JPS6058575B2 - Manufacturing method of solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid electrolytic capacitor, and particularly to a method for manufacturing a non-polar solid electrolytic capacitor.

Conventionally, non-polarized electrolytic capacitors have been made by connecting two polar electrolytic capacitors in series to make them non-polar, but this connection type involves connecting independent electrolytic capacitors in series via lead wires. There are cases in which cases are fixedly connected in series instead of lead wires, and cases in which two electrolytic capacitor elements connected in series are enclosed in one case.

Although these devices have different connection means, they are composed of two independent electrolytic capacitor elements, so
The configuration of the electrolytic capacitor element and its electrical connection or integration must be performed separately; the process is an important part of the manufacturing process and causes high costs; and They have drawbacks such as difficulty in combination, resulting in variations in capacitance due to the structure, variations in characteristics and low reliability, and increase in size due to the coexistence of separate and independent electrolytic capacitor elements.

Moreover, if a non-polar electrolytic capacitor constructed in this manner is made leadless to enable face bonding (direct attachment), the terminal structure will become complicated. In addition, although non-polar solid electrolytic capacitors have been proposed in the past, conventional capacitors have had disadvantages such as complicated manufacturing processes and unsuitability for mass production of capacitors with uniform characteristics.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a non-polar solid electrolytic capacitor that has stable characteristics, high reliability, and no variation in capacitance.

That is, the present invention includes a step of forming a columnar electrode body, a step of uniformly laminating an oxide film, a cathode layer, and a metal layer on the surface of the electrode body, the metal layer, the cathode layer,
A step of cutting a part of the electrode body together with the oxide film at a specific interval to form an insulation gap, and a step of cutting the electrode body at a specific interval across the insulation gap to form an electrolytic capacitor piece. This is a manufacturing method consisting of:

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 1 shows a nonpolar solid electrolytic capacitor manufactured by the solid electrolytic capacitor manufacturing method of the present invention.

As shown in FIG. 1, the columnar electrode body 2 that becomes the anode is
This is a porous element body formed by vacuum combustion of tantalum powder, and two electrolytic capacitor elements 6A are mounted on the surface of this electrode element body 2 with an insulating gap 4 formed in the middle part in the longitudinal direction.
, 6B are formed.

Each electrolytic capacitor element 6A, 6B includes the electrode element body 2 as a common anode, and is composed of a laminated oxide film 8, a semiconductor layer 10, a graphite layer 12, and a metal layer 14,
A solder layer is formed on the surface of each metal layer 14 to connect terminal portions 16A and 1.
6B is formed so that face bonding is possible. The oxide film 8 is formed by immersing the electrode body 2 in an acid such as sulfuric acid and performing electrolytic oxidation using the electrode body 2 as an anode, and the semiconductor layer 10 is formed by adhering manganese dioxide (MrO2) to the upper surface of the oxide film 8. It is formed by letting. Graphite is applied to the upper surface of this semiconductor layer 10 to form a graphite layer 12, and a metal layer 14 such as silver is formed on the upper surface of this graphite layer 12. A recess 18 having the same width as the insulating gap 4 is formed in the electrode element 2, and an insulating layer 20 is formed with an insulating material inserted into the recess 18 and the insulating gap 4, and the two electrolytic capacitor elements 6A , 6B are electrically isolated.

Furthermore, the electrode element. Body 2 and electrolytic capacitor element 6A
, 6B are formed with an insulating film 22 to protect the end surfaces and prevent deterioration of electrical characteristics. In such a solid electrolytic capacitor, the electrolytic capacitor element 6A
, 6B uses a common electrode element body 2! As a result,
It is configured as a non-polar capacitor given by the equivalent circuit shown in FIG.

Since the two electrolytic capacitor elements 6A and 6B share the electrode body 2 and are electrically connected and mechanically integrated, the structure is extremely simple, robust, and compact. It's getting old. In particular, since electrical connections are made in an integrated manner without any connection means such as soldering, the characteristics are stable and the reliability is improved compared to conventional ones. Moreover, the capacitance value can be reduced even after the product is manufactured by enlarging the insulation gap 4, which is convenient in practice. Further, when mounting on a circuit board, face bonding can be performed on the wiring board using connection terminal portions 16A, 16B integrally formed on the surface of the electrolytic capacitor elements 6A, 6B, and a strong electrical connection can be obtained.

Although the electrode body 2 in this embodiment is made of tantalum, other anode metals such as aluminum can be used for the electrode body 2.

When the electrode body 2 is made of tantalum as in this embodiment, the advantages of tantalum are utilized and a solid electrolytic capacitor with good characteristics can be obtained. Next, a method for manufacturing a solid electrolytic capacitor according to the present invention will be explained in accordance with the manufacturing process with reference to FIG.

Step 1 As shown in A of FIG. 4, a cylindrical electrode body 2 is formed.

That is, the porous electrode body 2 can be obtained by pressure-forming tantalum powder into a cylindrical shape using a mold and then sintering it in a vacuum. Step (2) Using the electrode body 2 produced in Step 1, as shown in FIG. 4B, an electrolytic capacitor element 6 is uniformly formed.

To form this electrolytic capacitor element 6, first, the electrode body 2 is immersed in an acid such as ammonium borate or sulfuric acid, and electrolytic oxidation is performed using the electrode body 2 as an anode to form a dielectric material on the surface of the electrode body 2. An oxide film 8 is formed. This oxide film 8
After forming, the electrode body 2 is immersed in a manganese nitrate solution and thermally decomposed to form a semiconductor layer 10 made of a manganese dioxide layer on the surface of the oxide film 8. The electrode body 2 that has been surface-treated in this way is immersed in an aqueous graphite solution (AQUA DAC) to form a graphite layer 12 on the surface of the semiconductor layer 10, and then silver or the like is further deposited on the surface of the graphite layer 12. A metal layer 14 that will become a cathode is formed by et al. That is, after forming an oxide film 8 as a dielectric on the surface of the electrode element 2, a semiconductor layer 10, a graphite layer 12, and a metal layer 14 are laminated to form a cathode layer, and a cathode layer is formed on the surface of the metal layer 14. Forms a solder layer 16 that becomes connection terminal portions 16A and 16B for face bonding. Step 2 Next, as shown in FIG.
The cathode layer 2 and the metal layer 14, the solder layer 16, and a part of the surface layer of the electrode body 2 are cut at specific intervals to form an insulating gap 4.

The width of the insulation gap 4 is determined in consideration of the capacitance size, characteristics, etc. Step (2) Next, the electrolytic capacitor element 6 is cut along the broken lines A, b, and c in FIG. 4C to form electrolytic capacitor pieces.

The cutting interval is set so that the electrolytic capacitor elements 6A and 6B have the same width on both sides with the insulation gap 4 in between.
The width of the electrolytic capacitor elements 6A, 6B can be arbitrarily set depending on the required capacity. For example, if the insulating gaps 4 are formed at equal intervals, by alternating the cutting intervals, pieces of electrolytic capacitors with large and small capacitances can be obtained alternately. Further, when the cutting intervals are set to be equal, the capacitance can be changed by changing the width of the insulation gap 4 in the step (3). D in FIG. 4 shows a non-polar electrolytic capacitor piece 60 obtained by cutting. A capacitor piece 60 is obtained. Step V Next, after cutting the electrolytic capacitor piece 60 obtained in step (2) and surface treating the cut surface, in this example, an insulating material is applied to the insulating gap 4 as shown in E of FIG. is inserted to form an insulating layer 20, and an insulating film 22 is formed on the end face of the electrolytic capacitor piece 60.

In addition, for convenience of face bonding of the connection terminal parts 16A, 16B, the surface of the insulating layer 20 is attached to the connection terminal parts 16A, 16B.
It is formed to be recessed from the surface of 6B. Through the manufacturing steps 1 to 2 described above, a non-polar electrolytic capacitor can be easily obtained, and there is no need for the electrical connections required in the past.

In addition, since the electrolytic capacitor elements 6A and 6B are processed from the electrolytic capacitor element 6 that is uniformly formed under certain conditions, variations in composition are suppressed as much as possible, the characteristics are stable, and there is no variation in capacitance. You can get something. especially,
Since the capacitance can be determined by dimensional setting after the electrolytic capacitor element 6 is formed, uniform capacitance can be achieved. Furthermore, in forming the electrolytic capacitor piece 60, material loss is extremely small and yield is improved, leading to cost reduction.

Further, in the example, the insulating layer 20 was formed in the insulating gap 4 in step V, but even if the surface treatment is performed after forming the insulating gap 4 in step 2, and the insulating layer 20 is formed at this point, the same Effects can be obtained.

Furthermore, if a hollow body as shown in FIG. 3 is used for the electrode body 2, the amount of material can be saved, which is extremely effective when using expensive materials such as tantalum. Note that even if the electrode body 2 is replaced with the hollow electrode body 2A shown in FIG. 3, a nonpolar electrolytic capacitor similar to that of the above embodiment can be obtained.

In this case, the insulating film 22 is also hollow like the electrode body 2A. By configuring the electrode body 2A and the insulating film 22 to be hollow in this way, the cooling effect of the electrolytic capacitors 6A and 6B is enhanced, so that the temperature characteristics are improved. As explained above, according to the present invention, the following effects can be obtained.

(a) A non-polar electrolytic capacitor that has stable characteristics, is highly reliable, and can be face bonded can be easily obtained.

(b) Manufactured electrolytic capacitors are uniformly formed under certain conditions and then cut, so there is no variation in composition and it is possible to mass produce capacitors with uniform capacitance. can.

(C) Since the capacitance can be determined by the dimensions, the desired capacitance can be easily set and the capacitance can be made uniform. Moreover, the capacitance can be reduced by enlarging the insulation gap after manufacturing. can.

(d) There is extremely little material loss during manufacturing, improving yield and reducing costs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a solid electrolytic capacitor according to the method of manufacturing a solid electrolytic capacitor of the present invention, Fig. 2 is an explanatory diagram showing its equivalent circuit, and Fig. 3 is a method of manufacturing a solid electrolytic capacitor of the present invention. FIG. 4 is an explanatory diagram showing an embodiment of the method for manufacturing a solid electrolytic capacitor of the present invention. 2... Electrode element body, 4... Insulation gap, 6
, 6A, 6B... electrolytic capacitor element, 8...
...Oxide film, 10...Semiconductor layer, 12...
...graphite layer, 14...metal layer, 20
...Insulating layer, 60... Electrolytic capacitor piece.

Claims (1)

[Scope of Claims] 1. A step of forming a columnar electrode body, a step of uniformly laminating an oxide film, a cathode layer, and a metal layer on the surface of the electrode body, the metal layer, the cathode layer, A step of cutting a part of the electrode body together with the oxide film at a specific interval to form an insulation gap, and a step of cutting the electrode body at a specific interval across the insulation gap to form an electrolytic capacitor piece. A method for manufacturing a solid electrolytic capacitor, comprising: 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, further comprising the step of inserting an insulating material into the insulating gap to form an insulating layer.