JP2007214244A - Electrode ink and laminated ceramic capacitor using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated ceramic capacitor such as a chip capacitor inhibiting the generation of a structural defect in the case of baking, reducing the lowering of an electrostatic capacity value, having the excellent temperature stability of a capacity value, and having a superior reliability. <P>SOLUTION: Electrode ink is used for forming an internal electrode 2 for the laminated ceramic capacitor alternately laminating the internal electrode 2 and a dielectric layer 1. The electrode ink contains nickel grains 8 as at least a main component and a resin binder, and is composed of approximately the same grains having the same composition comprised in the dielectric layer 1 as nickel grains 8 of 100 pts. The electrode ink contains approximately the same grains 8B of 0.5 to 3.0 pts. having a mean grain size having a grain size at 1.5 to 3.0 times of the mean size of core grains and grains 8C of 3 to 15 pts. approximately the same as the dielectric layer 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode ink for forming an internal electrode mainly composed of nickel powder, and a multilayer ceramic capacitor using the same.

  Multilayer ceramic capacitors are widely used as electronic components with small size, large capacity, and high reliability. With the recent miniaturization and high performance of electronic devices, further miniaturization, large capacity, high There is an increasing demand for reliability.

  A multilayer ceramic capacitor is formed by printing a conductive ink serving as an internal electrode on a green sheet made of a predetermined dielectric ceramic composition, laminating a plurality of green sheets printed with the conductive ink, The internal electrode is integrally fired at the same time. In particular, in recent years, those using base metal powder for internal electrodes have become mainstream because they are inexpensive and of high quality.

  In addition, in order to use an inexpensive base metal (for example, nickel or copper) as a material for the internal electrode, it does not become a semiconductor even when fired at a low temperature in a neutral or reducing atmosphere, that is, it has excellent reduction resistance. It is necessary to develop a dielectric ceramic composition having a sufficient dielectric constant and excellent temperature characteristics after firing.

  However, in electronic parts such as multilayer ceramic capacitors that are a combination of these, internal defects are caused by the difference in shrinkage behavior during densification during sintering at the interface between the metal that is the electrode and the dielectric layer that is the ceramic. This is likely to cause a short-circuit rate deterioration.

  As a countermeasure for these, in general, an adjustment material called a co-material is added to the electrode side in order to bring the contraction behavior of the electrode layer, which is a metal, close to the dielectric layer having a high firing temperature.

  FIG. 3 is a microstructure model diagram of the composition particles constituting the dielectric layer and the internal electrode of a conventional multilayer ceramic capacitor, 11 is a dielectric layer composed of dielectric particles 11A, and 12 is an internal electrode layer. The internal electrode layer 12 contains nickel particles 18 and internal electrode-containing particles 18A (common material).

  As the common material, generally the same as the dielectric particles 11A forming the dielectric layer 11, or those obtained by appropriately pulverizing the particles and miniaturizing the particle diameter are used.

  However, the ratio of the material added to the electrode ink as a co-material is as large as about 20% with respect to the metal powder of the electrode, leading to a small capacity of the multilayer ceramic capacitor or a structural defect (void portion 2c in FIG. 3). In recent years, it is not a good idea to generate

  On the other hand, attempts have been made to suppress structural defects and sufficiently suppress capacity reduction even when the amount added is increased by using a fine powder having a particle size of 0.1 μm or less as a common material. .

For example, Patent Document 1 and Patent Document 2 are known as prior art document information relating to the invention of this application.
JP 2005-63707 A Japanese Patent No. 3146967

  Conventionally, various proposals have been made in the case where nickel powder, which is a base metal, is used as a material for the internal electrode and a composition substantially the same as the dielectric ceramic composition is added as a common material. As a result, the short-circuit rate deteriorates, the capacitance value decreases, the temperature characteristics deteriorate, and the like, and the electrical characteristics, reliability, process yield, and the like have not been satisfied comprehensively. Due to the progress of small-sized and large-capacity, the thickness per layer of the dielectric layer is required to be 1 μm or less, and there is a problem that DC bias characteristics and reliability cannot be sufficiently secured due to an increase in electric field strength applied between the electrodes. is there.

  Further, in Patent Document 1, a configuration in which 0.1 to 30 wt% of the same fine particles as the 0.3 μm dielectric layer is added as a common material added to the electrode ink is proposed. In such a combination, the sintered particle size of the dielectric layer to be used promotes abnormal grain growth, and the initial electrical characteristics such as temperature characteristics and dielectric constant are impaired, which is further required. Since the behavior derived from the composition such as a predetermined dielectric constant and temperature characteristics changes, there is a problem that it is difficult to match characteristics unless design changes are repeatedly performed.

  On the other hand, in Patent Document 2, a means for balancing predetermined electrical characteristics by blending a plurality of types of compositions with a dielectric layer has been studied. There was a big problem in securing the burden and stability.

  Therefore, an object of the present invention is an electrode that is excellent in reduction resistance during firing, can be manufactured at a process condition that is not significantly changed as compared to the conventional one, while being able to achieve both a high relationship between the capacitance change rate and the dielectric constant that are in a trade-off relationship It is to provide an ink and a multilayer ceramic capacitor.

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 of the present invention is an electrode ink for forming an internal electrode pattern composed of nickel powder and a resin binder, and the internal electrode pattern has a dielectric against 100 parts of nickel particles as a main component. 0.5 to 3.0 of substantially the same particles having the same composition contained in the body layer and having an average particle size of 1.5 to 3.0 times the average size of the core particles. Ink containing 3 to 15 parts of particles that are substantially the same as the dielectric layer and the dielectric layer, and by using these inks, the dielectric constant and the capacity temperature characteristics such as X7R and X8R characteristics are compatible at a high level. The effect and the effect that there is no structural defect etc. and it is excellent in reliability are obtained.

  The invention according to claim 2 of the present invention is a sheet for an internal electrode of a multilayer ceramic capacitor in which a plurality of internal electrodes and dielectric layers are alternately laminated, the internal electrode comprising a resin binder and a main component nickel The particle size is approximately the same particle of the same composition contained in the dielectric layer with respect to 100 parts of the nickel particle, and the average particle size is 1.5 to 3.0 times the average size of the core particle A sheet for internal electrodes patterned from 0.5 to 3.0 parts of substantially the same particles having 3 to 15 parts of particles that are substantially the same as the dielectric layer, and having an appropriate dielectric As a result, there can be obtained an effect of achieving a high balance between the rate and capacity temperature characteristics such as X7R and X8R characteristics, and an excellent effect of reliability without structural defects.

The invention according to claim 3 of the present invention comprises a dielectric layer made of a dielectric ceramic composition having a particle diameter of 0.25 μm or less and a BET value of 4.5 to 10 m ² / g, nickel powder and a resin binder. In the multilayer ceramic capacitor in which the internal electrodes are alternately stacked, the internal electrodes are substantially the same particles of the same composition contained in the dielectric layer with respect to 100 parts of the main component nickel particles, and the average particle size is the core. 0.5 to 3.0 parts of substantially the same particles having a particle size 1.5 to 3.0 times the average size of the particles, and 3 to 15 parts of particles that are substantially the same as the dielectric layer This is a multilayer ceramic capacitor, and by comprehensively defining the size, combination, and addition amount of dielectric particles that coexist with nickel metal in the internal electrode, the balance between the dielectric constant and temperature characteristics of the dielectric layer is increased. level It is possible to maintain, it can be realized and reliability at a high level that it is possible to eliminate structural defects or short ratio deterioration that occurs in the sintering process.

  In the multilayer ceramic capacitor of the present invention, the electrode ink according to the present invention and the internal electrode sheet are used for the internal electrode, so that it has excellent capacity-temperature characteristics, no decrease in capacitance, and insulation resistance ( IR) and dielectric breakdown voltage (BDV) variations are improved, and a multilayer component such as a multilayer ceramic capacitor having a minimal short-circuit rate can be manufactured.

  The electrode ink for internal electrodes of the present invention, the sheet for internal electrodes and the multilayer ceramic capacitor using the same are substantially the same particles of the same composition contained in the dielectric layer with respect to 100 parts of the main component nickel particles, And 0.5 to 3.0 parts of substantially the same particles having an average particle size of 1.5 to 3.0 times the average size of the core particles, and 3 to 3 of particles that are substantially the same as the dielectric layer Containing 15 parts suppresses structural defects that are likely to occur during firing, has no reduction in capacitance after firing, has excellent capacity-temperature characteristics, and achieves high reliability. It is.

  Hereinafter, the electrode ink, the sheet for internal electrodes, and the multilayer ceramic capacitor of the present invention will be described using an embodiment. FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

  In the present embodiment, the multilayer ceramic capacitor shown in FIG. 1 is exemplified as the multilayer ceramic capacitor, and the structure thereof will be described.

  FIG. 2 is a microstructure model diagram of a composition particle constituting the dielectric layer and internal electrodes of the multilayer ceramic capacitor in one embodiment of the present invention shown in FIG. 1, and FIG. 3 is a dielectric layer of the conventional multilayer ceramic capacitor. 2 is a microstructure model diagram of composition particles constituting the internal electrode.

  As shown in FIG. 1, a multilayer ceramic capacitor according to an embodiment of the present invention has a capacitor element body 3 having a configuration in which dielectric layers 1 and internal electrode layers 2 are alternately stacked. At both ends of the capacitor element body 3, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 2 arranged alternately in the capacitor element body 3. The shape of the capacitor element body 3 is not particularly limited, but is usually a rectangular parallelepiped shape. Also, there is no particular limitation on the dimensions, and it may be an appropriate dimension according to the application. Usually, (0.6 to 5.6 mm) × (0.3 to 5.0 mm) × (0.3 ˜1.9 mm).

  The internal electrode layer 2 is laminated so that each end face is alternately exposed on two opposing end faces of the capacitor element body 3. The pair of external electrodes 4 are formed at both ends of the capacitor element body 3 and connected to the exposed end surfaces of the alternately arranged internal electrode layers 2 to constitute a multilayer ceramic capacitor.

The dielectric layer 1 contains the dielectric ceramic composition according to the present invention. The dielectric ceramic composition in the present invention is mainly composed of barium titanate represented by BaTiO ₃ . At this time, the abundance ratio of Ba and Ti in the above formula is in an arbitrary range depending on the powder production method. In the present invention, for example, 1.000 ≦ Ba / Ti ≦ 1.005. It is preferable. As the Ba / Ti ratio increases, the reactivity of the composition becomes more sensitive to sintering, so it is desirable to select it in consideration of combinations with other additive components. In the case of the present invention, a rare earth metal oxide, a transition metal oxide, and a glass component to be added as subcomponents other than the main component BaTiO ₃ can be blended in a predetermined amount.

  In the present invention, by making the Ba / Ti ratio of the main component barium titanate A-rich, the sensitivity to sinterability is weakened, and the contribution is regulated by combining the amount of glass components composed of Ba and Si. This ensures an appropriate balance. The glass component mainly consumes the action of forming the grain boundary phase and part of the Ba component in the A-site substitution of the main component barium titanate, so that the densification can be appropriately balanced. In the case of the invention, the range of 0.5 to 5.0 mol in terms of Ba and Si oxides is preferable with respect to 100 mol of barium titanate as the main component, and in particular, 3.0 mol or less is easy to control. More preferred.

Thus, by controlling the combination of Mg and rare earth metal species, the ratio, and the total amount of rare earth metal species with respect to BaTiO _3, the structural model shown in FIG. 2 can be formed, and BaTiO ₃ in fine particles is fired. The amount of magnesium or magnesium oxide that suppresses abnormal grain growth that occurs at the time and segregates at the grain boundary portion existing between the adjacent main component crystal grains in the dielectric ceramic composition is reduced. As a result, the dielectric constant of the capacitor increases.

In the present invention, for example, Mg is preferably 0.2 mol or more, and more preferably 0.2 to 2.5 mol with respect to the BaTiO ₃ particles. By setting Mg in such a range, the temperature characteristic of the dielectric constant can be stabilized even if the dielectric constant of the dielectric ceramic composition is appropriately increased.

  In addition, when the solid solution amount of magnesium is excessively small, the dielectric loss (tan δ) tends to deteriorate, so the lower limit of the solid solution amount is 0.2 mol. On the other hand, if the amount of magnesium becomes excessive, the sinterability of the composition will be extremely deteriorated, so approximately 2.5 mol is desirable.

  The dielectric ceramic composition according to the present invention includes at least one selected from oxides such as V, Mo, Zn, Cd, Sn, Mn, and Al in addition to alkaline earth metals such as Mg and rare earth metals. These subcomponents may be further added, and an appropriate combination and amount can be selected.

  By adding such a subcomponent, low temperature firing is possible without deteriorating the dielectric characteristics of the main component, and reliability failure when the dielectric layer 1 is thinned can be reduced, resulting in a long life. It is also possible to make it easier.

  Note that various conditions such as the number and thickness of the dielectric layers 1 shown in FIG. 1 may be appropriately determined according to the purpose and application. The dielectric layer 1 is composed of grains and grain boundary phases, and the average grain diameter of the dielectric layer 1 is preferably 0.25 μm or less.

  FIG. 2 is a microstructure model diagram of the composition particles constituting the dielectric layer and the internal electrode of the multilayer ceramic capacitor in one embodiment of the present invention shown in FIG. 1, wherein 1 is a dielectric composed of dielectric particles 1A. The body layer 2 is an internal electrode. The internal electrode 2 includes nickel particles 8 as main components and internal electrode-added particles having an average particle size of 1.5 to 3.0 times the average size of the core particles. A and the internal electrode addition particle | grains B which are substantially the same as the dielectric material layer 1 are contained.

  The particle microstructure of the dielectric ceramic composition constituting the dielectric layer 1 shown in FIG. 2 is composed of barium titanate that points to the center of the particle, a shell layer that surrounds the periphery, and a grain boundary phase. Mg, rare earth metal A, and rare earth metal B are segregated in the shell layer portion.

  On the other hand, the grain boundary phase is usually composed of oxides of materials constituting dielectric materials or internal electrode materials, oxides of materials added separately, and oxides of materials mixed as impurities during the process. Usually, it is composed of glass or glass.

  The conductive material contained in the internal electrode layer 2 is not particularly limited, but a base metal can be used because the constituent material of the dielectric layer 1 has reduction resistance. As the base metal used as the conductive material, 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, Fe, and Mg, may be contained by about 0.1 wt% or less. The thickness of the internal electrode layer may be appropriately determined according to the application and the like, and is usually 5 μm or less, and is preferably about 0.3 to 1.3 μm in consideration of future thinning.

  In order to adjust the difference in sintering density between the dielectric layer 1 and the internal electrode layer 2, it is recommended that the internal electrode layer 2 be mixed with an approximate ceramic component in the dielectric layer 1, and the capacitance value of the final product. Can be added to adjust the amount of addition.

  In the present invention, nickel powder synthesized by a wet method is used as the base metal for the electrode, but other dry methods may be used.

  In the present invention, in order to adjust the difference in sintering densification between the dielectric layer 1 and the internal electrode layer 2, 100 parts of the main component nickel particles are composed of substantially the same particles having the same composition contained in the dielectric layer 1. 0.5 to 3.0 parts of substantially the same particles (internal electrode added particles A) having an average particle size of 1.5 to 3.0 times the average size of the core particles, and a dielectric layer It is desirable that 3 to 15 parts of particles (internal electrode added particles B) substantially the same as 1 are contained.

  In the multilayer ceramic capacitor, since the thickness design of both the dielectric layer and the electrode varies depending on the shape and dimension thereof, it is more preferable to adjust the thickness in accordance with the design of the dielectric layer. The electrode pattern only needs to use this electrode ink, and the formation means may be any method such as a printing method and a transfer method.

  The conductive material contained in the external electrode 4 is not particularly limited, but usually Cu, Cu alloy, Ni, Ni alloy or the like is used. Of course, Ag, an Ag—Pd alloy, or the like can also be used. In this embodiment, inexpensive Ni, Cu, and alloys thereof are used. The thickness of the external electrode may be appropriately determined according to the application and the like, but is usually preferably about 0.6 to 50 μm.

  In the multilayer ceramic capacitor of the present invention, a green chip is produced by a normal printing method or a sheet method using a paste or slurry, and after firing this, the external electrode is printed or transferred in the same manner as a conventional multilayer ceramic capacitor. It is manufactured by baking.

  In addition, as a compound which becomes an oxide by baking, carbonate, nitrate, oxalate, an organometallic compound, etc. are illustrated, for example. Of course, you may use together an oxide and the compound which becomes an oxide by baking. What is necessary is just to determine content of each compound in a dielectric ceramic composition raw material so that it may become a composition of the above-mentioned dielectric ceramic composition after baking. The particle size of the dielectric ceramic composition raw material powder is usually about 0.01 to 2 [mu] m in average before the coating.

  Next, the dielectric ceramic composition raw material is made into a paint to prepare a dielectric layer slurry. The dielectric layer slurry may be an organic paint obtained by kneading a dielectric ceramic composition material and an organic vehicle, or may be a water-based paint.

  The organic vehicle is obtained by dissolving a binder in an organic solvent, and the binder used in the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent used at this time is not particularly limited, and may be appropriately selected from organic solvents such as butyl acetate, acetone, and toluene in accordance with a method such as a printing method or a sheet method.

  The water-based paint is obtained by dissolving a water-soluble binder, a dispersant, etc. in water. The water-based binder is not particularly limited, and is appropriately selected from polyvinyl alcohol, cellulose, water-soluble acrylic resin, emulsion, and the like. do it.

  The ink for internal electrodes is prepared by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above or various oxides, organometallic compounds, resinates and the like that become the above-mentioned conductive materials after firing. The The external electrode paste is also prepared in the same manner as the internal electrode ink.

  The organic vehicle content of the ink and paste described above is not particularly limited, and may be a normal content, for example, about 1 to 5% by weight for the binder and about 0.6 to 60% by weight for the solvent. The ink and paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary.

  When using the printing method, the dielectric paste and the internal electrode ink are laminated and printed on a substrate such as polyethylene terephthalate, cut into a predetermined shape, and then peeled off from the substrate to obtain a green chip. On the other hand, when the sheet method is used, a green sheet is formed using a dielectric slurry, an internal electrode paste is printed thereon, and these are stacked to form a green chip.

  Next, the green chip is subjected to binder removal processing and firing.

  The binder removal treatment of the green chip may be performed under normal conditions, but in particular, when a base metal such as Ni or Ni alloy is used as the conductive material of the internal electrode layer, the temperature rising rate is 5 to 300 ° C. in an air atmosphere. / Hour, more preferably 10 to 100 ° C./hour, a holding temperature of 180 to 400 ° C., more preferably 200 to 350 ° C., and a temperature holding time of 0.5 to 24 hours, more preferably 1 to 20 hours.

The firing atmosphere of the green chip may be appropriately determined according to the type of the conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure of the firing atmosphere Is preferably 10 ⁻¹⁰ to 10 ⁻³ Pa, more preferably 10 ^{−10 to} 6 × 10 ⁻⁵ Pa. If the oxygen partial pressure during firing is too low, the conductive material of the internal electrode may be abnormally sintered and interrupted, and if the oxygen partial pressure is too high, the internal electrode may be oxidized.

  The holding temperature of baking is 1000-1400 degreeC, More preferably, it is 1100-1250 degreeC. This is because if the holding temperature is too low, the densification becomes insufficient, and if the holding temperature is too high, the capacity-temperature characteristics deteriorate due to electrode discontinuity due to abnormal sintering of the internal electrode or diffusion of the internal electrode material. As other firing conditions, the heating rate is 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, the temperature holding time is 0.5 to 8 hours, more preferably 1 to 3 hours, and the cooling rate. Is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the firing atmosphere is desirably a reducing atmosphere. As the atmosphere gas, for example, a mixed gas of nitrogen gas and hydrogen gas is humidified. It is desirable to use it.

When firing in a reducing atmosphere, it is desirable to anneal (heat treat) the sintered body of the capacitor chip. Annealing is a process for re-oxidizing the dielectric layer, thereby increasing the insulation resistance. The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻⁴ Pa or more, more preferably 10 ⁻¹ to 10 Pa. If the oxygen partial pressure is too low, reoxidation of the dielectric layer 2 becomes difficult, and if the oxygen partial pressure is too high, the internal electrode layer 3 may be oxidized. The holding temperature at the time of annealing is 1150 ° C. or lower, more preferably 800 to 1100 ° C. If the holding temperature is too low, re-oxidation of the dielectric layer is insufficient and the insulation resistance deteriorates. On the other hand, if the holding temperature is too high, the internal electrode is oxidized and the capacity is lowered, and it reacts with the dielectric substrate, so that the capacity-temperature characteristic and the insulation resistance are deteriorated.

  The capacitor fired body (capacitor element body 3) obtained as described above is subjected to end surface polishing by, for example, barrel polishing or sand blasting, and the external electrode paste is printed or transferred and fired to form the external electrode 4. . The firing conditions of the external electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a mixed gas of humidified nitrogen gas and hydrogen gas. Next, a coating layer (pad layer) is formed on the surface of the external electrode 4 by plating or the like as necessary. The external electrode paste may be adjusted in the same manner as the above internal electrode layer ink.

  The multilayer ceramic capacitor of this embodiment manufactured in this way has excellent capacitance-temperature characteristics, does not cause a decrease in capacitance value, and exhibits variations in insulation resistance (IR) and breakdown voltage (BDV). Can improve. As a result, the quality level of the capacitor in a high temperature and high humidity environment is improved.

  Moreover, the multilayer ceramic capacitor manufactured in this way is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

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

  Next, the present invention will be described in more detail with reference to examples that further embody the embodiment of the present invention. However, the present invention is not limited to these examples. In this example, a sample of a multilayer ceramic capacitor was produced according to the following procedure.

As the starting material, BaTiO ₃ particles synthesized by the oxalate method were used, and the average particle size of the starting material at that time was 0.22 μm (BET value 4.8 m ² / g). In particular, the influence on the characteristics of the production method of BaTiO ₃ particles is small, and there is no problem even if it is a solid phase method or a hydrothermal method.

In the present embodiment, the BaTiO ₃ 100, which is a main component, satisfies the X5R characteristic (capacitor showing a change in capacitance value within ± 15% in the temperature range of −25 ° C. to + 85 ° C.) in this embodiment. 1.0 mol of Mg in terms of MgO with respect to mol, 0.3 mol of Dy ₂ O ₃ which is a rare earth element oxide, and 0.2 mol of Yb ₂ O ₃ which is a rare earth element oxide, transition metal oxide Example 1 was prepared by adjusting 0.1 M of Mn ₃ O ₄ and 1.95 mol of glass component BaSiO _{3 so as} to obtain a desired dielectric composition.

The rare earth metal oxides A and B are not limited to Dy ₂ O ₃ and Yb ₂ O _3, but other Ho ₂ O ₃ , Y ₂ O ₃ , Er ₂ O _{3 and the} like may be used depending on the application. There is no problem even if it is used, and selection of a combination of the plural types can sufficiently achieve the object.

  Further, Ba, Ca, etc., which are alkaline earth metals other than Mg, may be added, but care must be taken in using them because they affect the firing conditions.

Further, the glass component may be an oxide composed of Ba and Si, and the ratio of Ba and Si can be arbitrarily adjusted, and there is no problem because they are added in different properties. However, BaSiO ₃ is more preferable because the BaTiO ₃ firing condition sensitivity tends to change when the amount of Ba becomes excessive. Furthermore, since an excess of the Ba component affects the firing conditions of the core BaTiO ₃ , 0.5 to 2.0 mol is more preferable, and less than 2.0 mol is sufficient.

Next, as the electrode ink for internal electrodes, the main component nickel powder is SP02 manufactured by Sakai Chemical Industry with an average particle diameter of 0.2 μm, and Mg is converted to 1.0 mol in terms of MgO with respect to 100 parts by weight of nickel. Suppressing the mixing and pulverization level of the dielectric composition (particle size 0.22 μm, BET 4.8 m ² / g) used for the dielectric layer, and average particle size twice that of substantially the same particle of the same composition in the dielectric 2 parts by weight of 0.44 μm diameter particles and 10 parts by weight of substantially the same particles as the dielectric composition were prepared.

  Subsequently, Sekisui Chemical's butyral resins BM-S, BH-S, and BL-S were blended in a ratio of 1: 2: 1, respectively, and a plasticizer added at 45% to the resin was an organic material of butyl acetate and butyl cellosolve. After being made into a vehicle together with a solvent, it was prepared with facilities such as a disperser and a three-roller so as to be sufficiently mixed and kneaded with each powder.

  These were diluted with an organic solvent such as butyl acetate or butyl cellosolve, and passed through a 10 μm, 5 μm, or 3 μm filter to filter agglomerates, impurities, and the like, thereby preparing a predetermined electrode ink. In the present invention, the ratio of each powder to the resin binder is not particularly limited as long as the electrode pattern can form a normal smooth surface, but is preferably about 3 to 7%. Similarly, various combinations can be selected in consideration of the rigidity of the electrode sheet.

  The electrode pattern of the present invention is obtained by diluting the obtained electrode ink of Example 1 to 69% with a solvent and using a gravure printing machine to dry the gravure plate so that the thickness becomes 0.9 μm. It was produced by adjusting the speed, drying heater temperature, and the like. The electrode pattern may be produced by a method other than the gravure printing method and the like, and there is no problem as long as a clean pattern such as a thermal transfer method can be obtained by using the obtained electrode ink. The compositions and combinations of Examples 2 and later and Comparative Examples were adjusted as shown in (Table 1).

  Next, 30 parts by weight of butyl acetate as a dispersion medium is added to 100 parts by weight of the dielectric ceramic composition, and 500 parts by weight of zirconia cobblestone having a diameter of 10 mm is added. The dielectric ceramic composition, dispersion medium and cobblestone blended as described above are placed in a ball mill and then mixed for 12 hours.

  Thereafter, 8 parts by weight of a butyral resin-based binder (for example, BM-S manufactured by Sekisui Chemical Co., Ltd.) as a resin binder with respect to 100 parts by weight of the dielectric ceramic composition powder containing a dispersion medium mixed by a ball mill, a plasticizer After adding 4 parts by weight of benzyl butyl phthalate, the blend was sufficiently dispersed in a crushing mill, a medium stirring mill or the like to form a slurry, which was a dielectric slurry.

  Next, the dielectric slurry was formed into a dielectric green sheet having a thickness of about 12 μm by a doctor blade method or the like. An internal electrode pattern is printed and formed on the dielectric green sheet thus obtained using nickel electrode ink, and one end of each internal electrode is alternately drawn out from the opposing end faces so that the opposing end faces can be connected in parallel. 100 dielectric layers and 100 electrode layers were laminated to obtain a laminate of 100 layers.

Thereafter, the obtained laminate was debindered at 450 ° C. in an N ₂ atmosphere, and then fired at a temperature of 1180 ° C. in a reducing atmosphere in which the nickel of the internal electrode was not oxidized. After forming the electrode with a nickel electrode paste, copper and a solder electrode were formed on the nickel electrode by a plating method to improve solder wettability, thereby obtaining a chip-shaped multilayer ceramic capacitor.

  Delamination and structural defects were judged by appearance observation before firing and after completion of sintering, and the short-circuit rate was data for 100 sample samples.

  In addition, the dielectric constant and the like, which are electrical characteristics of the multilayer ceramic capacitor thus obtained, were measured under the measurement conditions of 1.0 kHz and 0.5 Vrms using an LCR meter (4284A manufactured by Agilent). The higher the dielectric constant, the better. However, considering the balance with the DC bias characteristics and the like, approximately 3000 is required, but it is particularly limited as long as the capacitance can be adjusted by the number of dielectric layers and the thickness of the dielectric layer. It is not a thing. The capacity setting of the prepared sample was 2.0 μF (tolerance ± 10%), and the capacity reduction was examined.

  In addition, the dielectric breakdown voltage (BDV) was measured by an oscilloscope (Tektronix TDS210) by applying a DC power supply voltage (PADIK-0.2L, manufactured by Kikusui) to both electrodes of the multilayer ceramic capacitor. At this time, a sample of the multilayer ceramic capacitor to be measured was prepared by manufacturing a multilayer body in which the dielectric thickness was adjusted to 1.5 μm so that the state of dielectric breakdown could be clearly understood.

Furthermore, the insulation resistance after applying a voltage of DC 72V for 72 hours at 150 ° C. for 100 samples of the multilayer ceramic capacitor was measured, and the number of samples whose value was 1 × 10 ⁷ Ω or less was examined. . It can be said that the higher the number of samples with an insulation resistance of 10 ⁷ Ω or higher under these conditions, the higher the durability and the higher the reliability.

  The electrical characteristics of each of the produced multilayer ceramic capacitor samples are shown in (Table 1), the capacitance is measured in the temperature range from −55 ° C. to 85 ° C., and the rate of change in capacitance temperature based on the capacitance value of 25 ° C. A representative example of the result of obtaining is shown.

Here, the temperature characteristic ΔCt of the capacitance in (Table 1) was obtained according to the following equation. (Table 1
) Shows X5R characteristics, and DC85 is annealed at 125 ° C. for 30 minutes and then cooled to −55 ° C. after the measurement of TC85, and when the measurement system is stabilized, DC4V is applied and similarly at each temperature. 3 shows a DC bias characteristic obtained by examining the capacitance change.

TC85 = {(C85−C25) / C25} × 100 (%)
DC85 = {(DC85−C25) / C25} × 100 (%)
However, C25 shows the electrostatic capacitance of 25 degreeC, C85 shows the electrostatic capacitance in 85 degreeC.

  As is clear from the results of (Table 1), the embodiment according to the present invention achieves an appropriate temperature characteristic that can be practically used as the X5R characteristic while maintaining a low electrostatic capacity drop, and a high dielectric breakdown voltage is obtained. It was.

  However, in Comparative Example 1 in which the common material is outside the scope of the present invention, although capacity reduction is not observed, structural defects, deterioration of the short-circuit rate, and temperature characteristics are observed, which is not practical.

  In Comparative Examples 2 and 7 in which the addition amount of the dielectric core particles out of the scope of the present invention is the common material, the structural defect is eliminated when the amount exceeds the specified value, but the temperature characteristic is significantly deteriorated. As a result, the structural defect deteriorated and the capacitance value decreased.

  Further, in Comparative Example 3 in which substantially the same particles as the dielectric layer were not added, delamination and structural defects occurred frequently, the dielectric layer was poorly densified, and the dielectric breakdown voltage was low.

  Further, in Comparative Examples 4 and 6 in which the amount of particles substantially the same as that of the dielectric layer is out of the scope of the present invention, although it is excellent in eliminating structural defects, the capacitance value is greatly reduced, and a predetermined tolerance I was not satisfied.

  Of the common materials, in Comparative Example 5 in which the average particle size of the core particles to be added was outside the range of the present invention, the specified values could not be satisfied in all items other than the decrease in capacity.

  As described above, the electrode ink for internal electrodes, the electrode pattern, and the multilayer ceramic capacitor using the same according to the present invention are substantially the same particles having the same composition contained in the dielectric layer with respect to 100 parts of the main component nickel particles. Particles having an average particle size of 1.5 to 3.0 times the average particle size of the core particles and 0.5 to 3.0 times the same as that of the dielectric layer. 3 to 15 parts, by suppressing structural defects that are likely to occur at the time of firing, it is possible to minimize the decrease in the capacitance value and to stabilize the temperature characteristics of the capacitance, and to have a high dielectric breakdown voltage characteristic It is possible to provide a highly reliable multilayer ceramic capacitor having

Here, the production method of BaTiO ₃ is not particularly limited and is preferably as fine as possible, but the size is not particularly limited, and more preferably in DSC measurement (differential calorimetric analysis) of BaTiO ₃ powder. It is desirable to use a material in which no clear peak is observed in the temperature range of 25 ° C. to 150 ° C.

  The multilayer ceramic capacitor of the present embodiment manufactured in this way has excellent capacitance-temperature characteristics, has a small decrease in capacitance value, and exhibits variations in insulation resistance (IR) and breakdown voltage (BDV). Can improve. As a result, it was proved that the quality level of the capacitor was improved.

  Moreover, the multilayer ceramic capacitor manufactured in this way is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

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

  For example, the dielectric ceramic composition obtained by the manufacturing method according to the present invention is not used only for a multilayer ceramic capacitor, but may be used for other multilayer ceramic capacitors on which a dielectric layer is formed.

  The electrode ink, electrode pattern, and multilayer ceramic capacitor using the same according to the present invention have excellent capacity-temperature characteristics that are excellent in reduction resistance during firing and that do not cause structural defects after firing. Therefore, it is useful for electronic control circuits of automobiles, etc., in which the temperature stability of the circuit is strictly required.

Sectional drawing of the multilayer ceramic capacitor in one embodiment of this invention Microstructure model diagram of composition particles constituting dielectric layer and internal electrode of the same multilayer ceramic capacitor Microstructure model diagram of composition particles constituting dielectric layer and internal electrode of conventional multilayer ceramic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric layer 1A Dielectric particle 2 Internal electrode layer 2C Cavity 3 Capacitor element body 4 External electrode 8 Nickel particle 8B Internal electrode addition particle A
8C Internal electrode additive particle B

Claims (3)

1. An electrode ink for forming the internal electrode of a multilayer ceramic capacitor formed by alternately laminating internal electrodes and dielectric layers, the electrode ink comprising at least nickel particles and a resin binder as main components, and About 100 parts of the nickel particles are substantially the same particles of the same composition contained in the dielectric layer, and the average particle size is approximately 1.5 to 3.0 times the average size of the core particles. An electrode ink comprising 0.5 to 3.0 parts of the same particles and 3 to 15 parts of particles substantially the same as the dielectric layer.
2. A sheet for an internal electrode of a multilayer ceramic capacitor in which internal electrodes and dielectric layers are alternately stacked, wherein the internal electrode is composed of a resin binder, main component nickel particles, and 100 parts of the nickel particles. The substantially identical particles contained in the dielectric layer and having the same composition and having an average particle size of 1.5 to 3.0 times the average size of the core particles are 0.5 to 3. An internal electrode sheet comprising 0 part and 3 to 15 parts of particles substantially the same as the dielectric layer.
3. In a multilayer ceramic capacitor in which a dielectric layer composed of a dielectric ceramic composition having a particle diameter of 0.25 μm or less and a BET value of 4.5 to 10 m ² / g, and internal electrodes composed of nickel powder and a resin binder are alternately laminated, The internal electrodes are substantially the same particles of the same composition contained in the dielectric layer with respect to 100 parts of the main component nickel particles, and the average particle size is 1.5 to 3.0 of the average size of the core particles. A multilayer ceramic capacitor comprising 0.5 to 3.0 parts of substantially the same particles having a double particle diameter and 3 to 15 parts of particles which are substantially the same as the dielectric layer.

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