Solid electrolytic capacitor and method for producing solid electrolytic capacitor

Abstract

A solid electrolytic capacitor 1 comprises: a valve action metal substrate 11 having a dielectric layer 12 on at least one main surface thereof; a solid electrolyte layer 13 provided on the dielectric layer 12; and a cathode foil 21 provided on the solid electrolyte layer 13. The solid electrolytic capacitor 1 has a substantially rectangular parallelepiped shape having a first main surface 1a and a second main surface 1b facing each other in the lamination direction, a first side surface 1c and a second side surface 1d facing each other in the width direction orthogonal to the lamination direction, and a first end surface 1e and a second end surface 1f facing each other in the length direction orthogonal to the lamination direction and the width direction. In the solid electrolytic capacitor 1, a first external electrode 50 electrically connected to the valve action metal substrate 11 is provided on the first end surface 1c, and a second external electrode 60 electrically connected to the cathode foil 21 is provided on the second end surface 1f, and, on at least one of the first side surface 1c and the second side surface 1d, the distance d1 from a side surface to the valve action metal substrate 11 is different from the distance d2 from the side surface to the cathode foil 21 in the width direction.

Description

Solid electrolytic capacitor and method for manufacturing a solid electrolytic capacitor

[0001] This invention relates to a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor.

[0002] A solid electrolytic capacitor comprises a valve-acting metal substrate having a porous portion on the surface of a substrate made of a valve-acting metal such as aluminum, a dielectric layer formed on the surface of the porous portion, a solid electrolyte layer provided on the dielectric layer, and a conductive layer (also called a current collector layer) provided on the solid electrolyte layer.

[0003] For example, Patent Document 1 discloses a solid electrolytic capacitor in which a dielectric film is formed on the surface of a valve-acting porous metal foil, a capacitor element is laminated on the dielectric film, a solid electrolyte layer is formed on the solid electrolyte layer, a current collector layer is formed on the solid electrolyte layer, and then an outer casing is provided on one end face of the outer periphery with the laminated valve-acting porous metal foil exposed, and a part of the current collector layer or the cathode part of the capacitor element exposed on the other end face, and external electrodes are provided on both ends of this outer casing, wherein a zinc layer is formed on the exposed surface of the valve-acting porous metal foil, and a nickel layer is formed on this zinc layer.

[0004] Such solid electrolytic capacitors are manufactured by, for example, alternately stacking multiple anode sheets made by coating a conductive polymer onto chemically converted electrolytic aluminum foil and cathode sheets made of aluminum foil or the like to create a laminate, then separating the laminate into individual pieces using a dicer or the like, sealing the sides of the individual pieces (the sides on which external electrodes are not formed), and forming external electrodes on the end faces. The individualized laminate is also simply called a base body.

[0005] Patent No. 6724881

[0006] However, it has been found that, depending on the operating conditions, the solid electrolytic capacitor described in Patent Document 1 may experience characteristic degradation due to the ionization of the valve metal of the anode by moisture that has entered from the outside, causing migration from the anode side to the cathode side on the cross-section of the dielectric film formed during the individualization of the laminate.

[0007] In other words, the present invention aims to provide a solid electrolytic capacitor and a method for manufacturing the same that can prevent characteristic degradation due to migration.

[0008] The solid electrolytic capacitor of the present invention comprises a valve-acting metal substrate having a dielectric layer on at least one main surface, a solid electrolyte layer provided on the dielectric layer, and a cathode foil provided on the solid electrolyte layer, and is a substantially rectangular parallelepiped solid electrolytic capacitor having a first main surface and a second main surface facing each other in the stacking direction, a first side surface and a second side surface facing each other in the width direction perpendicular to the stacking direction, and a first end surface and a second end surface facing each other in the length direction perpendicular to the stacking direction and the width direction, wherein the first end surface is provided with a first external electrode electrically connected to the valve-acting metal substrate, and the second end surface is provided with a second external electrode electrically connected to the cathode foil, and the distance d from the side surface in the width direction to the valve-acting metal substrate is at least one of the first side surface and the second side surface. １ The distance d from the above-mentioned side surface to the above-mentioned cathode foil. ２ They are different.

[0009] The present invention provides a method for manufacturing a solid electrolytic capacitor, comprising: a lamination step of laminating a valve-acting metal substrate having a dielectric layer on its surface, a solid electrolyte layer, and a cathode foil to obtain a laminate of the valve-acting metal substrate, the solid electrolyte layer, and the cathode foil; and a fragmentation step of cutting the laminate to form individual pieces, wherein in the lamination step, the valve-acting metal substrate, the solid electrolyte layer, and the cathode foil are laminated such that a non-opposing region is formed where at least one of the valve-acting metal substrate and the cathode foil is not laminated when viewed from the lamination direction; and in the fragmentation step, the laminate is cut such that the cut surface obtained by cutting the non-opposing region becomes the side surface of the fragmented laminate.

[0010] According to the present invention, it is possible to provide a solid electrolytic capacitor that can prevent degradation due to migration, and a method for manufacturing the same.

[0011] Figure 1 is a schematic perspective view showing an example of a solid electrolytic capacitor of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 1. Figure 4 is a schematic diagram showing the positions of the valve-acting metal substrate and cathode foil constituting the solid electrolytic capacitor shown in Figure 1 superimposed on the outer shape of the base body. Figure 5 is a schematic diagram showing the positions of the valve-acting metal substrate constituting the solid electrolytic capacitor shown in Figure 1 superimposed on the outer shape of the base body. Figure 6 is a schematic diagram showing the positions of the cathode foil constituting the solid electrolytic capacitor shown in Figure 1 superimposed on the outer shape of the base body. Figure 7 is a schematic cross-sectional view showing another example of a solid electrolytic capacitor of the present invention. Figure 8 is a schematic cross-sectional view showing yet another example of a solid electrolytic capacitor of the present invention. Figure 9 is a schematic cross-sectional view showing yet another example of a solid electrolytic capacitor of the present invention. Figure 10 is a schematic top view showing an example of a first sheet used in the lamination process. Figure 11 is a schematic top view showing an example of a second sheet used in the lamination process. Figure 12 is a schematic top view showing an example of the lamination process. Figure 13 is a schematic top view showing an example of the sealing process. Figure 14 is a schematic top view showing the cutting positions to be cut in the individualization process. Figure 15 is a schematic cross-sectional view showing the cutting positions to be cut in the individualization process. Figure 16 is a schematic top view showing another example of a first sheet used in the lamination process. Figure 17 is a schematic top view showing another example of a second sheet used in the lamination process. Figure 18 is a schematic top view showing another example of the lamination process. Figure 19 is a schematic top view showing another example of the sealing process. Figure 20 is a schematic top view showing the cutting positions to be cut in the individualization process. Figure 21 is a schematic cross-sectional view showing the cutting positions to be cut in the individualization process. Figure 22 is a schematic top view illustrating yet another example of the lamination process.

[0012] The present invention, including its solid electrolytic capacitor and method for manufacturing the solid electrolytic capacitor, will now be described. However, the present invention is not limited to the configuration described below, and may be modified as appropriate without departing from the spirit of the invention. Furthermore, a combination of several of the preferred configurations described below also constitutes the present invention.

[0013] The following diagrams are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product. The same reference numerals are used for identical or equivalent parts in the diagrams. Furthermore, identical elements are denoted by the same reference numerals in each diagram, and redundant explanations are omitted.

[0014] In this specification, terms describing relationships between elements (e.g., "opposing," "orthogonal," etc.) and terms describing the shapes of elements mean not only their literal and precise forms, but also a range that is substantially equivalent, for example, a range that includes differences of a few percent.

[0015] The embodiments described below are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. In the description of each embodiment, descriptions of matters common to embodiments already described will be omitted, and only the differences will be described. In particular, similar effects and advantages due to similar configurations will not be mentioned sequentially for each embodiment.

[0016] [Solid Electrolytic Capacitor] The solid electrolytic capacitor of the present invention comprises a valve-acting metal substrate having a dielectric layer on at least one main surface, a solid electrolyte layer provided on the dielectric layer, and a cathode foil provided on the solid electrolyte layer, and is a substantially rectangular parallelepiped solid electrolytic capacitor having a first main surface and a second main surface facing each other in the stacking direction, a first side surface and a second side surface facing each other in the width direction perpendicular to the stacking direction, and a first end surface and a second end surface facing each other in the length direction perpendicular to the stacking direction and the width direction, wherein the first end surface is provided with a first external electrode electrically connected to the valve-acting metal substrate, and the second end surface is provided with a second external electrode electrically connected to the cathode foil, and the distance d from the side surface in the width direction to the valve-acting metal substrate is at least one of the first side surface and the second side surface. １ The distance d from the above-mentioned side surface to the above-mentioned cathode foil. ２ They are different.

[0017] Figure 1 is a schematic perspective view showing an example of the solid electrolytic capacitor of the present invention.

[0018] As shown in Figure 1, the solid electrolytic capacitor 1 has a base body 100, a first external electrode 50, and a second external electrode 60.

[0019] The base body 100 has a substantially rectangular parallelepiped shape, with a first main surface 100a and a second main surface 100b facing each other in the stacking direction (indicated by arrow T in Figure 1), a first side surface 100c and a second side surface 100d facing each other in the width direction perpendicular to the stacking direction (indicated by arrow W in Figure 1), and a first end surface 100e and a second end surface 100f facing each other in the length direction perpendicular to the stacking direction and the width direction (indicated by arrow L in Figure 1). The first side surface 100c and the second side surface 100d of the base body 100 are provided with a first insulating layer 40 and a second insulating layer 41, respectively. The first insulating layer 40 and the second insulating layer 41 are also called side margins.

[0020] The first external electrode 50 covers the entire first end face 100e of the base body 100, and, continuously from the first end face 100e, a part of the first main surface 100a, a part of the second main surface 100b, a part of the first insulating layer 40, and a part of the second insulating layer 41.

[0021] The second external electrode 60 covers the entire second end face 100f of the base body 100, and, continuously from the second end face 100f, a part of the first main surface 100a, a part of the second main surface 100b, a part of the first insulating layer 40, and a part of the second insulating layer 41.

[0022] The first main surface 1a and the second main surface 1b of the solid electrolytic capacitor 1 facing the stacking direction T correspond to the first main surface 100a and the second main surface 100b of the base body 100. The first side surface 1c and the second side surface 1d of the solid electrolytic capacitor 1 facing the width direction W correspond to the surface of the first insulating layer 40 and the surface of the second insulating layer 41. The first end surface 1e and the second end surface 1f of the solid electrolytic capacitor 1 facing the length direction L correspond to the surface of the first external electrode 50 covering the first end surface 100e of the base body 100 and the surface of the second external electrode 60 covering the second end surface 100f of the base body 100.

[0023] The materials constituting the first insulating layer 40 and the second insulating layer 41 (hereinafter collectively referred to as the insulating layers) include, for example, insulating resins such as polyimide resin and epoxy resin, and BaTiO ３ Examples include dielectric ceramic materials whose main components are the above. The insulating layer may also contain fillers in addition to the insulating layer resin and dielectric ceramic material.

[0024] The thickness of the insulating layer is not particularly limited, but it is preferably 5 μm or more and 40 μm or less, and more preferably 5 μm or more and 20 μm or less. Furthermore, it is preferable that the thickness of the insulating layer be 1% or more and 10% or less of the dimensions of the solid electrolytic capacitor in the width direction W (distance from the first side surface to the second side surface).

[0025] The first external electrode 50 and the second external electrode 60 can be formed, for example, by plating, sputtering, immersion coating, printing, etc. In the case of plating, the plating layers can be a Zn-Ag-Ni layer, an Ag-Ni layer, a Ni layer, a Zn-Ni-Au layer, a Ni-Au layer, a Zn-Ni-Cu layer, a Ni-Cu layer, etc. It is preferable to further form plating layers on these plating layers in the order of, for example, a Cu plating layer, a Ni plating layer, and a Sn plating layer (or with some exceptions).

[0026] The first external electrode 50 and the second external electrode 60 may be resin electrodes containing Ag or Cu. Furthermore, lead terminals may be connected to the first external electrode 50 and the second external electrode 60.

[0027] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. As shown in Figure 2, the base body 100 comprises a valve-acting metal substrate 11 having a dielectric layer 12 on at least one main surface, a solid electrolyte layer 13 provided on the dielectric layer 12, and a cathode foil 21 provided on the solid electrolyte layer 13, and the entire body is covered with a sealing resin 30.

[0028] The valve-acting metal substrate 11 has a porous portion (not shown) on at least one main surface, and a dielectric layer 12 is present on the surface of the porous portion. The valve-acting metal substrate 11, the porous portion, and the dielectric layer 12 are collectively referred to as the first layer 10 (first sheet 10). The cathode foil 21 is also referred to as the second layer 20 (second sheet 20). In other words, the base body 100 is constructed by alternately stacking the first layer 10 (first sheet 10) and the second layer 20 (second sheet 20) with a solid electrolyte layer 13 in between.

[0029] The valve-acting metal substrate 11 is exposed at the first end face 100e of the base body 100 and is electrically connected to the first external electrode 50. The cathode foil 21 is exposed at the second end face 100f of the base body 100 and is electrically connected to the second external electrode 60.

[0030] The valve-acting metal substrate 11 is made of a valve-acting metal that exhibits so-called valve action. Examples of valve-acting metals include elemental metals such as aluminum, tantalum, niobium, titanium, and zirconium, or alloys containing these metals. Among these, aluminum or aluminum alloys are preferred.

[0031] The shape of the valve metal substrate 11 is preferably flat, and more preferably foil-shaped. The porous portion can be formed by etching the surface of the valve metal substrate 11, or by printing the same or a different type of valve metal powder as the valve metal substrate 11 onto the surface of the valve metal substrate 11 and sintering as necessary. When the valve metal is aluminum or an aluminum alloy, it is preferable to form the porous portion by etching, and when the valve metal is any other, it is preferable to form the porous portion by printing the valve metal powder and sintering as necessary.

[0032] The thickness of the valve-acting metal substrate 11 is not particularly limited, but the thickness of the portion excluding the porous part is preferably 5 μm or more and 100 μm or less. Furthermore, the thickness of the porous part (thickness on one side) is preferably 5 μm or more and 200 μm or less.

[0033] The dielectric layer 12 formed on the surface of the porous portion is porous, reflecting the surface state of the porous portion, and has a fine, uneven surface shape. Preferably, the dielectric layer 12 is made of an oxide film of the valve-acting metal.

[0034] Examples of materials constituting the solid electrolyte layer 13 include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene) called PEDOT is particularly preferred. Furthermore, the conductive polymer may contain dopants such as polystyrene sulfonic acid (PSS).

[0035] The cathode foil 21 can be a metal foil made of at least one metal selected from the group consisting of aluminum, copper, silver, and alloys mainly composed of these metals. When the cathode foil 21 is made of the above metal foil, the resistance value of the cathode foil can be reduced, and the ESR can be reduced.

[0036] Furthermore, as the cathode foil 21, a metal foil with a carbon coating or titanium coating applied to its surface by a film deposition method such as sputtering or vapor deposition may be used.

[0037] The thickness of the cathode foil 21 is not particularly limited, but from the viewpoint of reducing ESR, it is preferably 5 μm or more and 100 μm or less.

[0038] It is preferable that a roughened surface is formed on the surface of the cathode foil 21. When a roughened surface is formed on the surface of the cathode foil 21, the adhesion between the cathode foil 21 and the solid electrolyte layer 13, or the adhesion between the cathode foil 21 and other conductive layers is improved, and the contact area is increased, thereby reducing ESR. The method for forming the roughened surface is not particularly limited, and the roughened surface may be formed by etching or the like. In particular when using aluminum, it is preferable to apply a carbon coating or titanium coating to a surface that has been roughened (etched) in order to reduce resistance.

[0039] Furthermore, a coating layer made of an anchor coating agent may be formed on the surface of the cathode foil 21. When a coating layer made of an anchor coating agent is formed on the surface of the cathode foil 21, the adhesion between the cathode foil 21 and the solid electrolyte layer 13, or the adhesion between the cathode foil 21 and other conductive layers is improved, thereby reducing ESR.

[0040] Examples of the sealing resin 30 include, for example, epoxy resins, phenolic resins, etc. The sealing resin 30 may contain a filler. Examples of the filler include metal oxide particles such as silica particles and alumina particles, etc.

[0041] The number of sheets (number of laminations) of the first sheet and the second sheet to be laminated is not particularly limited. Also, the number of laminations of the first sheet and the number of laminations of the second sheet may be different.

[0042] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. In the solid electrolytic capacitor 1, the distance d from the side surface in the width direction W to the valve action metal substrate 11 １ and the distance d from the same side surface to the cathode foil 21 ２ are different. Specifically, the distance d １ (d １１ ) from the first side surface 1c in the width direction W to the valve action metal substrate 11 is smaller than the distance d ２ (d １２ ) from the first side surface 1c to the cathode foil 21.

[0043] The distance d from the side surface in the width direction to the valve action metal substrate １ is equal to the distance d from the same side surface to the cathode foil ２ When they are equal, the position of the end portion of the valve action metal substrate in the width direction (simply referred to as the end portion of the valve action metal substrate) and the position of the end portion of the cathode foil in the width direction (simply referred to as the end portion of the cathode foil) are shifted in the lamination direction, but they coincide in the width direction. Therefore, the distance between the end portion of the valve action metal substrate and the end portion of the cathode foil is equal to the distance between the valve action metal substrate and the cathode foil in the lamination direction.

[0044] On the other hand, the distance d １ from the side surface in the width direction to the valve action metal substrate is the distance d ２If this is not the case, the ends of the valve metal substrate and the cathode foil will be offset not only in the stacking direction but also in the width direction. Therefore, the distance between the end of the valve metal substrate and the end of the cathode foil will be the sum of the offset between the ends of the valve metal substrate and the cathode foil in the stacking direction (offset in the stacking direction) and the offset between the ends of the valve metal substrate and the cathode foil in the width direction (offset in the width direction), and will be longer than the distance between the valve metal substrate and the cathode foil in the stacking direction.

[0045] Migration tends to occur where electric field lines are concentrated, and in the case of solid electrolytic capacitors, it is likely to occur between the edge of the valve-acting metal substrate and the edge of the cathode foil adjacent in the stacking direction. As described above, the distance d from the side surface in the width direction to the valve-acting metal substrate １ However, the distance d from the same side to the cathode foil ２ If it differs from this, the distance d from the side to the valve-acting metal substrate is... １ However, the distance d from the same side to the cathode foil ２ Compared to the case where the values ​​are equal, the distance between the ends where electric field lines are concentrated is longer, making migration less likely. In addition, the longer distance between the ends where electric field lines are concentrated makes the system less susceptible to the effects of migration. As a result, performance degradation caused by migration can be prevented.

[0046] Furthermore, in the solid electrolytic capacitor 1 shown in Figure 3, the distance d from the second side surface 1d of the solid electrolytic capacitor 1 to the valve-acting metal substrate 11 in the width direction W is １ (d ２１ ) and the distance d from the second side surface 1d to the cathode foil 21 ２ (d ２２ ) is different. Specifically, the distance d from the second side surface 1d in the width direction W to the valve-acting metal base 11. １ (d ２１ ) is the distance d from the second side surface 1d to the cathode foil 21. ２ (d ２２ It is larger than ).

[0047] In other words, in the solid electrolytic capacitor 1 shown in Figure 3, the distance d from the side surface in the width direction W to the valve-acting metal substrate 11 is such that on both the first side surface 1c and the second side surface 1d １ The distance d from the same side to the cathode foil 21 ２ The difference is that, on both the first and second side surfaces, the distance d from the side surface in the width direction to the valve-acting metal substrate is different. １ The distance d from the same side to the cathode foil. ２ If these two factors are different, then characteristic degradation due to migration can be prevented in both the first and second aspects.

[0048] In the solid electrolytic capacitor of the present invention, the distance d from the side surface in the width direction to the valve-acting metal substrate is １ The distance d from the same side to the cathode foil. ２ The absolute value of the difference is preferably 50 μm or more. If the difference between the distance from the side surface to the valve-acting metal substrate and the distance from the side surface to the cathode foil in the width direction is within the above range, the distance between the valve-acting metal substrate and the cathode foil becomes sufficiently large, so that characteristic degradation due to migration can be particularly suppressed.

[0049] Next, the positional relationship between the valve-acting metal substrate and cathode foil constituting the solid electrolytic capacitor shown in Figures 1, 2, and 3, when viewed from the stacking direction, will be explained with reference to Figures 4 to 6.

[0050] Figure 4 is a schematic diagram showing the positions of the valve-acting metal substrate and cathode foil that constitute the solid electrolytic capacitor shown in Figure 1, superimposed on the outer shape of the base body.

[0051] As shown in Figure 4, the valve-acting metal substrate 11 is positioned to be exposed on the first side surface 100c and the first end surface 100e of the base body 100, but not on the second side surface 100d and the second end surface 100f. On the other hand, the cathode foil 21 is positioned to be exposed on the second side surface 100d and the second end surface 100f of the base body 100, but not on the first side surface 100c and the first end surface 100e.

[0052] Dimension W in the width direction W of the valve-acting metal substrate 11 １１ and dimension L in the longitudinal direction L１１ The dimension W in the width direction W of the cathode foil 21 is ２１ and dimension L in the longitudinal direction L ２１ Since it is almost identical, the center of gravity C of the valve-acting metal substrate 11 １１ and the center of gravity C of the cathode foil 21 ２１ It can be said that it is shifted diagonally with respect to the width direction W and the length direction L.

[0053] Figure 5 is a schematic diagram showing the position of the valve-acting metal substrate constituting the solid electrolytic capacitor shown in Figure 1 superimposed on the outer shape of the base body. As shown in Figure 5, the valve-acting metal substrate 11 is not provided at the positions exposed on the second side surface 100d and the second end surface 100f of the base body 100. Therefore, it can be said that the valve-acting metal substrate 11 has a first through-hole 15, which is an L-shaped through-hole that is exposed on the second side surface 100d and the second end surface 100f.

[0054] Figure 6 is a schematic diagram showing the position of the cathode foil constituting the solid electrolytic capacitor shown in Figure 1 superimposed on the outer shape of the base body. As shown in Figure 6, the cathode foil 21 is not provided at the positions exposed on the first side surface 100c and the first end surface 100e of the base body 100. Therefore, it can be said that the cathode foil 21 has a second through-hole 25, which is an L-shaped through-hole that is exposed on the first side surface 100c and the first end surface 100e.

[0055] Figure 7 is a schematic cross-sectional view showing another example of the solid electrolytic capacitor of the present invention. In the solid electrolytic capacitor 2 shown in Figure 7, a first insulating layer 40 and a second insulating layer 41 are provided on the first side surface 102c and the second side surface 102d of the base body 102, respectively.

[0056] Both the valve-acting metal substrate 11 and the cathode foil 21 are exposed on the first side surface 102c of the base body 102. Therefore, the distance d from the first side surface 2c of the solid electrolytic capacitor 2 to the valve-acting metal substrate 11 in the width direction W is... １１ The distance d from the first side surface 2c to the cathode foil 21. １２They are equal. On the other hand, the valve-acting metal substrate 11 is not exposed on the second side surface 102d of the element 102, but the cathode foil 21 is exposed. Therefore, the distance d from the second side surface 2d of the solid electrolytic capacitor 2 to the valve-acting metal substrate 11 in the width direction W is equal. ２１ The distance d from the second side surface 2d to the cathode foil 21 is the distance d ２２ This differs from the previous one. Specifically, the distance d from the second side surface 2d in the width direction W to the valve-acting metal base 11. １ (d ２１ ) is the distance d from the second side surface 2d to the cathode foil 21. ２ (d ２２ It is larger than ).

[0057] As shown in Figure 7, on one side of the solid electrolytic capacitor 2 (the second side 2d in Figure 7), the distance d from the side to the valve-acting metal substrate 11 is １ and the distance d from the side to the cathode foil 21 ２ If these are different, it is possible to prevent characteristic degradation caused by migration.

[0058] In the solid electrolytic capacitor 2, the dimensions W of the valve-acting metal substrate 11 in the width direction W １１ Rather, the dimensions W of the cathode foil 21 ２１ The center of gravity is increasing. Here, both the valve-acting metal substrate 11 and the cathode foil 21 are exposed on the first side surface 102c of the element 102, while only the cathode foil 21 is exposed on the second side surface 102d. Therefore, the center of gravity of the cathode foil 21 is closer to the second side surface 102d than the center of gravity of the valve-acting metal substrate. For this reason, the center of gravity of the valve-acting metal substrate 11 and the center of gravity of the cathode foil 21 are offset with respect to the width direction W. In addition, the positional relationship of the centers of gravity of the valve-acting metal substrate 11 and the cathode foil 21 in the length direction L that constitute the element 102 of the solid electrolytic capacitor 2 is the same as that of the solid electrolytic capacitor 1 shown in Figures 4 to 6, and the centers of gravity of the valve-acting metal substrate 11 and the cathode foil 21 are offset in the length direction. From the above, it can be said that in the solid electrolytic capacitor 2, the center of gravity of the valve-acting metal substrate 11 and the center of gravity of the cathode foil 21 are offset with respect to the width direction W and the length direction L.

[0059] Figure 8 is a schematic cross-sectional view showing yet another example of the solid electrolytic capacitor of the present invention. In the solid electrolytic capacitor 3 shown in Figure 8, a first insulating layer 40 and a second insulating layer 41 are provided on the first side surface 103c and the second side surface 103d of the base body 103, respectively. The valve-acting metal substrate 11 is exposed on both the first side surface 103c and the second side surface 103d of the base body 103. The cathode foil 21 is not exposed on either the first side surface 103c or the second side surface 103d of the base body 103. In the solid electrolytic capacitor 3, the dimensions W of the valve-acting metal substrate 11 in the width direction W １１ However, the dimensions W of the cathode foil 21 ２１ It can be said that it is longer than that. Therefore, the distance d from the first side surface 3c of the solid electrolytic capacitor 3 to the valve-acting metal substrate 11 in the width direction W is greater than that. １ (d １１ ) is the distance d from the first side surface 3c to the cathode foil 21. ２ (d １２ ) is smaller than the distance d from the second side surface 3d to the valve-acting metal substrate 11. １ (d ２１ ) is the distance d from the second side surface 3d to the cathode foil 21. ２ (d ２２ It is smaller than ). Therefore, similar to the solid electrolytic capacitor 1 shown in Figure 1, it is possible to prevent characteristic degradation caused by migration.

[0060] Note that d in the width direction W １１ and d １２ The difference and d ２１ and d ２２ The difference between them may be the same, or they may be different.

[0061] Figure 9 is a schematic cross-sectional view showing yet another example of the solid electrolytic capacitor of the present invention. In the solid electrolytic capacitor 4 shown in Figure 9, a first insulating layer 40 and a second insulating layer 41 are provided on the first side surface 104c and the second side surface 104d of the base body 104, respectively. The cathode foil 21 is exposed on both the first side surface 104c and the second side surface 104d of the base body 104. The valve-acting metal substrate 11 is not exposed on either the first side surface 104c or the second side surface 104d of the base body 104. In the solid electrolytic capacitor 4, the dimension W of the cathode foil 21 in the width direction W is２１ However, the dimensions W of the valve-acting metal base 11 １１ It can be said that it is longer than that. Therefore, the distance d from the first side surface 4c of the solid electrolytic capacitor 4 to the valve-acting metal substrate 11 in the width direction １ (d １１ ) is the distance d from the first side surface 4c to the cathode foil 21. ２ (d １２ ) is larger than the distance d from the second side surface 4d in the width direction to the valve-acting metal base 11. １ (d ２１ ) is the distance d from the second side surface 4d to the cathode foil 21. ２ (d ２２ This is larger than the value shown. Therefore, similar to the solid electrolytic capacitor 1 shown in Figure 1, it is possible to prevent characteristic degradation caused by migration.

[0062] [Method for Manufacturing a Solid Electrolytic Capacitor] The present invention provides a method for manufacturing a solid electrolytic capacitor, comprising: a lamination step of laminating a valve-acting metal substrate having a dielectric layer on its surface, a solid electrolyte layer, and a cathode foil to obtain a laminate of the valve-acting metal substrate, the solid electrolyte layer, and the cathode foil; and a fragmentation step of cutting the laminate to form individual pieces, wherein in the lamination step, the valve-acting metal substrate, the solid electrolyte layer, and the cathode foil are laminated such that a non-opposing region is formed where at least one of the valve-acting metal substrate and the cathode foil is not laminated when viewed from the lamination direction; and in the fragmentation step, the laminate is cut such that the cut surface obtained by cutting the non-opposing region becomes the side surface of the fragmented laminate.

[0063] (Lamination Process) In the lamination process, a valve-acting metal substrate having a dielectric layer on its surface, a solid electrolyte layer, and a cathode foil are laminated to obtain a laminate. At this time, the valve-acting metal substrate, the solid electrolyte layer, and the cathode foil are laminated such that a non-opposing region is formed where at least one of the valve-acting metal substrate and the cathode foil is not laminated when viewed from the lamination direction.

[0064] The laminate can be formed, for example, by preparing a sheet of valve-acting metal substrate with a dielectric layer on its surface (first sheet) and a sheet that will serve as a cathode foil (second sheet), and laminating them with a solid electrolyte layer in between.

[0065] An example of the procedure for preparing the first sheet in the lamination process will be explained with reference to Figure 10.

[0066] Figure 10 is a schematic top view showing an example of a first sheet used in the lamination process. The first sheet 10 shown in Figure 10 consists of a valve-acting metal substrate and a dielectric layer provided on its surface.

[0067] The first sheet 10 has an anode portion 10a, which is the part that ultimately constitutes the base body, and a support portion 10b, which is the part that supports the anode portion 10a during the lamination process. The support portion 10b extends along the width direction W. At one end of the support portion 10b in the length direction L (the -L direction in Figure 10), a plurality of anode portions 10a extending along the length direction L are arranged.

[0068] Note that in Figure 10, the dotted lines shown between the support portion 10b and the anode portion 10a, and between the anode portions 10a themselves, are for visually indicating these boundaries and do not represent perforations or anything similar formed on the first sheet 10.

[0069] In the first sheet 10, multiple anode portions 10a are arranged along the width direction W, but each of the multiple anode portions 10a is divided into pairs by a slit-shaped through portion (first through portion 15). In other words, when considering one anode portion 10a, it is adjacent to the other anode portion 10a in the width direction W via the first through portion 15, and is directly adjacent to the other anode portion 10a in the width direction W without the first through portion 15. A valve-acting metal substrate is not placed in the portion where the first through portion 15 is provided.

[0070] The shape of the first penetration portion 15 is not particularly limited, but it is preferable that the first sheet 10 is not exposed at one end face and one side face of the base portion 15 when a region that will become a solid electrolytic capacitor after the individualization process (the region F enclosed by the dashed line in Figure 10, also called the base region) is set up.

[0071] An example of a shape in which the first sheet 10 is not exposed at one end face and one side face of the base region F is a shape in which an L-shaped through portion is provided that is in contact with a position corresponding to either one end face and either one side face of the base region F. In this case, the anode portion 10a of the first sheet 10 and the base region F do not perfectly coincide, and the area consisting of the anode portion 10a and the through portion corresponds to the base region F.

[0072] In the first sheet 10 shown in Figure 10, the first penetration portion 15 is a straight slit, but the base region F is set as a region on the opposite side of the support portion 10b, starting from the boundary between the support portion 10b and the anode portion 10a, where the length in the longitudinal direction L exceeds the length of the anode portion 10a. That is, when looking at the base region F, regions where the first sheet 10 (valve-acting metal substrate) is not provided are formed at one end in the width direction W and at the end in the longitudinal direction L opposite to the support portion 10b. The shape of the region in the base region F where the first sheet 10 is not provided is an L-shape that is in contact with a position corresponding to either one end face of the anode portion 10a in the base region F and a position corresponding to either one side surface.

[0073] The first sheet 10 is preferably manufactured as follows. First, a valve-acting metal substrate having a porous portion on its surface is prepared, and a dielectric layer is formed on the surface of the porous portion. For example, when aluminum foil is used as the valve-acting metal substrate, a dielectric layer consisting of an oxide film can be formed by performing an anodic oxidation treatment (also called a chemical conversion treatment) on the surface of the aluminum foil in an aqueous solution containing ammonium adipate or the like.

[0074] The valve-acting metal substrate consists of a valve-acting metal that exhibits so-called valve action. Examples of valve-acting metals include elemental metals such as aluminum, tantalum, niobium, titanium, and zirconium, or alloys containing these metals. Among these, aluminum or aluminum alloys are preferred.

[0075] The shape of the valve metal substrate is preferably flat, and more preferably foil-shaped. The porous portion can be formed by etching the surface of the valve metal substrate, or by printing valve metal powder of the same or different type as the valve metal substrate onto the surface of the valve metal substrate and sintering as necessary. When the valve metal is aluminum or an aluminum alloy, it is preferable to form the porous portion by etching, and when the valve metal is any other, it is preferable to form the porous portion by printing valve metal powder and sintering as necessary.

[0076] The thickness of the valve-acting metal substrate is not particularly limited, but the thickness of the portion excluding the porous part is preferably 5 μm or more and 100 μm or less. Furthermore, the thickness of the porous part (thickness on one side) is preferably 5 μm or more and 200 μm or less.

[0077] The dielectric layer formed on the surface of the porous portion is porous, reflecting the surface state of the porous portion, and has a fine, uneven surface shape. Preferably, the dielectric layer is made of an oxide film of the valve-acting metal.

[0078] Furthermore, from the viewpoint of improving manufacturing efficiency, a chemical conversion foil that has been pre-treated with chemical conversion may be used as the valve-acting metal substrate on which the dielectric layer is formed on the surface.

[0079] Next, a solid electrolyte layer is formed on the dielectric layer. For example, a solid electrolyte layer can be formed in a predetermined area by applying the following processing liquid or dispersion onto the dielectric layer using a sponge transfer, screen printing, dispenser, inkjet printing, etc.

[0080] The solid electrolyte layer is formed, for example, by using a treatment solution containing a monomer such as 3,4-ethylenedioxythiophene to form a polymerized film such as poly(3,4-ethylenedioxythiophene) on the surface of the dielectric layer, or by applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer and drying it. It is preferable to form the solid electrolyte layer by first forming an inner layer that fills the pores (recesses) of the dielectric layer, and then forming an outer layer that covers the dielectric layer.

[0081] Examples of materials constituting the solid electrolyte layer include conductive polymers such as polypyrroles, polythiophenes, and polyanilines. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene) called PEDOT is particularly preferred. Furthermore, the conductive polymer may contain dopants such as polystyrene sulfonic acid (PSS).

[0082] The overall size of the first sheet is determined by the size, shape, number, arrangement, and production capacity of the base material areas, and is not particularly limited. The shape of the base material areas of the first sheet is not particularly limited, but is preferably rectangular. In this case, the first and second ends may be shorter or longer than the first and second sides.

[0083] Methods for forming a through portion (first through portion) in the valve-acting metal substrate include punching and cutting with a dicer. It is preferable to form the first through portion on the first sheet after forming a solid electrolyte layer on the dielectric layer.

[0084] Next, an example of the procedure for preparing the second sheet in the lamination process will be explained with reference to Figure 11.

[0085] Figure 11 is a schematic top view showing an example of a second sheet used in the lamination process. The second sheet 20 shown in Figure 11 is composed of cathode foil.

[0086] The second sheet 20 has a cathode portion 20a, which is the part that ultimately constitutes the base body, and a support portion 20b, which is the part that supports the cathode portion 20a during the lamination process. The support portion 20b extends along the width direction W. At one end of the support portion 20b in the length direction L (the +L direction in Figure 11), a plurality of cathode portions 20a extending along the length direction L are arranged.

[0087] Note that the dotted lines shown in Figure 11 between the support portion 20b and the cathode portion 20a, and between the cathode portions 20a themselves, are for visual indication of these boundaries and do not represent perforations or anything similar formed on the second sheet 20.

[0088] In the second sheet 20, multiple cathode portions 20a are arranged along the width direction W, but each of the multiple cathode portions 20a is divided into pairs by a slit-shaped through portion (second through portion 25). In other words, when focusing on one cathode portion 20a, it is adjacent to the other cathode portion 20a in the width direction W via the second through portion 25, and is directly adjacent to the other cathode portion 20a in the width direction W without the second through portion 25. No cathode foil is placed in the portion where the second through portion 25 is provided.

[0089] The second sheet 20 is made of metal foil.

[0090] The metal foil is preferably made of at least one metal selected from the group consisting of aluminum, copper, silver, and alloys mainly composed of these metals. When the metal foil is made of the above metals, the resistance value of the metal foil can be reduced, and the ESR can be reduced.

[0091] Furthermore, metal foils with a carbon coating or titanium coating applied to the surface by film deposition methods such as sputtering or vapor deposition may also be used.

[0092] The thickness of the metal foil is not particularly limited, but from the viewpoint of reducing ESR, it is preferable that it be between 5 μm and 100 μm.

[0093] It is preferable that a roughened surface is formed on the surface of the metal foil. When a roughened surface is formed on the surface of the metal foil, the adhesion between the metal foil and the solid electrolyte layer, or between the metal foil and other conductive layers, is improved, and the contact area is increased, thereby reducing ESR. The method for forming the roughened surface is not particularly limited, and it may be formed by etching or the like. In particular when using aluminum, it is preferable to apply a carbon coating or titanium coating to a surface that has been roughened (etched) in order to reduce resistance.

[0094] Furthermore, a coating layer made of an anchor coating agent may be formed on the surface of the metal foil. When a coating layer made of an anchor coating agent is formed on the surface of the metal foil, the adhesion between the metal foil and the solid electrolyte layer, or the adhesion between the metal foil and other conductive layers, is improved, thereby reducing ESR.

[0095] The overall size of the second sheet is not particularly limited, but it is preferable that it be the same as the overall size of the first sheet. The shape, number, and arrangement of the base area regions of the second sheet are preferably the same as the shape, number, and arrangement of the base area regions of the opposing first sheet.

[0096] As a method for forming a through portion (second through portion) in the metal foil which is the second sheet 20, the same method as the method for forming a through portion (first through portion) in the first sheet can be used.

[0097] The shape of the second penetration portion 25 is not particularly limited, but it is preferable that the second sheet 20 is not exposed at one end face and one side face of the base body of the base body region F (the region F enclosed by the dashed line in Figure 11, also called the base body region) when a region that will constitute a single solid electrolytic capacitor after the individualization process is set.

[0098] An example of a shape in which the second sheet 20 is not exposed at one end face and one side face of the base region F is a shape in which an L-shaped through portion is provided that is in contact with a position corresponding to either one end face and either one side face of the base region F. In this case, the cathode portion 20a of the second sheet 20 and the base region F do not perfectly coincide, and the area consisting of the cathode portion 20a and the through portion corresponds to the base region F.

[0099] In the second sheet 20 shown in Figure 11, the second penetration portion 25 is a straight slit, but the base region F is set as a region on the opposite side of the support portion 20b, starting from the boundary between the support portion 20b and the cathode portion 20a, where the length in the length direction L exceeds the length of the cathode portion 20a. That is, when looking at the base region F, regions where the second sheet 20 (cathode foil) is not provided are formed at one end in the width direction W and at the end in the length direction L opposite to the support portion 20b. The shape of the region in the base region F where the second sheet 20 is not provided is an L-shape that is in contact with a position corresponding to either one end face of the cathode portion 20a in the base region F and a position corresponding to either one side surface.

[0100] In this specification, "penetration portion" refers to a portion where, in the case of the first sheet, the valve-acting metal substrate is absent throughout the entire thickness direction (lamination direction), and in the case of the second sheet, the cathode foil is absent throughout the entire thickness direction (lamination direction). This includes "notches" formed by cutting out a part of the side surface of the first sheet or the second sheet, and "punched portions" formed by punching the first sheet or the second sheet.

[0101] An example of the process of laminating the first sheet and the second sheet in the lamination process will be explained with reference to Figure 12.

[0102] Figure 12 is a schematic top view showing an example of the lamination process. The first sheet 10 and the second sheet 20 are arranged such that their support portions 10b and 20b are on opposite sides in the length direction L, and their anode portion 10a and cathode portion 20a overlap each other.

[0103] Since the first sheet 10 is composed of a valve-acting metal substrate on at least one of its main surfaces, in Figures 12 to 14, the region where the first sheet 10 is arranged (laminated) is the region where the valve-acting metal substrate is arranged (laminated). Similarly, since the second sheet 20 is composed of cathode foil, in Figures 12 to 14, the region where the second sheet 20 is arranged (laminated) is the region where the cathode foil is arranged (laminated).

[0104] As shown in Figure 12, the first through-hole 15 and the second through-hole 25 do not overlap. The second through-hole 25 overlaps between two anode portions 10a that are not separated by the first through-hole 15, and the first through-hole 15 overlaps between two cathode portions 20a that are not separated by the second through-hole 25.

[0105] The region where the first through-port 15 and the second sheet 20 are laminated is the non-laminated region A of the valve-acting metal substrate, where the first through-port 15 of the valve-acting metal substrate and the portion of the cathode foil other than the second through-port 25 (here, the cathode portion 20a) are laminated. ２ That is the case.

[0106] The region where the first sheet 10 and the second through portion 25 are laminated is the cathode foil non-laminated region A, where the portion of the valve-acting metal substrate other than the first through portion 15 (in this case, the anode portion 10a) and the second through portion 25 of the cathode foil are laminated together. １ That is the case.

[0107] In other words, in Figure 12, the non-opposing region is the non-laminated region A of the valve-acting metal substrate. ２ and cathode foil non-laminated region A １ The first sheet 10 and the second sheet 20 are stacked so that a structure is formed.

[0108] Figure 13 is a schematic top view showing an example of the sealing process. As shown in Figure 13, the anode portion 10a and the cathode portion 20a are sealed with sealing resin. At this time, the first through portion 15 provided in the first sheet 10 and the second through portion 25 provided in the second sheet 20 are filled with sealing resin 30. A laminate L1 is obtained by the above procedure.

[0109] (Individualization process) In the individualization process, the laminate L1 is cut into individual pieces. In the individualization process, the laminate L1 is cut such that the cut surface obtained by cutting the non-facing region becomes the side surface of the individualized laminate L1.

[0110] The method for cutting the laminate L1 is not particularly limited, but examples include cutting with a dicer, router, laser cutter, or guillotine blade. Ultrasonic vibration may also be applied when cutting with a guillotine blade.

[0111] Figure 14 is a schematic top view showing the cutting positions in the individualization process. Figure 15 is a schematic cross-sectional view showing the cutting positions in the individualization process.

[0112] As shown in Figure 14, the laminate L1 is cut along the width direction W along the dashed line. Specifically, the first sheet 10 is cut along the width direction W so as to separate the anode portion 10a of the first sheet 10 from the support portion 10b, and the second sheet 20 is cut along the width direction so as to separate the cathode portion 20a of the second sheet 20 from the support portion 20b.

[0113] The first sheet 10 is cut along the width direction W so as to separate the anode portion 10a of the first sheet 10 from the support portion 10b, and the resulting cut surface becomes the first end surface where the valve-acting metal substrate is exposed. The second sheet 20 is cut along the width direction W so as to separate the cathode portion 20a of the second sheet 20 from the support portion 20b, and the resulting cut surface becomes the second end surface where the cathode foil is exposed.

[0114] Next, as shown in Figures 14 and 15, the laminate L1 is cut along the length L along the dashed line. Specifically, the cathode foil non-laminated region A １ and valve-acting metal substrate non-laminated region A ２ The laminate is cut along the length direction L at a point that divides it into two equal parts in the width direction W. The cut surface at this point is considered the side surface (the surface facing the width direction W) of the individual laminated body L1.

[0115] Valve-acting metal substrate non-layered region A ２ When cutting, the sealing resin 30 filled in the first through portion 15 of the valve-acting metal substrate 11 and the cathode foil 21 are cut alternately. Therefore, the valve-acting metal substrate 11 is not cut. In other words, the non-laminated region A of the valve-acting metal substrate ２ The valve-acting metal substrate 11 is not exposed on the cut surface. Therefore, the non-laminated region A of the valve-acting metal substrate. ２ When the cut surface obtained by cutting is considered the side surface, the distance d from the side surface in the width direction to the cathode foil 21 is ２ However, the distance d from the side to the valve-acting metal base 11 １ It will become smaller than that.

[0116] Note that distance d １ and d２ The magnitude relationship remains unchanged even when an insulating layer is formed on the side surface of the fragmented laminate (element body).

[0117] Cathode foil non-laminated region A １ When cutting, the sealing resin 30 filled in the second through-hole 25 of the cathode foil 21 and the valve-acting metal substrate 11 are alternately cut. Therefore, the cathode foil 21 is not cut. In other words, the cathode foil non-laminated region A １ The cathode foil 21 is not exposed on the cut surface obtained by cutting. Therefore, the cathode foil non-laminated region A １ When the cut surface obtained by cutting is used as the side surface, the distance d from the side surface in the width direction to the valve-acting metal substrate 11 １ is smaller than the distance d from the side surface to the cathode foil 21 ２ . Note that, similar to the case of cutting the valve-acting metal substrate non-laminated region A ２ , the magnitude relationship of the distances d １ and d ２ remains unchanged even when an insulating layer is formed on the side surface of the fragmented laminate L1 (element body).

[0118] When neither the valve-acting metal substrate 11 nor the cathode foil 21 is exposed on the cut surface, even if a cut sag occurs on one of the valve-acting metal substrate 11 and the cathode foil 21 due to cutting, it will not contact the other. Therefore, there is no need to perform cutting (fragmentation) under mild conditions to suppress cut sag, and the production efficiency is improved. Furthermore, since the occurrence of cut sag is allowed, the width of the materials constituting the valve-acting metal substrate and the cathode foil can be widened, and for example, materials that are likely to cause cut sag but have good electrical characteristics or low costs can be adopted.

[0119] Through the above procedure, an element body 100 is obtained in which the valve-acting metal substrate 11 is exposed on the first end face and the first side face, and the cathode foil 21 is exposed on the second end face and the second side face.

[0120] By disposing the first insulating layer 40 and the second insulating layer 41 on the first side face 100c and the second side face 100d of the element body 100 obtained by the above procedure, respectively, and further forming the first external electrode 50 and the second external electrode 60 on the first end face 100e and the second end face 100f, respectively, the solid electrolytic capacitor 1 shown in FIG. 1 can be obtained.

[0121] As described above, the method for manufacturing a solid electrolytic capacitor of the present invention is useful as a method for manufacturing a solid electrolytic capacitor of the present invention.

[0122] The order of cutting in the width direction W and the length direction L with respect to the laminate L1 is not particularly limited, and the cutting in the length direction L may be performed first, followed by the cutting in the width direction W. Further, after performing the cutting in the length direction L, the first insulating layer and the second insulating layer described later may be formed on the cut surface, and then the cutting in the width direction W may be performed.

[0123] As another method for forming the non-facing region, for example, there is a method in which through-holes penetrating in the thickness direction are formed in the valve-acting metal substrate and the cathode foil, and the through-holes in the valve-acting metal substrate and the through-holes in the cathode foil are laminated so as to partially overlap. By laminating the through-holes in the valve-acting metal substrate and the through-holes in the cathode foil so as to partially overlap in the width direction, the cathode foil non-laminated region A １ and the valve-acting metal substrate non-laminated region A ２ not only, but also a completely non-laminated region A which is a region where neither the valve-acting metal substrate nor the cathode foil is laminated ０ can be formed.

[0124] Referring to FIGS. 16 to 21, an example of forming the completely non-laminated region A ０ will be described.

[0125] FIG. 16 is a top view schematically showing another example of the first sheet used in the lamination step. The first sheet 110 shown in FIG. 16 is composed of a valve-acting metal substrate and a dielectric layer provided on the surface thereof.

[0126] The first sheet 110 has an anode part 110a which is a part that finally constitutes the laminate, and a support part 110b which is a part that supports the anode part 110a in the lamination step. The support part 110b extends along the width direction W. A plurality of anode parts 110a extending along the length direction L are arranged at one end (in the -L direction in FIG. 16) in the length direction L of the support part 110b. A slit-shaped through-hole (first through-hole 115) is provided between the anode parts 110a in the width direction W. The valve-acting metal substrate is not arranged in the portion where the first through-hole 115 is provided.

[0127] Comparing the elemental region F, which becomes the elemental body that constitutes a single solid electrolytic capacitor after the individualization process, with the anode portion 110a, it can be said that the first sheet 110 (valve-acting metal substrate) is not arranged at both ends (both sides) of the anode portion 110a in the width direction W, and at one end of the anode portion 110a in the length direction L, and a U-shaped first through portion 115 is provided.

[0128] Figure 17 is a schematic top view showing another example of a second sheet used in the lamination process. The second sheet 120 shown in Figure 17 is composed of cathode foil. The second sheet 120 has a cathode portion 120a, which is the part that ultimately constitutes the laminate, and a support portion 120b, which is the part that supports the cathode portion 120a in the lamination process. The support portion 120b extends along the width direction W. At one end of the support portion 120b in the length direction L (the +L direction in Figure 17), a plurality of cathode portions 120a extending along the length direction L are arranged. Between each cathode portion 120a in the width direction W, a slit-shaped through portion (second through portion 125) is provided. No cathode foil is arranged in the portion where the second through portion 25 is provided.

[0129] Comparing the elemental region F, which becomes the elemental body that constitutes a single solid electrolytic capacitor after the individualization process, with the cathode portion 120a, it can be said that the second sheet 120 (cathode foil) is not placed at both ends (both sides) of the cathode portion 120a in the width direction W, and at one end of the cathode portion 120a in the length direction L, and a U-shaped second through portion 125 is provided.

[0130] The length (width) of the cathode portion 120a and the length (width) of the second through portion 125 in the width direction W are the same as the length (width) of the anode portion 110a and the length (width) of the first through portion 115 in the width direction of the first sheet 110 shown in Figure 16.

[0131] Figure 18 is a schematic top view showing another example of the lamination process. As shown in Figure 18, the first sheet 110 and the second sheet 120 are arranged such that their support portions 110b and 120b are on opposite sides in the longitudinal direction L.

[0132] Since the first sheet 110 is composed of a valve-acting metal substrate having a dielectric layer on at least one main surface, in Figures 18 to 20, the region where the first sheet 110 is arranged (laminated) is the region where the valve-acting metal substrate is arranged (laminated). Similarly, since the second sheet 120 is composed of cathode foil, in Figures 18 to 20, the region where the second sheet 120 is arranged (laminated) is the region where the cathode foil is arranged (laminated).

[0133] The first through-section 115 and the second through-section 125 are arranged so as to partially overlap in the width direction W. As a result, in addition to the region where the first through-section 115 is stacked and the second through-section 125 is not stacked, and the region where the second through-section 125 is stacked and the first through-section 115 is not stacked, a region is formed in which both the first through-section 115 and the second through-section 125 are stacked.

[0134] The region where the first through portion 115 is laminated and the second through portion 125 is not laminated is the valve-acting metal substrate non-laminated region A. ２ The region where the second through-section 125 is laminated and the first through-section 115 is not laminated is the cathode foil non-laminated region A. １ The region where both the first through-section 115 and the second through-section 125 are laminated is a completely non-laminated region where neither the valve-acting metal substrate nor the cathode foil are laminated.

[0135] Therefore, by laminating the first sheet 110 and the second sheet 120 as described above, the cathode foil non-laminate region A is formed. １ and valve-acting metal substrate non-laminated region A ２ In addition, completely non-layered region A ０ And, completely non-layered region A ０ Adjacent cathode foil non-laminated region A １ and valve-acting metal substrate non-laminated region A ２ A non-opposing region consisting of these can be formed.

[0136] Figure 19 is a schematic top view showing another example of the sealing process. As shown in Figure 19, the anode portion 110a and the cathode portion 120a are sealed with sealing resin. At this time, the first through portion 115 provided in the first sheet 110 and the second through portion 125 provided in the second sheet 120 are filled with sealing resin 30. A laminate L2 is obtained by the above procedure.

[0137] Figure 20 is a schematic top view showing the cutting positions in the individualization process. Figure 21 is a schematic cross-sectional view showing the cutting positions in the individualization process.

[0138] As shown in Figure 20, the laminate L2 is cut along the width direction W along the dashed line. Specifically, the first sheet 110 is cut along the width direction W so as to separate the anode portion 110a of the first sheet 110 from the support portion 110b, and the second sheet 120 is cut along the width direction W so as to separate the cathode portion 120a of the second sheet 120 from the support portion 120b.

[0139] The first sheet 110 is cut along the width direction W so as to separate the anode portion 110a of the first sheet 110 from the support portion 110b, and the resulting cut surface becomes the first end surface where the valve-acting metal substrate is exposed. The second sheet 20 is cut along the width direction W so as to separate the cathode portion 20a of the second sheet 20 from the support portion 20b, and the resulting cut surface becomes the second end surface where the cathode foil is exposed.

[0140] Next, as shown in Figures 20 and 21, the laminate L2 is cut along the dashed line in the longitudinal direction L. Specifically, the completely non-laminated region A ０ The material is cut along the length direction L at a point that divides it in the width direction W into two equal parts. The cut surface at this point is considered the side surface (the surface facing the width direction W) of the individual laminated pieces.

[0141] Completely non-laminated area A ０When cutting, the sealing resin 30 filled in the first through-hole 115 of the first sheet 110 and the sealing resin 30 filled in the second through-hole 125 of the second sheet 120 are cut alternately and continuously. Therefore, the valve-acting metal substrate 11 and the cathode foil 21 are not cut. In other words, the valve-acting metal substrate 11 and the cathode foil 21 are not exposed at the cut surface.

[0142] As shown in Figure 21, when the individual laminated pieces after cutting are used as the base body 105, the distance from the side surface of the base body 105 to the valve-acting metal substrate 11 and the distance from the side surface to the cathode foil 21 are different. This is because, as shown in Figure 18, when the first sheet 110 and the second sheet 120 are laminated, the first through portion 115 and the second through portion 125 overlap only partially in the width direction W, resulting in a cathode foil non-laminated region A. １ and valve-acting metal substrate non-laminated region A ２ Adjacent to it is a completely non-layered region A ０ This is due to the formation of a completely non-layered region A. ０ Adjacent cathode foil non-laminated region A １ or valve-acting metal substrate non-laminated region A ２ A difference arises between the distance from the cross-section (end face) in the width direction W to the valve-acting metal substrate and the distance to the cathode foil, equal to the length W in the width direction.

[0143] In addition, since neither the valve-acting metal substrate 11 nor the cathode foil 21 is exposed at the cut surface, theoretically no cutting burr occurs. Therefore, it is no longer necessary to perform cutting (fractionation) under conditions that suppress cutting burr, and production efficiency is improved. Furthermore, since it is no longer necessary to consider the occurrence of cutting burr, the range of materials that can be used to constitute the valve-acting metal substrate and cathode foil is broadened, and for example, a material that is prone to cutting burr but has good electrical properties can be used.

[0144] After arranging the first insulating layer 40 and the second insulating layer 41 as needed on the first and second sides of the base body 105 obtained by the above procedure, and then forming the first external electrode 50 and the second external electrode 60 on the first end face 100e and the second end face 100f, respectively, the solid electrolytic capacitor of the present invention can be obtained.

[0145] The order in which the laminate L2 is cut in the width direction W and the length direction L is not particularly limited; the length direction L may be cut first, followed by the width direction W. Alternatively, after cutting in the length direction L, the first insulating layer and the second insulating layer, described later, may be formed on the cut surface, and then the width direction W may be cut.

[0146] In addition, while Figures 10 to 21 describe a method of stacking a first sheet and a second sheet in which the anode and cathode portions are arranged in only one row along the width direction, in the manufacturing method of the solid electrolytic capacitor of the present invention, the first sheet and the second sheet may be in which multiple anode and cathode portions are arranged along the length direction and the width direction.

[0147] An example of a lamination process in which a first sheet having multiple anode portions arranged in the longitudinal direction and a second sheet having multiple cathode portions arranged in the longitudinal direction are stacked will be explained with reference to Figure 22.

[0148] Figure 22 is a schematic top view showing yet another example of the lamination process. In the lamination process shown in Figure 22, a first sheet 210 and a second sheet 220 are laminated. In the first sheet 210, a support portion 10b extending along the width direction W and a plurality of anode portions 10a connected to the support portion 10b are arranged in multiple first sheets 10 along the width direction W and in the length direction L. Similarly, in the second sheet 220, a support portion 20b extending along the width direction W and a plurality of cathode portions 20a connected to the support portion 20b are arranged in multiple second sheets 20 along the width direction W and in the length direction L.

[0149] As shown in Figure 22, the multiple first sheets 10 that make up the first sheet 210 do not necessarily have to be consecutive. Similarly, the second sheets 20 that make up the second sheet 220 do not necessarily have to be consecutive.

[0150] However, from the viewpoint of improving the handling of the first sheet 210 and the second sheet 220 when stacked, an outer frame may be provided to stably hold each anode portion 10a and support portion 10b of the first sheet 210. Similarly, an outer frame may be provided to stably hold each cathode portion 20a and support portion 20b of the second sheet 220.

[0151] The shapes of the first sheet (valve-acting metal substrate) and the second sheet (cathode foil) that can be used in the method for manufacturing a solid electrolytic capacitor of the present invention are not particularly limited. For example, a first sheet may be formed by filling a planar surface with a valve-acting metal substrate of the shape shown in Figure 5 by forming an L-shaped through portion (first through portion), and a second sheet may be formed by filling a planar surface with a cathode foil of the shape shown in Figure 6 by forming an L-shaped through portion (second through portion).

[0152] 1, 2, 3, 4 Solid electrolytic capacitor 1a First main surface of solid electrolytic capacitor 1b Second main surface of solid electrolytic capacitor 1c First side surface of solid electrolytic capacitor 1d Second side surface of solid electrolytic capacitor 1e First end surface of solid electrolytic capacitor 1f Second end surface of solid electrolytic capacitor 10, 110, 210 First sheet 10a, 110a, 210a Anode part 10b, 110b, 210b Support part 11 Valve-acting metal substrate 12 Dielectric layer 13 Solid electrolyte layer 15, 115 First through-parts 20, 120, 220 Second sheet 20a, 120a, 220a Cathode part 20b, 120b, 220b Support part 21 Cathode foil 25, 125 Second through-parts 30 Sealing resin 40 First insulating layer 41 Second insulating layer 50 First external electrode 60 Second external electrode 100, 102, 103, 104, 105 Base body (laminated fragments) 100a First main surface of base body 100b Second main surface of base body 100c, 102c, 103c, 104c First side surface of base body 100d, 102d, 103d, 104d Second side surface of base body 100e First end surface of base body 100f Second end surface of base body A ０ Completely non-laminated area A １ Cathode foil non-layered region A ２ Valve-acting metal substrate non-layered region C１１ Center of gravity C of the valve-acting metal substrate ２１ Center of gravity of cathode foil d １ Distance d from the side to the valve-acting metal substrate １１ Distance d from the first side surface to the valve-acting metal substrate ２１ Distance d from the second side surface to the valve-acting metal substrate ２ Distance d from the side to the cathode foil １２ Distance d from the first side to the cathode foil ２２ Distance from the second side to the cathode foil F: Elemental region L1, L2: Laminate

Claims

1. A solid electrolytic capacitor having a substantially rectangular parallelepiped shape, comprising: a valve-acting metal substrate having a dielectric layer on at least one main surface; a solid electrolyte layer provided on the dielectric layer; and a cathode foil provided on the solid electrolyte layer, wherein the capacitor has a first main surface and a second main surface facing each other in the stacking direction, a first side surface and a second side surface facing each other in the width direction perpendicular to the stacking direction, and a first end surface and a second end surface facing each other in the length direction perpendicular to the stacking direction and the width direction, wherein the first end surface is provided with a first external electrode electrically connected to the valve-acting metal substrate, and the second end surface is provided with a second external electrode electrically connected to the cathode foil, and the distance d from the side surface in the width direction to the valve-acting metal substrate is at least one of the first side surface and the second side surface. １ and the distance d from the side surface to the cathode foil. ２ A solid electrolytic capacitor, which is different from the other.

2. On both the first and second side surfaces, the distance d from the side surface in the width direction to the valve-acting metal substrate. １ and the distance d from the side surface to the cathode foil. ２ A solid electrolytic capacitor according to claim 1, which differs from the above.

3. The distance d from the first side surface in the width direction to the valve-acting metal base. １１ However, the distance d from the first side surface to the cathode foil １２ Smaller than the distance d from the second side surface in the width direction to the valve-acting metal base. ２１ However, the distance d from the second side surface to the cathode foil ２２ A solid electrolytic capacitor according to claim 1 or 2, which is larger than the specified size.

4. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein, when viewed from the stacking direction, the center of the valve-acting metal substrate and the center of the cathode foil are offset with respect to the width direction and the length direction.

5. The distance d from the first side surface in the width direction to the valve-acting metal substrate １１ is smaller than the distance d from the first side surface to the cathode foil, and the distance d from the second side surface in the width direction to the valve-acting metal substrate １２ is smaller than the distance d from the second side surface to the cathode foil. The solid electrolytic capacitor according to claim 1 or 2. ２１ is smaller than the distance d from the second side surface to the cathode foil. The solid electrolytic capacitor according to claim 1 or 2. ２２ is smaller than the distance d from the second side surface to the cathode foil. The solid electrolytic capacitor according to claim 1 or 2.

6. The distance d from the first side surface in the width direction to the valve-acting metal base. １１ However, the distance d from the first side surface to the cathode foil １２ Larger than the distance d from the second side surface in the width direction to the valve-acting metal base. ２１ However, the distance d from the second side surface to the cathode foil ２２ A solid electrolytic capacitor that is larger than the one described in claim 1 or 2.

7. A method for manufacturing a solid electrolytic capacitor, comprising: a lamination step of laminating a valve-acting metal substrate having a dielectric layer on its surface and a cathode foil via a solid electrolyte layer to obtain a laminate of the valve-acting metal substrate, the solid electrolyte layer and the cathode foil; and a fragmentation step of cutting the laminate into individual pieces, wherein in the lamination step, the valve-acting metal substrate, the solid electrolyte layer and the cathode foil are laminated such that a non-opposing region is formed where at least one of the valve-acting metal substrate and the cathode foil is not laminated when viewed from the lamination direction; and in the fragmentation step, the laminate is cut such that the cut surface obtained by cutting the non-opposing region becomes the side surface of the fragmented laminate.

8. The method for manufacturing a solid electrolytic capacitor according to claim 7, wherein the valve-acting metal substrate and / or the cathode foil have through portions that penetrate in the thickness direction, and in the lamination step, the through portions of the valve-acting metal substrate and the portions of the cathode foil other than the through portions are laminated to form a non-laminated region of the valve-acting metal substrate where only the cathode foil is laminated when viewed from the lamination direction, and / or the portions of the valve-acting metal substrate other than the through portions and the through portions of the cathode foil are laminated to form a non-laminated region of the cathode foil where only the valve-acting metal substrate is laminated when viewed from the lamination direction, and in the piece-forming step, the laminate is cut such that the cut surfaces obtained by cutting the non-laminated region of the valve-acting metal substrate and / or the non-laminated region of the cathode foil become the sides of the piece-formed laminate.

9. The method for manufacturing a solid electrolytic capacitor according to claim 7, wherein the valve-acting metal substrate and the cathode foil have through portions that penetrate in the thickness direction, and in the lamination step, the laminates are formed such that the through portions of the valve-acting metal substrate and the through portions of the cathode foil overlap by only a portion, thereby forming a non-laminated region of the valve-acting metal substrate and / or a non-laminated region of the cathode foil where only the valve-acting metal substrate is laminated when viewed from the lamination direction, and a completely non-laminated region provided adjacent to the non-laminated region of the valve-acting metal substrate and / or the non-laminated region of the cathode foil, where neither the valve-acting metal substrate nor the cathode foil is laminated when viewed from the lamination direction, and in the piece-forming step, the laminate is cut such that the cut surface obtained by cutting the completely non-laminated region becomes the side surface of the piece-formed laminate.

Images