JPH06236834A - Manufacture of solid tantalum chip capacitor - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a solid tantalum chip capacitor having excellent mechanical strength and reliability in a deflection test and the like and also a stabilized mountability when a mounting machine is used. CONSTITUTION:The resin injection gate 32, to be used for injection of resin into the space part formed by the upper mold 30b and the lower mold 30a, is positioned on both sides opposing to the anode lead-out wire 22 of the mold. By having a mold resin outer covering released from the lower mold 31a by pushing up by a releasing pin 33 the part close to the tip on the side of the resin injection gate 32 on the mold resin outer covering formed by injecting resin from the resin injection gate 32, the generation of the defective part such as a recessed part and the like on the outer surface of the mold resin outer covering can be prevented even when there is a defect on the releasing pin 33.

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 chip-shaped tantalum solid electrolytic capacitor. More specifically, the specific field of use of the present invention relates to a molding resin molding technique for a chip-shaped tantalum solid electrolytic capacitor having a capacitor element covered with an outer resin and having no lead wire.

[0002]

2. Description of the Related Art In recent years, chip-shaped electronic parts having no lead wire have been rapidly increasing due to the miniaturization of electronic equipment and the progress of surface mounting technology. In the chip-type tantalum solid electrolytic capacitor, further miniaturization of the chip component itself is required as the miniaturization and the large capacity progress.

A conventional chip-shaped tantalum solid electrolytic capacitor is constructed as shown in FIG. That is, in FIG. 3, reference numeral 1 denotes a porous anode body obtained by molding and sintering tantalum metal powder made of a valve metal, and a part of an anode lead wire 2 made of tantalum wire derived from the anode body 1 and the anode body. A dielectric oxide film is formed on the entire surface of No. 1 by anodic oxidation, and an electrolyte layer of manganese dioxide or the like is formed on this surface. Reference numeral 3 is a Teflon plate attached to the anode lead wire 2, and this Teflon plate 3 is used for forming the electrolyte layer.
It is an insulating plate that prevents manganese nitrate from creeping up and adhering manganese dioxide. A capacitor layer 1a is formed by sequentially stacking a cathode layer 4 composed of a carbon layer and a silver coating layer on the electrolyte layer by a dipping method.
Are configured.

The portion of the cathode layer 4 of the capacitor element 1a located on the opposite side of the anode lead wire 2 is
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 molded with a molding resin 6 so that the anode lead wire 2 is drawn out to one side. Then, after exposing the cathode conductor layer 5 covered with the mold resin 6 by mechanical grinding or the like, the lead surface of the anode lead wire 2 of the mold resin 6 including the protruding portion 2a of the anode lead wire 2 and this lead wire. The peripheral surface adjacent to the surface is coated with the anode metal layer 7, 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 coated.

[0005]

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

That is, FIG. 4 shows a molded body which is resin-molded by a resin molding die.
The anode lead wire 2 held by the holding member 10 is horizontally fixed by a lower mold and an upper mold of the molding die (neither is shown), and the lower mold and the upper mold of the molding die are closed. The capacitor element 1a is loaded into a space formed when the resin is formed, and resin molding is performed so that a part of the anode lead-out wire 2 is fixed. The resin injected from the film runner 11 is injected from the resin injection gate 11a. A molded body that enters the space of the molding die and is covered with the molding resin 6 shown in FIG. 4 is formed.

Next, the lower die and the upper die 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 wire 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 causes the space 11 of the molding die.
Then, a molded body which is covered with the molding resin 6 so as to enclose the capacitor element 1a loaded in the above is manufactured. When the exterior of the mold resin 6, that is, the transfer molding is completed, the upper mold 12b is opened, and then the mold release pin 13 installed on the lower mold 12a is used to separate the molded body from the lower mold 12a. 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 at the time of resin molding,
Further, when the molded body is released from the mold, it moves up to a fixed position above, but due to dust or molten resin burr that prevents the mold release pin 13 from moving up and down, it does not move down to a fixed position during resin molding. When the resin is molded as it is when it stops while protruding upward, a concave portion 9 or a convex portion (not shown) is formed in the substantially central portion below the molding resin 6 as shown in FIG. It was a thing.

When the chip-shaped tantalum solid electrolytic capacitor is mounted on the printed circuit board with cream solder or the like and then the printed circuit board for mounting evaluation is subjected to a flexure test, resin cracks are generated in the recessed section 9 at the thin portion of the mold resin 6. Was occurring. Further, if a convex portion is formed at this portion, mounting of the chip-shaped tantalum solid electrolytic capacitor by a mounting machine becomes unstable, and there is a problem that it cannot be mounted on a printed circuit board.

The present invention solves such problems, and it is possible to obtain a chip-shaped tantalum which is excellent in reliability of mechanical strength in a flexure test and the like and can be stably mounted 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 achieve the above object, a method of manufacturing a chip-shaped tantalum solid electrolytic capacitor according to the present invention comprises a capacitor element having an anode lead wire and a holding element for holding the anode lead wire of the capacitor element. A member, a molding die including an upper die and a lower die for fixing the anode lead wire and forming a space for loading the capacitor element, and an upper die and a lower die in the molding die. And a resin injection gate for fixing the anode lead wire and injecting a resin into the space to coat the capacitor element with a mold resin. The resin injection gate is a molding metal into which the capacitor element is loaded. It is positioned on the side facing the anode lead wire of the mold, and a resin is injected from this resin injection gate to produce a molded resin outer package that houses the capacitor element. Is obtained so as to release the molded resin sheathing body from the lower tool tip vicinity of the resin injection gate side of Rudo resin sheathing body pushes a release pin.

[0012]

According to the above manufacturing method, the anode lead wire of the capacitor element is fixed by the upper mold and the lower mold in the molding die including the upper mold and the lower mold in which the space for loading the capacitor element is formed. Then, a resin injection gate for injecting a resin into the space and covering the capacitor element with a mold resin is located on the surface side facing the anode lead wire of the molding die in which the capacitor element is loaded. A resin is injected from a resin injection gate to produce a molded resin exterior body that houses the capacitor element, and a portion near the tip on the resin injection gate side of the molded resin exterior body is pushed up by a mold release pin to remove it from the lower mold. Since the mold resin outer package is designed to be released from the mold, a defect such as a concave portion or a convex portion does not occur in the lower center of the mold resin outer package as in the conventional case. Even if a defect of the mold release pin causes a defective portion such as a concave portion or a convex portion in the vicinity of the tip on the resin injection gate side of the molded resin exterior body, the vicinity of the tip end of the mold resin exterior body is generated. Is shaved off to expose a part of the cathode conductor layer provided on the surface side of the capacitor element facing the anode lead-out line, so that 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 package without a defective portion such as a concave portion or a convex portion, and a substantially uniform thickness of the molded resin. It is possible to obtain a product having excellent mechanical strength reliability and 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 a manufacturing method according to an embodiment of the present invention. In FIG. 1, reference numeral 21 is a porous tantalum metal powder formed by molding and sintering tantalum metal powder made of valve metal. In the anode body, a dielectric oxide film by anodic oxidation is formed on a part of the anode lead wire 22 formed of the tantalum wire led from the anode body 21 and the entire surface of the anode body 21, and an electrolyte layer such as manganese dioxide is formed on this surface. Is formed. 23 is an anode lead wire 2
The Teflon plate 22 is attached to No. 2, and this Teflon plate 22 is an insulating plate that prevents manganese nitrate from crawling up and adhering to manganese dioxide to the anode lead wire 22 when the electrolyte layer is formed.

Further, a capacitor element 21a is formed by sequentially forming a cathode layer 24 composed of a carbon layer and a silver coating layer on the electrolyte layer by a dipping method. Then, a conical cathode conductor layer 25 having a rounded tip is formed on a portion of the capacitor element 21a located on the side opposite to the anode lead wire 22 in the cathode layer 24, and thereafter, the capacitor element 21a and the cathode conductor layer 25 are formed. The cathode conductor layer 25 is packaged by molding with a molding resin 26 so that the anode lead wire 22 is drawn out to one side.
Then, the cathode conductor layer 25 that is covered with the mold resin 26 is exposed by shaving the mold resin 26 thickly by mechanical grinding or the like, and then exposing the anode lead wire 2.
The lead-out surface of the anode lead wire 22 of the mold resin 26 including the two protrusions 22a and the peripheral surface adjacent to the lead-out surface are covered with the anode metal layer 27, and the exposed portion 25a of the cathode conductor layer 25 is included. 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 process 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.
When 2 is fixed horizontally by the lower mold 30a and the upper mold 30b of the molding mold and molded, the lower mold 30a of the molding mold is used.
By injecting resin from the resin injection gate 32 into the space 31 formed when the upper mold 30b is closed, the capacitor element 21a loaded in the space 31 is wrapped with the molding resin 26. Mold the resin exterior body.

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

In this case, the resin injection gate 32 is located on the surface side of the molding die on which the capacitor element 21a is mounted, which faces the anode lead wire 22, and the resin injection gate 32 is a film through which the resin flows. It communicates with the runner 34. Further, the release pin 33 is installed in the lower mold 30a so as to push up a portion in the vicinity of the tip on the resin injection gate 32 side in the molded resin outer package, that is, a portion corresponding to the cathode conductor layer 25 in the capacitor element 21a. There is.

As described above, the resin injection gate 32 in the molded resin exterior body containing the capacitor element 21a produced by injecting the resin from the resin injection gate 32.
Since the mold resin outer package is released from the lower mold 30a by pushing up the part near the tip on the side with the mold release pin 33, as in the conventional case, a recess or a recess is formed in the approximate center below the mold resin package. The defective portion of the convex portion does not occur.

In addition, if the release pin 33 stops due to some trouble in a state where it does not drop to a fixed lower position and protrudes upward during resin molding, when the resin is molded as it is, the mold resin A defective portion such as a concave portion or a convex portion will be generated in the vicinity of the tip on the resin injection gate 32 side in the outer package, and this vicinity of the tip is a portion corresponding to the cathode conductor layer 25 in the capacitor element 21a, and Since the portion near the tip is scraped off by mechanical grinding or the like 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, the outer surface of the molded resin outer package can be flat with no defective portions such as concave portions or convex portions. Further, as a result, a mold resin having a substantially uniform wall thickness can be obtained, so that it is possible to obtain a resin having excellent mechanical strength reliability in a bending test and the like, and stable mountability by a mounting machine.

In the above embodiments, when resin molding is performed, the resin molding is performed by the transfer molding method. However, the resin molding is performed by an injection molding method using a thermoplastic resin such as liquid crystal polymer and PPS resin. It's okay.

[0021]

As described above, according to the manufacturing method of the present invention, the upper mold and the lower mold in the molding mold including the upper mold and the lower mold in which the space for loading the capacitor element is formed. A resin injection gate for fixing the anode lead-out wire of the capacitor element under pressure, and injecting resin into the space to coat the capacitor element with a mold resin, and an anode lead-out wire of a molding die in which the capacitor element is loaded. Positioned on the opposite surface side, a resin is injected from this resin injection gate to produce a molded resin exterior body that houses the capacitor element, and the vicinity of the tip of the molded resin exterior body on the resin injection gate side is released. Since the mold resin outer package is released from the lower mold by pushing it up with a pin, a concave or convex portion is formed in the lower center of the mold resin outer package as in the conventional case. No defective portion is generated, and even if a defect of the mold release pin causes a defective portion such as a concave portion or a convex portion in the vicinity of the tip on the resin injection gate side of the mold resin outer package, this mold resin Since the vicinity of the tip of the outer package is scraped off to expose a part of the cathode conductor layer provided on the surface side facing the anode lead wire of the capacitor element to the outside, the defective portion of the concave portion or the convex portion is As a result, it is possible to obtain a flat outer surface of the molding resin outer package without any defective portion such as a concave portion or a convex portion, and to obtain a molding resin having a substantially uniform thickness. Therefore, it is possible to obtain a product having excellent mechanical strength reliability in a flexure test and the like, and stable mountability by a mounting machine. .

[Brief description of 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 same 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 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 mold 30b Upper mold 31 Space part 32 Resin injection gate 33 Release pin

Claims (1)

[Claims] 1. A capacitor element having an anode lead wire,
A holding member for holding the anode lead-out wire of the capacitor element, a mold for fixing the anode lead-out wire, and an upper mold and a lower mold for forming a space for loading the capacitor element, and the molding die. A resin injection gate for fixing the anode lead wire with an upper mold and a lower mold in a mold and injecting a resin into the space to coat the capacitor element with a mold resin; The gate is located on the surface side of the molding die on which the capacitor element is mounted, which faces the anode lead wire, and a resin is injected from the resin injection gate to produce a molded resin outer package for incorporating the capacitor element. A chip-shaped tantalum solid for releasing the mold resin outer package from the lower mold by pushing up the vicinity of the tip on the resin injection gate side of the mold resin outer package with a release pin. Method for producing a solution capacitor.