JP2010097968A - Multilayer solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer solid electrolytic capacitor in which a leakage current fraction defective is reduced. <P>SOLUTION: For a solid electrolytic capacitor element, a valve action metal with a dielectric formed on the surface serves as an anode body 1, a solid electrolytic layer comprising a conductive high polymer layer 5 and a cathode layer comprising a graphite layer 6 and a silver paste layer 7 are successively formed at the cathode part of the anode body 1, and a metal frame 8 extended from the end part of the anode body is connected to the anode part of the anode body 1. The plurality of solid electrolytic capacitor elements are laminated, and the metal frames are connected to each other through a conductive material comprising high temperature solder 10 at a part extended from the end part of the anode body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer solid electrolytic capacitor used in various electronic devices.

  In recent years, with the increase in speed, integration, and miniaturization of CPUs, memories, and image processing chips, capacitors are required to have low impedance, downsizing, thinning, and high reliability. There are some that meet this requirement by using many connected in parallel.

  In recent years, development of large-capacity, low-impedance solid electrolytic capacitors that can replace dozens of multilayer ceramic capacitors with one has been promoted, and a structure in which solid electrolytic capacitor elements are connected in parallel and stacked is adopted. ing.

  For example, in Patent Document 1, a metal frame for height adjustment (described as a spacer in Patent Document 1) is arranged between the anode portions of a plurality of capacitor elements, and after laminating, resistance welding is performed to make it conductive. A solid electrolytic capacitor that reduces LC defects associated with bending deformation due to welding is disclosed.

JP 2003-243257 A

  However, in Patent Document 1, after laminating the metal frame and the anode portion of the solid electrolytic capacitor element, the anode portion of the laminated solid electrolytic capacitor element in which the valve metal and the metal frame are alternately laminated is integrally joined by resistance welding. In this case, the oxide film on the surface of the valve action metal becomes a large resistance, making it difficult for current to flow, causing a problem that only a part of the metal is welded or not welded at all.

  In order to solve this problem, it is conceivable to increase the welding current or to perform welding by laser welding. However, when welding is performed by such a method, molten metal fume is scattered between the positive and negative electrodes. As a result, there are new problems such as occurrence of a short circuit, thinning of the exterior resin on the scattered metal fume, and deterioration of airtightness. Furthermore, when joining together multiple solid electrolytic capacitor elements with metal frames by resistance welding or laser welding, pressurization is performed so as to crush the gap generated between the solid electrolytic capacitor anode parts with metal frames. Therefore, there was another problem that a crack occurred in the valve action metal oxide film due to stress due to pressurization, resulting in a leakage current failure.

  The present invention has been made in order to solve the above-mentioned problems, and the technical problem thereof is a stacked solid electrolysis that ensures good electrical characteristics in the connection of the anode part and reduces the leakage current failure rate. It is to provide a capacitor.

  The present invention provides means for solving the above-mentioned problems, and its configuration is as follows.

  The multilayer solid electrolytic capacitor of the present invention uses a flat valve-acting metal having a dielectric formed of an oxide film on the surface as an anode body, and a solid electrolyte layer and a cathode layer are sequentially formed on the cathode portion of the anode body. A plurality of solid electrolytic capacitor elements in which a metal frame extending from an end portion of the anode body is connected to the anode portion of the anode body, and the metal frames are extended from the end portion of the anode body via a conductive material. It is connected.

  Further, the conductive material is high-temperature solder or a conductive adhesive.

  According to the present invention, in the connection between the metal frames of the solid electrolytic capacitor element in the multilayer solid electrolytic capacitor, the metal frame is located outside the end of the anode body and has a low connection resistance via a conductive adhesive or high-temperature solder. Since it is connected to the frames with a certain connection area, the connection resistance can be kept low even when the number of stacked layers is increased, and the low ESR characteristic of the stacked solid electrolytic capacitor can be fully exploited. Furthermore, since resistance welding and laser welding are not used to connect the solid electrolytic capacitor anode part, there is no pressurization of the laminated solid electrolytic capacitor anode part, and cracks occur in the valve metal oxide film due to stress due to pressurization. A leakage current failure does not occur, and the leakage current failure rate can be reduced.

  Embodiments of the present invention will be described below.

  In the present invention, a dielectric material composed of an oxide film is formed by anodic oxidation on the surface of a roughened flat valve metal such as aluminum, and then an epoxy resin or the like is used to divide the anode portion and the cathode portion. A resist layer is formed, and a cathode layer composed of a solid electrolyte layer, a graphite layer, and a silver paste layer is sequentially formed on the anodized film of the cathode portion divided by the resist layer, and the valve action metal divided by the resist layer is formed. A metal frame disposed so as to extend from the end of the anode body to the anode portion of the remaining portion opposite to the cathode portion side is ultrasonically welded to obtain a solid electrolytic capacitor element with a metal frame. Thereafter, a plurality of solid electrolytic capacitor elements with metal frames are laminated, the cathode part is bonded and conductive with a conductive adhesive, and the anode part is melted at a high temperature solder (once at 220 degrees or more, and then re-solidified, the melting point becomes The solder that reaches 280 ° C. or higher is referred to as a high-temperature solder) or is bonded and conductive with a conductive adhesive.

  In this way, the metal frames of the solid electrolytic capacitor element with the metal frame are stacked one above the other, and the metal frame of the other solid electrolytic capacitor element with the metal frame and the metal frame outside the anode body made of the valve metal are stretched. It is set as the solid electrolytic capacitor element laminated body connected in the part. After that, copper foil on both sides of the insulating layer is formed on the anode part and cathode part of the solid electrolytic capacitor element by etching or the like, and the inside of the insulating layer is connected with vias to connect external terminals. A solid electrolytic capacitor element laminate is connected to a substrate with a conductive adhesive and is covered with a sealing resin to form a laminated solid electrolytic capacitor.

  When connecting the multilayer solid electrolytic capacitor to the double-sided copper-clad substrate, the anode portion may be connected with a high-temperature solder after the cathode portion is bonded with a conductive adhesive. Furthermore, after stacking a plurality of solid electrolytic capacitor elements with metal frames and connecting only the cathode part to the solid electrolytic capacitor element and the double-sided copper-clad substrate with a conductive adhesive at a time, connection of the anode part of the solid electrolytic capacitor element laminate And a double-sided copper-clad substrate anode part may be connected at once using high-temperature solder. The order and combination of materials are not limited to this in the lamination process and the double-sided copper-clad substrate connection process.

  Furthermore, for the exterior of the multilayer solid electrolytic capacitor, a double-sided copper-clad substrate may be used, or a lead frame for connecting an external circuit is connected to the cathode part, sealed with an exterior resin, and the lead frame is bent. The structure may be different.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
1 is a cross-sectional view of a multilayer solid electrolytic capacitor according to Example 1 of the present invention. First, an anode body widened layer 2 formed by roughening a valve metal anode body 1 made of a flat aluminum foil is anodized to form an anodized film 3, and then a resist is used to separate the positive and negative electrodes. Layer 4 is formed. Thereafter, a conductive polymer layer 5 serving as a solid electrolyte is formed on the anodized film 3 serving as a cathode portion, and a graphite layer 6 and a silver paste layer 7 are sequentially formed as a current collector. Thereafter, a metal frame 8 having dimensions of 0.8 × 4.3 × 0.15 mm obtained by sequentially plating nickel, copper, and silver plating using copper as a base material on the anode section separated by the resist layer 4 is the cathode side. Extending 0.1 mm from the end of anode body 1 in the opposite direction, exposed, and welded by ultrasonic welding to obtain a solid electrolytic capacitor element with a metal frame of dimensions 8.2 × 4.5 × 0.3 mm.

  Thereafter, five solid electrolytic capacitor elements with metal frames are stacked, and the cathode portions are bonded with a conductive adhesive 9 so as to be connected in parallel, and the high-temperature solder 10 is attached to the metal frame 8 of the solid electrolytic capacitor elements with metal frames. Is applied and melted in an atmosphere of 240 ° C. for 10 seconds to bond the anode parts together to obtain a solid electrolytic capacitor element laminate. In order to connect the solid electrolytic capacitor element laminate thus obtained to external terminals, the copper foils on both sides of the insulating layer are etched to the same cathode and anode pattern as the solid electrolytic capacitor element, and the inside of the insulating layer is connected by vias 11. A solid electrolytic capacitor element laminate is connected to the double-sided copper-clad substrate 12 with a conductive adhesive 13 and is packaged with a sealing resin 14 so as to have a size of 8.5 × 5.3 × 2.0 mm. It was. Table 1 shows the ESR average value and leakage current failure rate at a frequency of 100 kHz of 30 multilayer solid electrolytic capacitors of Example 1.

(Example 2)
The multilayer solid electrolytic capacitor in Example 2 is a multilayer solid electrolytic capacitor shown in Example 1, with the distance of the metal frame extending from the end face of the anode body made of a valve action metal exposed to 0.2 mm. Other configurations are the same as those in the first embodiment, and the drawings are omitted. Table 1 shows the ESR average value and the leakage current defect rate at the frequency of 100 kHz of the 30 stacked solid electrolytic capacitors according to Example 2 configured as described above.

(Example 3)
The form in Example 3 is such that the distance of the metal frame that extends from the end face of the anode body made of valve metal and is exposed to the multilayer solid electrolytic capacitor shown in Example 1 is 0.3 mm. Since the configuration is the same as that of the first embodiment, the drawings are omitted. Table 1 shows the ESR average value and leakage current failure rate at a frequency of 100 kHz of 30 multilayer solid electrolytic capacitors of Example 3 configured as described above.

(Comparative Example 1)
FIG. 2 is a cross-sectional view of the multilayer solid electrolytic capacitor of Comparative Example 1 configured according to the prior art. That is, the form in Comparative Example 1 is a distance of the metal frame exposed from the end face of the anode body made of a valve metal, which is a conventional technique, to the multilayer solid electrolytic capacitor shown in Example 1 is 0 mm (the metal frame from the end face of the anode). A plurality of solid electrolytic capacitor elements with a metal frame were laminated, and the anode part of the solid electrolytic capacitor element laminate in which the valve action metal anode part and the metal frame were alternately laminated were laminated by laser welding. The anode part and the metal frame are fusion-bonded, and the other configuration is the same as that of the first embodiment. Table 1 shows the ESR average value, the ESR average value, and the leakage current failure rate at the frequency of 100 kHz of the 30 stacked solid electrolytic capacitors according to Comparative Example 1 configured as described above.

(Comparative Example 2)
The form in Comparative Example 2 is that in which the distance of the metal frame exposed from the end face of the anode body made of valve metal is 0 mm (the metal frame is not exposed from the end face of the anode) with respect to the multilayer solid electrolytic capacitor shown in Example 1. Since the other configuration is the same as that of the first embodiment, the drawing is omitted. Table 1 shows the ESR average value and leakage current failure rate at a frequency of 100 kHz of 30 multilayer solid electrolytic capacitors of Example 3 configured as described above.

  As described above, the multilayer solid electrolytic capacitor fabricated using the present invention can suppress ESR lower than the multilayer solid electrolytic capacitor fabricated by the prior art, and can reduce the leakage current defect rate. Is possible.

Sectional drawing of the multilayer solid electrolytic capacitor in Example 1 of this invention. Sectional drawing of the laminated type solid electrolytic capacitor of the comparative example 1 produced with the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode body 2 Anode body expansion layer 3 Anodized film 4 Resist layer 5 Conductive polymer layer 6 Graphite layer 7 Silver paste layer 8 Metal frame 9 Conductive adhesive 10 High temperature solder 11 Via 12 Double-sided copper-clad substrate 13 Conductivity Adhesive 14 Sealing resin 15 Laser weld

Claims (2)

  A flat valve-acting metal having an oxide film formed on its surface is used as an anode body, a solid electrolyte layer and a cathode layer are sequentially formed on the cathode portion of the anode body, and an anode body on the anode portion of the anode body A multilayer type in which a plurality of solid electrolytic capacitor elements connected to a metal frame extending from an end are stacked, and the metal frames are connected via a conductive material at a portion extending from an end of the anode body Solid electrolytic capacitor.   The multilayer solid electrolytic capacitor according to claim 1, wherein the conductive material is high-temperature solder or a conductive adhesive.

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