JP2009065059A - Solid electrolytic capacitor and connection structure for solid electrolytic capacitor to mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor which has a low ESR and a low ESL and is superior in transient responsiveness. <P>SOLUTION: A first element A having a plurality of anode terminal parts and a second element B forming a transmission line are laminated to form a solid electrolytic capacitor. In the first element A, a cathode electrode layer comprising a dielectric oxide coating film 4, a solid electrolyte 5, and a conductive member 6 is provided on a connection surface of a valve action metal substrate 1 to a mounting substrate, and cathode parts b1 to bn are formed. A plurality of anode terminal parts a1 to an which are formed integrally with the valve action metal substrate 1 and have surfaces exposed to positions level with the cathode electrode layer are formed in part of a region forming cathode pats c1 and c2 in the valve action metal substrate 1. In the second element, a cathode electrode layer comprising a dielectric oxide coating film 14, a solid electrolyte 15, and a conductive member 16 is provided on both surfaces of a valve action metal substrate 1 to form a cathode part 20 for transmission line formation. The solid electrolytic capacitor is connected to the mounting substrate so that the second element is on the power source side and the first element is on the load side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor having excellent transient response and low impedance up to a high frequency region, and a connection structure of a solid electrolytic capacitor to a mounting substrate.

  In order to cope with the stabilization of power supply voltage of LSIs and the like that operate with a large current and low voltage as electronic circuits become more digitized, a capacitor with a high transient response capable of supplying charges at a sufficiently high speed is desired.

  On the other hand, a high-frequency low-impedance element is desired to cut off high-frequency current from LSIs with higher frequencies from the power supply system, but conventional 2-terminal capacitors interpose metal lead terminals and the like for connection to the circuit. For this reason, the wiring circuit length becomes longer, the ESR / ESL is large, the transient response is poor, and even if a noise filter circuit is configured by combining two-terminal capacitors, the impedance can be sufficiently lowered to the high frequency range. Absent.

  In order to solve such a problem, as shown in Patent Document 1 or Patent Document 2, by disposing the cathode terminal portion and the anode terminal portion alternately on the same surface, the cathode and the anode are alternately arranged to reduce the ESR. In addition, there is disclosed a solid electrolytic capacitor in which transient response is reduced by canceling and reducing ESL. However, although the technique of Patent Document 1 or Patent Document 2 can lower the impedance up to the high frequency region as compared with the conventional technology, there is a problem that the impedance increases in the high frequency region above a certain frequency.

  Further, in the distributed constant type noise filter disclosed in Patent Document 3, by using a transmission line structure, it is possible to block a high-frequency current in a wide band up to a high-frequency region, and an electrode terminal serves as a mounting surface. By arranging them on the lower surface and bringing the cathode and cathode terminals closer together, transient response is improved by achieving low ESR and low ESL.

  Regarding the improvement of the transient response, since further increase in current and voltage of electronic circuits is progressing year by year, further improvement of transient response is required not only for the noise filter of Patent Document 3, but also for capacitors. However, no capacitor has been proposed so far that satisfies such requirements.

Japanese Patent Laid-Open No. 2002-237431 JP 2005-142437 A JP 2002-164760 A

  The present invention has been made against the background of the conventional technical problems as described above. The purpose of the present invention is to improve the transient response by lowering the ESR and ESL, and to increase the high-frequency current by lowering the impedance up to the high-frequency region. It is an object of the present invention to provide a solid electrolytic capacitor and a connection structure of a solid electrolytic capacitor to a mounting substrate that can block the above.

  In order to achieve the above object, the invention of claim 1 is directed to a dielectric oxide film on a connecting surface of a flat valve-acting metal base with a mounting substrate, and a solid electrolyte and a conductive member on the dielectric oxide film. A first capacitor element in which a plurality of anode terminal portions connected to the valve action metal substrate are formed in a region of the cathode portion; and a flat plate shape. A pair of anode terminal portions is formed on the valve action metal substrate, and a dielectric oxide film is formed on both surfaces of the valve action metal substrate, and a cathode electrode layer made of a solid electrolyte and a conductive member is sequentially formed on the dielectric oxide film. A second capacitor element formed with a provided cathode portion, and the first and second capacitor elements are in the form of a plate with the anode terminal portions of the first and second capacitors being independent from each other. Valve action metal substrate thickness Characterized in that it is laminated to.

  According to a second aspect of the present invention, in the first aspect of the invention, the second capacitor element has a portion in which the cathode electrode layers formed on both the front and back surfaces of the valve action metal substrate are opposed to each other. A transmission line structure is formed in a region including a dielectric oxide film sandwiched between a cathode electrode layer and a valve metal substrate that are arranged to face each other.

  According to a third aspect of the present invention, there is provided a connection structure for mounting a solid electrolytic capacitor according to the first or second aspect, wherein one anode terminal portion of the second capacitor element is connectable to a power source. And the other anode terminal portion of the second capacitor element is electrically connected to the output power conductor layer of the mounting substrate connectable to a load circuit, and the second capacitor element An output power supply conductor layer of the mounting substrate in which the cathode electrode layer of the capacitor element is electrically connected to the ground conductor layer of the mounting substrate, and the anode terminal portion of the first capacitor capacitor element is connectable to a load circuit component The cathode electrode layer of the first capacitor element is electrically connected to the ground conductor layer of the mounting substrate.

  According to the present invention, by providing the anode terminal portion in the cathode portion region of the first capacitor element, it is possible to shorten the arrangement circuit length, and the ESR is reduced and the ESL cancels each other and is reduced. In addition, the provision of a plurality of anode terminal portions increases the charge supply path, so that transient response is improved. On the other hand, the second capacitor element of the transmission line structure becomes a part of the power supply conductor layer pattern. It is possible to cut off the high frequency current up to the high frequency region in a wide band.

  Further, in the connection structure of the solid electrolytic capacitor to the mounting substrate of the present invention, the power line conductor layer and the output power conductor layer are connected through the transmission line structure region of the solid electrolytic capacitor, and the high frequency noise current is generated in the power supply system. Is cut off from. In addition, since the connection structure has a larger number of charge supply paths, the transient response is good.

(1) First Embodiment Hereinafter, a first embodiment of the present invention will be specifically described with reference to the drawings.
The solid electrolytic capacitor of the present invention is formed by laminating a first capacitor element A having a large number of anode terminal portions and a second capacitor element B forming a transmission line, and FIG. FIG. 2 is a cross-sectional view showing a first embodiment of the first capacitor element A constituting the solid electrolytic capacitor of the present invention, and FIG. 2 is a plan view seen from the connection surface side to the mounting substrate.

  In the figure, reference numeral 1 denotes a flat valve metal substrate, and a dielectric oxide film 4 is formed on the lower surface of the valve metal substrate 1 (connection surface to the mounting substrate). A cathode electrode layer composed of the solid electrolyte 5 and the conductive member 6 is sequentially provided on the surface of the oxide film 4 to form cathode portions b1 to bn (n = 5 in the figure).

  A plurality of anode terminal portions a1 which are formed integrally with the valve action metal substrate 1 in a part of the region forming the cathode portions b1 to bn in the valve action metal substrate 1 and whose surfaces are exposed to the surface positions of the cathode electrode layer. ~ An (n = 4 in the example in the figure) are formed. In this case, if the anode terminal portion is electrically connected to the main body of the valve action metal substrate 1, the anode terminal portion may be formed by joining another member even if it is formed by protruding a part of the valve action metal substrate 1. Also good. Moreover, the insulating member 8 is provided in the outer peripheral part (boundary surface with anode terminal part a1-an) of cathode part b1-bn.

  On the other hand, a dielectric oxide film 14 is formed on the upper surface (the surface opposite to the connection surface to the mounting substrate) of the valve action metal base 1, and the solid electrolyte 15 and the conductive material are formed on the surface of the dielectric oxide film 14. A cathode electrode layer made of the conductive member 16 is provided. In FIG. 1, the end portion of the valve metal base 1 is covered with the dielectric oxide films 4 and 14, but may be covered with an insulating member.

  In the embodiment of FIGS. 1 and 2, the cathode portions b1 to bn and the anode terminal portions a1 to an are alternately formed along the longitudinal direction of the rectangular valve action metal substrate 1, but these shapes and The number and arrangement location are not limited to those shown in FIGS.

  For example, as shown in FIG. 3, a plurality of circular anode terminal portions a1 to an (n = 4 in the example of FIG. 4) and a plurality of cathode portions b1 to bn (n = 4) disposed adjacent to the anode terminal portions a1 to an In the example of FIG. 4, n = 4) can be formed. Also, as shown in FIG. 4, the anode terminal portions a1 to an (n = 4 in the example in the figure) have a quadrangular shape, and at a certain interval on one edge of the dielectric oxide film 4 and the cathode electrode layer portion. A plurality can be arranged.

  Next, a second capacitor element B (capacitor element B for forming a transmission line) stacked on the first capacitor element A having the above-described configuration will be described with reference to FIG.

  The second capacitor element B is provided with anode terminal portions c1 and c2 exposed to the outside at both ends of the valve-acting metal base 21 at the center, and dielectrics on both surfaces of the valve-acting metal base 21, respectively. An oxide film 24 is formed, and a cathode electrode layer comprising a solid electrolyte 25 and a conductive member 26 is sequentially provided on the surface of the dielectric oxide film 24. The dielectric oxide film 24 and the periphery of the cathode electrode layer are insulated by an insulating member 28.

  As shown in FIG. 6, the solid electrolytic capacitor of the present embodiment includes a second capacitor element on a surface opposite to the connection surface to the mounting substrate in the first capacitor element A having the above-described configuration. Is a laminate of B. In this case, the cathode portions of the first and second capacitor elements A and B are connected to the ground conductor in common with the conductive members 16 and 26 of the two elements being connected by a conductive adhesive 27 or the like in this embodiment. It may be connected to a layer, or both elements may be connected to the ground. A terminal portion on the ground side (ground side) of the second capacitor element B is indicated by d1 in the drawing.

  As for the anode terminal portion, the first and second capacitor elements A and B terminals are independent, and the anode terminal portions a1 to an of the first capacitor element A are all separately connected to the output power supply conductor layer. One anode terminal portion c1 of the capacitor element 2 is connected to the power source, and the other anode terminal portion c2 is connected to the output power source conductor layer.

  Next, a configuration for connecting the solid electrolytic capacitor according to the first embodiment having the above-described configuration to a mounting substrate will be described with reference to FIG. That is, in FIG. 7, reference numeral 51 denotes a mounting substrate, on which the solid electrolytic capacitor 52 of the first embodiment is mounted, and a load circuit component 53 such as an IC is mounted on the opposite surface.

  On the mounting board 51, a power line conductor layer 54a connected to the power source 54, an output power conductor layer 54b connected to the power line conductor layer 54a, and the power line conductor layer 54a and the output power conductor layer 54b are formed. A capacitor anode terminal connecting portion 54c and a load circuit component connecting portion 54d are provided.

  The capacitor anode terminal connection portion 54c is aligned with the positions of the anode terminal portions a1 to an exposed on the mounting substrate connection surface of the first capacitor element A and the anode terminal portions c1 and c2 of the second capacitor element B. A plurality of terminals provided. The load circuit component connecting portion 54d includes a plurality of terminals provided in accordance with the positions of the plurality of anode connection terminals provided in the load circuit component 53.

  Similarly, the mounting substrate 51 is provided with a ground (ground side) conductor layer 55a. The ground conductor layer 55a is also provided with a capacitor cathode portion connecting portion 55c and a load circuit component connecting portion 55d.

  The capacitor cathode terminal connection portion 55c includes a plurality of terminals provided in accordance with the positions of the plurality of cathode portions b1 to bn exposed on the mounting substrate connection surface of the first capacitor element A. The load circuit component connecting portion 55d includes two terminals provided in accordance with the positions of the two cathode connection terminals for the first capacitor element A and the second capacitor element B. Similarly, it is connected to two cathode connection terminals provided on the load circuit component 53.

  Next, the operation of the first embodiment having the above configuration will be described with reference to FIG. 1 and FIGS.

  As shown in the cross-sectional view of FIG. 1, the first capacitor element A disposed on the mounting substrate 51 has a dielectric oxide film 4 on both sides of the flat valve-acting metal substrate 1 disposed at the center thereof. , 14 and the cathode electrode layer, and a plurality of anode terminal portions a1 to an and corresponding cathode portions b1 to bn are formed on the connection surface side to the mounting substrate.

  Therefore, as shown in FIG. 7, each anode terminal part a1 to an is connected to a capacitor anode terminal connection part 54c extending from the power line conductor layer 54a, and each cathode part b1 to bn is connected to a capacitor cathode part in the ground conductor layer 55a. When connected to the portion 55c, a plurality of capacitors are connected in parallel between the first capacitor element A and the load circuit component 53, as shown in the electric circuit diagram of FIG.

  On the other hand, as shown in FIG. 7, on the power source side of the first capacitor element A, the second capacitor element B is connected to the capacitor anode terminal connection portion 54c extending from the power line conductor layer 54a with the anode terminals c1 and c2 thereof. When the cathode part d1 is connected to the capacitor cathode part connection part 55c in the ground conductor layer 55a, a plurality of capacitors formed by the first capacitor element a are arranged in parallel as shown in the electric circuit diagram of FIG. A transmission line is formed on the power supply side of the connection structure.

  This transmission line corresponds to a circled portion in FIG. 5 showing the second capacitor element B. This portion is a region where the anode terminal portion is not formed, and a configuration in which the dielectric oxide film 14 and the cathode electrode layer are formed on both surfaces of the valve action metal base 21 (also referred to as two main surfaces). It has become. This configuration is called a transmission line, and the impedance when a high-frequency current passes through this structure is called characteristic impedance, and shows a characteristic that takes a constant value even when the frequency changes.

The transmission line is shown by the equivalent circuit shown in FIG. 9, and its impedance is a lumped constant circuit in the low frequency region, whereas this is a distributed constant circuit (transmission line) in the high frequency region, and Z = (L / C) A constant value of ^1/2 (see FIG. 10). For this reason, there is no increase in impedance in the high frequency region, and very good high frequency current cutoff characteristics are exhibited.

  Note that the equivalent circuit in FIG. 9 shows an equivalent circuit for each transmission line. The reason why a large number of circuits are arranged together is that a) a case of flowing at a low frequency is regarded as one set of equivalent circuits. B) When the frequency becomes high, the wavelength is shortened so that the line looks relatively long, and a distributed constant circuit (constant characteristic impedance) that seems to have a number of sets of equivalent circuits connected together is obtained.

On the other hand, reduction of equivalent series inductance (ESL) is important for improving transient response in order to supply charges at a sufficient speed. The points of ESL reduction are as follows.
(1) Shorten the current path (wiring length).
(2) To cancel the magnetic field formed by the current flowing through the current path with the magnetic field formed by the current flowing through another current path.
(3) The current path is divided into n and the ESL is substantially 1 / n.

On the other hand, in the first embodiment, very good characteristics can be obtained as transient response for the following reason.
(a) The anode terminal portion and the cathode portion are taken out from the same surface (lower surface: connection surface to the mounting substrate), and the wiring path can be shortened.
(b) The anode and the cathode are alternately arranged in the vicinity so that the ESL is offset.
(c) The current path can be arbitrarily increased, and ESL can be reduced.

  As described above, according to the present embodiment, the first capacitor element A plays a role as a charge supply capacitor corresponding to each anode terminal. That is, the first capacitor element A for improving the transient response in which the second capacitor element B constituting the transmission line is connected to the power supply side, is not connected to the power supply, and is taken in and out of the load circuit. As a result, the transient response can be improved by reducing the ESR and ESL, and the high frequency current can be cut off by reducing the impedance up to the high frequency region.

(2) Other Embodiments The present invention is not limited to the embodiment as described above, but includes the following other embodiments.

(1) Since the first capacitor element A plays a role of forming a plurality of charge supply capacitors, it functions if there is a cathode portion and an anode terminal portion provided on the mounting substrate side. Therefore, it is not necessary to provide a cathode part on the opposite surface of the valve action metal base | substrate 1 like FIG. However, in view of the possibility of connection with the second capacitor and the capacity, it is advantageous to have a cathode portion on the opposite side of the valve metal base.

(2) A plurality of second capacitor elements B constituting the transmission line are stacked after the first capacitor element A having the anode terminal portion, and the first capacitor element A is mounted on the mounting board. A plurality of power supplies can be connected.

Sectional drawing which shows an example of the 1st capacitor | condenser element A in this invention. FIG. 2 is a plan view of the first capacitor element A of FIG. The top view by the side of the mounting board connection surface in the modification of the 1st capacitor | condenser element A of this invention. The top view by the side of the mounting board connection surface in the other modification of the 1st capacitor | condenser element A of this invention. Sectional drawing of the 2nd capacitor | condenser element B in this invention. Sectional drawing of the solid electrolytic capacitor of 1st Embodiment of this invention. Sectional drawing which shows the structure which connected the solid capacitor of FIG. 6 to the mounting board | substrate. The electric circuit diagram in the connection structure to the mounting substrate of FIG. The circuit diagram which shows the equivalent circuit of the transmission line in this invention. The graph which shows the impedance characteristic of a transmission line.

Explanation of symbols

A ... 1st capacitor element B ... 2nd capacitor element a1-an ... Anode terminal part b1-bn of 2nd capacitor element ... Cathode part c1, c2 ... Anode terminal part 1 of 1st capacitor element ... Valve action Metal substrates 4 and 14 Dielectric oxide films 5 and 15 Solid electrolytes 6 and 16 Conductive members 8 and 18 Insulating member 20 Cathode portion 51 Mounting substrate 52 Solid electrolytic capacitor 53 Load circuit component 54 Power source 54a power line conductor layer 54b ... output power supply layer 54c ... capacitor anode terminal connection 54d ... load circuit component connection 55a ... ground (ground side) conductor layer 55c ... capacitor cathode terminal connection 55d ... load circuit component connection

Claims (3)

On the connection surface of the flat valve action metal substrate to the mounting substrate, a cathode portion is formed by sequentially providing a dielectric oxide film and a cathode electrode layer made of a solid electrolyte and a conductive member on the dielectric oxide film. A first capacitor element in which a plurality of anode terminal portions connected to the valve metal substrate are formed in a region of the cathode portion;
A pair of anode terminal portions are formed on a flat valve-acting metal base, a dielectric oxide film is formed on both surfaces of the valve-acting metal base, and a cathode electrode layer comprising a solid electrolyte and a conductive member on the dielectric oxide film. And a second capacitor element formed by forming a cathode part provided sequentially,
The first and second capacitor elements are laminated in the thickness direction of the flat valve metal substrate with the anode terminal portions of the first and second capacitors being independent from each other. Solid electrolytic capacitor.   The second capacitor element has a portion in which the cathode electrode layers formed on the front and back surfaces of the valve action metal substrate are arranged opposite to each other, and is sandwiched between the cathode electrode layer arranged opposite to the valve action metal substrate. 2. The solid electrolytic capacitor according to claim 1, wherein a transmission line structure is formed in a region including the dielectric oxide film. In the connection structure to the mounting substrate of the solid electrolytic capacitor according to claim 1 or 2,
One anode terminal portion of the second capacitor element is electrically connected to a power line conductor layer of a mounting substrate connectable to a power source;
The other anode terminal portion of the second capacitor element is electrically connected to the output power supply conductor layer of the mounting substrate connectable to the load circuit;
The cathode electrode layer of the second capacitor element is electrically connected to the ground conductor layer of the mounting substrate;
An anode terminal portion of the first capacitor capacitor element is electrically connected to an output power supply conductor layer of a mounting substrate connectable to a load circuit component;
A structure for connecting a solid electrolytic capacitor to a mounting board, wherein the cathode electrode layer of the first capacitor element is electrically connected to a ground conductor layer of the mounting board.