JP3175380B2 - 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 a configuration as shown in FIG. That is, in FIG. 3, reference numeral 1 denotes a porous anode body formed by molding and sintering a tantalum metal powder made of a valve 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. Further, a cathode layer 4 composed of a carbon layer and a silver paint layer is sequentially formed on the electrolyte layer by an immersion method, thereby forming a capacitor element 1a.
Is composed.

A portion of the cathode layer 4 of the capacitor element 1a opposite to the anode lead-out line 2 includes:
A conical cathode conductor layer 5 having a rounded tip is formed, and then the capacitor element 1a and the cathode conductor layer 5 are formed.
Is formed by resin molding with a mold resin 6 so that the anode lead wire 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 The anode metal layer 7 is coated on the peripheral surface adjacent to the surface, and the cathode metal layer 8 is formed on the cathode side end surface of the mold resin 6 including the exposed portion 5a of the cathode conductor layer 5 and the peripheral surface adjacent to the cathode side end surface. Was formed.

[0005]

However, in such a conventional chip-shaped tantalum solid electrolytic capacitor, a molded resin outer casing in which the capacitor element 1a and the cathode conductor layer 5 are externally covered with a molding resin 6 is formed from a molding die. In the case of releasing the mold, there is a problem that a release pin provided on the lower mold causes a concave portion 9 or a convex portion (not shown) to be generated at a substantially central portion on the lower mold side of the mold resin 6. Was.

That is, FIG. 4 shows a molded article formed by resin molding using a resin molding die.
The anode lead wire 2 held by the holding member 10 is horizontally fixed by a lower die and an upper die (neither is shown) of the forming die, and the lower die and the upper die of the forming die are closed. In addition, the capacitor element 1a is loaded into a space formed at the same time, and resin molding is performed so that a part of the anode lead wire 2 is fixed. The injected resin flowing from the film runner 11 flows from the resin injection gate 11a. A molded product that enters the space of the molding die and is covered with the molding resin 6 shown in FIG. 4 is obtained.

Next, the lower mold and the upper mold for holding the anode lead wire 2 will be described in more detail with reference to FIG.

FIG. 5 shows a state in which the lower die 12a and the upper die 12b are closed and the molding die fixes the anode lead-out line 2. In this state, the resin of the molding die is formed by the transfer molding method. When the resin is injected from the injection gate 11a, the resin melted by the resin molding pressure becomes the space 11 of the molding die.
Then, a molded article covered with the mold resin 6 is produced so as to enclose the capacitor element 1a loaded in. When the exterior by the molding resin 6, that is, the transfer molding, is completed, the upper mold 12 b is opened, and then, in order to release the molded body from the lower mold 12 a, the release pins 13 installed on the lower mold 12 a are used. The molded body is pushed upward from below to release the molded body from the lower mold 12a. in this case,
The release pin 13 is lowered to a fixed position below during resin molding,
When the molded product is released from the mold, it is raised to an upper fixed position. However, due to dust or molten resin burr that prevents the release pin 13 from moving up and down, the molded product does not drop to a lower fixed position during resin molding. When the resin is molded as it is when it stops in the state of protruding upward, as shown in FIG. 3, a concave portion 9 or a convex portion (not shown) is generated at a substantially central portion below the mold resin 6. Was something.

When a chip-shaped tantalum solid electrolytic capacitor is mounted on a printed board with cream solder or the like, and the printed board for mounting evaluation is subjected to a bending test, a resin crack is formed in the thin portion of the mold resin 6 due to the recess 9. Had occurred. Further, if a convex portion is formed in this portion, the mounting of the chip-shaped tantalum solid electrolytic capacitor at the time of mounting by a mounting machine becomes unstable, and there has been a problem that it cannot be mounted on a printed circuit board.

The present invention solves such a problem, and provides a chip-shaped tantalum having excellent mechanical strength reliability in a deflection test and the like, and having a stable mountability by a mounting machine. It is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor.

[0011]

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 shape with one end exposed and the other end rounded
Capacitor element with cathode conductor layer formed
The mold is formed with the upper and lower dies closed.
The anode lead-out wire
Press and fix with the mold and the lower mold, and in this state,
Of the capacitor provided on the cathode conductor layer side of the capacitor element
By pressing the melted exterior resin through the entrance gate
The capacitor element in a mold,
The mold is opened and provided to communicate with the cathode conductor layer side of the lower mold.
Push up the release pin to remove the molded
After release, the package containing the release pin traces of this molded product
Remove resin and part of cathode conductor layer by grinding etc.
The cathode extraction part is exposed by exposing the cathode conductor layer
Is formed .

[0012]

According to the above-described manufacturing method, unlike the conventional case, a defective portion such as a concave portion or a convex portion does not occur at a substantially central portion below the mold resin outer package. Cathode conductor in molded resin sheath
Even if a defect portion such as a concave portion or a convex portion occurs on the layer side , the cathode conductor layer in this molded resin outer package is
Because the scraped to expose a part of the outside,
Defect portion above Symbol concave or convex portion is to be removed by hand, as a result, the outer surface of the molded resin sheathing body can get what flat no defect portion of the concave or convex portion, and the mold resin Since a substantially uniform thickness can be obtained, it is possible to obtain excellent mechanical strength reliability in a deflection test and the like, and also obtain a stable mountability by a mounting machine.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a chip-shaped tantalum solid electrolytic capacitor obtained by the manufacturing method according to one embodiment of the present invention. In FIG. 1, reference numeral 21 denotes a porous tantalum metal powder formed by molding and sintering a tantalum metal powder composed of a valve action metal. On the anode body, a dielectric oxide film is formed by anodic oxidation on a part of an anode lead wire 22 composed of a tantalum wire led out of the anode body 21 and the entire surface of the anode body 21, and an electrolyte layer such as manganese dioxide is formed on the surface. Is formed. 23 is an anode lead wire 2
2, the Teflon plate 22 is an insulating plate for preventing manganese nitrate from creeping up to the anode lead wire 22 during the formation of the electrolyte layer and preventing manganese dioxide from adhering.

A capacitor element 21a is formed by sequentially laminating a cathode layer 24 composed of a carbon layer and a silver paint layer on the electrolyte layer by an immersion method. A conical cathode conductor layer 25 having a rounded tip is formed in a portion of the capacitor element 21a opposite to the anode lead-out line 22 in the cathode layer 24. Thereafter, the capacitor element 21a and the The cathode conductor layer 25 is packaged by molding with a molding resin 26 so that the anode lead-out wire 22 is drawn out to one side.
After exposing the cathode conductor layer 25 covered with the mold resin 26 by shaving the mold resin 26 thick by mechanical grinding or the like, the anode lead wire 2
An anode metal layer 27 is formed on the lead surface of the anode lead-out line 22 of the mold resin 26 including the two protrusions 22a, and a peripheral surface adjacent to the lead surface is covered with an exposed portion 25a of the cathode conductor layer 25. The cathode metal layer 2 is formed on the cathode side end surface of the mold resin 26 and the peripheral surface adjacent to the cathode side end surface.
8 is coated.

FIG. 2 shows a molding die of a transfer molding method used in a resin molding step for manufacturing the chip-shaped tantalum solid electrolytic capacitor shown in FIG.
In FIG. 2, the anode lead wire 2 held by the holding member 29 is shown.
When the mold 2 is horizontally fixed with the lower mold 30a and the upper mold 30b of the molding mold and the molding is performed, the lower mold 30a of the molding mold is used.
The resin is injected from the resin injection gate 32 into the space 31 formed when the upper mold 30b is closed, so that the capacitor element 21a loaded in the space 31 is enveloped by the mold resin 26. A molded resin outer body is formed.

After the molding, the upper mold 30b rises upward, and is in a state before the molding, and is in a standby state. In this standby state, the release pin 33 installed on the lower mold 30a is moved upward from below, that is, in the direction of arrow Y, thereby pushing up the molded resin molded body from below to move the molded resin exterior body to the molding die. Lower mold 30
Release from a.

In this case, the resin injection gate 32 is located on the side of the molding die in which the capacitor element 21a is to be mounted, facing the anode lead-out line 22, and the resin injection gate 32 is a film through which the resin flows. It communicates with the runner 34. The release pin 33 is installed on the lower mold 30a so as to push up the vicinity of the tip on the resin injection gate 32 side of the molded resin exterior body, that is, the portion corresponding to the cathode conductor layer 25 in the capacitor element 21a. I have.

As described above, the resin injection gate 32 in the molded resin exterior body in which the capacitor element 21a manufactured by injecting the resin from the resin injection gate 32 is provided.
The vicinity of the tip of the side is pushed up by the release pin 33 to release the mold resin exterior body from the lower mold 30a. The occurrence of a defective portion of the convex portion is eliminated.

Also, if the release pin 33 stops due to some trouble in a state of protruding upward without lowering down to a fixed position at the time of resin molding, if the resin is molded as it is, the molding resin Defects such as concave portions or convex portions are generated near the tip of the exterior body on the side of the resin injection gate 32, and the vicinity of the tip is a portion corresponding to the cathode conductor layer 25 in the capacitor element 21a, and Since the vicinity of the tip is shaved off by mechanical grinding or the like in order to expose a part of the cathode conductor layer 25 to the outside, the defective portion of the concave portion or the convex portion is removed by this. As a result, it is possible to obtain a flat outer surface of the molded resin outer casing without any defective portions such as concave portions or convex portions. In addition, since the thickness of the mold resin can be substantially uniform, the reliability of the mechanical strength in a deflection test or the like is excellent, and the moldability of the mounting machine can be stabilized.

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.

[0021]

As described above, according to the manufacturing method of the present invention, the release pin is arranged on the cathode conductor layer side of the capacitor element.
However, since the traces of the release pin are removed, a defective portion such as a concave portion or a convex portion does not occur at a substantially central portion below the mold resin outer body as in the conventional case, and Even if a defect of a concave portion or a convex portion occurs on the cathode conductor layer side of the molded resin outer casing due to a failure of the pin, the shade of the molded resin outer casing is not affected.
For Gokushirube conductor layer to be scraped away to expose a part of the outside, the defect portion above Symbol concave or convex portion is to be removed by this, the outer surface of the result, the molded resin sheathing body recess Alternatively, it is possible to obtain a flat product having no defective portion of the convex portion, and to obtain a product having a substantially uniform thickness of the mold resin. With respect to the mounting performance, a stable one can be obtained.

[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 partial cross-sectional view showing a resin molding die for manufacturing the tantalum solid electrolytic capacitor.

FIG. 3 is a cross-sectional view of a chip-shaped tantalum solid electrolytic capacitor obtained by a conventional manufacturing method.

FIG. 4 is a perspective view showing a resin molded body of the tantalum solid electrolytic capacitor.

FIG. 5 is a partial cross-sectional view showing a resin molding die for manufacturing the tantalum solid electrolytic capacitor.

[Explanation of symbols]

 21a Capacitor element 22 Anode lead wire 25 Cathode conductor layer 26 Mold resin 29 Holding member 30a Lower die 30b Upper die 31 Space 32 Resin injection gate 33 Release pin

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-30412 (JP, A) JP-A-59-33235 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 9/08 H01G 9/00 H01G 9/004 H01G 13/00 321

Claims (1)

(57) [Claims] 1. An anode lead wire embedded in an anode body.
A circle with a part exposed at one end and a rounded tip at the other end
Capacitor element with cone-shaped cathode conductor layer
With the upper and lower dies closed for the mold for molding
Load into the space to be formed
With the upper mold and the lower mold.
Provided on the cathode conductor layer side of the capacitor element in the space
Press the molten exterior resin through the resin injection gate.
And mold the capacitor element with
Open the molding die and install it in communication with the cathode conductor layer side of the lower die.
Pressing up the released release pin and forming the mold exterior
After removing the molded product, the molded product including the release pin traces
Of the exterior resin and part of the cathode conductor layer by grinding, etc.
Cathode removal by removing and exposing the cathode conductor layer
A method for manufacturing a chip-shaped tantalum solid electrolytic capacitor in which a protruding portion is formed .