JP4163637B2 - Electronic component, multilayer ceramic capacitor, and method for manufacturing the same - Google Patents

Description

  The present invention relates to an electronic component such as a multilayer ceramic capacitor and a method for manufacturing the same.

  A multilayer ceramic capacitor as an example of an electronic component includes an element body having a multilayer structure in which a plurality of dielectric layers and internal electrode layers are alternately arranged, and a pair of external terminal electrodes formed at both ends of the element body. Composed.

  This multilayer ceramic capacitor is manufactured by first laminating a plurality of pre-firing dielectric layers and pre-firing internal electrode layers alternately in a necessary number to produce a pre-firing element body, and then firing the pre-firing element body. It is manufactured by forming a pair of external terminal electrodes at both ends.

  A ceramic green sheet is used as the dielectric layer before firing, and an internal electrode paste or a metal thin film having a predetermined pattern is used as the internal electrode layer before firing.

  The ceramic green sheet can be manufactured by a sheet method or a stretching method. The sheet method is a method in which a dielectric coating containing a dielectric powder, a binder, a plasticizer, an organic solvent, and the like is applied on a carrier sheet such as PET using a doctor blade method, and dried by heating. . The stretching method is a method in which a film-like molded body obtained by extrusion molding a dielectric suspension in which a dielectric powder and a binder are mixed in a solvent is produced by biaxial stretching.

  The internal electrode paste having a predetermined pattern is manufactured by a printing method. The printing method is a method in which a conductive material containing a metal such as Pd, Ag-Pd, Ni, and a conductive paint containing a binder, an organic solvent, and the like are applied and formed on a ceramic green sheet in a predetermined pattern. The metal thin film having a predetermined pattern is manufactured by a thin film method such as sputtering.

  Thus, when manufacturing the multilayer ceramic capacitor, the pre-firing dielectric layer and the pre-firing internal electrode layer are fired simultaneously. Therefore, the conductive material contained in the internal electrode layer before firing has a melting point higher than the sintering temperature of the dielectric powder contained in the dielectric layer before firing, does not react with the dielectric powder, and the dielectric after firing. It is required not to diffuse into the body layer.

  Conventionally, in order to satisfy these requirements, noble metals such as Pt and Pd have been used for the conductive material contained in the internal electrode layer before firing. However, the noble metal itself is expensive, and as a result, there is a disadvantage that the finally obtained multilayer ceramic capacitor is expensive. Therefore, conventionally, the sintering temperature of the dielectric powder is lowered to 900 to 1100 ° C., and an Ag—Pd alloy is used as the conductive material included in the internal electrode layer before firing, or an inexpensive base metal such as Ni is used. Is widely known.

  By the way, in recent years, with the miniaturization of various electronic devices, miniaturization and large capacity of the multilayer ceramic capacitor mounted inside the electronic device are progressing. In order to reduce the size and increase the capacity of the multilayer ceramic capacitor, it is required to stack not only a dielectric layer but also a thin internal electrode layer with few defects.

  However, when Ni is used for the conductive material contained in the internal electrode layer before firing, this Ni has a lower melting point than the dielectric powder contained in the dielectric layer before firing. For this reason, when these were baked simultaneously, the big difference had arisen between both sintering temperature. If there is a large difference in sintering temperature, sintering at a high temperature will cause cracking and peeling of the internal electrode layer, while sintering at a low temperature may cause firing failure of the dielectric powder.

  Further, when the thickness of the internal electrode layer before firing is reduced, Ni particles contained in the conductive material are spheroidized by grain growth during firing in a reducing atmosphere, and adjacent Ni particles that were connected before firing The space | interval between them opens and a void | hole is produced in arbitrary places, As a result, it becomes difficult to form an internal electrode layer continuously after baking. When the internal electrode layer is not continuous after firing, there is a problem that the capacitance of the multilayer ceramic capacitor is reduced.

  By the way, the following Patent Document 1 shows a method of alloying the internal electrode layer in order to prevent the internal electrode from being interrupted. However, in Patent Document 1, since it is difficult to control the alloy by the thin film formation method, the internal electrode layer is prepared as a metal multilayer film before firing and alloyed through a firing step.

JP-A-3-126206

  However, in this patent document 1, when using an internal electrode whose main component is nickel, alloying with any kind of metal suppresses the grain growth of nickel particles in the firing stage, and makes it spherical. There is no disclosure about whether electrode breakage can be prevented. Depending on the composition constituting each multilayer metal film, the sintering temperature is lowered, and the grain growth of nickel particles in the firing stage cannot be suppressed.

  In addition, when the metal film in contact with the ceramic is poor in wettability and adhesion with the ceramic as a structure of each multilayer metal film, conversely, spheroidization and interruption occur, and the capacitance as a capacitor decreases.

  The present invention has been made in view of such a situation, and in particular, even when the thickness of the internal electrode layer is reduced, the grain growth of Ni particles in the firing stage is suppressed, and spheroidization and electrode breakage are effectively prevented. An object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor that can effectively suppress a decrease in capacitance and a method for manufacturing the same.

In order to achieve the above object, an electronic component according to the present invention includes:
An electronic component having an internal electrode layer and a dielectric layer,
The internal electrode layer is
A main conductive layer mainly composed of nickel;
A sub-conductive layer formed between the main conductive layer and the dielectric layer;
The sub conductive layer is a metal layer or alloy layer having at least one element selected from ruthenium (Ru), rhodium (Rh), rhenium (Re), platinum (Pt), iridium (Ir) and osmium (Os). It is characterized by being.

  In the present invention, the electronic component is not particularly limited, and examples thereof include a multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, and other surface mount (SMD) chip type electronic components.

The multilayer ceramic capacitor according to the present invention is
A multilayer ceramic capacitor having an element body in which internal electrode layers and dielectric layers are alternately laminated,
The internal electrode layer is
A main conductive layer mainly composed of nickel;
A sub-conductive layer formed between the main conductive layer and the dielectric layer;
The sub-conductive layer is a metal layer having as a main component at least one element selected from ruthenium (Ru), rhodium (Rh), rhenium (Re), platinum (Pt), iridium (Ir) and osmium (Os). Or it is an alloy layer, It is characterized by the above-mentioned.

  Ru, Rh, Re, Pt, Ir and Os are noble metals having a melting point higher than that of Ni. Further, the sub-conductive layer mainly composed of these metals or alloys is excellent in wettability and adhesion with the dielectric layer. Therefore, by forming this sub-conductive layer between the main conductive layer and the dielectric layer, the grain growth of Ni particles in the firing stage is suppressed, spheroidization, electrode breakage, etc. are effectively prevented, and static electricity is prevented. A decrease in electric capacity can be effectively suppressed. Further, delamination between the internal electrode layer and the dielectric layer can be prevented. Furthermore, there is no firing failure of the dielectric powder.

  In the present invention, the sub conductive layer may be formed on at least one side of the main conductive layer. Preferably, the main conductive layer is sandwiched between a pair of sub conductive layers, and the internal The electrode layer has a laminated structure of three or more layers. By doing so, the main conductive layer is prevented from coming into contact with the dielectric layer from both sides, and the effect of the present invention is enhanced.

  In the present invention, an alloy layer of a main component metal constituting the main conductive layer and a main component metal constituting the sub conductive layer may be formed between the main conductive layer and the sub conductive layer. good. Even if the alloy layer of the main conductive layer and the sub conductive layer is formed, the effect of the present invention is not changed. However, it is preferable that the sub conductive layer is not completely alloyed with the main conductive layer and the sub conductive layer remains.

  Preferably, the dielectric layer is made of a dielectric material that can be fired in a reducing atmosphere. Since the main conductive layer in the internal electrode layer is mainly composed of nickel, the dielectric layer is preferably made of a dielectric material that can be fired in a reducing atmosphere so as not to be oxidized during simultaneous firing.

  Preferably, the thickness of the sub-conductive layer is greater than 0 μm and 0.1 μm or less, more preferably 0 μm (not including 0) to 0.08 μm. Preferably, the main conductive layer has a thickness of 0.1 μm to 1.0 μm. Further, preferably, the thickness of the sub-conductive layer is preferably 0 (0 is not included) to 30%, more preferably 0 (0 is not included) to 20% of the thickness of the main conductive layer. It is. The total thickness of the internal electrode layers including the main conductive layer and the sub conductive layer is preferably 1 μm or less, and more preferably 0.1 to 0.5 μm. If the thickness of the sub conductive layer is too thin, the effect of the present invention is small, and if the thickness of the sub conductive layer is too large relative to the thickness of the main conductive layer, in order to reduce the total thickness of the internal electrode layer, The thickness of the main conductive layer becomes too thin, which is not preferable from the viewpoint of reducing resistance.

  Preferably, the crystallite size in the main conductive layer and / or sub conductive layer is 10 to 100 nm. If the crystallite size is too small, problems such as spheroidization and breakage of nickel particles tend to occur, and if it is too large, the film thickness tends to vary.

An electronic component manufacturing method according to the present invention includes:
A method of manufacturing an electronic component having an internal electrode layer and a dielectric layer,
Subconductivity composed of a metal layer or alloy layer having at least one element selected from ruthenium (Ru), rhodium (Rh), rhenium (Re), platinum (Pt), iridium (Ir) and osmium (Os) Forming a layer;
Laminating the sub-conductive layer to form a main conductive layer mainly composed of nickel;
Laminating the internal electrode layer having the sub conductive layer and the main conductive layer with a green sheet to be a dielectric layer after firing;
Firing a laminate of the green sheet and the internal electrode layer.

The method for producing a multilayer ceramic capacitor according to the present invention comprises:
A method of manufacturing a multilayer ceramic capacitor having an element body in which internal electrode layers and dielectric layers are alternately stacked,
Subconductivity composed of a metal layer or alloy layer having at least one element selected from ruthenium (Ru), rhodium (Rh), rhenium (Re), platinum (Pt), iridium (Ir) and osmium (Os) Forming a layer;
Laminating the sub-conductive layer to form a main conductive layer mainly composed of nickel;
Laminating the internal electrode layer having the sub conductive layer and the main conductive layer alternately with a green sheet that becomes a dielectric layer after firing;
Firing a laminate of the green sheet and the internal electrode layer.

  According to the method of the present invention, the electronic component and the multilayer ceramic capacitor according to the present invention can be efficiently manufactured.

  Preferably, the internal electrode layer is laminated on the green sheet so that the sub conductive layer is located between the main conductive layer and the green sheet in the internal electrode layer. The effect of the present invention is improved by positioning the sub conductive layer between the main conductive layer and the green sheet.

  An adhesive layer may be interposed between the internal electrode layer and the green sheet. When the green sheet and the internal electrode layer are thinned, it tends to be difficult to form the internal electrode layer on the surface of the green sheet by a normal printing method or the like. It is preferable to be laminated on the surface. In that case, it tends to be difficult to bond the internal electrode layer and the green sheet, and these are preferably bonded by the adhesive layer. Note that the adhesive layer is removed by a binder removal treatment and / or a firing treatment of the laminate.

  Preferably, the internal electrode layer is formed on a support sheet, and then peeled from the support sheet and laminated on the green sheet. Preferably, the sub conductive layer is formed by a thin film forming method (sputtering method, plating method, vapor deposition method, etc.), and the main conductive layer is formed by a printing method or a thin film forming method. When the green sheet and internal electrode layer are made thinner, it tends to be difficult to form the internal electrode layer directly on the surface of the green sheet. It is preferable to form the film and transfer it to a green sheet thereafter.

  In addition, both the sub conductive layer and the main conductive layer are manufactured not only by the thin film forming method (sputtering method, plating method, vapor deposition method, etc.), but the sub conductive layer is manufactured by the thin film forming method, and the Ni conductive paste is used. The main conductive layer may be formed by screen printing. Even in this case, the grain growth of Ni particles in the firing process is similarly suppressed, and the capacity reduction can be effectively suppressed.

Preferably, the laminate of the internal electrode layer and the green sheet is fired at a temperature of 900 ° C. or higher and lower than 1000 ° C. in an atmosphere having an oxygen partial pressure of 10 ⁻¹⁴ to 10 ⁻⁶ Pa. By setting the main conductive layer and the sub conductive layer in the internal electrode layer within the above-mentioned film thickness range, and firing under such conditions, the main conductive layer and the sub conductive layer are not completely alloyed, Spheroidization due to grain growth of particles can be suppressed. If the firing temperature is less than 900 ° C., densification of the dielectric layer after sintering tends to be insufficient and the capacitance tends to be insufficient, and if it is 1000 ° C. or more, the dielectric layer becomes over-fired, There is a tendency that the capacity change with time when a DC electric field is applied increases.

Preferably, after firing the laminate, annealing is performed at a temperature of 950 ° C. or lower in an atmosphere having an oxygen partial pressure of 10 ^{−3 to} 100 Pa. After the firing, annealing is performed under specific annealing conditions, so that the dielectric layer can be re-oxidized, the dielectric layer can be prevented from becoming a semiconductor, and high insulation resistance can be obtained.

  The material and manufacturing method of the green sheet that can be used in the present invention are not particularly limited, and the ceramic green sheet formed by the doctor blade method, the porous ceramic obtained by biaxially stretching the extruded film It may be a green sheet or the like.

  According to the present invention, even when each thickness of the internal electrode layer is thinned, the grain growth of Ni particles in the firing stage is suppressed, spheroidization, electrode breakage is effectively prevented, and the capacitance is reduced. It is possible to provide an electronic component such as a multilayer ceramic capacitor and a method for manufacturing the same.

Hereinafter, the present invention will be described based on embodiments shown in the drawings. Here, FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of essential parts of the internal electrode layer shown in FIG. 1, and FIGS. 3 (A) to 3 (C) 4 (A) to 4 (C) are cross-sectional views showing the main part of the method for transferring the internal electrode layer film.
First, an overall configuration of a multilayer ceramic capacitor will be described as an embodiment of an electronic component according to the present invention.
As shown in FIG. 1, the multilayer ceramic capacitor 2 according to the present embodiment includes a capacitor body 4, a first terminal electrode 6, and a second terminal electrode 8. The capacitor body 4 includes dielectric layers 10 and internal electrode layers 12, and the internal electrode layers 12 are alternately stacked between the dielectric layers 10. One internal electrode layer 12 that is alternately stacked is electrically connected to the inside of the first terminal electrode 6 that is formed outside the first end 4 a of the capacitor body 4. Further, the other internal electrode layers 12 stacked alternately are electrically connected to the inside of the second terminal electrode 8 formed outside the second end portion 4 b of the capacitor body 4.

  In this embodiment, as shown in FIG. 2, each internal electrode layer 12 includes a main conductive layer 40 and a pair of sub conductive layers 42 stacked on both sides thereof. In the present invention, either one of the sub conductive layers 42 may be omitted.

  The main conductive layer 40 is composed of a metal layer mainly composed of nickel or an alloy layer with another metal mainly composed of nickel. The proportion of nickel in the main conductive layer 40 is preferably 99 to 100% by mass, more preferably 99.5 to 100% by mass, with the main conductive layer 40 being 100% by mass. If the proportion of nickel as the main component is too small, there is a tendency that electrical resistance increases, spheroidization due to grain growth of nickel particles during firing, electrode breakage, and the like are likely to occur.

  In addition, as a metal as a subcomponent which can comprise nickel and the alloy in the main conductive layer 40, Ta, Mo, Zr, Nb, W, Co, Fe, Cu etc. are illustrated, for example.

  The sub-conductive layer 42 is a metal having as a main component at least one noble metal element selected from ruthenium (Ru), rhodium (Rh), rhenium (Re), platinum (Pt), iridium (Ir) and osmium (Os). It consists of a layer or an alloy layer. The ratio of these elements contained as the main component is preferably 99 to 100% by mass, more preferably 99.5 to 100% by mass, with the sub-conductive layer 42 being 100% by mass. If the ratio of the noble metal element as the main component is too small, the effect of suppressing the grain growth of Ni particles in the main conductive layer 40 in the firing stage tends to be reduced. Examples of components that may be contained in the sub-conductive layer other than the main component include Cu, Co, Fe, Ta, Nb, W, Zr, Au, and Pd.

  Between the main conductive layer 40 and the sub conductive layer 42, an alloy layer of main components constituting these layers may be formed. The main conductive layer 40 and / or the sub conductive layer 42 may contain various trace components such as P, S, and C in an amount of about 0.1 mol% or less.

  Preferably, the thickness tb of the sub-conductive layer 42 is greater than 0 μm and 0.1 μm or less, more preferably 0 μm (not including 0) to 0.08 μm. Preferably, the thickness ta of the main conductive layer 40 is not less than 0.1 μm and not more than 1.0 μm. Further, preferably, the thickness tb of the sub conductive layer 42 is preferably greater than 0% and not greater than 30%, more preferably greater than 0% and not greater than 20%, as compared to the thickness of the main conductive layer ta. Further, the total thickness of the internal electrode layer 12 including the main conductive layer 40 and the pair of sub conductive layers 42 is preferably 1 μm or less, and preferably 0.1 μm or more and 0.5 μm or less. If the thickness of the sub-conductive layer 42 is too thin, the effect of the present invention is small. If the thickness of the sub-conductive layer 42 is too large with respect to the thickness of the main conductive layer 40, the total thickness of the internal electrode layers is reduced. In this case, the thickness of the main conductive layer 40 becomes too thin, which is not preferable in terms of resistance reduction.

  The pair of sub conductive layers 42 in the internal electrode layer 12 preferably have the same film thickness, but may have different film thicknesses. The pair of sub-conductive layers 42 are preferably made of the same material because of simplification of the manufacturing process, but may be made of different materials.

  The internal electrode layer 12 configured as described above is formed by transferring the internal electrode layer film 12a to the ceramic green sheet 10a as shown in FIGS. . The internal electrode layer 12 is thicker than the internal electrode layer film 12a by the amount of horizontal contraction caused by firing.

  The material of the dielectric layer 10 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. The dielectric layer 10 is preferably made of a dielectric material that can be fired in a reducing atmosphere.

  The thickness of each dielectric layer 10 is not particularly limited, but is generally several μm to several hundred μm. In particular, in this embodiment, the thickness is preferably 5 μm or less, more preferably 3 μm or less.

  The material of the terminal electrodes 6 and 8 is not particularly limited, but usually copper, copper alloy, nickel, nickel alloy, or the like is used, but silver, silver-palladium alloy, or the like can also be used. The thickness of the terminal electrodes 6 and 8 is not particularly limited, but is usually about 10 to 50 μm.

  The shape and size of the multilayer ceramic capacitor 2 may be appropriately determined according to the purpose and application. When the multilayer ceramic capacitor 2 has a rectangular parallelepiped shape, it is usually vertical (0.6 to 5.6 mm, preferably 0.6 to 3.2 mm) × horizontal (0.3 to 5.0 mm, preferably 0.3 to 1.6 mm) × thickness (0.1 to 1.9 mm, preferably 0.3 to 1.6 mm).

  Next, an example of a method for manufacturing the multilayer ceramic capacitor 2 will be described.

First, a dielectric paste is prepared in order to manufacture a ceramic green sheet that will form the dielectric layer 10 shown in FIG. 1 after firing.
The dielectric paste is usually composed of an organic solvent-based paste obtained by kneading a dielectric material and an organic vehicle, or an aqueous paste.

  As the dielectric material, various compounds to be complex oxides and oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like are appropriately selected and used by mixing. The dielectric material is usually used as a powder having an average particle size of about 0.1 to 3.0 μm. In order to form a very thin green sheet, it is desirable to use a powder finer than the thickness of the green sheet.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used in the organic vehicle is not particularly limited, and various ordinary binders such as ethyl cellulose, polyvinyl butyral, and acrylic resin are used, but a butyral resin such as polyvinyl butyral is preferably used.

  Moreover, the organic solvent used for the organic vehicle is not particularly limited, and organic solvents such as terpineol, butyl carbitol, acetone, and toluene are used. Further, the vehicle in the aqueous paste is obtained by dissolving a water-soluble binder in water. The water-soluble binder is not particularly limited, and polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, water-soluble acrylic resin, emulsion and the like are used. The content of each component in the dielectric paste is not particularly limited, and the normal content, for example, the binder may be about 1 to 5% by mass, and the solvent (or water) may be about 10 to 50% by mass.

  The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, glass frit, insulators and the like as required. However, the total content of these is preferably 10% by mass or less. When a butyral resin is used as the binder resin, the plasticizer preferably has a content of 25 to 100 parts by mass with respect to 100 parts by mass of the binder resin. If the amount of the plasticizer is too small, the green sheet tends to be brittle. If the amount is too large, the plasticizer oozes out and is difficult to handle.

  Next, using the dielectric paste, by a doctor blade method or the like, as shown in FIG. 4A, on the carrier sheet 30 as the second support sheet, preferably 0.5 to 30 μm, more preferably The green sheet 10a is formed with a thickness of about 0.5 to 10 μm. The green sheet 10 a is dried after being formed on the carrier sheet 30. The drying temperature of the green sheet 10a is preferably 50 to 100 ° C., and the drying time is preferably 1 to 5 minutes.

  Next, separately from the carrier sheet 30, as shown in FIG. 3A, a carrier sheet 20 as a first support sheet is prepared, and a release layer 22 is formed thereon. Next, an internal electrode layer film 12 a that will form the internal electrode layer 12 after firing is formed in a predetermined pattern on the surface of the release layer 22.

  The internal electrode layer film 12a is formed of a laminated film in which the film 40a that forms the main conductive layer 40 is sandwiched between the films 42a that form the sub conductive layer 42.

  The total thickness t1 of the formed internal electrode layer film 12a is preferably about 0.1 to 1 μm, more preferably about 0.1 to 0.5 μm.

  The method for forming the internal electrode layer film 12a is not particularly limited, and examples thereof include a thin film method and a printing method. Hereinafter, the case of forming by the thin film method and the case of forming by the printing method will be described separately.

Thin Film Method First, the case where the internal electrode layer film 12a is formed by the thin film method will be described.

  Examples of the thin film method include plating, vapor deposition, and sputtering. For example, when the internal electrode layer film 12a is formed on the surface of the release layer 22 by sputtering, it is performed as follows.

  First, as the sputtering target material, two types of materials for forming the above-described film 42a and film 40a are prepared. In this embodiment, sputtering is first performed using a target for forming the film 42a, then sputtering is performed using a target for forming the film 40a, and then the film 42a is formed. Sputtering is performed using a target to form a three-layer film. These sputterings are preferably performed continuously in the same chamber, but may be performed in separate chambers.

As the sputtering conditions, the ultimate vacuum is preferably 10 ⁻² Pa or less, more preferably 10 ⁻³ Pa or less, and the Ar gas introduction pressure is preferably 0.1 to ² Pa, more preferably 0.3 to 0.8 Pa. The output is preferably 50 to 400 W, more preferably 100 to 300 W, and the sputtering temperature is preferably 20 to 150 ° C., more preferably 20 to 120 ° C.

Printing will be explained a case of forming the internal electrode layer film 12a by the printing method.

  Examples of the printing method include screen printing. When the internal electrode layer conductive paste film as the internal electrode layer film 12a is formed on the surface of the release layer 22 by the screen printing method, which is a kind of printing method, the following is performed.

  First, metal powder or alloy powder for forming the film 40a and the film 42a is prepared. The average particle size of these powders is preferably 0.01 to 0.4 μm (more preferably 0.05 to 0.2 μm). Each metal powder or alloy powder is kneaded with an organic vehicle to form a paste, thereby obtaining a conductive paste for forming the respective films 40a and 42a. The organic vehicle can be made of the same material as in the dielectric paste. By sequentially forming the obtained conductive paste in a predetermined pattern on the surface of the release layer 22, the internal electrode layer film 12 a having a predetermined pattern of a three-layer structure can be obtained.

  Next, separately from the carrier sheets 20 and 30, as shown in FIG. 3A, an adhesive layer transfer sheet in which an adhesive layer 28 is formed on the surface of a carrier sheet 26 as a third support sheet. prepare. The carrier sheet 26 is composed of a sheet similar to the carrier sheets 20 and 30.

  Next, in order to form an adhesive layer on the surface of the internal electrode layer film 12a shown in FIG. 3A, a transfer method is employed in this embodiment. That is, as shown in FIG. 3 (B), the adhesive layer 28 of the carrier sheet 26 is pressed against the surface of the internal electrode layer film 12a, heated and pressurized, and then the carrier sheet 26 is peeled off, whereby FIG. ), The adhesive layer 28 is transferred to the surface of the internal electrode layer film 12a.

  The heating temperature at that time is preferably 40 to 100 ° C., and the pressure is preferably 0.2 to 15 MPa. The pressurization may be a pressurization or a calender roll, but is preferably performed by a pair of rolls.

  Thereafter, the internal electrode layer film 12a is adhered to the surface of the green sheet 10a formed on the surface of the carrier sheet 30 shown in FIG. For this purpose, as shown in FIG. 4B, the internal electrode layer film 12a of the carrier sheet 20 is pressed together with the carrier sheet 20 through the adhesive layer 28 together with the carrier sheet 20, and heated and pressurized. As shown in FIG. 4C, the internal electrode layer film 12a is transferred to the surface of the green sheet 10a. However, since the carrier sheet 30 on the green sheet side is peeled off, when viewed from the green sheet 10 a side, the green sheet 10 a is transferred to the internal electrode layer film 12 a via the adhesive layer 28.

  The heating and pressurization at the time of transfer may be pressurization / heating with a press or pressurization / heating with a calender roll, but is preferably performed with a pair of rolls. The heating temperature and pressure are the same as when the adhesive layer 28 is transferred.

  3A to 4C, the internal electrode layer film 12a having a predetermined pattern is formed in a three-layer structure on the single green sheet 10a. By using this, a laminated body in which a large number of internal electrode layer films 12a and green sheets 10a are alternately laminated is obtained.

  Thereafter, the final pressure is applied to the laminate, and then the carrier sheet 20 is peeled off. The pressure at the time of final pressurization is preferably 10 to 200 MPa. Moreover, 40-100 degreeC is preferable for heating temperature.

  Thereafter, the laminate is cut into a predetermined size to form a green chip. Then, the green chip is subjected to binder removal processing and firing.

When Ni as a base metal is used for the main conductive layer of the internal electrode layer as in the present invention, the binder removal treatment is preferably performed in Air or N ₂ in a binder removal atmosphere. As other binder removal conditions, the temperature rising rate is preferably 5 to 300 ° C./hour, more preferably 10 to 50 ° C./hour, and the holding temperature is preferably 200 to 400 ° C., more preferably 250 to 350. The temperature holding time is preferably 0.5 to 20 hours, more preferably 1 to 10 hours.

In the present invention, the green chip is fired in an atmosphere with an oxygen partial pressure of preferably 10 ⁻¹⁴ to 10 ⁻⁶ Pa, more preferably 10 ⁻¹² to 10 ⁻⁸ Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode layer may abnormally sinter and break, and conversely if the oxygen partial pressure is too high, the internal electrode layer tends to oxidize. .

  In the present invention, the green chip is fired at a low temperature of preferably 900 ° C. or higher and lower than 1000 ° C. When the firing temperature is less than 900 ° C., densification of the dielectric layer after sintering tends to be insufficient and the capacitance tends to be insufficient, and when it is 1000 ° C. or more, the dielectric layer becomes over-fired, There is a tendency that the capacity change with time when a DC electric field is applied becomes large.

As other firing conditions, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the temperature holding time is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. The time and cooling rate are preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour. The firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ is preferably used in a wet (humidified) state.

  In the present invention, it is preferable to anneal the sintered capacitor chip body. Annealing is a process for re-oxidizing the dielectric layer, whereby the accelerated lifetime of the insulation resistance (IR) can be remarkably increased, and the reliability is improved.

In the present invention, it is preferable to anneal the capacitor chip body after firing under an oxygen partial pressure higher than the reducing atmosphere during firing. Specifically, the oxygen partial pressure is preferably 10 ^{−3 to} 100 Pa, more preferably It is performed in an atmosphere of 10 ^{−2 to} 10 Pa. If the oxygen partial pressure during annealing is too low, it is difficult to re-oxidize the dielectric layer 2, and conversely if too high, nickel in the internal electrode layer tends to oxidize and insulate.

  In the present invention, the holding temperature or maximum temperature during annealing is preferably 950 ° C. or lower, more preferably 750 to 950 ° C., and particularly preferably 800 to 950 ° C. In the present invention, the holding time of these temperatures is preferably 0.5 to 4 hours, more preferably 1 to 3 hours. If the holding temperature or maximum temperature during annealing is less than the above range, the dielectric material is insufficiently oxidized and the insulation resistance life tends to be shortened. In addition to a decrease, it tends to react with the dielectric substrate and shorten its lifetime. Note that annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature is synonymous with the maximum temperature.

As other annealing conditions, the cooling rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. Further, as the annealing atmosphere gas, for example, humidified N ₂ gas or the like is preferably used.

Note that to wet the N ₂ gas may be used, for example, a wetter or the like. In this case, the water temperature is preferably about 0 to 75 ° C.

The binder removal treatment, firing and annealing may be performed continuously or independently. When these are performed continuously, after removing the binder, the atmosphere is changed without cooling, and then the temperature is raised to the holding temperature at the time of baking to perform baking, and then cooled to reach the annealing holding temperature. Sometimes it is preferable to perform annealing by changing the atmosphere. On the other hand, when performing these independently, at the time of firing, after raising the temperature under N ₂ gas atmosphere with N ₂ gas or wet to the holding temperature of the binder removal processing, further continuing the heating to change the atmosphere Preferably, after cooling to the holding temperature at the time of annealing, it is preferable to change to the N ₂ gas or humidified N ₂ gas atmosphere again and continue cooling. In annealing, the temperature may be changed to a holding temperature in an N ₂ gas atmosphere, and then the atmosphere may be changed, or the entire annealing process may be a humidified N ₂ gas atmosphere.

The sintered body (element body 4) thus obtained is subjected to end surface polishing by, for example, barrel polishing, sand plast, etc., and terminal electrode paste 6 is baked to form terminal electrodes 6 and 8. The firing conditions for the terminal electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N ₂ and H ₂ . Then, if necessary, a pad layer is formed on the terminal electrodes 6 and 8 by plating or the like. In addition, what is necessary is just to prepare the paste for terminal electrodes like the above-mentioned electrode paste.
The multilayer ceramic capacitor of the present invention thus manufactured is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

  In the present embodiment, it is possible to provide the multilayer ceramic capacitor 2 in which the decrease in capacitance is effectively suppressed. Ru, Rh, Re, Pt, Ir and Os are noble metals having a melting point higher than that of Ni. Further, the sub-conductive layer 42 mainly composed of these metals or alloys is excellent in wettability and adhesion with the dielectric layer 10. Therefore, by forming the sub-conductive layer 42 between the main conductive layer 40 and the dielectric layer 10, the grain growth of Ni particles in the firing stage is suppressed, and spheroidization and electrode breakage are effectively prevented. And the fall of an electrostatic capacitance can be controlled effectively. Further, delamination between the internal electrode layer 12 and the dielectric layer 10 can be prevented. Furthermore, there is no firing failure of the dielectric powder.

  In the present embodiment, the dry-type internal electrode layer film 12a can be easily and highly accurately transferred to the surface of the green sheet 10a without breaking or deforming the green sheet 10a. . In particular, the adhesive layer 28 is formed on the surface of the electrode layer or the green sheet by a transfer method, and the internal electrode layer film 12a is adhered to the surface of the green sheet 10a via the adhesive layer 28. By forming the adhesive layer 28, when the internal electrode layer film 12a is transferred to the surface of the green sheet 10a and transferred, high pressure and heat are not required, and bonding at a lower pressure and a lower temperature is possible. Therefore, even when the green sheet 10a is very thin, the green sheet 10a is not destroyed, the internal electrode layer film 12a and the green sheet 10a can be satisfactorily laminated, and no short circuit failure occurs.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  For example, the present invention is not limited to a multilayer ceramic capacitor and can be applied to other electronic components.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples.

Example 1
Preparation of each paste First, BaTiO ₃ powder (BT-005 / Sakai Chemical Industry Co., Ltd.), MgCO ₃ , MnCO ₃ , Li ₂ SiO ₃ , SrO—B ₂ O ₃ —SiO ₂ —ZnO—Al ₂ O ₃ And rare earths (Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Y ₂ O ₃ ) The powder thus obtained was wet mixed by a ball mill for 16 hours and dried to obtain a dielectric material. These raw material powders had an average particle size of 0.1 to 1 μm. SrO—B ₂ O ₃ —SiO ₂ —ZnO—Al ₂ O ₃ is obtained by wet-mixing SrO, B ₂ O ₃ , SiO ₂ , ZnO and Al ₂ O ₃ with a ball mill, followed by baking in air after drying. It was prepared by wet pulverization with a ball mill.

  In order to make the obtained dielectric material into a paste, an organic vehicle was added to the dielectric material and mixed with a ball mill to obtain a dielectric green sheet paste. The organic vehicle is based on 100 parts by mass of the dielectric material, polyvinyl butyral: 6 parts by mass as a binder, bis (2-ethylhexyl) phthalate (DOP): 3 parts by mass, ethyl acetate: 55 parts by mass, toluene: The blending ratio is 10 parts by mass and 0.5 parts by mass of paraffin as a release agent.

  Next, a paste obtained by diluting the dielectric green sheet paste with ethanol / toluene (55/10) twice by weight was used as a release layer paste.

  Next, an adhesive layer paste was prepared by diluting the same dielectric green sheet paste described above with toluene in a weight ratio of 4 with the exception that the dielectric particles and the release agent were not added.

Formation of Green Sheet First, using the above dielectric green sheet paste, a green sheet having a thickness of 1.0 μm was formed on a PET film (second support sheet) using a wire bar coater.

Formation of Internal Electrode Layer Film The release layer paste was applied and dried on another PET film (first support sheet) with a wire bar coater to form a release layer having a thickness of 0.3 μm.

  Next, a mask on which a predetermined pattern serving as an internal electrode is formed is set on the surface of the release layer, and films 42a, 40a, and 42a are sequentially formed by sputtering as shown in FIG. A layer laminated film was formed.

  The first layer film 42a is a 0.05 μm thick Pt film (approximately 100% Pt), and the second layer film 40a is a 0.3 μm Ni film (approximately 100% Ni). The third layer film 42a was a Pt film (approximately 100% Pt) having a thickness of 0.05 μm.

As sputtering conditions, ultimate vacuum: 10 ⁻³ Pa or less, Ar gas introduction pressure: 0.5 Pa, output: 200 W, temperature: room temperature (20 ° C.).

Formation of Adhesive Layer The above-mentioned adhesive layer paste was applied and dried with a wire bar coater on another PET film (third support sheet) whose surface was subjected to a release treatment with a silicone-based resin. A 2 μm adhesive layer 28 was formed.

Formation of final laminate (element body before firing) First, the adhesive layer 28 was transferred to the surface of the internal electrode layer film 12a by the method shown in FIG. At the time of transfer, a pair of rolls were used, the pressure was 0.1 MPa, and the temperature was 80 ° C.

  Next, the internal electrode layer film 12a was adhered (transferred) to the surface of the green sheet 10a through the adhesive layer 28 by the method shown in FIG. At the time of transfer, a pair of rolls were used, the pressure was 0.1 MPa, and the temperature was 80 ° C.

  Next, the internal electrode layer film 12a and the green sheet 10a were laminated one after another, and finally, a final laminated body in which 21 internal electrode layer films 12a were laminated was obtained. The lamination conditions were a pressure of 50 MPa and a temperature of 120 ° C.

Production of sintered body Next, the final laminate was cut into a predetermined size and subjected to binder removal processing, firing and annealing (heat treatment) to produce a chip-shaped sintered body.

Binder removal
Temperature increase rate: 5 to 300 ° C./hour, particularly 10 to 50 ° C./hour,
Holding temperature: 200-400 ° C, especially 250-350 ° C,
Retention time: 0.5 to 20 hours, especially 1 to 10 hours,
Atmosphere gas: humidified mixed gas of N ₂ and H ₂ ,
I went there.

Firing is
Temperature increase rate: 5 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
Holding temperature: 950 ° C.
Retention time: 0.5-8 hours, especially 1-3 hours,
Cooling rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
Atmosphere gas: humidified mixed gas of N ₂ and H ₂ ,
Oxygen partial pressure: 10 ⁻¹¹ Pa,
I went there.

Annealing (reoxidation)
Temperature increase rate: 200 to 300 ° C./hour,
Holding temperature: 850 ° C.
Retention time: 2 hours
Cooling rate: 300 ° C./hour,
Atmospheric gas: humidified N ₂ gas,
Oxygen partial pressure: 10 ⁻² Pa,
I went there. The atmosphere gas was humidified using a wetter at a water temperature of 0 to 75 ° C.

Next, after polishing the end face of the chip-shaped sintered body with sand blasting, the external electrode paste is transferred to the end face and baked at 800 ° C. for 10 minutes in a humidified N ₂ + H ₂ atmosphere. A multilayer ceramic capacitor sample having the structure shown in FIG. 1 was obtained.

  The size of each sample thus obtained is 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between internal electrode layers is 21, and the thickness is 1 μm. The total thickness of the internal electrode layers was 0.4 μm, the thickness of the main conductive layer 40 was 0.3 μm, and the thickness of the sub conductive layer 42 was 0.05 μm. The thickness (film thickness) of each layer was measured by observing with SEM. As a result of observation by SEM, as shown in FIG. 2, it was confirmed that the main conductive layer 40 and the sub conductive layer 42 have a three-layer structure.

  Each sample was evaluated for electrical characteristics (capacitance C, resistivity, dielectric loss tan δ). The results are shown in each table. The electrical characteristics (capacitance C, resistivity, dielectric loss tan δ) were evaluated as follows.

  Capacitance C (unit: μF) was measured for a sample at a reference temperature of 25 ° C. using a digital LCR meter (4274A manufactured by YHP) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. The capacitance C is preferably 0.9 μF or more.

Resistivity (unit: Ω · m) was measured by using a resistivity meter (Σ-5, manufactured by NPS), a sputtered film (before firing) formed on a glass substrate at 25 ° C. by DC 4 probe method. Measurement was performed at a current of 1 mA for 2 seconds. The resistivity is preferably 70 × 10 ⁻⁸ Ω · m or less.

  The dielectric loss tan δ was measured at 25 ° C. with a digital LCR meter (4274A manufactured by YHP) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. The dielectric loss tan δ is preferably less than 0.1.

  In addition, these characteristic values were calculated | required from the average value of the value measured using the sample number n = 10 piece. These results are shown in Table 1. In Table 1, ○ in the column of evaluation criteria indicates that a good result was obtained in all the above characteristics, and × indicates that one of them did not give a good result. Show.

Comparative Example 1
Without forming the film 42a shown in FIG. 3, the film 40a made of a nickel film is formed with a thickness of 0.4 .mu.m, and only the main conductive layer 40 made of a single 0.4 .mu.m nickel film is formed as a dielectric layer. A capacitor sample was prepared in the same manner as in Example 1 except that it was formed between 10 and the same measurement as in Example 1 was performed. The results are shown in Table 1.

Example 2
The pair of films 42a constituting the sub-conductive layer 42 is made of ruthenium (Ru), rhodium (Rh), rhenium (Re), iridium (Ir) and osmium (Os) metal films (purity of about 100%). A capacitor sample was prepared in the same manner as in Example 1 except that it was configured in the same manner as in Example 1, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

Example 3
A capacitor sample was produced in the same manner as in Example 1 except that the sub conductive layer 42 was formed only on one side of the main conductive layer 40, and the same measurement as in Example 1 was performed. The results are shown in Table 1.

As shown in Evaluation Table 1, the effectiveness of the present invention was confirmed.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of the internal electrode layer shown in FIG. FIG. 3A to FIG. 3C are cross-sectional views of relevant parts showing a transfer method of the internal electrode layer film. 4 (A) to 4 (C) are cross-sectional views of relevant parts showing a step subsequent to FIG.

Explanation of symbols

2 ... Multilayer ceramic capacitor 4 ... Capacitor body 6, 8 ... Terminal electrode 10 ... Dielectric layer 10a ... Green sheet 12 ... Internal electrode layer 12a ... Internal electrode layer film (alloy film or conductive paste film)
20 ... Carrier sheet (first support sheet)
22 ... Release layer 26 ... Carrier sheet (third support sheet)
28 ... Adhesive layer 30 ... Carrier sheet (second support sheet)
40 ... Main conductive layer 42 ... Sub conductive layer

Claims (15)

An electronic component having an internal electrode layer and a dielectric layer,
The internal electrode layer is
A main conductive layer mainly composed of nickel;
A sub-conductive layer formed between the main conductive layer and the dielectric layer;
The electronic component, wherein the sub-conductive layer is a metal layer or an alloy layer having at least one element selected from rhenium (Re) and platinum (Pt) .   The electronic component according to claim 1, wherein the main conductive layer is sandwiched between a pair of sub conductive layers, and the internal electrode layer has a laminated structure of three or more layers.   3. An alloy layer of a main component metal constituting the main conductive layer and a main component metal constituting the sub conductive layer is formed between the main conductive layer and the sub conductive layer. Electronic components described in   The electronic component according to claim 1, wherein the dielectric layer is made of a dielectric material that can be fired in a reducing atmosphere.   The electronic component according to claim 1, wherein a thickness of the sub conductive layer is greater than 0 μm and equal to or less than 0.1 μm.   The electronic component according to claim 5, wherein the main conductive layer has a thickness of 0.1 to 1.0 μm. A multilayer ceramic capacitor having an element body in which internal electrode layers and dielectric layers are alternately laminated,
The internal electrode layer is
A main conductive layer mainly composed of nickel;
A sub-conductive layer formed between the main conductive layer and the dielectric layer;
The multilayer ceramic capacitor, wherein the sub-conductive layer is a metal layer or an alloy layer having at least one element selected from rhenium (Re) and platinum (Pt) . A method of manufacturing an electronic component having an internal electrode layer and a dielectric layer,
Forming a sub-conductive layer composed of a metal layer or alloy layer having at least one element selected from rhenium (Re) and platinum (Pt) ;
Laminating the sub-conductive layer to form a main conductive layer mainly composed of nickel;
Laminating the internal electrode layer having the sub conductive layer and the main conductive layer with a green sheet to be a dielectric layer after firing;
The manufacturing method of an electronic component which has the process of baking the laminated body of the said green sheet and the said internal electrode layer.   9. The electron according to claim 8, wherein the internal electrode layer is laminated on the green sheet so that the sub conductive layer is located between the main conductive layer and the green sheet in the internal electrode layer. A manufacturing method for parts.   10. The method of manufacturing an electronic component according to claim 8, wherein an adhesive layer is interposed between the internal electrode layer and the green sheet.   The said internal electrode layer is a manufacturing method of the electronic component in any one of Claims 8-10 which are formed on a support sheet | seat, and are peeled from the said support sheet | seat and laminated | stacked with respect to the said green sheet | seat after that.   The method of manufacturing an electronic component according to claim 8, wherein the sub conductive layer is formed by a thin film forming method, and the main conductive layer is formed by a printing method or a thin film forming method. . The manufacturing of the electronic component according to any one of claims 8 to 12, wherein the laminate is fired at a temperature of 900 ° C or higher and lower than 1000 ° C in an atmosphere having an oxygen partial pressure of 10 ^-14 to 10 ^-6 Pa. Method. The method for manufacturing an electronic component according to any one of claims 8 to 13, wherein after the laminate is fired, annealing is performed at a temperature of 950 ° C or lower in an atmosphere having an oxygen partial pressure of 10 ^{-3 to} 100 Pa. A method of manufacturing a multilayer ceramic capacitor having an element body in which internal electrode layers and dielectric layers are alternately stacked,
Forming a sub-conductive layer composed of a metal layer or alloy layer having at least one element selected from rhenium (Re) and platinum (Pt) as a main component;
Laminating the sub-conductive layer to form a main conductive layer mainly composed of nickel;
Laminating the internal electrode layer having the sub conductive layer and the main conductive layer alternately with a green sheet that becomes a dielectric layer after firing;
A method for producing a multilayer ceramic capacitor, comprising: firing a laminate of the green sheet and the internal electrode layer.

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