Capacitor

Abstract

To provide a capacitor that improves durability against voltages.SOLUTION: Provided is a single-layer capacitor 1, where a first electrode 3A and a common electrode part 4 face each other via an element body 2 so that a first capacitor part 21 is formed. A second electrode 3B and the common electrode part face each other via the element body so that a second capacitor part 22 is formed. The first capacitor part and the second capacitor part are connected in series. Since the first electrode and the second electrode are mutually insulated on the surface of the element body, it is possible to prevent a current from flowing between the two. Therefore, a current flowing between the first electrode and the second electrode to which lead terminals 6A, 6B are connected, respectively, flows in the first capacitor part and the second capacitor part. Thus, it is possible to form a plurality of series-connected capacitor parts in one element body and lower the voltage applied to each individual capacitor part, resulting in improvement of the durability against voltages as a single-layer capacitor.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a capacitor.

Background Art

[0002] As a conventional capacitor, the one described in Patent Document 1 is known. This capacitor includes two lead wires each having a flat element body constituting the element body of the electronic component, electrode films formed on the front and back surfaces of the substrate, respectively, a connection portion electrically connected to the electrode films, and a lead leg portion extending outward from the connection portion, and an exterior resin covering the periphery of the element body to which the connection portions of the lead wires are connected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the capacitor as described above, a capacitor portion is formed between the electrode on the main surface formed on one side of the element body and the electrode on the other main surface. Thus, the above-described capacitor was composed of one capacitor portion.

[0005] In capacitors, it has been required to improve the resistance to voltage.

[0006] An object of the present invention is to provide a capacitor capable of improving the resistance to voltage.

Means for Solving the Problems

[0007] A capacitor according to one embodiment of the present invention includes a body having a pair of main surfaces facing each other, a first electrode, a second electrode, and a common electrode portion provided on one of the main surfaces of the body, a first lead terminal connected to the first electrode by soldering, and a second lead terminal connected to the second electrode by soldering. The first capacitor portion is formed by the first electrode and the common electrode portion facing each other through the body, and the second capacitor portion is formed by the second electrode and the common electrode portion facing each other through the body. The first capacitor portion and the second capacitor portion are connected in series, and the first electrode and the second electrode are insulated from each other on the surface of the body.

[0008] This capacitor includes a first lead terminal connected to the first electrode and a second lead terminal connected to the second electrode. Therefore, the capacitor can be mounted on a circuit board by the lead terminals. In addition to these first and second electrodes, the capacitor includes a common electrode portion. The first capacitor portion is formed by the first electrode and the common electrode portion facing each other through the body. Also, the second capacitor portion is formed by the second electrode and the common electrode portion facing each other through the body. These first and second capacitor portions are connected in series. On the other hand, since the first electrode and the second electrode are insulated from each other on the surface of the body, the flow of current between them can be suppressed. The current flowing between the first electrode and the second electrode to which the lead terminals are connected does not flow directly between the electrodes but flows in series through the first capacitor portion and the second capacitor portion. In this way, a plurality of capacitor portions connected in series can be formed in one body. Since the voltage applied to each capacitor portion can be reduced, the resistance of the capacitor to voltage can be improved. From the above, the resistance of the capacitor to voltage can be improved.

[0009] The first electrode and the second electrode are provided on one main surface, the common electrode portion is provided on the other main surface, has a common electrode facing the first electrode and the second electrode, and the first capacitor portion and the second capacitor portion are connected in series via the common electrode. The first electrode and the second electrode may be insulated from each other on one main surface. In this way, two capacitor portions directly connected in one element body can be formed.

[0010] The common electrode portion has a plurality of common electrodes, and the plurality of common electrodes may face each other via the element body. In this case, by using a plurality of common electrodes, three or more capacitor portions can be formed.

[0011] The common electrode portion has a first common electrode and a second common electrode. When the first electrode and the first common electrode face each other via the element body, the first capacitor portion is formed. When the second electrode and the second common electrode face each other via the element body, the second capacitor portion is formed. When the first common electrode and the second common electrode face each other via the element body, the third capacitor portion may be formed. In this case, three capacitor portions connected in series in one element body can be formed.

[0012] When viewed from the first direction in which a pair of main surfaces face each other, the inner peripheral side portions of the first electrode, the second electrode, the first common electrode, and the second common electrode form a predetermined angle. The angles of the first electrode and the second electrode are approximately 120°, and the angles of the first common electrode and the second common electrode may be approximately 240°. In this case, the capacitances of the three capacitor portions can be made substantially equal. Therefore, it is possible to suppress variations in the voltage resistance of each capacitor portion.

[0013] The first electrode and the second common electrode may be provided on one main surface, and the second electrode and the first common electrode may be provided on the other main surface. In this case, the first lead terminal is arranged on the one main surface side, and the second lead terminal is arranged on the other main surface side. Thereby, a structure in which the element body is sandwiched by the lead terminals can be achieved. Therefore, the thickness of the exterior resin on each main surface can be made uniform.

[0014] The common electrode portion has a first common electrode, a second common electrode, and a third common electrode. When the first electrode and the first common electrode face each other through the base body, a first capacitor portion is formed. When the second electrode and the second common electrode face each other through the base body, a second capacitor portion is formed. When the first common electrode and the third common electrode face each other through the base body, a fourth capacitor portion is formed. When the second common electrode and the third common electrode face each other through the base body, a fifth capacitor portion may be formed. In this case, four capacitor portions connected in series can be formed with one base body.

[0015] When viewed from the first direction in which a pair of main surfaces face each other, the inner peripheral portions of the first electrode, the second electrode, the first common electrode, the second common electrode, and the third common electrode form a predetermined angle. The angles of the first electrode and the second electrode are approximately 90°, and the angles of the first common electrode, the second common electrode, and the third common electrode may be approximately 180°. In this case, the capacitances of the four capacitor portions can be made substantially equal. Therefore, it is possible to suppress variations in the voltage resistance of each capacitor portion.

[0016] The first electrode, the second electrode, and the third common electrode may be provided on one main surface, and the first common electrode and the second common electrode may be provided on the other main surface. Thereby, a structure can be obtained in which both lead terminals are arranged on one main surface side. Therefore, the shapes and lengths of the lead terminals can be made the same.

[0017] An exterior resin may be disposed between the first electrode and the second electrode. In this case, it is possible to suppress a short circuit or the like between the first electrode and the second voltage, and improve the voltage resistance of the capacitor.

[0018] The member electrically connected to the first electrode via solder may be only the first lead terminal. That is, no resistor or the like is connected to the first electrode. In this case, generation of the stray capacitance between the first electrode and the second electrode can be suppressed, and a capacitor section connected in series can be configured.

[0019] The facing areas of the electrodes and the common electrode in the plurality of capacitor sections may be substantially equal to each other. In this case, the capacitances in each capacitor section can be made substantially equal, and by making the voltages applied to each capacitor section substantially equal, short-circuit failures or the like in any of the capacitor sections can be suppressed, and breakdown can be suppressed.

Advantages of the Invention

[0020] According to the present invention, a capacitor capable of improving the resistance to voltage can be provided.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, and redundant descriptions will be omitted.

[0023] With reference to FIGS. 1 and 2, the configuration of the single-plate capacitor 1 according to this embodiment will be described. FIG. 1 is a front view showing the single-plate capacitor according to this embodiment. FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. 1. The single-plate capacitor 1 (capacitor) is an electronic component that can be mounted on a circuit board. The single-plate capacitor 1 is a capacitor component using a single plate-like element body 2. The single-plate capacitor 1 is a flat capacitor including dielectric ceramics and has a configuration different from that of a laminate in which internal electrodes are formed. For the sake of convenience of explanation, an XYZ coordinate system will be set for the explanation. The Y-axis direction is a direction perpendicular to the X-axis direction. The Z-axis direction is a direction perpendicular to the X-axis direction and the Y-axis direction. When a center line CL1 extending in the Y-axis direction is set, the shape of the single-plate capacitor 1 when viewed from the Z-axis direction has a shape symmetric about the center line CL1.

[0024] First, an example of the single-plate capacitor 1 in which two capacitor portions are connected in series will be described. As shown in FIGS. 1 and 2, the single-plate capacitor 1 includes an element body 2, a first electrode 3A, a second electrode 3B, a common electrode portion 4, a first lead terminal 6A, a second lead terminal 6B, and an exterior resin 7.

[0025] The element body 2 is composed of, for example, a dielectric element. The dielectric element is composed of, for example, a sintered body containing a dielectric material (such as dielectric ceramics of the BaTiO3 system, Ba(Ti,Zr)O3 system, or (Ba,Ca)TiO3 system). The overall shape of the element body 2 is in the shape of a disk or a flat cylinder. The element body 2 has a pair of circular main surfaces 2a (one main surface) and 2b (the other main surface) facing each other, and an outer peripheral surface 2c connecting the main surfaces 2a and 2b. The element body 2 has the facing direction of the main surfaces 2a and 2b in the Z-axis direction. The main surfaces 2a and 2b extend parallel to the XY plane. The main surface 2a is arranged on the positive side in the Z-axis direction, and the main surface 2b is arranged on the negative side in the Z-axis direction.

[0026] The first electrode 3A and the second electrode 3B are conductive layers provided on either main surface 2a, 2b of the base body 2. In the present embodiment, both the first electrode 3A and the second electrode 3B are provided on the main surface 2a. Further, the electrodes 3A, 3B are arranged so as to be separated from each other in the X-axis direction at the central position in the X-axis direction. The first electrode 3A is arranged on the positive side in the X-axis direction, and the second electrode 3B is arranged on the negative side in the X-axis direction. A gap GP1 is formed between the electrodes 3A, 3B. In the gap GP1, the main surface 2a of the base body 2 is exposed from the electrodes 3A, 3B. One of the electrodes 3A, 3B is a + electrode, and the other is a - electrode. The electrodes 3A, 3B are constituted by a sintered layer of an electrode paste containing metal or glass. As the metal, for example, Cu, Ni, Ag, etc. can be used.

[0027] The common electrode portion 4 shown in FIG. 2 is a conductive layer provided on either main surface 2a, 2b of the base body 2. The common electrode portion 4 is constituted by a combination of one or a plurality of common electrodes 10. The common electrode 10 forms a capacitor portion by facing other electrodes and is an electrode for connecting the capacitor portions in series. In the present embodiment, the common electrode portion 4 is constituted by one common electrode 10A provided on the main surface 2b. As the material of the common electrode 10A, the same material as that of the electrodes 3A, 3B may be adopted.

[0028] The first lead terminal 6A and the second lead terminal 6B shown in FIG. 1 are electrically connected to the electrodes 3A and 3B, respectively. The lead terminal connected to the + electrode is the + terminal, and the lead terminal connected to the - electrode is the - terminal. The first lead terminal 6A is connected to the first electrode 3A, and the second lead terminal 6B is connected to the second electrode 3B. For the connection between the lead terminals 6A and 6B and the electrode portion 3, a bonding material such as solder can be used. Examples of the constituent materials of the lead terminals 6A and 6B include phosphor bronze, stainless steel, Ni-Fe alloy (such as 42 alloy), etc. A metal plating layer such as a Ni plating layer or a Sn plating layer may be provided on the surfaces of the lead terminals 6A and 6B. The plating layer may be either a single layer or a multilayer.

[0029] The exterior resin 7 shown in FIGS. 1 and 2 is a member that protects the main parts such as the body 2. The exterior resin 7 is provided so as to cover the body 2 and the base end portions of the lead terminals 6A and 6B. The exterior resin 7 is composed of, for example, a resin material having insulating properties. Examples of the resin material constituting the exterior resin 7 include epoxy resin, silica, etc. The exterior resin 7 is formed, for example, by the dip method or injection molding using a mold. The exterior resin 7 generally has a shape corresponding to the shapes of the body 2, the electrodes 3A and 3B, and the lead terminals 6A and 6B. The exterior resin 7 may be in close contact with the surfaces of the body 2, the electrodes 3A and 3B, and the lead terminals 6A and 6B on the inner peripheral side. Therefore, as shown in FIG. 2, the material of the exterior resin 7 enters the gap GP1 between the electrodes 3A and 3B so as to be in close contact with the main surface 2a, and the exterior resin 7 is configured to be interposed between the electrodes 3A and 3B.

[0030] Next, referring to FIG. 3, the configuration of the single-layer capacitor 1 will be described in more detail. FIG. 3 is a diagram showing the structure of the electrodes and the common electrode. FIG. 3(a) is a view of the single-layer capacitor 1 with the exterior resin 7 omitted, seen from the positive side to the negative side in the Z-axis direction. FIG. 3(b) is a view of the single-layer capacitor 1 with the exterior resin 7 and the lead terminals 6A, 6B omitted, seen from the negative side to the positive side in the Y-axis direction. FIG. 3(c) is a view of the electrode on the main surface 2b side of the dielectric body 2, seen from the positive side to the negative side in the Z-axis direction. In FIG. 3(c), the main surface 2b of the dielectric body 2 is shown by a virtual line. In FIGS. 3(a) and (c), the center point CP of the dielectric body 2 when viewed from the Z-axis direction is shown.

[0031] As shown in FIG. 3(a), the electrodes 3A, 3B are provided so as to cover substantially the entire region of the main surface 2a of the dielectric body 2 other than the gap GP1. Therefore, the edge portions on the outer peripheral side of the electrodes 3A, 3B reach the boundary portion between the main surface 2a and the outer peripheral surface 2c. The common electrode 10A is provided so as to cover substantially the entire main surface 2b. Therefore, the edge portions on the outer peripheral side of the common electrode 10A reach the boundary portion between the main surface 2b and the outer peripheral surface 2c. In FIG. 3(c), in order to show that the main surface 2b does not overlap with the outer peripheral edge of the common electrode 10A, it is shown slightly larger than the common electrode 10A. The same applies to the subsequent figures.

[0032] The electrodes 3A, 3B each have edge portions 3Aa, 3Ba extending radially from the center point CP side. In the present embodiment, the edge portions 3Aa, 3Ba of the electrodes 3A, 3B extend linearly so as to be parallel to the center line CL1, respectively. Therefore, the gap GP1 between the electrodes 3A, 3B extends linearly in the Y-axis direction so as to be parallel to the center line CL1. Also, the width of the gap GP1, that is, the distance between the electrodes 3A, 3B, is substantially equal at each position in the Y-axis direction.

[0033] Here, when viewed from the Z-axis direction (the first direction) in which the main surfaces 2a and 2b face each other, the inner peripheral portions of the electrodes 3A and 3B form predetermined angles θ1 and θ2. Note that the inner peripheral portions of the electrodes 3A and 3B are the portions of the edges 3Aa and 3Ba of the electrodes 3A and 3B that are closest to the center point CP. Note that the inner peripheral portions of each of the subsequent common electrodes 10 are the same portions. In the present embodiment, the angles θ1 and θ2 of the electrodes 3A and 3B are approximately 180°. Note that when referred to as "approximately XX°" in this specification, it means an angle within the range including XX° and allowing for a deviation due to manufacturing error (for example, ± several degrees) from the XX°.

[0034] The members electrically connected to the first electrode 3A via solder are only the first lead terminals 6A. The members electrically connected to the second electrode 3B via solder are only the second lead terminals 6B. That is, no other electronic components such as resistors or conductor members are connected to the electrodes 3A and 3B via solder. The tip portions 6a on the connection sides of the lead terminals 6A and 6B do not protrude from the electrodes 3A and 3B when viewed from the Z-axis direction. That is, the tip portions 6a of the lead terminals 6A and 6B are connected to the electrodes 3A and 3B by solder and are not connected to other conductive members. The lead terminals 6A and 6B are drawn out from the electrodes 3A and 3B in a state where they spread so that the distance between them increases. Specifically, the first lead terminal 6A extends in a state inclined so as to go toward the positive side in the X-axis direction as it goes toward the negative side in the Y-axis direction. The second lead terminal 6B extends in a state inclined so as to go toward the negative side in the X-axis direction as it goes toward the negative side in the Y-axis direction. However, the drawing directions and shapes of the lead terminals 6A and 6B are not particularly limited. Note that since both the electrodes 3A and 3B are provided on the main surface 2a, the lead terminals 6A and 6B are both provided on the main surface 2a side. Therefore, compared with the case where the lead terminals 6A and 6B are provided on each of the main surfaces 2a and 2b, the shapes, lengths, etc. of the lead terminals 6A and 6B can be made the same. Also, the size of the single-layer capacitor 1 in the Z-axis direction can be reduced.

[0035] Next, the size of the single-layer capacitor 1 will be described. The thickness of the dielectric body 2 (dimension in the Z-axis direction) may be 1.0 mm or less, and preferably 0.6 mm or less. By setting it within such a range, the breakdown electric field strength of the single-layer capacitor 1 can be increased. The breakdown electric field strength is the value obtained by dividing the applied voltage at which the single-layer capacitor 1 breaks down by the thickness of the dielectric (dielectric body 2). Note that the lower limit value of the thickness of the dielectric body 2 is not particularly limited, and for example, it may be 0.1 mm or more. By setting it within such a range, the breakdown electric field strength can be increased within the range where the single-layer capacitor can be manufactured. The diameter of the dielectric body 2 may be 7 mm or more, and preferably 10 mm or more. By setting it within such a range, even when the single-layer capacitor 1 is divided into a plurality of capacitor portions, the capacitance can be ensured. The upper limit value of the diameter of the dielectric body 2 is not particularly limited, and it may be 20 mm or less. By setting it within such a range, it is possible to suppress the single-layer capacitor 1 from becoming too large and affecting the mounting. The distance between the electrodes in the gap GP1 may be 0.5 mm or more, and preferably 1 mm or more. By setting it within such a range, the insulation between the electrodes can be more reliably ensured. Note that the upper limit value of the distance between the electrodes is not particularly limited, and it may be 2 mm or less. By setting it within such a range, it is possible to suppress an increase in the portion that does not contribute to the capacitance. The relative permittivity of the dielectric body 2 is not particularly limited, and any general dielectric used for ceramic capacitors may be used (for example, 10 or more). Note that the thicknesses of the electrodes 3A, 3B, and the common electrode 10A are not particularly limited, and may be set, for example, to 0.1 μm or more and 10 μm or less.

[0036] As described above, between the electrodes 3A and 3B, there is no member such as a resistor or a conductor member that electrically connects the two. The exterior resin 7 is disposed in substantially the entire gap GP1 between the first electrode 3A and the second electrode 3B (see FIG. 2). Thus, the first electrode 3A and the second electrode 3B are insulated from each other on the surface of the dielectric body 2 (main surfaces 2a, 2b, and outer peripheral surface 2c). In the present embodiment, the first electrode 3A and the second electrode 3B are insulated from each other on the main surface 2a.

[0037] With the above configuration, the first electrode 3A and the common electrode 10A face each other in the Z-axis direction via the element body 2, thereby forming the first capacitor portion 21. The second electrode 3B and the common electrode 10A face each other via the element body 2, thereby forming the second capacitor portion 22. Here, among the common electrodes 10A, the portion facing the gap GP1 functions as a connection portion 31 that electrically connects the first capacitor portion 21 and the second capacitor portion 22. Therefore, the first capacitor portion 21 and the second capacitor portion 22 are connected in series via the connection portion 31 of the common electrode 10A.

[0038] Here, in the present embodiment, when viewed from the Z-axis direction, the area of the first electrode 3A and the area of the second electrode 3B are substantially equal. Therefore, the facing areas of the electrodes 3A and 3B and the common electrode 10A in the two capacitor portions 21 and 22 are substantially equal to each other.

[0039] The flow of current will be described. The current introduced into the first electrode 3A via the lead terminal 6A passes through the first capacitor portion 21 and flows to the common electrode 10A (FA1 in FIG. 3(b)). The current flows in the common electrode 10A from the first capacitor portion 21 side to the second capacitor portion 22 side via the connection portion 31 (FA2 in FIGS. 3(b) and (c)). The current passes through the second capacitor portion 22 and is introduced into the second electrode 3B (FA3 in FIG. 3(b)) and flows to the lead terminal 6B.

[0040] Next, the operation and effects of the single-plate capacitor 1 according to the present embodiment will be described.

[0041] Here, the breakdown voltage resistance of the single-layer capacitor 1 will be described. The breakdown voltage resistance is a parameter for evaluating the height of the voltage when a voltage is applied until the product is broken. In a ceramic capacitor, the value obtained by dividing the applied voltage at breakdown by the dielectric thickness (breakdown electric field strength) has the property of increasing as the dielectric thickness becomes thinner. When capacitors are connected in series and a voltage is applied, the voltage is applied separately to each capacitor. The voltage applied to each capacitor is proportional to the reciprocal of the capacitance of each capacitor. For example, if two capacitors have the same capacitance, the voltage becomes 1 / 2 when connected in series. Considering a capacitor (a composite of capacitors) with a reduced dielectric thickness and an increased number of series connections, the breakdown voltage resistance of each capacitor decreases as the dielectric becomes thinner, but by adopting a series structure, the applied voltage decreases according to the number of series connections. And, as described above, the breakdown electric field strength increases as the dielectric thickness becomes thinner. Therefore, considering the increase and decrease of the applied voltage and the increase of the breakdown electric field strength due to thinning, the breakdown voltage resistance of the entire structure of a series-structured capacitor may be improved.

[0042] The single-layer capacitor 1 according to this embodiment includes a first lead terminal 6A connected to the first electrode 3A and a second lead terminal 6B connected to the second electrode 3B. Therefore, the single-layer capacitor 1 can be mounted on a circuit board by the lead terminals 6A and 6B. In addition to these first electrode 3A and second electrode 3B, the single-layer capacitor 1 includes a common electrode portion 4. The first capacitor portion 21 is formed by the first electrode 3A and the common electrode portion 4 facing each other with the element body 2 interposed therebetween. Also, the second capacitor portion 22 is formed by the second electrode 3B and the common electrode portion 4 facing each other with the element body 2 interposed therebetween. These first capacitor portion 21 and second capacitor portion 22 are connected in series. On the other hand, since the first electrode 3A and the second electrode 3B are insulated from each other on the surface of the element body 2, the flow of current between the two can be suppressed. Therefore, the current flowing between the first electrode 3A and the second electrode 3B to which the lead terminals 6A and 6B are connected can flow through the first capacitor portion 21 and the second capacitor portion 22 without flowing directly between the electrodes. In this way, a plurality of capacitor portions 21 and 22 connected in series can be formed in one element body 2. Since the voltage applied to each capacitor portion 21 and 22 can be lowered, the resistance of the single-layer capacitor 1 to voltage can be improved. From the above, the resistance of the single-layer capacitor 1 to voltage can be improved. Also, as described above, by increasing the number of capacitor portions connected in series and reducing the thickness of the element body 2, the resistance to voltage can be further improved.

[0043] The first electrode 3A and the second electrode 3B are provided on one main surface 2a, the common electrode portion 4 is provided on the other main surface 2b, has a common electrode 10A facing the first electrode 3A and the second electrode 3B, and the first capacitor portion 21 and the second capacitor portion 22 are connected in series via the common electrode 10A, and the first electrode 3A and the second electrode 3B may be insulated from each other on one main surface 2a. In this way, two capacitor portions 21 and 22 directly connected by one element body 2 can be formed.

[0044] An exterior resin 7 may be disposed between the first electrode 3A and the second electrode 3B. In this case, a short circuit or the like between the first electrode 3A and the second electrode 3B can be suppressed, and the resistance of the single-plate capacitor 1 to voltage can be improved.

[0045] The member electrically connected to the first electrode 3A via solder may be only the first lead terminal 6A. That is, no resistor or the like is connected to the first electrode 3A. In this case, the generation of stray capacitance between the first electrode 3A and the second electrode 3B can be suppressed, and the capacitor units 21 and 22 connected in series can be formed.

[0046] The facing areas between the electrodes 3A and 3B and the common electrode 10A in the plurality of capacitor units 21 and 22 may be substantially equal to each other. In this case, the capacitance in each capacitor unit 21 and 22 can be made substantially equal, and by making the voltages applied to the capacitor units 21 and 22 substantially equal, a short circuit failure or the like in any of the capacitor units 21 and 22 can be suppressed, and destruction can be suppressed. For example, when the difference in capacitance between a plurality of capacitors is large, the variation in voltage may become large.

[0047] The present invention is not limited to the above-described embodiments.

[0048] For example, the single-plate capacitor 1 according to the above-described embodiment had a series connection structure of two capacitor units. Instead of this, the single-plate capacitor 1 may have a series connection structure of three or more capacitor units. That is, the common electrode portion 4 may have a plurality of common electrodes 10, and the plurality of common electrodes 10 may face each other via the element body 2. In this case, by using the plurality of common electrodes 10, three or more capacitor units can be formed. In the description of the following modification examples, the description of the parts common to the single-plate capacitor 1 according to the foregoing embodiment is omitted, but the same operations and effects can be obtained for the common configurations.

[0049] For example, the structure of the single-plate capacitor 1 shown in FIG. 4 may be adopted. The common electrode portion 4 has a first common electrode 10B and a second common electrode 10C. The first electrode 3A and the first common electrode 10B face each other with the element body 2 therebetween, thereby forming the first capacitor portion 21. The second electrode 3B and the second common electrode 10C face each other with the element body 2 therebetween, thereby forming the second capacitor portion 22. The first common electrode 10B and the second common electrode 10C face each other with the element body 2 therebetween, thereby forming the third capacitor portion 23. In this case, three capacitor portions 21, 22, and 23 connected in series can be formed with one element body 2.

[0050] The first electrode 3A and the second common electrode 10C are provided on one main surface 2a (see FIGS. 4(a) and 4(b)), and the second electrode 3B and the first common electrode 10B are provided on the other main surface 2b (see FIGS. 4(b) and 4(c)). In this case, the first lead terminal 6A is disposed on the side of the one main surface 2a, and the second lead terminal 6B is disposed on the side of the other main surface 2b. Thereby, a structure can be adopted in which the element body 2 is sandwiched by the lead terminals 6A and 6B. Therefore, the thickness of the exterior resin 7 on each of the main surfaces 2a and 2b can be made uniform.

[0051] The shape of the second common electrode 10C on the main surface 2a is the same as the shape of the second electrode 3B shown in FIG. 3(a). As shown in FIG. 4(a), the second common electrode 10C has an edge portion 10Ca extending in the radial direction from the center point CP side. In the present embodiment, the edge portion 10Ca extends linearly so as to be parallel to CL1. Therefore, the gap GP2 between the electrodes 3A and 10C extends linearly in the Y-axis direction so as to be parallel to the center line CL1. Further, the width of the gap GP2, that is, the distance between the electrodes 3A and 10C, is substantially equal at each position in the Y-axis direction.

[0052] As shown in FIG. 4(c), a reference line SL1 extending from the center point CP to the negative side in the X-axis direction with respect to the main surface 2b is set. At this time, the gap GP3 between the second electrode 3B and the first common electrode 10B has an L-shaped configuration. The gap GP3 has a portion extending from the center point CP along the reference line SL1 to the negative side in the X-axis direction and a portion extending from the center point CP along the center line CL1 to the negative side in the Y-axis direction. The second electrode 3B and the first common electrode 10B have edge portions 3Ba, 10Ba extending radially from the center point CP side. In the present embodiment, the edge portions 3Ba, 10Ba extend in an L-shape so as to be parallel to the reference line SL1 and the center line CL1 in each portion. Therefore, the gap GP3 between the electrodes 3B, 10B linearly extends in the X-axis direction and the Y-axis direction so as to be parallel to the reference line SL1 and the center line CL1 in each portion. Also, the width of the gap GP3, that is, the distance between the electrodes 3B, 10B, is substantially equal at each position.

[0053] As shown in FIGS. 4(a) and (c), when viewed from the Z-axis direction (first direction) in which the main surfaces 2a and 2b face each other, the inner peripheral side portions of the electrodes 3A, 3B, the first common electrode 10B, and the second common electrode 10C form predetermined angles θ1, θ2, θ3, θ4. The angles θ1, θ4 of the first electrode 3A and the second common electrode 10C are approximately 180°. The angle θ3 of the first common electrode is approximately 270°. The angle θ2 of the second electrode 3B is approximately 90°.

[0054] As shown in FIG. 4(c), a portion of the first common electrode 10B that faces the gap GP2 functions as a connection portion 32 that electrically connects the first capacitor portion 21 and the third capacitor portion 23. Therefore, the first capacitor portion 21 and the third capacitor portion 23 are connected in series via the connection portion 32 of the common electrode 10B. As shown in FIG. 4(a), a portion of the common electrode 10C that faces the gap GP3 functions as a connection portion 33 that electrically connects the second capacitor portion 22 and the third capacitor portion 23. Therefore, the second capacitor portion 22 and the third capacitor portion 23 are connected in series via the connection portion 33 of the common electrode 10C.

[0055] The flow of current will be described. The current introduced into the first electrode 3A via the lead terminal 6A passes through the first capacitor section 21 and flows to the first common electrode 10B (FB1 in FIG. 4(b)). The current flows in the first common electrode 10B from the first capacitor section 21 side to the third capacitor section 23 side via the connection section 32 (FB2 in FIGS. 4(b) and (c)). The current passes through the third capacitor section 23 and flows to the second common electrode 10C (FB3 in FIG. 4(b)). The current flows in the second common electrode 10C from the third capacitor section 23 side to the second capacitor section 22 side via the connection section 33 (FB4 in FIG. 4(a)). The current passes through the capacitor section 22 and is introduced into the second electrode 3B (FC5 in FIG. 4(b)) and flows to the lead terminal 6B.

[0056] Also, as the series connection structure of the three capacitor sections 21, 22, and 23, the form shown in FIG. 5 may be adopted.

[0057] As shown in FIG. 5(a), a reference line SL2 is set that extends so as to be inclined toward the positive side in the Y-axis direction as it goes toward the positive side in the X-axis direction from the center point CP with respect to the main surface 2a. At this time, the gap GP2 between the first electrode 3A and the second common electrode 10C has a V-shaped configuration. The gap GP2 has a portion that extends so as to be inclined toward the positive side in the X-axis direction along the reference line SL2 from the center point CP, and a portion that extends toward the negative side in the Y-axis direction along the center line CL1 from the center point CP. The first electrode 3A and the second common electrode 10C have edge portions 3Aa and 10Ca that extend radially from the center point CP side. In the present embodiment, the edge portions 3Aa and 10Ca extend in a V-shape so as to be parallel to the reference line SL2 and the center line CL1 in each portion. Therefore, the gap GP2 between the electrodes 3A and 10C extends linearly in a direction inclined with respect to the X-axis direction and in the Y-axis direction so as to be parallel to the reference line SL2 and the center line CL1 in each portion. Also, the width of the gap GP2, that is, the distance between the electrodes 3A and 10C, is substantially equal at each position.

[0058] As shown in FIG. 5(c), a reference line SL1 is set to extend on the main surface 2b so as to incline toward the positive side in the Y-axis direction as it goes toward the negative side in the X-axis direction from the center point CP with respect to the main surface 2b. At this time, the gap GP3 between the second electrode 3B and the first common electrode 10B has a V-shaped configuration. The gap GP3 has a portion extending from the center point CP so as to incline toward the negative side in the X-axis direction along the reference line SL1, and a portion extending from the center point CP toward the negative side in the Y-axis direction along the center line CL1. The second electrode 3B and the first common electrode 10B have edge portions 3Ba and 10Ba extending radially from the center point CP side. In the present embodiment, the edge portions 3Ba and 10Ba extend in a V shape so as to be parallel to the reference line SL1 and the center line CL1 in each portion. Therefore, the gap GP3 between the electrodes 3B and 10B linearly extends in a direction inclined with respect to the X-axis direction and in the Y-axis direction so as to be parallel to the reference line SL1 and the center line CL1 in each portion. Further, the width of the gap GP3, that is, the distance between the electrodes 3B and 10B is substantially equal at each position.

[0059] As shown in FIGS. 5(a) and 5(c), when viewed from the Z-axis direction (first direction) in which the main surfaces 2a and 2b face each other, the inner peripheral side portions of the electrodes 3A and 3B, the first common electrode 10B, and the second common electrode 10C form predetermined angles θ1, θ2, θ3, and θ4. The angles θ1 and θ2 of the first electrode 3A and the second electrode 3B are approximately 120°. The angles θ3 and θ4 of the first common electrode 10B and the second common electrode 10C are approximately 240°.

[0060] In the present embodiment, the facing areas between the electrodes 3A and 3B and the common electrodes 10B and 10C in the plurality of capacitor portions 21, 22, and 23 are substantially equal to each other. In this case, the electrostatic capacitances in the respective capacitor portions 21, 22, and 23 can be made substantially equal, and by making the voltages applied to the respective capacitor portions 21, 22, and 23 substantially equal, short-circuit failures and the like in any of the capacitor portions 21, 22, and 23 can be suppressed, and destruction can be suppressed.

[0061] Note that the other structures of the configuration in FIG. 5 and the flow of current are the same as those of the configuration in FIG. 4.

[0062] Furthermore, a single-plate capacitor 1 shown in FIG. 6 may be adopted. The common electrode portion 4 has a first common electrode 10B, a second common electrode 10C, and a third common electrode 10D. The first electrode 3A and the first common electrode 10B face each other with the element body 2 therebetween, thereby forming a first capacitor portion 21. The second electrode 3B and the second common electrode 10C face each other with the element body 2 therebetween, thereby forming a second capacitor portion 22. The first common electrode 10B and the third common electrode 10D face each other with the element body 2 therebetween, thereby forming a fourth capacitor portion 24. The second common electrode 10C and the third common electrode 10D face each other with the element body 2 therebetween, thereby forming a fifth capacitor portion 25. In this case, four capacitor portions connected in series can be formed with one element body 2.

[0063] The first electrode 3A, the second electrode 3B, and the third common electrode 10D are provided on one main surface 2a, and the first common electrode 10B and the second common electrode 10C are provided on the other main surface 2b. Thereby, a structure can be adopted in which both lead terminals 6A and 6B are arranged on the side of the one main surface 2a. Therefore, the shapes, lengths, etc. of the lead terminals 6A and 6B can be made the same.

[0064] As shown in Fig. 6(a), a reference line SL3 extending in the X-axis direction from the center point CP is set with respect to the main surface 2a. At this time, the gap GP4 between the third common electrode 10D and the electrodes 3A and 3B has a shape that linearly extends in the X-axis direction. The third common electrode 10D has an edge 10Da extending radially from the center line side. The gap GP1 between the electrodes 3A and 3B has a shape that linearly extends in the negative side in the X-axis direction from the center point CP. In the present embodiment, the edges 3Aa and 3Ba of the electrodes 3A and 3B have an L-shaped shape having a portion that linearly extends so as to be parallel to the center line CL1 and a portion that linearly extends so as to be parallel to the reference line SL3. The edge 10Da of the third common electrode 10D linearly extends so as to be parallel to the reference line SL3. Therefore, the gap GP1 between the electrodes 3A and 3B linearly extends in the Y-axis direction so as to be parallel to the center line CL1. Also, the width of the gap GP1, that is, the distance between the electrodes 3A and 3B, is substantially equal at each position in the Y-axis direction. The gap GP4 between the electrodes 3A and 3B and the third common electrode 10D linearly extends in the X-axis direction so as to be parallel to the reference line SL3. Also, the width of the gap GP4, that is, the distance between the electrodes 3A and 3B and the third common electrode 10D, is substantially equal at each position in the X-axis direction.

[0065] As shown in Fig. 6(c), on the main surface 2b, the first common electrode 10B and the second common electrode 10C each have an edge 10Ba and 10Ca extending radially from the center point CP side. In the present embodiment, the edges 10Ba and 10Ca of the common electrodes 10B and 10C linearly extend so as to be parallel to the center line CL1, respectively. Therefore, the gap GP5 between the common electrodes 10B and 10C linearly extends in the Y-axis direction so as to be parallel to the center line CL1. Also, the width of the gap GP5, that is, the distance between the common electrodes 10B and 10C, is substantially equal at each position in the Y-axis direction.

[0066] As shown in FIGS. 6(a) and 6(c), when viewed from the Z-axis direction (the first direction) in which the main surfaces 2a and 2b face each other, the inner peripheral portions of the first electrode 3A, the second electrode 3B, the first common electrode 10B, the second common electrode 10C, and the third common electrode 10D form predetermined angles θ1, θ2, θ3, θ4, and θ5. The angles θ1 and θ2 of the first electrode 3A and the second electrode 3B are approximately 90°, and the angles θ3, θ4, and θ5 of the first common electrode 10B, the second common electrode 10C, and the third common electrode 10D may be approximately 180°. In this case, the capacitances of the four capacitor portions 21, 22, 24, and 25 can be made substantially equal. Therefore, it is possible to suppress variations in the voltage resistance of each capacitor portion.

[0067] As shown in FIG. 6(c), a portion of the first common electrode 10B that faces the gap GP4 functions as a connection portion 34 that electrically connects the first capacitor portion 21 and the fourth capacitor portion 24. Therefore, the first capacitor portion 21 and the fourth capacitor portion 24 are connected in series via the connection portion 34 of the first common electrode 10B. A portion of the second common electrode 10C that faces the gap GP4 functions as a connection portion 35 that electrically connects the second capacitor portion 22 and the fifth capacitor portion 25. Therefore, the second capacitor portion 22 and the fifth capacitor portion 25 are connected in series via the connection portion 35 of the second common electrode 10C. As shown in FIG. 6(a), a portion of the third common electrode 10D that faces the gap GP5 functions as a connection portion 36 that electrically connects the fourth capacitor portion 24 and the fifth capacitor portion 25. Therefore, the fourth capacitor portion 24 and the fifth capacitor portion 25 are connected in series via the connection portion 36 of the third common electrode 10D.

[0068] The flow of current will be described. The current introduced to the first electrode 3A via the lead terminal 6A passes through the first capacitor section 21 and flows to the first common electrode 10B (FC1 in FIG. 6(b)). The current flows from the first capacitor section 21 side to the fourth capacitor section 24 side within the first common electrode 10B via the connection portion 34 (FC2 in FIG. 6(c)). The current passes through the fourth capacitor section 24 and flows to the third common electrode 10D (FC3 in FIG. 4(b)). The current flows from the fourth capacitor section 24 side to the fifth capacitor section 25 side within the third common electrode 10D via the connection portion 36 (FC4 in FIG. 6(a)). The current passes through the capacitor section 25 and flows to the second common electrode 10C (FC5 in FIG. 6(b)). The current flows from the fifth capacitor section 25 side to the second capacitor section 22 side within the second common electrode 10C via the connection portion 35 (FC6 in FIG. 6(c)). The current passes through the capacitor section 22 and is introduced to the second electrode 3B (FC7 in FIG. 6(b)) and flows to the lead terminal 6B.

[0069] The facing areas between the electrodes 3A, 3B and the common electrodes 10B, 10C, 10D in the plurality of capacitor sections 21, 22, 24, 25 may be substantially equal to each other. In this case, the capacitances in each of the capacitor sections 21, 22, 24, 25 can be made substantially equal, and by making the voltages applied to each of the capacitor sections 21, 22, 24, 25 substantially equal, short-circuit failures and the like in any of the capacitor sections 21, 22, 24, 25 can be suppressed, and breakdown can be suppressed.

[0070] Next, with reference to FIG. 8, the evaluation results and simulation results of the examples and comparative examples will be described. As Comparative Example 1, the single-plate capacitor 200 shown in FIG. 7 was adopted. The single-plate capacitor 200 according to Comparative Example 1 has a first electrode 3A and a second electrode 3B that cover the front surfaces of both sides of the dielectric body 2. The single-plate capacitor 200 has one capacitor section. The diameter and thickness of the dielectric body 2 were set to the values shown in FIG. 8. As Examples 1 and 2, a single-plate capacitor having a structure in which two capacitor sections are connected in series as shown in FIG. 3 was adopted. As Examples 3 and 4, a single-plate capacitor having a structure in which three capacitor sections are connected in series as shown in FIG. 5 was adopted. As Examples 5 and 6, a single-plate capacitor having a structure in which four capacitor sections are connected in series as shown in FIG. 6 was adopted. Note that Examples 1, 3, and 5 have the same diameter as Comparative Example 1, and Examples 2, 4, and 6 have a larger diameter of the dielectric body than Comparative Example 1. Also, as the number of capacitors connected in series increases, the thickness of the dielectric body was made thinner so as to be in an inverse proportional relationship with the increase ratio of the number of series connections.

[0071] The "breakdown voltage ratio" and "capacitance ratio" were measured for Comparative Example 1 and each example. The "breakdown voltage characteristic" is a parameter for evaluating the height of the voltage when a voltage is applied until the product is broken. Note that the "breakdown voltage ratio" and "capacitance ratio" of Examples 1 to 6 indicate the ratios when the value of Comparative Example 1 is set to "1". Also, as the measurement methods for the breakdown voltage ratio, the measurement method called "AC-Vb" and the measurement method called "impulse withstand voltage" were adopted. "AC-Vb" is a measurement method in which the voltage applied to the sample is increased with 50 Hz alternating current, and the voltage at the time of breakdown is recorded. "Impulse withstand voltage" is a measurement method in which the voltage is increased according to the conditions described in "JIS C504-14:2014", and the voltage at the time of breakdown is recorded. As shown in FIG. 8, it was confirmed that by increasing the number of series connections and making the thickness of the dielectric body thinner (0.6 mm or less), the breakdown voltage ratio can be improved more than the voltage withstand dispersion effect due to series connection in both "AC-Vb" and "impulse withstand voltage". Also, regarding the capacitance ratio, from the results of Examples 2, 4, and 6, it was confirmed that by increasing the diameter of the dielectric body (10 mm or more), in combination with the effect of making the thickness thinner, a capacitance ratio equivalent to that of Comparative Example 1 can be obtained.

[0072] The present invention is not limited to the above-described embodiments.

[0073] The configurations of the above-described embodiments and modified examples are merely examples and can be appropriately changed within the scope of the gist of the present invention. For example, although those with four in series are exemplified, even more in series may be adopted.

[0074] [Embodiment 1] A base body having a pair of main surfaces facing each other, A first electrode, a second electrode, and a common electrode portion provided on any one of the main surfaces of the base body, A first lead terminal connected to the first electrode by soldering, A second lead terminal connected to the second electrode by soldering, The first capacitor portion is formed by the first electrode and the common electrode portion facing each other through the base body, The second capacitor portion is formed by the second electrode and the common electrode portion facing each other through the base body, The first capacitor portion and the second capacitor portion are connected in series, The first electrode and the second electrode are insulated from each other on the surface of the base body, capacitor. [Embodiment 2] The first electrode and the second electrode are provided on one of the main surfaces, The common electrode portion is provided on the other main surface and has a common electrode facing the first electrode and the second electrode, The first capacitor portion and the second capacitor portion are connected in series through the common electrode, The first electrode and the second electrode are insulated from each other on the one main surface, the capacitor according to Embodiment 1. [Embodiment 3] The common electrode portion has a plurality of common electrodes, and the plurality of common electrodes face each other through the base body, the capacitor according to Embodiment 1 or 2. [Embodiment 4] The common electrode portion has a first common electrode and a second common electrode, The first capacitor portion is formed by the first electrode and the first common electrode facing each other through the element body, The second capacitor portion is formed by the second electrode and the second common electrode facing each other through the element body, The capacitor according to Form 3, wherein a third capacitor portion is formed by the first common electrode and the second common electrode facing each other through the element body. [Form 5] When viewed from the first direction in which the pair of main surfaces face each other, the inner peripheral side portions of the first electrode, the second electrode, the first common electrode, and the second common electrode form a predetermined angle, The angle of the first electrode and the second electrode is approximately 120°, The capacitor according to Form 4, wherein the angle of the first common electrode and the second common electrode is approximately 240°. [Form 6] The first electrode and the second common electrode are provided on one of the main surfaces, The capacitor according to Form 4 or 5, wherein the second electrode and the first common electrode are provided on the other main surface. [Form 7] The common electrode portion has a first common electrode, a second common electrode, and a third common electrode, The first capacitor portion is formed by the first electrode and the first common electrode facing each other through the element body, The second capacitor portion is formed by the second electrode and the second common electrode facing each other through the element body, The fourth capacitor portion is formed by the first common electrode and the third common electrode facing each other through the element body, The capacitor according to Form 3, wherein the fifth capacitor portion is formed by the second common electrode and the third common electrode facing each other through the element body. [Form 8] When viewed from the first direction in which the pair of main surfaces face each other, the inner peripheral portions of the first electrode, the second electrode, the first common electrode, the second common electrode, and the third common electrode form a predetermined angle. The angles of the first electrode and the second electrode are approximately 90°. The capacitor according to embodiment 7, wherein the angles of the first common electrode, the second common electrode, and the third common electrode are approximately 180°. [Embodiment 9] The first electrode, the second electrode, and the third common electrode are provided on one of the main surfaces. The capacitor according to embodiment 7 or 8, wherein the first common electrode and the second common electrode are provided on the other main surface. [Embodiment 10] The capacitor according to any one of embodiments 1 to 9, wherein an exterior resin is disposed between the first electrode and the second electrode. [Embodiment 11] The capacitor according to any one of embodiments 1 to 10, wherein the member electrically connected to the first electrode via solder is only the first lead terminal. [Embodiment 12] The capacitor according to any one of embodiments 1 to 11, wherein the facing areas between the electrodes and the common electrodes in a plurality of capacitor portions are substantially equal to each other.

Explanation of Reference Numerals

[0075] 1... single-plate capacitor (capacitor), 2... element body, 3A... first electrode, 3B... second electrode, 4... common electrode portion, 6A... first lead terminal, 6B... second lead terminal, 7... exterior resin, 10A... common electrode, 10B... first common electrode, 10C... second common electrode, 10D... third common electrode, 21... first capacitor portion, 22... second capacitor portion, 23... third capacitor portion, 24... fourth capacitor portion, 25... fifth capacitor portion.

Claims

1. A body having a pair of main surfaces facing each other, a first electrode, a second electrode, and a common electrode portion provided on any one of the main surfaces of the body, a first lead terminal connected to the first electrode by solder, a second lead terminal connected to the second electrode by solder, and a first capacitor portion is formed by the first electrode and the common electrode portion facing each other through the body, a second capacitor portion is formed by the second electrode and the common electrode portion facing each other through the body, the first capacitor portion and the second capacitor portion are connected in series, a capacitor, wherein the first electrode and the second electrode are insulated from each other on the surface of the body.

2. The first electrode and the second electrode are provided on one of the main surfaces, the common electrode portion is provided on the other main surface and has a common electrode facing the first electrode and the second electrode, the first capacitor portion and the second capacitor portion are connected in series through the common electrode, the capacitor according to claim 1, wherein the first electrode and the second electrode are insulated from each other on the one main surface.

3. The capacitor according to claim 1, wherein the common electrode portion has a plurality of common electrodes, and the plurality of common electrodes face each other through the body.

4. The common electrode portion has a first common electrode and a second common electrode, the first capacitor portion is formed by the first electrode and the first common electrode facing each other through the body, the second capacitor portion is formed by the second electrode and the second common electrode facing each other through the body, the capacitor according to claim 3, wherein a third capacitor portion is formed by the first common electrode and the second common electrode facing each other through the body.

5. When viewed from a first direction in which the pair of main surfaces face each other, the inner peripheral side portions of the first electrode, the second electrode, the first common electrode, and the second common electrode form a predetermined angle, the angle of the first electrode and the second electrode is approximately 120°, the capacitor according to claim 4, wherein the angle of the first common electrode and the second common electrode is approximately 240°.

6. The first electrode and the second common electrode are provided on one of the main surfaces, The capacitor according to claim 4, wherein the second electrode and the first common electrode are provided on the other main surface.

7. The common electrode portion has a first common electrode, a second common electrode, and a third common electrode. The first capacitor portion is formed by the first electrode and the first common electrode facing each other with the element body interposed therebetween. The second capacitor portion is formed by the second electrode and the second common electrode facing each other with the element body interposed therebetween. The fourth capacitor portion is formed by the first common electrode and the third common electrode facing each other with the element body interposed therebetween. The capacitor according to claim 3, wherein the fifth capacitor portion is formed by the second common electrode and the third common electrode facing each other with the element body interposed therebetween.

8. When viewed from the first direction in which the pair of main surfaces face each other, the inner peripheral portions of the first electrode, the second electrode, the first common electrode, the second common electrode, and the third common electrode form a predetermined angle. The angles of the first electrode and the second electrode are approximately 90°. The capacitor according to claim 7, wherein the angles of the first common electrode, the second common electrode, and the third common electrode are approximately 180°.

9. The first electrode, the second electrode, and the third common electrode are provided on one of the main surfaces. The capacitor according to claim 7, wherein the first common electrode and the second common electrode are provided on the other main surface.

10. The capacitor according to claim 1, wherein an exterior resin is disposed between the first electrode and the second electrode.

11. The capacitor according to claim 1, wherein the member electrically connected to the first electrode via solder is only the first lead terminal.

12. The capacitor according to any one of claims 1 to 11, wherein the facing areas between the electrodes and the common electrodes in the plurality of capacitor portions are substantially equal to each other.

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