JP2005167290A - Method of manufacturing laminated ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a small laminated ceramic electronic component, which has high reliability and no structure defect, and in which an internal electrode and ceramic layers can be made thin. <P>SOLUTION: In the method of manufacturing the laminated ceramic electronic component, which obtains a laminated body comprising a plurality of laminated ceramic layers and an internal electrode which is positioned between the ceramic layers and is obtained by sintering metal powder, the mean particle diameter of the ceramic material powder is 25-250 nm, the mean particle diameter of the conductive metal powder is 10-200 nm, the thickness of the ceramic layer is 3 μm or less, the thickness of the internal electrode layer is 0.2-0.7 μm, and the mean particle diameter of a ceramic grain which constitutes the ceramic layers is greater than 0.5 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

 The present invention relates to a method for manufacturing a multilayer ceramic electronic component such as a multilayer ceramic capacitor having an internal electrode made of a base metal such as nickel or a nickel alloy.

   Conventionally, various laminated ceramic electronic components including a plurality of laminated ceramic layers and internal electrodes formed between the ceramic layers have been put into practical use. A typical example is a multilayer ceramic capacitor using a ceramic dielectric as a ceramic layer.

  Conventionally, in this multilayer ceramic capacitor, it has been necessary to fire a dielectric material at a high temperature of about 1300 ° C. in the air, so that noble metals such as palladium and platinum or alloys thereof have been used as internal electrodes. However, these electrode materials are very expensive, the ratio of the electrode material to the product cost is high, and it is difficult to reduce the cost.

  In order to solve the above problems, the internal electrode material of the multilayer ceramic capacitor has been made to be a base metal, and a dielectric material in consideration of reduction resistance that can be fired in a neutral or reducing atmosphere so as not to oxidize the electrode during firing. Various developments have been made. Such base metal internal electrode materials include cobalt, nickel, copper, etc., but nickel is mainly used from the viewpoint of cost and oxidation resistance.

  Currently, multilayer ceramic capacitors are required to be smaller and have larger capacities. Ceramic dielectric materials are being studied for higher dielectric constants and thinner layers. At the same time, electrode materials are being made thinner. Is being considered.

  The internal electrode of the multilayer ceramic capacitor is generally formed by applying a paste containing metal powder by a printing method such as screen printing. For example, when nickel powder is used as the metal powder contained in such a paste, a nickel powder having a mean particle diameter of more than 0.25 μm produced by a liquid phase method or a chemical vapor phase method is often used. Has been. However, when the particles are large in this way, it is difficult to reduce the thickness of the internal electrode.

  Further, when nickel powder having an average particle diameter of about 0.25 μm is used, it is necessary to set the electrode thickness to 0.8 μm or more in order to bring out the dielectric characteristics of the dielectric ceramic.

  Further, thinning the ceramic dielectric layer is the most effective means for increasing the capacitance of the multilayer ceramic capacitor. For example, the thickness of the ceramic layer is less than the thickness of the internal electrode of 0.8 μm. When the thickness is 3 μm or less, a fatal structural defect such as delamination frequently occurs due to a difference in contraction rate between the electrode and the ceramic.

  In addition, in a multilayer ceramic capacitor having high dielectric constant F characteristics, E characteristics, temperature compensation SL characteristics, and CG characteristics as defined by JIS, if the thickness of the ceramic layer is made as thin as 3 μm or less, the electrical characteristics In some cases, a high performance multilayer ceramic capacitor cannot be obtained.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a technology capable of reducing the thickness of internal electrodes and ceramic layers without causing structural defects in a multilayer ceramic electronic component such as a multilayer ceramic capacitor. It is intended to provide with reliability.

To achieve the above object, the present invention comprises a step of mixing a ceramic raw material powder, an organic binder and a solvent to prepare a ceramic slurry, a step of forming the ceramic slurry to obtain a ceramic green sheet, and the ceramic green sheet. A step of forming a conductive paste film containing conductive metal powder, a step of laminating the ceramic green sheet and the ceramic green sheet formed with the conductive paste film, and pressing to obtain a raw laminate And a step of heating the raw laminate in a N ₂ atmosphere to remove the binder, and a step of firing the removed binder, a plurality of laminated ceramic layers, and the ceramic layers And a laminated body including an internal electrode obtained by sintering metal powder. In the manufacturing method of the Mick electronic component, the average particle diameter of the ceramic raw material powder is 25 to 250 nm, the average particle diameter of the conductive metal powder is 10 to 200 nm, and the thickness of the ceramic layer is 3 μm or less, The thickness of the internal electrode layer is 0.2 to 0.7 μm, and the average grain size of the ceramic grains constituting the ceramic layer exceeds 0.5 μm.

  In addition, a representative form of the ceramic electronic component further includes external electrodes formed on the opposing end faces of the laminate, the ceramic layer is made of a ceramic dielectric, and the plurality of internal electrodes are Each of the outer edges is formed so as to be electrically connected to any one of the external electrodes, thereby forming a multilayer ceramic capacitor.

  Further, the metal powder is made of a base metal, and in particular, the base metal is a metal containing nickel.

  Furthermore, the internal electrode is formed through a process in which a paste containing the metal powder is applied by a printing method.

  The ceramic grains constituting the ceramic layer have a uniform composition and crystal system in each ceramic grain, and are composed of one kind of ceramic grains having the same composition and crystal system.

  The ceramic grains constituting the ceramic layer are characterized by being composed of two or more kinds of ceramic grains having a uniform composition and crystal system in each ceramic grain and having different compositions.

  According to the present invention, since the thickness of the internal electrode is 0.2 to 0.7 μm, it is possible to suppress the occurrence of delamination of the multilayer ceramic electronic component even when the thickness of the ceramic layer is reduced to 3 μm or less. it can. Therefore, when the present invention is applied to a multilayer ceramic capacitor, it is extremely effective in reducing the size and capacity of the multilayer ceramic capacitor.

  Further, since the average grain size of the ceramic grains constituting the ceramic layer exceeds 0.5 μm, the necessary dielectric characteristics can be ensured even when the thickness of the ceramic layer is as thin as 3 μm or less.

  In the present invention, a paste containing metal powder is used to form the internal electrode. When the metal powder in the paste has an average particle size in the range of 10 to 200 nm, Since the packing density and smoothness of the metal powder are improved, even if the internal electrode is as thin as 0.2 to 0.7 m as described above, the electrical characteristics such as the dielectric characteristics of the ceramic constituting the ceramic layer Thus, it is possible to realize a coverage that can sufficiently draw out and sufficiently fulfill the function as an internal electrode. Further, since the internal electrode is formed, a printing method such as screen printing can be applied without any problem, so that the internal electrode forming process can be efficiently performed.

  When a powder made of a base metal is used as the metal powder described above, the material cost can be reduced, and when a metal containing nickel is used as the base metal, higher oxidation resistance is expected than copper. can do.

  In addition, when ceramic raw material powder having an average particle size of 25 to 250 nm is used, the ceramic filling rate and smoothness of the ceramic layer are improved, so that even a thin ceramic layer of 3 μm or less has high reliability. It becomes possible.

  Thus, by optimizing the combination of the average particle size of the metal powder, the thickness of the internal electrode, the average particle size of the ceramic raw material powder, the average particle size of the ceramic grain, and the ceramic layer thickness, the thin film multilayer ceramic is first used. It is possible to manufacture parts, especially small and large capacity multilayer ceramic capacitors.

  Further, the ceramic grains constituting the ceramic layer have a uniform composition and crystal system within each ceramic grain, and the same composition and crystal system, or two or more different types of ceramic grains are used. Thus, a highly reliable multilayer ceramic electronic component having excellent electrical characteristics can be manufactured.

  Hereinafter, an embodiment when the present invention is applied to a multilayer ceramic capacitor 1 having a structure as shown in FIG. 1 will be described.

  Referring to FIG. 1, a laminated ceramic capacitor 1 includes a laminated body 3 having a ceramic layer 2 made of a plurality of laminated ceramic dielectrics, and first and second end faces 4 and 5 of the laminated body 3. First and second external electrodes 6 and 7 are provided, respectively. The multilayer ceramic capacitor 1 constitutes a cuboid chip type multilayer ceramic electronic component as a whole.

  In the laminated body 3, the first internal electrodes 8 and the second internal electrodes 9 are alternately arranged. The first inner electrode 8 is connected to a plurality of specific interfaces between the ceramic layers 2 with each end edge exposed to the first end face 4 so as to be electrically connected to the first outer electrode 6. And the second internal electrode 9 is formed between the ceramic layers 2 with each edge exposed to the second end face 5 so as to be electrically connected to the second external electrode 7. Each is formed along a specific plurality of interfaces.

  In order to manufacture the multilayer ceramic capacitor 1, a main raw material such as barium titanate, that is, a ceramic raw material powder and an additive for the purpose of property modification are prepared as starting materials. As the ceramic raw material powder, those having an average particle diameter of 25 to 250 nm are preferably used for the reasons described later, for example, by adjusting the calcination temperature or using a wet synthesis method. The main raw material ceramic raw material powder is prepared by wet mixing of oxides and carbonates known as conventional solid phase methods or wet synthesis known as hydrothermal synthesis and hydrolysis methods so as to have the desired composition What was dried and calcined is used.

  These raw material powders and additives are weighed in predetermined amounts, and are mixed into a mixed powder through wet mixing. More specifically, each additive is added and wet-mixed by a method of mixing with the ceramic raw material powder in the form of oxide powder or carbonate powder. At this time, in order to make each additive soluble in a solvent, it may be an alkoxide or a compound such as acetyl acetate or metal soap. In addition, a method of applying a solution containing each additive component to the surface of the ceramic raw material powder and performing a heat treatment is also possible.

  Next, a ceramic slurry is prepared by adding an organic binder and a solvent to the above-mentioned mixed powder, and a ceramic green sheet to be the dielectric ceramic layer 2 is produced using this ceramic slurry. The thickness of the green sheet is set so that the thickness after firing is 3 μm or less for the reason described later.

  Next, a conductive paste film to be the internal electrodes 8 and 9 is formed on a specific ceramic green sheet by a printing method such as screen printing. The thickness of the conductive paste film is set so that the thickness after firing is 0.2 to 0.7 μm.

  The above-mentioned paste constituting the conductive paste film contains a metal powder, a binder and a solvent, and it is preferable to use a metal powder having an average particle diameter of 10 to 200 nm for the reason described later. As an example, a paste containing a solvent such as Ni powder, ethyl cellulose binder and terpineol is used. This paste is carefully prepared using, for example, a three-roll mill in order to dissolve or prevent the aggregation of Ni powder having an extremely small particle diameter of 10 to 200 nm and to disperse them well.

  The metal powder mentioned above, more specifically Ni powder, can be suitably produced by, for example, chemical vapor deposition, hydrogen arc discharge, or gas evaporation.

  In chemical vapor deposition, nickel chloride is heated to evaporate, and the resulting nickel chloride vapor is reacted in contact with hydrogen at a predetermined temperature while being conveyed with an inert gas, thereby producing nickel powder. It is a method to do. The nickel powder is collected by cooling the reaction gas containing the nickel powder.

  The hydrogen arc method is a method of generating nickel fine powder from a gas phase by performing arc discharge in an atmosphere containing hydrogen gas and melting and evaporating nickel. When supersaturated hydrogen is dissolved in molten nickel by the heat of the arc or plasma, a local high temperature state is formed when hydrogen is released from the molten nickel, which promotes nickel evaporation and releases nickel vapor. Is done. Nickel fine powder is produced by agglomerating and cooling the nickel vapor.

  In the gas evaporation method, a nickel ingot is melted by a heating means such as high frequency induction heating in a container filled with an inert gas (Ar, He, Xe, etc.) and heated until nickel vapor is generated. This is a method for producing nickel fine powder by cooling and solidifying by bringing vapor into contact with an inert gas in the atmosphere.

  Next, a plurality of ceramic green sheets including the ceramic green sheet on which the conductive paste film is formed as described above are stacked, pressed, and then cut as necessary. In this way, a plurality of ceramic green sheets and a conductive paste film that becomes a plurality of internal electrodes 8 and 9 formed between the ceramic green sheets, respectively, are laminated, and a conductive material that becomes the internal electrodes 8 and 9 is laminated. The laminated body 3 in a raw state in which each edge of the conductive paste film is exposed to the end face 4 or 5 is produced.

  Next, the laminate 3 is fired in a reducing atmosphere. At this time, for the reasons described later, the firing conditions are set so that the average grain size of the fired ceramic grains constituting the ceramic layer 2 exceeds 0.5 μm.

  Next, the first and second end faces 4 and 4 of the laminate 3 are electrically connected to the exposed edges of the first and second internal electrodes 8 and 9 in the fired laminate 3, respectively. First and second external electrodes 6 and 7 are formed on 5 respectively.

The material composition of the external electrodes 6 and 7 is not particularly limited. Specifically, the same material as the internal electrodes 8 and 9 can be used. Also, for example, a sintered layer of various conductive metal powders such as Ag, Pd, Ag-Pd, Cu, Cu alloy, or the conductive metal powder and B ₂ O ₃ —Li ₂ O—SiO ₂ —BaO. configured system, B ₂ O ₃ -SiO ₂ -BaO-based, Li ₂ O-SiO ₂ -BaO-based, the sintered layer containing a combination of the various glass frit, such as B ₂ O ₃ -SiO ₂ -ZnO system be able to. The material composition of the external electrodes 6 and 7 is appropriately selected in consideration of the application and use place of the multilayer ceramic capacitor 1.

  As described above, the external electrodes 6 and 7 may be formed by applying and baking a metal powder paste as a material on the fired laminate 3. However, the external electrodes 6 and 7 may be formed on the laminate 3 before firing. It may be formed by being applied to and baked simultaneously with the firing of the laminate 3.

Thereafter, if necessary, the external electrodes 6 and 7 are respectively covered with plating layers 10 and 11 made of Ni, Cu, Ni—Cu alloy or the like.
Furthermore, second plating layers 12 and 13 made of solder, tin or the like may be formed on these plating layers 10 and 11.

  In the present invention, the thickness of the internal electrodes 8 and 9, and in the embodiment according to the present invention, to form the Ni powder and ceramic layer 2 contained in the paste used to form the internal electrodes 8 and 9. The above-mentioned ranges are defined for the average particle diameter of the ceramic raw material powder before sintering and the ceramic grain constituting the ceramic layer, and the thickness of the ceramic layer 2. In the present specification, the average particle size means a 50% particle equivalent diameter (D50) in a number-based particle size distribution obtained by image analysis of powder and ceramic grain electron micrographs.

  In the present invention, the thickness of the internal electrodes 8 and 9 is defined as 0.7 μm or less because when the thickness exceeds 0.7 μm, the thickness of the ceramic layer 2 is reduced to 3 μm or less. This is because the occurrence of delamination caused by the difference in shrinkage between 8 and 9 and the ceramic layer 2 is inevitable. In other words, by reducing the thickness of the internal electrodes 8 and 9 to 0.7 μm or less, the thickness of the ceramic layer 2 can be reduced to 3 μm or less without any problem as described above. Can contribute to large capacity.

  On the other hand, the thickness of the internal electrodes 8 and 9 is defined to be 0.2 μm or more. When the thickness is less than 0.2 μm, nickel contained in the internal electrodes 8 and 9 reacts with the ceramic contained in the ceramic layer 2 at the time of firing. This is because nickel is oxidized or deoxidation is caused by this oxidation, and the function as an internal electrode cannot be performed.

  Moreover, the average grain size of the ceramic grains of the ceramic dielectric exceeds 0.5 μm, and the ceramic grain diameter in the thickness direction of the ceramic layer is defined to be equal to or smaller than the thickness of the ceramic layer for the following reason.

  That is, when the ceramic layer has a thickness of 3 μm or less, if the average grain size of the ceramic grains is 0.5 μm or less, the multilayer ceramic capacitor is fired and the difference in thermal shrinkage between the internal electrode layer and the ceramic layer during cooling is reduced. This is because the dielectric characteristics of the ceramic deteriorate due to the thermal stress caused by the above. By selecting the firing temperature and ceramic composition under appropriate conditions, when the average particle size of the ceramic exceeds 0.5 μm, the dielectric properties of the ceramic layer improve, and the multilayer ceramic capacitor can be made smaller and larger in capacity. Can contribute to

  Further, when the grain size of the ceramic grains exceeds the thickness of the ceramic layer, delamination is generated by firing, which is not preferable. However, if the grain size of the ceramic grain in the thickness direction of the ceramic layer is less than or equal to the thickness of the ceramic layer, even if the grain size of the ceramic grain in the in-plane direction within the ceramic layer is greater than or equal to the thickness of the ceramic layer, Is no problem.

  Further, in the case of a multilayer ceramic capacitor having a high dielectric constant F characteristic or E characteristic defined by JIS, the ceramic grains constituting the ceramic layer have a uniform composition and crystal system within each ceramic grain. And it is preferable to consist of one kind of ceramic grains having the same composition and crystal system. Thereby, the dielectric constant of the ceramic layer is increased and a highly reliable multilayer ceramic capacitor can be obtained.

  In the case of a multilayer ceramic capacitor having SL characteristics or CG characteristics for temperature compensation defined by JIS, the ceramic grains constituting the ceramic layer have a uniform composition and crystal system in each ceramic grain, and It is preferably made of two or more kinds of ceramic grains having different compositions. As a result, the Q of the ceramic layer is increased and a flat dielectric constant temperature characteristic is obtained.

  The average particle diameter of the Ni powder used for the internal electrode is preferably limited to 10 to 200 nm for the following reason.

  That is, when the average particle size of the Ni powder is less than 10 nm, it becomes difficult to produce a paste having a viscosity applicable to a printing method such as screen printing. Moreover, even if screen printing is performed using such a high-viscosity paste, it is difficult to form a conductive paste film that will be the internal electrodes 8 and 9 smoothly due to the high viscosity, which may cause blurring or pinning. Holes are generated, resulting in lower coverage and electrode breakage.

  On the other hand, when the average particle diameter of the Ni powder exceeds 200 nm, the nickel particles are too large, so that it becomes difficult to smoothly form the conductive paste film that becomes the internal electrodes 8 and 9, and the coverage is reduced. End up. Further, the unevenness at the interface between the internal electrodes 8 and 9 and the ceramic layer 2 becomes large.

  Next, the average particle size of the ceramic raw material for forming the ceramic element is preferably limited to 25 to 250 nm for the following reason.

  That is, when the average particle size of the ceramic raw material is less than 25 nm, the ceramic raw material powder exhibits strong agglomeration and a homogeneous green sheet cannot be obtained, and when the element thickness is 3.0 μm, many short-circuit defects are caused. On the other hand, when it exceeds 250 nm, the smoothness of the green sheet surface is deteriorated, and the unevenness at the interface between the internal electrodes 8 and 9 and the ceramic layer 2 is increased.

  The embodiment described above is for the case where the multilayer ceramic electronic component is a multilayer ceramic capacitor. However, for example, the multilayer ceramic electronic component includes substantially the same structure, for example, other multilayer ceramic electronic components such as a multilayer ceramic substrate. Also, the present invention can be applied.

  Further, the metal powder contained in the paste for forming the internal electrode includes nickel powder as described above, nickel alloy, other base metal such as copper or copper alloy, and noble metal powder. Also good.

Next, the present invention will be described in detail based on more specific examples.
In addition, the form which can be implemented in the range of this invention is not limited only to such an Example.

  (Embodiment 1) The multilayer ceramic capacitor to be manufactured in this embodiment is a multilayer ceramic capacitor having a structure as shown in FIG.

1. Preparation of sample: First, (Ba, Sr) TiO3 powders having different average particle diameters shown in Table 1 as ceramic raw material powders were prepared by hydrolysis. Table 2 shows the compositions of the ceramics used in the examples with the powders shown in Table 1 as the main raw materials. For each additive component, a solution containing the additive component was applied to the surface of (Ba, Sr) TiO ₃ and heat-treated at 500 ° C. In order to make each additive mentioned above soluble in an organic solvent this time, in addition to alkoxide, a compound such as acetylacetonate or metal soap was used. The ceramic raw material powder adjusted to the desired composition shown in Table 2 is then calcined, the calcining temperature is adjusted, and as shown in Table 3, ceramics having an average particle size of 15 nm, 25 nm, 200 nm, and 300 nm Raw materials were prepared.

  Next, an organic solvent such as a polyvinyl butyral binder and ethanol was added to the powder of each barium titanate ceramic composition shown in Table 3, and wet mixed by a ball mill to prepare a ceramic slurry. A ceramic green sheet was formed by applying a doctor blade method to the ceramic slurry. At this time, ceramic green sheets with thicknesses of 4.2 and 1.4 μm were prepared by adjusting the slit width of the doctor blade. The thicknesses of 4.2 μm and 1.4 μm in the ceramic green sheet correspond to the thicknesses of 3 μm and 1 μm in the ceramic layer after passing through the laminating step and the firing step, as can be seen from the evaluation results described later.

  On the other hand, spherical Ni powders having average particle diameters changed to 5 nm, 15 nm, 50 nm, 100 nm, 180 nm, and 250 nm were prepared. More specifically, among these Ni powders, those having an average particle size of 5 nm and 15 nm are prepared by the gas evaporation method described above, and those having an average particle size of 50 nm and 100 nm are prepared by the hydrogen arc discharge method, Samples having an average particle size of 180 nm and 250 nm were prepared by a chemical vapor phase method.

  Next, 42 wt% of each Ni powder and 6 wt% of an ethyl cellulose binder were dissolved in 94 wt% of terpineol, and 44 wt% of an organic vehicle and 14 wt% of terpineol were added, and then carefully dispersed and mixed by a three roll mill. To prepare a paste containing a well-dispersed Ni powder.

  Next, these Ni pastes were screen-printed on each of the ceramic green sheets described above to form a conductive paste film serving as an internal electrode. At this time, by changing the thickness of the screen pattern, samples each having a conductive paste film thickness of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm were prepared. The thicknesses of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm after drying the conductive paste film are determined by the laminating step and the firing step, as can be seen from the evaluation results described later. This corresponds to the thicknesses of 0.8 μm, 0.7 μm, 0.4 μm, 0.2 μm, and 0.1 μm in the internal electrode after the passage.

Next, a plurality of ceramic green sheets were laminated so that the side from which the above-described conductive paste film was drawn was alternated, and integrated by hot pressing. Thereafter, the integrated press body was cut into a predetermined size to obtain a raw chip as a raw laminate. This raw chip is heated to a temperature of 300 ° C. in an N ₂ atmosphere to burn the binder, and then consists of H ₂ —N ₂ —H ₂ O gas having an oxygen partial pressure of 10 ⁻⁹ to 10 ⁻¹² MPa. In a reducing atmosphere, firing was performed with a profile that was maintained for 2 hours at a firing temperature in the range of 1000 to 1200 ° C. shown in Table 4.

A silver paste containing B ₂ O ₃ —Li ₂ O—SiO ₂ —BaO-based glass frit was applied to both end faces of the fired laminate, and baked at a temperature of 600 ° C. in an N ₂ atmosphere. An electrically connected external electrode was formed.

The outer dimensions of the multilayer ceramic capacitor thus obtained are 5.0 mm in width, 5.7 mm in length, and 2.4 mm in thickness, and the thickness of the ceramic layer interposed between the internal electrodes is 3 μm or It was 1 μm. The total number of effective ceramic dielectric layers was 5, and the area of the counter electrode per layer was 16.3 × 10 ⁻⁶ m ² .

2. Evaluation of samples: Next, the obtained multilayer ceramic capacitor samples were evaluated for the multilayer structure, electrical characteristics, and reliability in the following manner.
The results are shown in Table 4. In addition, what added * mark to the sample number of Table 4 is outside the scope of the present invention.

  The average particle size of the dielectric ceramic contained in the obtained multilayer ceramic capacitor was determined by chemically etching the cross-section polished surface of the multilayer ceramic capacitor and observing it with a scanning electron microscope.

  The thicknesses of the internal electrode layer and the ceramic dielectric layer were determined by observing the cross-sectional polished surface of the multilayer ceramic capacitor with a scanning electron microscope.

  The delamination of the multilayer ceramic capacitor was visually determined by polishing a sample cross section and observing under a microscope, and the ratio of the number of samples with delamination to the total number of samples (delamination rate) was obtained.

  The covering area ratio (coverage) of the internal electrode was quantified by peeling the internal electrode surface of the sample, taking a microscopic photograph of a hole in the electrode surface, and performing image analysis processing.

  The following electrical characteristics were evaluated for the samples judged to be good as a result of the above structural evaluation.

  Capacitance (C) and dielectric loss (tan δ) were measured according to JIS C 5102 using an automatic bridge-type measuring device, and the relative dielectric constant (ε) was calculated from the obtained capacitance.

As a high-temperature load test, the time-dependent change of the insulation resistance was measured while applying a DC voltage of 10 kV / mm at a temperature of 150 ° C., and the failure occurred when the insulation resistance value (R) of each sample became 10 ⁵ Ω or less. As a result, the average life time until failure was obtained.

  In Table 4, samples A1 to A4 and A19 marked with * have an internal electrode thickness of 0.8 μm, and delamination occurs at a high ratio. Similarly, samples A17, A18 and A26, A27 marked with * have an internal electrode thickness of 0.1 μm, and delamination occurs at a high rate. The latter delamination is due to nickel oxidation. On the other hand, when the thickness of the internal electrode is in the range of 0.2 to 0.7 μm as in the samples A6 to A16 and A20 to A25, delamination does not occur or hardly occurs.

  Samples A15, A16, and A20 marked with * have an average grain size of ceramic grains of 0.5 μm or less. When the average grain size of the ceramic grains is small, the dielectric constant is very small compared to the above and the reliability is low. It can be seen that in a thin layer having an element thickness of 3 μm or less, the electrical characteristics deteriorate when the grain size of the ceramic grains is small.

  In sample A5, the diameter of the ceramic grains constituting the ceramic layer is equal to or greater than the thickness of the ceramic layer, and delamination occurs at a high ratio. On the other hand, in sample A8, the grain size of the ceramic grains constituting the ceramic layer is the same 3 μm in the thickness direction of the ceramic layer, and the size in the in-plane direction of the ceramic layer is 5 μm. As shown in Sample A8, even if the grain size of the ceramic grain in the in-plane direction of the ceramic layer is large, delamination is also possible if the grain size of the ceramic grain in the thickness direction of the ceramic layer is equal to or less than the thickness of the ceramic layer. There is no problem in terms of electrical characteristics.

  From the above results, when the thickness of the ceramic layer is 3 μm or less, the thickness of the internal electrode is 0.2 to 0.7 μm, the average grain size of the ceramic grains exceeds 0.5 μm, and the thickness of the ceramic layer It can be seen that when the grain size of the ceramic grains in the direction is equal to or less than the thickness of the ceramic layer, delamination is suppressed and the electrical characteristics of the ceramic are excellent.

Next, the characteristics of the nickel powder that can make the thickness of the internal electrode 0.2 to 0.7 μm without any problem, particularly the average particle diameter, will be described. In sample A21, the particle size of the nickel powder is 250 nm, and the coverage and reliability are reduced.
In sample A13, the particle diameter of the nickel powder is 5 nm, and the coverage is reduced and slight delamination occurs.

  On the other hand, like the samples A6 to A12 and A22 to A25, by setting the average particle size of the nickel powder to 10 to 200 nm, the coverage is less lowered and the reliability is excellent.

  Next, the average particle diameter of the ceramic raw material powder before firing for forming the ceramic layer will be described. In Samples A12 and A25, the average particle size of the ceramic raw material powder is 300 nm, which results in a decrease in coverage and a decrease in reliability. In Samples A13, A14 and A22, the average particle size of the ceramic raw material powder is 15 nm, and slight delamination is observed.

  On the other hand, in samples A6 to A11, A23, and A24, by making the average particle size of the ceramic raw material powder 25 to 250 nm, there is no delamination and excellent dielectric properties can be obtained.

  The ceramic grains constituting the ceramic layer of the multilayer ceramic capacitor were observed and analyzed with a transmission analytical electron microscope. Further, the ceramic constituting the ceramic layer was pulverized and subjected to powder X-ray diffraction analysis. The obtained diffraction pattern was subjected to Rietveld analysis to identify the crystal phase. As a result, it was confirmed that each ceramic grain had a uniform composition and crystal system, and consisted of one kind of ceramic grain having the same composition and crystal system.

(Example 2) First, a barium titanate-based material composition shown in Table 5 as a ceramic material powder was prepared by a wet synthesis method. That is, BaCl ₂ , SrCl ₂ , CaCl ₂ , MgCl _2, and CeCl ₃ aqueous solutions are mixed, sodium carbonate (Na ₂ CO ₃ ) is added to adjust pH, and BaCO ₃ , SrCO ₃ , CaCO ₃ , MgCO ₃ , MgCO ₃ , Precipitated as Ce ₂ (CO ₃ ) ₃ . Mix each aqueous solution of TiCl ₄ and ZrOCl ₂ · 8H ₂ O, add 30% hydrogen peroxide water as a stabilizer, adjust the pH by adding caustic soda (NaOH), and precipitate containing Ti and Zr. I got a thing. Furthermore, the slurry of each deposit was fully mixed and the slurry which performed washing | cleaning dehydration was dried at 110 degreeC, and the dry raw material was obtained. Thereafter, the dried raw material was calcined at 700 ° C. and 1100 ° C. to prepare raw material powders having average particle sizes of 100 nm and 400 nm shown in Table 6.

  Next, ceramic green sheets having a thickness of 4.2 μm and 1.4 μm were prepared in the same manner as in Example 1. In addition, each thickness of 4.2 micrometers and 1.4 micrometers in a ceramic green sheet is corresponded to each thickness of 3 micrometers and 1 micrometer in a ceramic layer after passing through a baking process.

  Thereafter, a Ni paste was prepared in the same manner as in Example 1, and conductive pastes having thicknesses of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm were formed on the obtained ceramic green sheet. A film was formed. The thicknesses of the conductive paste films of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm are 0.8 μm, 0.7 μm, 0 in the internal electrode after the baking process, respectively. Corresponding to thicknesses of 4 μm, 0.2 μm and 0.1 μm.

  Thereafter, in the same manner as in Example 1, a multilayer ceramic capacitor was produced and evaluated. The results are shown in Table 7. In addition, what added * mark to the sample number of Table 7 is outside the scope of the present invention.

  In Table 7, the samples B1 and B8 marked with * have an internal electrode thickness of 0.8 μm, and delamination occurs at a high ratio. Similarly, samples B7 and B15 marked with * have an internal electrode thickness of 0.1 μm, and delamination occurs at a high ratio. In Sample B14 marked with *, the average grain diameter of the ceramic layer is 0.5 μm or less, the dielectric constant is low, and the reliability is poor.

On the other hand, in the samples B2 to B6 and B9 to B13 having an internal electrode thickness of 0.2 to 0.7 μm, delamination does not occur or hardly occurs.
In sample B2, the average particle size of the ceramic raw material powder exceeds 250 nm, and the reliability is somewhat poor in the above samples. In samples B6 and B9, the average particle diameter of the Ni powder exceeds 200 nm, and a decrease in coverage is observed. In Sample B13, the Ni powder particle size was less than 10 nm, and a decrease in coverage and slight delamination were observed.

  From the above results, also in Example 2, as in Example 1, when the thickness of the ceramic layer is 3 μm or less, the thickness of the internal electrode is 0.2 to 0.7 μm, and the average grain size of the ceramic grains is It can be seen that when the grain size exceeds 0.5 μm and the grain size of the ceramic grains in the thickness direction of the ceramic layer is equal to or less than the thickness of the ceramic layer, delamination is suppressed and the ceramic has excellent electrical characteristics.

  The ceramic grains constituting the ceramic layer of the multilayer ceramic capacitor were observed and analyzed with a transmission analytical electron microscope. Further, the ceramic constituting the ceramic layer was pulverized and subjected to powder X-ray diffraction analysis. The obtained diffraction pattern was subjected to Rietveld analysis to identify the crystal phase. As a result, it was confirmed that each ceramic grain had a uniform composition and crystal system, and consisted of one kind of ceramic grain having the same composition and crystal system.

(Example 3) First, the (Ca, Sr) (Ti, Zr) O ₃ -based material composition shown in Table 8 as a ceramic material powder was prepared by a solid phase method.
That is, CaCO ₃ , SrCO ₃ , TiO ₂ , ZrO ₂ and MnO ₂ were prepared, wet mixed and pulverized with a ball mill using zirconia cobblestone, and then dried to obtain a dry raw material.
Thereafter, the dried raw material was calcined at 1000 ° C. and 1200 ° C. to prepare raw material powders having average particle diameters shown in Table 9 of 150 nm and 500 nm.

   Next, ceramic green sheets having a thickness of 4.2 μm and 1.4 μm were prepared in the same manner as in Example 1. In addition, each thickness of 4.2 micrometers and 1.4 micrometers in a ceramic green sheet is corresponded to each thickness of 3 micrometers and 1 micrometer in a ceramic layer after passing through a baking process.

  Thereafter, a Ni paste was prepared in the same manner as in Example 1, and conductive pastes having thicknesses of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm were formed on the obtained ceramic green sheet. A film was formed. The thicknesses of the conductive paste films of 1.2 μm, 1.0 μm, 0.6 μm, 0.3 μm, and 0.15 μm are 0.8 μm, 0.7 μm, 0 in the internal electrode after the baking process, respectively. Corresponding to thicknesses of 4 μm, 0.2 μm and 0.1 μm.

  Thereafter, in the same manner as in Example 1, a multilayer ceramic capacitor was produced and evaluated. The results are shown in Table 10. In addition, what added * mark to the sample number of Table 10 is a thing outside the scope of the present invention.

  In Table 10, in Samples C1 and C9 marked with *, the thickness of the internal electrode is 0.8 μm, and delamination occurs at a high ratio. Similarly, samples C8 and C13 marked with * have an internal electrode thickness of 0.1 μm, and delamination occurs at a high ratio. In the sample C2 marked with *, the average grain diameter of the ceramic layer is 0.5 μm or less, the dielectric constant and the Q value are low, and the reliability is poor.

  On the other hand, delamination did not occur in samples C3 to C7 and C10 to C12 having internal electrode thicknesses of 0.2 to 0.7 μm. However, in sample C3, the average particle size of the ceramic raw material powder exceeds 250 nm, and the reliability is somewhat poor in the above samples.

  From the above results, also in Example 3, as in Example 1, when the thickness of the ceramic layer is 3 μm or less, the thickness of the internal electrode is 0.2 to 0.7 μm, and the average grain size of the ceramic grains Is larger than 0.5 μm and the grain size of the ceramic grains in the thickness direction of the ceramic layer is equal to or less than the thickness of the ceramic layer, it is understood that delamination is suppressed and the ceramic has excellent electrical characteristics.

  The ceramic grains constituting the ceramic layer of the multilayer ceramic capacitor were observed and analyzed with a transmission analytical electron microscope. Further, the ceramic constituting the ceramic layer was pulverized and subjected to powder X-ray diffraction analysis. The obtained diffraction pattern was subjected to Rietveld analysis to identify the crystal phase. As a result, it was confirmed that each ceramic grain was composed of two or more kinds of ceramic grains having a uniform composition and crystal system and different compositions.

1 is a cross-sectional view illustrating a multilayer ceramic capacitor according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Ceramic layer 3 Laminated body 4, 5 End surface 6, 7 External electrode 8, 9 Internal electrode 10, 11, 12, 13 Plating layer

Claims (7)

A step of preparing a ceramic slurry by mixing ceramic raw material powder, an organic binder and a solvent, a step of forming the ceramic slurry to obtain a ceramic green sheet, and a conductive paste containing a conductive metal powder in the ceramic green sheet A step of forming a film, a step of laminating the ceramic green sheet and the ceramic green sheet on which the conductive paste film is formed, and pressing to obtain a raw laminate, and the raw laminate in an N ₂ atmosphere A plurality of laminated ceramic layers, and a metal powder positioned between the ceramic layers and sintered by providing a step of heating and debinding in the step and a step of firing the debonded laminate. In a method for producing a multilayer ceramic electronic component, wherein a laminate including the obtained internal electrode is obtained
The ceramic raw material powder has an average particle size of 25 to 250 nm,
The conductive metal powder has an average particle size of 10 to 200 nm,
The ceramic layer has a thickness of 3 μm or less;
The internal electrode layer has a thickness of 0.2 to 0.7 μm,
The method for producing a multilayer ceramic electronic component, wherein an average grain size of ceramic grains constituting the ceramic layer exceeds 0.5 μm.   It further comprises external electrodes formed on the opposing end faces of the laminate, the ceramic layer is made of a ceramic dielectric, and the plurality of internal electrodes are electrically connected to any one of the external electrodes 2. The method of manufacturing a multilayer ceramic electronic component according to claim 1, wherein each end edge is formed in a state of being exposed to the end face, thereby forming a multilayer ceramic capacitor. 3. .   The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the metal powder is made of a base metal.   The method for manufacturing a multilayer ceramic electronic component according to claim 3, wherein the base metal is a metal containing nickel.   5. The multilayer ceramic electronic component according to claim 1, wherein the internal electrode is formed through a process in which a paste containing the metal powder is applied by a printing method. 6. Method.   The ceramic grains constituting the ceramic layer are composed of one kind of ceramic grains having a uniform composition and crystal system in each ceramic grain and having the same composition and crystal system. A method for producing a multilayer ceramic electronic component according to any one of 1 to 5.   6. The ceramic grains constituting the ceramic layer are composed of two or more kinds of ceramic grains having a uniform composition and a crystal system in each ceramic grain and having different compositions. The manufacturing method of the multilayer ceramic electronic component in any one of.