JP2021044549A - Solid electrolytic capacitor and method of manufacturing solid electrolytic capacitor - Google Patents

Abstract

To provide a solid electrolytic capacitor having a high withstand voltage and high adhesion between a solid electrolyte layer and a valve action metal substrate.SOLUTION: A solid electrolytic capacitor 1 includes a valve action metal substrate 41 having a dielectric layer 50 on at least one main surface, a mask layer 51 made of an insulating material and provided so as to cover a peripheral edge of the main surface of the valve action metal substrate 41, and a cathode layer 60 provided in that region on the dielectric layer 50 which is surrounded by the mask layer 51. The cathode layer 60 includes a solid electrolyte layer 61 provided on the dielectric layer 50. The solid electrolyte layer 61 includes a first layer 61a filling pores of the dielectric layer 50, a second layer 61b made of the same material as or a different material from that of the first layer 61a and provided at an outer periphery of that region on the dielectric layer 50 which is surrounded by the mask layer 51, and a third layer 61c covering the second layer 61b and the dielectric layer 50.SELECTED DRAWING: Figure 5

Description

The present invention relates to a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor.

The solid electrolytic capacitor includes a valve acting metal substrate having a dielectric layer on the surface of a substrate made of a valve acting metal such as aluminum, and a cathode layer including a solid electrolyte layer provided on the dielectric layer.

For example, Patent Document 1 describes (A) a step of preparing a valve acting metal substrate having a dielectric layer formed on its surface and a first sheet having a solid electrolyte layer provided on the dielectric layer. B) A step of preparing a second sheet made of a metal foil, (C) a step of coating the first sheet with an insulating material, and (D) a conductor layer on the solid electrolyte layer of the first sheet. (E) A step of laminating the first sheet and the second sheet to prepare a laminated sheet, and (F) filling a through hole of the laminated sheet with a sealing material to form a laminated block. It includes a step of manufacturing a body, (G) a step of manufacturing a plurality of element laminated bodies by cutting a laminated block body, and (H) a step of forming a first external electrode and a second external electrode. A method for manufacturing a solid electrolytic capacitor is disclosed.

JP-A-2019-79866

In Patent Document 1, a mask material made of an insulating material such as an insulating resin is applied to the surface of a valve acting metal substrate and solidified or cured to provide a mask layer that covers the end and side portions of each element region. It is described to form. Further, Patent Document 1 describes that a solid electrolyte layer is formed in a region surrounded by a mask layer on the dielectric layer.

However, since the electric field tends to concentrate on the outer peripheral portion of the region surrounded by the mask layer, there is a problem that the withstand voltage of the portion is not sufficient. Further, when the solid electrolyte layer is formed in the region surrounded by the mask layer, there is a problem that the adhesion between the solid electrolyte layer and the valve acting metal substrate is not sufficient.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid electrolytic capacitor having a high withstand voltage and a high adhesion between a solid electrolyte layer and a valve acting metal substrate. It is also an object of the present invention to provide a method for manufacturing the solid electrolytic capacitor.

In the first aspect, the solid electrolytic capacitor of the present invention comprises a valve acting metal substrate having a dielectric layer on at least one main surface and an insulating material so as to cover the periphery of the main surface of the valve acting metal substrate. The cathode layer includes a mask layer provided on the dielectric layer and a cathode layer provided on the dielectric layer in a region surrounded by the mask layer, and the cathode layer is a solid electrolyte provided on the dielectric layer. The solid electrolyte layer including the layer is composed of a first layer that fills the pores of the dielectric layer and the same or different material as the first layer, and is surrounded by the mask layer on the dielectric layer. A second layer provided on the outer peripheral portion of the region and a third layer covering the second layer and the dielectric layer are included.

In the second aspect, the solid electrolytic capacitor of the present invention comprises a valve acting metal substrate having a dielectric layer on at least one main surface and an insulating material so as to cover the periphery of the main surface of the valve acting metal substrate. The cathode layer includes a mask layer provided on the dielectric layer and a cathode layer provided on the dielectric layer in a region surrounded by the mask layer, and the cathode layer is a solid electrolyte provided on the dielectric layer. The solid electrolyte layer including the layer is also provided on the mask layer over the outside of the region surrounded by the mask layer.

In the first aspect, the method for producing a solid electrolytic capacitor of the present invention includes a step of preparing a valve acting metal substrate having a dielectric layer on at least one main surface and a peripheral edge of the main surface of the valve acting metal substrate. The cathode layer comprises a step of forming a mask layer covering the peripheral edge by applying an insulating material, and a step of forming a cathode layer in a region surrounded by the mask layer on the dielectric layer. The step of forming the solid electrolyte layer includes a step of forming a solid electrolyte layer on the dielectric layer, and the solid electrolyte layer is the same as or the same as the first layer for filling the pores of the dielectric layer. A second layer made of different materials and provided on the outer peripheral portion of the region surrounded by the mask layer on the dielectric layer, and a third layer covering the second layer and the dielectric layer are provided. Including.

In the second aspect, the method for producing a solid electrolytic capacitor of the present invention includes a step of preparing a valve acting metal substrate having a dielectric layer on at least one main surface and a peripheral edge of the main surface of the valve acting metal substrate. The cathode layer comprises a step of forming a mask layer covering the peripheral edge by applying an insulating material, and a step of forming a cathode layer in a region surrounded by the mask layer on the dielectric layer. The step of forming the solid electrolyte layer includes a step of forming a solid electrolyte layer on the dielectric layer, and the solid electrolyte layer is also formed on the mask layer over the outside of the region surrounded by the mask layer.

According to the present invention, it is possible to provide a solid electrolytic capacitor having a high withstand voltage and a high adhesion between the solid electrolyte layer and the valve acting metal substrate.

FIG. 1 is a perspective view schematically showing an example of a solid electrolytic capacitor of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of the solid electrolytic capacitor shown in FIG. FIG. 3 is an enlarged cross-sectional view of part III of the solid electrolytic capacitor shown in FIG. FIG. 4 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing another example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention. FIG. 7 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing an example of a main part of the solid electrolytic capacitor according to the second embodiment of the present invention. FIG. 9 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor of the comparative example. FIG. 10 is a cross-sectional view schematically showing an example of a main part of a solid electrolytic capacitor of a comparative example.

Hereinafter, the solid electrolytic capacitor of the present invention and the method for manufacturing the solid electrolytic capacitor will be described.
However, the present invention is not limited to the following configurations, and can be appropriately modified and applied without changing the gist of the present invention. It should be noted that a combination of two or more of the individual desirable configurations described below is also the present invention.

It goes without saying that each of the embodiments shown below is an example, and partial replacement or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, the description of the matters common to the first embodiment will be omitted, and only the differences will be described. In particular, the same action and effect due to the same configuration will not be mentioned sequentially for each embodiment.

[Solid electrolytic capacitor]
FIG. 1 is a perspective view schematically showing an example of a solid electrolytic capacitor of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II of the solid electrolytic capacitor shown in FIG. FIG. 3 is an enlarged cross-sectional view of part III of the solid electrolytic capacitor shown in FIG.

In FIGS. 1 and 2, the length direction of the solid electrolytic capacitor 1 and the insulating resin body 10 is indicated by L, the width direction is indicated by W, and the height direction is indicated by T. Here, the length direction L, the width direction W, and the height direction T are orthogonal to each other.

As shown in FIGS. 1 and 2, the solid electrolytic capacitor 1 has a substantially rectangular parallelepiped outer shape. The solid electrolytic capacitor 1 includes an insulating resin body 10, a first external electrode 20, a second external electrode 30, and a plurality of capacitor elements 70.

A plurality of capacitor elements 70 are embedded in the insulating resin body 10. The insulating resin body 10 has a substantially rectangular parallelepiped outer shape. The insulating resin body 10 is relative to the first main surface 10a and the second main surface 10b facing each other in the height direction T, the first side surface 10c and the second side surface 10d facing each other in the width direction W, and the length direction L. It has a first end surface 10e and a second end surface 10f. One capacitor element 70 may be provided inside the insulating resin body 10.

As described above, the insulating resin body 10 has a substantially rectangular parallelepiped outer shape, but it is preferable that the corners and the ridges are rounded. The corner portion is a portion where the three surfaces of the insulating resin body 10 intersect, and the ridge portion is a portion where the two surfaces of the insulating resin body 10 intersect.

The insulating resin body 10 is composed of, for example, a substrate 11 and a mold portion 12 provided on the substrate 11. The insulating resin body 10 may be composed of only the mold portion 12.

The substrate 11 is an insulating resin substrate such as a glass epoxy substrate. The bottom surface of the substrate 11 constitutes the second main surface 10b of the insulating resin body 10. The thickness of the substrate 11 is, for example, 100 μm.

The mold portion 12 is made of an insulating resin such as an epoxy resin. It is preferable that the insulating resin is dispersed and mixed with an oxide of glass or Si as a filler. The mold portion 12 is provided on the substrate 11 so as to cover the plurality of capacitor elements 70.

Each of the plurality of capacitor elements 70 includes an anode portion 40, a dielectric layer 50, and a cathode layer 60. The plurality of capacitor elements 70 are stacked on the substrate 11 in the height direction T. The extending direction of each of the plurality of capacitor elements 70 is substantially parallel to the main surface of the substrate 11.

The anode portion 40 is made of a valve acting metal substrate 41. As shown in FIG. 3, the valve acting metal substrate 41 has an outer surface provided with a plurality of recesses. The outer surface of the valve acting metal substrate 41 is porous. Since the outer surface of the valve-acting metal substrate 41 is porous, the surface area of the valve-acting metal substrate 41 is increased. The case is not limited to the case where both the front surface and the back surface of the valve acting metal substrate 41 are porous, and only one of the front surface and the back surface of the valve acting metal substrate 41 may be porous.

The valve acting metal substrate 41 is composed of, for example, a simple substance of a metal such as aluminum, tantalum, niobium, titanium, zirconium, or a valve acting metal such as an alloy containing these metals. An oxide film can be formed on the surface of the valve acting metal.

The anode portion 40 may be composed of a core portion and a porous portion provided around the core portion, and the surface of the metal foil is etched, and the surface of the metal foil is made of porous fine powder. Those having formed a body or the like can be appropriately adopted.

The dielectric layer 50 is provided on the outer surface of the valve acting metal substrate 41. The dielectric layer 50 is preferably formed of an oxide film provided on the surface of the valve acting metal. Specifically, the dielectric layer 50 is made of an oxide of aluminum. As will be described later, the aluminum oxide is formed by anodizing the outer surface of the valve acting metal substrate 41.

The cathode layer 60 is provided on the outer surface of the dielectric layer 50. In FIG. 2, the cathode layer 60 includes a solid electrolyte layer 61, a conductor layer 62, and a cathode extraction layer 63.

The solid electrolyte layer 61 is provided on a part of the outer surface of the dielectric layer 50. The solid electrolyte layer 61 is not provided on the outer surface of the dielectric layer 50 provided on the outer surface of the valve acting metal substrate 41 located closer to the second end surface 10f. In the dielectric layer 50 of this portion, the portion adjacent to the portion where the solid electrolyte layer 61 is provided is covered with the mask layer 51, which will be described later, on the outer surface.

As shown in FIG. 3, the solid electrolyte layer 61 is preferably provided so as to fill a plurality of pores (recesses) of the valve acting metal substrate 41. However, it is sufficient that the solid electrolyte layer 61 covers the above-mentioned part of the outer surface of the dielectric layer 50, and there are pores (recesses) of the valve acting metal substrate 41 that are not filled by the solid electrolyte layer 61. You may.

As the material constituting the solid electrolyte layer 61, for example, conductive polymers such as polypyrroles, polythiophenes, and polyanilines are used. Among these, polythiophenes are preferable, and poly (3,4-ethylenedioxythiophene) called PEDOT is particularly preferable. Further, the conductive polymer may contain a dopant such as polystyrene sulfonic acid (PSS).

In the solid electrolyte layer 61, for example, a treatment liquid containing a polymerizable monomer such as 3,4-ethylenedioxythiophene is used to polymerize poly (3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer 50. It is formed by a method of forming a film, a method of applying a dispersion liquid of a conductive polymer such as poly (3,4-ethylenedioxythiophene) to the surface of the dielectric layer 50 and drying it. It is preferable to form the solid electrolyte layer for the inner layer that fills the pores (recesses) of the valve acting metal substrate 41, and then form the solid electrolyte layer for the outer layer that covers the entire dielectric layer 50.

The conductor layer 62 is provided on the outer surface of the solid electrolyte layer 61. The conductor layer 62 includes, for example, a carbon layer or a silver layer. Further, the conductor layer 62 may be a composite layer in which a silver layer is provided on the outer surface of the carbon layer, or a mixed layer containing carbon and silver.

The cathode extraction layer 63 is provided on the outer surface of the conductor layer 62. The conductor layers 62 of the capacitor elements 70 adjacent to each other in the stacking direction are electrically connected to each other by the cathode extraction layer 63. The width of the cathode lead-out layer 63 in the width direction W is, for example, equivalent to the width of the valve acting metal substrate 41 in the width direction W.

The cathode lead-out layer 63 can be formed of a metal foil or a printed electrode layer.

In the case of a metal foil, it is preferably composed of at least one metal selected from the group consisting of Al, Cu, Ag and alloys containing these metals as main components. Further, as the metal foil, a metal foil having a surface coated with carbon or titanium by a film forming method such as sputtering or vapor deposition may be used. Above all, it is preferable to use carbon-coated aluminum foil.

In the case of a printed electrode layer, the cathode extraction layer can be formed in a predetermined region by forming the electrode paste on the conductor layer by sponge transfer, screen printing, spray coating, dispenser, inkjet printing, or the like. As the electrode paste, an electrode paste containing Ag, Cu or Ni as a main component is preferable. When the cathode extraction layer is used as the printed electrode layer, the cathode extraction layer can be made thinner than when a metal foil is used.

As described above, in the dielectric layer 50 of the portion where the solid electrolyte layer 61 is not provided, the portion adjacent to the portion where the solid electrolyte layer 61 is provided has a composition different from that of the insulating resin body 10. The outer surface is covered with the mask layer 51. The mask layer 51 covers the outer surface of the valve acting metal substrate 41 from a position adjacent to the portion where the solid electrolyte layer 61 is provided to the end portion of the anode portion 40 closer to the second end surface 10f.

The mask layer 51 is formed by applying, for example, a mask material such as a composition containing an insulating resin.
Examples of the insulating resin include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, etc.), and soluble polyimide. Examples thereof include a composition composed of a siloxane and an epoxy resin, a polyimide resin, a polyamideimide resin, and a derivative or precursor thereof.

The first external electrode 20 is provided on the first end surface 10e of the insulating resin body 10. In FIG. 1, the first external electrode 20 is provided from the first end surface 10e of the insulating resin body 10 to each of the first main surface 10a, the second main surface 10b, the first side surface 10c, and the second side surface 10d. Has been done. The first external electrode 20 is electrically connected to the cathode layer 60 of each of the plurality of capacitor elements 70.

The first external electrode 20 is composed of at least one plating layer provided on the first end surface 10e of the insulating resin body 10. For example, the first external electrode 20 is provided on the Cu plating layer provided on the first end surface 10e of the insulating resin body 10, the Ni plating layer provided on the Cu plating layer, and the Ni plating layer. It is composed of a Sn plating layer.

The first external electrode 20 is directly or indirectly connected to the cathode lead-out layer 63 on the first end surface 10e of the insulating resin body 10.

The second external electrode 30 is provided on the second end surface 10f of the insulating resin body 10. In FIG. 1, the second external electrode 30 is provided from the second end surface 10f of the insulating resin body 10 to each of the first main surface 10a, the second main surface 10b, the first side surface 10c, and the second side surface 10d. Has been done. The second external electrode 30 is electrically connected to the anode portion 40 of each of the plurality of capacitor elements 70.

The second external electrode 30 is composed of at least one plating layer provided on the second end surface 10f of the insulating resin body 10. For example, the second external electrode 30 is provided on the Cu plating layer provided on the second end surface 10f of the insulating resin body 10, the Ni plating layer provided on the Cu plating layer, and the Ni plating layer. It is composed of a Sn plating layer.

The second external electrode 30 is directly or indirectly connected to each of the valve acting metal substrates 41 of the plurality of capacitor elements 70 on the second end surface 10f of the insulating resin body 10.

(First Embodiment)
FIG. 4 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention.

As shown in FIGS. 4 and 5, the mask layer 51 is provided so as to cover the peripheral edge of the main surface of the valve acting metal substrate 41. A solid electrolyte layer 61 is provided on the dielectric layer 50 in a region surrounded by the mask layer 51.

In FIGS. 4 and 5, the solid electrolyte layer 61 includes a first layer 61a, a second layer 61b, and a third layer 61c.

The first layer 61a is an inner layer of the solid electrolyte layer 61 and fills the pores (see FIG. 3) of the dielectric layer 50.

The second layer 61b is made of the same or different material as the first layer 61a, which is the inner layer of the solid electrolyte layer 61. The second layer 61b is provided on the outer peripheral portion of the region surrounded by the mask layer 51 on the dielectric layer 50.

The third layer 61c is an outer layer of the solid electrolyte layer 61, and covers the second layer 61b and the dielectric layer 50.

In the solid electrolytic capacitor according to the first embodiment of the present invention, a second layer made of the same or different material as the first layer, which is the inner layer of the solid electrolyte layer, is selectively formed on the outer peripheral portion of the region surrounded by the mask layer. It is thickly formed. As a result, the withstand voltage of the outer peripheral portion where the electric field is likely to be concentrated can be increased. Further, the outer peripheral portion of the third layer, which is the outer layer of the solid electrolyte layer having poor adhesion to the valve acting metal substrate, is brought into contact with the second layer having good affinity with the third layer, whereby the solid electrolyte layer and the valve are formed. Adhesion with the working metal substrate can be improved. As a result, the solid electrolyte layer is less likely to be peeled off in a high temperature or high humidity environment, and the reliability of the solid electrolytic capacitor is improved.

In the first embodiment of the present invention, the second layer of the solid electrolyte layer is preferably provided on the entire outer peripheral portion of the region surrounded by the mask layer, but the solid electrolyte layer is partially provided on the outer peripheral portion. There may be a portion where the second layer is not provided.

In the first embodiment of the present invention, the thickness of the second layer is preferably 0.1 μm or more and 2 μm or less. The thickness of the second layer means the maximum thickness of the second layer.

In the first embodiment of the present invention, the thickness of the second layer is preferably 10% or more and 75% or less of the thickness of the third layer. The thickness of the third layer means the maximum thickness of the third layer.

In the first embodiment of the present invention, the solid electrolyte layer may also be provided on the mask layer over the outside of the region surrounded by the mask layer, as in the second embodiment described later. Specifically, a third layer of the solid electrolyte layer may be provided on the mask layer over the outside of the region surrounded by the mask layer.

FIG. 6 is a cross-sectional view schematically showing another example of a main part of the solid electrolytic capacitor according to the first embodiment of the present invention.
As shown in FIG. 6, the third layer 61c may also be provided on the mask layer 51.

In the first embodiment of the present invention, when the solid electrolyte layer is also provided on the mask layer over the outside of the region surrounded by the mask layer, the width of the solid electrolyte layer provided on the mask layer is It is preferably 10 μm or more and 100 μm or less. Specifically, the width of the third layer provided on the mask layer is preferably 10 μm or more and 100 μm or less.

In the first embodiment of the present invention, when the solid electrolyte layer is also provided on the mask layer over the outside of the region surrounded by the mask layer, the width of the solid electrolyte layer provided on the mask layer is , It is preferable that the width of the mask layer is 0.1% or more and 25% or less. Specifically, the width of the third layer provided on the mask layer is preferably 0.1% or more and 25% or less of the width of the mask layer.

(Second Embodiment)
FIG. 7 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing an example of a main part of the solid electrolytic capacitor according to the second embodiment of the present invention.

As shown in FIGS. 7 and 8, the mask layer 51 is provided so as to cover the peripheral edge of the main surface of the valve acting metal substrate 41. A solid electrolyte layer 61 is provided on the dielectric layer 50 in a region surrounded by the mask layer 51.

In FIGS. 7 and 8, the solid electrolyte layer 61 is also provided on the mask layer 51 over the outside of the region surrounded by the mask layer 51. In the examples shown in FIGS. 7 and 8, the solid electrolyte layer 61 includes an inner layer 61a and an outer layer 61c. The outer layer 61c is also provided on the mask layer 51.

In the solid electrolytic capacitor according to the second embodiment of the present invention, the solid electrolyte layer is formed so as to cover the outer peripheral portion of the region surrounded by the mask layer. As a result, the withstand voltage of the outer peripheral portion where the electric field is likely to be concentrated can be increased. Further, by contacting the outer peripheral portion of the solid electrolyte layer having poor adhesion to the valve acting metal substrate with the mask layer having good affinity with the solid electrolyte layer, the adhesion between the solid electrolyte layer and the valve acting metal substrate can be improved. Can be improved. As a result, the solid electrolyte layer is less likely to be peeled off in a high temperature or high humidity environment, and the reliability of the solid electrolytic capacitor is improved.

In the second embodiment of the present invention, the solid electrolyte layer is preferably provided over the entire outside of the region surrounded by the mask layer, but the solid electrolyte layer is provided on a part of the outside of the region. There may be a missing part. Further, the outer layer of the solid electrolyte layer may be divided into two or more layers, and the inner portion and the outer portion of the region surrounded by the mask layer may be formed separately.

In the second embodiment of the present invention, the width of the solid electrolyte layer provided on the mask layer is preferably 10 μm or more and 100 μm or less.

In the second embodiment of the present invention, the width of the solid electrolyte layer provided on the mask layer is preferably 0.1% or more and 25% or less of the width of the mask layer.

In the first and second embodiments of the present invention, the mask layer is preferably provided on the entire peripheral edge of the main surface of the valve acting metal substrate, but is one of the peripheral edges of the main surface of the valve acting metal substrate. There may be a portion where the mask layer is not provided in the portion.

[Manufacturing method of solid electrolytic capacitor]
The method for manufacturing a solid electrolytic capacitor of the present invention includes a step of preparing a valve acting metal substrate having a dielectric layer on at least one main surface, and applying an insulating material to the peripheral edge of the main surface of the valve acting metal substrate. A step of forming a mask layer covering the peripheral edge thereof and a step of forming a cathode layer on the dielectric layer in a region surrounded by the mask layer are provided.

The solid electrolytic capacitor 1 shown in FIG. 1 is manufactured as follows, for example.

When manufacturing the solid electrolytic capacitor 1, first, the capacitor element 70 is prepared in step S10. Specifically, the following steps S11 to S14 are carried out.

In step S11, the dielectric layer 50 is provided on the outer surface of the valve acting metal substrate 41. For example, an aluminum foil as a valve acting metal substrate 41 is immersed in an aqueous solution of ammonium adipate and anodized to form an oxide of aluminum to be a dielectric layer 50. When the chemical foil on which the aluminum oxide is already formed is cut and used as the valve acting metal substrate 41, the valve acting metal substrate 41 after cutting is used to form the aluminum oxide on the cut surface. Is immersed again in an aqueous solution of ammonium adipate and anodized.

In step S12, a part of the valve acting metal substrate 41 is masked. This masking is performed to define the formation region of the solid electrolyte layer 61 performed in the next step. Specifically, a mask material made of an insulating resin such as a polyimide resin or a polyamide-imide resin is applied to the peripheral edge of the outer surface of the valve acting metal substrate 41. The masking portion formed by this step becomes the mask layer 51.

In step S13, the solid electrolyte layer 61 is provided on a part of the outer surface of the dielectric layer 50. For example, a conductive polymer dispersion is adhered to and dried on the outer surface of the dielectric layer 50 located in the formation region of the solid electrolyte layer 61 defined by the masking portion formed in step S12, and the conductive polymer is dried. Form a film. A treatment liquid containing a polymerizable monomer such as 3,4-ethylenedioxythiophene and an oxidizing agent may be attached to form a conductive polymer film by chemical polymerization. This conductive polymer film becomes the solid electrolyte layer 61.

When manufacturing the solid electrolytic capacitor shown in FIGS. 4 and 5, the solid electrolyte layer 61 includes the above-mentioned first layer 61a, second layer 61b, and third layer 61c.

The first layer 61a is formed as an inner layer of the solid electrolyte layer 61.

The second layer 61b is formed at the same time as the first layer 61a by utilizing, for example, the coffee stain phenomenon. The coffee stain phenomenon is a phenomenon in which when a coffee droplet dries, the peripheral portion of the coffee droplet becomes thicker and the other peripheral portion becomes thinner. Also in the treatment liquid and the dispersion liquid for forming the first layer 61a, the peripheral portion of the first layer 61a becomes thicker by drying depending on the composition, and the first layer 61a is formed as the second layer 61b. The third layer 61c is preferably formed by printing a conductive polymer paste by screen printing or the like. The third layer 61c is formed as an outer layer of the solid electrolyte layer 61.

Alternatively, the second layer 61b may be formed by selectively and thickly applying a treatment liquid or a dispersion liquid for forming the first layer 61a to the outer peripheral portion of the region surrounded by the mask layer 51. Further, the second layer 61b may be formed by a treatment liquid or a dispersion liquid made of a material different from that of the first layer 61a.

On the other hand, in the case of manufacturing the solid electrolytic capacitor shown in FIGS. 7 and 8, the solid electrolyte layer 61 is also formed on the mask layer 51 over the outside of the region surrounded by the mask layer 51. At this time, the solid electrolyte layer 61 may be formed over two or more layers. For example, the inside and the outside of the region surrounded by the mask layer 51 may be formed individually, or the region surrounded by the mask layer 51 after being formed only inside the region surrounded by the mask layer 51. It may be further formed so as to extend to the outside.

Next, in step S14, the conductor layer 62 is provided on the outer surface of the solid electrolyte layer 61. For example, a carbon layer is formed by applying carbon to the outer surface of the solid electrolyte layer 61, and then a silver layer is formed by applying silver to the outer surface of the carbon layer. After that, the cathode extraction layer 63 is provided on the outer surface of the conductor layer 62.

The capacitor element 70 is prepared by going through the steps S11 to S14.

Next, in step S20, the capacitor element 70 is provided inside the insulating resin body 10. Specifically, the following steps S21 and S22 are carried out.

In step S21, a plurality of capacitor elements 70 are laminated on the substrate 11. Specifically, a plurality of capacitor elements 70 are laminated on the substrate 11. At this time, it is preferable to connect the conductor layer 62 of the capacitor element 70 and the substrate 11 with a conductive adhesive such as Ag paste. Subsequently, it is preferable that the substrate 11 and the capacitor element 70 are thermocompression bonded.

In step S22, a plurality of capacitor elements 70 are molded using an insulating resin such as an epoxy resin. Specifically, the substrate 11 is mounted on the upper mold by the molding method, and the upper mold and the lower mold are molded in a state where an insulating resin such as epoxy resin is heated and melted in the cavity of the lower mold. The mold portion 12 is formed by tightening and solidifying the insulating resin.

Subsequently, in step S31, it is preferable to cut the substrate 11 and the capacitor element 70 so as to divide the masking portion formed in step S12. Specifically, the molded substrate 11 and the capacitor element 70 are cut by push-cutting, dicing, or laser cutting. By this step, a chip containing the insulating resin body 10 is formed.

In step S32, it is preferable to barrel-polish the tip. Specifically, the chip is enclosed in a small box called a barrel together with an abrasive, and the chip is polished by rotating the barrel. As a result, the corners and ridges of the chip are rounded.

In step S33, the first external electrode 20 and the second external electrode 30 are formed at both ends of the chip. For example, by electrolytic plating, Cu plating layers are formed at both ends of the chip. Subsequently, a Ni plating layer is formed on the Cu plating layer by electrolytic plating. Then, a Sn plating layer is formed on the Ni plating layer by electrolytic plating.

The solid electrolytic capacitor 1 is manufactured through the above steps.

The method for producing the solid electrolytic capacitor of the present invention is not particularly limited, and for example, it may be produced by the method described in JP-A-2019-79866.

Hereinafter, examples in which the solid electrolytic capacitor of the present invention is disclosed more specifically will be shown. The present invention is not limited to these examples.

[Manufacturing of capacitors]
(Comparison example)
FIG. 9 is a plan view schematically showing an example of a main part of the solid electrolytic capacitor of the comparative example. FIG. 10 is a cross-sectional view schematically showing an example of a main part of a solid electrolytic capacitor of a comparative example.

As shown in FIGS. 9 and 10, after forming the mask layer 51 so as to cover the peripheral edge of the valve acting metal substrate 41 having the dielectric layer 50 on the surface, the solid electrolyte layer 61 is formed in the region surrounded by the mask layer 51. Was formed.

As the valve acting metal substrate 41, an aluminum chemical conversion foil having an etching layer on the surface was prepared. The dielectric layer 50 was formed on the cut surface of the aluminum chemical conversion foil by immersing the surface of the aluminum chemical conversion foil in an aqueous solution of ammonium adipate and performing anodizing treatment.

The mask layer 51 was formed by applying a mask material to both surfaces of the valve acting metal substrate 41 by screen printing. Polyimide was used as the mask material.

A conductive polymer dispersion was applied by inkjet to the dielectric layer 50 in the region surrounded by the mask layer 51 to form the inner layer 61a of the solid electrolyte layer 61. Further, the conductive polymer paste was printed by screen printing to form the outer layer 61c of the solid electrolyte layer 61.

A capacitor element was obtained by screen-printing a carbon paste on the surface of the solid electrolyte layer 61 to form a carbon layer, and then screen-printing a silver paste on the carbon layer to form a conductor layer.

The obtained capacitor elements were laminated to obtain a laminated body. Then, the laminate was sealed with an epoxy resin to form an external electrode, whereby a finished capacitor was obtained.

(Example 1-1)
When the inner layer 61a of the solid electrolyte layer 61 is formed by inkjet, a coating pattern is used in which only the outer peripheral portion of the region surrounded by the mask layer 51 is selectively overcoated. A capacitor element having a part was manufactured. A finished product of the capacitor was obtained by the same method as in the comparative example.

(Example 1-2)
By adding an additive that easily causes the coffee stain phenomenon to the conductive polymer dispersion, a capacitor element having the main parts shown in FIGS. 4 and 5 was produced. Ethanol was used as the additive. A finished product of the capacitor was obtained by the same method as in the comparative example.

(Example 2-1)
When the outer layer 61c of the solid electrolyte layer 61 is formed by screen printing, the printing pattern in which the outer layer 61c is formed over the outside of the region surrounded by the mask layer 51 is used, so that the main parts shown in FIGS. 7 and 8 are shown. A capacitor element equipped with the above was manufactured. A finished product of the capacitor was obtained by the same method as in the comparative example.

[Withstand voltage]
The breakdown voltage was measured in order to evaluate the withstand voltage of the capacitors of Comparative Example, Example 1-1, Example 1-2 and Example 2-1. The breaking voltage was measured by measuring the voltage when a constant current of 100 μA was passed through the device for 1 minute, and the maximum value of the reached voltage was taken as the breaking voltage. Table 1 shows the relative values when the breakdown voltage of the comparative example is 1.

[ESR rate of change]
The equivalent series resistance (ESR) at 100 kHz was measured for the capacitors of Comparative Example 1-1, Example 1-2 and Example 2-1 using an LCR meter, and this value was used as the initial ESR. Further, after performing a high temperature load test in which these capacitors were left at 105 ° C. for 1000 hours, the ESR at 100 kHz was measured. Table 1 shows the ESR change rate (initial ratio) before and after the test.

From the results of Examples 1-1 and 1-2, a second layer made of the same material as the first layer, which is the inner layer of the solid electrolyte layer, is selectively thickened on the outer peripheral portion of the region surrounded by the mask layer. It can be seen that by forming the withstand voltage, the withstand voltage can be increased and the ESR change rate can be decreased.

From the results of Example 2-1 that the withstand voltage can be increased and the ESR change rate can be decreased by forming the solid electrolyte layer so as to cover the outer peripheral portion of the region surrounded by the mask layer. I understand.

1 Solid electrolytic capacitor 10 Insulating resin body 10a 1st main surface 10b 2nd main surface 10c 1st side surface 10d 2nd side surface 10e 1st end surface 10f 2nd end surface 11 Substrate 12 Molded part 20 1st external electrode 30 2nd external electrode 40 Anode part 41 Valve acting metal substrate 50 Dielectric layer 51 Mask layer 60 Cathode layer 61 Solid electrolyte layer 61a First layer (inner layer) of solid electrolyte layer
61b Second layer of solid electrolyte layer 61c Third layer (outer layer) of solid electrolyte layer
62 Conductor layer 63 Cathode lead-out layer 70 Capacitor element

Claims (10)

A valve acting metal substrate having a dielectric layer on at least one main surface,
A mask layer made of an insulating material and provided so as to cover the peripheral edge of the main surface of the valve acting metal substrate.
A cathode layer provided in a region surrounded by the mask layer on the dielectric layer is provided.
The cathode layer includes a solid electrolyte layer provided on the dielectric layer.
The solid electrolyte layer is made of a first layer that fills the pores of the dielectric layer and a material that is the same as or different from that of the first layer, and is the outer periphery of a region on the dielectric layer surrounded by the mask layer. A solid electrolytic capacitor including a second layer provided on the portion, a third layer covering the second layer and the dielectric layer. The solid electrolytic capacitor according to claim 1, wherein the thickness of the second layer is 0.1 μm or more and 2 μm or less. The solid electrolytic capacitor according to claim 1 or 2, wherein the thickness of the second layer is 10% or more and 75% or less of the thickness of the third layer. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein the solid electrolyte layer is also provided on the mask layer over the outside of the region surrounded by the mask layer. A valve acting metal substrate having a dielectric layer on at least one main surface,
A mask layer made of an insulating material and provided so as to cover the peripheral edge of the main surface of the valve acting metal substrate.
A cathode layer provided in a region surrounded by the mask layer on the dielectric layer is provided.
The cathode layer includes a solid electrolyte layer provided on the dielectric layer.
The solid electrolyte layer is a solid electrolytic capacitor that is also provided on the mask layer over the outside of the region surrounded by the mask layer. The solid electrolytic capacitor according to claim 4 or 5, wherein the width of the solid electrolyte layer provided on the mask layer is 10 μm or more and 100 μm or less. The solid electrolytic capacitor according to any one of claims 4 to 6, wherein the width of the solid electrolyte layer provided on the mask layer is 0.1% or more and 25% or less of the width of the mask layer. .. A step of preparing a valve acting metal substrate having a dielectric layer on at least one main surface, and
A step of forming a mask layer covering the peripheral edge by applying an insulating material to the peripheral edge of the main surface of the valve acting metal substrate.
A step of forming a cathode layer in a region surrounded by the mask layer on the dielectric layer is provided.
The step of forming the cathode layer includes a step of forming a solid electrolyte layer on the dielectric layer.
The solid electrolyte layer is made of a first layer that fills the pores of the dielectric layer and a material that is the same as or different from that of the first layer, and is the outer periphery of a region on the dielectric layer surrounded by the mask layer. A method for manufacturing a solid electrolytic capacitor, comprising a second layer provided on the portion, a third layer covering the second layer and the dielectric layer. The method for manufacturing a solid electrolytic capacitor according to claim 8, wherein the second layer is formed at the same time as the first layer by utilizing the coffee stain phenomenon. A step of preparing a valve acting metal substrate having a dielectric layer on at least one main surface, and
A step of forming a mask layer covering the peripheral edge by applying an insulating material to the peripheral edge of the main surface of the valve acting metal substrate.
A step of forming a cathode layer in a region surrounded by the mask layer on the dielectric layer is provided.
The step of forming the cathode layer includes a step of forming a solid electrolyte layer on the dielectric layer.
A method for manufacturing a solid electrolytic capacitor, wherein the solid electrolyte layer is also formed on the mask layer over the outside of a region surrounded by the mask layer.

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