TWI421882B - Barium titanate powder, nickel paste, preparation method and laminated ceramic capacitors - Google Patents

Description

Barium titanate powder, nickel paste, manufacturing method and laminated ceramic capacitor

The present invention relates to a barium titanate powder used for forming a laminated ceramic capacitor, a nickel paste containing the powder, a method for producing the same, and a multilayer ceramic capacitor.

In the conventional internal electrodes of laminated ceramic capacitors (hereinafter also referred to as MLCC), Pd powder is used. In recent years, in order to reduce costs, nickel powder has been used in the above electrodes. Patent Document 1 discloses a nickel powder for forming a material of an internal electrode of an MLCC. A general manufacturing method of an MLCC internal electrode using nickel powder is as follows.

The nickel powder, the binder, and the solvent are mixed, and a nickel paste in which the nickel powder and the dielectric ceramic powder are dispersed in the vehicle liquid is used as an internal electrode material, and is applied to a ceramic green sheet of dielectric ceramic by screen printing or the like. Next, the multilayered layered body of the ceramic green sheets is multilayered by a lamination step, and is heated and pressed to be integrated. Then, the binder is treated at 500 ° C or lower in an oxidizing atmosphere or an inert atmosphere, cut into a predetermined size, and then fired in a reducing atmosphere to produce MLCC.

In order to promote miniaturization, multilayering, and large capacity of MLCC, thinning of internal electrodes has become an important technology. Therefore, when a small-sized and large-capacity MLCC is produced using a nickel paste, it is preferable to use a nickel powder which is a low-resistance electrode material when cracking or peeling occurs at a very small coating amount.

Thin film formation of the MLCC electrode, as disclosed in Patent Document 1, is important in that the size of the nickel powder particles for forming the internal electrode and the particle shape thereof are spherical. In the manufacturing step of the MLCC, the spherical fine particles increase the packing density in the electrode paste film, and the formation of the thin film electrode can be facilitated, and the effect of not causing cracks or peeling can be achieved. In particular, Patent Document 1 discloses that nickel fine particles are spherical and are affected by the content ratio of sulfur contained in the paste.

Usually, the nickel powder contains only a very small amount of sulfur (impurities). When the internal electrode is formed by using a nickel paste of a general nickel powder, in the debonding step, the thermal decomposition of the binder is induced by the catalytic action on the surface of the nickel particles to generate a binder component gas. At this time, the thermal decomposition of the binder is concentrated near the surface of the nickel particles, because the other binders are hardly decomposed, so that the gas generated by this partial decomposition is shut inside, so that the ceramic dielectric layer and the nickel internal electrode layer are The expansion occurred, causing structural defects.

On the other hand, Patent Documents 2, 3, and 4 disclose that the nickel paste containing a sulfur component can achieve the effect of sintering retardation in the MLCC manufacturing step, and contributes to suppressing the occurrence of the above structural defects.

Patent Document 1: Japanese Laid-Open Patent Publication No. 11-80817

Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-24539

Patent Document 3: Japanese Laid-Open Patent Publication No. 2004-244654

Patent Document 4: Japanese Laid-Open Patent Publication No. 2008-223068

The sulfur-added nickel paste disclosed in Patent Documents 2 to 4 is verified below.

First, in Patent Document 2, a nickel powder is dispersed in a vehicle liquid (a binder is dissolved in a solvent), and a sulfur-containing organic compound containing a triazine thiol-based compound or a sulfate-containing compound is mixed. For example, a sulfate-containing compound is an aliphatic or aromatic hydrocarbon containing sulfate SO ₃ or a salt thereof, specifically sodium lauryl sulfate CH ₃ (CH ₂ ) ₁₁ SO ₃ Na, laurylbenzenesulfonic acid Sodium C ₁₂ H ₂₅ C ₆ H ₄ SO ₃ Na, and the like. Therefore, even if the sulfur content is only a small amount, excessive organic components are mixed into the nickel paste, and in particular, benzene or the like is an environmentally-charged substance, which has a great influence on human health or the environment, and even if it is decomposed by firing, after firing, It also exists in the form of residual carbon. In addition, Na also has an adverse effect on the electrical properties of MLCC in the form of impurities.

Patent Document 3 uses a sulfur-coated nickel particle which is a surface of a nickel powder coated with sulfur or a sulfuric acid group by contacting a nickel powder with a gas containing a specific amount of sulfur. Although the nickel powder itself is generally produced by a chemical vapor phase reaction method or a wet method, according to the sulfur-coated nickel particle method of Patent Document 3, an additional sulfur coating treatment is required in the nickel powder production step. Therefore, in the case of Patent Document 3, there is a problem in that, in order to perform the sulfur coating treatment, the nickel powder production step is changed, the manufacturing apparatus is complicated, and it is difficult to produce a low-cost Ni powder on a mass production scale, and In consideration of the effect on the human health caused by the use of hydrogen sulfide in the sulfur coating treatment step, there is a problem in the workability and safety of the device. Further, in the sulfur coating treatment step, the nickel particles are bonded to each other and then agglomerated to form a nickel paste, which may adversely affect the electrode formation of the film.

In the method of Patent Document 4, when nickel powder is produced, hydrogen sulfide gas is introduced into a reaction apparatus to produce sulfur-containing sulfur-containing nickel powder. Further, in order to prevent the sulfur atom contained therein from being oxidized and desorbed, for example, a surface oxidation treatment is carried out in which the surface is instantly oxidized by rapidly cooling the nickel particles in contact with an oxidizing gas at a high temperature in a gas phase. . However, in Patent Document 4, in consideration of the influence of the use of hydrogen sulfide as a reaction gas on human health, in addition to problems in the workability or safety of the device, the surface oxidation treatment method of nickel particles is transmitted through When the cooling tube is connected to the outlet side of the reaction tube to cool the nickel powder, the surface is oxidized by feeding a large amount of air. Therefore, it is difficult to control the degree of oxidation of the nickel particles, and the inside is oxidized, and the counter electrode is formed. The electrical characteristics of the MLCC cause adverse effects.

In view of the above problems, it is an object of the present invention to provide a sulfur-containing barium titanate for use in a nickel paste for forming a multilayer ceramic capacitor, which can suppress sintering in a production stage of a multilayer ceramic capacitor. The occurrence of cracks, etc., improves the yield of capacitor manufacturing. Moreover, another object of the present invention is to provide a nickel paste containing the sulfur-containing barium titanate which can form an internal electrode with high quality while suppressing the occurrence of cracks or the like during firing in the production stage of the multilayer ceramic capacitor, and the manufacture thereof. The method, and an object of the present invention, is to provide a laminated ceramic capacitor formed using a nickel paste containing sulfur-containing barium titanate and having internal electrodes free from cracks and the like.

A first aspect of the present invention is a nickel paste used for an internal electrode of a multilayer ceramic capacitor, comprising nickel powder, a binder, a solvent, and sulfur-containing barium titanate mixed with sulfur in a barium titanate powder.

According to a second aspect of the present invention, in the first aspect, the barium titanate powder contains 1 to 30% by weight based on the nickel powder, and the sulfur contains 0.01 to 1 with respect to the barium titanate powder. weight%.

According to a third aspect of the present invention, in the first or second aspect, the lattice constant ratio (r/axis ratio: c/a ratio) of the sulfur-containing barium titanate powder is The range of 1.0040 to 1.0100.

According to a fourth aspect of the present invention, in the first, second or third aspect, the composition ratio of Ba (Ti) to Ti (Ti) of the sulfur-containing barium titanate powder (Ba/Ti) ) is 0.99 to 1.01.

According to a fifth aspect of the invention, the sulphur-containing barium titanate powder has an average particle diameter of 10 to 100 nm or less and is tetragonal or higher. Crystalline spherical sulfur-containing barium titanate powder.

A sulphur-containing barium titanate powder which is added to the nickel paste of any one of the first to fifth aspects, which contains sulfur, has an average particle diameter of 10 to 100 nm or less, and is tetragonal, It has a highly crystalline spherical shape.

According to a seventh aspect of the present invention, in a method for producing a nickel paste, a medium containing a binder and a solvent is mixed with nickel powder and sulphur-containing barium titanate mixed with sulfur barium titanate powder to produce A nickel paste is formed for the internal electrodes of the multilayer ceramic capacitor.

According to an eighth aspect of the present invention, in the multilayer ceramic capacitor, the nickel paste of any one of the first to fifth embodiments is applied to a ceramic substrate and fired to form an internal electrode using nickel as a conductive element.

In the case of the nickel paste used for the internal electrodes of the MLCC, the inventors of the present invention have many problems in the sulfur addition method in which sulfur is directly supported on the nickel powder as in Patent Documents 3 and 4, and the following findings are obtained: The barium titanate material having the effect of suppressing the sintering of the electrode paste can further exhibit the sintering delay effect by mixing the sulfur-containing barium titanate into the vehicle. According to the first aspect of the present invention, the present invention is excellent in that it contains nickel powder, a binder, a solvent, and sulfur-containing sulfur-containing barium titanate mixed with barium titanate powder. The sintering delay effect can sufficiently suppress the occurrence of cracks or the like during firing in the production stage of the multilayer ceramic capacitor. That is, by the sintering delay effect of the sulfur-containing barium titanate which further enhances the sintering delay effect by containing sulfur, the binder component on the surface of the nickel particles in the paste is thermally decomposed and the accompanying gas in the manufacturing step of the MLCC. Since it is extremely intensely suppressed, it is possible to prevent occurrence of structural defects such as cracks or layer peeling during the firing stage. Therefore, by using the nickel paste of the present embodiment, the manufacturing yield of the laminated ceramic capacitor can be improved, and the MLCC having a high quality internal electrode can be obtained.

Further, according to the dielectric property verification test of the two kinds of nickel pastes having different nickel contents by the present inventors (see Examples 2 and 3 described later), the case of using a nickel paste containing sulfur-containing barium titanate powder, Compared with the case where no sulfur is contained, the electrostatic capacitance value is high, and it is known that the nickel paste using the sulfur-containing barium titanate powder can increase the capacity of the MLCC. Therefore, since the nickel paste using the sulfur-containing barium titanate powder has an effect of increasing the electrostatic capacitance, it is possible to reduce the nickel content when the capacitance is limited, which contributes to the thinning and low MLCC. Price.

In particular, in the present embodiment, since sulfur is not directly supported on the nickel powder, but sulfur-containing sulfur-containing barium titanate is additionally used in the barium titanate powder, the nickel powder is used in comparison with the case of Patent Document 3. At the manufacturing stage, hydrogen sulfide gas is not used as the reaction gas, which does not affect the health of the human body, ensures good workability or safety, and does not induce nickel particles as compared with the case of Patent Document 4. The oxidation of the nickel particles accompanying the surface oxidation treatment can form a high quality internal electrode. The sulfur supporting form is not particularly limited, and may be contained in the form of sulfate or may be coated on the tantalum powder particles in addition to the sulfur powder mixed in the barium titanate powder. In particular, when it is contained in the form of a sulfate group, it is preferably in the case of Patent Document 2, and a sulfate-containing compound such as sodium lauryl sulfate or sodium laurylbenzenesulfonate is not used, but an organic component such as benzene or the like is not left. In the form of an impurity element such as Na, the synthesis of sulfate is carried out on barium titanate.

The nickel powder of the present invention can be obtained by using nickel hydride powder (by CVD (Chemical Vapor Growth) method, PVD (Physical Vapor Growth) method, spray pyrolysis method and wet chemical reduction method, or wet chemistry It is produced by a heat treatment in a reducing atmosphere to obtain a method for producing nickel powder, an atomization method, or the like. The powder form of the nickel powder is preferably an average particle diameter of 10 nm to 1 μm, and is not limited to the particle form, and a flake powder may also be used. In addition to the nickel monomer powder obtained by the above various production methods, the nickel powder includes, for example, a nickel alloy material to which chromium, phosphorus, zinc, a noble metal, a rare earth metal or the like which imparts oxidation resistance to nickel is added.

Further, the nickel powder may not contain the impurity sulfur generated in the production stage, and if it is contained in a small amount, the effect of suppressing the intense combustion of the resin component can be achieved.

The solvent of the present invention may, for example, be an alcohol, acetone, propanol, ethyl acetate, butyl acetate, ether, petroleum ether, mineral spirits, other paraffinic hydrocarbon solvent, or butyl carbitol, terpineol or Dihydroterpineol, butyl carbitol acetate, dihydroterpineol acetate, dihydrocarvyl acetate, celery acetate, acetic acid Acetate or other esters such as terpinyl acetate or benzoic acid ester, propionic acid solvent such as dihydrogen rosinate propionate, dihydrocarvyl propionate or isodecyl propionate, ethyl cellosolve Or solvents such as butyl cellosolve, such as sulphide, aromatics, diethyl phthalate, and other electrode pastes can be used.

The binder of the present invention is preferably a resin binder such as ethyl cellulose, polyvinyl acetal, acrylic resin, alkyd resin or the like, and resins used for other electrode coatings are included.

According to a second aspect of the present invention, the barium titanate powder is contained in an amount of 1 to 30% by weight based on the nickel powder, and the sulfur is contained in an amount of 0.01 to 1% by weight based on the barium titanate powder. Therefore, the electrode paste can be sufficiently sintered. The retardation effect enables a small, large-capacity MLCC with high-quality internal electrodes with a very small amount of electrode coating.

The sulfur-containing barium titanate powder contained in the nickel paste of the present invention can be used by using a barium titanate material having a usual crystallinity, and sulfur can be used. Particularly, it is preferable to use a titanic acid having high crystallinity.钡 material. In other words, according to the third aspect of the present invention, since the crystallized sulphur-containing barium titanate powder having a lattice constant ratio (r/axis ratio: c/a ratio) of 1.040 to 1.0100 is added, it is possible to A nickel paste that fully exerts the sintering delay effect of the electrode paste.

According to the fourth aspect of the present invention, since the sulfur-containing barium titanate powder having a composition ratio (Ba/Ti) of cerium (Ba) to titanium (Ti) of 0.99 to 1.01 is added, sintering of the electrode paste can be sufficiently exhibited. Delayed effect of nickel paste.

According to the fifth aspect of the present invention, since the sulfur-containing barium titanate powder having an average particle diameter of 10 to 100 nm or less and having a tetragonal crystal and having a high crystal spherical shape is added, the sintering delay of the electrode paste can be sufficiently exhibited. The effect of nickel paste.

According to the sixth aspect of the present invention, it is possible to provide a sulfur-containing barium titanate which contains sulfur, has an average particle diameter of 10 to 100 nm or less, is tetragonal, has a highly crystalline spherical shape, and is suitable for forming a high-quality MLCC internal electrode. powder.

According to the seventh aspect of the present invention, since nickel powder and sulfur-containing barium titanate are mixed in the vehicle liquid to produce a nickel paste for internal electrode formation of MLCC, the sintering delay of the sulfur-containing barium titanate can be excellent. The effect is that defects such as cracks do not occur at the time of firing, and the manufacturing yield of the MLCC is improved, and a small-sized and large-capacity MLCC having a high-quality internal electrode can be manufactured simply and at low cost.

The nickel paste of any one of the first to sixth aspects is applied to a ceramic substrate and fired to form an internal electrode. Therefore, a multilayer ceramic capacitor which does not contain defects such as cracks during firing can be realized.

Hereinafter, the sulfur-containing barium titanate of the embodiment of the present invention will be described.

Measuring the various physical properties of sulphur-containing strontium titanate powder added with barium titanate (BaTiO ₃ ) and titanate paste added with the sulphur-containing barium titanate, and testing the effectiveness of the paste material (heat resistance and shrinkage) Inhibitory). A sulphur-containing barium titanate sample containing 0.1% by weight of sulphur relative to barium titanate powder (BT2) was prepared using 100 nm-sized barium titanate powder. For comparison, a sulfur-free barium titanate sample (BT1) having the same particle diameter of 100 nm was produced.

Fig. 1 is a SEM (Scanning Electron Microscope) photograph showing BT1. (1A) of Fig. 1 shows the same figure (1B) magnified 10/3 times. Figure 2 shows an SEM photograph of BT2. (2A) of Fig. 2 shows the same figure (2B) magnified 10/3 times. The sulfur-free barium titanate BT1 and the sulfur-containing barium titanate BT2 each have a specific surface area of 13.9 m ² /g, and the primary particle diameter is the same, and there is no difference in sintering delay effect depending on the particle size.

3 is a particle size distribution diagram of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2, and the particle size distributions of BT1 and BT2 are shown in the same figures (3A) and (3B), respectively. The horizontal axis and the vertical axis show the particle diameter (μm) and the volume frequency (%), respectively. Fig. 4 shows the number distribution and volume distribution data of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2, respectively. The particle size distribution uses a commercially available particle size distribution measuring machine. Among the number distribution data, ave. indicates the average particle diameter (μm), and the CV value is expressed by the following formula.

CV value = ((standard deviation σ) / (arithmetic diameter)) × 100

Further, a soft body having a particle size distribution calculated based on the volume reference distribution was used, and the following volume distribution value (SPAN) was obtained.

SPAN=(D90-D10)/D50

Wherein, the particle size distribution, D10 means that the ratio of the particles below this value is 10% of the particle diameter (μm), D50 means that 50% of the particles are larger than this value, and 50% is smaller than this value (μm), D90 The ratio of the particles below this value is 90% of the particle diameter (μm). From the results of the particle size distribution, it was not confirmed whether the sulfur content affected the aggregation of the barium titanate powder, and when it contained sulfur, it was dispersible even when compared with the barium titanate containing no sulfur (having a uniform particle size without coarse particles). Distribution) Very excellent barium titanate powder.

Fig. 5 shows the results of TMA (thermomechanical measuring device) measurement of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2. The TMA measurement was carried out in nitrogen containing 2% H ₂ . The horizontal axis and the vertical axis of Fig. 5 indicate temperature (°C) and length change rate (%), respectively. From the measurement results of TMA, it is understood that if sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2 are compared, sulfur-containing barium titanate BT2 is superior in sintering delay effect to sulfur-free BT1.

Fig. 6 is a graph showing X-ray diffraction results of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2. The X-ray diffraction patterns and peaks of the samples BT1 and BT2 are shown in the same figures (6A) and (6B), respectively.

7 is a graph showing surface roughness measurement results when the samples BT1 and BT2 (the samples obtained by gelatinizing the sulfur-free barium titanate BT1 and the sulfur-containing barium titanate BT2) are dried and dried by the MLCC model. (Ra, Rmax). In the gelatinization, the samples BT1 and BT2 were mixed with an ethyl cellulose powder, a dispersing agent for an electrode paste, and a vehicle liquid of terpineol, and subjected to dispersion treatment by a bead mill. In the case of BT1, Ra was 0.019 μm and Rmax was 0.445 μm. In the case of BT2, Ra was 0.015 μm and Rmax was 0.333 μm. The surface of the gelatinized sample is very smooth and has excellent dispersibility and is excellent, and is suitable for use on a thin film electrode.

As is clear from the measurement results of TMA of FIG. 5, the sulfur-containing barium titanate has excellent heat resistance, that is, a shrinkage suppressing effect, and can be used as a nickel paste material which contributes to good capacity characteristics of MLCC.

The following shows an example of a nickel paste containing sulfur-containing barium titanate and an MLCC using the nickel paste.

<Example 1>

The nickel paste composition is composed of the following components: 30% by weight of nickel powder having an average particle diameter of 0.2 μm, a sulfur-containing high-crystalline barium titanate powder having an average particle diameter of 100 nm, or only composed of a sulfur-free barium titanate ceramic. High crystalline barium titanate powder 6.0% by weight (20% by weight relative to nickel powder), resin solid content (ethyl cellulose powder) 7.0% by weight, electrode paste dispersant 0.5% by weight, solvent (terpineol solvent) ) 56.5 wt%. These components were dispersed and mixed by three ceramic rolls to prepare two kinds of (M11, sulfur-free M12) nickel paste. Further, the nickel pastes M11 and M12 were printed on a barium titanate ceramic sheet (thickness: about 4.0 μm) in the form of an electrode pattern, and 20 layers were laminated to obtain an MLCC sample. For the high-crystalline barium titanate powder, a barium titanate material having a lattice constant ratio (r-axis to a-axis ratio: c/a ratio) of 1.040 to 1.0100 is preferably used. Further, as the barium titanate powder, a barium titanate material having a composition ratio (Ba/Ti) of barium (Ba) to titanium (Ti) of 0.99 to 1.01 is preferably used.

Further, the inorganic content of each of the nickel pastes M11 and M12 was 36.0% and 35.9%, and the respective nickel contents were 30.0% and 29.9%.

Fig. 8 is a photograph showing a cross-sectional structure of an MLCC sample produced using nickel pastes M11 and M12. (8A) and (8B) of Fig. 8 show a photograph of the cross-sectional structure of the MLCC sample produced using the nickel paste M11, and (8A) shows (8B) which is magnified twice. (8C) and (8D) of Fig. 8 show a photograph of the cross-sectional structure of the MLCC sample prepared using the nickel paste M12, and (8C) shows a magnification of (8D) twice. The firing conditions of the MLCC sample were reoxidized at 1230 ° C for 2 hours in a nitrogen atmosphere containing 3% H ₂ , and then reoxidized at 1000 ° C for 3 hours in a nitrogen atmosphere.

Fig. 9 and Fig. 10 show measurement results of electrical characteristics of MLCC samples prepared using nickel pastes M11 and M12. (9A) and (9B) of Fig. 9 show the electrostatic capacitance and the insulation resistance value, respectively, and (10A) and (10B) of Fig. 10 respectively show the loss coefficient and the DC breakdown voltage value.

According to Example 1, regarding the electrostatic capacity of the MLCC, there is a significant difference in the case of having sulfur and sulfur. That is, in the case of using the nickel paste M12 of the sulfur-containing barium titanate powder, the electrostatic capacity is about 6% higher than that of the nickel paste M11 using the sulfur-free barium titanate powder. Therefore, by using a nickel paste having sulfur-containing barium titanate powder, the number of layers of the ceramic sheets can be reduced for a predetermined capacity value, and an inexpensive MLCC product can be provided by reducing the cost of raw materials. Further, when sulfur-containing barium titanate powder is used, it is possible to realize a MLCC having a small structural defect and a small size and a large capacity.

In Example 1, the MLCC samples of the nickel pastes M11 and M12 were used, and the amount of nickel adhesion per unit area (mg/cm ² ) was 0.61 and 0.62, respectively. The nickel adhesion amount is determined based on the weight value after firing and considering the nickel content. Therefore, although the nickel adhesion amount does not change in any of the nickel pastes, the continuity of the electrodes is excellent in the case of using a nickel paste containing sulfur-containing barium titanate powder, and thus it is also known to use a sulfuric acid-containing titanic acid. The MLCC of the powdered nickel paste has better capacity characteristics.

Next, Examples 2 and 3 of the inorganic content and the nickel content of the adjusted nickel paste will be described.

<Example 2>

The nickel paste composition is composed of the following components: 35.0% by weight of nickel powder having an average particle diameter of 0.2 μm, a sulfur-containing high-crystalline barium titanate powder having an average particle diameter of 100 nm, or a ceramic containing only sulfur-free barium titanate. High crystalline barium titanate powder 7.0% by weight (20% by weight relative to nickel powder), resin solid content (ethyl cellulose powder) 5.3% by weight, electrode paste dispersant 0.5% by weight, solvent (terpineol solvent) 52.2% by weight. These components were dispersed and mixed by three ceramic rolls to prepare two kinds of (M22, sulfur-free M22) nickel paste. Further, the nickel pastes M21 and M22 were printed on a barium titanate ceramic sheet (thickness: about 4.0 μm) in the form of an electrode pattern, and 10 layers were laminated to obtain an MLCC sample. For the high-crystalline barium titanate powder, a barium titanate material having a lattice constant ratio (r-axis to a-axis ratio: c/a ratio) of 1.040 to 1.0100 is preferably used. Further, as the barium titanate powder, a barium titanate material having a composition ratio (Ba/Ti) of barium (Ba) to titanium (Ti) of 0.99 to 1.01 is preferably used. Further, the inorganic content of each of the nickel pastes M21 and M22 was 42.12% and 42.10%, and the respective nickel contents were 35.13% and 35.08%.

Fig. 11 is a photograph showing a cross-sectional structure of an MLCC sample produced using nickel pastes M21 and M22. (11A) and (11B) of Fig. 11 show a photograph of the cross-sectional structure of the MLCC sample produced using the nickel paste M21, and (11A) shows (11B) which is magnified twice. (11C) and (11D) of Fig. 11 show a photograph of the cross-sectional structure of the MLCC sample produced using the nickel paste M22, and (11C) shows a magnification of (11D) twice. The firing conditions of the MLCC samples using the nickel pastes M21 and M22 were the same as those of the nickel pastes M11 and M12.

Fig. 12 is a graph showing measurement results of electrical characteristics of MLCC samples prepared using nickel pastes M21 and M22. (12A), (12B), (12C), and (12D) of Fig. 12 indicate electrostatic capacitance, insulation resistance value, loss coefficient, and DC breakdown voltage value, respectively.

<Example 3>

The nickel paste composition is composed of the following components: a zinc powder having an average particle diameter of 0.2 μm, 37.5% by weight, a sulfur-containing high-crystalline barium titanate powder having an average particle diameter of 100 nm, or a ceramic containing only sulfur-free barium titanate. High crystalline barium titanate powder 7.5% by weight (20% by weight relative to nickel powder), resin solid content (ethyl cellulose powder) 4.3% by weight, electrode paste dispersant 0.5% by weight, solvent (terpineol solvent) 50.2% by weight. These components were dispersed and mixed by three ceramic rolls to prepare two kinds of (M1, sulfur-free M32) nickel paste. Further, the nickel pastes M31 and M32 were printed on a barium titanate ceramic sheet (thickness: about 4.0 μm) in the form of an electrode pattern, and 10 layers were laminated to obtain an MLCC sample. For the high-crystalline barium titanate powder, a barium titanate material having a lattice constant ratio (r-axis to a-axis ratio: c/a ratio) of 1.040 to 1.0100 is preferably used. Further, as the barium titanate powder, a barium titanate material having a composition ratio (Ba/Ti) of barium (Ba) to titanium (Ti) of 0.99 to 1.01 is preferably used. Further, the inorganic content of each of the nickel pastes M31 and M32 was 45.09% and 45.00%, and the respective nickel contents were 37.58% and 37.50%.

Fig. 13 is a SEM photograph showing an MLCC sample prepared using nickel pastes M31 and M32. (13A) and (13B) of Fig. 13 show a photograph of the cross-sectional structure of the MLCC sample produced using the nickel paste M31, and (13A) shows (13B) which is magnified twice. (13C) and (13D) of Fig. 13 show a photograph of the cross-sectional structure of the MLCC sample prepared using the nickel paste M32, and (13C) shows a magnification of (13D) twice. The firing conditions of the MLCC samples using the nickel pastes M31 and M32 were the same as those of the nickel pastes M11 and M12.

Fig. 14 is a graph showing measurement results of electrical characteristics of MLCC samples prepared using nickel pastes M31 and M32. (14A), (14B), (14C), and (14D) of Fig. 14 respectively indicate electrostatic capacitance, insulation resistance value, loss coefficient, and DC breakdown voltage value.

In Example 2 and Example 3, the MLCC samples of the nickel pastes M21, M22, M31 and M32 were used, and the nickel adhesion amount per unit area (mg/cm ² ) was 0.546, 0.540, 0.596, and 0.583, respectively. The nickel adhesion amount is determined based on the weight value after printing and considering the nickel content. Corresponding to the difference in the Ni content of the nickel powder (35.0% by weight, 37.5% by weight), the nickel paste (M31, M32) having a large Ni content, and the nickel adhesion amount are more than those of the nickel paste (M21, M22). . Therefore, regardless of the presence or absence of sulfur in the barium titanate powder, the nickel adhesion rate can be controlled by the nickel content.

For the two kinds of nickel pastes with different nickel contents, in the case of the presence or absence of sulfur, the case of using the sulfur paste of the barium titanate powder (M22, M32), and the case of not containing sulfur (M21, M31) Compared with the high electrostatic capacity, it is known that the use of sulfur-containing nickel strontium titanate paste contributes to the increase in capacity of the MLCC. Therefore, in the case of using the nickel paste of the sulfur-containing barium titanate powder (M22, M32), the structural defects can be greatly reduced by the sintering delay effect, and the static electricity is compared with the case of the sulfur-free case (M21, M31). Since the capacity is increased, the nickel content can be reduced when the limit capacitance is achieved, and the use of sulfur-containing barium titanate powder is more effective in the high quality, thinning, and lowering of MLCC.

[Table 1]

In all of the nickel pastes used in Examples 1 to 3, the average particle diameter of the nickel powder was 0.2 μm, and the average particle diameter of the barium titanate powder was 100 nm. As shown in Table 1, in Examples 4 and 5, the use was carried out. When the average particle diameter of the nickel powder and the barium titanate powder is small, a nickel paste is produced. In addition, Table 1 shows the mixing ratio (% by weight) and the average particle diameter (nm) of the barium titanate powder and the nickel powder used for producing each paste. Further, the table indicates whether or not the barium titanate powder contains sulfur.

<Example 4>

In Example 4, the nickel paste contained 36.5 wt% of nickel powder having an average particle diameter of 150 nm, a sulfur-containing high-crystalline barium titanate powder having an average particle diameter of 20 nm, or a high crystal consisting only of sulfur-free barium titanate ceramics. Barium titanate powder 4.0% by weight (about 10% by weight relative to nickel powder), 3.0% by weight of resin solid content (ethylcellulose powder), 1.0% by weight of dispersant for electrode paste, and solvent (terpineol solvent) 55.5 weight%. These components were dispersed and mixed by three ceramic rolls to prepare two kinds of (M46 containing no sulfur, M42 containing sulfur) nickel paste.

Further, the nickel pastes M41 and M42 were printed on a barium titanate ceramic sheet (thickness: about 4.0 μm) in the form of an electrode pattern, and 10 layers were laminated to obtain an MLCC sample. Further, Ni deposition amount of the electrode pattern is printed, using a nickel paste M41, M42 of the case, respectively, ^{0.300mg / cm 2, 0.307mg / cm} 2. Since the firing conditions are the same as those in the first embodiment, the description is omitted. In the measurement of the electrical characteristics of the MLCC samples prepared using the nickel pastes M41 and M42, it was confirmed that the respective electrostatic capacitances were about 570 nF and about 680 nF. That is, the electrostatic capacity can be increased by mixing the sulfur-containing high crystalline barium titanate powder in the nickel paste used for the production of the MLCC sample.

<Example 5>

In Example 5, the nickel paste contained 36.5 wt% of nickel powder having an average particle diameter of 120 nm, a sulfur-containing high-crystalline barium titanate powder having an average particle diameter of 20 nm, or a high crystal consisting only of sulfur-free barium titanate ceramics. Barium titanate powder 4.0% by weight (about 10% by weight relative to nickel powder), resin solid content (ethylcellulose powder) 5.3% by weight, electrode paste dispersant 1.5% by weight, solvent (terpineol solvent) 52.7 weight%. These components were dispersed and mixed by three ceramic rolls to prepare two kinds of (M51 containing no sulfur, M52 containing sulfur) nickel paste.

Further, nickel pastes M51 and M52 were printed on a barium titanate ceramic sheet (thickness: about 4.0 μm) in the form of an electrode pattern, and 10 layers were laminated to obtain an MLCC sample. In addition, in the case where the nickel pastes M51 and M52 were used, the Ni adhesion amount of the electrode pattern printing was 0.346 mg/cm ² and 0.343 mg/cm ² . In the measurement of the electrical characteristics of the MLCC sample using the nickel pastes M51 and M52, it was confirmed that the electrostatic capacitances were about 600 nF and about 730 nF, respectively. That is, as in the case of Example 4, the electrical characteristics of the MLCC sample can be improved by mixing the sulfur-containing high crystalline barium titanate powder in the nickel paste.

In addition, the average particle diameter of the nickel powder is preferably in the range of 10 nm to 1 μm, and when it is less than 10 nm, it is easily oxidized in the air due to ultrafine particles, and is unstable, and there is a risk of dust explosion or the like. Therefore, it is not suitable as a material for nickel paste. Moreover, when it exceeds 1 micrometer, it is difficult to thin the electrode of the MLCC manufactured using the nickel paste. Further, the content of the sulfur-containing high-crystalline barium titanate powder in the nickel paste is preferably in the range of 1 to 30% by weight based on the nickel powder, and when it is less than 1% by weight, the desired sintering inhibitor should not be obtained. If it is more than 30% by weight, it is an insulator, so that the conductivity of the nickel paste is greatly reduced, and it cannot be used for electronic parts such as MLCC.

The present invention is not limited to the above-described embodiments, and various modifications, design changes, and the like are of course included in the technical scope without departing from the scope of the invention.

Industrial availability

According to the present invention, by the nickel paste containing sulfur-containing barium titanate powder, the capacity of the MLCC can be increased, the film thickness or the miniaturization can be achieved with a very small amount of nickel adhesion, and the structural defects are extremely small, inexpensive, and small. Quality MLCC.

Figure 1 is a SEM (Scanning Electron Microscope) photograph of the sulfur-free barium titanate BT1 of the present invention.

Figure 2 is a SEM photograph of the sulfur-containing barium titanate BT2 of the present invention.

Fig. 3 is a particle size distribution diagram of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2.

Fig. 4 is a table showing the number distribution and volume distribution data of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2, respectively.

Fig. 5 is a graph showing the measurement results of TMA (thermomechanical measuring device) of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2.

Fig. 6 is a graph showing the results of X-ray diffraction of sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2.

Fig. 7 is a graph showing surface roughness measurement results (Ra, Rmax) of gelatinized sulfur-free barium titanate BT1 and sulfur-containing barium titanate BT2 after printing and drying by MLCC model.

Fig. 8 is a photograph showing the cross-sectional structure of an MLCC sample produced using nickel pastes M11 and M12.

Fig. 9 is a graph showing measurement results of electrostatic capacitance and insulation resistance value of an MLCC sample produced using nickel pastes M11 and M12.

Fig. 10 is a graph showing the measurement results of the loss coefficient and the DC breakdown voltage value of the MLCC sample produced using the nickel pastes M11 and M12.

Fig. 11 is a photograph showing the cross-sectional structure of an MLCC sample produced using nickel pastes M21 and M22.

Fig. 12 is a graph showing measurement results of various electrical characteristics of MLCC samples produced using nickel pastes M21 and M22.

Fig. 13 is a photograph showing the cross-sectional structure of an MLCC sample produced using nickel pastes M31 and M32.

Fig. 14 is a graph showing measurement results of various electrical characteristics of MLCC samples prepared using nickel pastes M32 and M33.

Claims (8)

A nickel paste for use in an internal electrode of a laminated ceramic capacitor, comprising: a nickel powder, a binder, a solvent, and a sulfur-containing barium titanate mixed with sulfur in a barium titanate powder; the barium titanate powder is relatively The nickel powder contains 1 to 30% by weight, and the sulfur is 0.01 to 1% by weight based on the barium titanate powder. The nickel paste of claim 1, wherein the ratio of lattice constant (ratio of c-axis to a-axis: c/a ratio) of the sulfur-containing barium titanate powder is in the range of 1.040 to 1.0100. The nickel paste of claim 1 or 2, wherein the sulfur-containing barium titanate powder has a composition ratio (Ba/Ti) of 0.99 to 1.01. The nickel paste according to any one of claims 1 to 2, which contains the sulphur-containing barium titanate powder having an average particle diameter of 10 to 100 nm and having a tetragonal crystal and having a highly crystalline spherical shape. The nickel paste according to any one of claims 3, which contains the sulfur-containing barium titanate powder having an average particle diameter of 10 to 100 nm and having a tetragonal crystal and having a highly crystalline spherical shape. A sulfur-containing barium titanate powder, which is a nickel paste according to any one of claims 1 to 5, which is characterized in that only barium titanate powder is added with sulfur and has an average particle size of 10 to 100 nm or less. It is a tetragonal crystal and has a highly crystalline spherical shape. A method for producing a nickel paste, which is characterized in that a vehicle solution in which a binder and a solvent are dissolved is mixed with nickel powder and titanic acid a sulphur-containing sulfur-containing barium titanate mixed with bismuth powder to produce a nickel paste for internal electrode formation of a multilayer ceramic capacitor; the barium titanate powder contains 1 to 30% by weight with respect to the nickel powder, and the sulfur is relative to the The barium titanate powder contains 0.01 to 1% by weight. A multilayer ceramic capacitor in which a nickel paste according to any one of claims 1 to 6 is applied to a ceramic substrate and fired to form an internal electrode using nickel as a conductive element.