JP2005101547A - Manufacturing method of electronic component and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electronic component by which a ultrathin layer of a dielectric layer in electronic components such as, for example, a laminated ceramic capacitor is attained with less short fraction defective, and the electronic component obtained by the manufacturing method. <P>SOLUTION: The manufacturing method is to manufacture the electronic component including at least a pair of internal electrode layers 14, 16 and the dielectric layer 10 formed between the internal electrode layers. Electrode films 12a, 14a which are to form the internal electrode layers after burning are formed, including a conductive composition and a dielectric composition. The electrode films 12a, 14a are laminated with a buffer layer 40 in between which does not include a main dielectric component of the dielectric composition. The electrode films 12a, 14a laminated with the buffer layer 40 in between are burned, then the dielectric composition included in the electrode films 12a, 14a is diffused between the electrode films 12a, 14a to form the dielectric layer 10 between the electrode films 12a, 14a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electronic component manufacturing method and an electronic component, and more specifically, an electronic component manufacturing method capable of realizing ultrathin dielectric layer in a multilayer electronic component such as a multilayer ceramic capacitor, and the like. The present invention relates to an electronic component obtained by the manufacturing method.

  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. A pair of external terminal electrodes are formed on both ends of the substrate.

  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, for example, 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, the sintering temperature of the dielectric powder is lowered to 900 to 1100 ° C., an Ag—Pd alloy is used as the conductive material included in the internal electrode layer before firing, or reduction resistance is imparted to the dielectric material in a reducing atmosphere. The thing using cheap base metals, such as Ni which can be baked, is developed.

  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 capacity of the multilayer ceramic capacitor, it is required to further reduce the thickness of the dielectric layer green sheet.

  However, the reduction in the thickness of the green sheet is likely to cause a decrease in sheet strength and defects such as pinholes, resulting in an increase in short-circuit withstand voltage failure and various difficulties.

  Further, when Ni is used as 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.

  In addition, as shown in the following Patent Documents 1 to 3, in order to improve the adhesion between the internal electrode layer and the dielectric layer, and to reduce the difference in thermal shrinkage between these layers, In addition, techniques for including dielectric particles are known.

  However, in any of the methods described in Patent Documents 1 to 3, the dielectric layer is formed by firing a green sheet, which is insufficient in terms of thinning the dielectric layer.

  In order to solve such a problem, the present applicant has previously proposed an invention relating to the following patent application. In the present invention, an extremely thin dielectric layer is deposited by laminating electrode films without interposing a green sheet between the electrode films and depositing a dielectric composition contained in these electrode films. Yes.

However, in the invention proposed previously, although a very thin dielectric layer can be realized, a problem remains in terms of the short-circuit defect rate.
JP-A-10-172855 JP-A-11-124602 JP-A-11-354374 Japanese Patent Application No. 2003-171779.

  The present invention has been made in view of such a situation, for example, it is possible to realize an ultra-thin dielectric layer in an electronic component such as a multilayer ceramic capacitor, and a method for manufacturing an electronic component with a low short-circuit defect rate, and An object is to provide an electronic component obtained by the manufacturing method.

In order to achieve the above object, a method for manufacturing an electronic component according to the present invention includes:
A method of manufacturing an electronic component having at least a pair of internal electrode layers and a dielectric layer formed between the internal electrode layers,
Forming an electrode film comprising a conductive composition and a dielectric composition, and forming the internal electrode layer after firing;
Laminating the electrode film through a buffer layer substantially free of a dielectric main component of the dielectric composition;
The laminate of the electrode films laminated via the buffer layer is fired, the dielectric composition contained in the electrode film is diffused between the electrode films, and the dielectric layer is interposed between the electrode films. Forming the step.

  The buffer layer has a thickness of preferably 0.8 μm or less, more preferably 0.6 μm or less. The lower limit of the thickness of the buffer layer is preferably 0.01 μm, particularly preferably 0.05 μm.

  The buffer layer of the present invention is a layer that does not substantially contain a dielectric main component of the dielectric composition, and does not function as a dielectric layer by itself, unlike a conventional green sheet. By inserting this buffer layer between the electrode films, the diffusion of the dielectric composition between the electrode films is promoted, the deposition of an extremely thin dielectric layer is realized, and the diffusion of nickel is suppressed dramatically. Short circuit failure can be improved.

  The buffer layer may be a layer that does not substantially contain the dielectric composition, and may contain, for example, a synthetic resin component. For example, the buffer layer is made of a material that is vaporized and scattered from the laminate after firing.

  Generally, the sintering start temperature of nickel varies depending on the particle diameter, but since nickel powder having an average particle diameter of 0.1 to 0.4 μm is about 200 ° C. to 600 ° C., the buffer layer is preferably at least It is preferable to use a material that vaporizes at 200 ° C. or higher. Particularly preferably, the buffer layer is made of a material that hardly evaporates below 200 ° C. and vaporizes at 200 ° C. or higher.

  Alternatively, the buffer layer may be made of a material that remains after being baked into the dielectric layer deposited between the electrode films in the laminate. In that case, for the same reason as described above, the buffer layer is preferably made of a material that starts sintering at a temperature of 200 ° C. or higher.

Examples of the material of such a buffer layer include carbides, borates, lithium compounds, and the like. Alternatively, the buffer layer is a rare earth _{oxides, MgO, CaO, SrO, BaO} , SiO 2, V 2 O 5, MoO 3, WO 3, etc. as in MnO and _Cr 2 _{O 3,} the additive in the dielectric layer Subcomponent additives contained as: However, the buffer layer of the present invention does not substantially contain the dielectric main component of the dielectric composition.

  The composition of the buffer layer can be appropriately changed depending on the target thickness. In addition, it is important that the buffer layer is formed between the electrode films at the time of lamination. The buffer layer may be formed on a support sheet such as a PET film, and an electrode film may be formed thereon, or on the support sheet. The electrode film may be formed on the electrode film after the electrode film is formed. Alternatively, the electrode film and the buffer layer may be separately formed on separate support sheets, and each may be formed by a transfer method.

  That is, a buffer layer may be formed on the electrode film, or an electrode film may be formed on the buffer layer, and may be laminated by a transfer method using the buffer film as one block, or the electrode film and the buffer layer May be once formed on the surface of the support sheet, and then the electrode film and the buffer layer formed on the surface of each support sheet may be repeatedly laminated by a transfer method. Although the buffer layer and the electrode film can be formed on the electrode film by a printing method, it is difficult to obtain a layered structure of the buffer layer and the electrode film, and thus it is preferably formed by a transfer method.

  An adhesive layer may be formed on the surface of the electrode film formed on the surface of the support sheet. When the electrode film is thinned, it is preferable to laminate the electrode film by a transfer method. However, since the adhesion tends to be lowered, it is preferable to form an adhesive layer on the surface of the electrode film. The adhesive layer in the present invention is interposed between the electrode films, but assists the deposition of the dielectric composition between the electrode films when firing the laminated electrode films. There is also an effect.

  According to the method for manufacturing an electronic component according to the present invention, the dielectric composition contained in the electrode film can be obtained by merely firing the electrode film laminated through the buffer layer without laminating the green sheets between the electrode films. An object can be diffused between the electrode films to form a dielectric layer between the electrode films. The thickness of the dielectric layer obtained by the method of the present invention is, for example, an ultrathin layer of 1 μm or less, preferably 0.05 to 1.0 μm, and more preferably 0.05 to 0.8 μm.

  Moreover, in the present invention, since the dielectric composition contained in the electrode film is diffused between the electrode films using the buffer layer as an intermediary to form the dielectric layer between the electrode films, the dielectric layer having a uniform film thickness is formed. It is easy to form and it is possible to reduce short-circuit defects.

  Preferably, an internal electrode paste containing the conductive composition and the dielectric composition is prepared, and the electrode film is formed using the internal electrode paste. The electrode film may be formed by a thin film method, but by forming the electrode film by a printing method, it is easy to include a dielectric composition in addition to the conductive composition in the electrode film.

  In the present invention, the conductive composition is not particularly limited, but preferably, the conductive composition is composed of conductive particles mainly composed of a base metal such as nickel. By using an inexpensive base metal such as Ni, it contributes to lowering the price of electronic components.

In the present invention, the dielectric composition is not particularly limited. For example, dielectric main components such as calcium titanate, strontium titanate and / or barium titanate are used, and rare earth oxides, MgO, CaO, SrO, BaO are used. Subcomponent additives such as SiO ₂ , V ₂ O ₅ , MoO ₃ , WO ₃ , MnO and Cr ₂ O ₃ may be contained.

  Preferably, the dielectric composition is contained in the electrode film in a ratio of 10 to 80 parts by mass, more preferably 10 to 70 parts by mass with respect to 100 parts by mass of the conductive composition. When the addition amount of the dielectric composition is too small, the effect of the present invention tends to be reduced, and when the addition amount is too large, the conductivity of the internal electrode layer tends to be lowered.

  In general, if the amount of the dielectric composition added is too small, it is difficult to obtain the effect of suppressing the sintering of nickel, and the electrode tends to be easily cut off. Moreover, when there is too much addition amount, there exists a tendency for the electroconductivity of an internal electrode to fall from the fall of the dispersibility of nickel and an additive. For this reason, the preferred amount of addition of the dielectric ceramic composition has been limited to some extent.

  However, in the present invention, the main role of the addition of the dielectric composition is to form the dielectric layer by diffusing between the electrodes, so the role of the additive also has another meaning. . Of course, the addition of the dielectric ceramic composition also has the effect of suppressing the sintering of the electrode.

  A useful point of the present invention is that the thickness of the dielectric layer can be designed by the amount of the dielectric ceramic composition added. Therefore, the addition amount can be changed as appropriate. In the present invention, by changing the firing temperature, atmosphere, and firing method, the dielectric composition is efficiently diffused between the electrodes while suppressing breakage of the electrodes. Finally, the electrodes and the dielectric layers It is possible to obtain chip capacitors in which are alternately arranged.

  Since the firing atmosphere varies depending on the electrode material, it is not particularly limited in the present invention. However, when Ni is used, it is preferable to fire the laminated electrode film in a reducing atmosphere. When nickel particles are used as the conductive composition, if the particles are baked in an oxygen atmosphere, nickel is oxidized and the conductivity as an electrode tends to be lowered.

  The electronic component according to the present invention is obtained by any one of the electronic component manufacturing methods described above. In the present invention, the electronic component is not particularly limited, and examples thereof include multilayer ceramic capacitors, chip varistors, high-frequency multilayer components, multilayer components such as actuators, and the like.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention, FIGS. It is a cross-sectional photograph of the multilayer ceramic capacitor obtained by the method which concerns on one Example of invention.

  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 14, and the internal electrode layers 12 and 14 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 formed at one end of the capacitor body 4. The other internal electrode layers 14 stacked alternately are electrically connected to the inside of the second terminal electrode 8 formed at the other end of the capacitor element body 4.

  In addition, as a metal as a subcomponent which can comprise an alloy with nickel in each internal electrode layer 12 and 14, for example, Pt, Ru, Rh, Re, W, Ta, Ir, Os etc. are illustrated.

  The thickness of each internal electrode layer 12, 14 is preferably 0.05 to 1.2 μm, more preferably 0.05 to 1.0 μm. The internal electrode layers 12 and 14 are formed by transferring an electrode film, as will be described in detail later.

The material of the dielectric layer 10 is not particularly limited. For example, a dielectric main component made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate, a rare earth oxide, MgO, CaO, SrO, _BaO, composed of the _{SiO 2, V 2 O 5,} MoO 3, WO 3, subcomponent additives such as MnO and _Cr 2 _{O 3.} 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 in the present embodiment, for example, an ultrathin layer of 1 μm or less, preferably 0.05 to 1.0 μm, more preferably 0.05 to 0.8 μm. is there. Each dielectric layer 10 is formed by diffusion of a dielectric composition from the electrode film, as will be described later.

  A relatively thick dielectric outer layer 16 in which the internal electrode layers 12 and 14 are not formed is formed at both ends in the stacking direction of the dielectric layer 10 and the internal electrode layers 12 and 14. The dielectric outer layer 16 is formed by firing a conventionally known ceramic green sheet.

  Although the material of the terminal electrodes 6 and 8 is not specifically limited, Usually, copper, a copper alloy, nickel, a nickel alloy, etc. are used, However, Silver, the alloy of silver and palladium, etc. 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, as shown in FIG. 2, a relatively thick green sheet 16a is formed on a carrier sheet 30 made of a PET film as a support sheet. The green sheet 16a is a portion that becomes the dielectric outer layer 16 shown in FIG.

  The green sheet 16a is obtained by processing a dielectric paste into a sheet shape with a doctor blade or the like. 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 a dielectric material for the green sheet 16a, various compounds to be complex oxides and oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like can be selected as appropriate and used in combination. The dielectric material is usually used as a powder having an average particle size of about 0.1 to 1 μm.

  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, toluene, ethanol, propanol, and xylene 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, separately from the carrier sheet 30, as shown in FIG. 2, a carrier sheet 20 as a support sheet is prepared, and an electrode film 12a having a predetermined pattern is formed thereon, and the electrode film 12a is formed. A blank pattern film 24 is formed in a portion that has not been formed. The electrode film 12a is a portion that becomes the internal electrode layer 12 shown in FIG. 1 after firing. The blank pattern film 24 is formed after firing a dielectric portion corresponding to a gap between the terminal electrodes 6 and 8 not connected to the internal electrode layer 12 or 14 shown in FIG. 1 and the end of the internal electrode layer 12 or 14, respectively. . The support sheet 20 is made of, for example, a PET film.

  The electrode film 12a is first formed on the surface of the carrier sheet 20 by, for example, a printing method. Examples of the printing method include screen printing. When the electrode film 12a is formed on the surface of the carrier sheet 20 by a screen printing method which is a kind of printing method, for example, the following is performed.

  First, metal powder or alloy powder (conductive composition) contained in the film 12a is prepared. The average particle size of these powders is preferably 0.01 to 1 μm (more preferably 0.01 to 0.5 μm). Each metal powder or alloy powder is kneaded with an organic vehicle to form a paste, thereby obtaining a conductive paste (internal electrode paste) for forming the film 12a. The organic vehicle may use the same material as in the dielectric paste, but may be different.

  In the present embodiment, the conductive paste includes a dielectric composition (main component composition and / or ceramic sub-composition). The particle size of the dielectric material contained in the conductive paste is preferably 0.01 to 1.0 μm, more preferably 0.01 to 0.5 μm. Moreover, the dielectric material is preferably contained in a proportion of 10 to 80 parts by mass, more preferably 10 to 70 parts by mass with respect to 100 parts by mass of the conductive composition.

  The effect of the dielectric material added to the conductive paste is to suppress sintering of the metal powder of the conductive paste. However, in the embodiment of the present invention, this dielectric material diffuses as it is between the electrode layers to form a dielectric layer. Therefore, grain growth is controlled by the firing method, and after firing, a dielectric layer having a desired sintered body particle size can be formed. In the present invention, as described above, it is possible to easily design between layers, but it is also possible to control the grain size after sintering (control of dielectric constant). Therefore, the particle size of the dielectric material added to the conductor paste is not limited to this range in terms of designing dielectric characteristics, but can be changed as appropriate, not only as a role as a conductive paste.

  The blank pattern film 24 is made of the same material as that of the green sheet 16a and is formed by the same method. The thickness of the blank pattern film 24 is approximately the same as the thickness of the electrode film 12a. The electrode film 12a and the blank pattern film 24 are dried as necessary. The drying temperature is not particularly limited, but is preferably 70 to 120 ° C, and the drying time is preferably 5 to 15 minutes. The blank pattern film 24 may be provided as necessary.

  In the present embodiment, the buffer layer 40 is formed on the surfaces of the electrode film 12 a and the blank pattern film 24. Unlike the green sheet 16a and the blank pattern film 24, the buffer layer 40 does not contain a dielectric composition (a dielectric main component such as barium titanate).

  Since the buffer layer 40 of the present embodiment may also function as a transfer adhesive layer, it may contain a component having excellent adhesiveness. Specifically, the buffer layer 40 is composed of a synthetic resin component. As a synthetic resin component, it is comprised with the organic substance or emulsion which consists of an acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, a polyurethane, a polystyrene, or these copolymers, for example. The constituent resin component contained in the buffer layer may be the same as or different from the resin component contained in the green sheet 16a or the electrode film 12a.

  In the embodiment of the present invention, the structure in which the buffer layer 40 is interposed between the electrode films is effective in reducing remarkable short-circuit defects. The buffer layer 40 is preferably made of a material that is vaporized and scattered from the laminate after firing. This is because, when the component of the buffer layer is a specific component, it may affect the electrical characteristics when it finally diffuses into the dielectric layer.

  The substance that is vaporized and scattered may be a resin component, and preferably includes a carbide, a boric acid compound, or a lithium compound. However, the range is not limited.

  Alternatively, the buffer layer 40 may be made of a material that remains after being baked into the dielectric layer 10 deposited between the electrode films in the laminate. In that case, the buffer layer 40 is preferably made of a material that starts sintering at a temperature of 200 ° C. or higher.

  The thickness of the buffer layer 40 is preferably 0.8 μm or less, more preferably 0.6 μm or less. The lower limit of the thickness of the buffer layer 40 is preferably 0.01 μm, particularly preferably 0.05 μm. The particle size of the dielectric composition material contained in the buffer layer is preferably 0.01 to 0.5 μm. The method for forming the buffer layer is not particularly limited, and examples thereof include a coating method such as a wire bar coater, a die coater, and a doctor blade, or a thin film forming method such as sputtering.

  The electrode film 12a and the blank pattern film 24 formed on the surface of the carrier sheet 20 are transferred to the surface of the green sheet 16a through the buffer layer 40 as shown in FIG. The film 12a and the blank pattern film 24 are peeled off.

  Thereafter, as shown in FIG. 3, the electrode film 14 a and the blank pattern film 24 are formed on the surfaces of the electrode film 12 a and the blank pattern film 24 through the buffer layer 40 in the same manner as the electrode film 12 a and the blank pattern film 24. It is formed by a transfer method. The electrode film 14a is a portion that becomes the internal electrode layer 14 shown in FIG. 1, and is formed in the same manner as the electrode film 12a except that the pattern is different.

  By repeating such transfer on the green sheet 16a, a laminate in which the electrode films 12a and the electrode films 14a are alternately laminated via the buffer layer 40 can be 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.

  In the case of using Ni as a base metal for the internal electrode layer as in this embodiment, the binder removal treatment is preferably performed in the air or in a reducing atmosphere. As other binder removal conditions, the rate of temperature rise is preferably 5 to 300 ° C./hour, the holding temperature is preferably 200 to 400 ° C., and the temperature holding time is preferably 0.5 to 20 hours.

In the present embodiment, the green chip is fired in an atmosphere with an oxygen partial pressure of preferably 10 ⁻¹⁰ to 10 ⁻² 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 this embodiment, the green chip is fired at a low temperature of 1350 ° C. or lower. If the firing temperature is too low, the green chip will not be densified. Conversely, if the firing temperature is too high, the internal electrode may be interrupted, the capacitance-temperature characteristics may deteriorate due to diffusion of the conductive material, and the dielectric may be reduced. Because it ends up.

As other firing conditions, the heating rate is preferably 50 to 500 ° C./hour, the temperature holding time is preferably 0.5 to 8 hours, and the cooling rate is preferably 50 to 500 ° 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 embodiment, it is preferable to anneal the capacitor chip body after firing. 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 this embodiment, it is preferable to anneal the capacitor chip body after firing under an oxygen partial pressure higher than the reducing atmosphere at the time of firing. Specifically, the oxygen partial pressure is preferably 10 ^{−4 to} 100 Pa. Do. If the oxygen partial pressure during annealing is too low, it is difficult to reoxidize the dielectric layer. Conversely, if it is too high, nickel in the internal electrode layer tends to be oxidized and insulated.

  In the present embodiment, the holding temperature or maximum temperature during annealing is preferably 1200 ° C. or lower. In this embodiment, the holding time of these temperatures is preferably 0.5 to 4 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. 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 this embodiment manufactured in this way is mounted on a printed circuit board or the like by soldering or the like and used for various electronic devices.

  In this embodiment, without laminating green sheets between the electrode films 12a and 14a, the electrode films 12a and 14a stacked via the buffer layer 40 are merely fired, and are included in the electrode films 12a and 14a. The dielectric composition diffuses and deposits between the electrode films 12a and 14a during firing using the buffer layer 40 as an intermediary, and then sinters. As a result, as shown in FIG. 4, an ultrathin dielectric layer 10 of 1 μm or less, for example, can be formed between the internal electrode layers 12 and 14.

  Further, in the present embodiment, the electrode films 12a and 14a are not directly stacked, but are stacked via the buffer layer 40, so that short-circuit defects in the dielectric layer after firing can be reduced.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, the present invention is not limited to a multilayer ceramic capacitor and can be applied to other electronic components. In the embodiment shown in the above-described figure, the buffer layer 40 is formed on the surfaces of the electrode films 12a and 14a and the blank pattern film 24. However, the support sheet 20 and the electrode films 12a and 14a and the blank pattern film 24 A buffer layer 40 may be formed therebetween. In any case, these buffer layers 40 are interposed between the stacked electrode films 12a and 14a.

  Hereinafter, the present invention will be described based on more specific examples. However, the present invention is not limited to the following examples.

Dielectric paste for outer layer BaTiO ₃ powder (average particle size: 0.2 μm) 100 parts by weight MgCO ₃ 0.72 parts by weight MnO 0.13 parts by weight (Ba _0.6 Ca _0.4 ) SiO ₃ 1.5 parts by weight 1.0 part by weight of Y ₂ O ₃ .

  An organic vehicle having the following composition was added to 100 parts by weight of the dielectric powder thus prepared, and mixed for 20 hours using a ball mill to prepare a buffer layer paste.

Polyvinyl butyral resin (binder) 6 parts by weight DOP [bisphthalate (2-hexylhexyl)] (plasticizer) 3 parts by weight Ethanol 78 parts by weight n-propanol 78 parts by weight Xylene 14 parts by weight Mineral spirit 7 parts by weight Dispersant 0. 7 parts by weight.

Internal Electrode Paste The mixture ratio shown below was kneaded by a ball mill to form a slurry for internal electrode. That is, 30 parts by mass of ceramic powder (BaTiO ₃ powder and ceramic powder subcomponent additive) with respect to 100 parts by mass of Ni particles (electrode material powder) having an average particle size of 0.2 μm, polyvinyl butyral 4.4 parts by mass of resin and 95 parts by mass of terpineol were added, kneaded by a ball mill, and slurried to obtain an internal electrode paste.

As ceramic powder, with respect to 100 parts by mass of BaTiO ₃ powder (average particle size: 0.1 μm), (Ba _0.6 Ca _0.4 ) SiO ₃ : 1.5 parts by mass, Y ₂ O ₃ : A ceramic powder containing 1.0 part by mass, MgCO ₃ : 0.72 part by mass, and MnO: 0.13 part by mass was used.

Blank Pattern Film Paste A blank pattern film paste was prepared as follows.

  To the same ceramic powder (150 g) as the internal electrode paste, an ester polymer dispersant (1.5 g), terpineol (5 g), acetone (60 g), and dioctyl phthalate (5 g) as a plasticizer Was added and mixed for 4 hours. Next, 8% lacquer (8% polyvinyl butyral with respect to the total amount of lacquer) of BH6 (polymerization degree: 1450, degree of butyralization: 69 mol% ± 3% polyvinyl butyral resin) manufactured by Sekisui Chemical Co., Ltd. Mass% and terpineol 92 mass%) was added in an amount of 120 g and mixed for 16 hours. Then, the excess solvent acetone was removed, and 40-100 g of terpineol was added as a viscosity adjustment to prepare a blank pattern film paste.

Buffer layer paste

  An organic vehicle having the following composition was added to 100 parts by weight of 0.1 μm carbon black powder, and mixed for 20 hours using a ball mill to prepare a buffer layer paste.

Polyvinyl butyral resin (binder) 6 parts by weight DOP [bisphthalic acid (2-hexylhexyl)] (plasticizer) 3 parts by weight Ethanol 200 parts by weight n-propanol 200 parts by weight Xylene 36 parts by weight Mineral spirit 7 parts by weight Dispersant 0. 7 parts by weight.

The electrode film 12 a and the blank pattern film 24 were formed on the PET film as the film forming process support sheet 20. The electrode film 12a was formed with a thickness of 1 μm by the printing method using the above internal electrode paste. The blank pattern film 24 was formed with a thickness of 1 μm by a printing method using the blank pattern film paste.

  Next, the buffer layer paste was applied onto another support sheet with a wire bar coater to form a buffer layer 40 of about 0.6 μm. Further, an outer layer green sheet 16a was formed on another support sheet 30 by a doctor blade method using an exterior dielectric paste.

From the stacking process to the firing process buffer layer 40, the electrode film 12a and the blank pattern film 24 formed on the surface were used as one block, and these blocks were stacked on the exterior green sheet 16a by a transfer method. A normal green sheet serving as a dielectric layer was not laminated between the electrode layers in the laminated body before firing, and only the buffer layer was laminated. The laminated body was subjected to binder removal processing, firing and annealing (heat treatment) processing to produce a chip-shaped sintered body.

The binder removal was performed at a holding temperature of 260 ° C., a holding time of 8 hours, and an atmosphere gas: a humidified mixed gas of N ₂ and H ₂ .

Firing was performed at a heating rate of 200 ° C./hour, a holding temperature of 1240 ° C., a holding time of 2 hours, an atmosphere gas: a humidified mixed gas of N ₂ and H ₂ , and an oxygen partial pressure of 10 ⁻⁷ Pa.

Annealing (reoxidation) was performed at a holding temperature of 1050 ° C., a holding time of 2 hours, an atmosphere gas of humidified N ₂ gas, and an oxygen partial pressure of 10 ⁻¹ Pa. The atmosphere gas was humidified using a wetter at a water temperature of 0 to 75 ° C.

  Next, the end surface of the chip-shaped sintered body was polished by sandblasting, and a cross-sectional photograph was taken. The results are shown in FIG. As shown in FIG. 5, it was confirmed that a dielectric layer of about 0.38 μm (baked layer in Table 1) was deposited between about 1 μm of internal electrode layers made of Ni. It was also confirmed that the capacitance between the pair of internal electrode layers was about 49 nF. The results are shown in Table 1.

  The capacitance was measured with respect to a sintered sample at a reference temperature of 25 ° C. using a digital LCR meter (4272A manufactured by YHP) under conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. .

  Moreover, the short defect rate was measured. The short-circuit defect rate was 39%. The results are shown in Table 1. The short defect rate was measured by preparing 100 samples and examining the number of short defects.

実施例２〜５および比較例１および２
電極膜１２ａを形成するための内部電極用ペーストにおけるＮｉ粒子１００質量部に対して、セラミック粉体の質量部を、０〜９０質量部（表１では誘電体組成物量）の範囲で変化させた以外は、実施例１と同様にして、チップ形状の焼結体を作製し、同様な測定を行った。結果を表１に示す。 The short-circuit failure means that a pair of electrodes come into contact with each other with respect to a sintered body sample. Specifically, using an insulation resistance meter (E2377A multimeter manufactured by HEWLETT PACKARD), the insulation resistance value after applying DC 10 V for 60 seconds at 25 ° C. was measured, and 10Ω or less was regarded as a short circuit failure.

Examples 2-5 and Comparative Examples 1 and 2
The mass part of the ceramic powder was changed in the range of 0 to 90 parts by mass (the amount of the dielectric composition in Table 1) with respect to 100 parts by mass of the Ni particles in the internal electrode paste for forming the electrode film 12a. Except for the above, a chip-shaped sintered body was produced in the same manner as in Example 1, and the same measurement was performed. The results are shown in Table 1.

Evaluation 1
As shown in Table 1, the addition amount of the dielectric composition with respect to nickel of the internal electrode paste is 0 part by mass, that is, when there is no addition, even if there is a buffer layer, the buffer layer alone is insufficiently densified. Therefore, the electrostatic capacity could not be obtained.

  Moreover, when the addition amount of the dielectric composition is 90 parts by mass with respect to nickel of the internal electrode paste, the thickness of the dielectric layer becomes 1 μm or more, which is not suitable for the thin layer intended by the present invention. Further, the increase in the addition amount resulted in poor dispersion of nickel and the dielectric composition in the paste, the electrode was easily interrupted, and the capacity was reduced.

  Therefore, it was confirmed that the addition amount of the dielectric composition contained in the electrode film is preferably 10 to 80 parts by mass with respect to 100 parts by mass of the conductive composition such as nickel.

Comparative Example 3
A chip-shaped sintered body was produced in the same manner as in Example 1 except that the electrode films were laminated without interposing a buffer layer, and the thickness of the dielectric layer (baked layer), capacitance, In addition, the short-circuit defect rate was measured. The results are shown in Table 1.

Evaluation 2
As shown in Table 2, it was confirmed that in Comparative Example 3 without the buffer layer, the short-circuit defect rate was 92%, but in Example 1, it could be reduced to 39%.

Example 6
In the same manner as in Example 1 except that the same polyvinyl butyral resin as that used as the binder resin of the dielectric paste for the outer layer was added instead of the carbon powder in the buffer layer paste, the chip-shaped sintering was performed. The body was prepared, and the thickness of the dielectric layer (baked layer), the capacitance, and the short-circuit defect rate were measured. The results are shown in Table 1.

Example 7
It was confirmed that similar results were obtained even when B ₂ O ₃ as a borate or Li ₂ CO ₃ as a lithium compound was used instead of carbon black in Example 1.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the main part showing the manufacturing process of the multilayer ceramic capacitor shown in FIG. FIG. 3 is a cross-sectional view of relevant parts showing a step continued from FIG. FIG. 4 is a cross-sectional view of a principal part showing a step continued from FIG. FIG. 5 is a cross-sectional photograph of a multilayer ceramic capacitor obtained by the method according to one embodiment of the present invention.

Explanation of symbols

2 ... Multilayer ceramic capacitor 4 ... Capacitor body 6, 8 ... Terminal electrode 10 ... Dielectric layer 12, 14 ... Internal electrode layer 12a, 14a ... Electrode film 16 ... Dielectric outer layer 16a ... Green sheet 20, 30 ... Carrier sheet ( Support sheet)
24 ... Margin pattern film 40 ... Buffer layer

Claims (14)

A method of manufacturing an electronic component having at least a pair of internal electrode layers and a dielectric layer formed between the internal electrode layers,
Forming an electrode film comprising a conductive composition and a dielectric composition, and forming the internal electrode layer after firing;
Laminating the electrode film through a buffer layer substantially free of a dielectric main component of the dielectric composition;
The laminate of the electrode films laminated via the buffer layer is fired, the dielectric composition contained in the electrode film is diffused between the electrode films, and the dielectric layer is interposed between the electrode films. And a method of manufacturing an electronic component. The method of manufacturing an electronic component according to claim 1, wherein the buffer layer has a thickness of 0.8 μm or less. The method for manufacturing an electronic component according to claim 1, wherein the buffer layer is made of a material that is vaporized and scattered from the laminate after firing. The method for manufacturing an electronic component according to claim 3, wherein the buffer layer includes a synthetic resin component. The method for manufacturing an electronic component according to claim 3, wherein the buffer layer is made of a material that vaporizes at 200 ° C. or higher. The method for manufacturing an electronic component according to claim 1, wherein the buffer layer is made of any one of carbide, borate, and lithium compound. The electronic component according to claim 1, wherein the dielectric composition is included in the electrode film at a ratio of 10 to 80 parts by mass with respect to 100 parts by mass of the conductive composition. Manufacturing method. The method for manufacturing an electronic component according to claim 1, wherein the conductive composition is composed of conductive particles containing a base metal as a main component. The internal electrode paste containing the conductive composition and the dielectric composition is prepared, and the electrode film is formed using the internal electrode paste. The manufacturing method of the electronic component of description. The electrode film and the buffer layer are once formed on the surface of a support sheet, and then the electrode film and the buffer layer formed on the surface of the support sheet are laminated on another electrode film by a transfer method. The manufacturing method of the electronic component in any one of 1-9. The method of manufacturing an electronic component according to claim 10, wherein the buffer layer is formed on a surface of the electrode film. The method of manufacturing an electronic component according to claim 11, wherein the buffer layer is formed between the electrode film and a support sheet. The method of manufacturing an electronic component according to claim 1, wherein the laminated electrode film is fired in a reducing atmosphere. The electronic component obtained by the manufacturing method of the electronic component in any one of Claims 1-13.

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