JP5825935B2 - Capacitor - Google Patents

Description

  The present invention relates to a capacitor such as a chip capacitor and a leaded capacitor.

  A capacitor is known in which a dielectric filler made of inorganic particles is dispersed in a resin to form a dielectric film, which is applied to a dielectric layer (for example, Patent Documents 1 and 2). In such a capacitor, high capacity is realized by dispersing inorganic particles having a dielectric constant higher than that of the resin in the resin. In Patent Document 1, 0.3 μm to 0.5 μm is disclosed as the average particle diameter of the dielectric filler, and in Patent Document 2, 0.2 μm is disclosed as the average particle diameter of the dielectric filler.

JP 2006-225484 A JP 2008-229849 A

  In the dielectric film in which the inorganic particles are dispersed as described above, the dielectric constant of the inorganic particles is higher than the dielectric constant of the resin, so that the applied electric field tends to concentrate around the inorganic particles, thereby increasing the dielectric strength. descend.

  An object of the present invention is to provide a capacitor capable of improving the dielectric strength.

  A capacitor according to one embodiment of the present invention includes a pair of electrodes and a dielectric positioned between the pair of electrodes, and the dielectric includes a plurality of first inorganic particles having a particle size of 130 nm or less. Particles and a plurality of second inorganic particles having a particle size of 160 nm or more, and the second inorganic particles are connected to each other via a three-dimensional matrix structure formed by bonding the plurality of first inorganic particles to each other. Are connected.

  Preferably, at least one of the first inorganic particles and the second inorganic particles has a perovskite structure.

  Suitably, the said 1st inorganic particle and the said 2nd inorganic particle are couple | bonded through the 1st neck part.

  Preferably, the first neck portion is made of the same material as the first inorganic particles.

  Preferably, the first inorganic particles are bonded to each other via the second neck portion.

  Preferably, a resin is present between the first inorganic particles forming the three-dimensional matrix structure.

  Preferably, the second inorganic particles are not directly bonded to each other.

  Preferably, the width of the second neck portion is larger than the width of the first neck portion.

  Preferably, the first inorganic particles have a first dielectric constant, and the second inorganic particles have a second dielectric constant higher than the first dielectric constant.

  According to said structure, a dielectric strength can be improved.

FIG. 1A is a perspective view showing the appearance of a capacitor according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along the line Ib-Ib in FIG. 2A is an enlarged sectional view showing a region IIa in FIG. 1B, and FIG. 2B is an enlarged sectional view showing a region IIb in FIG. 3A to 3D are views for explaining a method of manufacturing the capacitor of FIG. FIG. 4A to FIG. 4C are diagrams showing a continuation of FIG. FIG. 5A and FIG. 5B are diagrams showing a continuation of FIG. The photograph which imaged the dielectric material concerning an example with the electron microscope. The photograph which expands and shows the area | region VII of FIG. The figure which shows the particle size distribution in the dielectric material which concerns on an Example.

  FIG. 1A is a perspective view showing an appearance of the capacitor 1 according to the embodiment of the present invention.

  The capacitor 1 is configured as a capacitor with leads, and includes a main body 3 and a pair of leads 4 that extend from the main body 3 and to which a voltage is applied. The main body 3 is formed in a substantially rectangular parallelepiped shape, for example, and the pair of leads 4 extends from one surface of the rectangular parallelepiped, for example. Although the magnitude | size of the main-body part 3 may be set suitably, for example, one side is 3-10 dozen millimeters.

  FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG.

  The main body 3 is configured as a multilayer capacitor, for example, and includes a plurality of dielectrics 5 and a plurality of internal electrodes 7 that are alternately stacked. The main body 3 has a pair of external electrodes 9 connected to the plurality of internal electrodes 7, and an exterior part 11 that covers the dielectric 5, the external electrodes 9, and the like.

  The plurality of dielectrics 5 and the plurality of internal electrodes 7 are laminated in an appropriate number according to the required capacity and the like. In FIG. 1, the internal electrodes 7 are stacked so as to have 8 layers, but the number of stacked layers is not limited to this, and may be, for example, 100 to 1000 layers.

  For example, the plurality of dielectrics 5 have the same shape and size. Each dielectric 5 is formed in a flat plate shape (film shape) having a substantially constant thickness. The thickness of the dielectric 5 may be appropriately set according to the applied voltage, the required capacity, and the like, and is, for example, 5 to 20 μm. The planar shape of the dielectric 5 may be set as appropriate, but is rectangular, for example.

  For example, the plurality of internal electrodes 7 have the same shape and size. Each internal electrode 7 is formed in a flat plate shape (film shape) having a substantially constant thickness. The planar shape of the internal electrode 7 may be set as appropriate, but is rectangular, for example. The plurality of internal electrodes 7 are alternately arranged in the stacking direction so as to be shifted from each other in the facing direction of the pair of external electrodes 9. The plurality of internal electrodes 7 are alternately connected to one or the other of the pair of external electrodes 9 in the stacking direction in one side (edge) of a planar rectangle. The internal electrode 7 is made of, for example, a metal such as Al or an Al—Zn alloy, or a mixed material containing these as a main component.

  The external electrode 9 is formed so as to cover the side surface of the multilayer body 8 constituted by the plurality of dielectrics 5 and the plurality of internal electrodes 7, and is formed of a metal such as Sn, Zn, or Sn—Zn alloy, for example. ing.

  The exterior portion 11 covers the entire laminate 8 and the pair of external electrodes 9 and constitutes the entire outer surface of the main body portion 3. The exterior part 11 is formed of an insulating material such as a resin. The resin is, for example, a thermosetting resin such as an epoxy resin, a polyimide resin, or a cyanoresin resin.

  The lead 4 is made of a metal plate or a wire, and has one end connected to the outer surface of the external electrode 9 and the other end extending from the exterior portion 11. The lead 4 is made of, for example, a metal such as Fe, Cu, or Sn.

  FIG. 2A is an enlarged cross-sectional view showing a region IIa in FIG. FIG. 2B is an enlarged cross-sectional view showing a region IIb in FIG.

  The dielectric 5 is composed of a plurality of inorganic particles (15, 17, etc.) bonded to each other and a resin 19 located in a gap between them.

  For example, the dielectric 5 includes 20% by volume or more and 80% or less by volume of inorganic particles, 20% by volume or more and 80% or less by volume of the resin 19, more preferably 50% by volume or more and 80% or less by volume of inorganic particles, 20% by volume or more and 50% by volume or less of the resin 19 (the volume ratio of the inorganic particles is equal to or higher than the volume ratio of the resin 19), more preferably 60% by volume or more and 70% or less by volume of the inorganic particles. It is contained in a volume of 40% by volume or more.

  The plurality of inorganic particles include a plurality of first inorganic particles 15 and a second inorganic particle 17 having a larger particle diameter than the plurality of first inorganic particles 15. The boundary between the particle size of the first inorganic particles 15 and the particle size of the second inorganic particles 17 is, for example, 150 nm.

  The particle diameter of the first inorganic particles 15 is 130 nm or less. In this case, preferably, the first inorganic particles 15 contain 80% by volume or more of particles having a particle size of 110 nm or less with respect to the total volume of the first inorganic particles 15. More preferably, all of the first inorganic particles 15 are 110 nm or less. In addition, the lower limit of the particle size of the 1st inorganic particle 15 is 3 nm or 30 nm, for example.

  The particle diameter of the second inorganic particles 17 is 160 nm or more. In this case, preferably, the second inorganic particles 17 include 90% by volume or more of particles having a particle diameter of 200 nm or more with respect to the total volume of the second inorganic particles 17. More preferably, all of the second inorganic particles 17 are 200 nm or more. The upper limit of the particle size of the second inorganic particles 17 is 5 μm or 600 nm.

  Further, when the inorganic particles contained in the dielectric 5 have a particle size distribution at a predetermined interval (for example, every 10 nm), the particle diameter and the large diameter side indicate the maximum frequency of the peaks on the small diameter side (first inorganic particles 15). The difference from the particle diameter indicating the maximum frequency of the peaks of the (second inorganic particles 17) is 100 nm or more, preferably 200 nm or more.

  The particle sizes of the first inorganic particles 15 and the second inorganic particles 17 are obtained, for example, by imaging the polished surface or fractured surface of the dielectric 5 with a scanning electron microscope (SEM) at an appropriate magnification (for example, 30000 times). It can be measured by observing the SEI (secondary electron image) and / or BEI (reflection electron image).

  The particle diameter is preferably calculated (measured) as the diameter of a circle having an area equivalent to the area of the particles observed in SEI and / or BEI (equivalent circle diameter). However, the maximum diameter may be a particle diameter.

  The plurality of inorganic particles constituting the dielectric 5 include, for example, 20% by volume or more and 90% by volume or less of the first inorganic particles 15 with respect to the total volume of the first inorganic particles 15 and the second inorganic particles 17. The second inorganic particles 17 are contained in an amount of 10% by volume or more and 80% by volume or less, more preferably, the first inorganic particles 15 are contained in an amount of 20% by volume or more and 40% by volume or less, and the second inorganic particles 17 are contained in an amount of 60% by volume or more. Contains 80% by volume or less.

  In addition, when combined with a preferable volume ratio of the plurality of inorganic particles and the resin 19, the dielectric 5 is most preferably the first inorganic particles with respect to the total volume of the plurality of inorganic particles (15, 17) and the resin 19. 15 is contained in an amount of 12 to 28% by volume, the second inorganic particles 17 are contained in an amount of 36 to 56% by volume, and the resin 19 is contained in an amount of 30 to 40% by volume.

  The volume% of each particle or the like is, for example, the cross section of a plurality of (for example, 10) the area ratio (area%) of each particle occupying the dielectric 5 using the image analysis device or the like in the above-described SEI and / or BEI. It is measured by calculating the average value of the measured values and considering it as the content (volume%).

  The first inorganic particles 15 and the second inorganic particles 17 are made of different materials, for example. In this case, in another aspect, the plurality of inorganic particles constituting the dielectric 5 are composed of the plurality of first material particles 21 and the second material particles 23 made of a material different from the plurality of first material particles 21. Become. The particle size of the second material particles 23 is larger than the particle size of the first material particles 21.

  In addition, the 2nd material particle 23 with a particle size smaller than the particle size of the 1st material particle 21 in an error range (for example, less than 1 volume% of the whole inorganic particle) may exist. Hereinafter, unless otherwise specified, the first inorganic particles 15 and the second inorganic particles 17 are not particularly distinguished from the first material particles 21 and the second material particles 23, and the first inorganic particles 15 are mainly used. And the term second inorganic particle 17 is used.

  The discrimination between the first material particle 21 and the second material particle 23 (discrimination of the material constituting the particle) is performed based on, for example, elemental analysis by EDS (Energy Dispersive x-ray Spectroscopy). After determining the material by EDS, the particle diameters of the first material particles 21 and the second material particles 23 can be measured by measuring the particle diameters based on SEI and / or BEI as described above. it can.

The first inorganic particles 15 and the second inorganic particles 17 are preferably made of, for example, a material having a relatively large dielectric constant. An example of such a material having a high dielectric constant is a material having a perovskite structure. Examples of the material having a perovskite structure include barium titanate (BaTiO ₃ , relative dielectric constant: 1200 to 3000), strontium titanate (SrTiO ₃ , relative dielectric constant: 300), calcium titanate (CaTiO ₃ , relative dielectric constant: 200), barium strontium titanate (Ba _1-x Sr _x TiO ₃ , relative dielectric constant: 800-1500), barium calcium titanate (Ba _1-x Ca _x TiO ₃ , relative dielectric constant: 600-1200). .

The second inorganic particles 17 are made of a material having a larger dielectric constant than that of the first inorganic particles 15, for example. For example, the first inorganic particles 15 are formed of silica (SiO ₂ , relative dielectric constant: 3 to 4), whereas the second inorganic particles 17 are alumina (Al ₂ O ₃ , relative dielectric constant). Ratio: 8 to 11), titanium dioxide (TiO ₂ , relative dielectric constant: 83 to 183) or a material having the perovskite structure described above. Further, for example, the first inorganic particles 15 are formed of silica, alumina, or titanium dioxide, whereas the second inorganic particles 17 are formed of a material having the above-described perovskite structure. Further, for example, the first inorganic particles 15 are formed of a paraelectric material (strontium titanate or the like), whereas the second inorganic particles 17 are formed of a ferroelectric material (barium titanate or the like). .

  The plurality of first inorganic particles 15 are combined with each other to form a three-dimensional matrix structure (three-dimensional network structure, skeleton structure). The plurality of second inorganic particles 17 are connected to each other via a three-dimensional matrix structure including the plurality of first inorganic particles 15. Specifically, it is as follows.

  The plurality of first inorganic particles 15 are bonded to each other via the plurality of second neck portions 27. The second neck portion 27 is formed by, for example, material diffusion. However, the plurality of first inorganic particles 15 are not densified like a fired ceramic, and a plurality of first gaps G <b> 1 are formed between the plurality of first inorganic particles 15. That is, the plurality of first inorganic particles 15 form a three-dimensional matrix structure in the dielectric 5.

  In addition, each second inorganic particle 17 is bonded to the plurality of first inorganic particles 15 via the plurality of first neck portions 25. Note that the first neck portion 25 is also formed by, for example, diffusion of a substance, like the second neck portion 27. The plurality of second inorganic particles 17 are connected to each other through a three-dimensional matrix structure including the plurality of first inorganic particles 15. The first inorganic particles 15 and the second inorganic particles 17 are not densified, and a second gap G2 is formed between them.

  Most of the plurality of second inorganic particles 17 are not in direct contact with each other because the plurality of first inorganic particles 15 are interposed therebetween. Further, even if the plurality of second inorganic particles 17 are in direct contact with each other, they are not bonded to each other (the neck portion is not formed). Further, the width w2 of the second neck portion 27 is larger than the width w1 of the first neck portion 25. Both the first neck portion 25 and the second neck portion 27 are made of the same material as the first inorganic particles 15. In this case, the same material as the first inorganic particles 15 means that the component of the second inorganic particles 17 may be included in a trace amount (0.1% by mass or less as measured by EPMA analysis).

  The first gap G1 and the second gap G2 are formed when the first inorganic particles 15 are not densified, and the size is approximately (in order) about the particle size of the first inorganic particles 15. It is. The plurality of first gaps G1 are closed in the cross-sectional view, but are communicated with each other three-dimensionally. The plurality of first gaps G1 communicate with the main surface of the dielectric 5 directly or indirectly. The plurality of second gaps G2 also directly or indirectly communicate with the main surface of the dielectric 5.

  A plurality of gaps G <b> 3 are formed in the inorganic material composed of the plurality of first inorganic particles 15 and the plurality of second inorganic particles 17. Each gap G <b> 3 is configured with a plurality of first inorganic particles 15 and a plurality of second inorganic particles 17 on the inner peripheral surface thereof. The plurality of gaps G3 also communicate with the main surface of the dielectric 5 directly or indirectly.

  The resin 19 is filled in the first gap G1, the second gap G2, and the gap G3. Resin 19 is, for example, epoxy resin (relative dielectric constant: 2.5 to 6), polyimide resin (relative dielectric constant: 3.55), cyanoresin resin (relative dielectric constant: 15 to 20), polyvinyl butyral resin (PVB, Dielectric constant: 3.9-4), fluororesin (dielectric constant: 4-8), acrylic resin (dielectric constant: 2.7-4.5), polyethylene terephthalate resin (PET, relative dielectric constant: 2.9 to 3) and polypropylene resin (PP, relative dielectric constant: 2.2 to 2.3). In addition, as the resin 19, for example, a resin having a smaller dielectric constant than that of the first inorganic particles 15 and the second inorganic particles 17 or the second inorganic particles 17 may be used.

  FIG. 3A to FIG. 5B are diagrams illustrating a method for manufacturing the capacitor 1. The manufacturing method of the capacitor 1 proceeds sequentially from FIG. 3 (a) to FIG. 5 (b). FIG. 3A is a schematic perspective view of the ball mill. FIG. 3B and FIG. 3D to FIG. 5B are cross-sectional views corresponding to FIG. FIG. 3C is a partially enlarged cross-sectional view of the dielectric 5 as in FIG.

  First, as shown to Fig.3 (a), the 1st inorganic particle 15 and the 2nd inorganic particle 17 are mixed by a predetermined | prescribed compounding ratio using a ball mill, and it disperse | distributes to a solvent, and prepares a slurry. In addition, the compounding ratio (volume ratio) of the 1st inorganic particle 15 and the 2nd inorganic particle 17 is 2: 8-4: 6, for example, as mentioned above.

  The solvent is, for example, methanol, isopropanol, n-butanol, ethylene glycol, ethylene glycol monopropyl ether, methyl ethyl ketone, methyl isobutyl ketone, xylene, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dimethylacetamide, or from these It is an organic solvent containing a mixture of two or more selected.

  Next, as shown in FIG. 3B, the produced slurry is applied onto a carrier film 31, formed into a sheet, and dried (the solvent is evaporated), whereby the dielectric 5 (resin 19 at this time) is formed. A dielectric layer 33 made of an inorganic material is formed.

  The application of the slurry can be performed using, for example, a doctor blade, a dispenser, a bar coater, a die coater, or screen printing. The slurry is dried by heating and air drying, for example. The drying temperature is set to, for example, 20 ° C. or higher and lower than the boiling point of the solvent (the boiling point of the lowest boiling point when two or more solvents are mixed).

  During the drying, the bonding between the first inorganic particles 15 proceeds, and the bonding between the first inorganic particles 15 and the second inorganic particles 17 proceeds. However, since it is not heated to a high temperature, the neck structure (the first neck portion 25 and the second neck portion 27) can be maintained, and a skeleton structure is formed by the first inorganic particles 15 (the first gap G1 and the first neck portion). 2 gap G2 is formed).

  Since the first inorganic particles 15 have more active atomic movements than the second inorganic particles 17, the second neck portion 27 between the first inorganic particles 15 is the first inorganic particles 15 and the second inorganic particles 15. It becomes thicker than the first neck portion 25 with the inorganic particles 17. Further, for the same reason and / or due to a difference in diffusion coefficient, the first neck portion 25 is mainly composed of the first inorganic particles 15. In addition, the second inorganic particles 17 are difficult to bond because the first inorganic particles 15 are interposed between them, and even if they are in contact with each other, the movement of atoms is not active, so the two inorganic particles 17 are bonded. Hateful. Such a binding mode is likely to occur suitably when the particle diameter of the first inorganic particles 15 is 110 nm or less and the particle diameter of the second inorganic particles 17 is 200 nm or more.

  Further, as the bonding of the first inorganic particles 15 progresses, the entire first inorganic particles 15 contract as a whole, and the gap G3 is formed. The gap G3 is, for example, 60% by volume or more of the second inorganic particles 17 with respect to the total volume of the first inorganic particles 15 and the second inorganic particles 17; If it is relatively large, it is likely to be formed.

  The carrier film 31 may be formed of an appropriate material such as a resin, but is preferably formed of polyethylene terephthalate (PET) from the viewpoint of heat resistance, mechanical strength, and cost.

  Next, as shown in FIG. 3C, the dielectric layer 33 is impregnated with a molten or liquid resin. For example, the resin that does not impregnate the dielectric layer 33 while the resin is applied to the main surface of the dielectric layer 33 is recovered by a spin coater. A necessary and sufficient amount of resin may be supplied to the dielectric layer 33 by screen printing or the like. Impregnation is performed by capillary force. When the impregnated molten or liquid resin is cured, the resin 19 filled in the first gap G1, the second gap G2, and the gap G3 is formed.

  Thereafter, although not particularly illustrated, the dielectric layer 33 is subjected to heat treatment. Thereby, the coupling | bonding of particle | grains becomes strong. This heating temperature is preferably less than the crystal start temperature of the inorganic material in order to suppress grain growth of the inorganic material, and is preferably equal to or higher than the boiling point of the solvent in order to evaporate the remaining solvent. For example, when the 1st inorganic particle 15 consists of silica (crystallization start temperature 1300 degreeC), heating temperature is 100-600 degreeC. In addition, this heat treatment may be performed before impregnation of the dielectric layer 33 with resin.

  Next, as shown in FIG. 3D, the internal electrode 7 is formed on the dielectric 5. For example, the patterned internal electrode 7 is formed by vapor-depositing a metal to be the internal electrode 7 on the dielectric 5 through a metal mask. The internal electrode 7 may be formed by plating, photolithography, metal foil transfer, or the like.

  Then, by repeating the steps described with reference to FIGS. 3B to 3D, as shown in FIG. 4A and FIG. 4B, the dielectric 5 (dielectric layer 33). And the internal electrode 7 is laminated | stacked. In addition, the usage-amount of the carrier film 31 can be reduced by laminating | stacking by repeating coating in this way. Alternatively, a method of laminating the dielectric layer 33 formed with the internal electrodes 7 shown in FIG. 3D while sequentially peeling the carrier film 31 may be used.

  In addition, the laminated body 8 may be strengthened between the dielectric layer 33 and the internal electrode 7 and between the dielectric layers 33 through a temporary press composed of a uniaxial press and a main press composed of an isostatic press.

  Thereafter, as shown in FIG. 4C, the carrier film 31 is peeled off, and the dielectric layer 33 is cut into individual pieces using a dicing blade or a laser.

  Next, the external electrode 9 is formed as shown in FIG. For example, the external electrode 9 is formed by spraying metal on the side surface of the multilayer body 8 including the dielectric 5 and the internal electrode 7. Alternatively, the outer layer of the external electrode 9 may be plated with Sn or the like by aligning the plurality of laminated bodies 8 with a dip jig and allowing the side surfaces of the laminated bodies 8 to penetrate into the plating solution.

  Next, as shown in FIG. 5B, the lead 4 is bonded to the external electrode 9. For example, the lead 4 is joined to the external electrode 9 by welding. When laser welding is used, it is preferable that the exterior of the lead 4 and the external electrode 9 is covered with Sn that easily absorbs laser.

  And the exterior part 11 is formed as shown in FIG.2 (b). For example, first, an undercoat resin is impregnated in the whole chip in a vacuum atmosphere, and then thermosetting or ultraviolet curing is performed according to the resin type. Thereafter, a resin mainly composed of epoxy is applied by powder coating or the like and cured. Thus, the exterior portion 11 is formed, and as a result, the capacitor 1 is manufactured.

  As described above, the capacitor 1 according to the embodiment includes the pair of internal electrodes 7 and the dielectric 5 positioned between the pair of internal electrodes 7. The dielectric 5 includes a plurality of first inorganic particles 15 having a particle size of 130 nm or less and a plurality of second inorganic particles 17 having a particle size of 160 nm or more. The second inorganic particles 17 are connected to each other through a three-dimensional matrix structure formed by bonding a plurality of first inorganic particles 15 to each other.

  Therefore, the electric field concentration around the second inorganic particles 17 can be suppressed by the three-dimensional matrix structure, and the withstand voltage can be increased. Further, the bondability between the dielectric 5 and the internal electrode 7 is improved by the anchor effect of the three-dimensional matrix structure. In addition, since the dielectric 5 is not fired, and hence the internal electrode 7 is not oxidized by firing, it is easy to use a metal that is easily oxidized, such as Cu, as the internal electrode 7. In addition, for example, if the dielectric 5 is composed of only the second inorganic particles 17, it is difficult to dispose many other second inorganic particles 17 around one second inorganic particle 17. The three-dimensional matrix structure is not dense, and the effect of suppressing electric field concentration is not exhibited, or the contact area is reduced, but such inconvenience does not occur.

  In the capacitor 1, at least one of the first inorganic particles 15 and the second inorganic particles 17 has a perovskite structure. Accordingly, the dielectric constant of the dielectric 5 can be increased, and in combination with the fact that a high voltage can be applied by improving the withstand voltage, a capacitor having a large capacity can be realized.

  In the capacitor 1, the first inorganic particles 15 and the second inorganic particles 17 are bonded via the first neck portion 25. Therefore, compared with the case where the second inorganic particles 17 are held in a three-dimensional matrix structure by simply contacting the first inorganic particles 15 and the second inorganic particles 17, the strength of the dielectric 5 is higher. improves.

  In the capacitor 1, the first neck portion 25 is made of the same material as the first inorganic particles 15. Therefore, for example, unevenness due to the material of the second inorganic particles 17 is suppressed on the outer peripheral surface of the second inorganic particles 17, and as a result, even if the dielectric constant of the second inorganic particles 17 is increased, Electric field concentration is suppressed from occurring locally on the outer peripheral surface. Moreover, the dielectric constant can be improved while improving the strength by using the first inorganic particles 15 as a material suitable for bonding and the second inorganic particles 17 as a material having a high dielectric constant.

  In the capacitor 1, the first inorganic particles 15 are bonded to each other via the second neck portion 27. Accordingly, the first inorganic particles 15 are bonded together by bonding based on the diffusion of the substance, and are firmly bonded. Moreover, since both the coupling | bonding of the 1st inorganic particles 15 and the coupling | bonding of the 1st inorganic particle 15 and the 2nd inorganic particle 17 are via a neck part, a manufacturing method is simplified. The

  In the capacitor 1, the resin 19 exists between the first inorganic particles 15 having a three-dimensional matrix structure. Therefore, compared to the case where the first gap G1 between the first inorganic particles 15 is in a vacuum, etc., the dielectric constant inside the dielectric 5 can be improved to increase the capacity, and the particles and their It is possible to reduce the difference in dielectric constant from the outside and suppress the occurrence of electric field concentration and improve the dielectric strength. Furthermore, the strength of the three-dimensional matrix structure is reinforced by the resin 19.

  In the capacitor 1, the second inorganic particles 17 are not directly bonded to each other. Accordingly, the presence of large particles in which the second inorganic particles 17 are bonded to each other is suppressed, and as a result, the occurrence of anisotropy with respect to the electrical characteristics and mechanical characteristics is suppressed.

  In the capacitor 1, the width w 2 of the second neck portion 27 is larger than the width w 1 of the first neck portion 25. From another viewpoint, the three-dimensional matrix structure has a difference in thickness between the thick portion (first inorganic particles 15) and the thin portion (second neck portion 27). As a result, the electric field can be appropriately bypassed around the second inorganic particles 17. In addition, the bonding between the first inorganic particles 15 constituting the three-dimensional matrix structure is made stronger, and the mechanical strength of the dielectric 5 is also improved.

  In the capacitor 1, the first inorganic particles 15 have a first dielectric constant, and the second inorganic particles 17 have a second dielectric constant higher than the first dielectric constant. Therefore, it is possible to obtain the dielectric 5 having an arbitrary dielectric constant by appropriately changing the blending ratio of the first inorganic particles 15 and the second inorganic particles 17. In general, since a material having a high dielectric constant has a large dielectric loss, the dielectric constant and the dielectric loss are suitably balanced as compared with the case where the dielectric 5 is formed only from the material having the second dielectric constant. It is possible to meet the required specifications.

(Example)
For the dielectric 5 of the embodiment, specific materials are selected, dimensions are set, etc., the dielectric (sample) according to the example is manufactured, the polished surface is observed by SEM, and the dielectric strength is examined. It was. Specifically, it is as follows.

(Manufacturing Method of Dielectric of Example)
First, the following first inorganic particles and second inorganic particles were prepared.
First inorganic particles:
Material: Silica, particle size: 130 nm or less (average particle size 60 nm)
Second inorganic particles:
Material: Barium titanate, particle size: 160 nm or more (average particle size 340 nm)

  The first inorganic particles and the second inorganic particles were blended in a volume ratio of 3: 7, and dispersed in MEK (methyl ethyl ketone) to prepare a slurry.

  Thereafter, the slurry was applied on a carrier film using a coater, formed into a sheet shape, and dried to obtain a dielectric layer 33 having a thickness of 10 μm. Next, the dielectric material 5 was produced by impregnating the sheet with an epoxy resin and performing heat treatment at a temperature of 80 to 250 ° C.

(Manufacturing method of dielectric of comparative example)
As a comparative example, a 10 μm thick sheet prepared from a slurry prepared by mixing the same barium titanate particles and epoxy resin as the second inorganic particles was heated under the same conditions (80 to 250 ° C.) to produce a dielectric. did.

  Then, an Al film was formed on almost the entire main surfaces of the dielectrics of the above-described examples and comparative examples to prepare a sample.

(Method of measuring particle size of dielectric material of example)
The dielectric 5 produced as described above was polished to expose the first inorganic particles and the second inorganic particles.

  Next, SEI and BEM were obtained by SEM at a magnification of 30000 times. Of these, a region having a length and width of about 20 μm × about 15 μm was selected, and the particles were analyzed.

  In the analysis of the particles, first, each observed particle was subjected to elemental analysis by EDS to discriminate between silica and barium titanate.

  Next, the particle size was measured using image analysis type particle size distribution measurement software “Macview” manufactured by Mountec. Specifically, first, the particles determined by EDS were specified one by one, and the particle region was determined by the software function. Next, the equivalent circle diameter was calculated from the area of the region determined by the software, and the value was defined as the particle diameter, and the maximum value, minimum value, and average value of the particle diameter were obtained. Silica particles were analyzed for particle size from SEI. The particle diameter of the barium titanate particles was analyzed from BEI.

(Analysis result of Example)
FIG. 6 is an example of SEI related to the dielectric 5 of the embodiment, and FIG. 7 is an enlarged image of a region VII in FIG. However, these photographs are before resin impregnation. As shown in these photographs, the second inorganic particles 23 are connected by a three-dimensional matrix structure formed by the plurality of first inorganic particles 21.

  FIG. 8 is a diagram showing the particle size distribution according to the example obtained from the result of the analysis. The horizontal axis indicates the particle size by a logarithmic axis, and the vertical axis indicates volume%. Volume% is the volume ratio of each particle to the volume of all particles in the region to be analyzed. A solid line L1 indicates the particle diameter and volume% of the first inorganic particles, a solid line L2 indicates the particle diameter and volume% of the second inorganic particles, and a solid line L3 indicates the cumulative volume% of all particles.

The minimum value, the maximum value, and the average value of the particle diameters of the first inorganic particles and the second inorganic particles in this example were as follows.
Minimum value (nm) Maximum value (nm) Average value (nm)
First material particles 31 123 56
Second material particles 161 539 332

The breakdown electric field strength of the produced sample was measured using an AC power source. The results were as follows.
Comparative example: 43.2 (V / μm)
Example: 57.3 (V / μm)
Thus, the example showed a higher breakdown field strength than the comparative example.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The capacitor is not limited to the multilayer type, and may be, for example, a single plate type having only one dielectric, or a wound type in which a dielectric and an electrode are wound. . Further, the capacitor is not limited to the one with leads, and may be, for example, a chip type that is surface-mounted. The capacitor may be configured as a part of the circuit board. In addition, the capacitor may be one in which two stacked electrodes are opposed to each other with a dielectric interposed therebetween, or a plurality of pairs of electrodes may be connected in series.

  In the case where the capacitor is a multilayer type, a block body in which a plurality of dielectrics are stacked may be stacked via an adhesive layer. This adhesive layer may be located between the dielectrics or between the electrodes. The outermost layer may be a resin layer instead of the dielectric (dielectric outside the electrode).

  The first inorganic particles and the second inorganic particles may be composed of the same material. For example, both the first inorganic particles and the second inorganic particles may be made of silica.

  DESCRIPTION OF SYMBOLS 1 ... Capacitor, 5 ... Dielectric, 7 ... Internal electrode (electrode), 15 ... 1st inorganic particle, 17 ... 2nd inorganic particle.

Claims (8)

A pair of electrodes;
A dielectric located between the pair of electrodes and comprising a resin ;
Have
The dielectric is
Particle size and more of the following non-aircraft paraelectric particles 130 nm,
Particle size comprises a plurality of non-aircraft ferroelectric particles above 160 nm,
The difference between the particle size indicating the maximum frequency of the peaks of the inorganic paraelectric particles and the particle size indicating the maximum frequency of the peaks of the inorganic ferroelectric particles in the particle size distribution is 100 nm or more,
Before cinchona machine ferroelectric particles each other, capacitors that are connected via a three-dimensional matrix structure formed by combining the plurality of non-aircraft paraelectric particles together. Capacitor of claim 1 wherein at least one of the previous cinchona machine paraelectric particles and before quinic machine ferroelectric particles having a perovskite structure. Before cinchona machine paraelectric particles and before quinic machine ferroelectric particles capacitor according to claim 1 or 2 is attached via a first neck portion. Capacitor according to claim 3, wherein the first neck portion is made of pre-quinic machine paraelectric particles of the same material. Capacitor according to claim 3 before quinic machine paraelectric grains are bonded to each other through a second neck portion. Capacitor according to claim 1, there is a resin to between quinic machine paraelectric particles before forming the three-dimensional matrix structure. The number of other pre-quinic machine ferroelectric particles in contact with the front respectively quinic machine ferroelectric particles, prefrontal each quinic machine ferroelectric particles in contact with quinic machine paraelectric particles The capacitor according to claim 3. Before cinchona machine paraelectric particles have a first dielectric constant, pre-quinic machine ferroelectric particles of claims 1 to 7 having a second dielectric constant higher than the first dielectric constant The capacitor according to any one of the above items.