JP3175379B2 - Manufacturing method of chip-shaped tantalum solid electrolytic capacitor - Google Patents

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 tantalum solid electrolytic capacitor in chip form. Furthermore, a specific application field of the present invention relates to a molding resin molding technique in a chip-shaped tantalum solid electrolytic capacitor having a capacitor element covered with an exterior resin and having no lead wire.

[0002]

2. Description of the Related Art In recent years, chip-shaped electronic components having no lead wires have been rapidly increasing due to the progress of light and thin electronic devices and the development of surface mounting technology. As chip-type tantalum solid electrolytic capacitors have become smaller and larger in capacity, further miniaturization of chip parts themselves is required.

A conventional chip-shaped tantalum solid electrolytic capacitor has been configured as shown in FIG. That is, in FIG. 4, reference numeral 1 denotes a porous anode body formed by molding and sintering a tantalum metal powder made of a valve action metal, and a part of an anode lead wire 2 made of a tantalum wire led out of the anode body 1 and an anode body. A dielectric oxide film is formed on the entire surface of the substrate 1 by anodic oxidation, and an electrolyte layer such as manganese dioxide is formed on the surface. Reference numeral 3 denotes a Teflon plate attached to the anode lead wire 2, and the Teflon plate 3 is used to form the anode lead wire 2 when the electrolyte layer is formed.
An insulating plate that prevents manganese nitrate from creeping up and adhering manganese dioxide.

[0004] A capacitor element 1a is formed by sequentially laminating a cathode layer 4 composed of a carbon layer and a silver paint layer on the electrolyte layer by an immersion method.
Then, in a portion of the cathode layer 4 of the capacitor element 1a opposite to the anode lead-out line 2, a conical cathode conductor layer 5 having a rounded tip is formed.
The capacitor element 1a and the cathode conductor layer 5 are packaged by molding with a molding resin 6 so that the anode lead-out line 2 is drawn out to one side. After exposing the cathode conductor layer 5 covered with the mold resin 6 by mechanical grinding or the like, the extraction surface of the anode lead-out line 2 of the mold resin 6 including the protruding portion 2a of the anode lead-out line 2 and the lead-out surface Anode metal layer 7 is coated on the peripheral surface adjacent to the surface and mold resin 6 including exposed portion 5a of cathode conductor layer 5 is formed.
The cathode metal layer 8 was formed so as to cover the cathode side end surface and the peripheral surface adjacent to the cathode side end surface.

[0005]

However, in such a conventional chip-shaped tantalum solid electrolytic capacitor,
In the step of holding and holding the anode lead wire 2 drawn out from the capacitor element 1a horizontally and performing molding, if a part of the anode lead wire 2 is fixed to a molding die (not shown), molding is performed. As shown in FIG. 5 and FIG. 6, the anode lead wire 2 held by the holding member 9 bends and deforms from the vicinity where a part of the anode lead wire 2 is fixed by a molding die. That is, when the capacitor element 1a is molded by transfer molding or the like using an epoxy resin or the like to package the capacitor element 1a, the flow direction of the resin melted by the molding pressure is changed from the runner 6a to the cross runner as shown by the resin flow 10. 6b, and then flows to the resin injection gate 6c, and the molten resin flows to the capacitor element 1a loaded in the space of the molding die, so that the entire side surface of one side of the capacitor element 1a is pressed. The resin melted while applying a load flows instantaneously, whereby the capacitor element 1a is pushed by the pressure of the molten resin and the anode lead-out wire 2 cannot withstand, so that the capacitor element 1a bends and deforms along the resin injection direction. It is.

[0006] This bending deformation causes the capacitor element 1
Since the thin cathode layer 4 covering the surface facing the lead-out surface of the anode lead wire 2 and the peripheral surface adjacent to this surface comes into contact with the forming mold, the resin exterior cannot be sufficiently performed, and as a result, the thin Failure in appearance due to exposure of the cathode layer 4 occurred frequently. Also, to expose the outer peripheral surface of the cathode side to the outside,
When a part of the mold resin 6 is removed by grinding or the like, it is necessary to expose the cathode layer 4 so as not to cover the cathode layer 4 while checking the state of exposure of the cathode layer 4, so that the process is very difficult and the productivity is high. It was getting worse. Further, when the thin cathode layer 4 is covered by touching the molding die, there has been a problem that the leakage current and the tan δ value of the capacitor are increased.

SUMMARY OF THE INVENTION The present invention solves such a problem and provides a method of manufacturing a chip-shaped tantalum solid electrolytic capacitor which is excellent in productivity and which can obtain stable electric current of leakage current and tan δ value. It is intended to provide.

[0008]

In order to solve the above-mentioned problems, a method for manufacturing a chip-shaped tantalum solid electrolytic capacitor according to the present invention is characterized in that a part of an anode lead wire embedded inside an anode body is formed.
Conical cathode conductor with one end exposed and a rounded tip
The anode conductor of the capacitor element with the conductor layer formed at the other end
The output wire is joined to the holding member, and then the capacitor element is
The anode lead wire is inserted into the molding die provided with the space to be loaded.
Part of the capacitor is fixed inside the space so that it is fixed.
After loading the element, the shadow of the capacitor element in the space above
Resin through the resin injection gate provided on the pole conductor layer side
Is injected to mold the capacitor element.

[0009]

According to the above manufacturing method, the space inside the molding die is
The injected resin is on the opposite side of the capacitor element anode lead wire.
From the resin injection side.
The capacitor element has a conical cathode with a rounded tip.
Due to the formation of the conductor layer, the pressure load due to the molten resin when injecting the resin into the capacitor element is greatly reduced as compared with the conventional method and becomes extremely stable. As a result, the anode lead wire is not deformed in a curved manner. Disappears. Thereby, even when grinding is performed to expose the outer peripheral surface on the cathode side to the outside, it is possible to eliminate the appearance defect that the cathode layer is exposed. In addition, the strict work management of exposing the cathode layer so as not to be destroyed as in the conventional case is not required, and the productivity can be greatly improved.Also, since the cathode layer is not damaged, leakage current, A stable tan δ value electrical characteristic can be obtained. Moreover the space of the molding die of the resin injection gate
Position on the cathode conductor layer side of the capacitor element
The resin over the entire width of the compact
Because it can set the injection gate, the resin injected into the molding die space portion also done smoothly, as a result, it is possible to significantly reduce pinhole defects generated in the molded body by air entrainment.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a chip-like tantalum solid electrolytic capacitor obtained by a manufacturing method according to an embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a porous tantalum metal powder formed of a valve metal and molded and sintered. On the anode body, a dielectric oxide film is formed by anodic oxidation on a part of the anode lead wire 12 composed of a tantalum wire led from the anode body 11 and the entire surface of the anode body 11, and an electrolyte layer such as manganese dioxide is formed on the surface. Is formed. Reference numeral 13 denotes a Teflon plate attached to the anode lead wire 12, and this Teflon plate 13 is an insulating plate for preventing manganese nitrate from creeping up to the anode lead wire 12 and forming manganese dioxide during the formation of the electrolyte layer.

A capacitor element 11a is formed by sequentially laminating a cathode layer 14 composed of a carbon layer and a silver paint layer on the electrolyte layer by a dipping method. In a portion of the cathode layer 14 of the capacitor element 11a opposite to the anode lead-out line 12, a conical cathode conductor layer 15 having a rounded tip is formed. The cathode conductor layer 15 is packaged by molding with a molding resin 16 so that the anode lead wire 12 is drawn out to one side.
Then, after the cathode conductor layer 15 covered with the mold resin 16 is mechanically exposed by grinding or the like, the lead-out surface of the anode lead-out line 12 of the mold resin 16 including the protrusion 12a of the anode lead-out line 12 is formed. Anode metal layer 17 is coated on the peripheral surface adjacent to the lead-out surface, and a cathode metal layer is formed on the cathode side end surface of mold resin 16 including exposed portion 15a of cathode conductor layer 15 and the peripheral surface adjacent to the cathode side end surface. 18 is coated.

FIGS. 2 and 3 show a resin molded product obtained by resin molding by a transfer molding method in a molding process for manufacturing the chip-shaped tantalum solid electrolytic capacitor shown in FIG. 1. FIG. FIG. 3 is a perspective view of a resin molded body after resin molding, and FIG. 3 is a schematic view showing a flow of resin during resin molding. 2 and 3, capacitor element 11a is placed in the space of the molding die so that a part of anode lead wire 12 held horizontally by holding member 19 is fixed to the molding die (not shown). After loading and resin molding by the transfer molding method, the film gate 16a
From the resin injection gate 16b located on the surface of the molding die opposite to the anode lead-out line 12, and is injected into the space of the molding die. That is, the resin is formed of the cathode conductor layer 15 formed on the capacitor element 11a.
As shown by the resin flow 20 from the rounded tip, the pressure load due to the molten resin at the time of injecting the resin into the capacitor element 11a is centered on the rounded tip of the cathode conductor layer 15. Therefore, the pressure load can be reduced as compared with the conventional method.

Further, the direction of resin injection is
Since the direction is the same as the direction in which the anode lead-out wire 12 drawn from 1a is held by the holding member 19, that is, the stable direction, the anode lead wire 12 is also stable against the pressure load by the molten resin.
As a result, since the bending of the anode lead wire 12 unlike the conventional method is eliminated, even when the mold resin 16 is ground to expose the outer peripheral surface on the cathode side to the outside, the cathode layer 1 is not crushed.
The appearance defect that 4 is exposed can be eliminated.
In addition, since it is not necessary to perform strict work management of exposing the cathode layer 14 so as not to break it as in the related art, the productivity can be greatly improved, and the cathode layer 14 is not damaged. Leakage current, ta
Electric characteristics having a stable nδ value can be obtained.

Further, the use of the molding technique in the manufacturing method of the present invention has the following advantages. For example, in the case where the number of samples n of the chip-shaped solid electrolytic capacitors of the present invention and the conventional method is set to four, respectively, comparing FIG. 2 and FIG. Looking at the molding die and the amount of resin used, first, when the molding die is manufactured, the molding die used in the manufacturing method of the present invention is the same as the molding die of the conventional method. Approximately 30% of the mold size can be reduced. Furthermore, even if the capacitor element to be loaded into the space of the molding die for producing the resin body of the chip-shaped solid electrolytic capacitor has the same dimensions,
Regarding the path for flowing resin into the space of the molding die,
In the conventional method, the resin flows from the runner 6a and the cross runner 6b to the resin injection gate 6c. However, the molding die in the manufacturing method of the present invention uses one film gate 16a which also serves as the resin injection gate 16b. Is about 1/4 of the thickness of the runner 6a. As can be seen from the thicknesses and distances of the runner 6a and the film gate 16a, the molding die used in the manufacturing method of the present invention uses a smaller amount of the molding resin.

In the molded article obtained by the molding die used in the manufacturing method of the present invention, the capacitor element 11a is connected to the resin injection gate 16b connected to the molded article.
When the mold resin 16 is cut off, the anode lead-out wire 12 is still held by the holding member 19, so that the cutting can be easily performed as compared with the conventional method. That is, in the case of the molded body manufactured by the conventional method, the molding resin 6 for each capacitor must be cut and twisted around the resin injection gate 6c, but the molding die used in the manufacturing method of the present invention is required. In the case of the obtained molded body, a large number of mold resins 16 are
When the resin injection gate 16a is bent upward or downward at an angle of about 30 ° around the resin injection gate 16b, it is easily divided.

Further, the resin injection gate 16b for injecting the resin into the space of the molding die can be set over the entire width of the molded body in which the capacitor element 11a is covered with the molding resin 16, so that the resin injection gate 16b extends to the space of the molding die. Resin injection can be performed smoothly, and as a result, pinhole defects generated in the molded body due to entrainment of air can be significantly reduced.

In the above embodiment, when resin molding is performed, resin molding is performed by transfer molding. However, resin molding is performed by injection molding using a thermoplastic resin such as a liquid crystal polymer or a PPS resin. It may be.

[0018]

As described above, according to the manufacturing method of the present invention, the inside of the space of the molding die into which the capacitor element is loaded is formed .
Distribution of the resin injection gate to the cathode conductor layer side of the capacitor element
And location, the resin is injected from the top Symbol resin injection gate in this state
Since the capacitor element so as to mold package Te,
The resin injected into the space of the molding die is a capacitor element
From the opposite side of the anode lead wire,
Also, the tip of the capacitor element on the resin injection side should be rounded.
Because the conical cathode conductor layer is formed , the pressure load at the time of injecting the resin into the capacitor element is greatly reduced compared to the conventional method, and becomes extremely stable.
As a result, the anode lead wire does not deform in a curved manner.
Thereby, even when grinding is performed to expose the outer peripheral surface on the cathode side to the outside, it is possible to eliminate the appearance defect that the cathode layer is exposed. In addition, the strict work management of exposing the cathode layer so as not to be destroyed as in the related art is unnecessary, and the productivity can be greatly improved.Also, since the cathode layer is not damaged, leakage current, A stable tan δ value electrical characteristic can be obtained.

Further, by positioning the resin injection gate on the surface of the molding die in which the capacitor element is to be mounted, the surface facing the anode lead-out line, the resin injection gate for injecting the resin into the space of the molding die is provided with a capacitor. Since the element can be set over the entire width of the molded body that is covered with the molding resin, the resin can be smoothly injected into the space of the molding die,
As a result, it is possible to greatly reduce pinhole defects generated in the molded body due to entrainment of air.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor obtained by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a resin molded product obtained by resin molding by a transfer molding method in a molding process for manufacturing the tantalum solid electrolytic capacitor.

FIG. 3 is a schematic diagram showing the flow of resin during resin molding.

FIG. 4 is a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor obtained by a conventional manufacturing method.

FIG. 5 is a perspective view showing a resin molded body obtained by resin molding by a transfer molding method in a molding step for manufacturing the tantalum solid electrolytic capacitor.

FIG. 6 is a schematic diagram showing the flow of resin during resin molding.

[Explanation of symbols]

 11a Capacitor element 12 Anode lead wire 16 Mold resin 16b Resin injection gate 19 Holding member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Kim 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-30412 (JP, A) 95724 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01G 9/08 H01G 9/00 H01G 9/004

Claims (1)

(57) [Claims] 1. An anode lead wire embedded in an anode body.
Cone shaped with part exposed at one end and rounded at the tip
The above of the capacitor element in which the cathode conductor layer is formed at the other end
Connect the anode lead to the holding member, and then
The anode is guided to the molding die provided with the space where the element is loaded.
A part of the outgoing line is fixed and
After loading the capacitor element, the capacitor element in the space
Through the resin injection gate provided on the cathode conductor layer side of the
Mold the capacitor element by injecting resin
A method for manufacturing a chip-shaped tantalum solid electrolytic capacitor to be packaged.