JP2011129841A - Method of manufacturing electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an electronic component that prevents delamination caused on an interface between an interior part and an exterior part which form the electronic component, and increases the strength of the exterior part by reducing the difference in sintering degree between the interior part and exterior part. <P>SOLUTION: The method of manufacturing the electronic component includes the processes of: forming the interior part by alternately laminating an interior dielectric layer formed using an interior green sheet and an internal electrode layer formed using an internal electrode pattern layer, and laminating at least one exterior dielectric layer formed using an exterior green sheet to obtain a green chip; and baking the green chip to obtain an element main body, the exterior green sheet containing first ceramic particles and second ceramic particles by predetermined amounts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Electronic parts such as multilayer ceramic capacitors are widely used as small, large-capacity, and highly reliable electronic parts.

  The capacitor element body constituting such a multilayer ceramic capacitor has an interior portion in which a plurality of interior dielectric layers and internal electrode layers are alternately laminated. An exterior part is arrange | positioned at the both ends of the lamination direction of an interior part. The exterior part has a structure in which at least one exterior dielectric layer is laminated.

  Here, since the interior green sheet constituting the interior dielectric layer is manufactured using a paste suitable for thinning, the density is relatively high. On the other hand, the density of the exterior green sheet for forming the exterior part is low, which ensures the air permeability of the exterior green sheet, improves the air release property during drying and binder removal, and the adhesion between layers This is because defects and cracks during binder removal can be reduced.

  Since the exterior green sheet has a lower density than the interior green sheet, the exterior green sheet is harder to sinter than the interior green sheet, and there is a difference in the degree of sintering during firing between the interior part and the exterior part. is there. For this reason, uneven burning may occur in the exterior part, or delamination may occur at the interface between the interior part and the exterior part. In addition, there is a problem in that the unevenness of the exterior part decreases due to the occurrence of uneven burning in the exterior part, resulting in defects in the product. In recent years, more and more of these phenomena have been observed as the thickness of the exterior portion has become thinner due to the trend toward miniaturization of electronic components.

  In order to solve such a problem, Patent Document 1 discloses a method of adjusting sinterability by adding deformed crystal particles to an exterior part. However, it is difficult to adjust the composition, material, or heat treatment conditions for forming irregular crystal grains, and there is a problem that performance varies from product to product.

  Further, as a conventional technique, there is a method of adjusting sinterability by adding glass, but it is difficult to adjust the addition amount, and there is a problem that performance varies depending on products even if a predetermined amount is added.

JP-A-9-31234

  The present invention has been made in view of such a situation, and the object thereof is to reduce the difference in the degree of sintering between the interior part and the exterior part that form the electronic component, and prevent delamination that occurs at the interface between the interior part and the exterior part. At the same time, it is to provide an electronic component manufacturing method capable of increasing the strength of the exterior part.

  In order to achieve the above-mentioned object, the present inventors pay attention to the ceramic particles contained in the exterior part of the electronic component, and by including a predetermined amount of specific ceramic particles in the exterior dielectric layer, the interior part and the exterior part are included. It has been found that the difference in the degree of sintering in the part can be reduced, and the present invention has been completed.

That is, the method for manufacturing a multilayer ceramic capacitor according to the present invention includes:
An interior dielectric layer formed using an interior green sheet and an internal electrode layer formed using an internal electrode pattern layer are alternately stacked to obtain an interior portion, and formed using an exterior green sheet. Laminating at least one exterior dielectric layer on the interior part to obtain a green chip;
A step of obtaining an element body by firing the green chip, and a method of manufacturing an electronic component comprising:
The exterior green sheet includes first ceramic particles and second ceramic particles,
The first ceramic particles include a main component of a dielectric material contained in the interior green sheet and a subcomponent of a dielectric material contained in the interior green sheet,
The second ceramic particles are composed of a main component of a dielectric material contained in the interior green sheet,
When the value of 50% of the cumulative distribution of the particle size of the first ceramic particles is d _α μm and the value of 50% of the cumulative distribution of the particle size of the second ceramic particles is d _β μm, d _α and d _β The relationship is 1.2 ≦ d _α / d _β ≦ 3.0,
When the second ceramic particles contained in the exterior green sheet are 1 part by weight, the content ratio of the first ceramic particles contained in the exterior green sheet is 4.0 parts by weight or more and 9.0 parts by weight or less. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the difference in the sintering degree of the interior part of an electronic component and an exterior part can be reduced, and the manufacturing method of the electronic component which can eliminate the burning unevenness of an exterior part and an intensity | strength insufficient can be provided.

  Preferably, the internal electrode pattern layer includes the second ceramic particles.

Preferably, the particle diameter of the first ceramic particles is 0.35 ≦ d _α ≦ 0.50.

Preferably, the relationship between d _α and d _β is 1.5 ≦ d _α / d _β ≦ 1.8.

  The first ceramic particles may have a structure in which at least a part of a main component of the dielectric material contained in the interior green sheet is coated with a subcomponent of the dielectric material contained in the interior green sheet.

  The first ceramic particles have a structure in which at least a part of the main component of the dielectric material contained in the interior green sheet and at least a part of the subcomponent of the dielectric material contained in the interior green sheet are in solid solution. Also good.

  Preferably, the electronic component is a multilayer ceramic capacitor.

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

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a capacitor element body constituting a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 3A is a schematic view showing first ceramic particles according to the method for manufacturing a multilayer ceramic capacitor of one embodiment of the present invention, and FIG. 3B is a second ceramic particle according to one embodiment of the present invention. It is a schematic diagram which shows. FIG. 4 a is a process schematic diagram showing a manufacturing process of the multilayer ceramic capacitor shown in FIG. 1. FIG. 4B is a process schematic diagram showing a continuation process of FIG. 4A. FIG. 4c is a process schematic diagram showing a continuation process of FIG. 4b. FIG. 4d is a process schematic diagram showing a continuation process of FIG. 4c. FIG. 4e is a process schematic diagram showing a continuation process of FIG. 4d. FIG. 4f is a process schematic diagram showing a continuation process of FIG. 4e. FIG. 5 is an explanatory diagram of a method for measuring the bending strength in the embodiment of the present invention. FIG. 6 is an explanatory diagram of a method for measuring the protrusion amount δ in the embodiment of the present invention. FIG. 7 is a graph showing the protrusion amount of each sample in the example of the present invention.

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

  In the present embodiment, a multilayer ceramic capacitor will be described as an example of an electronic component.

  The electronic component manufactured by the manufacturing method according to an embodiment of the present invention is not particularly limited, and may be a multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, or other surface mount (SMD) chip type. Examples include electronic parts. In this embodiment, a multilayer ceramic capacitor is illustrated.

Overall Configuration of Multilayer Ceramic Capacitor As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention has a capacitor element body 10. As shown in FIG. 2, the capacitor element body 10 includes an interior portion 22a and an exterior portion 22b, and the exterior portions 22b are disposed at both ends of the interior portion 22a in the stacking direction. The interior portion 22a has a structure in which interior dielectric layers 2a and internal electrode layers 3 are alternately stacked, and the exterior portion 22b has at least one exterior dielectric layer 2b. A pair of external electrodes 4 are formed on both end portions of the capacitor element body 10 so as to be electrically connected to the internal electrode layers 3 arranged alternately in the capacitor element body 10.

  The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

(Interior dielectric layer)
The interior dielectric layer according to the embodiment of the present invention is obtained by firing an interior green sheet. The main component and subcomponent of the dielectric material contained in the interior green sheet are not particularly limited, and examples thereof include the main component and subcomponent of the dielectric material that satisfy the X8R characteristics of the EIA standard shown below.

The dielectric material as a main component, having, for example, a composition formula _{(Ba 1-x Ca x)} m (Ti 1-y Zr y) dielectric oxide expressed by _{O 3.} At this time, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the above formula.

  In the above formula, x is preferably 0 ≦ x ≦ 0.15. x represents the number of Ca atoms, and the phase transition point of the crystal can be arbitrarily shifted by changing the symbol x, that is, the Ca / Ba ratio. Therefore, the capacity temperature coefficient and the relative dielectric constant can be arbitrarily controlled.

In the above formula, y is preferably 0 ≦ y ≦ 1.00. Although y represents the number of Ti atoms, there is a tendency that the reduction resistance is further increased by substituting ZrO ₂ which is not easily reduced as compared with TiO ₂ .

  In the above formula, m is preferably 0.995 ≦ m ≦ 1.020. By making m 0.995 or more, it is possible to prevent the formation of a semiconductor for firing in a reducing atmosphere, and by making m to 1.020 or less, dense sintering can be achieved without increasing the firing temperature. You can get a body.

The dielectric material contains, for example, the following first to fourth subcomponents as subcomponents. That is, the first subcomponent including at least one selected from MgO, CaO, BaO and SrO, the second subcomponent including silicon oxide as a main component, V ₂ O ₅ , MoO ₃ and WO _{3 are} selected. A third subcomponent including at least one of the above and an oxide of R (where R is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) And a fourth subcomponent including at least one selected from Yb, Lu).

The ratio of each of the subcomponents is preferably the first subcomponent: 0.1-5 mol with respect to 100 mol of the main component
Second subcomponent: 1 to 10 mol,
Third subcomponent: 0.01 to 0.2 mol,
4th subcomponent: 0.1-12 mol,
It is.

The ratio of the fourth subcomponent is not the molar ratio of the R oxide, but the molar ratio of the R element alone. That is, for example, as the fourth subcomponent (oxide of R), when using an oxide of Y, that the ratio of the fourth subcomponent being 1 mole ratio of Y ₂ O ₃ Instead of 1 mole , Meaning that the ratio of the Y element is 1 mol.

  By containing these first to fourth subcomponents in addition to the main component having the predetermined composition, the capacity-temperature characteristics can be improved while maintaining a high dielectric constant, and in particular, the EIA standard X8R The characteristics can be satisfied. The preferred contents of the first to fourth subcomponents are as described above, and the reason is as follows.

  The first subcomponent (MgO, CaO, BaO and SrO) exhibits an effect of flattening the capacity-temperature characteristics. The composition ratio of each oxide in the first subcomponent is arbitrary.

The second subcomponent (silicon oxide) contains silicon oxide as a main component, preferably SiO ₂ , MO (where M is at least one element selected from Ba, Ca, Sr and Mg), Li ₂ O. And at least one selected from B ₂ O ₃ . The second subcomponent mainly acts as a sintering aid, but has an effect of improving the defective rate of the initial insulation resistance when the layer is thinned.

In the present embodiment, as the second _{subcomponent, (Ba, Ca) x SiO} 2 + x ( however, x = 0.7 to 1.2) may be used a compound represented by.

The third subcomponent (V ₂ O ₅ , MoO ₃ and WO ₃ ) exhibits the effect of flattening the capacity-temperature characteristics at the Curie temperature or higher and the effect of improving the IR lifetime. The constituent ratio of each oxide in the third subcomponent is arbitrary.

  The fourth subcomponent (R oxide) exhibits the effect of shifting the Curie temperature to the high temperature side and the effect of flattening the capacity-temperature characteristics.

  The thickness of the inner dielectric layer is preferably 0.5 to 10 μm, more preferably 0.5 to 5.0 μm per layer. The thickness of the exterior dielectric layer is preferably 3.0 to 20 μm, more preferably 3.0 to 6.0 μm per layer. Even if the multilayer ceramic capacitor of this embodiment has such a thin dielectric layer, there is no difference in the degree of sintering between the interior part and the exterior part, and the burning unevenness of the exterior part is reduced. be able to. In addition, the lamination | stacking number of an interior part is about 2-300, and the lamination | stacking number of an exterior part is 5-30.

(Exterior dielectric layer)
The exterior dielectric layer is obtained by firing the exterior green sheet. In the embodiment of the present invention, the exterior green sheet includes a predetermined amount of first ceramic particles and second ceramic particles.

  Here, as shown in FIG. 3A, the first ceramic particles include a main component of a dielectric material contained in the interior green sheet and a subcomponent contained in the interior green sheet. As the structure of the first ceramic particles, as shown in FIG. 3 (A), the subcomponent of the dielectric material may coat the entire surface or a part of the surface of the main component of the dielectric material, Further, all or part of the main component and subcomponent of the dielectric material may be dissolved.

  As a method for producing the first ceramic particles, for example, the main component and the subcomponent of the dielectric material are prepared, and the main component and the subcomponent are mixed, slurried, and calcined. It can also be obtained by mixing and slurrying the subcomponents, adding the remaining subcomponents to the first calcined, mixing and slurrying, and performing the second calcining.

  When the first ceramic particles include the main component and the subcomponent of the dielectric material, the subcomponent of the dielectric material serves as a sintering aid and promotes the sintering of the exterior green sheet. Thereby, the difference in the degree of sintering between the interior part and the exterior part is reduced, delamination occurring at the interface between the interior part and the exterior part can be prevented, and the strength of the exterior part can be increased.

  As shown in FIG. 3B, the second ceramic particles are composed of the main component of the dielectric material. The second ceramic particles having a particle diameter smaller than that of the first ceramic particles can serve as a sintering aid and promote the sintering.

Further, when the value of 50% of the cumulative distribution of the particle diameter of the first ceramic particles (hereinafter referred to as “D50”) is d _α μm and the D50 of the second ceramic particles is d _β μm, d _α The relationship of d _β is 1.2 ≦ d _α / d _β ≦ 3.0, more preferably 1.5 ≦ d _α / d _β ≦ 1.8. By d _alpha / d _beta is included in this range, it is possible to prevent delamination caused by interface interior portion and exterior portion, it is possible to increase the strength of the exterior part.

d _α is preferably 0.35 ≦ d _α ≦ 0.50, more preferably 0.35 ≦ d _α ≦ 0.40. d _alpha can be prevented delamination occurring at the interface between the interior portion and exterior portion by being included in this range, it is possible to increase the strength of the exterior part.

  When the second ceramic particles contained in the exterior green sheet is 1 part by weight, the content ratio of the first ceramic particles contained in the exterior green sheet is 4.0 parts by weight or more and 9.0 parts by weight or less, preferably Is 4.0 parts by weight or more and 5.7 parts by weight or less. When the content ratio of the first ceramic particles is included in this range, delamination that occurs at the interface between the interior portion and the exterior portion can be prevented, and the strength of the exterior portion can be increased.

(Internal electrode layer 3)
Although the electroconductive particle contained in the internal electrode layer 3 is not specifically limited, Since the constituent material of the dielectric material layer 2 has reduction resistance, a base metal can be used. As the base metal, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 wt% or less. The thickness of the internal electrode layer may be appropriately determined according to the application, etc., but it is usually preferably about 0.5 to 5 μm, particularly preferably about 0.5 to 2.5 μm.

  The internal electrode layer is obtained by firing the internal electrode pattern layer. However, in the embodiment of the present invention, the internal electrode pattern layer preferably contains the second ceramic particles, more preferably conductive particles. It is contained in 10 to 30 parts by weight with respect to 100 parts by weight. By including the second ceramic particles in the internal electrode pattern layer, the timing of starting the sintering of the internal electrode pattern layer is delayed, the timing of starting the sintering of the interior portion is delayed, and the internal electrode layer and the interior dielectric layer Generation | occurrence | production of the distortion in an interior part can be suppressed by reducing the difference in the timing of a sintering start. In addition, it is possible to suppress delamination at the interface between the interior part and the exterior part caused by strain in the interior part, and to increase the strength of the exterior part.

(External electrode)
The base metal contained in the external electrode 4 is not particularly limited, but inexpensive Ni, Cu, and alloys thereof can be used. The thickness of the external electrode may be appropriately determined according to the use, etc., but is usually preferably about 10 to 50 μm.

Manufacturing Method of Multilayer Ceramic Capacitor After the multilayer ceramic capacitor according to the embodiment of the present invention is manufactured, a green chip is manufactured by a normal printing method or a sheet method using a paste, and fired. It is manufactured by printing or transferring an external electrode and baking. Hereinafter, the manufacturing method will be specifically described.

  First, first ceramic particles and second ceramic particles contained in the exterior dielectric layer paste and the interior dielectric layer paste are prepared, and these are made into a paint, and then the exterior dielectric layer paste and the interior dielectric layer paste Adjust.

(Interior dielectric layer paste, exterior dielectric layer paste)
The interior dielectric layer paste is an organic paint obtained by kneading a dielectric material and an organic vehicle. The exterior dielectric layer paste is an organic paint obtained by kneading the first ceramic particles, the second ceramic particles, and the organic vehicle.

  The interior dielectric layer paste and the exterior dielectric layer paste may be water-based paints using a water-based vehicle instead of the organic vehicle. The water-soluble resin used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, or the like may be used.

  As the dielectric material, the above-mentioned oxide, a mixture thereof, or a composite oxide can be used. In addition, various compounds that become the above-described oxide or composite oxide by firing, for example, carbonate, oxalate, It can be appropriately selected from nitrates, hydroxides, organometallic compounds, and the like, and can also be used as a mixture. What is necessary is just to determine content of each compound in a dielectric material powder so that it may become a composition of the above-mentioned dielectric material after baking.

  An organic vehicle is obtained by dissolving a resin in an organic solvent. The resin used for the organic vehicle is not particularly limited, and may be appropriately selected from ordinary various resins such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, toluene, and the like, depending on a method to be used such as a printing method or a sheet method.

(Internal electrode layer paste)
The internal electrode layer paste is a paint in which conductive particles and an organic vehicle are kneaded, and is preferably further added with second ceramic particles.

(External electrode paste)
The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

(Green chip)
The green chip is composed of an exterior green chip precursor and an interior green chip precursor. The exterior green chip precursor is composed of at least one exterior green sheet, and the interior green chip precursor has a structure in which an interior green sheet and an internal electrode pattern layer are laminated.

(1) Exterior Green Chip Precursor The exterior green chip precursor is obtained by laminating at least one exterior green sheet 42b. Specifically, as shown in FIG. 4a, the exterior dielectric layer paste is applied to the surface of the support sheet 40 composed of, for example, a PET film by, for example, a doctor blade method to form the exterior green sheet 42b, Next, as shown in FIG. 4b, an exterior green sheet 42b is laminated on a pressing jig 41 such as a mold. The exterior green sheet 42b becomes the exterior dielectric layer 2b shown in FIG. 1 after firing.

(2) Interior Green Chip Precursor The interior green chip precursor is obtained by forming the above-described interior dielectric layer paste and internal electrode layer paste as follows.

  As shown in FIG. 4c, for example, an interior dielectric layer paste is applied to the surface of a support sheet 40 made of, for example, a PET film by a doctor blade method or the like to form an interior green sheet 42a. The interior green sheet 42a becomes the interior dielectric layer 2a shown in FIG. 1 after firing.

  Next, as shown in FIG. 4d, the internal electrode pattern layer 43 is formed by applying the internal electrode layer paste in a predetermined pattern on the surface of the interior green sheet 42a formed on the support sheet 40. The internal electrode pattern layer 43 becomes the internal electrode layer 3 shown in FIG. 1 after firing.

  The method for forming the internal electrode layer 3 in FIG. 4d is not particularly limited as long as the layer can be formed uniformly. For example, a thick film forming method such as a screen printing method or a gravure printing method using an internal electrode layer paste, Or thin film methods, such as vapor deposition and sputtering, are illustrated.

  In the present embodiment, after the internal electrode pattern layer 43 is formed on the surface of the interior green sheet 42a by the printing method, or before that, the surface gap of the interior green sheet 42a where the electrode layer 43 shown in FIG. As shown in FIG. 4E, a blank pattern layer 45 having substantially the same thickness as the internal electrode layer 43 may be formed in the (margin pattern portion 44). The blank pattern layer 44 is formed in order to prevent a step between the internal electrode pattern layers 43 on the green sheet 42a.

  Since the electrode step absorption printing paste for forming the blank pattern layer 44 is integrated with the interior dielectric layer 42a after firing, it is preferable that the dielectric material used for the interior dielectric layer paste and an organic binder are included.

  The dielectric raw material is preferably contained in the electrode level difference absorbing printing paste in an amount of 30 to 70% by weight, more preferably 40 to 55% by weight. If the content of the ceramic powder is too small, the paste viscosity becomes small and printing becomes difficult. Moreover, when there is too much content rate of ceramic powder, it exists in the tendency for it to become difficult to make printing thickness thin.

  As shown in FIG. 4f, the interior green sheet 42a on which the internal electrode pattern layer 43 and the blank pattern layer 45 are formed is peeled off from the support sheet 40 and sequentially laminated to form a laminate. The obtained laminated body 410 is pressed by pressing using a pressing jig, hydrostatic pressing, or the like, and presses the green sheets together. In the above, a method of laminating a plurality of exterior green sheets and then sequentially laminating interior green sheets is illustrated, but the laminating method is not limited, and in addition, a plurality of interior green sheets are separately laminated. Then, a method of laminating a plurality of laminated interior green sheets on a plurality of laminated exterior green sheets may be used.

(Cutting of laminated body 410)
A plurality of green chips are formed by cutting the stacked body 410 into a lattice shape.

Green chip firing The green chip is barrel-polished, washed with water, dried and fired. Note that the green chip is subjected to a binder removal process before firing. The binder removal treatment 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 in the binder removal atmosphere is set. It is preferable to be 10 ⁻⁴⁵ to 10 ⁵ Pa. When the oxygen partial pressure is included in the above range, the binder removal effect is increased and oxidation of the internal electrode layer tends to be reduced.

As binder removal conditions other than those described above, the temperature rising rate is preferably 5 to 300 ° C./hour, the holding temperature is preferably 180 to 400 ° C., and the temperature holding time is preferably 0.5 to 24 hours. Also, the firing atmosphere is preferably the air or a reducing atmosphere, as the atmosphere gas in the reducing atmosphere, it is preferable, for example, a wet mixed gas of N ₂ and H _2.

The atmosphere at the time of green chip firing may be appropriately determined according to the type of 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 content in the firing atmosphere The pressure is preferably 10 ⁻⁷ to 10 ⁻³ Pa. When the oxygen partial pressure is included in the above range, the conductive material of the internal electrode layer can suppress abnormal sintering, and discontinuity can be prevented.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1100-1400 degreeC. When the holding temperature is included in the above range, the densification is sufficient, and electrode breakage due to abnormal sintering of the internal electrode layer can be prevented.

As other firing conditions, the heating rate is preferably 50 to 500 ° C./hour, the temperature holding time is preferably 0.5 to 8 hours, and the cooling rate is preferably 50 to 500 ° C./hour. Further, the firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ is preferably used by humidification.

When firing in a reducing atmosphere, it is preferable to anneal the capacitor element body. Annealing is a process for re-oxidizing the dielectric layer, and this can significantly increase the IR lifetime, thereby improving the reliability. The oxygen partial pressure in the atmosphere at annealing 0.1Pa or higher, the holding temperature 1100 ° C. or less, 0-20 hours retention time, it is preferable that the cooling rate to 50 to 500 ° C. / hour. Further, as the annealing atmosphere gas, for example, humidified N ₂ gas or the like is preferably used.

In the above-described binder removal processing, firing and annealing, for example, a wetter or the like may be used to wet the N ₂ gas or mixed gas. In this case, the water temperature is preferably about 5 to 75 ° C.

  The binder removal treatment, firing and annealing may be performed continuously or independently.

The capacitor element body obtained as described above is subjected to end surface polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is printed or transferred and baked 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 humidified mixed gas of N ₂ and H ₂ . Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  The multilayer ceramic capacitor according to the embodiment of the present invention thus manufactured is mounted on a printed board or the like 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, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component. However, the electronic component according to the embodiment of the present invention is not limited to the multilayer ceramic capacitor, and may be an electronic component having an exterior part and an interior part. Anything is fine. Moreover, although the dielectric material satisfying the X8R characteristic is shown as the dielectric material, the dielectric material according to the embodiment of the present invention is not limited to the dielectric material satisfying the X8R characteristic.

Sample 1
(Interior dielectric layer paste)
First, as a starting material for producing a dielectric material, a main component material (BaTiO ₃ ) and a subcomponent material were prepared. In this example, BaTiO ₃ particles having D50 of 0.45 μm were used as the main component material.

The following raw materials were used as subcomponent raw materials. Carbonates (first subcomponent: MgCO ₃ , fifth subcomponent: MnCO ₃ ) are used as raw materials for MgO and MnO, and oxides (second subcomponent: (Ba _0.6 Ca _{0. 4} ) SiO ₃ , third subcomponent: V ₂ O ₅ , fourth subcomponent: Yb ₂ O ₃ + Y ₂ O ₃ , sixth subcomponent: CaZrO ₃ , other subcomponents: Al ₂ O ₃ were used.

The second subcomponent (Ba _0.6 Ca _0.4 ) SiO ₃ is obtained by wet-mixing BaCO ₃ , CaCO ₃ and SiO ₂ with a ball mill for 16 hours, drying, and firing in air at 1150 ° C., It was manufactured by wet grinding with a ball mill for 100 hours. CaZrO _{3 as} the fifth subcomponent was produced by wet mixing CaCO ₃ and ZrO ₂ with a ball mill for 16 hours, drying, firing in air at 1150 ° C., and further wet pulverizing with a ball mill for 24 hours.

In addition, BaTiO _{3 as} a main component is obtained by weighing BaCO ₃ and TiO ₂ respectively, wet-mixing them for about 16 hours using a ball mill, drying them, and firing them in air at a temperature of 1100 ° C. Similar characteristics were obtained even when a ball mill was used for approximately 16 hours of wet pulverization. Further, the same characteristics were obtained even when BaTiO ₃ as the main component was produced by a hydrothermal synthesis method, an oxalate method or the like.

For these raw materials, the composition after firing is 100 mol of BaTiO _{3 as} a main component, MgCO ₃ : 1 mol, (Ba _0.6 Ca _0.4 ) SiO ₃ : 3 mol, V ₂ O ₅ : 0.1 mol, Yb ₂ O ₃ : 1.75 mol, Y ₂ O ₃ : 2 mol, MnCO ₃ : 0.374 mol, CaZrO ₃ : 2.0 mol, Al ₂ O ₃ : 1 mol And mixed with a ball mill for 16 hours and dried to obtain a dielectric material.

  Next, 100 parts by weight of the obtained dielectric material after drying, 4.8 parts by weight of acrylic resin, 100 parts by weight of ethyl acetate, 6 parts by weight of mineral spirit, and 4 parts by weight of toluene were mixed with a ball mill. The paste was made into a paste for an interior dielectric layer.

(External dielectric layer paste)
First, a main component material and a subcomponent material were prepared in the same amount as that used for the interior dielectric layer paste. Next, the main component raw material and Y ₂ O ₃ powder were wet-mixed and pulverized by a ball mill to form a slurry. The slurry was dried, calcined and pulverized to obtain a reacted raw material. The calcining conditions were as follows: temperature increase rate: 200 ° C./hour, holding temperature: 500 ° C., temperature holding time: 2 hours, atmosphere: air.

  Next, the remaining subcomponents are added to the obtained reacted raw material, mixed in a ball mill, and the obtained mixed powder is preliminarily calcined at 1200 ° C. to obtain calcined powder having a D50 of 0.45 μm. To obtain first ceramic particles. The first ceramic particles had subcomponents fixed on the surface of the main component raw material. Next, among the main component materials used in the interior dielectric layer paste as the second ceramic particles, those having a D50 of 0.10 μm were prepared. The obtained first ceramic particles and second ceramic particles were wet pulverized in a ball mill for 15 hours and dried. These were 4.8 parts by weight of acrylic resin, 100 parts by weight of ethyl acetate, and 6 parts by weight of mineral spirits. Then, 4 parts by weight of toluene was mixed with a ball mill to make a paste to obtain a paste for an exterior dielectric layer.

(Internal electrode layer paste)
3 parts of 40 parts by weight of organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol) and 10 parts by weight of butyl carbitol with respect to 100 parts by weight of Ni particles having an average particle diameter of 0.4 μm. This roll was kneaded into a paste to obtain an internal electrode layer paste.

(External electrode paste)
Paste obtained by kneading 100 parts by weight of Cu particles having an average particle size of 0.5 μm, 35 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose resin dissolved in 92 parts by weight of butyl carbitol) and 7 parts by weight of butyl carbitol Thus, an external electrode paste was obtained.

(Laminate manufacturing process)
A sheet was formed into a PET film by the doctor blade method and dried to form an exterior green sheet. At this time, the thickness of the exterior green sheet was 6.0 μm. Next, 30 layers of exterior green sheets were laminated on a pressing jig such as a mold.

  Next, the obtained interior dielectric layer paste was used to form a sheet on a PET film by a doctor blade method and then dried to form an interior green sheet. At this time, the thickness of the interior green sheet was 4.0 μm. An internal electrode paste and an electrode step absorption printing paste were printed thereon, and then the sheet was peeled from the PET film. Subsequently, these interior green sheets were laminated on the exterior green sheet. The number of laminated interior green sheets was 300. Then, a laminate was obtained by further laminating 30 layers of exterior green sheets.

  Next, the laminate was cut into a predetermined size to obtain a green chip, and then a binder removal process, firing and annealing were performed to obtain a capacitor element body.

  The binder removal treatment was performed under conditions of a temperature rising time of 15 ° C./hour, a holding temperature of 280 ° C., a holding time of 2 hours, and an air atmosphere.

Firing is performed in a temperature rising rate of 200 ° C./hour, a holding temperature of 1260 to 1340 ° C., a holding time of 2 hours, a cooling rate of 300 ° C./hour, and a humidified N ₂ + H ₂ mixed gas atmosphere (oxygen partial pressure is 10 ⁻⁶ Pa). Performed under conditions.

  The annealing was performed under the conditions of a holding temperature of 1200 ° C., a temperature holding time of 2 hours, a cooling rate of 300 ° C./hour, and a nitrogen atmosphere. Note that a wetter with a water temperature of 35 ° C. was used for humidifying the atmospheric gas during the binder removal and firing.

  The size of the capacitor element body (hereinafter referred to as “capacitor sample”) obtained through the above steps is 3.2 mm × 1.6 mm × 1.6 mm, and the total of the exterior parts disposed at both ends of the interior part. The thickness of each was 0.1 mm, and the thickness of the interior part was 1.4 mm.

  For the capacitor sample, the crack generation rate, bending strength, and protrusion amount were measured by the following methods.

(Crack occurrence rate)
About each obtained capacitor | condenser sample, the baking base was grind | polished and the lamination | stacking state was observed visually and the presence or absence of the base crack was confirmed. The presence or absence of the substrate crack was confirmed for each 10000 samples. As a result of the appearance inspection, the crack occurrence rate was determined by calculating the ratio of the samples in which the base cracks were generated with respect to 10,000 samples. In this example, 10 ppm or less was set as a preferable range, and 0 ppm was set as a more preferable range.

(Folding strength)
The bending strength was measured as follows based on the three-point measurement method defined in JIS-R1601. First, a pair of jigs 54 provided with a step having a width W1 at a corner was placed at an interval of a width W2. And the capacitor | condenser sample 52 was set | placed on the step part of the jig | tool 54 so that an exterior part might become an upper part as shown in FIG. Thereafter, the capacitor sample 52 was pressurized at a speed of 30 mm / min with a load 56 having a width of 2.0 mm and a curvature radius of the bottom surface of 0.5 mm, and the load pressure at the time of breaking was determined. In this example, 245N or more was set as a preferable range, and 315N or more was set as a more preferable range.

(Projection amount δ)
With respect to the obtained capacitor sample, as shown in FIG. 6, the width from the end of the exterior part to the end of the interior part in the direction perpendicular to the stacking direction was measured, and this was defined as the protrusion amount δ. The unit is μm. In this example, 7 μm or less was set as a preferable range, and 4 μm or less was set as a more preferable range.

Samples 2-7
A capacitor sample was prepared in the same manner as Sample 1 except that D50 of the second ceramic particles contained in the exterior dielectric layer paste was changed, and the crack generation rate, bending strength, and protrusion amount were obtained. The results are shown in Table 1.

Sample 8
A capacitor sample was prepared in the same manner as Sample 4 except that 30 parts by weight of the second ceramic particles were included in the internal electrode pattern layer with respect to 100 parts by weight of the Ni particles, and the crack generation rate, bending strength and protrusion amount were obtained. It was. The results are shown in Table 1.

Samples 1a-7a
D50 prepared 1a ceramic particles and second ceramic particles made of the main component raw material without containing the subcomponents described in Samples 1a to 7a, wet pulverized in a ball mill for 15 hours, dried, and Samples except that 4.8 parts by weight of acrylic resin, 100 parts by weight of ethyl acetate, 6 parts by weight of mineral spirit, and 4 parts by weight of toluene were mixed with a ball mill to obtain a paste for an exterior dielectric layer. Sample 1a is sample 1, Sample 2a is sample 2, Sample 3a is sample 3, Sample 4a is sample 4, Sample 5a is sample 5, Sample 6a is sample 6, Sample 7a is similar to sample 7, and a capacitor sample is prepared. Crack generation rate, bending strength, and protrusion amount were determined. The results are shown in Table 2.

Samples 11-17
Create capacitor samples except for changing the D50 of the first ceramic particles contained in the outer dielectric layer paste in the same manner as Sample 1, was determined crack incidence and bending strength. The results are shown in Table 3.

Samples 21-27
A capacitor sample was prepared in the same manner as Sample 4 except that the content of the first ceramic particles contained in the exterior dielectric layer paste was changed to 1 part by weight of the second ceramic particles contained in the exterior dielectric layer paste. The crack occurrence rate and the bending strength were determined. The results are shown in Table 4.

Samples 31-37
The content of the first ceramic particles contained in the exterior dielectric layer paste with respect to 1 part by weight of the second ceramic particles contained in the exterior dielectric layer paste is changed, and the particle diameter of the first ceramic particles is 0.62 μm, d _α. / except that d _beta of 1.77 creates a capacitor samples in the same manner as sample 1, was determined crack incidence and bending strength. The results are shown in Table 5.

Samples 1-7
From Samples 1 to 7, when d _α / d _β is included in the range of 1.2 ≦ d _α / d _β ≦ 3.0, the crack generation rate is 10 ppm or less, and the element body strength is 0.7 or more. (Samples 2 to 6). Further, when d _α / d _β was larger than 3.0, the crack occurrence rate was 100 ppm, and it was confirmed that the effect of crack suppression was small (Sample 1). Further, if the _d α _/ d β is in the range from _{1.5 ≦ d α / d β ≦} 1.8 , it was confirmed that the possible cracking incidence in 0 ppm (Sample 4, 5).

Samples 4 and 8
From Sample 4 and Sample 8, it was confirmed that the bending strength and the protrusion amount were improved by adding the second ceramic particles to the internal electrode paste.

Samples 1-7, Samples 1a-7a
It was confirmed that Samples 1 to 7 had better protrusion amounts than Samples 1a to 7a (FIG. 7). This is because, in Samples 1 to 7, the secondary component of the dielectric particles contained in the first ceramic particles played the role of a sintering aid, so that the sintering of the exterior portion was promoted. This is considered to be due to the suppression of the sinterability shift.

Samples 11-17
From samples 11 to 17, also d _alpha / d _beta is included in the range of _{1.2 ≦ d α / d β ≦} 3.0, when d _alpha is 0.35μm smaller (Sample 11), It was confirmed that the crack generation rate was increased to 80 ppm and the crack generation rate was increased even when d _α was larger than 0.5 μm (Samples 16 and 17).

Samples 21-27, Samples 31-37
From samples 21 to 27 and samples 31 to 37, it was confirmed that the crack generation rate is improved in the case where _W α _/ W β is in the range from _{4 ≦ W α / W β ≦} 9.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element main body 2a ... Interior dielectric layer 2b ... Exterior dielectric layer 3 ... Internal electrode layer 4 ... External electrode 20a ... Interior part 20b ... Exterior part 32a, 32b ... Main component 34a ... Subcomponent 36 ... 1st ceramic particle 38 ... 2nd ceramic particle 40 ... Support sheet 41 ... Press jig 42a ... Interior green sheet 43 ... Internal electrode pattern layer 44 ... Blank pattern part 45 ... Blank pattern layer 410 ... Laminate 52 ... Capacitor sample 54 ... Jig 56 ... Load

Claims (7)

An interior dielectric layer formed using an interior green sheet and an internal electrode layer formed using an internal electrode pattern layer are alternately stacked to obtain an interior portion, and formed using an exterior green sheet. Laminating at least one exterior dielectric layer on the interior part to obtain a green chip;
A step of obtaining an element body by firing the green chip, and a method of manufacturing an electronic component comprising:
The exterior green sheet includes first ceramic particles and second ceramic particles,
The first ceramic particles include a main component of a dielectric material contained in the interior green sheet and a subcomponent of a dielectric material contained in the interior green sheet,
The second ceramic particles are composed of a main component of a dielectric material contained in the interior green sheet,
When the value of 50% of the cumulative distribution of the particle size of the first ceramic particles is d _α μm and the value of 50% of the cumulative distribution of the particle size of the second ceramic particles is d _β μm, d _α and d _β The relationship is 1.2 ≦ d _α / d _β ≦ 3.0,
When the second ceramic particles contained in the exterior green sheet is 1 part by weight, the content ratio of the first ceramic particles contained in the exterior green sheet is 4.0 parts by weight or more and 9.0 parts by weight or less. A method for manufacturing an electronic component.   The method of manufacturing an electronic component according to claim 1, wherein the internal electrode pattern layer includes the second ceramic particles. 3. The method of manufacturing an electronic component according to claim 1, wherein a particle diameter of the first ceramic particles is 0.35 ≦ d _α ≦ 0.50. The method for manufacturing an electronic component according to claim 1, wherein a relationship between d _α and d _β is 1.5 ≦ d _α / d _β ≦ 1.8.   5. The structure according to claim 1, wherein the first ceramic particles have a structure in which at least a part of a main component of the dielectric material contained in the interior green sheet is coated with a subcomponent of the dielectric material contained in the interior green sheet. A method for manufacturing the electronic component according to claim 1.   The first ceramic particles have a structure in which at least a part of a main component of a dielectric material contained in the interior green sheet and at least a part of a subcomponent of the dielectric material contained in the interior green sheet are in solid solution. Item 5. A method for producing an electronic component according to any one of Items 1 to 4.   The method of manufacturing an electronic component according to claim 1, wherein the electronic component is a multilayer ceramic capacitor.

Images