JP2003100554A - Method of manufacturing chip solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly reduce the occurrence of warps caused by a resin coating. SOLUTION: In a method of manufacturing chip solid electrolytic capacitor, a chip solid electrolytic capacitor 1 is provided with capacitor elements 2 formed by forming dielectric oxide coating films on the surfaces of anode bodies having anode lead-out wires 4, and composed of valve-action metal and successively laminating electrolyte layers and cathode layers upon the coating films so that the cathode layers come on the outer peripheral side; and a packaging resin 3 coating the elements 2. Anode terminals 5 and cathode terminals 6 are respectively connected to the anode lead-out wires 4 of the elements 2 and cathode layers and formed to be exposed partially from the packaging resin 3. The method includes a mounting step of mounting the capacitor elements 2 on a lead frame 11 having a plurality of repeating units having portions which become the anode terminals 5 and cathode terminals 6 for mounting the capacitor element 2; a coating step of obtaining a continuous capacitor body by forming the packaging resin 3 so as to cover the elements 2 mounted on the lead frame 11 and, at the same time, to have prescribed gaps 17 composed of unsealed sections among the repeating units; and a cutting step of cutting the continuous capacitor body into pieces so as to have a prescribed shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of 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 With the recent improvement of surface mounting technology, the size of chip type solid electrolytic capacitors used for surface mounting has become 1608 size (1.6 × 0.8 mm □), which is very popular. It is getting smaller.

As a method of manufacturing these miniaturized chip type solid electrolytic capacitors, as disclosed in Japanese Patent Laid-Open No. 2001-6977, after mounting a capacitor element on a lead frame, the capacitor element is mounted. There is a method of covering the entire formed lead frame with an exterior resin and cutting this into a predetermined shape to obtain a chip type solid electrolytic capacitor.

[0004]

In the small chip type solid electrolytic capacitor represented by these 1608 sizes,
It is necessary to use thin lead frames, but when these thin lead frames are used, these lead frames are normally used as terminals during mounting. Since it is required to be located on the bottom surface of the electrolytic capacitor, the outer resin is coated so as to be unevenly distributed only on the upper surface side of the lead frame on which the capacitor element is mounted. The warp of the lead frame coated with the resin becomes very large due to the shrinkage of the lead frame, etc. Therefore, the position of the capacitor element coated for each individual lead frame varies, and the individual capacitor is cut into individual capacitors. There is a problem that not only the process becomes complicated, but also the yield decreases.

Therefore, the present invention has been made by paying attention to the above-mentioned problems, and by significantly reducing the occurrence of warpage due to the resin coating, it is possible to simplify the cutting process and improve the yield. An object of the present invention is to provide a method of manufacturing a solid electrolytic capacitor.

[0006]

In order to solve the above problems, a method for manufacturing a chip type solid electrolytic capacitor of the present invention has an anode lead wire and a dielectric on the surface of an anode body made of valve metal. An oxide film is formed, and further, an electrolyte layer and a cathode layer are sequentially laminated to form a capacitor element having an outer periphery thereof as the cathode layer, and an exterior resin coating the capacitor element. Of the anode lead wire and the cathode terminal connected to the cathode layer and the cathode terminal are formed so that a part of each terminal is exposed from the exterior resin, And a step of mounting the capacitor element on a lead frame having a plurality of repeating units each including a portion serving as a cathode terminal and a plurality of the capacitor elements, and the lead. A coating step of coating the capacitor element mounted on the frame and forming the exterior resin so that a gap is formed between the repeating units by a predetermined unsealed portion to obtain a capacitor continuum; At least a cutting step of cutting into a predetermined shape is included. According to this feature,
By providing a gap due to a predetermined unsealed portion between the repeating units, even if the coating resin shrinks, the shrinkage stress is dispersed, so that the warp of the lead frame can be significantly reduced. Therefore, the cutting process can be simplified and the yield can be improved.

In the method of manufacturing the chip type solid electrolytic capacitor of the present invention, the gap by the unsealed portion is formed so that the portion sealed by the exterior resin formed by the gap becomes an island shape. Is preferred. By doing so, the continuity of the portion sealed by the exterior resin is interrupted, so that the shrinkage stress of these exterior resins can be effectively dispersed, and the warp of the lead frame is further reduced. it can.

In the method of manufacturing the chip type solid electrolytic capacitor of the present invention, it is preferable that the island portions formed in the island shape by the exterior resin have substantially the same size. With this configuration, by making the sizes of the islands substantially the same, the shrinkage stress of the exterior resin on the islands can be homogenized, and the warp of the lead frame can be further reduced.

In the method of manufacturing the chip type solid electrolytic capacitor of the present invention, it is preferable that the island portions have the same shape. With this configuration, the islands have the same shape, which facilitates the cutting in the cutting step.

In the method of manufacturing the chip type solid electrolytic capacitor of the present invention, it is preferable that the shape of the island portion is a square. With this configuration, the vertical and horizontal lengths of the island portions are substantially equal to each other, so that the shrinkage stress of the exterior resin does not vary depending on the direction, and the warp of the lead frame can be further reduced.

[0011]

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.
It is a figure which shows the shape of the lead frame used for this Example, and FIG. 4 is a perspective view which shows the metal mold | die for resin-sealing used for this Example.

Chip type solid electrolytic capacitor 1 of this embodiment
As shown in FIG. 1, the capacitor element 2 and the anode lead wire 4 led out from one side surface of the capacitor element 2 come into contact with each other by being bent, and are welded to the outer periphery of the anode lead wire 4 by welding. An anode terminal 5 provided with a tongue portion 8 to be connected to the anode terminal 5 is disposed below the capacitor element 2 on the side facing the anode terminal 5 with the capacitor element 2 interposed therebetween.
The capacitor element 2 is connected to the lower surface of the outer peripheral portion of the capacitor element 2 electrically and mechanically with a conductive adhesive 10 and the cathode terminal 6 and a portion except the exposed portions of the anode terminal 5 and the cathode terminal 6. Exterior resin 3 to cover
It is mainly composed of and.

As shown in FIG. 3, the anode terminal 5 used in this embodiment has a tongue portion 8 formed in a ribbon shape so as to project laterally from the region where the capacitor element 2 is mounted. Is formed in such a length that the tongue portion 8 can be brought into contact with the anode lead wire 4 by bending the tongue portion 8 from the lead-out portion of the projecting portion, and the lower surface of the capacitor element 2 and the anode terminal to be mounted. When the upper surface of the capacitor element 5 comes into contact with the upper surface of the capacitor element 2, the anode terminal 5 and the negative electrode terminal 6 are short-circuited via the cathode layer formed on the surface of the capacitor element 2, so that insulation is provided between the lower surface of the capacitor element 2. So that the resin 9 intervenes,
An insulating resin 9 is provided on the upper surface.

The capacitor element 2 is an element conventionally used as a solid electrolytic capacitor element, for example, anodized on the surface of a sintered body obtained by molding and sintering valve metal powder such as tantalum. To form a dielectric oxide film as an anode body, and a capacitor element or the like obtained by laminating a solid electrolyte layer such as manganese dioxide and a cathode layer made of carbon or silver paste on the anode body. It can be used preferably. still,
As the solid electrolyte, those using a polymer electrolyte such as polypyrrole can also be used.

In this embodiment, the anode terminal 5, the tongue portion 8 and the cathode terminal 6 are shaped as shown in FIG.
A plurality of repeating units each consisting of a pair of anode terminals 5 and cathode terminals 6 are arranged to form a lead frame 11 on which a plurality of capacitor elements 2 can be mounted. In the present embodiment, four repeating units are used. The units are arranged to form one aggregated unit, and the aggregated unit is sealed with a sealing resin 3 in an island shape without a gap, and these aggregated units are not resin-sealed. Nine gaps 17 are provided to form a sealing unit that seals at the same time, and the sealing units are repeatedly arranged in the longitudinal direction of the lead frame 11.

FIG. 4 shows a mold (lower mold) 30 used to form the exterior resin 3 in this embodiment. The lower mold 30 used in this embodiment is formed with a square recess 31 for sealing the aggregate unit in a square island shape so as to match the arrangement of the aggregate unit of the lead frame 11. In addition, a resin injection port 32 for injecting the softened exterior resin 3 into each of the recesses 31 is provided on one side surface of the lower mold 30, and the resin injection port 3
The exterior resin 3 injected from 2 is filled in each recess 31 through the resin flow path 33. The upper parts of these lower molds 30 are covered with a flat plate-shaped upper mold 40, and the lead frame 11 is aligned between the upper mold 40 and the lower mold 30 to narrow the upper mold 40. It is supposed to be held.

As described above, in this embodiment, the exterior resin 3 is formed in an island shape so that the gap portion 17 surrounds the aggregate unit as described above.
This is preferable because the continuity of the exterior resin 3 can be suitably interrupted and the warp of the lead frame 11 due to the formation of the exterior resin 3 can be significantly reduced. The invention is not limited to this, and a large number of gaps 17 may be provided in the longitudinal direction of the lead frame 11 where warpage is likely to occur, and the gaps 17 in the transverse direction of the lead frame 11 may be reduced.

Further, in this embodiment, the size of the collective unit is the same, and by doing so, the stress associated with the formation of the exterior resin 3 is homogenized in each collective unit. However, the present invention is not limited to this, because it is possible to reduce the occurrence of warp due to the difference in these stresses, the size of a specific set unit is made larger or smaller than other set units. You may choose to do so.

Further, in the present embodiment, the shape of the set unit is the same square, which is preferable not only because it improves the workability of the capacitor cutting operation described later, but also makes it square. Since the vertical and horizontal lengths of the set unit are substantially equal to each other, the shrinkage stress of the exterior resin does not vary depending on the direction, and the warp of the lead frame 11 can be further reduced.
The normally obtained capacitor is a rectangular parallelepiped, which is preferable because the width of the gap 17 can be made larger. However, the present invention is not limited to this, and other shapes, For example, it may be rectangular, circular or elliptical.

The chip type solid electrolytic capacitor 1 of this embodiment will be described below along with its manufacturing process. First, as shown in FIG. 5A, a coating material is applied and dried on the upper surface of the portion of the lead frame 11 to be the anode terminal 5, and the insulating resin 9 is formed. 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 of forming these insulating resins 9.

In the application and drying by the ink jet nozzle, the application and the 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 this 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. 5, the conductive adhesive 10 is applied and formed on the upper surface of the portion to be the cathode terminal 6, and after the application, the capacitor element 2 is mounted as shown in FIG. 5C.

As for the conductive adhesive material 10, 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,
From the viewpoint of adhesion to these cathode layers, etc.
The silver-based conductive adhesive 10 used for mounting C or the like is preferably used, but the present invention is not limited to this, and a solder paste or the like is applied instead of the conductive adhesive 10. Then, after mounting the capacitor element 2, the solder paste is melted to fix the capacitor element 2,
It may be mounted.

After mounting these capacitor elements 2, the conductive adhesive 10 is dried or cured to fix the capacitor elements 2, and after the fixing, as shown in FIG. The tongue portion 8 formed by leading out is bent toward the mounting side of the capacitor element 2 and brought into contact with the anode lead wire 4, and the anode lead wire 4 and the tongue portion 8 are formed.
And are connected by welding to electrically connect the anode lead wire 4 to the anode terminal 5.

Next, as shown in FIG. 5 (e), the lead frame 11 on which the capacitor element 2 is mounted is mounted on the lead frame 11 where the mounting surface of the capacitor element 2 is the lower mold 3.
The resin injection port 32 is arranged so as to be in contact with 0, and the upper die 40 is placed on the lead frame 11 to hold and fix the lead frame 11.
The more fluidized exterior resin is injected and filled, and the filled 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, a 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 is appropriately cured, as shown in FIG. 6 (f), the lead frame 11 with the sealing resin is taken out from the lower mold 30 and the upper mold 40, The protruding portion 3'of the exterior resin and the lead frame 11 are ground from the lower surface of the lead frame 11 using an elastic polishing body 12 so that the lead frame 11 has a predetermined thin wall thickness. In this embodiment, as the elastic polishing body, the outer periphery of the side surface of the elastic polishing body is brought into contact with the lower surface of the lead frame 11 for polishing, but the present invention is not limited to this. A disk-shaped body may be used, and the disk surface may be brought into contact with the lower surface of the lead frame 11 and polished.

As described above, not only the protruding portion 3'of the exterior resin but also the entire lower surface of the lead frame 11 is thinly ground so that the lead frame 11 before resin sealing has high strength. It becomes possible to use a thick lead frame which is hard to warp and has excellent handleability, which can improve workability, and the volume ratio of the lead frame 11 in the obtained capacitor can be reduced by making the entire lower surface of the lead frame 11 thin. The volume ratio of the capacitor element 2 occupying in the capacitor can be made higher since it can be reduced as compared with the case where it is not ground and a larger (higher) capacitor element 2 can be mounted. Although preferred, this embodiment is not so limited.

After these grindings, the lead frame 11
As shown in FIG. 6 (g), the predetermined position of the lead frame 1
By performing R processing so that the corner of 1 becomes a curved part,
The solder accommodating portions 7 and 7'of the anode terminal 5 and the cathode terminal 6 shown in FIG. 2 are formed.

By forming the solder accommodating portions 7 and 7'in this manner, it is possible to sufficiently obtain a contact area with solder when mounting the obtained chip type solid electrolytic capacitor 1 on a substrate. However, it is preferable that the area of the solder fillet exposed on the outer periphery of the chip-type solid electrolytic capacitor 1 can be significantly reduced and the mounting efficiency can be improved. Is not limited to this.

After carrying out the R processing, as shown in FIG.
As shown in (h), after the exposed portion of the lead frame 11 is plated with a metal such as solder plating 14 that can improve the wettability with solder, the chip-type solid electrolytic capacitor 1
On the surface opposite to the exposed surface of the lead frame 11 corresponding to the upper surface of the dicing tape 1, as shown in FIG.
5 is attached, and as shown in FIG.
By forming the cutting groove 16 from the side, the chip type solid electrolytic capacitor 1 having a predetermined shape is obtained.

Here, in this embodiment, as shown in FIG.
In the lead frame 11 after being taken out from the lower mold 30 and the upper mold 40, and the lead frame 11 in which one surface of the lead frame 11 is resin-sealed with the exterior resin 3 ″ as shown in FIG. As a result of comparing the warps of the lead frame 11, the warp of the lead frame 11 formed with the exterior resin 3 ′ of the comparative example is larger than 0.03 mm, and the warp of 0.
While it was not possible to make it less than 03 mm, the warp of the lead frame 11 of this embodiment obtained in FIG. 6 (f) was 0.03 mm or less in all cases. From this result, it is understood that the warp is significantly reduced by forming the gap portion 17 as in the present embodiment.

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 within the scope not departing from the gist of the present invention, Needless to say, it is included in the present invention.

For example, in the above-mentioned embodiment, 4 in a set unit.
Although one capacitor element 2 is incorporated, the present invention is not limited to this, and 6 or 9 capacitor elements 2 may be incorporated in these set units. The number may be appropriately selected according to the shape and size of the set unit.

In the above embodiment, the tongue portion 8 is used to connect the anode lead wire 4 and the anode terminal 5, but the present invention is not limited to this, and the anode terminal 5 is not limited to this.
Is formed into an L-shape in cross-section so that it can be brought into contact with the lower end of the anode lead wire 4, or a pillow-shaped connecting member is arranged between the anode terminal 5 and the anode lead wire 4 for connection. The connection method between the anode lead wire 4 and the anode terminal 5 may be appropriately selected.

[0037]

The present invention has the following effects. (A) According to the invention of claim 1, by providing a gap by the predetermined unsealed portion between the repeating units, the shrinkage stress is dispersed even if the coating resin shrinks.
The warp of the lead frame can be significantly reduced, and thus the cutting process can be simplified and the yield can be improved.

(B) According to the second aspect of the invention, since the continuity of the portion sealed by the exterior resin is interrupted, the shrinkage stress of these exterior resins can be effectively dispersed. The warp of the lead frame can be further reduced.

(C) According to the third aspect of the invention, by making the sizes of the islands substantially the same, the shrinkage stress of the exterior resin on the islands can be homogenized and the warp of the lead frame can be prevented. Can be further reduced.

(D) According to the fourth aspect of the invention, by making the shape of each island part the same, it is possible to facilitate the cutting in the cutting step.

(E) According to the fifth aspect of the present invention, the longitudinal and lateral lengths of the island portions are substantially equal to each other, so that the shrinkage stress of the exterior resin is less likely to differ depending on the direction, and the warp of the lead frame is further reduced. It can be further reduced.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a chip type solid electrolytic capacitor in an example of the present invention.

FIG. 3 is a diagram showing a shape of a lead frame used in this embodiment of the present invention.

FIG. 4 is an external perspective view showing a mold (lower mold) used in this embodiment of the present invention.

FIG. 5 is a diagram showing a manufacturing process of the chip type solid electrolytic capacitor of the present invention.

FIG. 6 is a diagram showing a manufacturing process of the chip solid electrolytic capacitor of the present invention.

FIG. 7 is a diagram showing a lead frame created as a comparative example.

[Explanation of symbols]

1 chip type solid electrolytic capacitor 2 Capacitor element 3 Exterior resin 3'Exterior resin (protruding part) 3 "exterior resin (one side formation) 4 Anode lead wire 5 Anode terminal 6 cathode terminal 7 Solder storage part (anode) 7'Solder housing (cathode) 9 Insulating resin 10 Conductive adhesive 11 lead frame 12 Elastic polishing body 13 recess 14 Solder plating 15 dicing tape 16 cutting groove 17 Gap 30 Lower mold 31 recess 32 Resin injection port 33 resin flow path 40 Upper mold

Claims (5)

[Claims] 1. An anode lead wire having an anode lead wire, a dielectric oxide film is formed on the surface of an anode body made of a valve metal, and an electrolyte layer and a cathode layer are sequentially laminated to form an outer periphery of the cathode layer. A capacitor element and an exterior resin covering the capacitor element, and a part of each of the anode and cathode terminals connected to the anode lead wire and the cathode layer of the capacitor element is the exterior resin. A method for manufacturing a chip-type solid electrolytic capacitor formed so as to be exposed from a lead, wherein a lead having a plurality of repeating units including portions serving as the anode terminal and the cathode terminal and capable of mounting a plurality of the capacitor elements is provided. The mounting process of mounting the capacitor element on the frame, covering the capacitor element mounted on the lead frame, and removing the gap between the repeating units by a predetermined unsealed portion. A chip-type solid comprising at least a coating step of forming the exterior resin so as to have a gap to obtain a continuous capacitor body, and a cutting step of cutting the continuous capacitor body into a predetermined shape. Method of manufacturing electrolytic capacitor. 2. The chip-type solid electrolyte according to claim 1, wherein the gap formed by the unsealed portion is formed so that a portion formed by the gap and sealed by the exterior resin has an island shape. Capacitor manufacturing method. 3. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 1, wherein the island portions formed in the island shape by the exterior resin have substantially the same size. 4. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 2, wherein the island portions have the same shape. 5. The method for manufacturing a chip-type solid electrolytic capacitor according to claim 2, wherein the island portion has a square shape.