JPH0463262A - Electrode foil for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To produce an electrode foil contributing to the miniaturization and increase in capacity of an electrolytic capacitor by forming a thin metallic film containing nitrogen on a substrate. CONSTITUTION:At the time of forming a thin film by vapor-depositing a metal onto a substrate by a vacuum deposition method, a nitrogen-containing gas is directed on the substrate at the prescribed angle of incidence to form a thin metallic film containing nitrogen. At this time, an Al or Co film is preferred as the thin metallic film, and it is preferable that nitrogen atoms are contained in the thin metallic film by 2-80% of the total number of metal atoms constituting the metallic foil film. Further, it is preferable that oxygen atoms in the surface layer of the thin metallic film are contained by 90-200% of the total number of metal atoms constituting the metallic foil film. By this method, the electrode foil material for electrolytic capacitor excellent in stability of characteristics and producing a marked effect of increasing electrostatic capacity can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrode foil for an electrolytic capacitor,
More specifically, the present invention relates to an electrode foil that contributes to increasing the size and capacity of electrolytic capacitors.

[Prior Art] As electrodes for electrolytic capacitors, aluminum foil is generally etched to enlarge its surface area. Increasing the surface area of the electrode is essential for increasing the capacitance of a capacitor, and the demand for smaller size and larger capacity demands further expansion of the surface area of the electrode. However, increasing the surface area of aluminum foil by etching is approaching its limit due to factors such as a decrease in the strength of the aluminum foil.

On the other hand, in Japanese Patent Application Laid-Open No. 56-29669, 30
It has been proposed to create an electrolytic capacitor electrode foil with an expanded surface area by creating a porous metal film by injecting the vapor of a valve metal such as aluminum or tantalum onto the substrate at an incident angle of 80 to 85 degrees or more, preferably 80 to 85 degrees. ing. Also, JP-A-59-
No. 167009 discloses that a valve metal such as aluminum, tantalum, titanium, niobium, or zirconium is deposited on a substrate such as aluminum foil in an inert gas such as argon to form a porous film and expand the surface area of the electrode. It has been proposed to increase the dielectric constant as well.

These techniques have a great effect on increasing the apparent capacitance per unit area of electrolytic capacitors.

[Problems to be Solved by the Invention] However, these techniques still have the following problems.

(1) In order to obtain a sufficient surface area expansion effect, it is necessary to increase the thickness of the valve metal film to 1 to 20 μm, which poses a problem in terms of productivity, and valve metals other than aluminum have high Since it is a melting point material, when attempting to form a relatively thick film as described above, the substrate is likely to be thermally damaged during vapor deposition, resulting in loss of flatness.

(2) In the method of vapor depositing valve metal in an inert gas, is it possible to obtain a larger surface area, that is, a larger capacitance, with the same film thickness by increasing the pressure in the vacuum chamber?On the other hand, if the pressure in the vacuum chamber is increased, There is a problem that the film deposition rate decreases. Particularly in large production machines that use straight electron beam guns, the evaporation source and the substrate cannot be placed very close to each other, so the film deposition rate decreases significantly as the pressure inside the vacuum chamber increases, resulting in a significant drop in productivity.

(3) Highly active porous metal films such as titanium and zirconium react with electrolytes and easily form hydrates and oxides, which tend to cause deterioration of capacitor characteristics.

The present invention was devised in view of the above-mentioned drawbacks of the prior art, and its objectives are to provide excellent stability of characteristics, a large effect in increasing capacitance, and to reduce the risk of heat damage during manufacturing. The object of the present invention is to provide an electrode foil material for electrolytic capacitors that has excellent productivity.

[Means for Solving the Problems] The object of the present invention is achieved by an electrode foil for an electrolytic capacitor, which is characterized in that a metal thin film containing nitrogen is formed on a base.

The metal thin film used in the present invention is preferably made of at least one metal selected from the group of so-called valve metals such as aluminum, titanium, zirconium, tantalum, niobium, and hafnium, or an alloy thereof, but cobalt, Metals such as chromium, nichrome, nickel, silver, copper, iron, zinc, and alloys thereof can also be used. However, in order to bring out the effects of the present invention significantly,
It is preferable to use a metal material that easily reacts with nitrogen to form nitrides, and from this point of view, valve metal and cobalt are suitable. Among these, aluminum and cobalt are preferable because they have relatively low melting points and can easily avoid heat damage to the substrate during production. Titanium is most preferable because it has a large effect on increasing capacitance.

Preferably, the metal thin film is created by evaporating metal using a vacuum evaporation method. Metal oxides and metal nitrides have high melting points, so when attempting to evaporate them to obtain a metal thin film, significant thermal damage often occurs to the substrate.

Furthermore, in the present invention, a metal thin film containing nitrogen means that nitrogen atoms are included in the metal atoms constituting the metal thin film.

The amount of nitrogen atoms contained in the metal atoms is not particularly limited, but in order to effectively achieve the object of the present invention, the amount of nitrogen atoms contained in the metal thin film should be 2% or more of the total number of metal atoms constituting the metal thin film. Preferably, it is contained in the metal thin film. The metal thin film preferably contains nitrogen atoms in an amount of 4% or more, more preferably 8% or more, and most preferably 15% or more of the total number of metal atoms constituting the metal thin film. It's good to be there. Further, it is preferable that the nitrogen atoms exist as a nitride of the metal element constituting the metal thin film from the viewpoint of stability of properties, and 1% or more of the metal atoms constituting the metal thin film are nitrogen atoms. It is desirable that the material be combined with the nitride to form a nitride. If there is too much nitride, it causes a decrease in dielectric constant and an increase in dielectric loss due to an increase in the resistance value of the metal thin film, so the atoms constituting the metal thin film that are bonded to nitrogen atoms are 80% or less. It is desirable that it be 70% or less, and even more desirable that it be 70% or less. The nitrogen atom content and the bonding state between metal atoms and nitrogen atoms can be determined by X-ray photoelectron spectroscopy.

In addition to nitrogen atoms in the surface layer of the metal thin film, oxygen atoms account for 90 to 200% of the total number of metal atoms constituting the metal thin film.
It is preferable that it is included. If the number of oxygen atoms is less than 90% of the total number of metal atoms constituting the metal thin film, it is undesirable because the dielectric loss will increase, and if it exceeds 200%, it will become overoxidized and the effect of containing nitrogen atoms. This is not desirable because it does not appear. It is more preferable that the number of oxygen atoms is 100 to 180% of the total number of metal atoms constituting the metal thin film, and 11-0% to 16%.
Most preferably, the content is 0%.

The content of oxygen atoms can be determined by X-ray photoelectron spectroscopy. In addition, the metal thin film surface layer in the present invention refers to the depth measured by a surface analysis method such as X-ray photoelectron spectroscopy without any particular etching, and is 30 to 60A from the surface.
The range is up to a depth of .

The thickness of the metal thin film should be selected within the range of 0.005 to 0.5 μm in order to suppress thermal damage to the substrate used, to reduce costs, and to increase capacitance. The thickness is preferably selected within the range of 0.01 to 0.4 μm, and more preferably within the range of 0.01 to 0.4 μm.

The nitrogen-containing metal thin film is formed on at least one side of the substrate, and the method for forming such a nitrogen-containing metal thin film on the substrate is as follows: An effective method is to direct a nitrogen-containing gas to the region of incidence of the metal vapor on the substrate. In order to make the effect of the electrode foil obtained by the present invention remarkable, it is preferable that the gas contains 10% or more of nitrogen;
It is more preferable that the content is 0% or more. Nitrogen or 50%
It is most preferable that the above is included. As the gas added to nitrogen, rare gases such as argon, neon, krypton, and helium, and hydrogen can be used. It is preferable to add a rare gas to the nitrogen to facilitate control of capacitance.

Adding a small amount of oxygen is preferable because it has the effect of reducing the grain size of the fine structure of the metal thin film and increasing the capacitance.

When the surface area of a sample with metal thin films formed on both sides is measured by the BET method, the specific surface area of the sample piece expressed as (actual surface area/apparent area) is preferably 150 to 600.

The nitrogen-containing gas can be supplied in a larger amount than a rare gas or the like because nitrogen is incorporated into the metal thin film. Therefore, the nitrogen-containing gas has a strong viscous flow property in the region where the vapor is incident on the substrate, causing uneven gas supply and eventually uneven properties of the metal thin film in the width and length directions. When supplying a gas containing nitrogen, it is preferable to arrange the supply nozzle so that these problems do not occur.

Hereinafter, a method for manufacturing an electrode foil according to the present invention will be outlined with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing one example of a vacuum evaporation apparatus. In the figure, 1 is a cylindrical drum for supporting, cooling, and running a long substrate, 2 is an evaporation source, and 3 and 4 are evaporation sources. This is a mask for restricting the vapor flow from the evaporation source to be incident on the substrate at a predetermined angle of incidence, and the range on the drum where the vapor flow from the evaporation source is incident on the substrate is limited by the masks 3 and 4. Refers to the area where metal vapor enters the substrate.

The distance between the masks 3 and 4 and the drum 1 is such that the vapor flow wraps around behind the mask, obscuring the initial and final incident angles, reducing the adhesion between the substrate and the thin film, and obscuring the surface structure of the thin film. A short length is better in order to prevent this, while a longer length is better in order to retain the inert gas directed to the region of incidence of the vapor onto the substrate.From these points, the distance between the mask ends 6 and 10 and the drum should be between 5 mm and 100 mm. The range is preferably from 10 mm to 60 mm, and more preferably from 10 mm to 60 mm.

To increase capacitance, the metal vapor is preferably incident on the substrate at specific initial and final angles of incidence. The angle of incidence of vapor onto the substrate will be explained below with reference to FIG.

A point 12 where a straight line 11 connecting the center 5 of the evaporation source and the downstream end 10 of the mask 3 in the substrate running direction enters the cylindrical drum (substrate)
Set the normal line 13 on the drum surface.

The angle β between the normal 13 and the straight line 11 is the initial angle of incidence. Depending on the positional relationship of the mask 3, drum 1, and evaporation source 2,
The initial incident angle may be on the upstream side or downstream of the normal line to the drum surface in the direction of substrate travel. Regarding the sign of the incident angle, when the angle formed by the normal line 13 and the straight line 11 is on the upstream side in the base body running direction, it is taken as a negative value, and when it is on the downstream side, it is taken as a positive value. A normal line 9 is set to the drum surface at a point 8 where a straight line 7 connecting the center 5 of the evaporation source and the upstream end 6 of the mask 4 in the substrate running direction enters the drum. The angle α formed by the normal line 8 and the straight line 7 is the final angle of incidence. Depending on the positional relationship between the mask 4, the drum 1, and the evaporation source 2, the final incident angle may be a negative value or a positive value.

In order to increase the capacitance of the electrode foil for an electrolytic capacitor of the present invention and to increase productivity, it is desirable that the initial angle of incidence and the final angle of incidence be set in a combination within a specific range. A combination of an initial incidence angle of 30 to 30 degrees and a final incidence angle of 190 to 45 degrees, and an initial incidence angle of 4
It is preferable to select a combination between 5 and 90 degrees and the final incident angle between 30 and 30 degrees. The initial angle of incidence is 130 to 30 degrees and the final angle of incidence is 85 to -50 degrees.
Even more preferred are combinations in which the initial angle of incidence is between 50 and 85 degrees and the final angle of incidence is between 130 and 30 degrees.

In order to effectively retain the directed nitrogen-containing gas, the region where the vapor enters the substrate is formed by an opening between the downstream end 10 of the mask 3 in the substrate traveling direction and the upstream end 6 of the mask 4 in the substrate traveling direction. It is preferable to have a substantially closed structure except for the following. That is, the region where the vapor enters the substrate is blocked from below by masks 3 and 4, from above by drum 1, and further by the first
Preferably, the sides are blocked off by a partition wall (not shown) that closes the space between the mask and the drum. The nitrogen-containing gas is supplied to the substantially sealed structure portion from the upstream side or the downstream side in the traveling direction of the substrate, or from both the upstream side and the downstream side toward the region where vapor enters the substrate through a nozzle.

Supplying the nitrogen-containing gas from a specific direction corresponding to the combination of the initial and final incident angles of the metal vapor onto the substrate increases capacitance, reduces dielectric loss, and This is preferable in terms of reducing changes in capacitance over time. When the initial incident angle is -30 to 30 degrees and the final incident angle is -90 to -45 degrees, the metal vapor enters the incident region of the substrate from the upstream or downstream side in the direction of movement of the substrate, or from the direction of movement of the substrate. Preferably, the nitrogen-containing gas is directed from both the upstream and downstream sides. In order to obtain as large a capacitance as possible while limiting the thickness of the metal thin film to, for example, less than 0.2 μm for the purpose of improving productivity and avoiding heat damage, it is necessary to It is preferable to direct the nitrogen-containing gas from the downstream side in the running direction, or to direct the nitrogen-containing gas from the upstream and downstream sides in the substrate running direction. When the initial incident angle is 45 to 90 degrees and the final incident angle is 130 to 30 degrees, it is preferable to direct the nitrogen-containing gas to the region of incidence of metal vapor on the substrate from the downstream side in the direction of movement of the substrate. .

There are no particular restrictions on the shape of the gas supply nozzle.
The nozzle length is preferably three times or more the nozzle diameter in order to give appropriate directionality to the ejected gas and direct it to the region where the vapor is incident on the substrate. Further, it is preferable that a plurality of nozzles be provided in the width direction of the drum in order to improve the uniformity of the formed thin film in the width direction.

As the substrate used in the present invention, in addition to aluminum foil, aluminum alloy foil, metal foil other than aluminum, plastic film, paper, etc. can also be used, but the substrate has low leakage current and high mechanical strength. From the point
Preferably, aluminum foil, aluminum alloy foil or plastic film is used. These metal foils are subjected to roughening treatments such as etching or sandblasting to increase the surface area, but the metal foils are substantially flat in that they can omit processes and increase productivity. It is preferable. Here, the term "substantially flat" means that there are no etched holes caused by chemical etching or the like, and there are no excessive irregularities caused by roughening or rolling scratches. When surface roughness is expressed in RMS, which is the average value of height differences between adjacent protrusions and valleys, it is preferably 0.03 μm or less.

The thickness of the metal foil is determined from the relationship between mechanical strength and occupied volume.
A range of ~100 μm is preferred.

Examples of materials for the plastic film include polyesters such as polyethylene terephthalate and polycarbonate, polyolefins such as polypropylene, polyarylene sulfides such as polyphenylene sulfide, polyamides, aromatic polyamides, polyether ketones, and polyimides. However, polyethylene terephthalate or polypropylene is preferred in terms of electrical properties and cost. In terms of mechanical stability and strength, these plastics are preferably biaxially stretched to form a film. The thickness of the plastic film is preferably in the range of 1 to 50 μm in view of the relationship between mechanical strength and occupied volume.

When the metal thin film of the present invention is formed on only one side of a non-conductive substrate such as a plastic film, it is necessary that the opposite side of the film be metallized. Metallization of plastic films is performed by forming a metal film by vapor deposition or sputtering. The metal film is preferably an aluminum film or a zinc film because the higher the conductivity, the lower the dielectric loss. The thickness of the metal film is preferably in the range of 0.03 to 0.15 μm, since the thicker the metal film, the better the conductivity, and the thinner the metal film, the easier it is to self-heal. The non-conductive substrate may be subjected to pre-treatment such as adhesion-facilitating treatment prior to metallization. Since titanium, zirconium, tantalum, niobium, hafnium, etc. are not highly conductive, if a film of these metals or alloys is to be formed on a non-conductive substrate, the non-conductive substrate must be metallized beforehand. This is preferable in that dielectric loss can be reduced.

Next, an example of the method for manufacturing an electrode foil for an electrolytic capacitor according to the present invention will be explained in more detail using a vacuum evaporation apparatus shown in FIG. 2, but of course the method is not limited thereto.

That is, FIG. 2 is a schematic cross-sectional view of a vacuum evaporation apparatus equipped with a long substrate traveling system, in which an unwinding shaft 15, an unwinding shaft 15,
A long substrate traveling system consisting of a cylindrical cooling drum 16 and a winding shaft 17 is installed.

18 is an aluminum foil base of a predetermined thickness. Vacuum chamber 1
4 is separated by a partition 22.23 and a mask 24.25 into an upper tank 19 containing an unwinding shaft and a winding shaft and a lower tank 20 containing an evaporation source 21, and exhaust ports 26 and 27. They are each evacuated. The mask 24 on the upstream side in the substrate running direction is installed so that the initial angle of incidence of vapor from the evaporation source onto the substrate is preferably a predetermined angle in the range of -30 to 30 degrees. Mask 2 on the downstream side in the base body running direction
5 is installed so that the final angle of incidence of vapor from the evaporation source onto the substrate is preferably a predetermined angle in the range of -90 to -45 degrees. 29.32 is a nozzle for supplying nitrogen-containing gas to the area where metal vapor enters the substrate, and its tip is:
As shown in the figure, it is preferably provided between the mask 24, 25 and the drum 16, so that the residue is ejected from a position that is preferably 50 mm or more, more preferably 70 mm or more away from the opening end of the mask. It is possible to effectively suppress characteristic unevenness in the width direction and length direction of the metal thin film due to uneven supply. 28.31
is a valve.

Now, in such a device, the inside of the lower tank is 5×1O-5T.
exhaust to below orr, open one valve 28 and nozzle 2
A gas containing nitrogen is directed from the downstream side in the substrate running direction to the steam injection area surrounded by the partition wall 22.23, mask 24.25, and cooling drum 16 through 9, and the pressure inside the lower tank is increased to 1X.
The pressure is adjusted to a predetermined pressure in the range of 10-' to 1×IQ-2 Torr. The evaporation source is an electron beam heater filled with titanium ingots 30.

While the base is running, a titanium ingot is melted and evaporated to deposit a titanium thin film of a predetermined thickness onto the base at a predetermined deposition rate. Similarly, a titanium thin film is deposited on the other side of the substrate. In this way, an electrode foil for an electrolytic capacitor is obtained.

Although induction heaters, resistance heaters, racer heaters, and the like can be used as the metal evaporation source, it is preferable to use an electron beam heater in order to evaporate high-melting point metals at high speed. It is permissible to perform ion blating by emitting high frequency power between these evaporation sources and the substrate as appropriate. Further, these evaporation sources do not need to be located directly below the drum, and may be appropriately selected from the viewpoint of material usage efficiency. Further, the substrate may be appropriately pretreated by a known method for purposes such as improving adhesive strength prior to forming the metal thin film.

[Effects of the Invention] Since the present invention uses a metal thin film containing nitrogen as an electrode foil for an electrolytic capacitor, a much larger capacitance can be obtained compared to conventional electrode foils. This makes it possible to maintain a desired level of capacitance even after heat treatment or long-term storage at high temperature and high humidity, which inevitably causes a decrease in capacitance. In particular, heat treatment of the cathode foil before device formation is highly effective in stabilizing capacitance, and the present invention is of great significance. Furthermore, since the metal thin film contains nitrogen, the present invention has the effect of improving corrosion resistance and suppressing a significant decrease in capacitance, and greatly contributes to stabilizing capacitor characteristics.

The present invention also provides an electrode foil for an electrolytic capacitor having a large capacitance in which a metal thin film is formed on a substrate, and in order to increase the specific surface area of the metal thin film and obtain a predetermined capacitance, the metal is deposited by vapor deposition. By using a gas containing nitrogen as the gas supplied into the tank, it is possible to maintain a lower internal pressure and supply a larger amount of gas than when using a rare gas such as argon gas. A larger capacitance was obtained using a metal thin film. Furthermore, it was possible to suppress the decrease in the film deposition rate due to the increase in the pressure inside the tank to a small extent. Due to these, the present invention has a remarkable effect on improving productivity and preventing heat damage to the substrate.

[Operation of the Invention] The details of the operation of the present invention are not clear or are speculated as follows.

When nitrogen atoms are incorporated into the metal thin film, the so-called pin effect prevents the atoms from moving, which is thought to have the effect of improving corrosion resistance and suppressing a decrease in capacitance.

In order to increase the specific surface area of the metal thin film and obtain a predetermined capacitance, when a gas containing nitrogen is used as the gas supplied during the vapor deposition of the metal, the nitrogen reacts with the metal atoms to form nitrides. Therefore, the metal vapor is taken into the metal thin film on the surface of the substrate and the surface of the structure inside the tank where it is incident, and is consumed. This consumption causes the evaporation source, electron beam irradiation path,
The flying path of evaporated particles and the amount of gas flowing into the vacuum exhaust system have been significantly reduced, and it seems that even if a large amount of gas is introduced than before, it is less likely to cause a decrease in the film deposition rate or scattering of the electron beam. .

[Methods for measuring and evaluating characteristics] (1) Method for measuring capacitance Cut out a sample with metal thin films formed on both sides of the substrate, and
The sample is sandwiched and fixed between two boulders with openings of 0 mm x 20 mm. That is, a 20 mm square area is exposed on both sides of the sample.

Prepare two samples fixed in the holder in this way,
The sample was fixed in parallel in an electrolytic solution of 10% by weight ammonium borate aqueous solution.

Using two samples as electrodes, use an LCR meter (Ando Electric)
The capacitance at 100 Hz (7) was measured using AG-4311 (manufactured by Co., Ltd.). One half of the measured value was taken as the capacitance per unit area.

(2) Measurement of nitrogen in metal thin films Since a natural oxide film is formed on the outermost layer of a metal thin film, about 250 people were etched using ion etching to remove the natural oxide film, and then X-ray photoelectron spectroscopy was performed. (SSX
-100-206 (manufactured by SSI)), composition analysis and nitride detection were performed. The percentage of nitrogen atoms incorporated into the total metal atoms constituting the metal thin film was measured.

(3) Measurement of oxygen in the surface layer of the metal thin film The composition of the metal thin film was analyzed from the surface using an X-ray photoelectron spectrometer (SSK-100-206 (manufactured by SSI)) without etching. The percentage of oxygen atoms incorporated into the total metal atoms constituting the metal thin film was measured.

(4) Measurement of surface roughness The surface roughness of the substrate was measured using a universal surface profile measuring instrument (ET-10 manufactured by Kosaka Institute). The surface roughness is expressed in RMS, which is the average value of height differences between adjacent protrusions and valleys. Metal foil usually has streaks in the rolling direction, and its surface roughness also has directionality. At this time, measurements were taken in both the length direction and the width direction of the substrate, and the coarser measured value was adopted. Since there is almost no difference in the measured value whether the surface roughness of the substrate is measured from above the metal thin film or directly from the substrate, the surface roughness may be measured before or after the formation of the metal foil film.

[Examples] The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Example 1 A vacuum evaporation apparatus equipped with a long substrate transport system shown in FIG.
A substantially flat elongated aluminum foil substrate with a surface roughness of 2 μm and 0.02 μm was mounted.

Adjust the masks 24 and 25 so that the initial angle of incidence is 0 degrees,
The final angle of incidence was set to 152 degrees.

Further, the distance between the end of the mask opening and the drum was 30 mm. After filling the electron beam heater 21 with titanium ingots 30, the inside of the vacuum chamber 14 is evacuated through the exhaust ports 26 and 27, and the lower chamber 20 is separated by a partition wall 22, 23, a mask 24, 25, and a cooling drum 16. Internal pressure 5X10-
The pressure was set to 5 Torr or less. Next, valve 31 and nozzle 3
Nitrogen gas is supplied at 0°31/min through 2 toward the region where the vapor enters the substrate, and the pressure inside the lower tank is set to 3X10-'Tor.
Adjusted to r. While the substrate is running, a titanium ingot is melted and evaporated onto an aluminum foil to a thickness of 0.5 μm at a deposition rate of 2.5 μm/min. A titanium thin film of 1 μm was formed. When forming a titanium thin film, the cooling drum 16 is heated to -20°C.
It was cooled to Similarly, a titanium thin film was formed on the other side of the aluminum foil substrate.

The obtained electrode foil for an electrolytic capacitor had almost no deformation due to heat and had good flatness. The capacitance is 178
A very large value of 7 μF/cm2 was obtained. In the case of only aluminum foil as the base, the capacitance is 5.3μF/
cm2. Nitrogen atoms were incorporated at 47% of titanium atoms. Titanium nitride was detected from the titanium vapor deposited film. In the surface layer of the metal thin film, oxygen atoms are 13 atoms of titanium atoms.
0% was taken in.

Example 2 Nitrogen gas is supplied at 0.51/min, and the pressure inside the lower tank is set to 5×10
An electrode foil for an electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature was adjusted to -'Torr.

The obtained electrode foil for an electrolytic capacitor had almost no deformation due to heat and had good flatness. The capacitance is 298
A very large value of 8 μF/cm2 was obtained. Nitrogen atoms were incorporated at 63% of titanium atoms. Titanium nitride was detected from the titanium vapor deposited film. In the surface layer of the metal thin film, 123% of oxygen atoms or titanium atoms were incorporated.

Example 3 Nitrogen gas is supplied at 0.21/min, and the pressure inside the lower tank is set to 7×10
Electrode foil for an electrolytic capacitor was prepared in the same manner as in Example 1, except that the electron beam heater was filled with aluminum ingots instead of titanium ingots to form an aluminum thin film with a thickness of 0.3 μm. Created.

The obtained electrode foil for an electrolytic capacitor had almost no deformation due to heat and had good flatness. The capacitance is 105
μF/cm2, which is larger than that of Comparative Example 3, which will be described later.

Comparative Example 1 0.17 argon gas instead of nitrogen! /minute supply,
An electrode foil for an electrolytic capacitor was produced in the same manner as in Example 1 except that the pressure inside the lower tank was adjusted to 1X10-3 Torr.

The obtained electrode foil for electrolytic capacitors had almost no deformation due to heat, had good flatness, and had a capacitance of 22
It was 2μF/Cm2.

Comparative Example 2 An attempt was made to create an electrode foil for an electrolytic capacitor in the same manner as Comparative Example 1 except that argon gas was supplied for 0.211 minutes, but due to the rise in pressure inside the lower tank, the film deposition rate was extremely reduced. However, no titanium-deposited film was obtained.

Comparative Example 3 An electrode foil for an electrolytic capacitor was produced in the same manner as in Example 3, except that argon gas was supplied at 0.14'/min instead of nitrogen gas and the pressure inside the lower tank was adjusted to lXl0-3 Torr. .

The obtained electrode foil for electrolytic capacitors showed almost no deformation due to heat and had good flatness, but the capacitance was 27.
It was as small as μF/cm2.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views each showing an example of a vacuum evaporation apparatus for manufacturing an electrode foil for an electrolytic capacitor according to the present invention. α is the final incidence angle, β is the initial incidence angle, 2 is the evaporation source, 3.4
18 is a mask, 21 is an evaporation source, 28.31 is a gas supply valve, and 29.32 is a nozzle.

Claims (1)

[Claims] 1. An electrode foil for an electrolytic capacitor, comprising a thin metal film containing nitrogen formed on a substrate. 2. The electrode foil for an electrolytic capacitor according to claim 1, wherein the metal thin film contains nitrogen atoms in an amount of 2 to 80% of the total number of metal atoms constituting the metal foil film. 3. The electrode foil for an electrolytic capacitor according to claim 2, wherein the surface layer of the metal thin film contains oxygen atoms in an amount of 90 to 200% of the total number of metal atoms constituting the metal foil film. 4. The electrode foil for an electrolytic capacitor according to claim 1, wherein the substrate is substantially flat. 5. The electrode foil for an electrolytic capacitor according to claim 1, wherein the metal atoms constituting the metal thin film are mainly composed of aluminum or cobalt.