JP2011151149A - Method for manufacturing laminated electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a laminated electronic component such as a laminated ceramic capacitor in which structural defects such as cracks caused in a polishing step are suppressed. <P>SOLUTION: The method for manufacturing a laminated electronic component having an element body in which a ceramic layer and an electrode layer are laminated includes a step of cutting a green laminate in which a green sheet and an electrode pattern are laminated to obtain a green chip including at least a binder resin, a solvent, and a plasticizer, a step of heat-treating the green chip in an atmosphere as a depressurized atmosphere having a pressure lower than an atmospheric pressure and in which the oxygen partial pressure in the atmosphere is ≥10 Pa and lower than the oxygen partial pressure in the air at the atmospheric pressure, a step of polishing the green chip subjected to the heat treatment, and a step of applying de-bindering and baking to the green chip after polishing to obtain an element body. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  With recent miniaturization of electronic devices, there has been a demand for miniaturization and large capacity of multilayer electronic components such as multilayer ceramic capacitors. In order to reduce the size and increase the capacity of a multilayer ceramic capacitor, the thickness of each dielectric layer is made as thin as possible (thinning), and the number of dielectric layers in a given size is increased as much as possible (multilayering) )It is necessary.

  However, as the dielectric layer becomes thinner and multilayered, structural defects (cracks and non-lamination) are likely to occur in the obtained capacitor. If a structural defect occurs inside the capacitor, it cannot be used as a capacitor, resulting in a defective product.

  As one of the causes of the structural defect, there is a large impact force at the time of polishing in the step of polishing the green chip obtained by cutting the green laminate.

  As a means for suppressing the occurrence of cracks, for example, in Patent Document 1, a pre-laminated laminate is dried, and then further laminated to form a final laminate, which is cut to obtain a green chip and solidified and dried It is carried out. And it is described that the occurrence of cracks is suppressed by setting the amount of solvent during solidification drying to a specific range.

  However, Patent Document 1 does not consider structural defects that occur due to the impact force during polishing.

JP 2007-294886 A

  Since the multilayer electronic component usually has a rectangular parallelepiped shape, a component defect (cracking or chipping) due to collision between components occurs in the manufacturing process. On the other hand, the above-mentioned defects are suppressed by polishing a green chip or a sintered body and rounding corners.

  In addition, since the green chip contains organic components such as a binder resin, a solvent, and a plasticizer, the green chip has a relatively low hardness and the chips are more likely to adhere to each other. Therefore, heat treatment is performed before polishing to remove organic components, thereby increasing the hardness of the green chip to prevent adhesion and improve polishing efficiency. At this time, if there are many remaining organic components, cracks may occur in the binder removal step or the like.

  Furthermore, the present inventors have found that in such a polishing process, not only a directly generated crack but also a fine structural defect (crack generation source) is introduced into the chip. This source of cracks does not occur as a crack in the manufacturing process, but when using or during the use of electronic parts made as products, solder stress during mounting, bending of the mounted substrate, internal stress of the product itself, etc. As a result, it was found that the crack generation source progresses (grows) and manifests itself as a crack or non-lamination.

  The object of the present invention is to suppress the occurrence of structural defects such as direct cracks caused by the manufacturing process (polishing process, debinder process, etc.), and when using electronic parts made as products. It is an object of the present invention to provide a method of manufacturing a multilayer electronic component such as a multilayer ceramic capacitor in which cracks induced by the crack are suppressed.

In order to achieve the above object, a manufacturing method of a multilayer electronic component according to the present invention includes
A method of manufacturing a multilayer electronic component having an element body in which a ceramic layer and an electrode layer are laminated,
Cutting a green laminate in which a green sheet and an electrode pattern are laminated to obtain a green chip containing at least a binder resin, a solvent, and a plasticizer;
Heat-treating the green chip in a reduced-pressure atmosphere having a pressure lower than atmospheric pressure and an oxygen partial pressure in the atmosphere being 10 Pa or higher and lower than an oxygen partial pressure in air at atmospheric pressure;
Polishing the green chip after heat treatment;
A step of removing the binder and baking the green chip after polishing to obtain the element body.

  In the present invention, the atmospheric pressure and the oxygen partial pressure are controlled within the above ranges. By doing in this way, organic components (solvent and plasticizer) other than binder resin can fully be removed, suppressing decomposition | disassembly of binder resin in a heat treatment process. As a result, the adhesion between the layers of the chip is ensured while maintaining the shape retention of the chip. Therefore, it is possible to effectively suppress crack generation sources (microcracks) inside the chip that cause direct cracks or cracks induced during use in the polishing process. In addition, variations in peel strength can be reduced in the element body after firing.

  Preferably, the atmospheric pressure in the reduced pressure atmosphere is 40 Pa or more and less than atmospheric pressure. By controlling the atmospheric pressure within the above range, the effect of the present invention can be further enhanced.

  Preferably, the amount of carbon remaining in the green chip is 3.5 to 5.0% by weight with respect to 100% by weight of the green chip after the heat treatment. The effect of the present invention can be further enhanced by controlling the residual carbon amount within the above range.

  Preferably, the green chip is polished by wet barrel polishing. By doing in this way, the effect of the present invention can be raised more.

Preferably, the method further includes a step of forming a terminal electrode on the surface of the element body,
The terminal electrode includes a baking layer formed by baking a terminal electrode coating applied to the surface of the element body, and a plating layer formed on the baking layer. By doing in this way, the effect of the present invention can be raised more.

  The multilayer electronic component manufactured according to the present invention is not particularly limited, but includes a multilayer ceramic capacitor, a piezoelectric element, a chip varistor, a chip thermistor, a chip inductor, a chip resistor, and other surface mount (SMD) chip electronic components. Illustrated.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor manufactured by a method for manufacturing a multilayer electronic component according to an embodiment of the present invention. FIG. 2A to FIG. 2B are cross-sectional views illustrating the main part of an example of a lamination process of a green sheet and an electrode pattern. FIG. 3A to FIG. 3B are cross-sectional views showing the main part of the process subsequent to FIG.

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

Overall Configuration of Multilayer Ceramic Capacitor First, the overall configuration of a multilayer ceramic capacitor will be described as an example of a multilayer electronic component manufactured by the method according to the present invention.

  As shown in FIG. 1, the multilayer ceramic capacitor 2 according to this 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 as ceramic layers 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 one end 4 a of the capacitor body 4. The other internal electrode layers 12 stacked alternately are electrically connected to the inside of the second terminal electrode 8 formed outside the other end 4 b of the capacitor body 4.

  The material of the dielectric layer 10 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate, barium titanate, or a mixture thereof. The thickness of each dielectric layer 10 is not particularly limited, but is generally several μm to several hundred μm. In the present embodiment, it is preferably 1.0 to 5.0 μm.

  Although the conductor material contained in the internal electrode layer 12 is not particularly limited, a relatively inexpensive base metal can be used when the constituent material of the dielectric layer 10 has reduction resistance. As the base metal, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 wt% or less. The internal electrode layer 12 may be formed using a commercially available electrode paste. What is necessary is just to determine the thickness of the internal electrode layer 12 suitably according to a use etc.

  The material of the terminal electrodes 6 and 8 is not particularly limited, and usually copper, a copper alloy, nickel, a nickel alloy, or the like is used, but silver, an alloy of silver and palladium, 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).

Method for Manufacturing Multilayer Ceramic Capacitor Next, a method for manufacturing the multilayer ceramic capacitor 2 will be described as an example of the manufacturing method according to the present embodiment.

  First, in order to form a green sheet that will constitute the dielectric layer 10 shown in FIG. 1 after firing, a green sheet paint is prepared.

  In this embodiment, the green sheet paint is composed of an organic solvent-based paste or a water-based paste obtained by kneading a dielectric material and an organic vehicle.

  As a raw material of the dielectric material, various compounds that become composite oxides and oxides as described above, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like can be appropriately selected and mixed for use. The raw material for the dielectric material is usually used as a powder having an average particle diameter of preferably 0.2 to 0.5 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 resin in an organic solvent. The binder resin used for the organic vehicle is not particularly limited, and examples thereof include various usual binder resins such as ethyl cellulose, polyvinyl butyral, and acrylic resin.

  Also, the organic solvent used in the organic vehicle is not particularly limited, and usual organic solvents such as alcohol, acetone, methyl ethyl ketone (MEK), toluene, xylene, ethyl acetate, butyl stearate, terpineol, butyl carbitol, isobornyl acetate, etc. Is exemplified.

  When the green sheet paint is an aqueous paste, a water-soluble material such as polyvinyl alcohol may be used as the binder resin.

  The green sheet paint may contain additives selected from various dispersants, plasticizers, antistatic agents, dielectrics, glass frit, insulators, and the like, if necessary. In order to improve the moldability and stackability of the green sheet, the plasticizer preferably contains a plasticizer. However, the total content of these is preferably 10 parts by weight or less.

  Examples of the plasticizer include phthalate esters such as dioctyl phthalate and benzylbutyl phthalate, adipic acid, phosphate esters, glycols, and the like. The weight ratio of the plasticizer in the paint in the case of blending the plasticizer is not particularly limited, and is preferably 40 to 70 parts by weight with respect to 100 parts by weight of the binder. 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.

Formation of Green Sheet Next, as shown in FIG. 2 (A), using the above-described green sheet coating material, the carrier sheet 20 as a support is preferably formed to a thickness of about 2.0 to 7.0 μm. The green sheet 10a is formed.

  As the carrier sheet 20, for example, a PET film or the like is used, and a film coated with silicone or the like is preferable in order to improve peelability.

  The green sheet 10 a is dried after being formed on the carrier sheet 20. The drying temperature of the green sheet 10a is preferably 50 to 100 ° C., and the drying time is preferably 1 to 5 minutes.

  Further, a green sheet 10a is further formed on the green sheet 10a, and an outer layer green sheet in which a plurality of green sheets 10a are stacked is prepared.

Formation of Electrode Pattern Next, as shown in FIG. 2B, an electrode pattern 12a that will form the internal electrode layer 12 shown in FIG. 1 after firing is formed on one surface of the green sheet 10a. . A method for forming the electrode pattern 12a is not particularly limited, and examples thereof include a printing method, a transfer method, and a thin film method. In the present embodiment, the internal electrode layer coating material is applied in a predetermined pattern on the green sheet 10a by screen printing. Thereafter, the electrode pattern 12a is formed by drying.

  The coating material for the internal electrode layer is prepared by kneading a conductive material made of various conductive metals and alloys, or various oxides, organometallic compounds, resinates, and the like that become the conductive material described above after firing with an organic vehicle. .

  In the present embodiment, it is preferable to use Ni, Ni alloy, or a mixture thereof as the conductor material used when manufacturing the internal electrode layer coating material. There are no particular restrictions on the shape of such a conductor material, such as a spherical shape or a flake shape, and a mixture of these shapes may be used.

  The organic vehicle contains a binder resin and an organic solvent, similar to that of the green sheet paint. Examples of the binder resin include ethyl cellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, and copolymers thereof. The binder resin is preferably included in the internal electrode layer coating material in an amount of 8 to 20 parts by weight with respect to 100 parts by weight of the conductor material (metal or alloy powder).

  As the solvent, any known solvent such as terpineol, butyl carbitol, or kerosene can be used. The content of the solvent is preferably about 20 to 55 parts by weight with respect to the entire paste.

  The internal electrode layer coating material may contain additives selected from various dispersants, plasticizers, antistatic agents, dielectrics, glass frit, insulators, and the like as required. However, the total content of these is preferably 10 parts by weight or less.

  In the present embodiment, since the plasticizer improves the moldability and stackability of the electrode pattern, the internal electrode layer paint preferably contains a plasticizer. Examples of the plasticizer include phthalic acid esters such as benzylbutyl phthalate (BBP), adipic acid, phosphoric acid esters, glycols, and the like. The content of the plasticizer is preferably 10 to 300 parts by weight, more preferably 10 to 200 parts by weight with respect to 100 parts by weight of the binder resin in the internal electrode layer coating material. In addition, when there is too much content of a plasticizer, it exists in the tendency for the intensity | strength of the electrode pattern 12a to fall remarkably.

  Note that the internal electrode layer coating material may contain ceramic powder as a co-material, if necessary. The common material has an effect of suppressing the sintering of the conductor material in the firing step.

  When the step between the green sheet and the electrode pattern adversely affects the lamination process, the electrode pattern 12a is formed after or before the electrode pattern 12a having a predetermined pattern is formed on the surface of the green sheet 10a by the printing method. A blank pattern having substantially the same thickness as that of the electrode pattern 12a may be formed on the surface of the green sheet 10a on which no is formed.

After forming the green laminate , as shown in FIG. 3A, the green sheet 10a (inner layer green sheet) on which the internal electrode pattern 12a is formed is peeled from the carrier sheet 20 to form the internal electrode pattern 12a. A plurality of green sheets 10a that are not stacked are stacked on an outer layer green sheet (outer layer green sheet). Then, as shown in FIG. 3 (B), this operation is repeated, and the inner layer green sheets are alternately stacked up to the desired number of layers, and finally the outer layer green sheets are stacked in the stacking direction. A green laminate having a configuration in which the green sheet for the inner layer is sandwiched between the green sheets for the outer layer from both sides is produced.

  Thereafter, the green laminate is finally pressurized. The pressure at the time of final pressurization is preferably 10 to 200 MPa. Moreover, 40-100 degreeC is preferable for heating temperature. The laminate is cut into a predetermined size to obtain a green chip. The obtained green chip is heat-treated (solidified and dried).

Solidification drying The solidification drying treatment is performed in a reduced-pressure atmosphere in which the atmospheric pressure is less than atmospheric pressure, and the oxygen partial pressure in the atmosphere is 10 Pa or more and less than the oxygen partial pressure in air at atmospheric pressure. . The atmospheric pressure is preferably 40 Pa or more and less than atmospheric pressure, and more preferably 50 to 5000 Pa. Moreover, it is preferable that oxygen partial pressure is 1000 Pa or less, and it is more preferable that it is 10-1000 Pa.

  If the atmospheric pressure is too low, the variation in peel strength of the chip after sintering tends to increase. On the other hand, if it is too high, organic components other than the binder resin (solvent and plasticizer) tend not to be sufficiently removed. As a result, in the binder removal process, these organic components are rapidly removed, and many cracks tend to occur. In addition, since the shape retention of the tip is lowered, the efficiency during polishing tends to be lowered.

  If the oxygen partial pressure is too low, organic components (solvents and plasticizers) other than the binder resin tend not to be sufficiently removed. As a result, in the binder removal process, these organic components are rapidly removed, and many cracks tend to occur. In addition, the shape retention of the tip tends to decrease. On the contrary, if the oxygen partial pressure is too high, decomposition of the binder resin tends not to be suppressed.

  In order to set the atmospheric pressure and the oxygen partial pressure within the above ranges, the inside of the heating device used in the solidification drying process may be depressurized. For example, an inert gas may be introduced into the device to introduce oxygen. It may be purged.

  Specific conditions for the solidification drying process may be set as follows, for example.

  The holding temperature is preferably 140 to 180 ° C., and the holding time is preferably 2 to 10 hours. If the holding temperature is low or the holding time is too short, many cracks tend to occur in the binder removal step. Conversely, if the holding temperature is high or the holding time is too long, the decomposition of the binder resin cannot be suppressed, and not only cracks are generated in the manufacturing process, but also cracks induced during use as a product tend to increase. is there.

  The amount of carbon remaining in the green chip (organic component) is preferably 3.5 to 5.0% by weight, more preferably 4.0%, with respect to 100% by weight of the green chip after solidification and drying. -4.5 wt%. If the amount of residual carbon is too small, decomposition of the binder resin cannot be suppressed, and cracks are not only generated in the manufacturing process but also cracks induced during use as a product tend to increase. On the other hand, when the amount of residual carbon is too large, cracks induced at the time of binder removal tend to increase. In addition, the shape retention of the tip tends to decrease.

  Thus, by controlling the atmospheric pressure and the oxygen partial pressure in the solidification drying step within the above ranges, organic components other than the binder resin can be removed while suppressing the decomposition of the binder resin. That is, the green chip can be cured in a state where sufficient adhesion between the layers is ensured. As a result, it is possible to suppress generation of direct cracks or generation of microcracks that become a source of cracks that are manifested when the product is used in a polishing process described later. In addition, the occurrence of cracks during binder removal can be suppressed.

After polishing solidified drying and polishing to the green chip. The polishing method is not particularly limited, and it does not matter whether it is dry or wet. In this embodiment, wet barrel polishing is performed. In wet barrel polishing, green chips are put into a barrel container together with media and water, and polishing is performed for a predetermined time with a known barrel machine. As the medium, balls or beads such as alumina or zirconia may be used. When the wet barrel polishing is used as in the present embodiment, since the polishing can be performed with a weak impact force, defects in the green chip can be made difficult to occur. Also, crack growth can be prevented when liquid enters the green chip.

  Moreover, since the component which lowers | hangs the hardness of green chips, such as a solvent and a plasticizer, is removed from the green chip after solidification drying by said solidification drying, grinding | polishing can be performed efficiently.

A binder removal treatment is performed after polishing such as binder removal and firing . In this embodiment, since Ni is contained as a conductor material for forming the internal electrode layer 12, the atmosphere in the debinding process is preferably an air atmosphere or a nitrogen 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.

  Subsequently, in the present embodiment, the green chip is preferably fired at a temperature of 1000 to 1400 ° C. If the firing temperature is too low, densification of the dielectric layer 10 after sintering tends to be insufficient and the capacitance tends to be insufficient, and if it is too high, the dielectric layer 10 will be overfired, resulting in a direct current electric field. There is a tendency that the change with time of the capacitance during application tends to increase.

In the present embodiment, the firing atmosphere is preferably a reducing atmosphere, and the green chip is preferably fired in an atmosphere having an oxygen partial pressure of 10 ⁻¹⁰ to 10 ⁻² Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode layer 12 may be abnormally sintered and may be interrupted. Conversely, if the oxygen partial pressure is too high, the internal electrode layer 12 tends to oxidize. There is. As the atmospheric gas, for example, a humidified mixed gas of N ₂ and H ₂ may be used.

  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.

In this embodiment, it is preferable to anneal the element body after firing. Annealing is a process for re-oxidizing the dielectric layer 10, whereby the accelerated life of the insulation resistance (IR) can be remarkably increased, and the reliability is improved. The annealing is preferably performed under an oxygen partial pressure higher than the reducing atmosphere at the time of firing. Specifically, the annealing is preferably performed in an atmosphere having an oxygen partial pressure of preferably 10 ^{−2 to} 100 Pa. If the oxygen partial pressure during annealing is too low, it is difficult to re-oxidize the dielectric layer 10, while if it is too high, the internal electrode layer 12 tends to be oxidized and insulated.

  In the present embodiment, the holding temperature or maximum temperature during annealing is preferably set to a temperature of 1200 ° C. or lower. The holding time is preferably 0.5 to 4 hours. 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. The binder removal treatment, firing and annealing may be performed continuously or independently.

The sintered body (element body 4) thus obtained is subjected to end face polishing by, for example, barrel polishing, sand blasting or the like, and terminal electrode paint is baked to form a base electrode (baked layer). The terminal electrode coating condition is preferably set, for example, to about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N ₂ and H ₂ . Then, plating is performed on the baking layer to form the terminal electrodes 6 and 8. At this time, if there is a microcrack in the element body, the plating solution may enter the microcrack, and the microcrack may progress (grow) and become apparent when the product is used. . According to the invention according to the present embodiment, even if the terminal electrode is composed of a baking layer and a plating layer, cracks induced by the penetration of the plating solution as described above can be effectively suppressed. In addition, what is necessary is just to prepare the coating material for terminal electrodes like the above-mentioned coating material for internal electrode layers.

  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.

  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, in the above-described embodiment, the electrode pattern is directly formed on the surface of the green sheet by a printing method. However, the electrode pattern may be formed on the surface of the green sheet by using a transfer method.

  Alternatively, the green sheet 10a on which the electrode pattern 12a is formed may be laminated on the outer layer green sheet via an adhesive layer. Alternatively, a green body block 10a on which the electrode pattern 12a is formed may be laminated to form a laminated body block having a predetermined number of laminated layers, which may be laminated via an adhesive layer.

  In the above-described embodiment, the two-terminal multilayer ceramic capacitor having the terminal electrodes 6 and 8 is manufactured. However, the present invention may be applied to the manufacture of multi-terminal multilayer electronic components.

  Furthermore, the method according to the present invention is not limited to a method for manufacturing a multilayer ceramic capacitor, but can also be applied as a method for manufacturing other multilayer electronic components.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
Preparation of paint for green sheet BaTiO ₃ system powder as ceramic powder: 100 parts by weight, acrylic resin as binder resin: 4.8 parts by weight, ethyl acetate as solvent: 100 parts by weight, toluene as solvent: 4 Part by weight and dioctyl phthalate (DOP) as plasticizer: 2.4 parts by weight were slurried with a ball mill to obtain a green sheet paint.

100 parts by weight of Ni particles having an average particle diameter of the internal electrode layer coating of 0.2 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol), 10 parts by weight of butyl carbitol, Was kneaded with three rolls and slurried to obtain a coating for the internal electrode layer.

Formation of Green Sheet and Green Laminate Using the above green sheet coating material, a green sheet having a thickness of 3.0 μm was formed on a PET film and dried to prepare a green sheet 10a. As drying conditions, the temperature in the drying furnace was 60 ° C. to 70 ° C., and the drying time was 2 minutes. Next, an electrode pattern 12a was formed on the surface of the formed green sheet. The electrode pattern 12a was formed with a thickness of 1.5 μm by the printing method using the internal electrode layer coating material. Subsequently, by the method shown in FIG. 3, the green sheets 10a (inner layer green sheets) on which the electrode patterns 12a were formed were laminated on the outer layer green sheets to form a green laminate. This green laminate was cut into a predetermined size to obtain a green chip.

Solidification drying Next, the obtained green chip was solidified and dried. Solidification drying was performed at a temperature rising rate: 50 ° C./hour, a holding temperature: 180 ° C., and a holding time: 10 hours. The atmospheric pressure and oxygen partial pressure during solidification drying were set to the pressures shown in Table 1.

Wet barrel polishing Next, wet barrel polishing was performed on the solidified and dried green chip. The green chip was put into a barrel container together with media and water, and barrel-polished by a known barrel machine for 1.0 hour. The green chip after barrel polishing was washed with water and dried.

Binder removal, firing, annealing Next, the green chip after barrel polishing was subjected to binder removal treatment.
The binder removal was performed at a temperature rising rate: 15 ° C./hour, a holding temperature: 600 ° C., a holding time: 2 hours, and an atmospheric gas: in the air.

Next, the green chip after the binder removal treatment was fired and annealed (heat treatment) to produce a chip-shaped sintered body. Firing is performed at a heating rate of 300 ° C./hour, a holding temperature of 1200 ° C., a holding time of 2 hours, a cooling rate of 200 ° C./hour, and an atmospheric gas: a mixed gas of N ₂ and H ₂ (5%). went.

Annealing (reoxidation) was performed at a temperature rising rate: 300 ° C./hour, a holding temperature: 1050 ° C., a holding time: 2 hours, a cooling rate: 300 ° C./hour, and an atmospheric gas: N ₂ gas. The humidification of the atmospheric gas was performed using a wetter at a water temperature of 0 to 75 ° C.

  Next, after polishing the end face of the chip-shaped sintered body by barrel polishing, a Cu paste is applied to the end portion, and after that, after baking treatment, Ni plating and Sn plating treatment are performed to form the terminal electrode. The multilayer ceramic capacitor sample shown in FIG. 1 was obtained. In addition, the size after baking of each chip | tip was 3.2 mm x 1.6 mm x 0.6 mm.

Implement samples of a multilayer ceramic capacitor obtained cracking incidence to the test substrate was subjected to heat shock test by cooling after heating to about 240 ° C.. About the sample after a thermal shock test, the crack generation rate was evaluated. The thermal shock test was conducted in order to remarkably generate cracks generated in the capacitor manufacturing process and cracks induced during or during use as a product.

  The appearance of 1 million capacitor samples after the test was observed with an optical microscope to confirm the presence or absence of cracks, and the crack generation rate (ppm) was calculated. The results are shown in Table 1.

  In the appearance observation, when a linear crack is observed in the direction parallel to the laminated surface at the boundary portion between the inner layer and the outer layer or at the interface between the dielectric layer and the inner electrode layer, such a crack is removed. Classified as crack A. It is presumed that the crack A is a crack mainly generated at the time of binder removal. In addition, when cracks were observed obliquely with respect to the laminated surface at the boundary between the inner layer and the outer layer or at the interface between the dielectric layer and the inner electrode layer, such cracks were classified as crack B. It is presumed that the crack B mainly includes cracks induced during use or during use in addition to cracks generated in the capacitor manufacturing process.

Peel strength The peel strength of the obtained multilayer ceramic capacitor sample was evaluated. First, the peel strength was measured for 50 samples of the obtained multilayer ceramic capacitor, and the average value was taken as the peel strength. The peel strength was measured as follows. In the capacitor sample, a part of one of the surfaces (4a, 4b) where the internal electrode is exposed is fixed so as to contact the jig, and the other surface of the surface where the internal electrode is exposed A load was applied to the sample at a speed of 1 mm / min in a direction parallel to the laminated surface. That is, a shearing force is applied in the longitudinal direction of the capacitor sample. The strength at the time of starting to peel was defined as the peel strength. The results are shown in Table 1.

Evaluation 1
From Table 1, if the oxygen partial pressure during solidification drying is too low (Sample No. 1), the peel strength is high, but organic components (solvents and plasticizers) other than the binder resin are not sufficiently removed. It is considered that a large amount of A occurred.

  In addition, when the atmosphere at the time of solidification drying is in the air (Sample No. 5), in addition to low peel strength, the binder resin in the chip is decomposed and removed at the time of solidification drying, resulting in adhesion between each layer. In particular, the adhesion between the outer layer and the inner layer was lowered. As a result, it is considered that micro-cracks or the like were generated inside the chip during barrel polishing, and this was manifested as cracks by the thermal shock test.

  Moreover, although the atmospheric pressure at the time of solidification drying is within the range of the present invention, but the oxygen partial pressure is outside the range of the present invention (Sample No. 6), although the peel strength is large, the oxygen partial pressure is too low. Like Sample No. 1, there was a tendency for crack A to occur.

  On the other hand, when the atmospheric pressure and oxygen partial pressure during solidification drying are within the scope of the present invention (Sample Nos. 2 to 4), the binder resin in the chip remains without being decomposed, and the solvent or plastic The agent has been removed. As a result, since it was used for barrel polishing in a state where the adhesion between each layer was sufficiently secured, it was considered that microcracks were not generated during barrel polishing, and cracks B were hardly generated even after the thermal shock test. . Further, it is considered that almost no crack A occurred. Moreover, since the solvent and the plasticizer are sufficiently removed in the solidification drying, the polishing efficiency is improved.

Example 2
A multilayer ceramic capacitor was produced and evaluated in the same manner as in Example 1 except that the amount of carbon remaining in the chip after solidification drying was changed to the amount shown in Table 2 in the same manner as Sample No. 2 in Example 1. . The results are shown in Table 2.

Evaluation 2
From Table 2, it was confirmed that when the amount of residual carbon was less than the preferred range of the present invention (sample numbers 11 and 12), cracks B were mainly observed and the crack generation rate tended to be slightly higher. This is thought to be due to a slight increase in the decomposition of the binder resin.

  Further, when the amount of residual carbon was larger than the preferred range of the present invention (Sample No. 17), crack A was mainly observed. This is probably because many organic components other than the binder resin remained, and these organic components were rapidly removed in the binder removal step. Therefore, the amount of residual carbon is preferably within the preferred range of the present invention.

2 ... Multilayer ceramic capacitor 4 ... Capacitor element body 6, 8 ... Terminal electrode 10 ... Dielectric layer 10a ... Green sheet 12 ... Internal electrode layer 12a ... Electrode pattern 20 ... Carrier sheet

Claims (5)

A method of manufacturing a multilayer electronic component having an element body in which a ceramic layer and an electrode layer are laminated,
Cutting a green laminate in which a green sheet and an electrode pattern are laminated to obtain a green chip containing at least a binder resin, a solvent, and a plasticizer;
Heat-treating the green chip in a reduced-pressure atmosphere having a pressure lower than atmospheric pressure and an oxygen partial pressure in the atmosphere being 10 Pa or higher and lower than an oxygen partial pressure in air at atmospheric pressure;
Polishing the green chip after heat treatment;
A step of removing the binder and baking the green chip after polishing to obtain the element body.   The method for manufacturing a multilayer electronic component according to claim 1, wherein an atmospheric pressure in the reduced-pressure atmosphere is 40 Pa or more and less than atmospheric pressure.   3. The multilayer electronic component according to claim 1, wherein the amount of carbon remaining in the green chip is 3.5 to 5.0% by weight with respect to 100% by weight of the green chip after heat treatment. Method.   The method for manufacturing a multilayer electronic component according to claim 1, wherein the green chip is polished by wet barrel polishing. Further comprising forming a terminal electrode on the surface of the element body;
The terminal electrode is composed of a baking layer formed by baking a terminal electrode coating applied to the surface of the element body, and a plating layer formed on the baking layer. The manufacturing method of the multilayer electronic component in any one.

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