JPS5963717A - Manufacturing method of chip-shaped solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a chip-shaped solid state capacitor.

In conventional chip-shaped solid electrolytic capacitors, for example, an anode body formed by molding and sintering tantalum powder is formed with an anodized film, a semiconductor layer, a carbon layer, a barrel, and a 1E silver paint layer in that order. After that, the appropriate anode and cathode terminals were attached, and a protective cover was applied to complete the work. Furthermore, up to the formation of the conductive silver paint layer, a large number of anode bodies are attached to a long strip-shaped metal plate and processed all at once.

At the stage of attaching the anode and cathode terminals, the anode is usually welded and the cathode is attached by soldering to the terminal chain, which is separated from the gold maple plate and prepared separately as individual elements. 7 and apply the protective coating L7 individually.
1 by disconnecting it from the terminal again.
Creating individual capacitors.

In such prior art, when the cathode terminal is first soldered, the conductive silver paint melts into the solder, partially disappears, and a carbon layer is formed.
The solder layer comes into contact with the solder layer without intervening the silver paint layer, resulting in an increase in the impedance and equal series resistance of the capacitor. To prevent this, it is necessary to use expensive silver-containing solder and to strictly control temperature and time during soldering. Particularly in chip capacitors, since the elements are extremely small and therefore have a small heat capacity, both temperature and time must be controlled within a very narrow range.

Another conventional method for preventing this is to provide a metal plating layer on top of the silver paint layer or carbon layer. However, a carbon layer that can penetrate well into the porous semiconductor layer and connect to the semiconductor layer with low resistance is difficult to achieve when it is immersed in a plating solution.

It is unavoidable that the plating solution permeates through that layer and further penetrates into the semiconductor layer.

Therefore, a long period of cleaning was required, and even then, capacitors with large leakage current or unstable due to residual plating solution were observed.

An object of the present invention is to place a large number of anode bodies on a long strip-shaped metal plate, and to carry out the entire process from the formation of an anodized film to the formation of a protective coating of a capacitor, an anode, and a cathode terminal on the metal plate. It is an object of the present invention to provide a method for manufacturing a chip-shaped solid electrolytic capacitor that is processed all at once without separating it from the capacitor.

The next object of the present invention is to form a metal plating layer after providing a resin layer to prevent semiconductor build-up and a carbon layer in contact with the resin layer to prevent the plating solution from seeping over the entire surface of the anode body. To provide an inexpensive manufacturing method for a chip-shaped solid electrolytic capacitor that avoids the use of silver-containing solder, eliminates the need for long-time cleaning after plating, and reduces the number of man-hours.

FIG. 1 is a perspective view of an electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. The anode body 1 is made into a porous body by pressurizing, molding, and pre-sintering tantalum powder, which is a valve metal. In this embodiment, the shape is a rectangular parallelepiped, but it can also be formed into a cylindrical shape or a disk shape. A lead wire 2 is embedded in this anode body 1 and drawn out.

The lead wire 2 may be fixed to one side of the anode body 1 by welding.

This anode body 1 is connected to the lead fP as shown in FIG.
A large number of metal strips are held at regular intervals on the long strip metal plate '12, and in the subsequent steps, a large number of strip metal plates are processed at once in units of at least two long strip metal plates.

A dielectric oxide film is formed on the surface of the anode body 1 by anodization. This oxide film is not shown in the drawings. Next, a heat-resistant, electrically insulating, semiconductor rising prevention synthetic resin layer 3 is applied and formed on the end surface of the anode body 1 from which the lead wire 2 is drawn out. Thereafter, a manganese dioxide layer 4, which is a semiconductor layer, is formed on the surface of the anode body 1. The peripheral edge of the semiconductor layer 4 is in contact with the synthetic resin layer 3 for preventing semiconductor rising. In forming this semiconductor layer 4, the anode body is immersed in a manganese nitrate solution, and the impregnated manganese nitrate is thermally decomposed and converted into manganese dioxide. This operation is usually repeated several times to obtain the required thickness. The anode body 1 on which the semiconductor layer 4 is formed may be attached after repeating impregnation and thermal decomposition two to three times with the three synthetic resin layers.The first carbon coating is applied and dried. Then, the first carbon layer 5a is formed.

This first carbon layer 5a is sufficiently penetrated by the internal pressure of the porous semiconductor layer 4. Therefore, the semiconductor layer 4 and the first carbon layer 5a
It makes contact with the ferromagnetic material with low resistance, and the conductivity between the two is good.

A second carbon paint is further applied on the first carbon layer 5a and cured to form a second carbon layer 5b. The peripheries of these carbon layers 5a and 5b are in contact with the synthetic resin layer 3 for preventing semiconductor rise. The second carbon layer 5 b &; t has a composition that does not allow penetration of the later-described = coating solution. If the anode body having only the first carbon layer 5a is immersed in a plating solution, the plating solution will penetrate into the semiconductor layer 4 through the first carbon layer 5a, degrading the characteristics of the electrolytic capacitor. Become. In the present invention, since the second carbon layer ib is formed on the first carbon layer 5a, the plating solution is prevented from seeping into the semiconductor layer.

The first carbon layer 5a is obtained by coating and drying a mixture of graphite and a resin component as a binder dispersed in water. The @2 carbon layer 5b is made by applying a mixture of graphite and a heat-resistant resin component dispersed in a mortar solvent, and thermally curing it. Note that in the specification and drawings, the first and second carbon layers 5a, 51)
will be collectively represented by reference numeral 5.

The anode body on which the carbon layer 5 is formed is immersed in, for example, an electroless nickel plating solution, and the nickel plating layer 6 is formed thereon. When immersed in the nickel plating solution, the synthetic resin layer 3 for semiconductor outer shield IE is formed, and the second carbon layer 5b for the purpose of preventing penetration of the solution is formed in contact with it, so that the liquid level can be adjusted. It's extremely easy. Therefore, it is easy to work, and the plating layer can be uniformly formed on the carbon layer. In addition, since the plating solution is prevented from entering the semiconductor layer, there is no need to wash for a long time Pl- after plating. On the other hand, when using a conductive paint layer containing silver as in the prior art,
1. The silver particles should not be eaten into the solder, so to speak.
As a result, the electrical characteristics of the capacitor deteriorate.1-Hehe. ;,
In the present invention, which does not use a 17-electroconductive paint layer, such defective electrical characteristics do not occur.

Reel lt of the anode body 1 on which the nickel plating layer 6 is formed≦
! 2, the anode terminal piece 7 is fixed by welding or the like. In order to make the capacitor compact, the anode terminal piece 7 is moved close to the anode body 1 as long as there is no problem. After the anode terminal piece 7 is coated with solder, it becomes the connection part with the external circuit h")5, so the dimensions around it are determined so that it slightly protrudes from the plating layer of the anode body l. In the present embodiment, a plate-like body is illustrated as the anode terminal huff, but a body having a U-shaped cross section or a cap-shape may also be used as appropriate.

Next, an exterior synthetic resin layer 8 is formed to cover the cathode plating layer on the positive rod and to reinforce the anode body and anode terminal piece. The eight synthetic resin layers for the exterior cover the entire circumferential surface of the anode body 1, leaving a part of the plating layer 6 on the side opposite to the lead wire extraction surface, and the exterior covering the entire circumferential surface of the anode body 1, and In order to form the exterior synthetic resin layer 8, the anode body is immersed in a synthetic resin liquid and the adhering synthetic resin liquid is hardened by scraping it up. However, 1. Before immersion in the synthetic resin liquid, a resin-repellent substance is applied to a part of the plating layer to form a cathode layer. By doing this, it is possible to leave a part of the plating layer on which the synthetic resin does not adhere, and provide the synthetic resin layer in the necessary areas.In addition, In the same way as applying a resin-repellent substance to a portion of the nickel plating layer 6, the same substance is applied to the anode terminal piece 7, and the entire anode body 1, terminal piece 7, etc. are immersed in the synthetic resin liquid. Therefore, there is no need to strictly adjust the liquid level to prevent excess resin from adhering to the outside.Since the capacitor in which the present invention is preferably implemented is ultra-small, adjusting the liquid level requires only a few minutes. In other cases, it is difficult to do so, and the method described above, which does not require liquid level adjustment, is optimal.

The end face of the nickel plating layer 6 exposed from the exterior synthetic resin layer 8 is soldered to form a cathode terminal 9.

In addition, the anode terminal piece 7 is also soldered to the anode terminal 10.
form. These solder layers can be formed all at once by immersing the anode body 1 in flux and then immersing it in molten solder. Thereafter, after cleaning and the like, the lead wire 2 is cut off at the line XX in FIG. 2 to complete the capacitor.

In the embodiments described above, a nickel plating layer 6 was formed, but other metals such as copper may be plated.

A second embodiment of the invention is shown in FIG. FIG. 4 is a sectional view thereof. In the second embodiment, before forming the cathode terminal 9 in the first embodiment, the cathode terminal piece 1 is coated on the nickel plating layer 6.
1 is electrically connected. Cathode terminal piece 11
is the same size as the anode terminal piece 7. Thereafter, a terminal 9 similar to 1 (λ) is provided by soldering. Then, as in the first embodiment, the lead wire 2 is cut off along the line xx to complete the capacitor Z.

By doing so, the cathode terminals 9 and 10 can be finished to have the same size and shape, making it easy and reliable to attach them to the conductor circuit on the printed wiring board. The cathode terminal piece 11 may be connected at any time after the formation of the nickel plating layer 6 and before the formation of the cathode terminal 9.

The effects of the present invention are as follows. The manufacturing method according to the present invention does not require the use of expensive silver paint or silver-containing solder, and even when soldering the cathode, strict temperature and time conditions that are required for the silver paint layer are not required. t7 no longer requires management! However, when forming the gold powder plating layer, delicate adjustments to the plating liquid and long cleaning times after plating are no longer necessary.

As a result, the characteristics of the capacitor are more stable than before, and the cost of front cover materials and man-hours are reduced.

Next, an anode terminal piece is attached to the anode lead, and a resin-repellent substance is applied to the terminal piece and the cathode terminal piece attached to the cathode terminal forming end or the other end of the anode body.1.
In the manufacturing method of the present invention, which involves immersion in the exterior resin liquid, it is not necessary to finely adjust the exterior resin liquid level or the immersion depth. Charging and mechanical reinforcement of the anode terminal with resin can be performed at the same time, and in addition, the anode terminal and the cathode terminal can also be soldered at the same time. Since strict control and fine adjustment of temperature, time, liquid level, etc. are no longer necessary at each stage of the manufacturing method, everything from the formation of an anodized film on the surface of the anode body to the final anode and cathode terminals is eliminated. The entire process up to soldering can be done all at once, with multiple anode bodies attached to a long strip-shaped metal plate, without having to separate them midway through, greatly reducing the number of man-hours.

[Brief explanation of drawings]

The first figure is a perspective view of a chip capacitor according to the present invention. FIG. 2 is a sectional view thereof, FIG. 3 is a front view showing an anode body attached to a long strip-shaped metal plate, and FIG. 4 is a sectional view of another embodiment. DESCRIPTION OF SYMBOLS 1...Anode body, 2...Lead wire, 3...Semiconductor external shielding synthetic resin layer, 4...Semiconductor layer, 5a...First
Carbon layer, 51)... Second carbon layer, 6... Plating layer, 7... Positive If; l: jA element piece, 8... Synthetic resin layer for exterior, 9... Cathode terminal, 10... Anode terminal, 11... Cathode terminal piece, 12... Long strip metal plate agent Patent attorney Kei Nishi Department Figure 1 Figure 2 Figure 3 Figure 12 Figure 4

Claims (1)

[Claims] It is made of valve metal and has a lead +tll from one end surface! A number of anode bodies from which the lead wires have been drawn out are attached to a long strip-shaped metal plate, and after an anodic oxide film is formed on the surface of the anode body, a heat-resistant and electrical An insulating synthetic resin layer for preventing semiconductor build-up is formed, and then a semiconductor layer, a carbon layer, and a metal plating layer are formed on the anodic oxide film so that their peripheral edges are in contact with the synthetic resin layer for preventing semiconductor build-up. Then, the lead wire is filled with an anode end, and then a part of the metal plating layer on the end face opposite to the lead wire extraction end face of the anode body is left, and the remaining gold plated layer and the anode are filled. An exterior synthetic resin layer is provided between the body and the anode terminal piece in contact with the surface of the anode body side of the anode terminal piece, and the metal exposed from the anode terminal piece and the exterior synthetic resin layer is then immersed in molten solder. A method for manufacturing a chip-shaped solid electrolytic capacitor, characterized in that finishing the plating layer as an anode and a cathode terminal, respectively, is performed at least on one unit of the band-shaped metal plate.