JP2008130858A - Chip-shaped solid-state electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-shaped solid-sate electrolytic capacitor reduced in ESR (equivalent series resistance) through lead frameless chip type. <P>SOLUTION: The chip-shaped solid-state electrolytic capacitor is constituted, such that the outer peripheral surface excluding an anode lead-out line for a capacitor element, consisting of an oxide film layer provided on the surface of an anode body formed of metallic powder for valve effect through pressurizing formation and anode lead-out line is planted on the surface of the anode body; a solid-state electrolytic layer and a cathode lead-out layer are coated by insulating resin; and more than one layer of conductor layers are formed on an anode lead-out unit consisting of the anode lead-out line that is not applied with the resin coating, and the peripheral part thereof, as well as, the cathode lead-out unit on a surface opposed to the anode lead-out line to employ as electrodes. Furthermore, the cathode lead-out unit is provided on a surface, facing the planting surface of anode lead-out lines of the capacitor element and at a position facing the substrate mounting part of at least the cathode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor, and more particularly to a structure of a chip-shaped solid electrolytic capacitor with reduced ESR.

A conventional solid electrolytic capacitor is manufactured by the following method.
First, a valve action metal powder such as tantalum or niobium is pressure-molded, and an oxide film layer, a solid electrolyte layer, and a cathode lead layer are sequentially formed on the surface of the anode body on which the anode lead-out line is planted to produce a capacitor element.
Then, the outer peripheral surface excluding the anode lead-out portion and the surface facing the anode lead-out portion of the capacitor element is sheathed with an insulating resin, and the anode lead-out line not provided with the resin sheath, its peripheral portion (anode lead-out portion), and the bottom surface At least one conductor layer is formed on each (cathode lead-out portion) to form an electrode to produce a chip-shaped solid electrolytic capacitor (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-22293

  However, in the solid electrolytic capacitor manufactured by the method of Patent Document 1, the cathode lead-out portion is limited to the bottom surface, and there is a problem that the ESR value becomes high because the area of the lead-out and introduction portion of current during charge / discharge is small. .

  In addition, the capacitor element has become thinner in response to the recent reduction in the height of products, and the cathode lead area of the capacitor element has been further reduced accordingly. The decrease in efficiency is becoming more pronounced. Further, when the circuit in which the capacitor is used is increased in frequency, the efficiency is further lowered.

The present invention solves the above-mentioned problems, and is a capacitor formed by pressure forming a valve action metal powder and forming an oxide film layer, a solid electrolyte layer, and a cathode lead layer on the surface of an anode body on which an anode lead-out line is implanted. An outer peripheral surface excluding the anode lead-out line of the device and the cathode lead-out part provided in a part of the cathode lead-out layer is sheathed with an insulating resin, an anode lead-out line not provided with the resin sheath and an anode lead-out part composed of the peripheral part, and In a chip-shaped solid electrolytic capacitor in which one or more conductor layers are formed on the cathode lead-out portion on the surface opposite to the planting surface of the anode lead-out wire to form an electrode,
A chip-shaped solid electrolytic capacitor in which the cathode lead-out portion is provided on a surface facing the planting surface of the anode lead-out line of the capacitor element and at least a position corresponding to the substrate mounting portion of the cathode.

  According to the present invention, since the current derivation and introduction area of the cathode lead-out portion can be expanded conventionally, the efficiency of derivation and introduction of current during charge / discharge is improved, so that ESR can be reduced.

Embodiments of the present invention will be described below with reference to the drawings.
[Example 1]
First, a tantalum valve action metal powder is pressure-molded, and as shown in FIG. 1, an oxide film layer 3 serving as a dielectric is formed on the surface of the anode body 1 on which the anode lead-out wire 2 is planted, and a solid electrolyte ( The capacitor element 7 was formed by sequentially laminating the manganese dioxide layer 4 and the cathode lead layer of the carbon layer 5 and the silver layer 6.

Subsequently, on the entire outer peripheral surface excluding the surface (bottom surface) opposite to the surface where the anode lead-out line is planted and the cathode lead-out portion having substantially the same shape as the cathode shape as shown in FIG. 1 and FIG. An epoxy insulating resin 8 is coated and cured to coat the resin, and the anode lead-out line and its peripheral portion (anode lead-out portion) and the cathode lead-out portion, which are not coated with the resin sheath, are respectively silver-plated 9 and 12, and metal plated Layers 10 and 13 and solder layers 11 and 14 were formed as electrodes to produce a chip-shaped solid electrolytic capacitor.
The ratings were two types of 6.3 V-100 μF and 6.3 V-47 μF, and a product with a reduced profile (product with a reduced product height at the time of mounting) was produced.

[Example 2]
A capacitor element is formed in the same manner as in Example 1, and then all except the bottom surface and the bottom surface as shown in FIGS. 2 and 2B and the cathode lead-out portion having the same shape as the substrate mounting portion of the cathode. A chip-shaped solid electrolytic capacitor was produced in the same manner as in Example 1 except that the outer peripheral surface was coated with an insulating resin.

(Conventional example)
A capacitor element was formed in the same manner as in Example 1, and then a chip-shaped solid electrolytic capacitor was produced in the same manner as in Example 1 except that an insulating resin was coated on the entire outer peripheral surface except the bottom as shown in FIG. did.

  Next, ESR was measured for the examples of the present invention together with the conventional example. Table 1 shows the average value of 100 measurement results.

  As is apparent from Table 1, the ESR values of Examples 1 and 2 according to the present invention were significantly reduced as compared with the conventional example.

  Moreover, it turns out that the deterioration of the ESR value by making the product thinner is reduced in both Examples 1 and 2 as compared with the conventional example.

This is considered to be because the area of the cathode lead-out portion can be enlarged by the present invention, and the efficiency of derivation and introduction of current during charge / discharge is improved.
It can be seen that the effect of ESR reduction is greatest in Example 1 in which the area of the cathode lead-out portion is the largest.

  It should be noted that the shape and size of the cathode lead-out portion that is larger than the conventional one is not limited to the above embodiment, and the bottom surface and the first to fourth surfaces connected to the bottom surface may be substantially the same shape as the cathode.

  The impedance in the high frequency range is affected by the ESL of the product, but since the ESL is affected by the length of the electrical path from the capacitor element to the mounting portion of the electrode, Obviously, the impedance at high frequencies is reduced when expanded to.

  Furthermore, as shown in FIG. 3, regarding the cathode lead-out portion on the mounting surface side, if an exterior resin is present at the edge portion on the cathode side of the capacitor element, the coplanarity (flatness) of the chip-shaped solid electrolytic capacitor becomes more stable. The shape may be such that the exterior resin is present in the edge portion.

  In the examples of the present invention, tantalum was used as the valve action metal powder, but the same effect can be obtained by using niobium.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the chip-shaped solid electrolytic capacitor of Example 1, (a) is the figure of the cathode derivation | leading-out part seen from the cathode side diagonally upper side after insulation resin coating, (b) is the board | substrate mounting surface side after insulation resin coating It is the figure of the cathode derivation | leading-out part seen more. It is sectional drawing of the chip-shaped solid electrolytic capacitor of Example 2 of this invention, (a) is the figure of the cathode derivation | leading-out part seen from the cathode side diagonally upper direction after insulation resin coating, (b) is the downward direction after insulation resin coating It is the figure of the cathode derivation | leading-out part seen more. It is sectional drawing of the chip-shaped solid electrolytic capacitor of the other Example of this invention, (a) is the figure of the cathode derivation | leading-out part seen from the cathode side diagonally upper direction after insulation resin coating, (b) is after insulation resin coating It is a figure of the cathode derivation part seen from the lower part. It is sectional drawing of the chip-shaped solid electrolytic capacitor of a prior art example, (a) is the figure of the cathode derivation | leading-out part seen from the cathode side diagonally upper side after insulation resin coating, (b) is from the board | substrate mounting surface side after insulation resin coating It is the figure of the cathode derivation | leading-out part seen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anode body 2 Anode lead-out line 3 Oxide film layer 4 Conductive layer 5 Carbon layer 6 Silver layer 7 Capacitor element 8 Exterior resin 9 Silver electrode (anode)
10 Metal plating layer (anode)
11 Solder layer (anode)
12 Silver electrode (cathode)
13 Metal plating layer (cathode)
14 Solder layer (cathode)
15 Cathode lead-out part (immediately after insulating resin coating)
16 Insulating resin

Claims (1)

Part of the anode lead-out line and cathode lead-out layer of a capacitor element formed by pressure-molding valve action metal powder and forming an oxide film layer, solid electrolyte layer, and cathode lead-out layer on the surface of the anode body on which the anode lead-out line is planted The outer peripheral surface excluding the cathode lead-out portion provided on the outer surface is covered with an insulating resin, and the anode lead-out line not provided with the resin sheath, the anode lead-out portion composed of the peripheral portion, and the cathode lead-out portion on the surface facing the anode lead-out line In a chip-shaped solid electrolytic capacitor in which one or more conductor layers are formed and used as electrodes,
A chip-shaped solid electrolytic capacitor, wherein the cathode lead-out portion is provided on a surface facing the planting surface of the anode lead-out line of the capacitor element and at a position corresponding to at least the substrate mounting portion of the cathode.

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