TWI423285B - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

Solid electrolytic capacitor and method of manufacturing same

This invention relates to a low ESR (Equivalent Series Resistance) high capacitance solid electrolytic capacitor. More specifically, it relates to a solid electrolytic capacitor having a low ESR and an increase in capacitance per unit volume and a method of manufacturing the same.

In recent years, with the digitization of electronic devices and the speed of personal computers, there is a need for a capacitor having a small size and a large capacitance, and a capacitor having a low impedance in a high frequency region. Recently, a solid electrolytic capacitor using a conductive polymer having electron conductivity as a solid electrolyte has been proposed.

In the method for producing a solid electrolytic capacitor (9), as shown in Fig. 1, a dielectric oxide film is formed on an anode substrate (1) composed of a metal foil or a thin plate having a large specific surface area. In the layer (2), a solid semiconductor layer (hereinafter referred to as a solid electrolyte) (3) is formed on the outer side thereof as a counter electrode, and a conductor layer (4) such as a conductive paste is formed to form a solid electrolytic capacitor element. Usually, a shielding layer (5) is additionally provided, and the electrode lead portions (6, 7) are appropriately added, and the resin (8) is integrally packaged to form a capacitor.

Although the above-mentioned conductor layer (4) mainly uses a silver paste, since silver tends to cause migration at a high temperature, generally, after the carbon paste layer (4a) containing carbon particles is provided, silver particles are formed. Silver paste layer (4b) (refer to Figure 2). These layers are formed by sequentially immersing in a liquid containing the components of each layer. However, in general, since the base of the capacitor element is in the form of a thin foil, as shown in Fig. 2, on the face and the side ( In the edge portion, the thickness of the formed silver paste layer (4b) is different. Specifically, the layer thickness of the edge (edge) portion tends to be small, and as a result, the ESR (equivalent series resistance) when the laminated capacitor is formed by laminating the capacitor element is liable to become large. Although it is also possible to apply a thick layer to the entire layer to increase the layer thickness of the side (edge) portion, in this case, since the thickness of the layer on the surface is also increased, the height of each element becomes large, and it is laminated. As a laminated capacitor, the capacitance per unit volume will decrease. Therefore, there is a need for a solid electrolytic capacitor in which a silver paste having a thickness of a layer (edge) portion is sufficiently ensured and a layer thickness on the surface is suppressed.

Further, when the side of the anode substrate is laminated with the oxide film layer, the conductive polymer layer, and the edge portion of the anode substrate of the carbon paste layer, the silver paste is applied, and the layers are laminated in this order. When the silver paste is applied by the immersion method in which the anode substrate is immersed in the silver paste and then pulled up, the silver paste adhering to the edge portion is thinner than the silver paste formed on the coated face portion. As a result, the electric resistance to the current flowing from the inner surface to the surface is higher than the current flowing in the plane of the anode substrate in the lateral direction. Therefore, compared with a solid electrolytic capacitor in which a silver paste is applied by a bristles, a solid electrolytic capacitor coated with a silver paste by a dipping method tends to have a high ESR.

On the other hand, when the silver paste is applied by the bristles, the thickness of the silver paste layer formed on the coated surface is uneven due to the bristles. In particular, when a silver paste containing a fluororesin is used, the thickness tends to become uneven. When the coating amount is increased in such a manner that no thin portion is generated, a thick portion of the silver paste layer higher than the required thickness is generated, and the number of solid electrolytic capacitor elements which can be sealed in the wafer having a certain height is reduced, so that the capacitance per unit volume is reduced. cut back.

Therefore, in the solid electrolytic capacitor in which the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste layer are sequentially laminated on the surface of the anode substrate composed of the valve action metal, it is necessary to have a carbon paste layer on the surface. A solid electrolytic capacitor in which the ESR (equivalent series resistance) of the laminated structure of the silver paste is sufficiently low and the capacitance per unit volume is increased is formed on the anode substrate.

Accordingly, an object of the present invention is to provide a solid electrolytic capacitor in which the ESR (equivalent series resistance) of the laminated structure in which the silver paste is formed on the anode substrate is sufficiently low and the capacitance per unit volume is increased.

As a result of intensive studies on the above-mentioned problems, the present inventors have found that a low ESR (equivalent series resistance) can be obtained by controlling the composition or layer thickness of a silver paste having a laminated structure formed on an anode substrate having a carbon paste layer on its surface. A solid electrolytic capacitor element with an increased capacitance per unit volume. In the present invention, the layer thickness of the side (edge) portion of the silver paste of the laminated structure and the layer thickness of the face portion can be controlled on the anode substrate. It has been found that when two kinds of silver paste compositions having different wettability to the carbon paste layer are used, if a component having a low wettability is applied to the edge (edge) portion, and a component having a high wettability is applied to the face, The desired layer thickness is then obtained overall. Further, it has been found that this phenomenon can be widely applied to the formation of a laminated structure of the first coating layer and the second coating layer in order. Further, it was found that a silver paste layer covering the side (edge) portion of the anode substrate having the carbon paste layer on the surface is a thicker ESR (equivalent series connection) than a solid electrolytic capacitor element having a thicker silver paste layer covering the surface of the anode substrate. A solid electrolytic capacitor element having a resistance and an increase in capacitance per unit volume. Further, it has been found that a solid electrolytic capacitor element having a lower ESR (equivalent series resistance) can be obtained from a solid electrolytic capacitor element in which a silver paste constituting a silver paste having a water content of 0.5% by mass or less is laminated. The present invention has been completed based on these findings.

When the silver paste is applied by the bristles, the thickness of the silver paste layer formed on the coated surface due to uneven bristles is not uniform. In order to increase the coating amount without generating a thinner portion, the silver paste layer may have a thicker portion than necessary, and the number of capacitor elements that can be sealed in the wafer at a certain height is reduced, and the capacitance per unit volume is reduced. Reduced problems.

On the other hand, when the silver paste is applied by the dipping method, the silver paste adhering to the side (edge) is thinner than the silver paste formed on the coated surface. As a result, the electrical resistance to the current flowing from the inner surface to the surface is higher as compared with the electrical phase flowing laterally in the plane of the anode substrate. Therefore, the capacitor coated by the dipping method has a problem that the ESR is high as compared with the capacitor in which the silver paste is applied by the bristles. Especially when a paste of a fluorine-containing resin is used, the thickness is easily uneven.

The present inventors have found that a solid electrolytic capacitor in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on a surface of an anode substrate composed of a valve action metal is covered with an anode substrate. The silver paste layer in the side (edge) portion is thicker than the silver paste layer covering the face portion, or the solid electrolytic capacitor having a thickness of the silver paste layer covering the side (edge) portion of the anode substrate of 10 μm or more can solve the above problem. The present invention has been completed.

The present inventors have found that a method of manufacturing a solid electrolytic capacitor in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on the surface of an anode substrate made of a valve action metal is used. The method comprises the steps of: immersing an anode substrate in which an oxide film layer, a conductive polymer layer and a carbon paste layer are sequentially laminated on a surface of an anode substrate in a silver paste; and coating a silver paste on the anode substrate side with a bristles ( The manufacturing method of the step of the edge portion can produce a capacitor having a small thickness unevenness of the silver paste layer and further having a high capacitance per unit volume and a low ESR, and the present invention has been completed.

The organic solvent added to the silver paste forming the laminated structure of the solid electrolytic capacitor absorbs moisture in the air when the silver paste is prepared or when a laminate structure is formed by coating or the like, so that the composition of the silver paste is contained. The amount of water has risen. The ESR of a solid electrolytic capacitor laminated with a silver paste having an increased water content is not sufficiently lowered. The present inventors have carefully studied the results based on these findings and found that in the solid electrolytic capacitor in which the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste layer are sequentially laminated on the surface of the anode substrate composed of the valve action metal. When the water content of the silver paste composition forming the laminate structure is 0.5% by mass or less, particularly 0.3% by mass or less, a solid electrolytic capacitor having a sufficiently low ESR can be provided, and in an environment having a low humidity, The water content of the silver paste composition is 0.5% by mass or less, preferably 0.3% by mass or less, to complete the present invention.

In other words, the present invention relates to a low-ESR high-capacity solid electrolytic capacitor element, a solid electrolytic capacitor including the solid electrolytic capacitor element, and a laminated solid electrolytic capacitor and a layer formed by laminating the solid electrolytic capacitor element. A method of forming a pressure structure, a method of manufacturing a solid electrolytic capacitor element, a solid electrolytic capacitor element produced by the method, and a silver paste forming a laminated structure of a solid electrolytic capacitor.

A solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer and a silver paste layer are sequentially laminated on a surface of an anode substrate composed of a valve action metal, which is coated on the surface of the anode substrate The composition of the silver paste layer on the side (edge) portion of the anode substrate of the oxide film layer, the conductive polymer layer and the carbon paste layer, and the composition or layer thickness of the silver paste layer covering the surface of the anode substrate are controlled.

2. The solid electrolytic capacitor element according to the above 1, wherein the layer thickness of the silver paste layer covering the side (edge) portion of the anode substrate is 6 μm or more, and the layer thickness of the silver paste layer covering the face is 20 μm or less. By.

3. The solid electrolytic capacitor element according to the above 1, wherein the liquid A containing the material for forming the silver paste layer on the anode substrate having the carbon paste layer on the surface is applied to the side (edge) portion of the anode substrate. A liquid B containing a material for forming the silver paste layer and having a higher wettability than the liquid A of the carbon paste layer is applied to the surface of the anode base to form a laminated structure.

4. The solid electrolytic capacitor element according to the above 3, wherein the liquid A is applied to the side (edge) portion of the anode base and dried, and then the anode substrate is immersed in the liquid B to coat the liquid B. A laminate structure is formed by coating the face of the anode substrate.

5. The solid electrolytic capacitor element according to the above 4, wherein only the lower side (edge) portion of the anode base is immersed in the liquid A, whereby the liquid A is applied to the lower side (edge) portion and dried, and then The surface of the anode base was immersed in the liquid B described above, whereby the liquid B was applied to the surface of the anode base to form a laminated structure.

6. The solid electrolytic capacitor element according to the above 3, wherein the liquid B is applied to the surface of the anode substrate and dried, and then the anode substrate is immersed in the liquid A to thereby coat the side of the anode substrate with the liquid A ( The rim portion forms a laminated structure.

7. The solid electrolytic capacitor element according to any one of the above 3 to 6, wherein at least one of the carbon paste layer and the silver paste layer forming the laminated structure is a coating layer containing a fluororesin.

8. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the anode base is in the form of a flat foil, a plate or a rod.

9. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself on the surface portion of the valve action metal.

10. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and alloys based on the metals. Species.

11. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the anode-based system composed of a valve action metal laminated on the surface of the oxide film layer is aluminized to form a foil (formed Al-foil).

A solid electrolytic capacitor comprising the solid electrolytic capacitor element according to any one of the above 1 to 11.

A laminated solid electrolytic capacitor comprising a laminate comprising a plurality of solid electrolytic capacitor elements according to any one of the above 1 to 11 laminated.

14. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste are sequentially laminated on the surface of the anode substrate formed of the valve action metal. In the solid electrolytic capacitor element of the layer, a silver paste layer on the side (edge) portion of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is laminated on the surface of the anode substrate, and the anode is covered. The silver paste layer on the face of the base is thicker.

15. The solid electrolytic capacitor element according to the above 14, wherein the anode base is in the form of a flat foil, a plate or a rod.

16. The solid electrolytic capacitor element according to the above 14, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself of the valve action metal surface portion.

17. The solid electrolytic capacitor element according to the above 14, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium, and alloys based on the metals.

18. The solid electrolytic capacitor element according to the above 14, wherein the anode base body composed of the valve action metal laminated with the oxide film layer on the surface thereof is aluminized to a foil.

19. The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste are sequentially laminated on the surface of the anode substrate composed of the valve action metal. In the solid electrolytic capacitor element of the layer, the thickness of the silver paste layer on the side (edge) portion of the anode substrate on which the oxide film layer, the conductive polymer layer, and the carbon paste layer are laminated on the surface of the anode substrate is 10 μm or more. By.

20. The solid electrolytic capacitor element according to the above 19, wherein the thickness of the silver paste layer on the side (edge) portion of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is sequentially laminated on the surface of the anode substrate. It is 10 to 200 μ m.

21. The solid electrolytic capacitor element according to the above 19, wherein the anode base is in the form of a flat foil, a plate or a rod.

22. The solid electrolytic capacitor element according to the above 19, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself of the valve action metal surface portion.

23. The solid electrolytic capacitor element according to the above 19, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium, and an alloy based on the metal.

24. The solid electrolytic capacitor element according to the above 19, wherein the anode base body composed of the valve action metal laminated with the oxide film layer on the surface thereof is an aluminized foil.

The solid electrolytic capacitor element according to any one of the above 1 to 7, wherein the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste are sequentially laminated on the surface of the anode substrate composed of the valve action metal. In the solid electrolytic capacitor element of the layer, a silver paste constituting a silver paste having a water content of 0.5% by mass or less is laminated.

26. The solid electrolytic capacitor element according to the above 25, wherein the water content is 0.3% by mass or less.

27. The solid electrolytic capacitor element according to the above 25 or 26, wherein the anode base is in the form of a flat foil, a plate or a rod.

The solid electrolytic capacitor element according to any one of the preceding items 25 to 27, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself of the valve action metal surface portion.

The solid electrolytic capacitor element according to any one of the preceding items 25 to 28, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and alloys based on the metals. By.

The solid electrolytic capacitor element according to any one of the above-mentioned items 25 to 29, wherein the anode base body composed of the valve action metal laminated on the surface of the oxide film layer is aluminized into a foil.

A method for forming a laminated structure, which is a method for forming a laminated structure in which a second coating layer is formed on a foil having a first coating layer on the surface thereof, and is characterized in that it comprises a material for forming a second coating layer. a step of applying the liquid A to the side (edge) portion of the foil; and coating the liquid B containing the material for forming the second coating layer and having the wettability of the first coating layer higher than that of the liquid A The step on the face of the foil.

32. The method for forming a laminate structure according to the above 31, wherein the liquid A is applied to a side (edge) portion of the foil and dried, and then the foil is immersed in the liquid B to apply the liquid B. The face of the foil.

33. The method for forming a laminate structure according to the above 32, wherein the lower edge (edge) portion of the foil is immersed in the liquid A and applied to the lower edge (edge) portion, and dried, and then the foil is included. The face is immersed in the liquid B, and the liquid B is applied to the face of the foil.

34. The method for forming a laminate structure according to the above 31, wherein the liquid B is applied to a surface of the foil and dried, and then the foil is immersed in the liquid A to cover the side of the foil with the liquid A. ) Department.

The method of forming a laminated structure according to any one of the above aspects, wherein the at least one of the first coating layer and the second coating layer is a coating layer containing a fluororesin.

The method for forming a laminate structure according to any one of the above aspects, wherein the first coating layer is a carbon paste layer, and the second coating layer is a conductive paste layer other than the carbon paste.

37. A method of manufacturing a solid electrolytic capacitor element, which is a method of manufacturing a solid electrolytic capacitor element in which a carbon paste layer and a conductive paste layer are sequentially formed as a cathode portion on a solid electrolyte layer of a solid electrolytic capacitor element having a solid electrolyte layer on one surface The method is characterized in that the method for forming a laminate structure of the above 36 is used in the lamination step of the carbon paste layer and the conductive paste layer.

38. The method of producing a solid electrolytic capacitor element according to 37 above, wherein the conductive paste is a silver paste.

39. A solid electrolytic capacitor element produced by the method of 38 above.

A solid electrolytic capacitor comprising the solid electrolytic capacitor element of the aforementioned 39.

A laminated solid electrolytic capacitor comprising a laminate comprising a plurality of the solid electrolytic capacitor elements of the foregoing 39 laminated.

42. A method of producing a solid electrolytic capacitor element, comprising: a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on a surface of an anode substrate made of a valve action metal; a manufacturing method characterized by comprising: a step of immersing an anode substrate having an oxide film layer, a conductive polymer layer and a carbon paste layer on a surface of an anode substrate in a silver paste; and a side of the anode substrate The step of coating the silver paste with the bristles.

43. The method of producing a solid electrolytic capacitor element according to the above item 42, wherein the shape of the anode base is a flat foil, a plate or a rod.

The method of producing a solid electrolytic capacitor element according to the above item 42, wherein the dielectric film layer provided on the surface of the anode substrate is provided on an oxide layer of the valve action metal itself in the surface portion of the valve action metal.

The method of producing a solid electrolytic capacitor element according to the above item 42, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium, and an alloy based on the metal.

The method of producing a solid electrolytic capacitor element according to the above item 42, wherein the anode substrate composed of the valve action metal having the oxide film layer laminated thereon is aluminized to a foil.

47. A method of producing a solid electrolytic capacitor element, comprising: a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on a surface of an anode substrate made of a valve action metal; A manufacturing method characterized by laminating a silver paste having a water content of 0.5% by mass or less.

The method of producing a solid electrolytic capacitor element according to the above 47, wherein the water content is 0.3% by mass or less.

The method of manufacturing a solid electrolytic capacitor element according to the above 47 or 48, wherein the shape of the anode base is a flat foil, a plate or a rod.

The method of manufacturing a solid electrolytic capacitor element according to any one of the items 47 to 49, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself of the valve action metal surface portion. .

The method of manufacturing a solid electrolytic capacitor element according to any one of the above items 47 to 50, wherein the valve action metal is a group selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and alloys based on the metals. One of them.

The method of manufacturing a solid electrolytic capacitor element according to any one of the above-mentioned items 47 to 51, wherein the anode base body composed of the valve action metal laminated on the surface of the oxide film layer is aluminized to a foil.

53. A silver paste which is a laminate structure of a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on a surface of an anode substrate made of a valve action metal. It is characterized in that the water content of the silver paste is 0.5% by mass or less.

54. The silver paste according to the above-mentioned item 53, wherein the water content is 0.3% by mass or less.

According to the present invention, it is possible to obtain a solid electrolytic capacitor having a laminated structure in which a silver paste is formed on an anode substrate having a carbon paste layer on its surface, and an ESR (equivalent series resistance) is sufficiently low and a capacitance per unit volume is increased. In the present invention, a solid electrolytic capacitor element having a low ESR and a high capacitance is obtained by controlling the composition or layer thickness of a silver paste having a laminated structure formed on an anode substrate having a carbon paste layer on its surface. When a silver paste having two kinds of compositions having different wettabilities to the carbon paste layer is used and applied to the side (edge) portion and the face portion, the desired layer thickness can be obtained as a whole. When the silver paste having the above two compositions is used, if a component having a low wettability is applied to the edge (edge) portion, and a component having a high wettability is applied to the face, the desired layer thickness can be obtained as a whole. This phenomenon is also widely applied to the formation of a laminated structure of the first covering layer and the second covering layer in order. By controlling the layer thickness of the silver paste forming the laminated structure on the anode substrate having the carbon paste layer on the surface, the silver paste layer covering the side (edge) portion of the anode substrate and the silver covering the face of the anode substrate can be obtained. The layer thickness of the paste layer is controlled by a laminated structure, in particular, the edge portion has a sufficient layer thickness (preferably, a layer thickness of 6 μm or more) and the layer thickness of the face layer is suppressed (the thickness of the layer layer is 20 μm) The following is a solid electrolytic capacitor element having a low ESR (equivalent series resistance) and an increase in capacitance per unit volume. In the method of controlling the thickness of the layer, when the laminated structure of the silver paste is formed on the anode substrate, if the anode substrate is a foil, the method of controlling the layer thickness of the edge portion of the foil and the thickness of the layer on the surface of the foil is particularly effective. Preferably, the silver paste layer covering the side (edge) portion of the anode substrate is thicker than the silver paste layer covering the face portion, and a silver paste constituting the silver paste having a water content of 0.5% by mass or less is preferably used. . Further, the step of immersing the anode substrate on which the oxide film layer, the conductive polymer layer and the carbon paste layer are sequentially laminated on the surface of the anode substrate is immersed in the silver paste; and at the side (edge) portion of the anode substrate The step of applying the silver paste to the bristles can obtain a capacitor having a small thickness unevenness of the silver paste layer and a high capacitance per unit volume and a low ESR. Further, it is preferable to use a silver paste which constitutes the silver paste and has a water content of 0.5% by mass or less. The solid electrolytic capacitor having a sufficiently low ESR and a method for producing the same can be obtained by setting the water content of the silver paste composition forming the laminated structure to 0.5% by mass or less, particularly 0.3% by mass or less. The reason why the ESR of the solid electrolytic capacitor obtained by laminating the silver paste obtained by the composition having a water content of 0.5% by mass or less, particularly 0.3% by mass or less, is not clear, but it can be inferred that when the water content of the laminate is high When the silver paste is formed in a composition of 0.5% by mass, when the solvent of the laminated silver paste is dried, water deteriorates the silver paste layer to increase the ESR. Therefore, according to the present invention, a solid electrolytic capacitor having a sufficiently low ESR and a method of manufacturing the same can be obtained.

Best form for implementing the invention

In the present invention, an anode substrate having a first coating layer (typically a carbon paste layer) on its surface (preferably a foil, the same applies hereinafter) is coated with a material for forming a second coating layer (typically a silver paste layer). In the laminating method of forming the second coating layer by the liquid (hereinafter referred to as the second layer forming liquid), the layer thickness of the side (edge) portion of the second coating layer is extremely small compared with the layer thickness of the face layer. By.

When the second layer forming solution is applied to the first coating layer on the first coating layer, all of the conditions including the surface portion and the edge portion are different in thickness of the layer. These dimensional conditions generally differ depending on the composition of the first coating layer and the second coating layer forming liquid, respectively, but usually include a thickness of 1 mm or less, a width and a length of the surface of 2 or more times, and particularly a thickness of 10 to 500 μ m, the width of the face and the length of 1 mm or more (especially with foil).

The component constituting the first coating layer and the second coating layer is not particularly limited as long as the above phenomenon can occur. However, when at least one of the fluororesin is contained, the thickness of the edge portion is more likely to be the thickness of the layer than the surface layer. Small phenomenon.

For example, the second coating layer is a conductive paste layer (typically a silver paste layer), and when the first coating layer is a carbon paste layer, it corresponds to the above case.

Further, the following description is suitable for the case where the foil used as the anode base body is independently present, but the foil may be fixed to another substrate or the like as long as it can be carried out.

The present invention is characterized in that, in order to form the above-mentioned laminated structure, the method includes the steps of: (1) applying a liquid A containing a composition for forming a material for forming a second coating layer to a side (edge) portion of a foil; And (2) a step of applying a liquid B having a liquid composition having a higher wettability than the liquid A to the surface of the foil as the first coating layer containing the material for forming the second coating layer.

(1) and (2) may be performed first. For example, when (1) is performed first (2), first, the edge containing the foil having the first coating layer on the surface is applied. The liquid A formed by forming the composition of the material of the second coating layer, and then applying the material for forming the second coating layer on both sides of the foil, and the wettability to the first coating layer is higher than that of the liquid A The higher liquid composition is made of liquid B.

The application of the A liquid may be performed on all the side edges of the first coating layer, or may be performed only on either side (edge) portion or even only a part thereof. For example, in the case of a rectangular foil, the step (1) may be performed only on the lower edge (edge). Further, in the present invention, the side (edge) portion refers to a three-dimensional shape such as a foil, a plate or a rod shape in which the shape of the anode base is a flat plate, and the three-dimensional shape is formed by forming a side surface corresponding to the thickness of the anode base body. The side portion and the side portion (edge) when the side portion (edge) portion has a surface portion as a surface relationship, the edge portion of the foil means the edge of the foil (edge) And a surface corresponding to a portion of the thickness between the edges. However, in principle, the area in the vicinity of the parts is also included in the accuracy of the coating method or due to the application of the liquid.

The coating method is not particularly limited. Coating, dipping, printing, spraying of a liquid, projection, and the like, which are performed by using a bristles or a blade, etc. are mentioned. These methods can also be combined. Therefore, for example, after applying the liquid A to the lower edge portion and the side edge portion, the portion containing the surface of the package may be immersed in the liquid B, or only the liquid A may be attached to the lower edge portion. Impregnation, followed by immersion of the portion containing the surface in solution B.

The liquid A and the liquid B have a common point in the composition of the material for forming the second coating layer, but the wettability of the first coating layer is different from the composition of the liquid A in the liquid B. Here, the high wettability means that when an equal amount of the second layer forming liquid adheres to the first layer under the same conditions, it is more likely to diffuse. The adjustment of the wettability can be carried out in various ways depending on the components constituting the first layer and the second layer.

The method for increasing the wettability described above may be, for example, a second layer formed by using a solvent or a component having a higher affinity for the first layer or a second layer. For example, when the first layer is a carbon paste layer and the second layer is a conductive paste layer, in the liquid B, a solvent having a lipophilicity to the carbon paste layer higher than that of the A liquid is used to form a conductive paste layer, or even if it is the same solvent, In the liquid B, the amount of the solvent is larger than that of the liquid A to form a conductive paste layer, or the fluororesin component which is mostly contained in the conductive paste is a composition which is less than the liquid A in the liquid B. However, the adjustment method is not limited. For example, it is effective to add a viscous component to the liquid A to form a liquid of the liquid A, which is lower than the composition of the liquid B.

As described above, in the present invention, the composition or layer thickness of the second layer in the edge portion and the face portion can be independently controlled. As a result, in general, the desired thickness of the layer can be ensured at the edge and the increase in the thickness of the face layer can be suppressed. Therefore, it is suitable for a solid electrolytic capacitor element (Fig. 3) having a thick edge portion of a conductive paste layer and a thin face on an anode substrate having a carbon paste layer on its surface, and a method for producing the same. That is, according to the present invention, the oxide film layer (2), the conductive polymer layer (3), the carbon paste layer (4a), and the silver paste are sequentially laminated on the surface of the anode substrate (1) composed of the valve action metal. In the solid electrolytic capacitor element of the layer (4b), the oxide film layer (2), the conductive polymer layer (3), and the carbon paste layer (4a) are laminated in this order by controlling the surface of the anode substrate (1). A low ESR (Equivalent Series Resistance) and a unit per unit can be obtained by the composition or layer thickness of the silver paste layer (4b) at the edge (edge) portion of the anode substrate and the silver paste layer (4b) covering the surface of the anode substrate. Solid electrolytic capacitor element with increased capacitance of volume. According to the present invention, it is possible to obtain a low ESR (equivalent series resistance) in which the silver paste layer (4b) covering the edge (edge) portion of the anode substrate has a sufficient layer thickness and the layer thickness of the silver paste layer (4b) covering the face is suppressed. And a solid electrolytic capacitor element having an increased capacitance per unit volume. Applying the liquid A containing the composition of the material for forming the silver paste layer (4b) on the anode substrate having the carbon paste layer (4a) on the surface thereof is applied to the side (edge) portion of the anode substrate to contain silver. The liquid B for the paste layer (4b) and the liquid B made of the liquid paste layer (4a) having a higher wettability than the liquid composition of the liquid A are applied to the face of the anode substrate to form a solid of the desired laminated structure. Electrolytic capacitor components are preferred. After applying the liquid A to the side of the anode substrate (edge) and drying it, the anode substrate is immersed in the liquid B, whereby the liquid B is applied to the surface of the anode substrate to form a desired laminated structure. Solid electrolytic capacitor component. Alternatively, the lower side (edge) portion of the anode substrate may be immersed in the liquid A and applied to the lower edge (edge) portion, and dried, and then the surface including the anode substrate may be immersed in the liquid B, and the liquid B may be applied to the anode. The surface of the substrate may also form a solid electrolytic capacitor element having a desired laminated structure. After the B liquid is applied to the surface of the anode substrate and dried, the anode substrate is immersed in the A liquid, and the anode substrate is coated with the A liquid. The side (edge) portion can also form a solid electrolytic capacitor element having a desired laminated structure. Even in the case where at least one of the carbon paste layer (4a) and the silver paste layer (4b) is a coating layer containing a fluororesin, a silver paste layer (4b) covering the side (edge) portion of the anode substrate can be obtained. A solid electrolytic capacitor element having a low ESR (equivalent series resistance) in which the layer thickness of the silver paste layer (4b) having a sufficient layer thickness and covering the face is suppressed and the capacitance per unit volume is increased. The present invention provides such a low-ESR high-capacitance solid electrolytic capacitor element, a solid electrolytic capacitor including the solid electrolytic capacitor element, and a laminated solid electrolytic capacitor in which a plurality of the above-described solid electrolytic capacitor elements are laminated.

As shown in Fig. 3, the solid electrolytic capacitor element is formed of an oxide film layer (2) of a dielectric material formed on the anode base (1), and a solid semiconductor layer (hereinafter referred to as a solid electrolyte) as a counter electrode is formed on the outer side. (3) A solid electrolytic capacitor element in which a conductor layer (4) such as a conductive paste is formed, and the conductor layer (4) has a two-layer structure, and typically includes a carbon paste layer (4a) and a side (edge) portion. The desired thickness of the layer and the increase in the thickness of the face layer are suppressed by the conductive paste layer (4b).

The solid electrolytic capacitor of the present invention and the method for producing the same are characterized in that an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on the surface of an anode substrate made of a valve action metal.

An anode substrate having an oxide film layer laminated thereon and comprising a valve action metal, and coating all of the silver paste on the carbon paste layer laminated on the conductive polymer layer of the anode substrate The edge (edge) portion may have a dimensional condition of different layer thicknesses, and the "edge (edge)" refers to the side edge (edge) opposite to the anode and the side edge orthogonal to the edge (edge) ( 3 sides (edges) of the edge. The composition of the carbon paste layer and the silver paste layer is not particularly limited.

The present invention relates to a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on a surface of an anode substrate composed of a valve action metal, and a method for producing the same, and is used for forming The silver paste layer of the above laminated structure has characteristics. That is, the present invention is to control the silver paste layer of the anode substrate edge portion of the oxide film layer, the conductive polymer layer, and the carbon paste layer, which is laminated on the surface of the anode substrate, and to cover the anode substrate. a solid electrolytic capacitor element having a low ESR (equivalent series resistance) and a capacitance per unit volume increased in composition or layer thickness of the silver paste layer of the face, in a specific aspect of the invention, covering the side of the anode substrate Preferably, the silver paste layer is thicker than the silver paste layer covering the surface of the anode substrate, or the silver paste layer covering the side of the anode substrate has a thickness of 10 μm or more. A preferred thickness is about 10 to 200 μm. A specific aspect of the present invention is characterized in that the capacitor is manufactured by the method of: immersing an anode substrate of an oxide film layer, a conductive polymer layer, and a carbon paste layer on a surface of an anode substrate in a step of immersing in a silver paste. And a step of coating the silver paste with bristles on the side of the anode substrate.

A method for forming a silver paste layer on a surface of an anode substrate formed by sequentially laminating an oxide film layer, a conductive polymer layer, and a carbon paste layer on the surface of an anode substrate is a method for forming a silver paste layer which is generally known per se. For example, a dipping method in which the silver paste is immersed in a storage tank and then pulled up, a method in which the bristles containing the paste are applied to the surface thereof, and a method in which the paste is sprayed on the surface thereof by spraying is applied. The method, the method in which the roller to which the adhesive is attached is pressed against the surface to be coated, and the screen printing method in which the paste is dropped on the surface by a mesh.

A method of forming a silver paste layer on the side of an anode substrate of an oxide film layer, a conductive polymer layer, and a carbon paste layer, which is laminated on the surface of the anode substrate, as long as a method for forming a paste layer which is generally known per se is used. The method for forming the covering edge is appropriately selected, and the method for forming the adhesive layer for covering the edge is exemplified by a dipping method in which the silver paste in the storage tank is immersed and pulled up, and the paste is contained. The method in which the bristles are applied to the side of the bristles, and the method in which the bristles are sprayed on the side by spraying, and the like.

As described above, the method of forming the silver paste layer on the surface or the side (edge) portion of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is sequentially laminated on the surface of the anode substrate, as long as the cost is up to the invention. The purpose is not particularly limited. That is, the method for forming the silver paste layer may be, for example, coating, dipping, printing, liquid spraying, projection, or the like by brushing or spraying. These methods can also be combined. Therefore, for example, after coating the lower edge portion and the side edge portion by the brush coating method, the portion including the surface may be impregnated, or only the lower edge portion may be immersed, and then the portion including the surface may be impregnated, thereby producing the silver of the covering edge. The paste layer is thicker than the silver paste layer of the cover layer, or the solid electrolytic capacitor of the present invention having a thickness of the silver paste layer covering the edge of 10 μm or more.

a step of immersing an anode substrate in which an oxide film layer, a conductive polymer layer, and a carbon paste layer are sequentially laminated on a surface of an anode substrate in a silver paste; and a capacitor for coating a silver paste with a brush on the side of the anode substrate In the manufacturing method, since the step of applying the silver paste to the portion or the whole including the surface of the surface by the dipping method and the step of applying the silver paste to the side with the bristles may be carried out in combination, the thickness of the silver paste layer is less uneven. Capacitors with high capacitance per unit volume and low ESR can be fabricated.

In the present invention, after the conductive polymer layer is laminated on the oxide film layer on the surface of the anode substrate made of the valve action metal, the carbon paste layer and the silver paste layer are sequentially laminated. After the formation of the conductive polymer layer, the anode substrate recrystallized as desired is immersed in the carbon paste, whereby the carbon paste can be applied to the surface thereof and dried to laminate the carbon paste layer. The carbon paste to be used is generally composed of a solvent such as carbon particles, a fluororesin, and isoamyl acetate.

The anode substrate in which the carbon paste layer is sequentially laminated is immersed in the silver paste, whereby the silver paste can be applied to the surface thereof. The silver paste used is generally composed of a solvent such as silver particles, a fluororesin, and isoamyl acetate. The shape of the coated silver particles is not particularly limited, but a flake is preferred.

The step of the present invention has a step of immersing an anode substrate having an oxide film layer, a conductive polymer layer and a carbon paste layer on the surface of the anode substrate in a step of impregnating the silver paste (impregnation step) on the side of the anode substrate. The step of applying the silver paste to the bristles (bristle coating step) may be performed first by any of the impregnation step and the bristle coating step. For example, as described above, after the impregnation step of immersing the anode substrate in the silver paste, a brush coating step of coating the silver paste with the bristles is performed on the side of the anode substrate. The bristles to be used are not particularly limited, but a pen is preferred, and for example, a commercially available stylus can be used. The thickness of the silver paste layer in the inner side (inside) of the anode substrate obtained by drying is 10 μm or more, particularly preferably 10 to 200 μm.

As described above, after laminating two anode substrates in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are laminated, for example, on a lead frame, an oxide film layer is not formed and is electrically conductive. The portions of the polymer layer, the carbon paste layer, and the silver paste layer are welded to the lead frame, and the laminated anode substrate is encapsulated with an epoxy resin, thereby manufacturing a wafer of a solid electrolytic capacitor.

The solid electrolytic capacitor of the present invention will be described in detail below.

(valve action metal)

In the solid electrolytic capacitor of the present invention and the method for producing the same, the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste layer are sequentially laminated on the surface of the anode substrate composed of the valve action metal. In the present invention, as the valve action metal used for the anode base of the solid electrolytic capacitor, for example, any of aluminum, tantalum, titanium, niobium, zirconium, and an alloy based on the metal may be used. The shape of the anode base body may be, for example, a flat foil or a plate or a rod shape. An anode substrate having an oxide film layer laminated on its surface and composed of a valve action metal is provided on the surface of the carbon paste layer laminated on the conductive polymer layer laminated thereon In the case of a size condition in which the thickness of the layer is different from the edge (edge) portion, since the aluminized foil is economically excellent, it is widely used in practice. The aluminized foil is a rectangle having a thickness of 40 to 200 μm and a width of about 1 to 30 mm in terms of a flat element unit. It is preferably 2 to 20 mm in width and 2 to 20 mm in length, more preferably 2 to 5 mm in width and 2 to 6 mm in length.

The dielectric film layer disposed on the surface of the anode substrate may be an oxide layer of the valve action metal itself disposed on the surface of the valve action metal, or may be other layers disposed on the surface of the valve action metal or the valve action metal foil. The electric layer is preferably a layer composed of an oxide of the valve action metal itself.

A portion of the end portion of the flat anode substrate on which the dielectric film layer is formed on the surface may be used as the anode portion, and the remaining portion may serve as the cathode portion. An insulating resin tape (masking) can be used to distinguish the anode portion from the cathode portion.

(solid electrolyte)

Then, a solid electrolyte is formed on the dielectric film layer of the cathode portion. However, the type of the solid electrolyte layer is not particularly limited, and a conventionally known solid electrolyte can be used, but a conductive polymer having a particularly high conductivity is used as the solid electrolyte. Compared with a solid electrolytic capacitor using a known electrolytic capacitor or a solid electrolytic capacitor using manganese dioxide, the solid electrolytic capacitor produced has a low equivalent series resistance component, a large capacitance and a small size, and high frequency performance. Good, so it is ideal.

The conductive polymer forming the solid electrolyte used in the solid electrolytic capacitor of the present invention is not limited, and preferably, for example, a conductive polymer having a π-electron conjugated structure, for example, a compound having a thiophene skeleton, A conductive polymer having a structure of a polycyclic sulfide skeleton, a compound having a pyrrole skeleton, a compound having a furan skeleton, or the like as a repeating unit.

Among the monomers used as a raw material of the conductive polymer, the compound having a thiophene skeleton may, for example, be 3-methylthiophene, 3-ethylthiophene, 3-propylthiophene, 3-butylthiophene or 3-pentyl Thiophene, 3-hexylthiophene, 3-heptylthiophene, 3-octylthiophene, 3-mercaptothiophene, 3-mercaptothiophene, 3-fluorothiophene, 3-chlorothiophene, 3-bromothiophene, 3-cyano Derivatives such as thiophene, 3,4-dimethylthiophene, 3,4-diethylthiophene, 3,4-butylthiophene, 3,4-methyldioxythiophene, 3,4-ethylenedioxythiophene Things. Such compounds can generally be prepared using commercially available compounds or by well-known methods (e.g., Synthetic Metals, 1986, Vol. 15, p. 169).

Further, for example, a compound having a polycyclic sulfide skeleton can be, for example, a compound having a skeleton of 1,3-dihydropolycyclic sulfide (alias: 1,3-dihydrobenzo[c]thiophene), having 1 a compound of the 3-dihydronaphtho[2,3-c]thiophene skeleton. Further, a compound having a 1,3-dihydroindolo[2,3-c]thiophene skeleton and a compound having a 1,3-dihydrofused tetrabenzo[2,3-c]thiophene skeleton may be mentioned. It is prepared by a method known in the art, for example, in the method described in JP-A-8-3156.

Further, for example, a compound having a 1,3-dihydronaphtho[1,2-c]thiophene skeleton, a 1,3-dihydrophenanthro[2,3-c]thiophene derivative, and a 1,3-dihydrogen thick a compound of a tribenzo[2,3-c]thiophene skeleton, a 1,3-dihydrobenzo[a]indolo[7,8-c]thiophene derivative or the like.

There are also compounds containing nitrogen or an N-oxide in the fused ring, and examples thereof include: 1,3-dihydrothieno[3,4-b]quinoline Porphyrin, 1,3-dihydrothieno[3,4-b]quinoline Porphyrin-4-oxide, 1,3-dihydrothieno[3,4-b]quin Porphyrin-4,9-dioxide or the like, but is not limited thereto.

Further, examples of the compound having a pyrrole skeleton include 3-methylpyrrole, 3-ethylpyrrole, 3-propylpyrrole, 3-butylpyrrole, 3-pentylpyrrole, 3-hexylpyrrole, and 3-heptyl group. Pyrrole, 3-octylpyrrole, 3-mercaptopyrrole, 3-mercaptopyrrole, 3-fluoropyrrole, 3-chloropyrrole, 3-bromopyrrole, 3-cyanopyrrole, 3,4-dimethylpyrrole, Derivatives such as 3,4-diethylpyrrole, 3,4-butylpyrrole, 3,4-methyldioxypyrrole, and 3,4-ethanedioxypyrrole are not limited thereto. These compounds can be prepared commercially or by known methods.

Further, examples of the compound having a furan skeleton include 3-methylfuran, 3-ethylfuran, 3-propylfuran, 3-butylfuran, 3-pentylfuran, 3-hexylfuran, and 3-heptyl group. Furan, 3-octylfuran, 3-mercaptofuran, 3-mercaptofuran, 3-fluorofuran, 3-chlorofuran, 3-bromofuran, 3-cyanofuran, 3,4-dimethylfuran, Derivatives such as 3,4-diethylfuran, 3,4-butanefuran, 3,4-methyldioxyfuran, and 3,4-ethanedioxyfuran are not limited thereto. These compounds can be prepared commercially or by known methods.

The polymerization process can be electrolytic polymerization or chemical oxidative polymerization or a combination of these. Further, a method in which a solid electrolyte other than a conductive polymer is formed on the dielectric film and then a conductive polymer is formed by the above polymerization method may be employed.

The method of forming a conductive polymer may be a method in which a 3,4-ethylenedioxythiophene monomer and an oxidizing agent are preferably applied to a dielectric film separately or in a solution state in a solution state (Japanese Patent Application) Kaikai No. 2-15611 or Japanese Patent Laid-Open No. Hei 10-32145).

In general, the conductive polymer uses a compound having a doping energy (dopant), and the dopant may be added to either the monomer solution or the oxidant solution, or may be a dopant and The oxidizing agent is an organic sulfonic acid metal salt of the same compound or the like. As the dopant, an aryl sulfonate-based dopant is preferably used. For example, a salt of benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, sulfonic acid, sulfonic acid or the like can be used.

The solid electrolyte produced as described above has an electrical conductivity in the range of from about 0.1 to about 200 S/cm, preferably from about 1 to about 150 S/cm, more preferably from about 10 to about 100 S/cm.

(carbon paste layer)

In the present invention, after the conductive polymer layer is laminated on the oxide film layer on the surface of the anode substrate made of the valve action metal, the carbon paste layer is laminated. The carbon paste to be used is generally composed of a solvent such as carbon particles, a fluororesin, and isoamyl acetate. The component constituting the carbon paste layer is not particularly limited. After the formation of the conductive polymer layer, the carbon paste is immersed in the above-described composition, for example, by immersing it in the carbon paste of the above composition, and the carbon paste is applied to the surface thereof to dry and laminate the carbon paste layer.

The oxide film layer and the conductive polymer layer are sequentially laminated on the surface of the anode substrate, and then the carbon paste layer is laminated. The method for forming the carbon paste layer may be a conventionally known method for forming a paste layer, such as a dipping method. Brush coating method, spray method, roller method, screen printing method, and the like. In other words, a method of forming a carbon paste layer by laminating a conductive polymer layer on an anode substrate having an oxide film layer is performed by subjecting an oxide film layer to form an anode of a conductive polymer layer thereon. a method in which a substrate is immersed in a carbon paste and then immersed, a method in which a bristles containing a carbon paste are applied in contact with the anode substrate, a method in which a carbon paste is sprayed onto the anode substrate by spraying, and a method in which carbon is adhered A method in which the paste roller presses and rotates the anode substrate, and a screen printing method in which a carbon paste is dropped from the mesh hole on the anode substrate.

(silver paste layer)

After laminating the carbon paste layer, the silver paste layer is then laminated. In a preferred embodiment of the present invention, the silver paste forming the laminate structure is composed of a solvent such as silver particles, a fluororesin, and isoamyl acetate, and 0.5% by mass or less, preferably 0.3% by mass or less. Composition. The shape of the coated silver particles is not particularly limited, but is preferably a sheet shape. The invention is characterized by forming a silver paste in a laminated construction. That is, the solid electrolytic capacitor of the present invention is characterized in that the water content of the silver paste laminated by laminating the anode substrate with the oxide film layer, the conductive polymer layer and the carbon paste layer on the surface of the anode substrate is It is preferably 0.5% by mass or less, particularly preferably 0.3% by mass or less. The water content of the silver paste of the composition may be 0.5% by mass or less, preferably 0.3% by mass or less, more preferably 0.05% by mass or less, and most preferably 0.02% by mass to 0.3% by mass.

The silver paste of the present invention is usually composed of a solvent such as silver particles, a fluororesin, and isoamyl acetate, and can be prepared by mixing the constituent components. The mixing ratio of the constituent components used for the preparation of the silver paste is generally 45 to 65 mass% of the silver particles, 1 to 10 mass% of the fluororesin, and acetic acid equivalent for the entire silver paste composed of the silver paste. The solvent such as amyl ester is 30 to 50% by mass. The solvent to be added to the silver paste is generally an organic solvent. When the organic solvent is used to prepare a silver paste or when a laminate structure is formed by coating or the like, moisture in the air is absorbed, and the water content of the silver paste is formed. rise. Therefore, the ESR of the solid electrolytic capacitor obtained by laminating the silver paste having a composition having an increased water content is not sufficiently lowered. Therefore, the organic solvent to be used is preferably one which is initially composed of a water content of 0.5% by mass or less. When it is necessary to dehydrate the organic solvent, for example, it can be dehydrated by a method using a dehydrating agent such as zeolite or a method of permeable to water and a polymer film which is difficult to permeate the organic solvent. By such a method, the water content in the organic solvent can be lowered to prepare a silver paste having a composition of water content of 0.5% by mass or less, preferably 0.3% by mass or less.

The silver paste having a composition having a water content of 0.5% by mass, preferably 0.3% by mass or less, is preferably stored at a humidity of 30 to 60%, preferably 30 to 50% by humidity, more preferably 30 to 40% by humidity. %, or a closed container adjusted to such humidity, preferably in a desiccator, or coexisting with a desiccant such as silicone. The temperature at this time is preferably 15 to 30 ° C, more preferably 21 to 27 ° C, more preferably 23 to 25 ° C, and the following temperatures may be selected. When the silver paste of the above composition is prepared or when a laminate structure is formed by coating or the like, the humidity is preferably 30 to 60%, the humidity is preferably 30 to 50%, the humidity is preferably 30 to 40%, or the following is selected. The humidity can also be. The temperature at this time is preferably 15 to 30 ° C, more preferably 21 to 27 ° C, and even more preferably 23 to 25 ° C. The temperature below may be selected. When the humidity is 70% or more, even in the environment of a temperature of 15 to 30 ° C, when the silver paste of the above composition is used for 48 hours or more, the water content of the composition silver paste increases and exceeds 0.5%, and there is a case where The case of the ESR reducing effect of the present invention cannot be obtained.

The silver paste of the above composition of the present invention is laminated by lamination to form a laminated structure, but the silver paste layer covering the side of the anode substrate is preferably thicker than the silver paste layer covering the surface of the anode substrate. The thickness of the silver paste layer covering the side of the anode substrate is preferably 10 μm or more, particularly preferably about 10 to 200 μm. Further, in the method for producing a solid electrolytic capacitor of the present invention, preferably, an anode substrate having an oxide film layer, a conductive polymer layer, and a carbon paste layer laminated on the surface of the anode substrate is immersed in the silver of the above composition. a step of pasting; and a step of coating the silver paste with bristles on the side of the anode substrate.

In the solid electrolytic capacitor in which the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste layer of the above composition are sequentially laminated on the surface of the anode substrate composed of the valve action metal, the silver covering the side of the anode substrate When the paste layer is thicker than the silver paste layer of the cover surface or the thickness of the silver paste layer covering the side of the anode substrate is 10 μm or more, the edge portion can have a sufficient layer thickness and the thickness of the face layer can be suppressed. A solid electrolytic capacitor element having a low ESR (equivalent series resistance) and an increase in capacitance per unit volume is preferable.

In the method for producing a solid electrolytic capacitor in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer of the above composition are sequentially laminated on a surface of an anode substrate composed of a valve action metal, the anode base body is to be used. a step of immersing an anode substrate having an oxidized coating layer, a conductive polymer layer, and a carbon paste layer on the silver paste of the above composition in sequence; and manufacturing the step of coating the silver paste with bristles on the side of the anode substrate In the method, the step of coating the silver paste by a dipping method and the step of coating the silver paste with a bristles by a portion or a whole of the surface thereof, the thickness of the silver paste layer is small, and thus the film can be manufactured. It is preferable to have a solid electrolytic capacitor having a high capacitance per unit volume and a low ESR.

a step of immersing an anode substrate having an oxide film layer, a conductive polymer layer, and a carbon paste layer on the surface of the anode substrate composed of a valve action metal in a silver paste of the above composition (impregnation step), and the anode The step of coating the silver paste with the bristles on the side of the substrate (bristle coating step) may be performed first by either of the immersing step and the bristles coating step. For example, after the anode substrate is immersed in the impregnation step of the silver paste, a bristle coating step of coating the silver paste with the bristles is performed on the side of the anode substrate. The bristles to be used are not particularly limited, but a pen is preferred, and for example, a commercially available stylus can be used. The thickness of the silver paste layer in the inner side (inside) of the anode substrate obtained by drying is 10 μm or more, particularly preferably 10 to 200 μm.

The method for forming the silver paste layer having the above-described composition in which the surface of the anode substrate is laminated on the surface of the anode substrate, and the surface of the anode layer of the carbon paste layer is laminated, for example, the silver immersed in the storage tank a dipping method in which the paste is pulled up, a brush coating method in which the bristles containing the silver paste are applied to the surface thereof, a spray method in which the silver paste is sprayed on the surface thereof by spraying, and a coating method is applied. A drum method in which the drum of the silver paste is pressed against the surface and rotated, and a screen printing method in which the silver paste is dropped by a sieve hole on the surface thereof.

A method for forming a silver paste layer having the above-described composition in which an oxide film layer, a conductive polymer layer, and an anode base of a carbon paste layer are laminated on the surface of an anode substrate, and is suitably formed by the method for forming the silver paste layer The method for forming the covering edge may be selected, and the method for forming the silver paste layer suitable for the covering edge may be, for example, a dipping method in which the silver paste is immersed in a storage tank, and a bristles containing the silver paste. A method of applying a brush to be applied while contacting the side, and a spraying method of applying the silver paste to the side by spraying, and the like.

As described above, the method for forming a silver paste layer having the above-described composition of the surface portion and/or the edge portion of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is laminated on the surface of the anode substrate. It is not particularly specific as long as it can achieve the purpose of the invention, and the silver paste forming method may be, for example, coating, dipping, printing, liquid spraying, projection, or the like by bristles or spray, or combining the methods. It suffices to appropriately select a suitable formation method in each of these methods. Therefore, for example, after coating the lower edge portion and the side edge portion by the brush coating method, the portion including the surface may be immersed, or only the lower edge portion may be immersed, and then the portion including the surface may be immersed. Thereby, a thick solid electrolytic capacitor having a thickness of the above-mentioned silver paste layer covering the edge of the silver paste layer or covering the side of the silver paste layer having a thickness of 10 μm or more can be produced.

(solid electrolytic capacitor)

The solid electrolytic capacitor element thus obtained is usually connected to a lead terminal, and is molded into a capacitor product of various uses by, for example, resin molding, a resin outer casing, a metal outer casing, resin impregnation, or the like. In addition, laminate packaging is also possible. That is, for example, 2 to 4 anode substrates of an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on the surface of the anode substrate composed of a valve action metal, and laminated, for example, to After the lead frame, a portion where the oxide film layer, the conductive polymer layer, the carbon paste layer, and the silver paste layer are not formed is soldered to the lead frame, and the lead terminals are connected, and by, for example, resin molding, The resin outer casing, the metal outer casing, the epoxy resin impregnation, and the like can be used to form a laminated solid electrolytic capacitor product for various purposes.

[Examples]

Representative examples of the invention are shown below and are further described in detail. These are for illustrative purposes only and are not intended to be limiting.

In the following examples, the equivalent series resistance (ESR) was measured at 100 kHz using an LCR tester 4284A manufactured by Hewlett-Packard.

(Example 1)

On aluminized foil (hereinafter referred to as a chemical conversion foil) having a short axis direction of 3 mm × a long axis direction of 10 mm and a thickness of about 100 μm, a masking material (heat resistant resin) was used to form a circumferential width of 1 mm, and was divided into cathodes. In the portion and the anode portion, the cathode portion of the partition portion on the end side before the formation of the foil is energized in the electrolytic solution, and is formed into a water wash. Next, the cathode portion was immersed in an isopropanol solution of 3,4-ethylenedioxythiophene at 1 mol/L, followed by immersion in a mixture of an oxidizing agent (ammonium persulfate) and a dopant (sodium naphthalene-2-sulfonate). In an aqueous solution, oxidative polymerization is carried out. The impregnation step and the polymerization step are repeated to form a dopant-containing solid electrolyte layer in the fine pores of the chemical conversion foil. The chemical conversion foil in which the solid electrolyte layer containing the dopant was formed was washed with water to form a solid electrolyte layer and dried by hot air. A carbon paste is coated thereon to form a component material.

On the other hand, 85 mass% of the silver powder was mixed with 15 mass% of VITON rubber (fluorine-based rubber composed of a vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer) powder to form a solid component constituting the conductive paste. The isoamyl acetate as a solvent was added thereto, and kneaded to prepare a viscous silver paste having a composition of 70% by mass of solid content (solution A: hereinafter referred to as "first composition"). In addition, a silver paste of another composition (B liquid: hereinafter referred to as "second composition") was prepared in the same manner as the liquid A except that the solid content was changed to a composition of 60% by mass. The silver paste of the first composition and the second composition was dropped on the carbon paste layer of the element material, and the wettability was confirmed. As a result, it was confirmed that the wettability of the first composition was lower than the wettability of the second composition.

The element material attached to the support member so as to have the cathode side downward is prepared, and the silver paste groove containing the silver paste (liquid A) of the first composition is placed, and the support member is lowered to make the cathode side of the element material The front end of 0.5 mm (only the lower edge) was immersed in the aforementioned silver paste. Next, the support member is raised to pull the component material from the liquid and dried by warm air. Next, the support member was lowered, and 3.3 mm of the cathode side of the element material was immersed in the silver paste (liquid B) formed by the above second composition. Then, the support member is raised to draw the component material from the liquid and dried.

(Example 2)

In the same manner as in the first embodiment, the element material attached to the support member is provided so that the cathode side is downward, and the silver paste (liquid A: first composition) is applied to the cathode edge portion (the entire edge). After drying, the silver paste was placed in a silver paste containing a silver paste (solution B: second composition), and the support member was lowered to immerse the front end of the element material at a side of 3.3 mm in the silver paste. Next, the support member is raised to pull the component material from the liquid and dry it.

(Example 3)

In the same manner as in the first embodiment, the element material attached to the support member was prepared so that the cathode side was below, and the silver paste (liquid B: second composition) was applied to the cathode surface, dried, and then contained. The silver paste of the silver paste (liquid A: first composition) was lowered to lower the support member so that the front end of the cathode side of the element material was 0.5 mm (only the lower edge) was immersed in the silver paste. Next, the support member is raised to pull the component material from the liquid and dry it.

(Comparative Example 1)

In Example 1, except that the silver paste of the first composition was used instead of the second composition, the same treatment was carried out to form a silver paste layer.

(Comparative Example 2)

In Example 1, except that the silver paste of the second composition was used instead of the silver paste of the first composition, the same treatment was carried out to form a silver paste layer.

The capacitor element produced in each of the above Examples and Comparative Examples was cut away from the supporting member, and the thickness of the silver paste layer was observed with a microscope. The results are shown in Table 1.

Further, 4 pieces of the capacitor element of Example 1 were laminated on a lead frame, and 50 solid electrolytic capacitors each having a rated capacity of 220 μF and a rated voltage of 2 V were obtained. Similarly, in the capacitor element obtained in the comparative example, four sheets were laminated on the lead frame to obtain 50 solid electrolytic capacitors each having a rated capacity of 220 μF and a rated voltage of 2 V. Each of the 50 solid electrolytic capacitors thus obtained was welded to the substrate using a reflow oven at 250 ° C, and the equivalent series resistance (ESR) was measured. The results are shown in Table 1. In the case where the ESR is 9 mΩ or less, the value is ○ mark (more than 8 mΩ and 9 mΩ or less), and the particularly good value is ◎ (8 mΩ or less). In addition, those whose ESR exceeds the qualified value are set as the unacceptable value and are marked with × (greater than 9 mΩ). Further, the laminate thickness is a thickness of the element laminate in which four capacitor elements are laminated on the lead frame.

However, the pattern formed by the silver paste layer of each of the examples in Table 1 is as follows.

Example 1: Low wettability (lower edge only) + high wettability Example 2: low wettability (total) + high wettability Example 3: high wettability + low wettability (only Lower edge) Comparative Example 1: Low wettability (lower edge only) + low wettability Comparative Example 2: High wettability (lower edge only) + high wettability

As shown in Comparative Example 1, when a silver paste having low wettability was applied to the face portion and the lower edge portion, the laminate thickness was large. Therefore, it is impossible to manufacture a capacitor having an increased capacitance per unit volume. On the other hand, as shown in Comparative Example 2, when the silver paste having high wettability was applied to the face portion and the lower edge portion, the ESR of the capacitor was high. Therefore, as shown in the first embodiment, by applying a silver paste having a low wettability to the lower edge portion and applying a silver paste having a high wettability to the face, the laminate thickness is small, and therefore, each of the laminates can be manufactured. A capacitor with a large capacitance per unit volume and a low ESR.

As shown in the above examples, according to the manufacturing method of the present invention, electrical characteristics, particularly ESR, are improved, and laminate thickness is also remarkably improved. That is, according to the present invention, as shown in the above example, when the laminated structure of the silver paste is formed on the anode substrate, low ESR (equivalent series resistance) can be obtained by controlling the layer thickness of the edge portion and the layer thickness of the face portion. And a solid electrolytic capacitor element in which the capacitance per unit volume is increased. In particular, a capacitor element in which the ESR (equivalent series resistance) is stabilized and reduced and the thickness of the element is small can be manufactured. When two kinds of silver pastes having different wettability to the carbon paste layer are used, if a component having a low wettability is applied to the edge (edge) portion, a component having a high wettability is applied to the face, that is, The desired layer thickness is obtained overall.

(Example 4)

First, the aluminum foil having an increased surface area by etching is cut into an elongated shape of 3 mm × 10 mm, and the lower half of the elongated aluminum foil and the electrode are immersed in an aqueous solution of ammonium adipate having a temperature of 80 ° C and a concentration of 10%. A voltage of 3 V was applied for 10 minutes to flow a current therebetween, thereby forming an aluminum foil, and a film of a derivative of alumina was formed on the surface of the lower half of the foil.

Then, the aluminum foil obtained by immersing it in an isopropyl alcohol solution in which 3,4-ethylenedioxythiophene is dissolved is dried, and after being immersed in an aqueous solution containing sodium sulfonate and ammonium persulfate, In the drying step, the conductive polymer layer of the poly 3,4-ethylenedioxythiophene is attached to the dielectric film by repeating the above steps.

Further, the foil and the electrode on which the conductive polymer layer was formed were immersed in an aqueous solution of ammonium adipate having a temperature of 80 ° C and a concentration of 10%, and a dielectric voltage of 3 V was applied for 1 minute to re-form the dielectric film. The re-formed aluminum foil is immersed in a carbon paste composed of carbon particles having a weight ratio of 7%, a fluororesin having a weight ratio of 3%, and isoamyl acetate having a weight ratio of 90%, thereby being used for the aluminum foil. The surface is coated with carbon paste. The viscosity of the carbon paste is 60 cpoise. The coated carbon particles were composed of particles having a particle diameter of 10 to 100 nm and particles having a particle diameter of 0.8 to 8 μm, and the weight ratio was 30:70. After drying at a temperature of 130 ° C for 10 minutes, the thickness of the carbon paste layer was 5 μm, and the weight ratio of carbon particles contained in the carbon paste layer was 70%.

Next, the carbon paste-coated aluminum foil was immersed in a silver paste composed of silver particles having a weight ratio of 54%, a fluororesin having a weight ratio of 6%, and isoamyl acetate having a weight ratio of 40%. This is coated with a silver paste on the surface of the aluminum foil. The viscosity of the silver paste is 400 cpoise. The coated silver particles have a sheet shape and have a length in the long axis direction of 1 to 5 μm. After drying at a temperature of 130 ° C for 10 minutes, the thickness of the silver paste layer was 15 μm, and the weight ratio of the silver particles contained in the silver paste layer was 90%.

The silver paste applied by the dipping method was applied to the side of the aluminum foil coated with the silver paste by dipping, and then dried at a temperature of 130 ° C for 10 minutes.

The bristles are coated with a commercially available paint pen (with a length of about 2 cm) of the water-based paint, and the stylus is immersed in the silver paste, and the silver paste contained in the paint pen is completely removed by the wall of the container. The pen tip is gently touched by the edge of the foil from the upper side to make the pen move parallel to the side, and a small amount of silver paste is applied near the side (within 1 mm from the side).

The aluminum foil to which the silver paste was applied was embedded in a two-liquid mixed-hardening resin, and the resin was cut at intervals of 1 mm after hardening, and the cross section of the aluminum foil was observed under an optical microscope to measure the thickness distribution of the silver paste layer in the surface of the aluminum foil. As a result, the thickness of the silver paste layer was mostly 15 μm. Further, the thickness of the silver paste layer in the side of the aluminum foil was measured and found to be 23 to 38 μm.

After laminating two aluminum foils in which an aluminum oxide layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are laminated on a lead frame, an aluminum oxide layer and a conductive polymer layer are not formed. The portions of the carbon paste layer and the silver paste layer are welded to the lead frame, and the laminated aluminum foil is encapsulated with epoxy resin, thereby manufacturing a wafer of the capacitor.

The results of the capacitors evaluated by the LCR tester were 102.6 μF for the 120 Hz capacitor and 7.4 mΩ for the ESR at 100 kHz. Further, as a result of measuring a leakage current by applying 2 V to 100 capacitors, there were 100 capacitors having a leakage current of 5 μA or less.

(Example 5)

In the same manner as in Example 4, the silver paste coated by the dipping method was applied to the side of the aluminum foil coated with the silver paste by a dipping method, and then dried at a temperature of 130 ° C for 10 minutes. The coating by the dispenser is such that the front end of the dispenser contacts the edge of the foil and moves it parallel to the side at a constant speed while flowing the silver paste at a constant speed, thereby applying a silver paste of a substantially constant thickness to the side. . The thickness of the silver paste layer in the in-plane and in the side of the aluminum foil was measured to be 14 to 18 μm and 25 to 34 μm, respectively.

After laminating two aluminum foils in which an aluminum oxide layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are laminated on a lead frame, an aluminum oxide layer, a conductive polymer layer, and carbon are not formed. The portions of the paste layer and the silver paste layer were welded to the lead frame, and the laminated aluminum foil was encapsulated with an epoxy resin to fabricate a wafer of the capacitor.

The results of the capacitors evaluated by the LCR tester were 101.5 μF for the 120 Hz capacitor and 7.4 mΩ for the ESR system at 100 kHz. Further, as a result of measuring a leakage current by applying 2 V to 100 capacitors, there were 100 capacitors having a leakage current of 5 μA or less.

(Comparative Example 3)

First, the aluminum foil in which the conductive polymer layer and the carbon paste layer were formed in the same manner as in Example 4 was immersed in the same silver paste as in Example 4 using a stylus as a bristles, and the silver paste was not sufficiently removed. In the case of coating, the pen is pressed and pressed to dry the foil. The thickness distribution of the silver paste layer in the aluminum foil was measured, and the thickness of the silver paste layer was 8 to 55 μm.

Next, a wafer of a capacitor was fabricated in the same manner as in Example 4, and the result of the capacitor was evaluated by an LCR tester, which was 103.3 μF at 120 Hz and 7.7 mΩ at 100 kHz for ESR. Further, as a result of measuring a leakage current by applying 2 V to 100 capacitors, there were 100 capacitors having a leakage current of 5 μA or less.

(Comparative Example 4)

First, an aluminum foil having a conductive polymer layer and a carbon paste layer formed in the same manner as in Example 4 was coated with the same silver paste as in Example 4 by dipping, and dried. As a result of measuring the thickness distribution of the silver paste layer in the surface of the aluminum foil, the thickness of the silver paste layer was 25 to 37 μm. Further, as a result of measuring the thickness distribution of the silver paste layer in the edge of the aluminum foil, the thickness of the silver paste layer was 12 to 40 μm.

Next, a wafer of a capacitor was fabricated in the same manner as in Example 4, and the result of the capacitor was evaluated by an LCR tester, which was 103.3 μF at 120 Hz and 25.7 mΩ at 100 kHz ESR. Further, as a result of measuring a leakage current by applying 2 V to 100 capacitors, there were 100 capacitors having a leakage current of 5 μA or less.

The evaluation results of the capacitors obtained in Examples 4 and 5 and Comparative Examples 3 and 4 are shown in Table 2.

As shown in the above examples, according to the present invention, electrical characteristics, particularly ESR, are improved, and the thickness distribution of the silver paste layer is also remarkably improved. That is, according to the present invention, as shown in the above examples, it is possible to obtain a low ESR (equivalent series resistance) in which the edge portion has a sufficient layer thickness while the layer thickness of the face is suppressed and the capacitance per unit volume is increased. Solid electrolytic capacitor component. According to the present invention, as shown in the above examples, the step of immersing the anode substrate in which the oxide film layer, the conductive polymer layer, and the carbon paste layer are sequentially laminated on the surface of the anode substrate is immersed in the silver paste; The side of the anode substrate is a method of manufacturing a silver paste by brushing, and a capacitor having a small thickness unevenness of the silver paste layer and thus having a high capacitance per unit volume and a low ESR can be provided.

(Example 6)

First, an aluminum foil having a surface area increased by etching is cut into an elongated shape of 3 mm × 10 mm, and the lower half of the elongated aluminum foil and the electrode are immersed in an aqueous solution of ammonium adipate having a temperature of 80 ° C and a concentration of 10%. A voltage of 3 V was applied between them for 10 minutes to flow an electric current, thereby forming an aluminum foil, and a film of a derivative of alumina was formed on the surface of the lower half of the foil.

Then, by repeating: a step of immersing the formed aluminum foil in an isopropyl alcohol solution in which 3,4-ethylenedioxythiophene is dissolved, and immersing in sodium sulfonate The step of drying the aqueous solution in which the ammonium sulfate is dissolved is carried out, and the conductive polymer layer of the poly 3,4-ethylenedioxythiophene is adhered to the dielectric film by repeating the steps.

Further, the foil and the electrode on which the conductive polymer layer was formed were immersed in an aqueous solution of ammonium adipate having a temperature of 80 ° C and a concentration of 10%, and a voltage of 3 V was applied for 1 minute to re-form the dielectric film. The re-formed aluminum foil is immersed in a carbon paste having a composition of 7% by mass of carbon particles, 3% by mass of fluororesin, and 90% by mass of isoamyl acetate, thereby coating carbon on the surface of the aluminum foil. paste. The carbon paste has a viscosity of 60 cpoise. The coated carbon particles are composed of particles having a particle diameter of 10 to 100 nm and particles having a particle diameter of 0.8 to 8 μm, and the mass ratio is 30:70. After drying at a temperature of 130 ° C for 10 minutes, the thickness of the carbon paste layer was 9 μm, and the ratio of carbon particles contained in the carbon paste layer was 74% by mass.

Next, the carbon paste-coated aluminum foil was immersed in a silver paste composed of a ratio of 55.7 mass% of silver particles, 5.9% by mass of fluororesin, and 38.1% by mass of isoamyl acetate and 0.3% by mass of water. Thereby, a silver paste is applied to the surface of the aluminum foil. The mass ratio was measured by a thermogravimetric measuring machine (Japan Rigaku Corporation TG8129) and a Karl Fischer Moisture Titrator (KEM MKS-500). The viscosity of the silver paste is 400 cpoise. The coated silver particles have a flake shape and a length in the long axis direction of 1 to 5 μm. After drying at a temperature of 130 ° C for 10 minutes, the thickness of the silver paste layer was 13 μm, and the silver particles contained in the silver paste layer were 90% by mass.

Coating the silver paste coated with the silver paste by the dipping method, coating the silver paste coated with the immersion method, and drying at a temperature of 130 ° C for 10 minutes to apply the bristles by using the smear-painting tool. Commercially available paint pen (with a length of about 2cm) is used as the bristles. After the stylus is immersed in the silver paste, the silver paste contained in the stylus is completely removed by the wall of the container, and the tip of the stylus is gently touched by the foil from the upper side. Edge, and move the pen parallel to the side, and apply a small amount of silver paste near the side (within 1 mm from the side).

Among them, the silver paste is stored in a dryer whose humidity is adjusted to 30% or less before use. The storage temperature is 24 °C. Further, when the silver paste was applied, the ambient humidity was set to 40% and the temperature was set to 24 °C.

The aluminum foil coated with the silver paste was embedded in a two-liquid mixed-hardening resin, and the cured resin was cut at intervals of 1 mm, and the cross section of the aluminum foil was observed under an optical microscope to measure the thickness distribution of the silver paste layer in the aluminum foil. As a result, the thickness of the silver paste layer was mostly 16 μm. The thickness of the silver paste layer in the side of the aluminum foil was measured and found to be 24 to 30 μm.

After laminating two aluminum foils in which an aluminum oxide layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are laminated on a lead frame, an aluminum oxide layer, a conductive polymer layer, and carbon are not formed. The portions of the paste layer and the silver paste layer are welded to the lead frame, and the laminated aluminum foil is encapsulated with an epoxy resin, thereby manufacturing a wafer of the capacitor.

The results of evaluating 100 solid electrolytic capacitors with an LCR tester showed an average capacitance of 102.6 μF at 120 Hz and an average ESR of 6.3 mΩ at 100 kHz. Further, as a result of measuring a leak current by applying 2 V to 100 solid electrolytic capacitors, there were 100 solid electrolytic capacitors having a leakage current of 5 μA or less.

(Example 7)

In the same manner as in Example 6, a conductive polymer layer and a carbon paste layer were sequentially formed on the dielectric film formed on the aluminum foil.

Next, the carbon paste-coated aluminum foil was immersed in a silver paste composed of a ratio of 55.9 mass% of silver particles, 5.9% by mass of fluororesin, and 38.1% by mass of isoamyl acetate and 0.1% by mass of water. Thereby, a silver paste is applied to the surface of the aluminum foil. The mass ratio was measured by a thermogravimetric measuring machine (Japan Rigaku Corporation TG8129) and a Kafushi Moisture Analyzer (KEM MKS-500).

Further, in the same manner as in Example 6, a silver paste was applied to the edges of the aluminum foil by the bristles, and then a solid electrolytic capacitor was produced.

The results of evaluating 100 solid electrolytic capacitors with an LCR tester showed an average capacitance of 103.5 μF at 120 Hz and an average ESR of 6.4 mΩ at 100 kHz. Further, as a result of measuring a leak current by applying 2 V to 100 solid electrolytic capacitors, there were 100 solid electrolytic capacitors having a leakage current of 5 μA or less.

(Comparative Example 5)

In the same manner as in Example 6, a conductive polymer layer and a carbon paste layer were sequentially formed on the dielectric film formed on the aluminum foil.

Next, the carbon paste-coated aluminum foil was immersed in a silver paste composed of a ratio of 55.7 mass% of silver particles, 5.9% by mass of fluororesin, and 37.6 mass% of isoamyl acetate and 0.8% by mass of water. Thereby, a silver paste is applied to the surface of the aluminum foil. The mass ratio was measured by a thermogravimetric measuring machine (Japan Rigaku Corporation TG8129) and a Kafushi Moisture Analyzer (KEM MKS-500).

Further, in the same manner as in Example 6, a silver paste was applied to the edge of the aluminum foil by the bristles to prepare a solid electrolytic capacitor.

As a result of evaluating 100 solid electrolytic capacitors with an LCR tester, the average capacitance at 120 Hz was 101.8 μF, and the average ESR at 100 kHz was 8.4 mΩ. Further, as a result of measuring a leak current by applying 2 V to 100 solid electrolytic capacitors, there were 100 solid electrolytic capacitors having a leakage current of 5 μA or less.

(Comparative Example 6)

In the same manner as in Example 6, a conductive polymer layer and a carbon paste layer were sequentially formed on the dielectric film formed on the aluminum foil.

Next, the carbon paste-coated aluminum foil was immersed in a silver paste composed of a ratio of 55.9 mass% of silver particles, 5.9% by mass of fluororesin, and 35.1% by mass of isoamyl acetate and 3.1% by mass of water. Thereby, a silver paste is applied to the surface of the aluminum foil. The mass ratio was measured by a thermogravimetric measuring machine (Japan Rigaku Corporation TG8129) and a Kafushi Moisture Analyzer (KEM MKS-500).

Further, in the same manner as in Example 6, a silver paste was applied to the side of the aluminum foil with a brush to prepare a solid electrolytic capacitor.

The results of evaluating 100 solid electrolytic capacitors with an LCR tester showed an average capacitance of 101.8 μF at 120 Hz and an average ESR of 9.0 m Ω at 100 kHz. Further, as a result of measuring a leak current by applying 2 V to 100 solid electrolytic capacitors, there were 100 solid electrolytic capacitors having a leakage current of 5 μA or less.

The evaluation results of the solid electrolytic capacitors obtained in Examples 6 and 7 and Comparative Examples 5 and 6 are shown in Table 3.

As shown in the above examples, a silver paste having a composition having a water content of 0.5% by mass or less, particularly 0.3% by mass or less, is laminated, whereby a solid electrolytic capacitor having a sufficiently low ESR can be produced.

(Industry use possibility)

The present invention provides a solid electrolytic capacitor in which the ESR (equivalent series resistance) of the laminated structure in which the silver paste is formed on the anode substrate having the carbon paste layer on the surface is sufficiently low and the capacitance per unit volume is increased. In the present invention, a solid electrolytic capacitor element having a low ESR and a high capacitance is obtained by controlling the composition or layer thickness of a silver paste having a laminated structure formed on an anode substrate having a carbon paste layer on its surface. When a silver paste having two kinds of compositions having different wettability to the carbon paste layer is used and applied to the side (edge) portion and the face portion, the desired layer thickness can be obtained as a whole. Preferably, the silver paste layer covering the side (edge) portion of the anode substrate is thicker than the silver paste layer covering the face portion, and it is preferable to use a silver paste having a water content of 0.5 mass% or less. . The present invention provides a low ESR (equivalent series resistance) by controlling the layer thickness of the edge portion and the thickness of the layer layer when the laminated structure of the silver paste is formed on the anode substrate having the carbon paste layer on the surface. In the solid electrolytic capacitor element having a large capacitance per unit volume, when the laminated structure of the silver paste is formed on the anode base foil, a method of controlling the layer thickness of the line portion and the layer thickness of the face portion is particularly effective. In particular, a capacitor element having a small ESR (equivalent series resistance) stability and reduction and a small component thickness is particularly useful in the field of manufacturing a laminated capacitor which requires low ESR and is low in thickness. In the present invention, two kinds of silver pastes having different wettability to the carbon paste layer are used, and when a component having a low wettability is applied to the edge (edge) portion, a component having a low wettability on the face is applied. The desired layer thickness can be obtained as a whole, and this phenomenon can be widely applied to form a laminated structure in which the first coating layer and the second coating layer are sequentially formed. The solid electrolytic capacitor of the present invention and the method of manufacturing the same provide a solid electrolysis having a low ESR (Equivalent Series Resistance) with a sufficient layer thickness at the edge (edge) portion and a reduced layer thickness of the face portion and an increase in capacitance per unit volume. Capacitor component. Further, the step of immersing the anode substrate in which the oxide film layer, the conductive polymer layer and the carbon paste layer are sequentially laminated on the surface of the anode substrate is immersed in the silver paste: silver is coated with bristles on the side of the anode substrate In the manufacturing method of the paste step, a capacitor having a small thickness unevenness of the silver paste layer and thus having a high capacitance per unit volume and a low ESR can be provided. The solid electrolytic capacitor of the present invention and the method of manufacturing the same can provide a solid electrolytic capacitor element in which the ESR is sufficiently low and the capacitance per unit volume is increased.

1. . . Anode substrate

2. . . Oxidized coating

3. . . Solid electrolyte layer

4. . . Conductor layer

4a. . . Carbon paste layer

4b. . . Conductive paste layer

5. . . Masking layer

6. . . Anode lead

7. . . Cathode lead

8. . . Sealing resin

9. . . Solid electrolytic capacitor

Fig. 1 is a cross-sectional view showing a general configuration of a solid electrolytic capacitor element.

Fig. 2 is a schematic view for explaining a conventional paste coating structure in a solid electrolytic capacitor element.

Fig. 3 is a schematic view for explaining a paste-coating structure in the solid electrolytic capacitor element of the present invention.

Claims (48)

A solid electrolytic capacitor component is characterized in that an oxide film layer, a conductive polymer layer, a carbon paste layer and a silver paste layer are laminated on the surface of an anode substrate composed of a valve metal, and the layer is coated on the surface of the anode substrate. a silver paste layer in which the oxide film layer, the conductive polymer layer, and the anode base of the carbon paste layer are laminated, and the composition or layer thickness of the silver paste layer covering the anode base surface is controlled. The layer thickness of the silver paste layer covering the side (edge) portion of the anode substrate is 6 μm or more, and the layer thickness of the silver paste layer covering the surface portion is 20 μm or less. A solid electrolytic capacitor component is characterized in that an oxide film layer, a conductive polymer layer, a carbon paste layer and a silver paste layer are laminated on the surface of an anode substrate composed of a valve metal, and the layer is coated on the surface of the anode substrate. a silver paste layer in which the oxide film layer, the conductive polymer layer, and the anode base of the carbon paste layer are laminated, and the composition or layer thickness of the silver paste layer covering the anode base surface is controlled. The liquid A comprising a material for forming a silver paste layer on the anode substrate having a carbon paste layer on its surface is applied to a side edge of the anode substrate, and the material for forming the silver paste layer is contained. Further, a liquid B composed of a liquid having a higher wettability of the carbon paste layer than the liquid A is applied to the surface of the anode base to form a laminated structure. The solid electrolytic capacitor element according to claim 2, wherein the liquid A is applied to the side (edge) portion of the anode substrate and dried, and then the anode substrate is immersed in the liquid B to thereby pass the liquid B. It is applied to the face of the anode substrate to form a laminate structure. The solid electrolytic capacitor element according to claim 3, wherein the lower side (edge) portion of the anode base is immersed in the liquid A, and the liquid A is applied to the lower side (edge) portion and dried. The surface of the anode substrate is immersed in the surface B, whereby the liquid B is applied to the surface of the anode substrate to form a laminate structure. The solid electrolytic capacitor element according to claim 2, wherein the liquid B is applied to the surface of the anode substrate and dried, and then the anode substrate is immersed in the liquid A to thereby coat the side of the anode substrate with the liquid A. The (edge) portion forms a laminate structure. The solid electrolytic capacitor element according to claim 2, wherein at least one of the carbon paste layer and the silver paste forming the laminated structure is a coating layer containing a fluororesin. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the shape of the anode base is a flat foil, a plate or a rod. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the dielectric film layer provided on the surface of the anode substrate is attached to the oxide of the valve action metal itself on the surface of the valve action metal. Layer. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the valve action metal is selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and alloys based on the metals. One of the group. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the surface of the oxide film layer is laminated by a valve The anode substrate made of metal is a formed Al-foil. A solid electrolytic capacitor comprising the solid electrolytic capacitor element according to any one of claims 1 to 10. A laminated solid electrolytic capacitor characterized by comprising a laminate of a plurality of solid electrolytic capacitor elements according to any one of claims 1 to 10. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the oxide film layer, the conductive polymer layer, and the carbon paste are sequentially laminated on the surface of the anode substrate composed of the valve action metal. In the solid electrolytic capacitor element of the layer and the silver paste layer, a silver paste layer on the side (edge) portion of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is laminated on the surface of the anode substrate in this order. The silver paste layer is thicker than the face covering the anode substrate. The solid electrolytic capacitor element according to claim 13, wherein the shape of the anode base is a flat foil, a plate or a rod. The solid electrolytic capacitor element according to claim 13, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself on the surface of the valve action metal. The solid electrolytic capacitor element according to claim 13, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and an alloy based on the metal. The solid electrolytic capacitor element according to claim 13, wherein the anode base body made of a valve action metal having an oxide film layer laminated on its surface is an aluminized foil. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the oxide film layer, the conductive polymer layer, and the carbon paste are sequentially laminated on the surface of the anode substrate composed of the valve action metal. In the solid electrolytic capacitor element of the layer and the silver paste layer, the thickness of the silver paste layer on the side (edge) portion of the anode substrate on which the oxide film layer, the conductive polymer layer, and the carbon paste layer are laminated on the surface of the anode substrate is 10μm or more. The solid electrolytic capacitor element according to claim 18, wherein the silver paste of the side of the anode substrate of the oxide film layer, the conductive polymer layer, and the carbon paste layer is laminated on the surface of the anode substrate. The layer thickness is 10 to 200 μm. The solid electrolytic capacitor element according to claim 18, wherein the shape of the anode base is a flat foil, a plate or a rod. The solid electrolytic capacitor element according to claim 18, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself on the surface of the valve action metal. The solid electrolytic capacitor element according to claim 18, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and an alloy based on the metal. The solid electrolytic capacitor element according to claim 18, wherein the anode base body made of a valve action metal having an oxide film layer laminated on its surface is an aluminized foil. The solid electrolytic capacitor element according to any one of the items 1 to 6, wherein the oxide film layer, the conductive polymer layer, and the carbon paste are sequentially laminated on the surface of the anode substrate composed of the valve action metal. Layer and In the solid electrolytic capacitor element of the silver paste layer, a silver paste having a water content of the silver paste of 0.5% by mass or less is laminated. The solid electrolytic capacitor element according to claim 24, wherein the water content is 0.3% by mass or less. The solid electrolytic capacitor element according to claim 24, wherein the shape of the anode base is a flat foil, a plate or a rod. The solid electrolytic capacitor element according to claim 24, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself on the surface of the valve action metal. The solid electrolytic capacitor element according to claim 24, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium and an alloy based on the metal. The solid electrolytic capacitor element according to claim 24, wherein the anode base body composed of the valve action metal laminated on the surface of the oxide film layer is aluminized to a foil. A method for forming a laminated structure, which is a method for forming a laminated structure in which a second coating layer is formed on a foil having a first coating layer on the surface thereof, and is characterized in that: a liquid A containing a material for forming a second coating layer is provided a step of applying to the side (edge) portion of the foil; and applying a liquid B containing a material for forming the second coating layer and having a higher wettability to the first coating layer than the liquid of the A coating layer to the foil The steps of the face of the piece. The method for forming a laminate structure according to claim 30, wherein the liquid A is applied to a side (edge) portion of the foil and dried, and then the foil is immersed in the liquid B to coat the liquid B. Cover the face of the foil. The method for forming a laminate structure according to claim 31, wherein the lower edge (edge) portion of the foil is immersed in the liquid A and applied to the lower edge (edge) portion, and dried, and then the foil is contained. The face of the sheet was immersed in the liquid B, and the liquid B was applied to the face of the foil. The method for forming a laminate structure according to claim 30, wherein the liquid B is applied to a surface of the foil and dried, and then the foil is immersed in the liquid A to cover the side of the foil with the liquid A. (Edge) Department. The method for forming a laminate structure according to any one of the items 30 to 33, wherein at least one of the first coating layer and the second coating layer is a coating layer containing a fluororesin. The method for forming a laminate structure according to any one of claims 30 to 33, wherein the first coating layer is a carbon paste layer, and the second coating layer is a conductive paste layer other than the carbon paste. A method for producing a solid electrolytic capacitor element, which is a method for manufacturing a solid electrolytic capacitor element in which a carbon paste layer and a conductive paste layer are sequentially formed on a solid electrolyte layer of a solid electrolytic capacitor element having a solid electrolyte layer as a cathode portion It is characterized in that the lamination structure of the 35th article of the patent application is used in the lamination step of the carbon paste layer and the conductive paste layer. The method for producing a solid electrolytic capacitor element according to claim 36, wherein the conductive paste is a silver paste. A solid electrolytic capacitor component produced by the method of claim 37 of the patent application. A solid electrolytic capacitor includes the patent application scope 38 The solid electrolytic capacitor component of the item. A laminated solid electrolytic capacitor characterized by comprising a laminate comprising a plurality of solid electrolytic capacitor elements of claim 38. A method for producing a solid electrolytic capacitor element, which is a method for manufacturing a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are sequentially laminated on an anode substrate surface composed of a valve action metal It is characterized by laminating a silver paste having a water content of 0.5% by mass or less. The method for producing a solid electrolytic capacitor element according to claim 41, wherein the water content is 0.3% by mass or less. The method for producing a solid electrolytic capacitor element according to claim 41, wherein the shape of the anode base is a flat foil, a plate or a rod. The method for producing a solid electrolytic capacitor element according to claim 41, wherein the dielectric film layer provided on the surface of the anode substrate is provided on the oxide layer of the valve action metal itself on the surface of the valve action metal. The method for producing a solid electrolytic capacitor element according to claim 41, wherein the valve action metal is one selected from the group consisting of aluminum, tantalum, titanium, niobium, zirconium, and an alloy based on the metal. . The method for producing a solid electrolytic capacitor element according to claim 41, wherein the anode base body composed of the valve action metal laminated on the surface of the oxide film layer is aluminized to a foil. a silver paste formed on an anode base composed of a valve action metal A laminate structure of a solid electrolytic capacitor element in which an oxide film layer, a conductive polymer layer, a carbon paste layer, and a silver paste layer are laminated in this order, wherein the water content of the silver paste is 0.5% by mass or less . For example, the silver paste of claim 47, wherein the water content is 0.3% by mass or less.