JP2570143B2 - Chip type solid electrolytic capacitor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-type solid electrolytic capacitor and a method of manufacturing the same, and more particularly, to a method of forming an anode terminal and a cathode terminal on an exterior of a capacitor element after forming the exterior of the capacitor element and simultaneously forming an anode lead of the capacitor element. And a chip-type solid electrolytic capacitor obtained by being connected to a cathode conductor and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional chip-type solid electrolytic capacitor is formed by connecting external positive and negative leads 14 and 13 to both ends of a capacitor element 3 manufactured by a known technique, and then performing transfer molding or the like. It is assembled with the exterior. However, the chip-type solid electrolytic capacitor of this structure has the exterior resin layer 12A and the positive / negative lead terminal 1A.
The volume efficiency is low because the volume is taken up at the connection portion with 4,13.

[0003] In view of the above, in order to increase the volumetric efficiency and reduce the size of the capacitor, first, the capacitor element is provided with an exterior, and then the anode terminal, which serves as a connection terminal to an external circuit, is provided on the exterior resin. A so-called leadless type chip-type solid electrolytic capacitor having a structure in which a cathode terminal is formed, and both terminals are simultaneously connected to the anode lead and the cathode conductor of the capacitor element when forming both terminals. Or has been proposed.

[0004] For example, Japanese Patent Publication No. 61-31609 (Japanese Patent Application No. 56-159229, hereinafter referred to as the first publication) discloses a conductor layer 1 as shown in the sectional view of FIG.
A chip-type solid electrolytic capacitor having a structure in which a positive / negative terminal having a three-layer structure composed of a plating layer 18 and a solder layer 8 is formed on an exterior resin layer 12B is disclosed. Sun
The cathode terminal is formed on the exterior resin layer 12B on the side of the capacitor and on the end face of the element 3, and is connected to the protruding portion of the anode lead 1 and the cathode conductor of the element at this end face.

Further, Japanese Patent Application Laid-Open No. Hei 4-99011 (Japanese Patent Application No. 2-208507, hereinafter referred to as a second publication) describes the first publication as shown in the sectional view of FIG. The anode terminal has the same structure as that of the chip-type solid electrolytic capacitor described above, and the anode terminal has a two-layer structure including the plating layer 18 and the solder layer 8, and the cathode terminal.
The terminals consist of the conductor layer 17, the plating layer 18, and the solder layer 8.
Disclosed is a three-layer electrolytic capacitor.

In each of the chip-type solid electrolytic capacitors described in the above two publications, the anode lead 1 implanted in the capacitor element 3 further protrudes from the exterior resin layer 12B and projects outside the exterior resin layer. This portion is connected to an anode terminal serving as a connection terminal for an external circuit.
Therefore, from the viewpoint of volumetric efficiency, there is room for further improving the efficiency by improving the protruding portion of the anode lead 1 from the exterior resin layer 12B.

[0007] Japanese Utility Model Application Laid-Open No. 2-137025 (Jpn.
-43732. Hereinafter, referred to as a third publication)
As shown in the cross-sectional view of FIG. 9, there is disclosed a chip-type electrolytic capacitor in which the projecting portion of the anode lead from the exterior resin layer is eliminated to further increase the volumetric efficiency. In the solid electrolytic capacitor described in this publication, the anode lead 1 is cut immediately after the formation of the capacitor element 3 to eliminate a protruding portion from the element end face, and the conductor layer 17, the plating layer 18 and the solder layer 8 By forming an anode terminal having a three-layer structure, the anode lead 15 and the anode terminal are connected.

[0008]

The chip-type solid electrolytic capacitors disclosed in the above three publications have the following problems due to the structure of the electrode terminals.

(1) Since the connection between the anode lead 1 and the anode terminal is made on the surface of the exterior resin layer 12B, the projection length of the anode lead of 0.3 mm to 0.5 mm is required to secure the connection reliability. Although necessary, this protrusion reduces the volumetric efficiency of the capacitor by 7% to 15%.

(2) In order to expose a part of the surface of the cathode conductor layer of the capacitor element 3 from the exterior resin layer, the powder is formed by masking in advance in the step of forming the exterior resin layer by the electrostatic powder coating method. Do not allow the resin to adhere to that area,
Or, it is necessary to remove the powder resin adhered by air blow or the like after painting, so the number of manufacturing steps increases,
Costs rise.

(3) In a capacitor as disclosed in Japanese Utility Model Laid-Open No. 2-137025, the anode lead is cut at an early stage of the process, so that the subsequent process is a single-piece process and high processing accuracy is required. Therefore, the number of steps and the cost are further increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a chip-type solid electrolytic capacitor having high volumetric efficiency, which does not protrude from the outer end surface of the anode lead, at a low cost.

[0013]

According to the present invention, there is provided a chip-type solid electrolytic capacitor comprising an anode body made of a valve action metal having an anode lead extending from one end face, an oxide film of the valve action metal, a solid electrolyte layer and a cathode. A capacitor element formed by forming a conductor layer in this order, and the outer surface of the capacitor element,
The end face of the side from which the anode lead is led out
An exterior resin layer covering through a water-repellent resin layer formed on the surface, an end face of the exterior resin layer on the anode lead lead-out side and
An anode terminal to which the connection terminal with an external circuit is formed on the side end portion continuous to the end face, the said exterior resin layer
The end face on the side opposite to the end face on the anode lead lead-out side and its pair
A chip-type solid electrolytic capacitor including a cathode terminal formed on a side end connected to an end surface on the opposite side and serving as a connection terminal for an external circuit, wherein the anode terminal is at least the capacitor element. The first connection conductor filled in continuous holes in the exterior resin layer formed on the portion including the anode lead lead-out surface is connected to the anode lead, and the cathode terminal is connected to the capacitor. The element is connected to the cathode conductor layer by a second connection conductor filled in continuous holes in the exterior resin layer formed on a portion including a surface opposite to the anode lead lead-out surface of the element. It is characterized by having been done.

The chip-type solid electrolytic capacitor has an oxide film of the valve action metal, a solid electrolyte layer and a cathode conductor layer formed in this order on an anode body made of a valve action metal having an anode lead led out from one surface. Forming a capacitor element by applying a powdered resin onto the entire outer peripheral surface of the capacitor element except for a predetermined portion of the anode lead using an electrostatic powder coating method, and then forming a gelling temperature of the powdered resin. By performing a heat treatment at a lower temperature, a first exterior forming step of forming an exterior resin layer including continuous pores therein, and a portion including the anode lead lead-out surface and the anode lead lead-out surface of the capacitor element. A first electrode terminal forming step of filling the holes in the exterior resin layer on the portion including the opposing surface with a conductor for connection, and performing a heat treatment at a temperature higher than the gelling temperature of the powder resin With this, a second exterior forming step of eliminating and densely forming the voids in a portion of the exterior resin layer other than the portion filled with the connection conductor, and a step of forming the exterior resin layer on the side of the anode lead lead-out surface. Forming an anode terminal comprising at least one or more conductor layers on a portion including the end surface and the end side surface, and a portion including the end surface and the end side surface on the side of the exterior resin layer facing the anode lead lead-out surface; A second electrode terminal forming step of forming a cathode terminal comprising at least one or more conductor layers thereon.

[0015]

Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a sectional view of a first embodiment of the present invention. FIG. 1B shows a second embodiment of the present invention.
It is sectional drawing of the Example of FIG.

Referring to FIG. 1A, the chip-type solid electrolytic capacitor according to the first embodiment of the present invention is characterized in that the anode lead 1 does not protrude from the exterior resin layer (carbon filling portion 5; described later). This is different from the solid electrolytic capacitors described in the first and second publications. Further, the conductor layer 7
The third publication discloses that the positive / negative terminal composed of two layers of the solder layer 8 is connected to the anode lead 1 and the cathode-side conductor of the capacitor element 3 via the carbon filling portion 5, respectively. It is also different from the described solid electrolytic capacitor.

Referring to FIG. 1 (b), the second embodiment of the present invention differs from the first embodiment in that a plating filling portion 11 is used instead of the carbon filling portion 5, and The difference is that the cathode terminal has a single-layer structure of the solder layer 8, but the respective operations are the same as in the first embodiment.

Hereinafter, the manufacturing steps of these embodiments will be described first, starting from the manufacturing steps of the first embodiment. FIG.
FIGS. 3A to 3B are views showing a cross section of the first embodiment of the present invention in the order of manufacturing steps.

First, a water-repellent resin layer 2, a tantalum oxide film layer, a solid electrolyte layer, and a cathode conductor layer (not shown) are formed on a tantalum anode body having an anode lead 1 planted thereon by a conventionally known method. ) Are sequentially formed to obtain a capacitor element 3 as shown in FIG.

Next, as shown in FIG. 2B, an epoxy powder resin 4 mesh-cut to 50 to 200 μm is coated on the entire outer peripheral surface of the capacitor element 3 by an electrostatic coating method.
After depositing a thickness of ３００300 μm, it is heated in an atmosphere at 85 to 125 ° C. for 60 to 100 seconds. At this time, as shown in the enlarged sectional view in FIG. 2B, the surfaces of the powder resin adhere to each other while maintaining the pores of 5 to 15 μm between the powder particles.

Next, as shown in FIG. 3A, a carbon liquid obtained by diffusing carbon powder mesh-cut to 1 μm or less into water using a surfactant is applied to the periphery of the anode lead 1 and its facing surface ( After coating on the lower end surface of the paper), air-dry at room temperature for 30 to 60 minutes. At this time, the carbon powder enters the pores in the powder resin layer, and the carbon filled portion 5 is formed. Subsequently, when heated in an atmosphere of 150 to 160 ° C. for 30 to 60 minutes, the powder resin gels,
The voids in the portion excluding the carbon filling portion 5 disappear and are completely cured, and the insulating exterior resin layer 6 having a thickness of 100 to 200 μm is formed.

Next, as shown in FIG. 3 (b), the outer peripheral resin layer on the peripheral portion of the anode lead 1 and on the side surface of the end of the element and on the surface opposite to the anode lead lead-out surface and on the side surface of the end portion. Apply silver paste, and in an atmosphere of 150 to 160 ° C, 30 to 60
Heat curing for 10 minutes to form a conductive layer 7 having a thickness of 10 to 30 μm. Then, 10 to 3 is applied by a eutectic solder bath at 240 ° C.
A positive / negative terminal is formed by forming a solder layer 8 having a thickness of 0 μm.

Finally, the anode lead 1 is cut, and FIG.
A chip type tantalum solid electrolytic capacitor of the first embodiment shown in FIG.

Next, a second embodiment will be described. FIGS. 4A to 5B are cross-sectional views showing a cross section of a chip-type solid electrolytic capacitor according to a second embodiment of the present invention in the order of manufacturing steps. First, in the same manner as in the first embodiment, a tantalum capacitor element 3 is obtained by a conventionally known method (FIG. 4).
(A)).

Next, as shown in FIG. 4B, an epoxy liquid resin is applied around the shoulder of the capacitor element 3 to a width of 1 to 1.5 m.
m in a band shape, and in an atmosphere of 120 to 150 ° C for 30 minutes.
Heat it for ~ 60 minutes to completely cure it to form an insulating resin layer 9 having a thickness of 10-20 µm.

Next, as shown in FIG. 5 (a), the epoxy powder resin 4 is adhered in the same manner as in the first embodiment, and is heat-treated to leave the pores between the powder particles and to keep the surfaces together. To adhere.

Next, as shown in FIG. 5 (b), a plating catalyst imparting agent obtained by dissolving a palladium amine compound in butyl acetate is applied to the periphery of the anode lead 1 and the side surface of the end and the surface facing the anode lead lead-out surface. And dried at room temperature for 30 minutes or more, and then electroless nickel plating bath is performed to form a plating layer 10 having a thickness of 5 to 10 μm. Then, similarly to the first embodiment, heating is performed in an atmosphere at 150 to 160 ° C. to eliminate holes in a portion except for the plating layer 10, thereby obtaining 10.
The insulating sheath resin layer 6 having a thickness of 0 to 200 μm is formed.

Then, the eutectic solder bath at 240 ° C.
A solder layer 8 having a thickness of 0 to 30 μm is formed to serve as a positive / negative terminal.

Finally, the anode lead 1 is cut, and FIG.
A chip-type tantalum solid electrolytic capacitor according to the second embodiment shown in FIG.

Table 1 shows a comparison between the volume efficiency and the number of manufacturing steps for each of the chip-type solid electrolytic capacitors according to the first and second embodiments of the present invention and the conventional capacitor. In the table, Conventional Examples 1 to 4 mean the following chip-type solid electrolytic capacitors. Conventional Example 1 A chip-type solid electrolytic capacitor obtained by transfer molding (see FIG. 6). Conventional Example 2 A chip-type solid electrolytic capacitor disclosed in the first publication (see FIG. 7). Conventional Example 3 A chip-type solid electrolytic capacitor disclosed in the second publication (see FIG. 8). Conventional example 4 ... A chip type solid electrolytic capacitor disclosed in the third publication (see FIG. 9).

The numerical values shown in Table 1 are values when both the volume efficiency and the number of manufacturing steps are set to 100 in the conventional example 1.

[0032]

[Table 1]

Referring to Table 1, it can be seen that both the first embodiment and the second embodiment of the present invention have improved volumetric efficiency and reduced the number of manufacturing steps as compared with any of the conventional examples.

[0034]

As described above, according to the present invention, since the connection between the anode lead and the anode terminal is made within the thickness of the exterior resin layer, no anode lead protrusion is required. Therefore, the size can be reduced, and the volume efficiency is improved.

Further, since a masking step or the like for exposing the cathode extraction portion from the insulating sheath resin layer is not required, the number of manufacturing steps and cost can be reduced.

According to the present invention, a small chip type solid electrolytic capacitor having excellent volume efficiency can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chip type solid electrolytic capacitor according to a first embodiment of the present invention and a chip type solid electrolytic capacitor according to a second embodiment.

FIG. 2 is a view showing a cross section of the chip-type solid electrolytic capacitor according to the first embodiment of the present invention in the order of manufacturing steps.

FIG. 3 is a diagram showing a cross section of the chip-type solid electrolytic capacitor according to the first embodiment of the present invention in the order of manufacturing steps, and FIG.
FIG. 7 is a view related to the steps after the step shown in FIG.

FIG. 4 is a diagram showing a cross section of a chip-type solid electrolytic capacitor according to a second embodiment of the present invention in the order of manufacturing steps.

FIG. 5 is a diagram showing a cross section of a chip-type solid electrolytic capacitor according to a second embodiment of the present invention in the order of manufacturing steps, and FIG.
FIG. 7 is a view related to the steps after the step shown in FIG.

FIG. 6 is a cross-sectional view of a conventional chip-type solid electrolytic capacitor having an exterior formed by transfer molding.

FIG. 7 is a sectional view showing the structure of an example of a conventional leadless type chip solid electrolytic capacitor.

FIG. 8 is a cross-sectional view showing the structure of another example of a conventional lead-type chip-type solid electrolytic capacitor.

FIG. 9 is a sectional view showing the structure of still another example of the conventional lead-type chip solid electrolytic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode lead 2 Water-repellent resin layer 3 Capacitor element 4 Epoxy powder resin 5 Carbon filling part 6,12A, 12B Outer resin layer 7,17 Conductor layer 8 Solder layer 9 Insulating resin layer 10,18 Plating layer 11 Plating filling part 13 External cathode lead 14 External anode lead

Claims (4)

(57) [Claims] 1. A capacitor element comprising an anode body made of a valve action metal having an anode lead led out from one end face, on which an oxide film of the valve action metal, a solid electrolyte layer and a cathode conductor layer are formed in this order, The outer surface of the capacitor element,
The end face of the side from which the anode lead is led out
An exterior resin layer covering through a water-repellent resin layer formed on the surface, an end face of the exterior resin layer on the anode lead lead-out side and
An anode terminal to which the connection terminal with an external circuit is formed on the side end portion continuous to the end face, the said exterior resin layer
The end face on the side opposite to the end face on the anode lead lead-out side and its pair
A chip-type solid electrolytic capacitor including a cathode terminal formed on a side end connected to an end surface on the opposite side and serving as a connection terminal for an external circuit, wherein the anode terminal is at least the capacitor element. A first connection conductor filled in continuous holes in the exterior resin layer formed on a portion including the anode lead lead-out surface, the first connection conductor being connected to the anode lead, and the cathode terminal being connected to the capacitor The element is connected to the cathode conductor layer by a second connection conductor filled in continuous holes in the exterior resin layer formed on a portion including a surface opposite to the anode lead lead-out surface of the element. A chip-type solid electrolytic capacitor characterized in that: 2. The solid electrolytic capacitor according to claim 1, wherein said valve metal is tantalum. 3. The chip-type solid electrolytic capacitor according to claim 1, wherein the first connection conductor and the second connection conductor are one of conductive fine powder and metal plating. A chip-type solid electrolytic capacitor characterized by the following. 4. An anode body made of a valve action metal having an anode lead led out from one surface, an oxide film of the valve action metal,
Forming a capacitor element by forming a solid electrolyte layer and a cathode conductor layer in this order; and forming a powder resin on the entire outer peripheral surface of the capacitor element except for a predetermined portion of the anode lead using an electrostatic powder coating method. And then heat-treating at a temperature lower than the gelling temperature of the powdered resin to form a packaged resin layer containing continuous pores therein, and the anode of the capacitor element A first electrode terminal forming step of filling a connection conductor into the hole in the exterior resin layer on a portion including a lead lead-out surface and a portion including a surface facing the anode lead lead-out surface; A heat treatment at a temperature higher than the gelling temperature of the resin, a second exterior formation step of eliminating and densely forming the voids in the portion of the exterior resin layer other than the portion filled with the connection conductor; Exterior resin An anode terminal comprising at least one or more conductor layers is formed on a portion including an end surface and an end side surface of the layer on the side of the anode lead lead-out surface, and a surface side of the exterior resin layer facing the anode lead lead-out surface. A second electrode terminal forming step of forming a cathode terminal composed of at least one or more conductive layers on a portion including the end face and the end side face of the second electrode terminal. Manufacturing method of chip type solid electrolytic capacitor.