JPH02280310A - Manufacture of electrode material for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To improve capacitance of a capacity by forming a Ti film by applying cathode are plasma deposit to a substrate surface under specified conditions. CONSTITUTION:When a Ti film is formed to a substrate surface to manufacture an electrode material of an electrolytic capacitor, the Ti film is formed to a substrate surface in a thickness of 0.1 to 1.6mum at a base pressure of 1X10<-4>Torr or below with arc discharge current of 60 to 120A without introducing reaction gas and inert gas by applying cathode arc plasma deposit method. That is, when a voltage is applied to an evaporation source 13 by an arc power source 17, arc spot moves on a surface of a metallic evaporation substance (cathode) 15, and the evaporation substance makes flash evaporation and is discharged from the evaporation source 13 to the substrate 1 to form a metallic film 2 on the substrate 1. A micro particle 21 which is discharged together with metallic atom and ion from the evaporation substrate 15 forms appropriate irregularities on a coat 2, thereby increasing capacitance of the electrode material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an electrode material for an electrolytic capacitor,
In particular, the present invention relates to a method of manufacturing an electrode material that can increase capacitance.

[Prior Art] As means for improving the performance of electrolytic capacitors, for example, Japanese Patent Laid-Open Nos. 59-167009, 61-1826,
Various techniques have been proposed, such as those seen in Japanese Patent Nos. 61-214420, and studies have been made to increase the capacitance of the i-electrode material itself.

An almost established idea for increasing the capacitance of electrode materials is to roughen the surface of the electrode material base material to increase the surface area, and then form a high dielectric film on that surface. It is said that if fine irregularities are formed on the surface of the high-talk telephone body film, the capacitance will further increase due to the enlargement of the surface area.

For example, in the technique disclosed in JP-A-61-214420, a vacuum evaporation method 1 an inert gas evaporation method, a sputtering method, an ion blating method, etc. are applied to the surface of a base material that has been roughened by an etching method. Forms a conductive metal film. According to this technique, as shown in FIG. 2, a metal film 2 is formed on the roughened surface 3 of the base material 1, and therefore a protrusion 5 is formed on this metal film III 2. The protrusion 5 has a diameter Rh, 02 to 1. Preferably, OAtmO is spherical. Then, the metal film 2 becomes an oxide film and becomes a highly conductive material, and the capacitance increases due to the above-mentioned shape characteristics.

[Problems to be Solved by the Invention] FIG. 3 is a schematic explanatory diagram showing an apparatus for carrying out an inert gas vapor deposition method, in which 10 is a vacuum vessel, 12 is a gas introduction pipe, and 13 is an evaporation source. , 14 represents an electron gun, and 15 represents an evaporated substance. The evaporated substance 15 (metallic substance) is heated by the electron beam emitted from the electron gun 14, evaporates, and adheres to the surface of the base material 1 to form the metal coating 2. The protrusion 5 is formed on the metal coating 2. In order to do this, it is essential to introduce an inert gas such as Ar through the gas introduction pipe 12. In other words, when the atmospheric pressure is low in the normal vapor deposition method, the film becomes smooth and dense and the effect of surface expansion is not exhibited. The protrusion 5 is formed to be effective in increasing the capacity. - In the vacuum evaporation method, sputtering method, and ion blating method for boat fishing, metal evaporates in an atomic state and flies to the surface of the base material, and a metal skin 11i 2 is formed on the surface of the base material. Since the form of the formed film is affected by the atmospheric pressure, it is essential to introduce an inert gas to properly adjust the atmospheric pressure.

As mentioned above, in the techniques proposed so far, introduction of an inert gas is essential no matter which film forming method is adopted. However, in order to obtain a preferable film form as shown in Fig. 2 using the various film forming methods described above, delicate adjustments are required in the pressure, tL amount, etc. of the inert gas, and the evaporation source and substrate Since the film form is also influenced by the distance between the two, there is a drawback that it is difficult to control the film forming conditions. Also, the cost of inert gas cannot be underestimated. Furthermore, the film with a porous columnar structure formed in this way has poor adhesion to the base material and has low strength, so the film can be damaged during the manufacture of electrolytic capacitors, which may affect the performance of the electrolytic capacitor. There is also the problem of causing a decline.

The present invention has been made to solve these technical problems, and its purpose is to develop an electrolytic material that can improve the capacitance of electrolytic capacitors without causing the above-mentioned disadvantages. The point is to provide a manufacturing method.

[Means for Solving the Problems] The present invention has achieved the above object by applying a cathodic arc plasma deposition method to produce an electrode material for an electrolytic capacitor by forming a Ti film on the surface of a base material. The base pressure was set to 1xlO-4 Torr or less, and the arc discharge flow was set to 80 to 120 A without introducing any reactive gas or inert gas, and a Ti film was applied to the base material surface to a thickness of 0.
．． This is a method for manufacturing an electrode material for an electrolytic capacitor, the gist of which is that it includes a step of forming an electrode material with a thickness of 1 to 1.0 μm.

[Function] The present invention is constructed as described above, but in short, it is possible to introduce either a reactive gas (this point will be described later) or an inert gas while setting the base pressure and arc discharge current within appropriate ranges. It has been discovered that if a Ti film is formed on a substrate by performing a cathodic arc plasma evaporation method without using a Ti film, an electrode material in the desired form can be obtained, and the present invention has now been completed.

The cathodic arc plasma deposition method is described in Japanese Patent Publication No. 58-30, for example.
It is a type of thin film forming method in vacuum known as the "arc deposition method" disclosed in No. It has the characteristic that it can be formed on top. This vapor deposition method is
TiN in a reactive gas atmosphere such as N2°CH4.

It is mainly used to form wear-resistant films, corrosion-resistant films, and decorative films made of compounds such as Tic, T1CN, ZrN, and CrN, and is especially widely applied as a coating technology for wear-resistant films on cutting tools. ing.

FIG. 4 is a schematic explanatory diagram showing a cathodic arc plasma deposition apparatus configured to carry out the present invention, and FIG. 5 is a principle diagram showing the state of evaporation. In the figure, 110, 13, and 15 are given the same reference numerals as in FIG. Particles are shown respectively.

When a voltage is applied to the evaporation source 13 by the arc power source 17, a cathode point (
The arc spot 19 moves around randomly, and the arc current concentrates on this cathode spot 19. The size of the cathode spot 19 is generally about 1 to 3 μmφ, and the current in this cathode spot 19 is about 10 A/μm 2 . As a result of such a large current density being concentrated at the cathode spot 19, the evaporated substance flash evaporates. This evaporated gas contains electrons, ions, neutral vapor atoms, particles of about 0.2 to 1.0 μm (hereinafter referred to as macroparticles), and the like. As shown in FIG. 4, the evaporated gas is emitted from the evaporation source 13 toward the base material 1, and is deposited on the surface of the base material 1. ff1j Finally, a metal film 2 is formed on the base material 1. A schematic diagram of the metal film 2 formed in this manner is shown in FIG. In addition, numeral 21 in the figure indicates a macroparticle. Further, the bias power supply is for applying a negative bias voltage to the base material 1 as necessary, and is effective for improving the adhesion of the metal coating 2 to the base material 1.

If the cathodic arc plasma deposition method is applied in this way and the metal skin 11M2 is formed on the surface of the base material 1 without introducing any reactive gas or inert gas, the metal skin 11M2 is released from the evaporated substance 15 together with metal atoms and ions. The macroparticles 21 form appropriate irregularities on the metal skin 1112, which contributes to an increase in the capacitance of the electrode material. Furthermore, since it is not necessary to introduce a reactive gas or an inert gas, the influence between the evaporation source 13 and the base material 1 is small, and the operation can be stabilized. Furthermore, the film formed by this method has sufficient adhesion and strength.

Originally, wear-resistant membrane, corrosion-resistant membrane and fiii fil
When forming a film, macroparticles of evaporated substances are considered to be undesirable as they cause non-uniformity of the film and deterioration of the surface roughness, and are considered to be a drawback of film formation by cathodic arc plasma deposition. Ta. Therefore, when forming the various films mentioned above using the cathodic arc plasma deposition method, it is common to introduce a reactive gas into the vacuum chamber 10 as shown in FIG. 3, thereby preventing the generation of macroparticles. The production of uniform membranes has been carried out that has significantly reduced the amount of heat and has no problem in practical use. The reason for this is that when a reactive gas is introduced, a film of reaction products such as TiN or TiC is formed on the surface of the metal evaporator (cathode).
Since these products have a higher melting point than the metal vaporized material, it is thought that melting at the cathode point (arc spot) is reduced and macroparticles are reduced.

The application of the cathodic arc plasma deposition method in the present invention is not based on the previously common practice of the method, but is based on a characteristic previously considered disadvantageous, namely, in the absence of reactive gases (or inert gases). It actively utilizes macroparticles that are easy to generate.

The reasons for limiting each requirement in the present invention are as follows.

First, the base pressure is I X 10-'To r r (0
, 013 Pa) or less. This is because when the base pressure exceeds 1xlO-4 Torr, the influence of residual gas present in the vacuum container on the film becomes significant.

In other words, reaction products of residual gas and Ti (e.g. TiN and Ti
02) is mixed into the film as an impurity, and the adhesion of the film is reduced due to residual gas adhering to the surface of the base material. Note that the base pressure here refers to the pressure at the start of evaporation, and as long as the base pressure is set to a predetermined value and rice is harvested, there is no need to introduce gas during film formation, so pressure control is unnecessary. It is.

Macro particles tend to increase as the arc discharge current increases, but in order to give the electrode material the desired shape and obtain the effect of increasing capacitance, the arc discharge current must be 8.
It needs to be 0A or more. However, when the arc discharge current reaches about 100 A, the increase in macroparticles reaches a saturated state, and when it further exceeds 120 A, the possibility that the cathode spot is divided into two or more increases, resulting in a decrease in capacitance.

According to the cathodic arc plasma deposition method, in addition to Ti, Ta
Although it is also possible to form a metal layer III 2 of metal such as Cu, Fe, etc., the present invention uses TiO2, which is produced by oxidation, because it has a high dielectric constant and is superior in durability and strength compared to other metals. Here, the metal film 2 formed on the base material 1 was limited to TI. Furthermore, the thickness of the metal film 2 does not have a large effect on the capacitance, but is 0.1
If it is less than 1.0 μm, variations in capacitance (effects of film thickness distribution) will appear, whereas if it exceeds 1.0 μm, the cost of the Ti target will increase, which is undesirable. Therefore, in the present invention, the thickness of the Ti film is set to 0.1 to 1.0 μm.

On the other hand, the base material 1 used in the present invention is not particularly limited as long as it can be any base material that has been used up to now, but aluminum foil whose surface has been etched is most commonly used. However, in addition to the conductive material, a non-conductive material can also be used for the base material. In other words, the electrical conductivity required for the electrode material is the metal layer 1i2 (Ti) on the surface of the base material 1.
The substrate 1 itself is not required to be electrically conductive.

The apparatus for carrying out the present invention is not limited to the batch type as shown in Fig. 4, but may be a roll coater type as shown in Fig. With this device, continuous formation of the metal coating 2 can be achieved while feeding the coiled base material 31 by the unwinding roll 321, the take-up roll 33, and the cooling roll 34, and productivity can be improved.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the following examples are not intended to limit the present invention.
Any design changes for the purposes described below are included within the technical scope of the present invention.

[Example] An aluminum foil whose surface had been etched was used as the base material 1, and various Ti films were formed on the base material 1 by changing the arc discharge current using the apparatus shown in FIG. The base pressure (residual gas) at this time is 5.5 x 10
-'Torr, no reaction gas or inert gas was introduced, and no bias voltage was applied.

When the capacitance of the obtained electrode material was measured, the results shown in Table 1 were obtained. In Table 1, as one of the comparative examples, examples (No. 1.4 to 6), a large capacitance was obtained in all cases.

[Effects of the Invention] As described above, according to the method of the present invention, an optimal electrode material for electrolytic capacitors could be realized without causing the disadvantages shown in the prior art.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a metal film 2 formed by the method of the present invention, Fig. 2 is a schematic diagram showing the form of a conventional metal film 2, and Fig. 3 is a schematic diagram showing the form of a conventional metal film 2. A schematic explanatory diagram showing the apparatus, FIG. 4 is a schematic explanatory diagram showing a cathodic arc plasma deposition apparatus configured to carry out the method of the present invention, and FIG. 5 is a principle showing the state of metal evaporation in the cathodic arc plasma deposition method. 6 are schematic explanatory diagrams showing other examples of a cathodic arc plasma deposition apparatus configured to carry out the method of the present invention. 1.31...Base material 2...Metal coating 10...
Vacuum container 13... Evaporation source 5... Evaporation substance
17...Arc power supply 8...Bias power supply 19.
...Cathode point 0...Anode 1...Macro particles

Claims (1)

[Claims] In manufacturing electrode materials for electrolytic capacitors by forming a Ti film on the surface of the base material, we apply cathodic arc plasma deposition, keep the base pressure to 1 x 10^-^4 Torr or less, and use reactive gas and inert gas. Manufacture of an electrode material for an electrolytic capacitor, characterized in that it includes a step of setting an arc discharge current to 80 to 120 A without introducing any of the above, and forming a Ti film with a thickness of 0.1 to 1.0 μm on the surface of a base material. Method.