WO2011099260A1 - 電極箔とその製造方法、電極箔を用いたコンデンサ - Google Patents
電極箔とその製造方法、電極箔を用いたコンデンサ Download PDFInfo
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- WO2011099260A1 WO2011099260A1 PCT/JP2011/000659 JP2011000659W WO2011099260A1 WO 2011099260 A1 WO2011099260 A1 WO 2011099260A1 JP 2011000659 W JP2011000659 W JP 2011000659W WO 2011099260 A1 WO2011099260 A1 WO 2011099260A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/0029—Processes of manufacture
- H01G9/0032—Processes of manufacture formation of the dielectric layer
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/008—Terminals
- H01G9/012—Terminals specially adapted for solid capacitors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/07—Dielectric layers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to an electrode foil, a manufacturing method thereof, and a capacitor using the electrode foil.
- Capacitors include low ESR solid electrolytic capacitors and high withstand voltage aluminum electrolytic capacitors. Solid electrolytic capacitors are used around CPUs of personal computers, and aluminum electrolytic capacitors are used as inverter power supplies for large equipment and inverter power supplies for automobiles such as hybrid cars. These capacitors are strongly desired to be small and large.
- a conventional solid electrolytic capacitor uses a foil whose surface is roughened by etching or vapor deposition as an anode and an electrode foil in which a dielectric film made of an oxide film is formed on the surface of the foil (for example, Patent Documents 1 and 2).
- the dielectric film is formed by anodic oxidation of the foil. That is, since the dielectric film is composed of a metal oxide constituting the foil, the dielectric constant and withstand voltage are affected by the material of the foil. Therefore, the degree of freedom is small in the design for increasing the dielectric constant or reducing the film thickness. Therefore, there is a limit to increasing the capacity of the capacitor.
- the present invention is an electrode foil for forming a large-capacity capacitor, a manufacturing method thereof, and a capacitor using the electrode foil.
- the electrode foil of the present invention has a foil having a metal layer on the surface, a first dielectric film formed on the metal layer, and a second dielectric film formed on the first dielectric film.
- the first dielectric film is made of a metal oxide constituting the metal layer, and has a thickness greater than 0 nm and less than 10 nm.
- the second dielectric film is mainly composed of a metal compound different from the first dielectric film.
- the first dielectric film is thinly formed to be less than 10 nm.
- the second dielectric film can easily increase the dielectric constant of the entire dielectric film or reduce the film thickness of the entire dielectric film. As a result, the capacity of the capacitor can be increased by using the electrode foil having this configuration.
- FIG. 1 is a perspective view of a capacitor according to Embodiment 1 of the present invention.
- FIG. 2A is a plan view of a capacitor element used in the capacitor shown in FIG. 2B is a cross-sectional view of the capacitor element shown in FIG. 2A.
- FIG. 3A is a schematic cross-sectional view showing the structure of the electrode foil according to Embodiment 1 of the present invention.
- FIG. 3B is an enlarged cross-sectional view of a portion 3B in FIG. 3A.
- 4A is a view showing an SEM image obtained by enlarging the electrode foil shown in FIG. 3A by 30,000 times.
- FIG. 4B is a schematic diagram of FIG. 4A.
- FIG. 5A is a diagram showing the relationship between the temperature of the plating solution and the capacitance of the electrode foil in Embodiment 1 of the present invention.
- FIG. 5B is a diagram showing a relationship between the temperature of the plating solution and the thickness of the first dielectric film in the first exemplary embodiment of the present invention.
- FIG. 6 is a partially cutaway perspective view of the capacitor according to Embodiment 2 of the present invention.
- the capacitor of the present embodiment is a solid electrolytic capacitor using a conductive polymer material as an electrolyte.
- FIG. 1 is a perspective view of a capacitor 7 in the present embodiment in which capacitor elements 6 are laminated.
- 2A is a plan view of the capacitor element 6, and
- FIG. 2B is a cross-sectional view of the capacitor element 6 taken along line 2B-2B.
- the flat capacitor element 6 includes an anode part 10, an insulating resist part (separation part) 11, and a cathode part 12.
- an electrode foil 9A having a dielectric film 8 formed on the surface is used as an anode foil. That is, the electrode foil 9A has the foil 9B and the dielectric film 8 formed on the rough film layer 19 of the foil 9B.
- the foil 9 ⁇ / b> B is formed of a base material 18 and a rough film layer 19 formed on the base material 18.
- the resist part 11 is formed on the electrode foil 9A, and the electrode foil 9A is separated into an anode part 10 and a cathode forming part (not shown).
- the anode part 10 is an exposed part of the base material 18 of the electrode foil 9A.
- the cathode portion 12 is formed on the dielectric film 8 in the cathode forming portion.
- the cathode portion 12 includes a solid electrolyte layer 13 made of a conductive polymer formed on the dielectric film 8, and a cathode layer 14 made of a carbon layer and a silver paste layer formed on the solid electrolyte layer 13. Yes.
- the capacitor 7 includes a plurality of capacitor elements 6, an anode terminal 15, a cathode terminal 16, and an exterior body 17.
- a plurality of capacitor elements 6 are laminated, and each anode portion 10 is connected to an anode terminal 15 by laser welding.
- a cathode terminal 16 is connected to the bottom surface or side surface of each cathode portion 12. More specifically, the cathode terminal 16 is formed with a bent portion 16A in which both side surfaces of the mounting portion of the capacitor element 6 are bent upward.
- the element mounting portion of the cathode terminal 16 and the cathode portion 12 of the lowermost capacitor element 6 are joined by a conductive adhesive.
- the bent portion 16A and the cathode portion 12 and the cathode portions 12 of the two capacitor elements 6 adjacent to each other in the vertical direction are also joined by a conductive adhesive.
- the anode terminal 15 and the cathode terminal 16 are integrally covered with an exterior body 17 made of an insulating resin together with the plurality of capacitor elements 6 in a state where a part of each of the anode terminal 15 and the cathode terminal 16 is exposed on the outer surface. A part of the anode terminal 15 and the cathode terminal 16 exposed from the exterior body 17 is bent along the exterior body 17 to the bottom surface. By this processing, a surface mount type capacitor 7 having an anode terminal and a cathode terminal on the bottom surface is formed.
- FIG. 3A is a schematic cross-sectional view of the electrode foil 9A
- FIG. 3B is an enlarged cross-sectional view of the 3B portion of FIG. 3A
- 4A is a view showing an SEM image obtained by enlarging the electrode foil 9A shown in FIG. 3A by 30,000 times
- FIG. 4B is a schematic view of FIG. 4A.
- the rough film layer 19 is formed such that a plurality of metal fine particles 20 are irregularly connected and extended from the surface of the substrate 18, and is branched into a plurality of branches. Consists of the body. In addition, a large number of pores exist inside the rough film layer 19. Since these holes are connected to the outside, the surface area of the rough film layer 19 is increased by these holes.
- the particle diameters of the metal fine particles 20 may be substantially the same, or the coarse film layer 19 may be formed by randomly laminating metal fine particles 20 having different particle diameters.
- the particle size of the metal fine particles 20 at the root portion may be increased and the particle size of the metal fine particles 20 at the tip portion may be decreased. With this configuration, it is possible to improve the adhesion between the metal fine particles 20 and the base material 18, maintain a large surface area, and realize a large capacity.
- an aluminum foil is used as the substrate 18, and the metal fine particles 20 are also mainly composed of aluminum.
- the dielectric film 8 is laminated on the outer surface of the metal fine particles 20 along the surface shape of the metal fine particles 20.
- the dielectric film 8 is composed of a laminated body of a first dielectric film 8A and a second dielectric film 8B formed on the first dielectric film 8A.
- the connection part 21 of the some metal fine particle 20 is bundled, the 1st dielectric film 8A and the 2nd dielectric film 8B are also formed in the outer periphery of this bundled connection part 21.
- the first dielectric film 8A is made of aluminum oxide which is an oxide of the metal fine particles 20, and the second dielectric film 8B has a metal compound different from that of the first dielectric film 8A as a main component.
- the second dielectric film 8B is made of titanium dioxide having a dielectric constant higher than that of the first dielectric film 8A. Therefore, the capacitance of the capacitor can be increased even if the overall film thickness is substantially the same as that of the dielectric film 8 composed of only the first dielectric film 8A made of aluminum oxide.
- the thickness of the first dielectric film 8A is greater than 0 nm and less than 10 nm.
- the second dielectric film 8B is preferably thicker than the first dielectric film 8A. Thereby, the thin first dielectric film 8A can be reinforced. Further, since the capacitance of the capacitor can be substantially increased by the second dielectric film 8B, the first dielectric film 8A is preferably as thin as possible. Specifically, it may be less than 10 nm.
- the first dielectric film 8A plays a role of connecting the metal fine particles 20 and the second dielectric film 8B, such as improving the adhesion between the metal fine particles 20 and the second dielectric film 8B.
- the metal fine particles 20 may be formed of a valve metal such as an aluminum alloy, titanium, niobium, or tantalum in addition to the aluminum.
- a valve metal such as an aluminum alloy, titanium, niobium, or tantalum in addition to the aluminum.
- the productivity when forming the coarse film layer 19 by vapor deposition is excellent.
- the base material 18 may be made of a metal material such as an aluminum alloy, tantalum, or titanium, or may be a film made of a conductive polymer, or transparent conductive glass, in addition to being made of aluminum.
- the rough film layer 19 composed of the metal fine particles 20 and the main component of the base material 18 may be different from each other. However, by using the same metal, the base material 18 is appropriately softened by heat at the time of vapor deposition, Bonding with the metal fine particles 20 is strengthened while maintaining the shape of the material 18.
- some of the metal fine particles 20 may be composed of a metal compound such as a metal oxide or a metal nitride. Furthermore, a part of each metal fine particle 20 may be comprised with metal compounds, such as a metal oxide or a metal nitride.
- the second dielectric film 8B can be formed of a material mainly composed of a metal compound different from the first dielectric film 8A.
- the dielectric constant of the second dielectric film 8B may be lower than that of the first dielectric film 8A.
- the second dielectric film 8B is formed of a metal compound capable of forming a thin film such as silicon dioxide, the thickness of the dielectric film 8 can be reduced, which contributes to an increase in the capacity of the entire capacitor.
- the rough film layer 19 is formed by vacuum vapor deposition with aluminum disposed in the vapor deposition source.
- the metal fine particles 20 of the rough film layer 19 preferably have an average particle diameter of 0.01 ⁇ m or more and 0.30 ⁇ m or less. That is, it is preferable to set the vacuum deposition conditions so that the average particle diameter of the metal fine particles 20 falls within the above range. Specifically, the average particle diameter of the metal fine particles 20 can be set within the above range by appropriately setting conditions such as the partial pressure of the introduced gas, the pressure during film formation, and the substrate temperature.
- metal fine particles 20 of about 0.10 ⁇ m are used.
- the connection part 21 of the metal fine particles 20 may be extremely thin and the mechanical strength may be weakened. If it exceeds 0.30 ⁇ m, it is difficult to increase the surface area.
- the diameter of the connecting portion 21 is preferably 30% or more of the particle diameter of the metal fine particles 20.
- the mode value of the pore diameter of the coarse film layer 19 is 0.01 ⁇ m or more and 0.20 ⁇ m or less.
- the surface area can be greatly enlarged.
- This mode value is extremely fine compared to the mode value of the hole diameter of the electrode foil roughened by normal etching.
- Such a state can be realized by forming the rough film layer 19 by vacuum deposition as described above.
- the pore diameter of the rough film layer 19 can be obtained by the formula (1) using a mercury intrusion method.
- D ⁇ 4 ⁇ cos ⁇ / P (1)
- P is the pressure applied to fill mercury into the pores
- D is the pore diameter (diameter)
- ⁇ is the surface tension of mercury (480 dyne ⁇ cm ⁇ 1 )
- ⁇ is the contact angle between mercury and the pore wall surface.
- the mode value of the hole diameter is a peak value of the distribution of the hole diameter D.
- the porosity of the rough film layer 19 is about 50% to 80%.
- the porosity can be obtained by converting the weight of the rough film layer 19 and the density of the vapor deposition material.
- the rough film layer 19 is in a state where a plurality of metal fine particles 20 are bonded. Therefore, in the cross section in the vertical direction (stacking direction), there are many connection portions 21 between the metal fine particles 20, and it may be difficult to measure individual particle diameters. In that case, it becomes easy to measure the average particle diameter of the metal fine particles 20 by subjecting the SEM photograph of the horizontal cross section of the metal fine particles 20 to image processing.
- the first dielectric film 8A can be formed on the surface of the metal fine particles 20 simultaneously with the formation of the coarse film layer 19 by performing vapor deposition by flowing oxygen gas and argon gas in the step (2).
- vapor deposition may be performed without flowing oxygen gas and argon gas in the step (2).
- the first dielectric film 8A may be formed by, for example, natural oxidation.
- the first dielectric film 8A can also be formed, for example, by anodic oxidation before the second dielectric film 8B is formed.
- the first dielectric film 8A is formed by oxidation of the metal fine particles 20
- the first dielectric film 8A is formed so as to erode the inside of the metal fine particles 20, and is also formed on the outer surface of the metal fine particles 20.
- the second dielectric film 8B is not formed by oxidation, it is formed only on the outer surface of the first dielectric film 8A.
- the plurality of fine metal particles 20 are continuous from the base material 18 toward the surface layer, whereby the rough film layer 19 composed of a plurality of branched structures is formed. Further, since the rough film layer 19 is formed of a structure branched into a plurality of branches, when used in a capacitor, the impregnation property of an electrolyte or a polymer that is a solid electrolyte is excellent.
- the film thickness of the rough film layer 19 is 20 ⁇ m or more and 80 ⁇ m or less on one side, and is formed on both sides of the substrate 18.
- the rough film layer 19 may be formed only on one side.
- the thickness of the rough film layer 19 is set to 20 ⁇ m or more, the capacitor 7 having a large capacity can be realized.
- 80 micrometers or less the thickness of the rough-film layer 19 can be accurately controlled by the above-mentioned vapor deposition process.
- vapor deposition is taken as an example of the process for forming the rough film layer 19.
- a sparse structure in which a plurality of metal fine particles 20 are connected and a gap is formed between the metal fine particles 20 is used.
- methods other than vapor deposition such as aerosol and sputtering, may be used.
- the second dielectric film 8B is formed of titanium dioxide
- a solution in which 0.05 M (NH 4 ) 2 TiF 6 and 0.1 M ammonium nitrate (NH 4 NO 3 ) are mixed is prepared.
- additives such as a pH adjuster and a reducing agent may be added as appropriate to the solution.
- the liquid temperature of the solution thus prepared is kept at 15 ° C. or lower, for example, 5 ° C., and the foil 9B is immersed in the solution.
- an electrochemical measurement device is used to keep the potential of the foil 9B constant.
- Ag / AgCl is used for the reference electrode, and carbon or platinum is used for the counter electrode.
- the film thickness of the second dielectric film 8B is appropriately adjusted according to the potential and electrolysis time. If the thickness of the second dielectric film 8B is reduced, the capacity of the electrode foil 9A can be increased. For example, setting the potential of the foil 9B between -1.0 V ⁇ -1.5V, by performing the electrolysis of 0.001C / cm 2 ⁇ 5C / cm 2 as the electric quantity, form a good dielectric film 8 in film quality can do.
- the concentration of various reagents to be mixed is appropriately selected because it affects the reaction rate and film thickness.
- a metal compound made of a fluoro complex is used as a supply source of titanium that is a material of the second dielectric film 8B.
- the material is limited to this material as long as metal ions (titanium ions) can exist stably. None happen.
- ammonium nitrate is dissolved, but this is for controlling the pH of the interface, and other nitric acid compounds may be used.
- the same effect can be acquired even if it adjusts the amount of dissolved oxygen in a solution suitably, without using a nitric acid compound.
- other additives can be substituted.
- an organic solvent can be used as the solvent of the solution.
- the second dielectric film 8B is formed by an electrolytic method in which electrolysis is performed using an external power source.
- a reducing agent such as dimethylamine borane is added to a solution containing a metal compound such as (NH 4 ) 2 TiF 6 and a nitric acid compound such as NH 4 NO 3 , and the second dielectric film 8B is electrolessly added. May be formed. That is, the second dielectric film 8B can be formed by an electroless method in which the foil 9B is immersed after the liquid temperature of the solution containing the reducing agent is kept constant. At this time, the film formation rate can be controlled by appropriately adjusting the concentrations of the nitric acid-based compound and the reducing agent. Further, the thickness of the second dielectric film 8B can be adjusted by adjusting the immersion time. Even in the electroless method, the temperature of the solution is preferably maintained at a low temperature (15 ° C. or lower).
- the second dielectric film 8B is formed by an electrolytic method or an electroless method, and then a heat treatment is performed as necessary, so that the dielectric film 8 with higher quality can be obtained.
- heat treatment is performed at a temperature of 150 ° C. to 600 ° C., a good film tends to be obtained.
- the second dielectric film 8B formed zirconia oxide is prepared (NH 4) 2 ZrF 6, instead of the metal compound (NH 4) 2 TiF 6.
- an elemental compound that can be a material of the second dielectric film 8B, such as zirconium, silicon, tantalum, niobium, lanthanum, germanium.
- a second dielectric film 8B can be formed. If the silicon compound is dissolved, the second dielectric film 8B having a relatively low dielectric constant but high withstand voltage can be formed.
- the second dielectric film 8B having a film thickness of about 5 nm to 100 nm can be formed.
- the first dielectric film 8A grows in the thickness direction, and the thickness of the first dielectric film 8A becomes 10 nm or more.
- the thickness of the first dielectric film 8A formed under the second dielectric film 8B is maintained by keeping the temperature of the solution in which the foil 9B is immersed in the electrolytic method or the electroless method. Can be made larger than 0 nm and smaller than 10 nm. If the temperature is too low, the solution in which the foil 9B is immersed solidifies, and therefore the temperature of this solution is preferably adjusted to ⁇ 5 ° C. or more and 15 ° C. or less.
- FIG. 5A shows the relationship between the temperature of the plating solution and the capacity of the finished electrode foil 9A when the second dielectric film 8B made of TiO 2 is formed on an aluminum plain foil of 1 cm ⁇ 2 cm. On the aluminum plain foil, an oxide film corresponding to the first dielectric film 8A is usually formed by natural oxidation. As is apparent from FIG. 5A, the capacity increases in the range of 15 ° C. or lower.
- FIG. 5B shows the relationship between the temperature of the plating solution and the first dielectric film 8A of the finished electrode foil 9A.
- the content of fluorine existing at the interface between the second dielectric film 8B and the first dielectric film 8A can be reduced to less than 5 atm% by setting the temperature of the solution to 15 ° C. or less.
- the reliability of the foil 9A, such as the corrosion resistance can be improved, and the burden on the environment during disposal and decomposition treatment can be reduced.
- the thickness of the first dielectric film 8A becomes thicker than 10 nm, and the capacity decreases as shown in FIG. 5A.
- the temperature of the solution is set to 20 ° C. to 50 ° C.
- a thick oxide film (first dielectric film 8A) of about 25 nm is formed under the second dielectric film 8B.
- the fluorine content present at the interface between the second dielectric film 8B and the first dielectric film 8A is as high as about 10 to 20 atm%.
- the chemical reaction in the solution can be suppressed by setting the temperature of the solution used in the electrolytic method or the electroless method to 15 ° C. or lower. Therefore, the thickness of the first dielectric film 8A formed under the second dielectric film 8B and the content of fluorine existing between the second dielectric film 8B and the first dielectric film 8A can be reduced.
- the reaction between fluorine and the foil 9B is suppressed, and dissolution of the foil 9B can be suppressed.
- aluminum used for the foil 9B is particularly easily oxidized and highly reactive with fluorine, so that dissolution and formation of the first dielectric film 8A are likely to occur. Therefore, when aluminum is used as the foil 9B, it is effective to lower the temperature of the solution and suppress the reaction.
- the temperature of the solution can be adjusted in the range of ⁇ 5 ° C. or more and 15 ° C. or less as described above.
- the first dielectric film 8A formed may be thicker than when the temperature is 5 ° C., but the formation speed of the second dielectric film 8B increases, leading to an improvement in productivity.
- the formation speed becomes slow, but the thickness of the second dielectric film 8B can be easily adjusted.
- electrode foil 9A when using electrode foil 9A as an anode foil, you may perform a repair chemical conversion process suitably.
- a 7% ammonium adipate aqueous solution at 70 ° C. is used, and the conditions are, for example, a formation voltage of 4.5 V, a holding time of 20 minutes, and a formation current density of 0.05 A / cm 2 .
- an electrode foil 9A (sample E1) in which the thickness of the first dielectric film 8A is 5 nm and the thickness of the second dielectric film 8B is 15 nm
- a conventional electrode foil (sample C1) in which the dielectric film is formed only by anodization.
- Table 1 shows the composition of each dielectric film, the film thickness, the dielectric constant, the diameter of the connection part of the metal fine particles 20, the capacity of the electrode foil, and the LC value (leakage current value) of the electrode foil.
- Table 1 shows values in the case where the rough film layer 19 and the dielectric film are formed on one side of the base material 18.
- the thickness of each rough film layer 19 is about 30 ⁇ m.
- the film thickness of the dielectric film is measured by various analytical instruments such as TEM and SEM.
- the dielectric film of the electrode foil of sample C1 was formed by depositing the coarse film layer 19 by vapor deposition in the same manner as the electrode foil 9A of sample E1, and then using a 7% ammonium adipate aqueous solution at 70 ° C. and a formation voltage of 5 V, holding It is produced by chemical conversion at a current density of 0.05 A / cm 2 for 20 minutes.
- the capacity of the electrode foil was measured using an LCR meter in an 8% ammonium borate aqueous solution at 30 ° C. under a measurement area of 10 cm 2 and a measurement frequency of 120 Hz.
- the LC value is measured with the same solution and measurement area as those for the capacitance measurement, and is indicated by a numerical value obtained by reading a current value that flows when a constant voltage is applied to the electrode foil.
- the capacity of the electrode foil 9A of the sample E1 is increased by 280 ⁇ F and the LC value is decreased by 100 ⁇ A as compared with the electrode foil of the sample C1.
- the dielectric film 8 is composed of a laminate of a first dielectric film 8A made of an oxide of the metal fine particles 20 and a second dielectric film 8B made of a metal compound different from the first dielectric film 8A. Because. That is, the first dielectric film 8A is formed by oxidation of the metal fine particles 20, but the second dielectric film 8B is not formed by oxidation of the metal fine particles, but is formed by stacking different materials on the first dielectric film 8A. ing. Accordingly, the second dielectric film 8B can be freely selected from a material different from the metal material of the metal fine particles 20 in order to improve the dielectric constant of the dielectric film 8, increase the withstand voltage, or increase the efficiency of the film formation process. Therefore, the capacity of the capacitor 7 can be easily increased.
- the dielectric constant of aluminum oxide is 10
- the capacitance of the electrode foil is 2000 ⁇ F.
- the formation time of the first dielectric film 8A is short, and the erosion of the first dielectric film 8A to the inside of the metal fine particles 20 is prevented. Can be reduced.
- the second dielectric film 8B has a high dielectric constant, a high capacitance can be maintained even if it is formed thick. In this way, the outer periphery of the metal fine particles 20 can be reinforced by the second dielectric film 8B, and defects can be suppressed. As a result, the capacity of the capacitor 7 can be increased and the leakage current can be reduced.
- connection part 21 of the metal fine particle 20 is constricted and has a structure that can be easily broken.
- the second dielectric film 8B is also formed on the outer periphery of the constricted connection part 21. Therefore, the defect
- the diameter of the constricted connection portion 21 is 0.085 ⁇ m, which is larger than the diameter of the sample C1 of 0.060 ⁇ m. Therefore, in the configuration of the present embodiment, the loss of the rough film layer 19 can be suppressed.
- the rough film layer 19 is a rough structure in which a large number of holes having a thickness of 20 ⁇ m or more and a diameter of 0.20 ⁇ m or less are formed, a large capacity can be realized. It becomes easier to break. Since the first dielectric film 8A is also formed inside the metal fine particles 20, the mechanical strength is weakened when the first dielectric film 8A is formed thick. On the other hand, the first dielectric film 8A is formed thinly as in the present embodiment, and the second dielectric film 8B covering the outer surface of the first dielectric film 8A is formed to increase the mechanical strength and increase the capacity. And reduction of leakage current can be realized.
- the dielectric film 8 may be formed in a dry atmosphere such as physical vapor deposition, sputtering, or chemical vapor deposition.
- a dry atmosphere such as physical vapor deposition, sputtering, or chemical vapor deposition.
- the second dielectric film 8B is formed by a wet method. Therefore, it can be formed substantially continuously on the outer surface of the connecting portion 21 where the metal fine particles 20 are connected and constricted, and the leakage current can be reduced.
- the electrolytic plating method among the plating methods can form the second dielectric film 8B on the conductive metal fine particles 20 regardless of the three-dimensional structure of the rough film layer 19. Therefore, the second dielectric film 8B having a more continuous and uniform film thickness can be formed. It is also possible to form the second dielectric film 8B by forming a metal different from the main component of the metal fine particles 20 by plating and then anodizing the deposited metal, for example.
- the second dielectric film 8B is formed by the LPD method, fluorine remains as an impurity in the second dielectric film 8B.
- the sol-gel method is used, carbon remains, and when the plating method is used, elements such as nitrogen and carbon remain.
- the proportion of hydroxide mixed in the second dielectric film 8B is larger than that in the case of forming by the dry method. Note that the wet method used in this embodiment mode has simpler equipment than the dry method, and can reduce production costs.
- the coarse film layer 19 is a structure in which a plurality of metal fine particles 20 are connected and branched, but for example, a structure in which the metal fine particles 20 are grown and stacked in a column shape may be used. Alternatively, the rough film layer 19 may be formed of a dense structure laminated in a lump shape. Also in these configurations, the continuous and uniform second dielectric film 8B can be efficiently formed by using the wet method.
- the leakage current can be suppressed even when the second dielectric film 8B is peeled off.
- the adhesion between the dielectric film 8 and the metal fine particles 20 is compared to the case where the second dielectric film 8B is directly laminated on the surface of the metal fine particles 20. This contributes to the reduction of leakage current.
- first dielectric film 8A and the second dielectric film 8B are oxides, they have a relatively high affinity. Therefore, compared with the case where the 2nd dielectric film 8B is laminated
- a multilayer solid electrolytic capacitor has been described as an example.
- the present invention may be applied to a wound solid electrolytic capacitor or an electrolytic capacitor using an electrolytic solution.
- the electrode foil 9A is used as the anode foil, a large-capacity capacitor can be produced. Further, the mechanical strength of the rough film layer 19 can be increased and the leakage current can be reduced.
- the rough film layer 19 is formed by vapor deposition, but the rough film layer 19 may be formed by etching the surface of a flat substrate.
- FIG. 6 is a partially cutaway perspective view of the capacitor according to Embodiment 2 of the present invention.
- the capacitor 22 of the present embodiment is an electrolytic capacitor using a liquid electrolyte as a cathode material.
- the capacitor 22 includes a capacitor element 26, an electrolytic solution impregnated in the capacitor element 26, a case 27, an anode terminal 28, a cathode terminal 29, and a sealing material 30.
- the capacitor element 26 is formed by winding an anode foil 23 and a cathode foil 24 with a separator 25 facing each other.
- the case 27 contains the capacitor element 26 and the electrolytic solution.
- the anode terminal 28 is electrically connected to the anode foil 23, and the anode foil 23 is electrically drawn out of the case 27.
- the cathode terminal 29 is electrically connected to the cathode foil 24, and the cathode foil 24 is electrically drawn out of the case 27.
- the anode terminal 28 and the cathode terminal 29 are inserted into the sealing material 30.
- the sealing material 30 seals the opening of the case 27.
- the cathode foil 24 is configured in the same manner as the electrode foil 9A of Embodiment 1 described with reference to FIGS. 3A and 3B. That is, the cathode foil 24 includes the base material 18, the rough film layer 19, the first dielectric film 8A, and the second dielectric film 8B.
- the base material 18 and the rough film layer 19 are made of aluminum.
- the rough film layer 19 is formed on the base material 18.
- the first dielectric film 8A made of aluminum oxide is formed on the surface of the rough film layer 19 by chemical conversion.
- the second dielectric film 8B made of titanium dioxide is laminated on the first dielectric film 8A by a wet method.
- the second dielectric film 8B is disposed on the side facing the separator 25.
- the material of the cathode foil 24 is not limited to this, and can be selected from various conductive materials as in the first embodiment.
- the thickness of the first dielectric film 8A can be formed to be greater than 0 nm and less than 10 nm by setting the temperature of the plating solution to 15 ° C. or less as in the first embodiment. .
- the cathode foil 24 of the present embodiment is manufactured in substantially the same manner as the electrode foil 9A of the first embodiment, description thereof is omitted.
- the rough film layer 19 is a rough structure formed by vapor deposition, like the first embodiment, in which a plurality of metal fine particles 20 are branched irregularly from the surface of the base material.
- the capacity can be increased.
- the capacitance of the electrode foil 9A is 5500 ⁇ F, and the capacitance is increased by 500 ⁇ F compared to the sample C2.
- the capacity component of the cathode foil 24 and the capacity component of the anode foil 23 are connected in series. Therefore, it is desirable that a dielectric film is not formed on the cathode foil 24 and that no capacitive component is generated on the cathode side, and it is preferable that the capacitance of the anode foil 23 is increased to constitute the capacitor 7.
- an oxide film is also formed on the cathode foil 24 by natural oxidation or heat treatment. In order to control these, an oxide film may be formed on the surface of the cathode foil 24 in advance.
- the cathode foil 24 is made of aluminum, chemical conversion is performed at about 2V.
- the dielectric film 8 having a high dielectric constant on the cathode foil 24 in advance is effective for increasing the capacity of the capacitor 7 and is made of a material such as titanium dioxide (second dielectric). If the film 8B) is formed, the deterioration of the cathode surface can be suppressed.
- the electrode foil 9A having the coarse film layer 19 having a large surface area is used for the cathode foil 24.
- the electrode foil 9A may be used for the anode foil 23, and both the cathode foil 24 and the anode foil 23 are used. You may use for. In any case, it contributes to the increase in capacity of the electrode foil 9A, the improvement of the mechanical strength of the rough film layer 19, and the reduction of the leakage current.
- the electrode foil 9A when the electrode foil 9A is used for the capacitor 22, a positive voltage is applied to the anode foil 23 side. Therefore, when the electrode foil 9A is used as the anode foil 23, the laminated second dielectric film 8B may be peeled off by applying a voltage. In the case of performing repair conversion, the possibility of peeling becomes higher. Further, when a positive voltage is applied, metal fine particles under the first dielectric film 8A are formed, and the capacitance may be reduced. Therefore, as in the present embodiment, the electrode foil 9A provided with the second dielectric film 8B is more preferably used as the cathode foil 24 from the viewpoint of product stability.
- the outer surface of the rough film layer 19 is covered with the thick second dielectric film 8B, whereby the mechanical strength of the rough film layer 19 can be increased, Can be suppressed. Therefore, the electrode foil 9A having a large surface area can be stably manufactured.
- the electrolytic solution impregnated in the capacitor element 26 is used.
- a solid electrolyte such as a conductive polymer or an organic semiconductor material may be used instead of the electrolytic solution. These materials may be impregnated after winding the electrode foil and the separator 25 to form the capacitor element 26, or may be impregnated before winding.
- the capacitor electrode is described as an example.
- the second dielectric film 8B is made of titanium dioxide, conductive glass or aluminum is used as the base material 18, and a dye or electrolyte such as a ruthenium complex is used, an electrode such as a dye-sensitized solar cell can be used. Can be used.
- the first dielectric film 8A may be composed of an oxide of this metal layer.
- the second dielectric film 8B is made of titanium dioxide, and can be used for antibacterial, deodorant and water purification products utilizing the decomposition function of organic substances and harmful substances by the photocatalytic action of titanium dioxide.
- the surface area of the rough film layer 19 is increased, so that the antibacterial, deodorant, and water purification functions can be enhanced, and the mechanical strength of the rough film layer 19 is high, realizing a highly reliable application.
- it can.
- it can be used as various electrodes such as a gas sensor.
- the electrode foil according to the present invention can realize a thin film of a high withstand voltage electrolytic capacitor having a small size and a large capacity and a small leakage current.
- the electrode foil according to the present invention has a high mechanical strength and can be applied to applications that require high reliability.
- Capacitor element Capacitor element 7 Capacitor 8 Dielectric film 8A First dielectric film 8B Second dielectric film 9A Electrode foil 9B Foil 10 Anode portion 11 Resist portion 12 Cathode portion 13 Solid electrolyte layer 14 Cathode layer 15 Anode terminal 16 Cathode terminal 16 A Bending portion 17 Exterior Body 18 Base material 19 Coarse film layer 20 Metal fine particle 21 Connection portion 22 Capacitor 23 Anode foil 24 Cathode foil 25 Separator 26 Capacitor element 27 Case 28 Anode terminal 29 Cathode terminal 30 Sealing material
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Abstract
Description
以下、本発明の実施の形態1における電極箔と、この電極箔を用いたコンデンサについて説明する。本実施の形態のコンデンサは、電解質として導電性高分子材料を用いた固体電解コンデンサである。
Pは水銀を空孔内に充填するために加える圧力、Dは空孔径(直径)、γは水銀の表面張力(480dyne・cm-1)、θは水銀と細孔壁面の接触角である。空孔径の最頻値は、この空孔径Dの分布のピーク値である。
図6は本発明の実施の形態2におけるコンデンサの一部切り欠き斜視図である。本実施の形態のコンデンサ22は、陰極材料として液体の電解液を用いた電解コンデンサである。コンデンサ22は、コンデンサ素子26と、コンデンサ素子26に含浸させた電解液と、ケース27と、陽極端子28と、陰極端子29と、封止材30とを有する。
7 コンデンサ
8 誘電膜
8A 第1誘電膜
8B 第2誘電膜
9A 電極箔
9B 箔
10 陽極部
11 レジスト部
12 陰極部
13 固体電解質層
14 陰極層
15 陽極端子
16 陰極端子
16A 折り曲げ部
17 外装体
18 基材
19 粗膜層
20 金属微粒子
21 接続部分
22 コンデンサ
23 陽極箔
24 陰極箔
25 セパレータ
26 コンデンサ素子
27 ケース
28 陽極端子
29 陰極端子
30 封止材
Claims (10)
- 表面に金属層を有する箔と、
前記金属層を構成する金属の酸化物で構成され、前記金属層の上に形成され、厚みが0nmよりも大きく10nm未満である第1誘電膜と、
前記第1誘電膜とは異なる金属化合物を主成分とし、前記第1誘電膜上に形成された第2誘電膜と、を備えた、
電極箔。 - 前記箔は、金属製の基材と、前記基材上に形成された粗膜層と、を有し、
前記粗膜層は、前記基材の表面から金属微粒子が不規則に複数個連なって構成されるとともに、内部に多数の空孔を有する、
請求項1記載の電極箔。 - 前記第1、第2誘電膜は、前記金属微粒子の外周に形成されるとともに、
前記複数の金属微粒子の接続部分は括れていて、前記接続部分の外周にも前記第1、第2誘電膜が形成されている、
請求項2記載の電極箔。 - 前記粗膜層は、複数の枝に枝分かれした構造体である、
請求項2記載の電極箔。 - 前記第1誘電膜は前記金属微粒子の酸化によって前記金属微粒子の内側および外表面に形成され、
前記第2誘電膜は前記第1誘電膜の外表面に形成されて、前記第1誘電膜の機械的強度を補強している、
請求項2記載の電極箔。 - 前記粗膜層の空孔径の最頻値は、0.01μm以上、0.20μm以下である、
請求項2記載の電極箔。 - 前記第2誘電膜は、前記第1誘電膜を構成する酸化物の誘電率よりも高い誘電率を有する材料で構成されている、
請求項1記載の電極箔。 - 前記第1誘電膜と前記第2誘電膜との界面におけるフッ素の含有率が5atm%未満である、
請求項1記載の電極箔。 - 箔の表面に形成された金属層上に、前記金属層の酸化物で構成された第1誘電膜を形成するステップと、
前記第1誘電膜が形成された前記箔を15℃以下の溶液に浸漬して、電解法または無電解法のいずれかにより、前記第1誘電膜とは異なる金属化合物を主成分とする第2誘電膜を形成するとともに、前記第1誘電膜の厚みを10nm未満に抑えるステップと、を備えた、
電極箔の製造方法。 - 陽極部と陰極部とを有するコンデンサ素子と、
前記陽極部と前記陰極部との間に介在する電解質と、
前記コンデンサ素子と前記電解質とを収容する外装体と、を備え、
前記陽極部または前記陰極部の少なくとも一方は、
表面に金属層を有する箔と、
前記金属層を構成する金属の酸化物で構成され、前記金属層上に形成され、厚みが0nmよりも大きく10nm未満である第1誘電膜と、
前記第1誘電膜とは異なる金属化合物を主成分とし、前記第1誘電膜上に形成された第2誘電膜と、を有する電極箔を含む、
コンデンサ。
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US13/497,027 US8654509B2 (en) | 2010-02-15 | 2011-02-07 | Electrode foil, process for producing same, and capacitor using electrode foil |
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DE112011105957T5 (de) * | 2011-12-14 | 2014-08-21 | Intel Corporation | Überwinden von Abweichung bei gestapelten Kondensatoren |
JP5699995B2 (ja) * | 2012-07-02 | 2015-04-15 | 株式会社デンソー | 電力変換装置 |
US10319535B2 (en) * | 2013-09-27 | 2019-06-11 | Intel Corporation | High voltage high power energy storage devices, systems, and associated methods |
KR20210022790A (ko) * | 2019-08-20 | 2021-03-04 | 삼성디스플레이 주식회사 | 표시 장치 및 이의 제조 방법 |
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WO2006117985A1 (ja) * | 2005-04-27 | 2006-11-09 | Nippon Steel Corporation | コンデンサ用電極箔 |
JP2007305776A (ja) * | 2006-05-11 | 2007-11-22 | Nippon Steel Materials Co Ltd | コンデンサ用電極箔及びコンデンサ |
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