JP2009224688A - Solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality solid electrolytic capacitor which is compact and improves performance and environmental resistance. <P>SOLUTION: A solid electrolytic capacitor is formed so that a cathode electrode plate 11a and an anode electrode plate 11b on a substrate 1 are positioned inside an outer circumferential part of a capacitor element 2, namely, so that projection parts, with respect to the substrate 1, of the cathode electrode plate 11a and the anode electrode plate 11b when watched from an upper surface of the substrate 1 are included in a projection part of the capacitor element 2. Meanwhile, if the projection parts of the cathode electrode plate 11a and the anode electrode plate 11b are not included but are protruded from the projection part of the capacitor element 2 partially, namely, they extend outside from the outer circumferential part, the extending parts are covered with insulating resins 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bottom electrode type solid electrolytic capacitor including a substrate and a capacitor element and having an electrode directly drawn on a substrate mounting surface.

  In recent years, with the downsizing and thinning of various electronic devices, solid electrolytic capacitors can be mounted at high density, and the so-called bottom electrode type, in which the anode and cathode terminals are located on the bottom surface of the main body, improves environmental resistance. For this reason, solid electrolytic capacitors are often used that are sealed with exterior resin and are made small, large capacity, and have improved frequency characteristics by using aluminum, tantalum, niobium or the like as a valve action metal.

  3A and 3B are diagrams showing the positional relationship between the capacitor element and the electrode plate in a conventional solid electrolytic capacitor (comparative example). FIG. 3A is a schematic cross-sectional view, and FIG. Show.

  As shown in FIG. 3A, the solid electrolytic capacitor has a structure in which the capacitor element 2 is mounted on the substrate 1 and then the outer peripheral portion of the capacitor element is sealed with an exterior resin 18.

The capacitor element 2 includes a capacitor element anode portion 15 formed of a part of one side of the valve action metal 3, and a first dielectric layer 4a which is an oxide film of the valve action metal 3 on a portion excluding the capacitor element anode portion 15. And the second dielectric layer 4b, the first conductive polymer layer 5a and the second conductive polymer layer 5b, which are solid electrolytes, the first graphite layer 6a and the second graphite layer 6b, and silver 7. The valve metal 3 is sequentially laminated so as to sandwich the valve metal 3 from above and below, and the outermost silver 7 is used as the capacitor element cathode portion 14.
Further, a resist band 8 is formed between the capacitor element anode portion 15 and the capacitor element cathode portion 14 in order to ensure insulation between the two electrodes, and further, a conductive layer is formed on the lower surface of the capacitor element anode portion 15, that is, on the mounting surface side. The lead frame 9 is bonded.

  On the other hand, an anode electrode plate 11b and a cathode electrode plate 11a are formed on the upper surface of the substrate 1 so as to face the lower surfaces of the lead frame 9 and the capacitor element cathode portion 14, respectively, and the anode electrode plate 11b is formed on the lower surface. And an external anode terminal 13b connected via the second through via 12b and an external cathode terminal 13a connected to the cathode electrode plate 11a via the first through via 12a.

  And, via the conductive adhesive 10, the lead frame 9 and the anode electrode plate 11b, while the lower surface side of the capacitor element cathode portion 14 and the cathode electrode plate 11a are respectively connected, finally, The outer periphery of the capacitor element 2 is sealed with an exterior resin 18. Such a solid electrolytic capacitor is disclosed in Patent Document 1, for example.

JP 2002-110458 A

As shown in FIG. 3B, the substrate of the capacitor element 2 when viewed from the upper surface for the reason of visibility of the bonding state between the capacitor element 2 and the anode electrode plate 11b and the cathode electrode plate 11a on the substrate 1. The projected portions of the anode electrode plate 11b and the cathode electrode plate 11a protrude from the projected portion for 1 and are generally formed in this way.
That is, the anode electrode plate 11 b and the cathode electrode plate 11 a are formed to extend outward from the outer peripheral end of the capacitor element 2, and the electrode plate exposed portion 16 exists.

  In such an arrangement method, for the purpose of increasing the capacity, if the capacitor element is enlarged without changing the external dimensions of the solid electrolytic capacitor, the thickness of the exterior resin is reduced, and the area where the exterior resin is in contact with the electrode plate is Since it is larger than the area in contact with the insulating resin layer such as a resist layer disposed on the outer periphery of the electrode plate on the substrate, the bonding strength between the exterior resin and the substrate is reduced, and the exterior resin is peeled off and missing. The electrode portion is exposed and has the disadvantage of deteriorating product quality, particularly environmental resistance, due to oxidation, electrolytic corrosion, etc., which has hindered the increase in capacity.

  An object of the present invention is to solve the above-mentioned problems and to provide a high-quality solid electrolytic capacitor excellent in small size, high performance, and environmental resistance.

  In order to solve the above-mentioned problems, the electrode portion on the substrate is included in the projection portion of the capacitor element when the electrode portion on the substrate is viewed from the inner periphery of the capacitor element, that is, when viewed from the upper surface of the substrate. If the projection part of the electrode part protrudes without being included in the projection part of the capacitor element, that is, if it extends outside the outer peripheral part, the extension part is insulated resin. Even if the capacitor element is enlarged, the outer peripheral portion of the capacitor element ensures a bonding portion between the exterior resin and the insulating layer (resist layer) on the substrate containing the insulating resin, and the resins are strong. Since it is in close contact with the outer casing, it is possible to prevent the outer casing resin from being peeled off and missing, and to completely cover the outer casing resin.

  According to the present invention, there is provided a solid electrolytic capacitor in which a capacitor element is mounted on an upper surface of a substrate and the capacitor element is sealed with an exterior resin. The capacitor element includes an anode portion made of a valve metal and the anode portion. A first dielectric layer, a first solid electrolyte layer, a first graphite layer, a first cathode part, and a part of the lower surface of the anode part are sequentially laminated on a part of the upper surface. An anode electrode comprising a dielectric layer, a second solid electrolyte layer, a second graphite layer, and a second cathode portion, and formed between a portion where the upper and lower surfaces of the anode portion are exposed and the substrate A cathode electrode plate formed between the second cathode portion and the substrate, the plate and an external anode terminal formed on the lower surface of the substrate being connected via a first through via; The external cathode terminal formed on the lower surface of the substrate has a second through via. When the surfaces of the anode portion, the anode electrode plate, and the cathode electrode plate that face each of the substrates are projected onto the substrate, the anode electrode plate and the cathode electrode plate The solid electrolytic capacitor is obtained in which the projection part is included in the projection part of the anode part.

  According to the present invention, there is provided a solid electrolytic capacitor in which a capacitor element is mounted on an upper surface of a substrate and the capacitor element is sealed with an exterior resin. The capacitor element includes an anode portion made of a valve metal and the anode portion. A first dielectric layer, a first solid electrolyte layer, a first graphite layer, a first cathode part, and a part of the lower surface of the anode part are sequentially laminated on a part of the upper surface. An anode electrode comprising a dielectric layer, a second solid electrolyte layer, a second graphite layer, and a second cathode portion, and formed between a portion where the upper and lower surfaces of the anode portion are exposed and the substrate A cathode electrode plate formed between the second cathode portion and the substrate, the plate and an external anode terminal formed on the lower surface of the substrate being connected via a first through via; The external cathode terminal formed on the lower surface of the substrate has a second through via. When the surfaces of the anode portion, the anode electrode plate, and the cathode electrode plate that face each of the substrates are projected onto the substrate, the anode electrode plate and the cathode electrode plate When the projection part is not included in the projection part of the anode part, a solid electrolytic capacitor is obtained in which at least the part not included in the anode electrode plate or the cathode electrode plate is covered with an insulating resin. .

  In the substrate type solid electrolytic capacitor of the present invention, the projection portion of the electrode plate onto the substrate is the projection portion of the capacitor element when viewed from the upper surface of the substrate with respect to the size and positional relationship between the capacitor element and the electrode plate on the substrate mounting surface. If the electrode plate projection part is not included in the projection part of the capacitor element and is formed to extend outside, the part of the electrode plate projection part that is not included, that is, the electrode plate By covering at least the exposed extended portion with an insulating resin, the adhesion between the electrode plate and the exterior resin is generally poor, so the insulating resin blocks the air intrusion path that occurs at the interface between the substrate and the capacitor element. Even if the outer peripheral gap becomes narrow and the thickness of the exterior resin decreases, it adheres firmly to the insulating resin that coats the substrate. A decrease in impact and environmental resistance can be prevented.

  Further, since the capacitor element can be made as close as possible to the size of the substrate without changing the external dimensions, that is, the thickness of the exterior resin can be made as thin as possible, the capacity can be increased.

  Furthermore, the surface of the electrode plate formed on the substrate is plated with a metal material such as gold, silver, copper, or nickel, thereby improving the bondability between the anode and cathode of the capacitor element and increasing the bonding strength. At the same time, the contact resistance is small, that is, the equivalent series resistance (ESR) can be reduced.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing the positional relationship between an electrode plate on a substrate and a capacitor element in a solid electrolytic capacitor of the present invention. FIG. 1 (a) is a schematic sectional view, and FIG. 1 (b) is a top transmission diagram. Show.

  The capacitor element 2 includes one end portion of a plate-like or foil-like valve metal 3 serving as a base material as a capacitor element anode portion 15, and a lead frame is formed on the lower surface of the capacitor element anode portion 15, that is, a part on the mounting surface side. 9 are joined and electrically connected to the anode electrode plate 11b of the substrate 1 through a conductive adhesive 10 such as a paste containing an alloy. On the other hand, a capacitor element cathode portion 14 is formed on the portion of the valve metal 3 excluding the capacitor element anode portion 15 so as to be adjacent to the capacitor element anode portion 15 and sandwich an insulating portion such as a resist band 8. .

  The remaining portions of the valve metal 3 excluding the capacitor element anode portion 15 and the resist band 8 are a first dielectric layer 4a and a second dielectric layer, which are oxide films of the valve metal. 4b, first conductive polymer layer 5a and second conductive polymer layer 5b which are solid electrolytes, first graphite layer 6a and second graphite layer 6b, and silver 7 which is the capacitor element cathode portion 14 Are sequentially stacked so that the anode portions are sandwiched from above and below, respectively. A part of the capacitor element cathode portion 14 is electrically connected to the cathode electrode plate 11a formed on the substrate 1 by a printing method or the like using a conductive adhesive 10 such as a paste containing an alloy. Yes.

The cathode electrode plate 11a and the anode electrode plate 11b penetrate the substrate 1 and are externally connected to the external cathode terminal 13a via the first through via 12a and the second through via 12b filled with a conductive material (not shown). Each is connected to the anode terminal 13b.
Further, the outer peripheral portion of the capacitor element 2 on the substrate 1 is sealed with an exterior resin 18.

  As shown in FIG. 1, the size of the cathode electrode plate 11a and the anode electrode plate 11b formed on the substrate 1 and the positional relationship with the capacitor element 2 are such that each electrode plate is inside the outer peripheral edge of the capacitor element 2, that is, the substrate 1 When viewed from above, the projections of both electrode plates are arranged so as to be included in the projection of the capacitor element 2.

  With this configuration, the exterior resin 18 can easily flow into the gap at the lower periphery of the capacitor element 2, and even if the outer circumference gap between the substrate 1 and the capacitor element is narrowed and the thickness of the exterior resin 18 is reduced, Since it adheres firmly to the insulating resin coating the substrate 1, it is possible to prevent the exterior resin 18 from being peeled off, missing, or adversely affecting the internal electrode joint.

  2A and 2B are diagrams showing the positional relationship between the electrode plate on the substrate and the capacitor element in the solid electrolytic capacitor of the present invention. FIG. 2A is a schematic cross-sectional view, and FIG. Each is shown.

FIG. 2 shows a case where the basic structure is the same as that of the solid electrolytic capacitor shown in FIG. 1, and only the size and arrangement position of the electrode plate are different. That is, the size of the cathode electrode plate 11 a and the anode electrode plate 11 b formed on the substrate 1 and the positional relationship with the capacitor element 2 are such that at least a part of the cathode electrode plate 11 a extends outside the outer peripheral end of the capacitor element 2. The electrode plate exposed portion 16 that is disposed and not covered by the capacitor element 2 is covered with an insulating resin 17.
Here, both of the electrode plates are arranged so that a part of them extends outside the outer peripheral end of the capacitor element 2 on the substrate 1, but only a part of at least one of the electrode plates is on the outside. The extending portion may be arranged so as to extend, and the extending portion may be covered with the insulating resin 17.

  The substrate 1 is preferably made of a highly heat-resistant insulating material, and any of a resin system such as a glass epoxy material, a BT resin, a polyimide, a liquid crystal polymer, or a ceramic system such as alumina may be used. It is more preferable to use a general-purpose glass epoxy material that is effective in terms of flexibility and cost.

  The valve metal 3 (= capacitor element anode portion 15) serving as a base material is preferably a plate or foil made of metal such as aluminum, tantalum, niobium or titanium.

  The first dielectric layer 4a and the second dielectric layer 4b are oxide films formed on the metal surface by immersing the valve metal 3 in an electrolytic solution and flowing an electric current. It is preferable to form a film by appropriately adjusting the current.

  The first conductive polymer layer 5a and the second conductive polymer layer 5b, which are solid electrolytes, preferably use polythiophene or polypyrrole.

  The first graphite layer 6a and the second graphite layer 6b are composed of the silver 7 laminated on the upper layer thereof, the first conductive polymer layer 5a which is a solid electrolyte formed on the lower layer, and the second conductive polymer. This is to improve the bonding with the layer 5b.

  The silver 7 (= capacitor element cathode portion 14) is preferably formed by applying a paste-like material generally used as a cathode electrode material of the capacitor element 2 with a dispenser and drying and curing.

  The resist band 8 is made of a material having high heat resistance, and may be any of a thermosetting resin such as epoxy or silicone, or a thermoplastic resin such as polyimide, and a paste or liquid is preferably used. In consideration of film processability, a silicone-based thermosetting resin is more preferable. The coating method is preferably set to a thickness of 10 to 30 μm, which is a sufficient thickness to ensure the function of the resist, using a common method such as dipping, spraying, coating, or printing.

  The lead frame 9 is preferably made of a conductive material made of metal such as copper, aluminum, stainless steel, or an alloy thereof, and the surface of which is plated with gold, tin or the like.

  The conductive adhesive 10 is preferably applied by using a dispenser with an epoxy-based paste resin containing metal powder such as gold, silver and copper.

  The cathode electrode plate 11a and the anode electrode plate 11b are formed by a general printing method such as gravure printing or screen printing after bonding a conductive foil body made of metal such as copper or aluminum to the upper surface of the substrate 1. Resist printing is performed, and an etching process is performed. Not only the above method but also a conductive paste may be printed.

  The external cathode terminal 13a and the external anode terminal 13b are formed by a general printing method such as gravure printing or screen printing after a conductive foil body made of metal such as copper or aluminum is bonded and attached to the lower surface of the substrate 1. Resist printing is performed, and an etching process is performed. Not only the above method but also a conductive paste may be printed.

  The insulating resin 17 is made of a material having high heat resistance, like the resist band 8, and may be any of an epoxy-based or silicone-based thermosetting resin, a polyimide-based thermoplastic resin, or a paste or liquid. Is preferably used, and a silicone-based thermosetting resin is more preferable in consideration of film forming processability. The coating method is preferably set to a thickness of 10 to 30 μm, which is a sufficient thickness to ensure the function of the resist, using a common method such as dipping, spraying, coating, or printing.

  The exterior resin 18 is a general-purpose sealing resin and may be any resin that can withstand the usage environment, and may be any one of epoxy-based, phenol-based thermosetting resins, PP, PS, and other thermoplastic resins. However, it is preferable to select appropriately considering heat resistance and workability. In consideration of solder reflow mounting property on the power supply board, an epoxy-based thermosetting resin is more preferable. The sealing method may be any method such as an injection method or a transfer method.

  Hereinafter, it explains in full detail using an Example.

Example 1
As the substrate 1, a material made of glass epoxy resin, a size of 7.5 × 5.8 mm, and a thickness of 0.1 mm was used. Further, a cathode electrode plate 11a having a size of 4.5 × 4.5 mm and an anode electrode plate 11b having a size of 0.6 × 4.5 mm are provided on the upper surface of the substrate 1, and a size is provided on the lower surface. A 4.0 × 4.5 mm external cathode terminal 13a and a 0.5 × 4.5 mm external anode terminal 13b were each formed by a printing method with a plate thickness of 50 μm.
Further, the arrangement positions of the cathode electrode plate 11a and the anode electrode plate 11b were formed so as to be completely covered with the capacitor element 2 when viewed from the inner side of the mounting area of the capacitor element 2, that is, the mounting upper surface.

Since the capacitor element 2 is the same as the manufacturing method by a known technique, it is simplified and aluminum foil is used as the valve action metal 3, and the size is 6.5 × 5.0 mm and the thickness is 50 μm.
The first dielectric layer 4a and the second dielectric layer 4b are 50 μm thick as oxide films on the upper and lower surfaces within a one-side area of size 5.0 × 5.0 mm, respectively, and the first conductive layer is a solid electrolyte. The molecular layer 5a and the second conductive polymer layer 5b are each 15 μm thick, the conductive first graphite layer 6a and the second graphite layer 6b are each 20 μm thick, and the silver 7 is 20 μm thick. The outermost silver 7 was used as the capacitor element cathode portion 14.
On the other hand, the portion of the size 1.0 × 5.0 mm opposite to the capacitor element cathode portion 14 is used as a capacitor element anode portion 15, and the gap between the capacitor element cathode portion 14 and the capacitor element anode portion 15 is 0.5 × 5. A resist band 8 having a thickness of 0.1 mm was formed at 0.0 mm in order to ensure insulation between the two electrodes. Further, a lead frame 9 made of tin-plated copper alloy was used and joined to the lower surface of the anode part by resistance welding or laser welding.
In this way, a capacitor element 2 having a size of 6.5 × 5.0 mm and a height of 0.3 mm was obtained.

Further, the surfaces of the cathode electrode plate 11a and the anode electrode plate 11b are subjected to gold plating so as to improve the bondability, and further melted by heat treatment through an epoxy adhesive containing a silver alloy as the conductive adhesive 10. Thus, the capacitor element 2 was electrically connected.
Thereafter, the outer peripheral portion of the capacitor element 2 is sealed by a transfer method using an epoxy-based thermosetting resin (manufactured by Sumitomo Bakelite Co., Ltd.) as the exterior resin 18, and has a size of 7.5 × 5.8 mm and a height of 0.5 mm. The solid electrolytic capacitor shown in FIG. 1 was obtained.

(Example 2)
Using the same material and the same parts as in Example 1, only the arrangement position and size of the cathode electrode plate 11a and the anode electrode plate 11b are changed, that is, a part of each electrode plate is outside the outer peripheral end of the capacitor element 2. Each electrode plate is extended by 0.2 mm on each side, protrudes from a part of the electrode plate exposed portion 16 that is not covered with this capacitor element, and the insulating layer around each side by 50 μm, and is pasted as insulating resin 17 An epoxy resin (manufactured by Taiyo Ink Co., Ltd.) was applied.
Thereafter, the outer peripheral portion of the capacitor element 2 is sealed by a transfer method using an epoxy-based thermosetting resin (manufactured by Sumitomo Bakelite Co., Ltd.) as an exterior resin 18, and the size is 7.5 × 5.8 mm and the height is 0.5 mm. The solid electrolytic capacitor shown in FIG. 2 was obtained.

(Comparative example)
As a comparative example, the conventional solid electrolytic capacitor shown in FIG. 3 was manufactured using the same members as described above, except that only the size and arrangement method of the cathode electrode plate 11a and the anode electrode plate 11b were changed. That is, the electrode plate was disposed so that the electrode plate exposed portion 16 of the capacitor element 2 extended outward by 0.2 mm on each side.
Thereafter, the outer peripheral portion of the capacitor element 2 is sealed by a transfer method using an epoxy-based thermosetting resin (manufactured by Sumitomo Bakelite Co., Ltd.) as an exterior resin 18, and the size is 7.5 × 5.8 mm and the height is 0.5 mm. The solid electrolytic capacitor shown in FIG. 3 was obtained.

  With respect to each solid electrolytic capacitor produced in the above manner, the first embodiment according to the present invention shown in FIG. 1, the second embodiment according to the present invention shown in FIG. 2, and the comparative example shown in FIG. A high temperature no-load test (n = 10 to 2000 h) was performed, and the average value of the rate of change (Tc = 25 ° C.) when the initial value was set to 1 for 100 kHz equivalent series resistance (ESR) was compared in time series. The results are shown in Table 1.

  As shown in Table 1, Example 1 and Example 2 of the present invention have a smaller rate of change in equivalent series resistance (ESR) than that of the comparative example, that is, contact resistance is stable and very excellent characteristics and quality. It was found that can be secured.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

  With the solid electrolytic capacitor of the present invention, it is possible to reduce the size, increase the capacity, improve the performance, and improve the quality, and respond to the increasingly diverse electronic equipment market where demands for further downsizing and higher performance become stricter in the future. Become.

The figure which shows the positional relationship of the capacitor | condenser element and electrode plate in the solid electrolytic capacitor (Example 1) of this invention. 1A is a schematic cross-sectional view, and FIG. 1B is a top transparent view. The figure which shows the positional relationship of the capacitor | condenser element and electrode plate in the solid electrolytic capacitor (Example 2) of this invention. 2A is a schematic sectional view, and FIG. 2B is a top transparent view. The figure which shows the positional relationship of the capacitor | condenser element and electrode plate in the conventional solid electrolytic capacitor (comparative example). 3A is a schematic sectional view, and FIG. 3B is a top transparent view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Capacitor element 3 Valve action metal 4a First dielectric layer 4b Second dielectric layer 5a First conductive polymer layer 5b Second conductive polymer layer 6a First graphite layer 6b Second Graphite layer 7 Silver 8 Resist strip 9 Lead frame 10 Conductive adhesive 11a Cathode electrode plate 11b Anode electrode plate 12a First through via 12b Second through via 13a External cathode terminal 13b External anode terminal 14 Capacitor element cathode portion 15 Capacitor element anode portion 16 Electrode plate exposed portion 17 Insulating resin 18 Exterior resin

Claims (2)

  A solid electrolytic capacitor in which a capacitor element is mounted on an upper surface of a substrate and the capacitor element is sealed with an exterior resin, the capacitor element being an anode portion made of a valve metal, and a part of the upper surface of the anode portion, A first dielectric layer, a first solid electrolyte layer, a first graphite layer, a first cathode portion, and a second dielectric layer sequentially laminated on a part of the lower surface of the anode portion; An anode electrode plate comprising a second solid electrolyte layer, a second graphite layer, and a second cathode portion, the anode electrode plate formed between a portion where the upper and lower surfaces of the anode portion are exposed, and the substrate; The external anode terminal formed on the lower surface is connected via the first through via, and is formed on the lower surface of the substrate, the cathode electrode plate formed between the second cathode portion and the substrate. The external cathode terminal connected is connected through the second through via When the surfaces of the anode portion, the anode electrode plate, and the cathode electrode plate that face each of the substrates are projected onto the substrate, the projection portions of the anode electrode plate and the cathode electrode plate are A solid electrolytic capacitor characterized by being enclosed in a projection part of an anode part.   A solid electrolytic capacitor in which a capacitor element is mounted on an upper surface of a substrate and the capacitor element is sealed with an exterior resin, the capacitor element being an anode portion made of a valve metal, and a part of the upper surface of the anode portion, A first dielectric layer, a first solid electrolyte layer, a first graphite layer, a first cathode portion, and a second dielectric layer sequentially laminated on a part of the lower surface of the anode portion; An anode electrode plate comprising a second solid electrolyte layer, a second graphite layer, and a second cathode portion, the anode electrode plate formed between a portion where the upper and lower surfaces of the anode portion are exposed, and the substrate; The external anode terminal formed on the lower surface is connected via the first through via, and is formed on the lower surface of the substrate, the cathode electrode plate formed between the second cathode portion and the substrate. The external cathode terminal connected is connected through the second through via When the surfaces of the anode portion, the anode electrode plate, and the cathode electrode plate that face each of the substrates are projected onto the substrate, the projection portions of the anode electrode plate and the cathode electrode plate are A solid electrolytic capacitor comprising: an anode electrode plate or a cathode electrode plate that is not encapsulated in a projection portion of an anode portion; and at least the unencapsulated portion of the anode electrode plate or the cathode electrode plate is covered with an insulating resin.

Images