect due to the unevenness. As a similar chip-type solid electrolytic capacitor, for example, there is a technique of Patent Document 2.

JP 2002-175940 A JP 2002-367862 A

  In the chip-type solid electrolytic capacitor of Conventional Example 1 described with reference to FIG. 4, the bonding strength between the terminal and the exterior resin is weak, and the terminal may drop off. On the other hand, in the chip-type solid electrolytic capacitor of Conventional Example 2 described with reference to FIG. 5, the exterior resin may not be completely filled between the terminal enlarged surface portion and the mounting surface. This is because the terminal thickness is made as thin as possible in order to increase the volume efficiency (the ratio of the capacitor element volume to the total product volume), and if the terminal tip is processed as shown in FIG. Since the space between the surface portion and the mounting surface is narrow, it is difficult for the exterior resin to enter. In particular, in the vicinity of the boundary between the mounting surface side exposed portion and the expanded surface portion of the terminal, the resin is not easily filled. This will be described with reference to the drawings.

  FIG. 6 shows the state of molding by the exterior resin in the vicinity of the terminal mounting surface exposed portion in the chip-type solid electrolytic capacitor of Conventional Example 2, FIG. 6 (a) is a sectional view near the cathode terminal, and FIG. It is a bottom view near the cathode terminal. In the molding process using the exterior resin, as illustrated in FIG. 6A, the exterior resin enters the enlarged surface portion (near the tip) of the cathode terminal 12 like the path 20, but an unfilled portion 17 may occur. . When viewed from the bottom side, the unfilled portion 17 is formed as shown in FIG. 6B, and the unfilled portion 17 becomes an obstacle when the product is mounted on the substrate, and the terminal bonding strength with the exterior resin. Bring about a decline.

  In this situation, an object of the present invention is to provide a bottom electrode type chip-type solid electrolytic capacitor having a high bonding strength between a terminal and an exterior resin and capable of preventing appearance defects, and a lead frame used therefor. is there.

  In order to solve the above problems, the chip-type solid electrolytic capacitor of the present invention is formed so that at least one surface of the anode terminal and the cathode terminal is exposed from the exterior resin, and the exterior in the vicinity of the tip of the anode terminal and the cathode terminal In a chip-type solid electrolytic capacitor that has been enlarged in the vicinity of the tip so as to increase the contact area at the contact interface with the resin, the mounting surface side of the portion that has been enlarged is closer to the tip of the terminal As a result, an inclined surface is provided so that the plate thickness becomes thinner.

  The lead frame of the present invention is formed so that at least one surface of the anode terminal and the cathode terminal is exposed from the exterior resin, and the contact area is at the contact interface with the exterior resin in the vicinity of the tip of the anode terminal and the cathode terminal. In a lead frame used for a chip-type solid electrolytic capacitor whose surface has been enlarged in the vicinity of the tip so as to increase, the mounting surface of the anode terminal and cathode terminal forming portion is formed such that the plate thickness decreases as the tip is approached. An inclined surface is provided on the side.

  In the lead frame of the present invention, since the mounting surface side is inclined so that the thickness decreases toward the tip of the terminal forming portion, when the chip type solid electrolytic capacitor is manufactured using the lead frame of the present invention, the exterior In the resin molding process, the exterior resin can surely enter the boundary with the exposed portion of the board mounting surface, and as a result, the bonding strength between the terminal and the exterior resin is high, and the appearance of the appearance electrode can be prevented. A chip-type solid electrolytic capacitor of the type can be manufactured, and the chip-type solid electrolytic capacitor can be provided.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a chip-type solid electrolytic capacitor according to an embodiment of the present invention. FIG. 1 (a) is a front sectional view and FIG. 1 (b) is a bottom view. The reference numerals are common to other figures. An anode lead wire 41 is led out from the capacitor element 11, and a bottom electrode type anode terminal 13 is connected to the cathode layer of the capacitor element 11, and a bottom electrode type cathode terminal 12 is connected to the cathode layer of the capacitor element 11 by a conductive adhesive 44. . A fillet forming surface 43 is formed on the side surface portion of the anode terminal 13, an enlarged surface portion (enlarged portion) 15 is formed in the vicinity of the tip on the opposite side, and the inclined surface 14 is formed on the substrate mounting surface side. Yes. Further, a fillet forming surface 42 is provided on the product side surface portion of the cathode terminal 12, an enlarged surface portion 15 is formed in the vicinity of the tip portion on the opposite side, and the inclined surface 14 is formed on the substrate mounting surface side. When this shape is viewed from the bottom surface (mounting surface) side, it is as shown in FIG.

  The terminal forming portion of the lead frame used in this embodiment is shown in FIGS. FIG. 2 is a perspective view from above schematically showing the terminal forming portion of the lead frame in one embodiment of the present invention, and FIG. 3 is a perspective view from below schematically showing the terminal forming portion of the lead frame. FIG. 2 and 3, the enlarged surface portions 15 are formed on both upper and lower sides in the vicinity of the tip of the terminal. Further, an inclined surface 14 is formed on the lower side so that the thickness decreases as it approaches the tip of the terminal. At this time, the surface enlargement method is based on a known technique. For example, pressing, coining, sand blasting, etching, laser trimming, drilling, and the like can be performed. The surface area was increased by providing six recesses per area of 1 mm × length 0.5 mm. Further, the surface enlargement was performed simultaneously with the formation of the inclined surface 14.

Since the capacitor element is manufactured by a known technique, the description is simplified. Taking tantalum as a valve metal, for example, tantalum powder is molded around a tantalum wire and sintered at high vacuum and high temperature. Next, an oxide film of Ta ₂ O ₅ is formed on the surface of the tantalum metal powder. Further, after being immersed in manganese nitrate, it is thermally decomposed to form MnO ₂ , and subsequently a cathode layer made of graphite and Ag is formed to obtain a capacitor element. If a conductive polymer such as polythiophene or polypyrrole is used instead of MnO ₂ in the cathode layer, a further lower ESR (equivalent series resistance) can be obtained. In addition to tantalum, niobium, aluminum, titanium, or the like can be used as the valve metal.

  Also in the production of a chip-type solid electrolytic capacitor using the capacitor element, the anode terminal forming portion of the lead frame and the anode lead wire of the capacitor element are connected by resistance welding or laser welding, and the cathode layer of the capacitor element and the lead frame are connected. The connection with the cathode terminal forming portion can be made with a conductive adhesive. The molding process of the exterior resin can also be performed without changing the known technique.

  As described above, an inclined surface is provided on the mounting surface side of the terminal tip portion, and the terminal tip portion is formed so as to become thinner as approaching the tip. As a result, it was possible to prevent the appearance defect of the exterior and the defect in the reflow soldering process when mounting the board.

  The lead frame of the present invention can be used not only for a lower surface electrode type chip-type solid electrolytic capacitor but also for a general lower surface electrode type electronic component.

BRIEF DESCRIPTION OF THE DRAWINGS The chip-type solid electrolytic capacitor in one embodiment of this invention is shown, Fig.1 (a) is the front sectional drawing, FIG.1 (b) is a bottom view. The perspective view from the upper side which shows typically the terminal formation part of the lead frame in one embodiment of this invention. The perspective view from the lower part which shows typically the terminal formation part of the lead frame in one embodiment of this invention. The chip type solid electrolytic capacitor of the prior art example 1 is shown, Fig.4 (a) is a front sectional view, FIG.4 (b) is a bottom view. The chip-type solid electrolytic capacitor of the prior art example 2 is shown, Fig.5 (a) is a front sectional view, FIG.5 (b) is a bottom view. FIG. 6 (a) is a cross-sectional view of the vicinity of the cathode terminal, and FIG. 6 (b) is the vicinity of the cathode terminal. Bottom view.

Explanation of symbols

11 Capacitor element 12 Cathode terminal 13 Anode terminal 14 Inclined surface
15 Expanded surface portion 16 Exterior resin 20 Path 41 Anode lead wires 42 and 43 Fillet forming surface 44 Conductive adhesive

Claims (2)

  At least one surface of the anode terminal and the cathode terminal is formed so as to be exposed from the exterior resin, and is expanded near the tip so that the contact area increases at the contact interface with the exterior resin near the tip of the anode terminal and the cathode terminal. In the chip-type solid electrolytic capacitor subjected to surfaceization, an inclined surface is provided on the mounting surface side of the surface-enlarged portion so that the plate thickness becomes thinner as approaching the terminal tip. Chip-type solid electrolytic capacitor.   At least one surface of the anode terminal and the cathode terminal is formed so as to be exposed from the exterior resin, and is expanded near the tip so that the contact area increases at the contact interface with the exterior resin near the tip of the anode terminal and the cathode terminal. In the lead frame used for the chip-type solid electrolytic capacitor with surface treatment, the anode terminal and cathode terminal forming portion is provided with an inclined surface on the mounting surface side so that the plate thickness becomes thinner toward the tip. Lead frame characterized by.

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