JP5073012B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor in which a plurality of capacitor elements are arranged in parallel, and a method for manufacturing the same.

  Conventionally, a chip-type solid electrolytic capacitor shown in FIG. 9 is known (see, for example, Patent Document 1).

  The solid electrolytic capacitor (1) includes a capacitor element (2) having a lead frame (9), (90) attached to its lower surface, and the capacitor element (2) is covered with a synthetic resin housing (70). As shown in FIG. 10, the capacitor element (2) has a dielectric oxide film (21) formed on an anode body (20) which is a valve metal foil, and a part of the dielectric oxide film (21). In addition, a cathode layer (3), a carbon layer (6), and a silver paste layer (60) are provided in this order, and a plurality of these layers are stacked. That is, the part where the cathode layer (3) is formed on the anode body (20) becomes the cathode part (2b), and the remaining part becomes the anode part (2a). A plurality of anode bodies (20) and (20) are stacked, the anode portion (2a) is bonded to the anode-side lead frame (9) by resistance welding, and the cathode portion (2b) is bonded to the cathode-side lead frame (90 by conductive adhesive). ). This increases the capacitance.

  The manufacturing method of a capacitor | condenser element (2) is shown. First, a sheet of aluminum foil is cut out to form a strip-shaped anode body (20), and a part of the anode body (20) is immersed in a 0.01 to 0.02 wt% phosphoric acid aqueous solution or adipic acid aqueous solution to perform electrolytic oxidation. The dielectric oxide film (21) is formed by processing. Next, the formation part of the dielectric oxide film (21) of the anode body (20) is immersed in a solution of 3,4-ethylenedioxythiophene and ferric P-toluenesulfonate using butanol as a solvent, and polythiophene A cathode layer (3) made of a conductive polymer is formed. On this cathode layer (3), a carbon layer (6) and a silver paste layer (60) are formed in this order. A plurality of anode bodies (20) and (20) are stacked and the anode portions (2a) and (2a) are welded to complete the capacitor element (2).

  The material for forming the cathode layer (3) includes, in addition to the polythiophene, a conductive polymer such as polypyrrole, polyaniline, polyfuran, TCNQ (7, 7, 8, 8-tetracyanoquinodimethane) complex salt, etc. Is mentioned. By using a conductive polymer having a low resistance value or the like for the cathode layer (3), the ESR is reduced and a capacitor having excellent high frequency characteristics is formed.

International Publication No. WO00 / 74091

  In recent years, such a capacitor is often used in a high-frequency region, and it is required to lower not only ESR (equivalent series resistance) but also ESL (equivalent series inductance) as a characteristic of the capacitor. In the structure shown in FIG. 9, since the space | interval of the anode side and cathode side lead frames (9) and (90) is vacant, ESL becomes large. In addition, if the number of stacked anode bodies (20) and (20) is increased for the purpose of increasing electrostatic capacity and reducing ESR, it may not be possible to meet market demands for lowering capacitors. There is also.

  In order to solve this point, as shown in FIG. 11, it is conceivable to connect the capacitors (1) and (1) in parallel by a pattern (40) on the substrate (4) on which the capacitors are mounted. FIG. 12 is an equivalent circuit diagram of FIG. For example, when the capacity of the capacitor (1) is C1 and the ESL is L1, the combined capacity when the two capacitors (1) and (1) are connected in parallel is 2 × C1, and the combined ESL is L1 / 2. . Thereby, when obtaining the same electrostatic capacity as before, it is considered that the number of anode bodies (20) and (20) to be laminated can be reduced and the ESL can be reduced.

  However, since the lead frames (9) and (90) of each capacitor (1) are individually mounted on the substrate (4), the contact resistance between the substrate (4) and the lead frames (9) and (90) increases. In fact, ESL also increases. Further, since a gap (P in FIG. 11) is formed between adjacent capacitors (1) (1), an extra mounting space is required.

  An object of the present invention is to reduce the ESL while reducing the capacitor, and to eliminate an extra mounting space.

The present invention relates to a flat capacitor element having an anode part and a cathode part, an anode side lead frame connected to the anode part, a cathode side lead frame connected to the cathode part, a capacitor element, and an anode side lead frame And a housing that covers the cathode side lead frame, and a solid electrolytic capacitor in which a part of the anode side lead frame and a part of the cathode side lead frame are exposed from the lower surface of the housing. The first portion having a surface exposed from the lower surface of the first portion and the second portion having a thickness thinner than the first portion and the lower surface side covered with the housing, and the anode portion is joined to the upper surface of the second portion by resistance welding the lower surface of the second portion has a resistance welding traces formed by resistance welding, resistance welding marks are to be covered by the housing A solid electrolytic capacitor according to symptoms.

  With the above configuration, the resistance welding trace with the anode portion in the anode side lead frame can be hidden by the housing.

It is sectional drawing of a solid electrolytic capacitor. It is sectional drawing of another solid electrolytic capacitor. It is sectional drawing of another solid electrolytic capacitor. It is sectional drawing of another solid electrolytic capacitor. It is a graph which compares and shows the impedance characteristic of the solid electrolytic capacitor of this example, and the conventional solid electrolytic capacitor. It is a perspective view of another solid electrolytic capacitor. It is a top view which shows the manufacturing process of the solid electrolytic capacitor shown in FIG. It is a top view which shows the manufacturing process of the solid electrolytic capacitor shown in FIG. It is sectional drawing of the conventional solid electrolytic capacitor. It is sectional drawing of the anode body which comprises a capacitor | condenser element. It is the top view which has arrange | positioned the capacitor | condenser in parallel on the board | substrate. FIG. 12 is an equivalent circuit diagram of FIG. 11. First Example An example of the present invention will be described in detail below with reference to the drawings.

  FIG. 1 is a cross-sectional view of the solid electrolytic capacitor (1). The solid electrolytic capacitor (1) includes a capacitor element (2) in which a plurality of anode bodies (20) and (20) are stacked and the anode portions (2a) are welded to each other. The cathode part (2b) is the same as the conventional one in that the cathode layer (3), the carbon layer (6), and the silver paste layer (60) are provided in this order on the dielectric oxide film (21). . The capacitor element (2) is covered with a synthetic resin housing (70), and the anode side lead frame (9) and the cathode side lead frames (90) (90) are exposed from the lower surface of the housing (70). .

  As shown in FIG. 1, two capacitor elements (2) and (2) are provided along the arrangement direction of the lead frames (9) and (90), that is, along the lateral direction, and the anode parts (2a) and (2a) of each other. Are facing inward. On the lower surface of the housing (70), an anode side lead frame (9) is provided at the center portion along the arrangement direction of the lead frames (9) and (90), and the anode side lead frame (9) is sandwiched between 2 Two cathode side lead frames (90) (90) are provided. The anode side lead frame (9) and each cathode side lead frame (90) are positioned with the opening (92) in between.

  The anode portions (2a) and (2a) of both capacitor elements (2) and (2) are attached to a common anode side lead frame (9) by resistance welding. That is, the capacitor elements (2) and (2) are connected in parallel. The cathode portions (2b) and (2b) facing opposite to each other are attached to the respective cathode side lead frames (9) and (90) by a conductive adhesive. Concave surfaces (91) and (91) are formed in the lead frames (9) and (90). The concave surfaces (91) and (91) are filled with a resin constituting the housing (70), so that the anode side lead frame ( The resistance welding trace of 9) is hidden. Further, moisture enters from the boundary between the concave surfaces (91) and (91) and the lead frames (9) and (90) to prevent the capacitor element (2) from reaching.

  In this example, the anode portions (2a) and (2a) of the capacitor elements (2) facing each other are attached to one anode side lead frame (9) and arranged in parallel, so that each capacitor element (2) ( 2) The length of the wiring (S in FIG. 12) that connects them can be shortened. Thereby, ESL can be reduced.

  Conventionally, in order to increase the capacitance and reduce the ESR, the number of anode bodies (20) and (20) to be laminated has been increased. However, in this example, a plurality of capacitor elements (2) and (2) are arranged in parallel with the anode portions (2a) and (2a) facing each other and attached to a common anode-side lead frame (9). In the case of obtaining electric capacity, the number of anode bodies (20) and (20) to be laminated can be reduced, and the capacitor can be lowered.

  Since the anode side lead frame (9) and the two cathode side lead frames (90) (90) are provided, the capacitor element (2) having a different number of laminated anode bodies (20) is connected to the anode part (2a). When the anode side lead frame (9) and 1: one cathode side lead frame (90) are connected by arranging (2a) facing each other in parallel, 2: the other cathode side lead frame (90 3): When both cathode side lead frames (90) (90) are connected, three different types of capacitance can be taken out, and the number of capacitors placed on the circuit board, etc. Can be reduced.

  FIG. 5 is a graph showing a comparison of impedance characteristics of the solid electrolytic capacitor (1) of this example and the conventional solid electrolytic capacitor (1) shown in FIG. The vertical axis of the graph represents impedance (unit: Ω), and the horizontal axis represents frequency (unit: kHz). As can be seen from FIG. 5, as compared with the conventional solid electrolytic capacitor (1), the solid electrolytic capacitor (1) of FIG. 1 has reduced ESL at a frequency higher than the resonance point. This is to shorten the wiring length connecting each capacitor element (2) (2) by attaching the anode part (2a) (2a) of the capacitor element (2) to the common anode side lead frame (9). As a result, ESL could be reduced.

  As shown in FIG. 2, the anode portions (2a) of the capacitor elements (2) facing each other may be overlapped and welded. Further, as shown in FIG. 3, the capacitor elements (2) and (2) may be opposed to each other with their cathode portions (2b) and (2b) facing inward, as shown in FIG. The cathode part (2b) of the element (2) may be overlapped and joined together.

Further, although the capacitor element (2) is formed by laminating a plurality of anode bodies (20) and (20), it may be formed from a sintered body of valve metal instead.
(Second embodiment)
FIG. 6 is a perspective view of another solid electrolytic capacitor (1). This is because the capacitor elements (2) and (2) in which the anode parts (2a) and (2a) are arranged in parallel with each other as shown in FIG. A plurality are provided along the horizontal direction (A in FIG. 6) to form an array. The capacitor elements (2) and (2) are covered with a housing (70). By cutting the housing (70) with a dicing saw or the like along the dotted line in FIG. 6, a capacitor having a desired capacitance can be obtained according to customer needs.

  In this example, in addition to the above effect, a plurality of capacitor elements (2) and (2) share one anode-side lead frame (9), so that an extra capacitor mounting space is eliminated. In addition, the length of the wiring connecting the capacitor elements (2) and (2) can be shortened.

  The manufacturing method of the solid electrolytic capacitor (1) of FIG. 6 is shown. In the following description, two capacitor elements (2) and (2) are provided along the horizontal direction substantially orthogonal to the arrangement direction of the lead frames (9) and (90), but this is for the convenience of illustration. Three or more may be sufficient.

  First, as shown in FIG. 7, the metal plate (8) to be the lead frames (9) and (90) is punched out, and the two slots (80) and (80) to be the openings (92) are opened substantially in parallel. To do. Between the slots (80) and (80) on the metal plate (8) is the anode side lead frame (9), and the outside of the slots (80) and (80) is the cathode side lead frame (90). Concave surfaces (91) are formed in advance on the back surfaces of the portions to be the anode side and cathode side lead frames (9), (90). On the metal plate (8), through holes (81) and (81) are formed at substantially equal intervals along a horizontal direction substantially orthogonal to the arrangement direction of the lead frames (9) and (90). 81) (81) and the slot (80) are filled with resin forming the housing (70).

  On the metal plate (8), the anode parts (2a) and (2a) of the two capacitor elements (2) and (2) are placed facing each other between the slots (80) and (80), and resistance welding is performed. Install. On the metal plate (8), the cathode part (2b) of the capacitor element (2) is placed outside the slot (80) (80), and the cathode part (2b) is placed on the metal plate by a conductive adhesive. (8) Mounted on top. That is, the capacitor element (2) is attached across the slot (80).

  A jig receiving hole (82) is formed at the corner of the metal plate (8), and the jig receiving hole (82) of the metal plate (8) to which the capacitor element (2) is attached is received by the jig ( (Not shown). As shown in FIG. 8, the periphery of the capacitor element (2) is covered with a resin block (7) by injection molding of molten resin or screen printing. The resin block (7) is broken at the plane including the DD line and the EE line in FIG. 8 to form a housing (70) to obtain the solid electrolytic capacitor (1) in FIG.

  The applicant cuts the housing (70) according to the cut position indicated by the dotted line in FIG. 6, and determines the values of capacitance (unit: μF), ESR (unit: mΩ), and ESL (unit: nH) shown in Table 1. Obtained. Here, 1P to 4P indicates the number of pairs of capacitor elements (2) and (2) facing the anode part (2a). The rated voltage is 2V.

  As described above, ESR and ESL can be reduced while increasing the capacitance by arranging the capacitor elements (2) in parallel in an array. Further, it is possible to eliminate an extra space for mounting the capacitor, and it is possible to shorten the length of the wiring connecting the capacitor elements (2) and (2).

  6 shows the capacitor element (2) in which the anode portions (2a) and (2a) are opposed to each other, the cathode portions (2b) and (2b) may be opposed to each other. In the above description, two capacitor elements (2) and (2) are provided along the lateral direction, but three or more capacitor elements (2) and (2) may be provided.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

(1) Solid electrolytic capacitor (2) Capacitor element (9) Lead frame (20) Anode body (70) Housing (90) Lead frame

Claims (1)

A flat capacitor element having an anode part and a cathode part, an anode side lead frame connected to the anode part, a cathode side lead frame connected to the cathode part, the capacitor element, and the anode side lead frame And a housing that covers the cathode side lead frame, and a solid electrolytic capacitor in which a part of the anode side lead frame and a part of the cathode side lead frame are exposed from the lower surface of the housing,
The anode-side lead frame has a first portion having a surface exposed from the lower surface of the housing, and a second portion having a thickness thinner than the first portion and the lower surface side covered with the housing,
The anode part is joined to the upper surface of the second part by resistance welding,
The lower surface of the second part has a resistance welding mark formed by the resistance welding,
The solid electrolytic capacitor , wherein the resistance welding trace is covered with the housing .

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