JPH08130162A - Manufacture of chip-type solid electrolytic capacitor - Google Patents

Abstract

PURPOSE: To expose a portion which is to be a cathode easily and securely while an outer covering is formed of molding resin. CONSTITUTION: A capacitor element 10 is covered with an outer covering 4 formed of molding resin while an anode lead wire 5 is exposed. The part of the molding resin corresponding to a portion to be the cathode terminal of the capacitor has a cut part 4b which is so formed as to border that part. In a process afterwards, the part bordered by the cut part 4b is peeled off and the portion of a first conductive layer 3 which is the cathode part of the capacitor element 10 is exposed. A conductive layer is formed on that exposed part and used as a cathode terminal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small size and large capacity chip type solid electrolytic capacitor suitable for high density mounting.

[0002]

2. Description of the Related Art Conventional chip-type solid electrolytic capacitors are:
As shown in FIG. 6, a dielectric oxide film (not shown), a manganese dioxide layer 102 as a cathode material, and a carbon layer are formed on the surface of the porous metal body 101 in which a part of the anode lead wire 105 is embedded. First conductive resin layer 1 such as silver paint
03 are sequentially formed to serve as capacitor elements. A liquid resin is coated on this capacitor element, or powder resin is applied by electrostatic coating or a fluid immersion method to form an outer casing 104 on a portion excluding a portion serving as an anode portion and a portion serving as a cathode portion. The cathode terminal has a structure formed by the second conductive resin layer 106 such as silver paste and nickel plating layer and the solder layer 107, respectively.

In this structure, the anode lead wire 105 projects at the anode terminal, and the exterior 104 is made of liquid or powder resin, so that the shape of the capacitor is unstable, the dimensional accuracy is poor, and the circuit board is poor. The mounting reliability was low during automatic mounting.

In order to solve this drawback, a chip-type solid electrolytic capacitor using a molding resin having good shape stability as the exterior 104 has been proposed. In this case, the problem is how to expose the part that will become the cathode terminal from the molding resin.For example, when molding the exterior, make the bottom of the capacitor element, which becomes the cathode terminal, adhere to the molding die. A method has been proposed in which the outer surface of the mold is applied in such a state that the exposed part is exposed (JP-A-56-7).
426). Also, after covering the entire capacitor element with a mold resin, the positive and negative electrode parts are irradiated with a laser beam to locally decompose and evaporate the mold resin,
A method of exposing the anode part and the cathode part of the device has also been proposed (see Japanese Patent Application Laid-Open No. 1-246814).

[0005]

However, when the exterior is made of the molding resin, the conventional method described above has the following problems.

In the one disclosed in Japanese Unexamined Patent Publication No. 56-7426 in which the bottom of the capacitor element is brought into close contact with the molding die to form the exposed portion, the molding resin is used to form the bottom of the capacitor element and the molding die. It was difficult to reliably expose the bottom part of the capacitor element because it easily entered the contact area.

Further, in the one disclosed in JP-A-1-246814, in which the anode part and the cathode part of the capacitor element are exposed by irradiating a laser beam to decompose and evaporate a part of the mold resin, a laser beam is used. However, there is a problem that it is difficult to remove only the mold resin locally, and that the capacitor element itself may be thermally damaged by the irradiation of the laser beam.

Therefore, the present invention provides a method for manufacturing a chip-type solid electrolytic capacitor which has a high productivity while allowing a portion serving as a cathode terminal to be easily and surely exposed while forming an exterior with a mold resin. To aim.

[0009]

In order to achieve the above object, a method of manufacturing a chip type solid electrolytic capacitor according to the present invention comprises an exterior of a capacitor element having an anode lead wire and a cathode portion,
In the method for manufacturing a chip-type solid electrolytic capacitor, the anode lead wire and the cathode portion are formed of exposed mold resin, and conductive layers are formed on the exposed portions to form an anode terminal and a cathode terminal, respectively. When the exterior is formed, only the anode lead wire is exposed, and the molding resin is formed so as to cover the capacitor element so as to form a notch that borders a portion of the cathode portion that serves as the cathode terminal. Is molded, and a part of the molded mold resin surrounded by the notch is mechanically removed to expose a part of the cathode part of the capacitor element.

Further, the portion of the anode lead wire exposed from the mold resin is processed into a flat shape, the mold resin is molded, and then the anode lead wire is bent along the end face of the mold resin. A conductive layer is formed to serve as an anode terminal, or a protrusion for gripping is integrally provided in a portion surrounded by the cutout of the mold resin during molding of the mold resin, or surrounded by the cutout of the mold resin. When removing the portion to be removed, a solution having an erosive property to the mold resin may be poured into the notch.

[0011]

In the method of manufacturing a chip type solid electrolytic capacitor of the present invention configured as described above, since the exterior of the capacitor element is made of the mold resin, a chip type solid electrolytic capacitor having a stable shape and a high external dimension accuracy can be obtained. can get.
In particular, when forming the cathode terminal, the cathode portion of the capacitor element is once covered with the mold resin, and the portion that will become the cathode terminal is removed in a later step. As described above, since the notch is formed and the portion surrounded by the notch is mechanically removed, the portion that becomes the cathode terminal is exposed easily and reliably.

Further, in forming the anode terminal, the anode lead wire is processed into a flat shape and then bent, so that the anode terminal is hardly affected by the shape of the anode lead wire and has a substantially flat shape. The electrolytic capacitor has higher external dimension accuracy.

Further, by providing a knob projection in a portion surrounded by the cutout of the mold resin, when removing the portion surrounded by the cutout, by pulling or swinging by holding the projection, The part surrounded by the notch is easily removed.

Further, by pouring a solution having corrosiveness to the mold resin into the notch, the notch portion is corroded by the solution, so that the portion surrounded by the notch is removed with a smaller force.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of a chip type solid electrolytic capacitor obtained in a first embodiment of the method for manufacturing a chip type solid electrolytic capacitor of the present invention.

As shown in FIG. 1, a part of the anode lead wire 5 is embedded in the porous metal body 1 having a dielectric oxide film (not shown) formed on the surface thereof. A manganese dioxide layer 2 is formed as a cathode material on the surface of the dielectric oxide film, and a first conductive resin layer 3 is further formed on the surface thereof to form a cathode portion. The porous metal body 1, the manganese dioxide layer 1, the first conductive resin layer 3, and the anode lead wire 5 form a capacitor element 10.

Capacitor element 10 is sealed by an outer casing 4 made of a molding resin except for the portions serving as anode lead wire 5 and cathode terminal 9. The molding resin itself has a structure in which a part of the anode lead-out wire 5 is exposed to seal the entire capacitor element 10 in the as-molded state, but in the part which becomes the cathode terminal 9, the part is bordered. Such a notch (not shown in FIG. 1), and the portion surrounded by the notch is removed after molding the outer casing 4,
As a result, the first conductive resin layer 3 is exposed from the exterior 4. Then, the second conductive resin layer 6 and the solder layer 7 are sequentially formed as a conductive layer so as to fill the exposed portion, and the cathode terminal 9 is configured.

On the other hand, in the portion which becomes the anode terminal 8,
The portion is formed in a concave shape, and the anode lead wire 5 is bent so as to be housed in the concave portion 4a. The anode lead wire 5 is preliminarily processed into a flat shape from the bent portion, so that the anode lead wire 5 is completely housed in the recess 4a of the outer package 4. Then, the second conductive resin layer 6 and the solder layer 7 are sequentially formed as a conductive layer so as to fill the concave portion 4a of the outer package 4, thereby forming the anode terminal 8.

Next, the manufacturing process of the chip type solid electrolytic capacitor of this embodiment will be described.

First, as shown in FIG. 2, a part of a metal wire such as tantalum, which also has a valve action, to be the anode lead wire 5 is embedded in a metal powder having a valve action, such as tantalum, niobium, and aluminum. The metal powder is pressed into a uniform shape. At this time, crushing is performed near the embedded portion of the anode lead wire 5 to form a flat crushed portion 5a. Then, the metal powder pressed into a uniform shape is
Vacuum sintering is performed at 00 to 2000 ° C., whereby a porous metal body 1 is obtained.

Then, as conventionally known, a dielectric oxide film is formed on the surface of the porous metal body 1 by anodic oxidation. Porous metal body 1 having a dielectric oxide film formed thereon
A manganese dioxide layer 2 is formed inside and around the porous metal body 1 by impregnating it with a manganese nitrate solution and thermally decomposing it. Further, the first conductive resin layer 3 is formed thereon, and the capacitor element 10 is obtained.

The capacitor element 1 thus obtained
The outer case 4 is made of mold resin. As shown in FIGS. 3 and 4, the outer package 4 has a recess 4a in which the crushed portion 5a of the anode lead wire 5 is housed, as shown in FIGS. Also, the cathode terminal 9
A notch 4b that substantially reaches the first conductive resin layer 3 is formed in the portion to be the edge. In order to form the cutout 4b, a molding die (not shown) has a protrusion corresponding to the cutout 4b, but in order to prevent stress from being applied to the capacitor element 10 when the exterior 4 is formed. In addition, the tip of the protrusion of the mold may be covered with an elastic resin. In this case, as the elastic resin, it is desirable to use a resin having a high releasing effect, such as Teflon resin, in order to avoid the close contact with the molding resin that will be the exterior 4. Further, a portion of the outer package 4 surrounded by the notch 4b is formed with a withdrawing protrusion 4c for facilitating the peeling of this portion in a later step.

After the exterior 4 is applied, the anode terminal 8 and the cathode terminal 9 are formed. In the portion to be the anode terminal 8, the crushed portion 5a of the anode lead wire 5 is sandblasted to remove the dielectric oxide film on the surface. afterwards,
The anode lead wire 5 is crushed, cut at an appropriate position in the processed portion 5a, further bent, and housed in the recess 4a of the exterior 4.

On the other hand, in the portion which becomes the cathode terminal 9,
A pulling force is applied from the outside to the pull-out projection 4c of the outer casing 4, or the pull-out projection 4c is swung. Then, since the strength of the portion where the notch 4b is formed is weakened in the outer package 4, the portion surrounded by the notch 4b is mechanically peeled off, and the first conductive resin layer 3 is exposed.
When the portion surrounded by the notch 4b is peeled off, if a solution having the corrosiveness of the mold resin forming the exterior 4 is poured into the notch 4b, the portion surrounded by the notch 4b can be easily taken off. It is profitable. An epoxy resin is generally used for the outer package 4, and a solution that corrodes the epoxy resin is a strongly acidic solution.

Then, the concave portion 4 in which the anode lead wire 5 is housed
A second conductive resin layer 6 having solderability is applied to the exposed portions of a and the first conductive resin layer 3, and a solder layer 7 is further formed thereon. As a result, the anode terminal 8 and the cathode terminal 9 are formed.

In the chip-type solid electrolytic capacitor obtained as described above, since the exterior 4 is made of the molding resin having good shape stability, the volume of the capacitor element 10 in the volume of the capacitor is as high as about 40%. In addition to achieving efficiency and miniaturization, the external dimension accuracy is high and the mounting reliability during automatic mounting on a circuit board is high.
In particular, since the capacitor element 10 is exposed at the portion to be the cathode terminal 9 by covering the entire capacitor element 10 with the molding resin and then mechanically peeling off the predetermined portion, the capacitor element 10 is molded when the exterior 4 is molded. The wraparound of the resin that occurs when 10 is exposed by being brought into close contact with the mold,
The first conductive resin 3 can be exposed more easily and surely than in the conventional technique without heat damage or the like that occurs when exposed by irradiating a laser beam. Further, since the flattened shape is formed by forming the crushed portion 5a on the anode lead-out wire 5, the surface shape of the anode terminal 8 is a substantially flat shape with no steps or irregularities.

(Second Embodiment) FIG. 5 is a sectional view of a chip type solid electrolytic capacitor obtained in a second embodiment of the method for manufacturing a chip type solid electrolytic capacitor of the present invention. In this embodiment, in order to increase the bonding area of the anode terminal 28 and the cathode terminal 29 and improve the reliability of mounting when mounted on the circuit board, the anode terminal 28 and the cathode terminal 29 are respectively provided on the entire end surface of the capacitor. It has been provided.

The capacitor element 30 has an exterior 24 made of a molding resin except for the anode lead wire 25 and the right end surface in the figure.
It is sealed by. The molding resin itself has a structure in which a part of the anode lead-out wire 25 is exposed and the entire capacitor element 30 is sealed in the as-molded state, but a notch (that cuts off the portion that becomes the cathode terminal 29) ( (Not shown)
The portion surrounded by the notch is removed in a later step, so that the first conductive resin layer 23 is exposed. On the other hand, the portion that becomes the anode terminal 28, that is, the left end surface in the drawing has a flat shape, and the portion of the anode lead wire 25 that projects from the outer casing 24 is bent.

Then, the second conductive resin 26 and the solder layer 27 are formed on both end faces of the capacitor element 30 having the outer package 24, whereby the anode terminal 28 and the cathode terminal 29 are formed on the end faces. A chip type solid electrolytic capacitor is obtained. Other configurations and manufacturing steps are first
The description is omitted because it is the same as the embodiment.

In each of the above-described embodiments, the first conductive resin layers 3 and 23 and the second conductive resin layers 6 and 26 are provided, but instead of these, solder, nickel plating, or the like is used. A configuration in which these metal layers are provided on the metal layer or the conductive resin layer may be used.

[0032]

As described above, according to the method of manufacturing a chip type solid electrolytic capacitor of the present invention, since the exterior of the capacitor element is made of the molding resin, the shape is stable and the external dimension accuracy is high. Capacitor can be obtained. In particular, when forming the cathode terminal, once cover the cathode part of the capacitor element with a mold resin in which a notch is formed that borders the part where the cathode terminal is formed, and in a later step, the part surrounded by the notch. Since it is mechanically removed, the portion to be the cathode terminal can be exposed easily and reliably. As a result, the yield is improved and the productivity of the capacitor can be improved.

Further, when forming the anode terminal, the anode lead wire is processed into a flat shape and bent, so that the shape of the anode terminal becomes stable and the accuracy of the external dimension can be further improved.

Further, by providing a knob projection in the portion surrounded by the cutout of the mold resin, when removing the portion surrounded by the cutout, the portion surrounded by the cutout can be easily removed. .

In addition, by pouring a solution having corrosiveness against the mold resin into the notch, the portion surrounded by the notch can be removed with a smaller force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a chip-type solid electrolytic capacitor obtained in a first embodiment of a method for manufacturing a chip-type solid electrolytic capacitor of the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the chip-type solid electrolytic capacitor shown in FIG. 1, and is a perspective view at a stage when a porous metal body is obtained.

FIG. 3 is a diagram for explaining a manufacturing process of the chip-type solid electrolytic capacitor shown in FIG. 1, and is a cross-sectional view at a stage when an exterior is molded with a mold resin.

FIG. 4 is a diagram for explaining a manufacturing process of the chip-type solid electrolytic capacitor shown in FIG. 1, at the same stage as in FIG.
It is the perspective view seen from the bottom side.

FIG. 5 is a cross-sectional view of a chip type solid electrolytic capacitor obtained in a second embodiment of the method for manufacturing a chip type solid electrolytic capacitor of the present invention.

FIG. 6 is a cross-sectional view of a conventional chip type solid electrolytic capacitor.

[Explanation of symbols]

 1 Porous Metal Body 2 Manganese Dioxide Layer 3, 23 First Conductive Resin Layer 4, 24 Exterior 4a Recess 4b Notch 4c Extraction Protrusion 5, 25 Anode Lead-out Wire 5a Crush Processed Part 6, 26 Second Conductivity Resin layer 7, 27 Solder layer 8, 28 Anode terminal 9, 29 Cathode terminal 10, 30 Capacitor element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01G 9/08 C

Claims (4)

[Claims] 1. An exterior of a capacitor element having an anode lead wire and a cathode portion is formed by a mold resin exposing a part of the anode lead wire and a cathode portion, and a conductive layer is formed on the exposed portion. Then, respectively as the anode terminal and the cathode terminal, in the method of manufacturing a chip-type solid electrolytic capacitor, when forming the exterior, only the anode lead wire is exposed,
Further, the mold resin is molded so as to cover the capacitor element so as to form a notch that borders a portion of the cathode portion that becomes the cathode terminal, and the molded resin is surrounded by the notch. A method for manufacturing a chip-type solid electrolytic capacitor, characterized in that a part of the cathode part of the capacitor element is exposed by mechanically removing the part to be covered. 2. A portion of the anode lead wire exposed from the mold resin is processed into a flat shape, the mold resin is molded, and then the anode lead wire is bent along an end face of the mold resin. The method for manufacturing a chip solid electrolytic capacitor according to claim 1, wherein a conductive layer is formed to serve as an anode terminal. 3. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 1, wherein a knob projection is integrally provided on a portion of the mold resin surrounded by the notch when the mold resin is molded. . 4. The chip mold according to claim 1, 2 or 3, wherein a solution having an erosion property with respect to the mold resin is poured into the notch when removing a portion of the mold resin surrounded by the notch. Manufacturing method of solid electrolytic capacitor.