JP2018182274A - Multilayer capacitor - Google Patents

Abstract

An object of the present invention is to provide a multilayer capacitor that secures a capacity, reduces an equivalent series resistance, and improves reliability. A conductive resin layer of an external electrode is disposed on a surface of a main body where an internal electrode is exposed. The conductive resin layer includes metal particles 131a, a conductive connection part 131b surrounding the metal particles, and an intermetallic compound 150 is formed at one end of the internal electrode. The conductive connection part may reduce the ESR (Equivalent Series Resistance) of the multilayer ceramic capacitor by contacting the intermetallic compound and the first electrode layer 132, thereby improving the bending strength and reliability. [Selection diagram] FIG.

Description

  The present invention relates to a multilayer capacitor.

  A multilayer capacitor is an important chip component used in the communication, computer, home appliance, automobile and other industries because it has the advantages of small size, high capacity, and easy mounting. , Passive elements that are the core of various electric, electronic, and information communication devices such as computers and digital TVs.

  In recent years, with the miniaturization and high performance of electronic devices, the multilayer capacitors also tend to be smaller and higher in capacity, and such a tendency makes importance for securing high reliability of the multilayer capacitors higher. ing.

  As a plan for securing high reliability of such a multilayer capacitor, in order to absorb tensile stress (stress) generated in mechanical or thermal environment and to prevent generation of crack due to stress, A technique for applying a conductive resin layer to an external electrode is disclosed.

  Such a conductive resin layer electrically and mechanically joins between the sintered electrode layer of the external electrode of the multilayer capacitor and the plating layer, and mechanically at the process temperature generated during mounting on the circuit substrate. It also plays a role in protecting the multilayer capacitor from thermal stress and substrate warpage impact.

  Conventionally, after the sintered electrode layer is applied to secure the electric and mechanical bonding force with the internal electrode by the low electric and mechanical bonding force of the conductive resin layer, the conductive resin layer is conducted on the sintered electrode layer. Forming a conductive resin layer.

  However, with such a structure, a crack is generated by the sintered electrode layer, and there is a limit in protecting the multilayer capacitor from mechanical and thermal stress due to temperature and warpage impact of the substrate.

  Also, in the conventional structure, when the conductive resin layer directly contacts the internal electrode without the sintered electrode layer, the electrical and mechanical bonding strength is reduced, the capacity is reduced, and the ESR (equivalent series resistance: There may be a problem that the Equivalent Series Resistance) increases.

JP, 2005-051226, A Patent No. 5104313 gazette

  The object of the present invention is to apply a conductive resin layer as a primary external electrode layer, to improve the electric and mechanical bonding strength between the internal electrode and the conductive resin layer, to secure a capacity, equivalent series It is an object of the present invention to provide a multilayer capacitor which can reduce the equivalent series resistance (ESR) and improve the reliability.

  One aspect of the present invention includes a plurality of dielectric layers and a plurality of first and second inner electrodes alternately arranged via the dielectric layer, and the first and second surfaces facing each other, the first And the second surface, the third and fourth surfaces facing each other, the first and second surfaces connected with each other, and the third and fourth surfaces connecting the fifth and sixth surfaces facing each other And a plurality of first and second grooves disposed between the upper and lower dielectric layers on the third and fourth surfaces such that one end of each of the first and second inner electrodes is exposed. And an intermetallic compound disposed in the first and second grooves and connected to one end of each of the first and second internal electrodes, and the third and fourth surfaces of the main body. First and second external electrodes disposed respectively, the first and second external electrodes being disposed on the body A conductive resin layer including a plurality of metal particles, a plurality of metal particles, a conductive connection portion surrounding the plurality of metal particles and contacting with the intermetallic compound, and a base resin, and the conductive resin layer And a first electrode layer disposed on and in contact with the conductive connection portion.

  According to an embodiment of the present invention, by securing the capacitance of the multilayer capacitor at a certain level, it is possible to reduce the ESR and to improve the bending strength and the reliability.

1 is a perspective view schematically illustrating a multilayer capacitor according to an embodiment of the present invention. It is sectional drawing of the II 'line | wire of FIG. It is sectional drawing which expanded and showed the A area | region of FIG. It is sectional drawing of A area | region of FIG. 2 when metal particle | grains consist of flake shape. It is sectional drawing of A area | region of FIG. 2 when metal particle | grains consist of spherical and flake shaped mixed type. It is a phase diagram showing that copper particles and tin-bismuth particles were dispersed in epoxy. It is the phase diagram which showed that the oxide film of the copper particle was removed by an oxide film removal agent or heat. FIG. 5 is a phase diagram showing that an oxide film removing agent or heat removes an oxide film of tin / bismuth particles. FIG. 6 is a phase diagram showing that tin / bismuth particles melt and have fluidity. FIG. 5 is a phase diagram showing that copper particles and tin / bismuth particles react to form an intermetallic compound. FIG. 7 is a cross-sectional view schematically illustrating a multilayer capacitor in accordance with another embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention can be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Also, embodiments of the present invention are provided to more fully describe the present invention to one of ordinary skill in the art. Accordingly, the shapes and sizes of elements in the drawings may be scaled (or highlighted or simplified) for clearer explanation.

  Note that components having the same function within the scope of the same concept shown in the drawings of each embodiment will be described using the same reference symbols.

  Furthermore, in the entire specification, “including” a certain component may not include the other component, and may further include other component unless specifically described otherwise. It means that.

  Also, throughout the specification, being formed "on" means not only being formed in direct contact, but it may further include other components in between.

  In order to clearly explain the present invention, parts not related to the explanation are omitted in the drawings, and the thickness is shown enlarged to clearly express various layers and regions, and functions within the same idea range. The same components will be described using the same reference numerals.

Multilayer Capacitor FIG. 1 is a perspective view showing a multilayer capacitor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II ′ of FIG.

  Referring to FIGS. 1 and 2, the multilayer capacitor 100 according to an embodiment of the present invention includes a body 110 and first and second outer electrodes 130 and 140.

  The main body 110 may include an active region as a portion contributing to the formation of capacitance of the capacitor, and upper and lower covers 112 and 113 formed on upper and lower portions of the active region as upper and lower margin portions, respectively.

  In one embodiment of the present invention, the shape of the main body 110 is not particularly limited, but may be substantially hexahedral.

  That is, the main body 110 may have a shape close to a hexahedron, though not a perfect hexahedron, due to the difference in thickness due to the arrangement of the internal electrodes, and the polishing of the corners.

  When defining the direction of the hexahedron to clearly describe the embodiment of the present invention, X, Y and Z shown on the drawings indicate the length direction, the width direction and the thickness direction, respectively.

  Here, the thickness direction can be used as the same concept as the stacking direction in which the dielectric layers are stacked.

  Further, in the main body 110, both surfaces facing each other in the Z direction are defined as first and second surfaces 1, 2 and connected with the first and second surfaces 1, 2 and the both surfaces facing each other in the X direction are third And fourth surfaces 3 and 4, connected to the first and second surfaces 1 and 2, and connected to the third and fourth surfaces 3 and 4, and both surfaces facing each other in the Y direction are the fifth and sixth Define as faces 5 and 6. In this case, the first surface 1 may be a mounting surface.

  The active region may have a structure in which a plurality of dielectric layers 111 and a plurality of first and second inner electrodes 121 and 122 are alternately stacked via the dielectric layers 111.

  Also, in the active region, dielectric layers 111 disposed one above the other so that one end portions of the first and second internal electrodes 121 and 122 are exposed to the third and fourth surfaces 3 and 4 of the main body 100, respectively. And a plurality of first and second groove portions are formed therebetween.

  Furthermore, intermetallic compounds 150 in contact with one end portions of the first and second inner electrodes 121 and 122 are disposed in the first and second groove portions.

The dielectric layer 111 may include ceramic powder having a high dielectric constant, such as barium titanate (BaTiO ₃ ) or strontium titanate (SrTiO ₃ ) powder, but the present invention is limited thereto is not.

  At this time, the thickness of the dielectric layer 111 can be arbitrarily changed according to the capacitance design of the multilayer capacitor 100, and the thickness of one layer after firing is set to 0 in consideration of the size and capacitance of the main body 110. Although it can be set to 1 to 10 μm, the present invention is not limited to this.

  The first and second inner electrodes 121 and 122 may be disposed to face each other through the dielectric layer 111.

  The first and second inner electrodes 121 and 122 are a pair of electrodes having different polarities, and print a conductive paste containing a conductive metal with a predetermined thickness on the dielectric layer 111, and the dielectric layer It may be formed to be alternately exposed from the third and fourth surfaces 3 and 4 of the main body 110 along the laminating direction of the dielectric layer 111 through the interlayer dielectric 111 disposed in the middle. It can be electrically isolated from one another.

  The first and second inner electrodes 121 and 122 may be exposed to the first and second outer electrodes 130 and 140 by the intermetallic compound 150 in portions alternately exposed from the third and fourth surfaces 3 and 4 of the main body 110. Each may be electrically connected.

  Therefore, when a voltage is applied to the first and second outer electrodes 130 and 140, charges are accumulated between the first and second inner electrodes 121 and 122 facing each other by the intermetallic compound 150. The capacitance of the capacitor 100 is proportional to the area of the overlapping regions of the first and second inner electrodes 121 and 122.

  The thickness of the first and second inner electrodes 121 and 122 may be determined according to the application, for example, 0.2 to 1.0 μm in consideration of the size and capacity of the ceramic body 110. However, the present invention is not limited to this.

  Also, the conductive metal contained in the first and second inner electrodes 121 and 122 may be any of nickel (Ni), copper (Cu), palladium (Pd), or an alloy thereof, but the present invention Is not limited to this. In the present embodiment, when the first and second inner electrodes 121 and 122 are nickel, the intermetallic compound 150 may be nickel-tin (Ni-Sn).

  The upper and lower covers 112 and 113 may have the same material and configuration as the dielectric layer 111 of the active region except that they do not include the internal electrodes.

  That is, the upper and lower covers 112 and 113 can be considered to be formed by laminating a single dielectric layer or two or more dielectric layers on the upper and lower surfaces of the active region in the Z direction, respectively. Basically, damage to the first and second inner electrodes 121, 122 due to physical or chemical stress can be prevented.

  The first and second outer electrodes 130 and 140 may include the conductive resin layers 131 and 141 and the first electrode layers 132 and 142 disposed on the conductive resin layers 131 and 141, respectively.

  The conductive resin layers 131 and 141 are exposed by the intermetallic compound 150 formed in the first and second groove portions on the third and fourth surfaces 3 and 4 of the main body 110, and the first and second inner electrodes 121, By being connected to and connected to each of the electrodes 122, electrical conduction between the first outer electrode 130 and the first inner electrode 121 and electric conduction between the second outer electrode 140 and the second inner electrode 122 are secured. .

  At this time, the conductive resin layers 131 and 141 are connected to the connection portions respectively formed on the third and fourth surfaces 3 and 4 of the main body 110 and the first and second surfaces 1 and 2 of the main body 110 from the connection portions. It is possible to include a band portion which is formed to extend to a part and a part of the fifth and sixth surfaces 5 and 6, respectively.

  As described above, when the conductive resin layers 131 and 141 are formed on the third and fourth surfaces 3 and 4 of the main body 110, the permeation prevention characteristics of the plating solution and moisture can be improved.

  The first electrode layers 132 and 142 are disposed on the conductive resin layers 131 and 141, and are in contact with the conductive connection portions of the conductive resin layers 131 and 141, which will be described later. Therefore, the first electrode layers 132 and 142 can further improve the penetration preventing property of the plating solution and the water.

  In addition, the first electrode layers 132 and 142 may include a metal component, and the metal component may be any of copper (Cu), tin (Sn), nickel (Ni), palladium (Pd), and gold (Au). Or these alloys may be sufficient, but this invention is not limited to this.

  Such first electrode layers 132 and 142 may be formed by plating copper, or may be formed by a thin film deposition process such as CVD / PVD.

  FIG. 3 is a cross-sectional view showing a region A of FIG. 2 in an enlarged manner.

  Although the A region is an enlarged view of a part of the first outer electrode 130, the first outer electrode 130 is electrically connected to the first inner electrode 121, and the second outer electrode 140 is a second. Since the configurations of the first external electrode 130 and the second external electrode 140 are similar except that they are connected to the internal electrode 122, the following description will be made based on the first external electrode 130, and the second external electrode 140. A description of is included.

  As shown in FIG. 3, the conductive resin layer 131 of the first outer electrode 130 includes a plurality of metal particles 131a, a conductive connection portion 131b in contact with the intermetallic compound 150, and a base resin 131c. .

  The conductive resin layer 131 as described above electrically and mechanically joins the intermetallic compound 150 and the first electrode layer 132, and at the time of mounting the multilayer capacitor 100 on a substrate, mechanical or thermal environment. By absorbing the tensile stress (stress) generated in the above, it is possible to prevent the generation of a crack and also play a role of protecting the multilayer capacitor 100 from the impact of warpage of the substrate.

  At this time, the conductive resin layer 131 can be formed by applying a paste in which a plurality of metal particles 131a are dispersed in the base resin 131c on the third surface 3 of the main body 100, and performing a drying and curing process.

  Therefore, unlike the conventional method of forming the external electrode by firing, the metal particles are not completely melted, and thus exist in a form dispersed in a random distribution in the base resin 131 c and included in the conductive resin layer 131 be able to.

  On the other hand, when all the metal particles 131 a react with the conductive connection portion 131 b and the low melting point metal forming the intermetallic compound 150, the metal particles 131 a may not exist in the conductive resin layer 131.

  However, in the present embodiment to be described later, for convenience of description, the metal particles 131 a are included in the conductive resin layer 131.

  At this time, the metal particles 131a are copper (Cu) or at least one of nickel (Ni), silver (Ag), copper coated with silver (Cu), copper coated with tin (Sn) It can contain one or more.

  In addition, the size of the metal particles 131a can be 0.2 to 20 μm.

  In addition, the metal particles contained in the conductive resin layer 131 may not only be spherical, but may be made of only flake-like metal particles 131a ′ as needed, as shown in FIG. Alternatively, as shown in FIG. 5, it may be a mixed type of spherical metal particles 131a and flake-like metal particles 131a ′.

  The conductive connection portion 131 b surrounds and connects the plurality of metal particles 131 a in a molten state in a molten state, thereby minimizing internal stress of the main body 110 and improving high temperature load and moisture resistance load characteristics. it can.

  Such a conductive connection portion 131 b can increase the electrical conductivity of the conductive resin layer 131 and reduce the resistance of the conductive resin layer 131.

  At this time, when the conductive resin layer 131 includes the metal particles 131 a, the conductive connection portion 131 b can improve the connectivity between the metal particles 131 a and further reduce the resistance of the conductive resin layer 131.

  In addition, the low melting point metal contained in the conductive connection portion 131 b can have a melting point lower than the curing temperature of the base resin 131 c.

  At this time, the low melting point metal contained in the conductive connection portion 131 b can preferably have a melting point of 300 ° C. or less.

  Specifically, the metal contained in the conductive connection portion 131b is selected from tin (Sn), lead (Pb), indium (In), copper (Cu), silver (Ag), and bismuth (Bi). Can consist of two or more alloys.

  At this time, when the conductive resin layer 131 includes the metal particles 131a, the conductive connection portion 131b can be connected to each other by surrounding the plurality of metal particles 131a in a molten state.

  That is, since the low melting point metal contained in the conductive connection portion 131b has a melting point lower than the curing temperature of the base resin 131c, it melts in the process of drying and curing, and as shown in FIG. The metallic connection portion 131b can cover the metal particles 131a in a molten state.

The conductive resin layer 131 is formed by dipping after forming a low melting point solder resin paste, but when applying a metal coated with silver or silver as the metal particles 131a at the time of manufacturing the low melting point solder resin paste, The sex connection part 131 b may include Ag ₃ Sn.

  Here, the first and second inner electrodes 121 and 122 may include nickel (Ni), and in this case, the intermetallic compound 150 may include nickel-tin (Ni-Sn).

  When a paste in which metal particles are dispersed is used as an electrode material, the flow of electrons is smooth when it is metal-metal contact, but when the base resin surrounds the metal particles, the flow of electrons is It may decrease sharply.

  In order to solve such problems, the amount of base resin can be extremely reduced and the amount of metal can be increased to improve the conductivity by improving the contact ratio between metal particles. There is a possibility that the problem of reduction in the adhesion strength of the external electrode may occur.

  In the present embodiment, even if the amount of the thermosetting resin is not extremely reduced, the contact ratio between the metal particles can be increased by the conductive connection portion, and the conductive resin can be obtained without decreasing the fixing strength of the external electrode. Electrical conductivity in the layer can be improved. This can also reduce the ESR of the multilayer capacitor.

  The intermetallic compound 150 is disposed in the first and second groove portions, and contacts the conductive connection portion 131b to connect the first or second inner electrode 121, 122 and the conductive connection portion 131b. At this time, the exposed surface of the intermetallic compound 150 may form a substantially flat surface with the third or fourth surface 3 or 4 of the main body, and the intermetallic compound in the conductive resin layer 131 according to the embodiment. 150 may be further formed.

  Thereby, the electrical and mechanical bonding between the conductive resin layer 131 and the first or second inner electrode 121, 122 is improved, and the contact between the conductive resin layer 131 and the first or second inner electrode 121, 122 is achieved. Reduce resistance.

  The base resin 131c can include a thermosetting resin having electrical insulation.

  At this time, the thermosetting resin may be, for example, an epoxy resin, but the present invention is not limited thereto.

  The base resin 131 c mechanically bonds between the main body 110 and the first electrode layer 132.

  A second electrode layer may be further disposed on the first electrode layers 132 and 142.

  In this case, the second electrode layer may be a plating layer, but the second electrode layer may be, for example, a first nickel (Ni) plating layer 133, 143 and a first tin (Sn) plating layer 134, 144. The electrode layers 132 and 142 may be stacked in this order. Meanwhile, the second electrode layer may be formed using nickel or tin in a thin film deposition method such as CVD / PVD.

Formation Mechanism of Conductive Resin Layer FIG. 6 is a phase diagram showing that copper particles and tin-bismuth particles are dispersed in epoxy, and FIG. 7 is an oxide film removing agent or heat removes the oxide film of copper particles. FIG. 8 is a phase diagram showing that the oxide film removing agent or heat removes the oxide film of the tin / bismuth particles, and FIG. 9 is a phase diagram showing that the tin / bismuth particles melt and flow FIG. 10 is a phase diagram showing that a copper particle and a tin / bismuth particle react to form a copper-tin layer.

  Hereinafter, with reference to FIGS. 6 to 10, the mechanism for forming the conductive resin layer 131 will be described.

  The conductive resin layer in the present embodiment includes a plurality of metal particles, a low melting point metal, and a base resin, wherein the metal particles are coated with nickel, silver, silver coated copper, tin, tin At least one of the copper can be used. In the present embodiment, copper particles will be described as an example.

  In addition, Sn-based solder can be used as the low melting point metal. Although Sn / Bi (tin / bismuth particles) is used in this embodiment, Sn-Pb, Sn-Cu, Sn-Ag, Sn-Ag-Cu, etc. may be applied to others. Further, the base resin is described as using an epoxy resin.

  6 to 8, surfaces of copper particles 310 as metal particles having a high melting point contained in an epoxy resin as base resin 131 c and surfaces of tin / bismuth (Sn / Bi) particles 410 which are low melting point metals. The oxide films 311 and 411 are respectively present in Further, the oxide film 121 a is also present on the surface of the first inner electrode 121.

  The oxide films 311 and 411 cause the copper particles 310 and the tin / bismuth particles 410 to react with each other to prevent the formation of the copper-tin layer, but the oxide film remover or heat contained in the epoxy during curing It can be removed by (.DELTA.T) or, if necessary, by acid solution treatment. At this time, the oxide film 121a of the first inner electrode 121 may be removed together.

  Although an acid, a base, hydrogen halide etc. can be used as said oxide film removal agent, this invention is not limited to this.

  Referring to FIGS. 9 and 10, the oxide film-removed tin / bismuth particles start to melt at about 140 ° C., and the oxide film is removed copper while the melted tin / bismuth particles 410 have fluidity. It moves toward the particle 310 and reacts with the copper particle 310 at a certain temperature to form the conductive connection portion 131 b, and moves to the first groove side of the main body 110 where the first internal electrode 121 is exposed, as shown in FIG. As shown in 10, an intermetallic compound 150, which is a copper-tin layer, is formed in the first groove.

  The thus formed intermetallic compound 150 is connected to the conductive connection portion 131 b made of copper-tin of the conductive resin layer to reduce the contact resistance between the first inner electrode 121 and the conductive resin layer. it can.

  The copper particles 131a shown in FIG. 10 indicate copper particles present in the conductive connection portion 131b after the reaction as described above.

  At this time, surface oxidation of the tin / bismuth particles 410 is likely to occur, which may hinder the formation of the intermetallic compound 150. Therefore, in order to prevent such surface oxidation, tin / bismuth particles can be surface-treated as needed so that the carbon content is 60.5 to 1.0%.

  Meanwhile, the size of the metal particles for forming the intermetallic compound may be 0.2 to 20 μm. At this time, the metal particles may be at least one of nickel, silver, copper coated with silver, copper coated with tin, and copper.

  In order to form an intermetallic compound, tin / bismuth particles that melt at a constant temperature and exist in a solution state must flow into the grooves of the main body and around the metal particles, but when the size of the metal particles exceeds 20 μm The spacing between the body and the metal particles may be too wide, and the tin / bismuth solution may not easily move between the grooves of the body and the metal particles, which may interfere with the formation of intermetallic compounds.

  On the contrary, when the size of the metal particles is 20 μm or less, the distance between the metal particles is reduced, and the capillary force generated in the region thus reduced allows the tin / bismuth solution to more easily move to the groove of the main body. Thus, the formation of intermetallic compounds is facilitated.

  However, if the size of the metal particles is less than 0.2 μm, oxidation may occur on the surface of the metal particles, which in turn may interfere with the formation of intermetallic compounds.

  Also, in this mechanism, the melting temperature of the tin-bismuth particles and the formation temperature of the intermetallic compound should be lower than the curing temperature of the epoxy resin which is the base resin.

  If the melting temperature of the tin-bismuth particles and the formation temperature of the intermetallic compound are higher than the curing temperature of the epoxy resin, the base resin first cures and the melted tin-bismuth particles can not move to the surface of the copper particles. Therefore, the copper-tin layer which is an intermetallic compound can not be formed.

  Also, the content of tin / bismuth particles with respect to the total metal particles for forming the intermetallic compound may be 10 to 90 wt%.

  If the content of tin / bismuth particles is less than 10 wt%, the size of the intermetallic compound formed by reacting with the metal particles becomes excessively large, making it difficult to form an intermetallic compound in the groove of the main body, And it also becomes difficult to arrange the conductive connection portion on the third or fourth surface of the main body.

  Also, if the content of tin / bismuth particles exceeds 90 wt%, tin / bismuth will not react with each other to form an intermetallic compound, and there may be a problem that only the tin / bismuth particle size increases. .

  In addition, it is necessary to control the content of tin in tin / bismuth particles.

  In this embodiment, since the component that reacts with metal particles to form an intermetallic compound is tin, in order to secure such reactivity above a certain level, the content of Sn in Snx-Biy (x) However, it is preferable that it is 10 wt% or more of the whole metal particle.

  If the content (x) of tin is less than 10 wt% of the total metal particles, the ESR of the manufactured multilayer capacitor may be increased.

  In a multilayer capacitor in which a conductive resin layer is applied to the outer electrode, the ESR is totally affected by various resistances applied to the outer electrode.

  As such a resistance component, the resistance of the internal electrode, the contact resistance between the conductive resin layer and the internal electrode, the resistance of the conductive resin layer, the contact resistance between the first electrode layer and the conductive resin layer, and the first electrode The resistance of the layer can be mentioned.

  Here, the resistance of the internal electrode and the resistance of the first electrode layer are fixed values and do not fluctuate.

  According to the present embodiment, since there is no firing electrode layer between the external electrode and the main body, it is possible to eliminate the bending stress of the firing electrode layer that occurs when the conventional chip is bent, thereby lowering the process temperature. , It will be possible to prevent cracks that occur in the body.

  In addition, since the bonding strength of the external electrode is increased by the intermetallic compound, the bending strength of the multilayer capacitor can be further improved as compared with the embodiment in which the fired electrode layer is included at the outermost portion of the external electrode.

  Furthermore, the electrical connectivity between the internal electrode and the conductive resin layer is improved by the intermetallic compound, whereby the contact resistance can be reduced and the ESR of the multilayer capacitor can be further lowered.

  The external electrode of the conventional multilayer capacitor applies copper (Cu) paste to both ends of the main body where the internal electrode is exposed, and bakes to form an electrode layer, thereby preventing the dissolution of solder on the electrode layer. In the structure where a nickel (Ni) plating layer is formed for mounting, and a chip substrate is mounted on the nickel plating layer, a tin (Sn) plating layer is further formed to improve the wettability of the solder (solder). is there.

  At this time, the nickel plating layer, together with the tin plating layer, prevents the permeation of moisture from the outside, but due to the fine defects possessed by the nickel plating layer, the role of preventing the permeation of the plating solution and moisture can not be sufficiently exhibited.

  In the multilayer capacitor of this embodiment, a low melting point metal resin that is resistant to the penetration of the plating solution and external moisture is formed as a primary external electrode.

  The low melting point metal-resin electrode is excellent in electrical connectivity because it forms an intermetallic compound (IMC) with an internal electrode (Ni electrode) in a low temperature curing process by applying a low melting point metal.

  Further, by forming the IMC on the low melting point metal resin electrode, it is possible to suppress the penetration of the plating solution and the penetration of external moisture.

  Furthermore, in order to further improve the permeation prevention characteristics of the plating solution and moisture, a Cu electrode layer was formed by a plating process as a secondary external electrode.

  Since the Cu electrode layer formed by plating has a high degree of electrode compactness, the penetration preventing characteristics of the plating solution and moisture can be further improved as compared with the sintered Cu electrode layer.

  Next, a Ni plating layer for preventing dissolution of the solder and a Sn plating layer for improving the wettability of the solder are formed.

  Such an external electrode formation process can be performed at 250 degrees C or less, and the waterproof coating process for preventing permeation of a water | moisture content can be applied.

  In addition, by improving the penetration prevention characteristics of the plating solution and external moisture, it is possible to reduce the thickness of the primary external electrode which is a low melting point metal resin with respect to the existing fired Cu electrode, and to reduce the effective area and capacity of the chip. It can be improved.

  That is, according to the present embodiment, the primary electrode layer of the external electrode is a low melting point metal resin layer, the secondary electrode layer is a Cu electrode layer, the tertiary electrode layer is a Ni electrode layer, and the quaternary electrode layer is a Sn electrode layer. It is a thing.

Modified Example Referring to FIG. 11, the multilayer capacitor 100 ′ according to still another embodiment of the present invention has the moisture permeation preventing films 161 and 162 formed on the first and second surfaces 1 and 2 of the main body 110, respectively. .

  Here, for the structure similar to that of the above-described one embodiment, in order to avoid duplication, the specific description thereof is omitted, and the permeation prevention films 161 and 162 having a structure different from the above-described embodiment are shown. It demonstrates concretely, showing.

An organic layer or an inorganic layer such as parylene, Al ₂ O ₃ or SiO ₂ may be applied to the moisture permeation preventing films 161 and 162, such as dipping, coating, and It can be formed by PVD / CVD, ALD thin film deposition process, or the like.

  In this embodiment, the inner layer in contact with the third and fourth surfaces 3 and 4 of the main body 110 is formed as a conductive resin layer, and a low melting point metal which can be processed at a low temperature is applied to the conductive resin layer. It also becomes possible to apply an organic layer which can not be used at high process temperatures as a moisture permeation preventing film.

  Such moisture permeation preventing films 161 and 162 have an effect of being able to greatly improve the reliability.

Method of Manufacturing Multilayer Capacitor Hereinafter, a method of manufacturing a multilayer capacitor according to an embodiment of the present invention will be specifically described, but the present invention is not limited thereto, and the multilayer capacitor of this embodiment In the description of the manufacturing method, the description overlapping with the description of the above-described multilayer capacitor is omitted.

In the method of manufacturing the multilayer capacitor according to the present embodiment, first, a slurry formed of powder such as barium titanate (BaTiO ₃ ) is coated on a carrier film and dried to form a plurality of ceramic greens. By providing the sheet, the dielectric layer and the cover can be manufactured and formed.

  The ceramic green sheet is a slurry prepared by mixing a ceramic powder, a binder and a solvent, and the slurry is formed into a sheet having a thickness of several μm by a doctor blade method or the like.

  Next, a conductive paste for an internal electrode containing a conductive metal such as copper is applied onto the green sheet by a screen printing method or the like to form an internal electrode.

  Thereafter, a plurality of green sheets on which the internal electrodes are printed are laminated, and a plurality of green sheets on which the internal electrodes are not printed are laminated on the upper and lower surfaces of the laminate, and then firing can be performed. At this time, the internal electrodes may be formed of first and second internal electrodes having different polarities.

  That is, the body includes a dielectric layer, first and second inner electrodes, and a cover. The dielectric layer is formed by firing a green sheet on which the internal electrode is printed, and the cover is formed by firing a green sheet on which the internal electrode is not printed.

  Further, the main body is connected to the first and second surfaces facing each other, the first and second surfaces, the third and fourth surfaces facing each other, the first and second surfaces, and the third And the fourth surface, and includes the fifth and sixth surfaces facing each other, and the third and fourth surfaces are provided with upper and lower ends so that one end portions of the first and second internal electrodes are exposed, respectively A plurality of first and second grooves are formed between the dielectric layers disposed in the.

  Next, a conductive resin composition containing metal particles, a thermosetting resin, and a low melting point metal having a melting point lower than that of the thermosetting resin is provided.

  The conductive resin composition may be prepared, for example, by mixing copper particles which are metal particles, tin / bismuth particles which is a low melting point metal, an oxide film removing agent, and an epoxy resin of 4 to 15 wt%. -It can manufacture by disperse | distributing using (roll mill).

  And applying the conductive resin composition to the third and fourth surfaces of the main body, and forming a conductive resin layer having a conductive connection portion surrounding the low melting point metal which has been dried, cured and melted. it can.

  At this time, in the step of forming the conductive resin layer, the metal particles contained in the thermosetting resin and the oxide film on the surface of the low melting point metal are removed, and then the metal particles and the oxide film from which the oxide film has been removed The low melting point metal from which is removed reacts to form a conductive connection, and the low melting point metal flows into the first and second grooves of the main body while having fluidity, to form the first and second grooves. It is possible to form an intermetallic compound made of copper-tin or the like in contact with one end of the first and second internal electrodes in the groove.

  In this case, when a part of the metal particles remains without completely reacting with the low melting point metal, the remaining metal particles are present in the conductive resin layer in a state covered by the molten low melting point metal. can do.

  Also, the metal particles may be copper or at least one or more of nickel, silver, copper coated with silver, copper coated with tin, but the present invention is not limited thereto. It is not something to be done.

  Furthermore, the low melting point metal may be at least one of Sn / Bi, Sn-Pb, Sn-Cu, Sn-Ag, and Sn-Ag-Cu, but the present invention is limited thereto. It is not a thing.

  Although the said thermosetting resin can contain an epoxy resin as an example, this invention is not limited to this, For example, bisphenol A resin, a glycol epoxy resin, novolak epoxy resin, or these derivatives. It may be a resin having a small molecular weight and being liquid at normal temperature.

  Then, a first electrode layer is formed on the conductive resin layer to be electrically connected.

  The first electrode layer can be formed by applying a paste containing a conductive metal and glass and then baking it.

  At this time, the conductive metal is not particularly limited, and may be, for example, one or more selected from the group consisting of copper, nickel, palladium, gold, silver, and alloys thereof.

  Further, the above-mentioned glass is not particularly limited, but a substance having the same composition as the glass used for producing the external electrode of a general multilayer capacitor may be used.

  The method may further include forming a second electrode layer on the first electrode layer. The second electrode layer may be formed by plating, and may include, for example, a nickel plating layer and a tin plating layer further formed thereon.

  On the other hand, before applying the conductive resin composition to the main body, a step of forming a moisture permeation preventing film on the first and second surfaces of the main body may be performed.

  Although the embodiments of the present invention have been described in detail, the scope of the present invention is not limited thereto, and various modifications and changes may be made without departing from the technical concept of the present invention described in the claims. It will be apparent to those skilled in the art that this is possible.

100, 100 'multilayer capacitor 110 main body 111 dielectric layer 112, 113 upper and lower cover 121, 122 first and second inner electrode 130, 140 first and second outer electrode 131, 141 conductive resin layer 132, 142 1st electrode layer 133, 143 nickel (Ni) plating layer 134, 144 tin (Sn) plating layer 131a metal particle 131b conductive connection part 131c base resin 150 intermetallic compound 161, 162 moisture permeation preventing film

Claims (40)

First and second surfaces facing each other, including the plurality of dielectric layers and the plurality of first and second inner electrodes alternately arranged via the plurality of dielectric layers, and the first and second surfaces Connected, including third and fourth surfaces facing each other, connected with the first and second surfaces, and connected with the third and fourth surfaces, and including fifth and sixth surfaces facing each other, A main body in which a plurality of first and second grooves are formed between upper and lower dielectric layers on the third and fourth surfaces such that one end of each of the first and second internal electrodes is exposed. When,
Intermetallic compounds disposed in the first and second grooves and connected to one ends of the first and second internal electrodes, respectively;
First and second external electrodes disposed respectively on the third and fourth surfaces of the body;
The first and second external electrodes are
A conductive resin layer disposed on the third and fourth surfaces of the main body and including a plurality of metal particles, a conductive connection portion surrounding the plurality of metal particles and in contact with the intermetallic compound, and a base resin;
A first electrode layer disposed on the conductive resin layer and in contact with the conductive connection portion;
Multilayer capacitors.   The multilayer capacitor according to claim 1, wherein the conductive connection portion has a melting point lower than a curing temperature of the base resin.   The multilayer capacitor according to claim 2, wherein the melting point of the conductive connection portion is 300 ° C. or less.   The multilayer capacitor according to any one of claims 1 to 3, wherein the conductive connection portion includes two or more selected from tin, lead, indium, copper, silver, and bismuth.   The conductive resin layer according to any one of claims 1 to 4, wherein the plurality of metal particles include at least one of copper, nickel, silver, copper coated with silver, and copper coated with tin. The multilayer capacitor according to the item.   The multilayer capacitor according to any one of claims 1 to 5, wherein the internal electrode comprises nickel and the intermetallic compound comprises nickel-tin (Ni-Sn).   The multilayer capacitor according to any one of claims 1 to 6, wherein the internal electrode comprises any one of nickel, copper, palladium, or an alloy thereof.   The conductive resin layer according to any one of claims 1 to 7, wherein the plurality of metal particles are one of a spherical shape, a flake shape, and a mixed shape of a spherical shape and a flake shape. The multilayer capacitor of description.   The multilayer capacitor according to any one of claims 1 to 8, further comprising a moisture permeation preventing film formed on each of the first and second surfaces of the main body.   The external electrode includes a connection portion respectively formed on the third and fourth surfaces of the main body, and a portion of the first and second surfaces and a portion of the fifth and sixth surfaces of the main body from the connection portion. The multilayer capacitor according to any one of claims 1 to 9, wherein each includes an extended band portion.   The multilayer capacitor according to any one of claims 1 to 10, wherein the first electrode layer contains any of copper, tin, nickel, palladium, gold, or an alloy thereof.   The multilayer capacitor according to any one of claims 1 to 11, wherein the first and second outer electrodes further include a second electrode layer disposed on the first electrode layer.   The multilayer capacitor according to claim 12, wherein the second electrode layer includes a nickel plating layer and a tin plating layer sequentially formed on the first electrode layer.   The multilayer capacitor according to any one of claims 1 to 13, wherein upper and lower covers having the same material and configuration as the dielectric layer are disposed on upper and lower surfaces of the body, respectively. First and second surfaces facing each other, including the plurality of dielectric layers and the plurality of first and second inner electrodes alternately arranged via the plurality of dielectric layers, and the first and second surfaces Connected, including third and fourth surfaces facing each other, connected with the first and second surfaces, and connected with the third and fourth surfaces, and including fifth and sixth surfaces facing each other, A main body in which one end of first and second internal electrodes are exposed from the third and fourth surfaces, respectively;
Intermetallic compounds respectively connected to one ends of the first and second internal electrodes;
A moisture permeation preventing film formed on each of the first and second surfaces of the main body;
First and second external electrodes disposed respectively on the third and fourth surfaces of the body;
The first and second external electrodes are
A conductive resin layer disposed on the third and fourth surfaces of the main body and including a plurality of metal particles, a conductive connection portion surrounding the plurality of metal particles and in contact with the intermetallic compound, and a base resin;
A first electrode layer disposed on the conductive resin layer and in contact with the conductive connection portion;
Multilayer capacitors.   The multilayer capacitor according to claim 15, wherein the conductive connection portion has a melting point lower than a curing temperature of the base resin.   The multilayer capacitor according to claim 16, wherein the melting point of the conductive connection portion is 300 ° C. or less.   The multilayer capacitor according to any one of claims 15 to 17, wherein the conductive connection portion includes two or more selected from tin, lead, indium, copper, silver, and bismuth.   The conductive resin layer according to any one of claims 15 to 18, wherein the plurality of metal particles include at least one of copper, nickel, silver, copper coated with silver, and copper coated with tin. The multilayer capacitor according to the item.   The multilayer capacitor according to any one of claims 15 to 19, wherein the internal electrode comprises nickel and the intermetallic compound comprises nickel-tin (Ni-Sn).   21. The multilayer capacitor according to any one of claims 15 to 20, wherein the inner electrode comprises any of nickel, copper, palladium or an alloy thereof.   22. The conductive resin layer according to any one of claims 15 to 21, wherein the plurality of metal particles are one of spheres, flakes, and a mixture of spheres and flakes. The multilayer capacitor of description.   The external electrode includes a connection portion respectively formed on the third and fourth surfaces of the main body, and a portion of the first and second surfaces and a portion of the fifth and sixth surfaces of the main body from the connection portion. The multilayer capacitor according to any one of claims 15 to 22, wherein the multilayer capacitors respectively include extended band portions.   The multilayer capacitor according to any one of claims 15 to 23, wherein the first electrode layer contains any of copper, tin, nickel, palladium, gold, or an alloy thereof.   The multilayer capacitor according to any one of claims 15 to 24, wherein the first and second outer electrodes further include a second electrode layer disposed on the first electrode layer.   The multilayer capacitor according to claim 25, wherein the second electrode layer includes a nickel plating layer and a tin plating layer formed by being sequentially stacked on the first electrode layer.   27. The multilayer capacitor according to any one of claims 15 to 26, wherein upper and lower covers having the same material and configuration as the dielectric layer are disposed on upper and lower surfaces of the body, respectively. First and second surfaces facing each other, including the plurality of dielectric layers and the plurality of first and second inner electrodes alternately arranged via the plurality of dielectric layers, and the first and second surfaces Connected, including third and fourth surfaces facing each other, connected with the first and second surfaces, and connected with the third and fourth surfaces, and including fifth and sixth surfaces facing each other, A main body in which one end of first and second internal electrodes are exposed from the third and fourth surfaces, respectively;
Intermetallic compounds respectively connected to one ends of the first and second internal electrodes;
First and second external electrodes disposed respectively on the third and fourth surfaces of the body;
The first and second external electrodes are
A conductive resin layer disposed on the third and fourth surfaces of the main body and including a plurality of metal particles, a conductive connection portion surrounding the plurality of metal particles and in contact with the intermetallic compound, and a base resin;
A first electrode layer disposed on the conductive resin layer and in contact with the conductive connection portion;
Including
The multilayer capacitor, wherein the first electrode layer is a copper plating layer.   The multilayer capacitor according to claim 28, wherein the conductive connection portion has a melting point lower than a curing temperature of the base resin.   The multilayer capacitor according to claim 29, wherein the melting point of the conductive connection portion is 300 ° C or less.   31. The multilayer capacitor according to any one of claims 28 to 30, wherein the conductive connection includes two or more selected from tin, lead, indium, copper, silver, and bismuth.   The conductive resin layer according to any one of claims 28 to 31, wherein the plurality of metal particles include at least one of copper, nickel, silver, copper coated with silver, and copper coated with tin. The multilayer capacitor according to the item.   The multilayer capacitor according to any one of claims 28 to 32, wherein the internal electrode comprises nickel and the intermetallic compound comprises nickel-tin (Ni-Sn).   34. The multilayer capacitor according to any one of claims 28 to 33, wherein the inner electrode comprises any of nickel, copper, palladium or an alloy thereof.   35. The conductive resin layer according to any one of claims 28 to 34, wherein the plurality of metal particles are in the form of spheres, flakes, or a mixture of spheres and flakes. Multilayer capacitors.   36. The multilayer capacitor according to any one of claims 28 to 35, further comprising a moisture permeation preventing film formed on each of the first and second surfaces of the main body.   The external electrode includes a connection portion respectively formed on the third and fourth surfaces of the main body, and a portion of the first and second surfaces and a portion of the fifth and sixth surfaces of the main body from the connection portion 37. The multilayer capacitor according to any one of claims 28 to 36, wherein each includes an extended band portion.   The multilayer capacitor according to any one of claims 28 to 37, wherein the first and second outer electrodes further include a second electrode layer disposed on the first electrode layer.   The multilayer capacitor according to claim 38, wherein the second electrode layer includes a nickel plating layer and a tin plating layer sequentially formed on the first electrode layer.   40. The multilayer capacitor according to any one of claims 28 to 39, wherein upper and lower covers having the same material and configuration as the dielectric layer are respectively disposed on upper and lower surfaces of the body.