JP2003109849A - Method for manufacturing chip type solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost of a chip type solid electrolytic capacitor. SOLUTION: In a method for manufacturing the chip type solid electrolytic capacitor 1 the capacitor comprises a capacitor element 2 and an enclosure resin 3 covering the capacitor element 2, and is formed so that one part of each terminal of an anode terminal 5 and a cathode terminal 7 connected to an anode lead-out line 4 and a cathode layer of the capacitor element 2, respectively, is exposed at least at a mounting surface of the chip type solid electrolytic capacitor. A lead frame 11 is formed with an alloy 42, and a rising part 15 is formed to extend to the anode terminal 5. The rising part 15 is not given silver plating 12 and the cathode terminal 6 is given silver plating. A side of the anode lead-out line 4 is made to come in contact with the rising part 15 and by laser irradiation from the rising part 15 side one part of the anode terminal 6 is melted and welded to the anode lead-out line 4. Because the reflectivity of a laser beam is low at the rising part 15, the energy of the laser beam can be efficiently used for melting the rising part 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a chip type solid electrolytic capacitor which can be used for high density surface mounting mounted on various electronic devices.

[0002]

2. Description of the Related Art As a conventionally known chip-type solid electrolytic capacitor, for example, a practical solid-state capacitor 48-8 shown in FIG.
There is one such as that described in 8942. This chip-type solid electrolytic capacitor 51 has an oxide film which becomes a dielectric by anodization formed on the surface of an anode body obtained by molding and sintering valve metal powder such as tantalum. A capacitor element 52 obtained by forming a solid electrolyte layer of manganese dioxide or the like on a cathode layer made of carbon or silver paste, and attaching the capacitor element 52 to a lead frame having an anode lead 55 and a cathode lead 56. Has been done.

The lead frame used in these chip-type solid electrolytic capacitors 51 is, for example, Shoukai 62-89.
No. 126 has a structure as shown in FIG. 5 or FIG. 6 and has a main body of a capacitor element in which an anode lead wire derived from the capacitor element is welded to an anode lead frame and the cathode layer is provided on the outer periphery thereof. Part is attached to the lead frame of the cathode by soldering, etc., the capacitor element is resin-sealed by transfer molding with epoxy resin, etc., and the external lead formed by cutting the lead frame is bent along the exterior to form a chip-type solid. An electrolytic capacitor is configured.

However, such a chip-type solid electrolytic capacitor 51 has an anode lead wire 54 and an anode lead 55.
Since the welded portion of and is also covered with the resin 53, the volume occupied by the capacitor element 52 with respect to the size of the entire capacitor is small, and it is sufficient for the demand for a capacitor having a small size and large capacity. It was not something I could handle.

For this reason, Japanese Patent Laid-Open No. 55-86111 in FIG.
Chip type solid electrolytic capacitor 61 having a structure as shown in FIG.
It has been known. This chip type solid electrolytic capacitor 61
Is a structure in which the external electrodes 65 and 66 are provided on the mounting surface of the capacitor, and the external electrodes 65 and 66 and the anode lead wire 64 of the capacitor element 62 are connected via a conductive auxiliary lead wire 69.

[0006]

In the chip type solid electrolytic capacitor having the above structure, the anode lead wire and the anode terminal are joined by resistance welding such as spot welding. By the way, when joining by the resistance welding method, welding is performed at the contact portion between the anode terminal and the anode lead wire. However, there are variations in the lead-out position of the anode lead wire in the capacitor element, and the capacitor element is placed on the lead frame. Depending on the mounting position, the contact position between the anode lead wire and the anode terminal may differ, and the welding position may fluctuate. If the anode terminal and the anode lead wire are not in contact with each other, problems such as welding may not occur.

Therefore, the Applicant pays attention to the above-mentioned problems, and provides a standing portion at a portion which becomes an anode terminal of a lead frame which becomes the anode terminal and the cathode terminal, and mounts a capacitor element on the lead frame. After bringing the side surfaces of the standing portion and the anode lead wire close to each other, by laser irradiation from the side of the standing portion, it is found that a part of the anode terminal can be melted and joined to the anode lead wire to solve the problem. I filed an application earlier (Japanese Patent Application No. 2000-34682)
3).

However, in the chip type solid electrolytic capacitor, when the capacitor element is mounted on the lead frame, the electric resistance value between the lead frame and the capacitor element is reduced, and the chip type solid electrolytic capacitor is further reduced in ES.
In order to achieve R, the lead frame may be plated to improve the bondability between the lead frame and the conductive adhesive material, thereby reducing the contact resistance between the capacitor element and the cathode layer. .

The use of such a plated lead frame is preferable because the contact resistance between the cathode layer of the capacitor element and the lead frame can be reduced and the joint strength can be increased, but the lead frame and the capacitor are preferable. It has been found that there is a problem in joining the anode lead wire of the element by laser welding.

That is, when the lead frame is plated, the rate of reflection of the irradiated laser increases, the energy of the laser does not contribute to melting of the lead frame, and the energy loss increases. there were. In particular, as a material for the lead frame, 42 alloy, which is an iron-nickel alloy, is widely used because it is cheap and easy to process. The lead frame is plated with silver, tin, nickel or the like. In many cases, silver plating, tin plating, nickel plating, etc. have higher laser reflectance than 42 alloy, and there is a large energy loss when welding the anode lead wire and anode terminal, increasing the manufacturing cost. There was a problem that it would end up. Further, there is a possibility that the reflected laser may adversely affect the capacitor element and the like around the irradiation part.

The present invention is intended to solve the above problems, and an object thereof is to provide a method for manufacturing a chip-type solid electrolytic capacitor in which the anode lead wire and the anode terminal are securely and efficiently connected. I am trying.

[0012]

According to the present invention, a dielectric oxide film is formed on the surface of an anode body in which a rod-shaped anode lead wire is embedded, and a solid electrolyte layer and a cathode layer are successively laminated to form a dielectric oxide film. A capacitor element whose outer periphery is the cathode layer,
An outer resin covering the capacitor element, and an anode terminal and a cathode terminal respectively connected to the anode lead wire and the cathode layer of the capacitor element, at least a part of each terminal being at least a mounting surface of the chip type solid electrolytic capacitor. In a method of manufacturing a chip-type solid electrolytic capacitor formed so as to be exposed, a standing portion is formed on an anode terminal of a lead frame which is an iron-nickel alloy and whose surface is plated and the cathode terminal. With the provision of at least the rising portion is a non-plated portion, the capacitor element is mounted on the lead frame to bring the side surfaces of the rising portion and the anode lead wire close to each other, and then by laser irradiation from the standing portion side, It is characterized in that a part of the anode terminal is melted and joined to the anode lead wire.

Even when the iron-nickel alloy is used as the material of the lead frame and the lead frame is plated, the portion where the laser beam is radiated by forming the anode terminal upright portion as the non-plated portion as in the present invention. Means that the iron-nickel alloy is exposed, and the reflectance of the laser when irradiated with the laser is small. Therefore, the energy loss of the laser is reduced in welding the standing portion and the anode lead wire.

In the above-described method for manufacturing a chip type solid electrolytic capacitor, it is preferable that the standing portion and the side surface of the anode lead wire are brought into contact with each other when the capacitor element is mounted on the lead frame.

According to the manufacturing method of the present invention, when the capacitor element is mounted on the lead frame provided with the rising portion,
Since the standing portion is brought into contact with the anode lead wire of the capacitor element, the standing portion can be used as a positioning reference for the capacitor element. Therefore, it is possible to keep the number of laser-welded portions constant and to obtain reliable joining.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (Embodiment) FIG. 1 is a perspective view showing a structure of a chip type solid electrolytic capacitor of the present embodiment, FIG. 2 is a sectional view showing a chip type solid electrolytic capacitor of the present embodiment, and FIG. The figure seen from the figure, (b) is the figure seen from the side.

Chip type solid electrolytic capacitor 1 of this embodiment
As shown in FIG. 1, a capacitor element 2, an anode terminal 5 to which an anode lead wire 4 led out from the side surface of the capacitor element 2 is connected by welding, and the anode terminal 5 and the capacitor element 2 are connected to each other. The capacitor element 2 is provided on the opposite sides of the capacitor element 2.
The cathode terminal 6 which is arranged below the outer peripheral portion of the capacitor element 2 and is electrically and mechanically joined to the lower surface of the outer peripheral portion of the capacitor element 2 by the conductive adhesive 10, and the exposed portions of the anode terminal 5 and the cathode terminal 6. The part to be removed is mainly composed of an exterior resin 3 covering the capacitor element 2 so as to cover it.

The capacitor element 2 is an element conventionally used as a solid electrolytic capacitor element, for example, an anode body obtained by molding and sintering a valve metal powder such as tantalum. The rod-shaped anode lead wire 4 made of is embedded. Then, it is obtained by forming an oxide film which becomes a dielectric on the surface of the anode body by anodization and laminating a solid electrolyte layer such as manganese dioxide and a cathode layer made of carbon or silver paste on the anode body. A capacitor element or the like can be preferably used. It is also possible to use a polymer electrolyte such as polypyrrole as the solid electrolyte.

The anode terminal 5 used in this embodiment is
The standing portion 15 is bent in a V shape so as to be continuous from the exposed portion of the anode terminal 5. And the standing portion 15
One side surface comes into contact with the side surface of the anode lead wire 4.
Since the anode terminal 5 is arranged on the lower surface of the capacitor element 2, when the lower surface of the capacitor element 2 and the anode terminal 5 come into contact with each other, the anode terminal 5 is interposed via the cathode layer formed on the surface of the capacitor element 2. And the cathode terminal 6 are short-circuited, the insulating resin 9 is provided on the upper surface of the anode terminal 5 so that the insulating resin 9 is interposed between the capacitor element 2 and the lower surface thereof.

The chip type solid electrolytic capacitor 1 of this embodiment will be described below along with its manufacturing process. First, in this embodiment, the anode terminal 5 and the cathode terminal 6 have a shape as shown in FIG. 2, and are formed by a lead frame 11 on which a plurality of capacitor elements 2 can be mounted.
The lead frame 11 has a shape as shown in FIG. 3, and an upright portion 15 is formed in a portion to be an anode terminal by pressing or bending a plate-shaped metal plate. The lead frame in this FIG. 3 shows only the peripheral portion of the mounted capacitor element, and the lead frame actually used is connected to the front, rear, left and right with the lead frame shown in FIG. 3 as one unit. I am using what I made. The height of the standing portion 15 is higher than the position of the anode lead wire of the capacitor element when the capacitor element described later is mounted on the lead frame. As a method of forming the standing portion 15, the lead frame 1
It is preferable to form part of 1 by bending, since the standing portion can be formed at the same time as the step of pressing the lead frame from the plate-shaped metal, and the working process is simplified.

The material of the lead frame 11 is an iron alloy (iron-containing 42% nickel).
42 alloy which is a nickel alloy) is used. The lead frame 11 is plated with silver 12. The silver plating is formed only on the portion of the lead frame 11 that will be the cathode terminal 6. In order to partially plate the lead frame 11 as described above, it is possible to form it by a method of performing partial plating or a method of removing the necessary portion after performing the entire surface plating. Further, the silver plating 12 may be applied before forming the rising portions 15 on the lead frame 11, or may be applied after forming the rising portions 15.

In addition, the silver plated portion 12 may be plated on any other portion as long as the upright portion 15 is not plated with silver, but since silver plating is expensive, the lead is used. It is preferable to plate only the portion of the frame 11 to be the cathode terminal 6. Further, as the type of plating, other than silver plating, tin plating, nickel plating, or the like can be selected.

Then, as shown in FIG. 4A, a coating material is applied to the upper surface of the portion of the lead frame 11 to be the anode terminal 5 and dried to form the insulating resin 9. In the present embodiment, as a method of applying these paints, an ink jet nozzle (not shown) is used to apply the paint to the relevant portion of the lead frame 11 so that the thickness of the insulating resin 9 is a thickness that provides sufficient insulation. However, the present invention is not limited to this, and any method can be used as a method for forming these insulating resins 9.

In the coating and drying by the ink jet nozzle, the coating and drying are repeated a plurality of times so that a good insulating resin layer without pinholes can be formed.

Further, as the insulating resin 9, a UV-curable resin is used in the present embodiment because a coating film having a relatively large thickness can be easily obtained from the height of the solid content of the resin as well as the efficiency of the drying process. Although used, the invention is not so limited.

After the insulating resin 9 is formed, as shown in FIG.
As shown in FIG. 4, a conductive adhesive 7 such as a silver paste is applied and formed on the upper surface of the portion to be the cathode terminal 6, and after the application, the conductive adhesive 7 is formed as shown in FIG.
The capacitor element 2 is mounted as shown in (c). The upper surface of the portion of the lead frame 11 that becomes the cathode terminal 6 is plated with silver, and has good adhesion with the conductive adhesive 7. Therefore, the contact resistance at the interface between the silver plating layer and the conductive adhesive 7 layer is reduced, and the low ESR of the solid electrolytic capacitor is reduced.
Can be realized.

Capacitor element 2 for lead frame 11
When mounting, the upright portion 15 serves as a reference for positioning the capacitor element 2 with respect to the lead frame 11. Therefore, by making the formation shape of the rising portion 15 on the lead frame 11 uniform, it becomes easy to always mount the capacitor element 2 at the same position. in this way,
The capacitor element 2 is attached to the lead frame 1 so that the anode lead wire 4 of the capacitor element 2 is brought into contact with the upright portion 15.
1 mounted on the lead frame 1 of the capacitor element 2
It is preferable because it can be easily positioned with respect to No. 1. However, the upright portion 15 and the anode lead wire 4 need only be brought close to each other by the laser welding described later so that the anode lead wire 4 and the lead frame 11 can be joined. But good.

If the standing portion 15 is in contact with the side surface of the anode lead wire 4, the joint area between the anode lead wire 3 and the anode terminal 5 can be increased, and at the same time, the completed chip die can be formed. The length of the solid electrolytic capacitor body can be reduced.

As the conductive adhesive 7, since the cathode layer made of carbon or silver paste is exposed on the lower surface of the capacitor element 2 to be connected, as described above, the adhesiveness to these cathode layers is taken into consideration. Therefore, the silver-based conductive adhesive 7 that is usually used for mounting ICs and the like is preferably used, but the present invention is not limited to this, and the conductive adhesive 7 may be replaced by solder. Alternatively, a paste or the like may be applied, and after mounting the capacitor element 2, the solder paste may be melted to fix and mount the capacitor element 2. In this case, it is preferable to select a metal that has good adhesion to the conductive adhesive 7 and plate the portion of the lead frame 11 that will become the cathode terminal.

Then, as shown in FIG. 4D, the anode lead wire 4 and the rising portion 15 are connected by laser welding. At this time, the irradiation of the laser 10 is performed from the standing portion 15 side of the anode terminal 6. Since the standing portion 15 is not silver-plated and 42 alloy is exposed, the laser 10
Has a low reflectance. Therefore, the energy of the irradiated laser 10 efficiently contributes to the melting of the standing portion 15, and the energy efficiency is increased. According to the measurement by the inventor, the reflectance of 42 alloy is about 40%, while
The reflectance on the silver-plated surface is 96.4%, similarly 90.1% for copper plating and 5 for tin plating.
It is 4.0% and 72.0% in the case of nickel plating, and it is known that the reflectance of the laser on the surface where 42 alloy is exposed is extremely low.

Further, the irradiation of the laser 10 is performed as shown in FIG.
It is effective to set the incident angle so as to form an angle of 40 degrees or more with respect to the side surface (laser irradiation surface) of the rising portion 15 as shown in FIG.

When a metal is irradiated with a laser, the laser reflects on the metal surface to cause a loss of incident energy, but the incident angle of the laser with respect to the laser irradiation surface is 4
When the angle is 0 ° or more, the rate of reflection on the metal surface is reduced, and the laser energy can be efficiently used for melting the metal.

By irradiating the laser 10 from the upright portion 15 side, the metal forming the upright portion 15 is melted to surround the anode lead wire 4. As a result of this laser welding, the joint area between the upright portion 15 and the anode lead wire 4 is increased, the joint strength is increased, and the contact resistance can be reduced. Further, in the embodiment of the present invention, high purity tantalum is used as the anode lead wire 4, and the lead frame 11
42 alloy is used. The melting point of tantalum is 29
At 96 ° C., the melting point of 42 alloy is about 1450 ° C. Therefore, when laser irradiation was performed from the side of the lead frame 11, the anode lead wire 4 made of tantalum did not melt but was formed of 42 alloy. Only the lead frame 11 melts. As described above, when the lead frame 11 is made of a material having a melting point lower than that of the anode lead wire 4, the shape of the anode lead wire is not deformed, and the welding position and the joint strength are easily controlled, which is preferable.

In order to perform laser irradiation at an angle of 40 degrees or more with respect to the laser irradiation surface of the standing portion 15, the height of the standing portion 15 is set to be higher than the position of the anode lead wire 4 of the capacitor element 2. It should be expensive. With such a shape, laser irradiation can be performed from above or from the side, and the anode terminal or the like does not interfere with laser irradiation. Therefore, the laser irradiation can be performed by setting the incident angle of the laser with respect to the laser irradiation surface to an arbitrary angle of 40 degrees or more.

Further, the conductive adhesive 7 is dried or cured to fix the capacitor element 2.

Next, as shown in FIG. 4 (e), the entire capacitor element and the lead frame 11 are covered with a sealing resin to be the exterior resin 3, and the exterior resin 3 is cured.

As the exterior resin 3, an epoxy resin such as epoxy acrylate, which is a molding resin used in conventional transfer molding, can be preferably used, and at the same time, heat resistance that can withstand solder heat during mounting on a substrate. Any resin having properties and capable of obtaining a liquid state at an appropriate heating state or room temperature can be suitably used.

After the exterior resin 3 has been appropriately cured, a continuous body of the chip type solid electrolytic capacitors is cut out at a predetermined position to obtain individual chip type solid electrolytic capacitors 1.

The present invention has been described above with reference to the drawings. However, the present invention is not limited to the above-mentioned embodiments, and even if there are changes and additions without departing from the spirit of the present invention, Needless to say, it is included in the present invention. For example, as the shape of the anode terminal, as shown in FIGS.
Make a notch in the anode terminal 5 as shown in Fig.
A shape obtained by vertically cutting 5 may be used.

[0040]

According to the first aspect of the present invention, a standing portion is provided on at least the anode terminal of the lead frame which is made of an iron-nickel alloy and whose surface is plated, and the anode terminal of the lead frame which serves as the cathode terminal. The standing portion is a non-plated portion, a capacitor element is mounted on the lead frame to bring the side surfaces of the standing portion and the anode lead-out wire close to each other, and then laser irradiation from the side of the standing portion causes one of the anode terminals to move. Since the portion is melted and joined to the anode lead wire, the reflectance of the laser at the standing portion is low, the laser energy efficiently melts the standing portion, and welding with the anode lead wire can be achieved. Further, it is possible to prevent the reflected laser from adversely affecting surrounding parts such as the capacitor element.

According to the second aspect of the present invention, since the capacitor element is mounted on the lead frame provided with the rising portion, the rising portion can be used as a positioning reference for the capacitor element. Therefore, it is possible to keep the number of laser-welded parts constant and to obtain reliable joining.

[Brief description of drawings]

FIG. 1 is a perspective view showing a chip type solid electrolytic capacitor of the present invention.

FIG. 2 is a cross-sectional view showing the internal structure of the chip-type solid electrolytic capacitor of the present invention, FIG.
(B) is the figure seen from the side surface.

FIG. 3 is a perspective view showing a lead frame used in the present invention.

FIG. 4 is an explanatory view showing a method for manufacturing a chip type solid electrolytic capacitor of the present invention, in which (a) to (e) respectively represent manufacturing steps, the left side of the chain line is a front view, and the right side of the chain line is a side surface. It is a figure from.

FIG. 5 is a sectional view showing another embodiment of the present invention,
(A) is the figure seen from the front, (b) is the figure seen from the side.

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

FIG. 7 is a cross-sectional view showing a conventional chip type solid electrolytic capacitor.

FIG. 8 is a diagram illustrating an irradiation angle of a laser with respect to a standing portion.

[Explanation of symbols]

1 chip type solid electrolytic capacitor 2 Capacitor element 3 Exterior resin 4 Anode lead wire 5 Anode terminal 6 cathode terminal 7 Conductive adhesive 9 Insulating resin 10 laser 12 silver plating 15 Standing part 51 Chip type solid electrolytic capacitor 53 Exterior resin 54 Anode lead wire 55 Anode terminal 56 cathode terminal 57 Conductive adhesive 61 Chip type solid electrolytic capacitor 63 Exterior resin 64 Anode lead wire 65 Anode terminal 66 cathode terminal 67 Conductive adhesive 68 Insulation member 69 Auxiliary lead wire

Claims (2)

[Claims] 1. A dielectric oxide film is formed on a surface of an anode body in which a rod-shaped anode lead wire is embedded, and a solid electrolyte layer and a cathode layer are sequentially laminated to form an outer periphery of the cathode layer. A chip-type solid electrolytic capacitor comprising a capacitor element and an exterior resin covering the capacitor element, and at least a part of each of the anode terminal and the cathode terminal connected to the anode lead wire and the cathode layer of the capacitor element. In the method for manufacturing a chip-type solid electrolytic capacitor formed so as to be exposed on the mounting surface of, an anode of a lead frame that is an iron-nickel alloy and has a plated surface The terminal is provided with a standing portion, at least the standing portion is a non-plated portion, and a capacitor element is mounted on the lead frame to mount the standing portion and the anode lead wire. After close the sides, the by laser irradiation from the side of the standing portion, a manufacturing method of a chip type solid electrolytic capacitor joined to the anode lead-out wire to melt a portion of the anode terminal. 2. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 1, wherein when the capacitor element is mounted on the lead frame, the standing portion and the side surface of the anode lead wire are brought into contact with each other.