JP2010257937A - Conductive paste, method of manufacturing the same, and method of manufacturing electronic parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive paste in which excessive growth of grains due to reaction between common materials with each other and reaction between the common materials and dielectric particles which form a dielectric layer can be suppressed even when the common materials mixed in the conductive paste are pulverized one, the conductive paste being capable of providing electronic parts with high reliability and same quality. <P>SOLUTION: The conductive paste includes conductive powder, a solvent, a binder, and ceramic powder, and the ceramic powder includes dielectric powder having a perovskite structure which is coated with magnesium oxide, an oxide of alkaline earth metal excluding magnesium and an oxide of rare earth. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a conductive paste used for forming internal electrodes of a multilayer ceramic electronic component and a method for manufacturing the same. Moreover, this invention relates to the manufacturing method of an electronic component including the process of forming an internal electrode pattern layer using this electrically conductive paste.

  In recent years, electronic devices have been reduced in size and weight. Along with this, further miniaturization and higher capacity have been promoted in the multilayer ceramic electronic parts used in the electronic devices.

  The most effective method for reducing the size and increasing the capacity of a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component is to make both the internal electrode and the dielectric layer as thin as possible (thinning), and to Is laminated as much as possible (multilayering).

  The multilayer ceramic capacitor is a ceramic green sheet mainly composed of ceramic powder represented by barium titanate and the like and a binder as a main component, and a conductive paste for forming an internal electrode is printed in a predetermined pattern, and a plurality of these are laminated, It is manufactured by co-firing and sintering integrally, and finally forming an external electrode.

  As the conductive paste for forming the internal electrode, a paste obtained by dispersing conductive powder in an organic vehicle in which an organic binder is dissolved in a solvent is used. In addition, a ceramic powder having the same or similar composition as the ceramic powder constituting the dielectric layer is usually added to the conductive paste as a co-material. By adding the co-material, the continuity of the internal electrode formed by firing the conductive paste is improved, and the bonding strength with the dielectric layer is also improved.

  The continuity of the internal electrodes decreases as the added amount of the common material increases, and is also impaired by excessive sintering of the common material. For this reason, in order to further improve the continuity of the internal electrode, it is considered effective to reduce the addition amount of the common material and to suppress the excessive sintering.

  From this point of view, Patent Document 1 discloses that the surface of a ceramic powder used as a co-material is coated with at least one oxide selected from the group consisting of Si, Cr, Mn, Ti, and V.

JP 2007-128730 A

  In order to reduce the thickness of the internal electrode, it is required to make the co-material blended in the conductive paste fine. However, if the co-material is made finer, the sintering reaction tends to be promoted, which leads to excessive grain growth due to the reaction between the co-materials and the reaction between the dielectric particles forming the dielectric layer and the co-material. The continuity of the electrode is impaired. As a result, the reliability of the electronic component is reduced, the quality of the component is not constant, and the breakdown voltage varies, for example.

  The present invention has been made in view of the conventional techniques as described above, and even when the co-material mixed in the conductive paste is made into fine particles, the reaction between the co-materials and the formation of the dielectric layer are formed. An object of the present invention is to provide a conductive paste that can suppress excessive grain growth due to a reaction between dielectric particles and a common material, and that can manufacture an electronic component with high reliability and constant quality.

  The present inventors have found that the above problems can be solved by applying a special coating to the co-material mixed in the conductive paste, and have completed the present invention.

That is, this invention which solves the said subject contains the following matter as a summary.
(1) includes conductive powder, solvent, binder, and ceramic powder;
A conductive paste obtained by coating the dielectric powder having a perovskite structure with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide.

(2) The conductive paste according to (1), wherein the alkaline earth metal is barium.

(3) The ceramic powder is
For 100 mole parts of dielectric powder,
Magnesium oxide, an alkaline earth metal oxide other than magnesium, and a rare earth oxide are coated in a total amount of 0.5 to 6 mole parts, and magnesium oxide and an alkaline earth metal other than magnesium In a total of 1 mol part of the oxide and rare earth oxide,
0.1 to 0.8 mole part of magnesium oxide in terms of MgO,
0.1 to 0.8 mole parts of an oxide of an alkaline earth metal other than magnesium in terms of AEO (AE is an alkaline earth element),
The electrically conductive paste as described in (1) or (2) which contains rare earth oxide 0.1-0.8 mol part in conversion of REO (RE is rare earth elements).

(4) The conductive paste according to any one of (1) to (3), comprising 5 to 20 parts by weight of ceramic powder per 100 parts by weight of the total amount of the conductive paste.

(5) a step of mixing a magnesium compound, an alkaline earth metal compound other than magnesium, a gel compound containing a rare earth compound, and a dielectric powder having a perovskite structure;
Heat treating the mixture to obtain a ceramic powder in which the dielectric powder is coated with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide;
The manufacturing method of the electrically conductive paste including the process of mixing this ceramic powder electrically conductive powder, a solvent, a binder, and ceramic powder.

(6) A method for manufacturing a multilayer ceramic electronic component comprising a step of alternately stacking a plurality of ceramic green sheets containing ceramic powder and a binder and a predetermined pattern of internal electrode pattern layers to obtain a green ceramic laminate. ,
A method for producing a multilayer ceramic electronic component, comprising: forming the internal electrode pattern layer by applying the conductive paste according to any one of (1) to (4) on a ceramic green sheet.

(7) A multilayer ceramic electronic component obtained by the manufacturing method according to (6) above.

  According to the present invention, even when the co-material mixed in the conductive paste is made into fine particles, excessive grain growth is caused by the reaction between the co-materials and the reaction between the dielectric particles forming the dielectric layer and the co-material. Therefore, it is possible to provide a conductive paste that can manufacture electronic parts with high reliability and constant quality.

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

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

  The multilayer ceramic electronic component manufactured using the conductive paste of the present invention is not particularly limited, and examples thereof include a multilayer ceramic capacitor, a multilayer ceramic inductor, a multilayer ceramic LC component, and a multilayer ceramic substrate.

  The present invention will be described based on embodiments shown in the drawings. FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

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

Multilayer Ceramic Capacitor As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention includes a capacitor body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. A pair of external electrodes 4 respectively connected to the internal electrode layers 3 alternately arranged inside the element body 10 are formed at both end portions of the capacitor element body 10. The internal electrode layers 3 are laminated so that the side end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor body 10. The pair of external electrodes 4 are formed at both ends of the capacitor body 10 and connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

  The outer shape and dimensions of the capacitor body 10 are not particularly limited and can be appropriately set depending on the application. Usually, the outer shape is substantially a rectangular parallelepiped shape, and the dimensions are usually vertical (0.4 to 5.6 mm) × It can be about horizontal (0.2-5.0 mm) × height (0.2-1.9 mm).

  The dielectric layer 2 is formed by firing a ceramic green sheet, and the material thereof is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. In the present embodiment, the thickness of the dielectric layer 2 is preferably reduced to 1 μm or less.

  The internal electrode layer 3 is formed by firing a predetermined pattern of internal electrode pattern layer made of the conductive paste of the present invention. In this embodiment, the thickness of the internal electrode layer 3 is preferably 1 μm or less.

  As the material of the external electrode 4, copper, a copper alloy, nickel, a nickel alloy, or the like is usually used, but silver, a silver-palladium alloy, or the like can also be used. The thickness of the external electrode 4 is not particularly limited, but is usually about 10 to 50 μm.

The conductive paste internal electrode layer 3 is formed from the conductive paste of the present invention. The conductive paste includes conductive powder, a solvent, a binder, and ceramic powder.

Conductive powder The conductor powder contained in the conductive paste is not particularly limited, but is preferably composed of at least one selected from Cu, Ni and alloys thereof, more preferably Ni. Or it is comprised with Ni alloy and also a mixture thereof.

  Such a conductor powder is not particularly limited in its shape, such as a spherical shape or a flake shape, and may be a mixture of these shapes. The conductor powder preferably has a D50 diameter of 0.5 μm or less, more preferably 0.1 to 0.2 μm, as measured by SEM. As a result, it is possible to reliably realize a thin layer.

Solvent solvent is not particularly limited, and α-terpinyl acetate, isobornyl acetate, isobornyl propionate, isobornyl butyrate, isobornyl isobutyrate, dihydroterpinyl acetate, dihydroterpinyl methyl ether, Organic solvents such as pinyl methyl ether, l-dihydrocarbyl acetate, terpineol, butyl carbitol, acetone and toluene are used. Moreover, when using a water-soluble binder, water can also be used.

The binder binder is not particularly limited, and various ordinary binders such as ethyl cellulose, polyvinyl butyral, and acrylic resin are used, but a butyral resin such as polyvinyl butyral is preferably used. As the water-soluble binder, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, a water-soluble acrylic resin, an emulsion, or the like is used.

Ceramic powder The ceramic powder used as a co-material in the present invention is a composite powder obtained by coating a dielectric powder having a perovskite structure with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide. It is.

  The dielectric powder preferably has the same or similar composition as the ceramic constituting the dielectric layer. Since the conductive paste has the co-material, the difference in shrinkage ratio during firing between the conductor powder contained in the internal electrode pattern layer and the ceramic powder contained in the green sheet can be reduced. . As a result, generation of cracks in the sintered body can be suppressed.

Dielectric powder is not particularly limited, for _{example, {(Ba (1-x} -y) Ca x Sr y) O} A (Ti (1-z) Zr z) dielectric oxide expressed by B _{O 2} Examples thereof include powders mainly composed of products. Note that A, B, x, y, and z are all in an arbitrary range. As subcomponents included together with the main component in the dielectric oxide, Sr, Y, Gd, Tb, Dy, V, Mo, Ho, Yb, Zn, Cd, Ti, Sn, W, Ba, Ca, Mg, Examples of subcomponents include one or more selected from Cr and P oxides. In addition, in this invention, when Si and Mn are contained as a subcomponent of the dielectric powder constituting the common material, or when Si and Mn are contained in the coating layer described later, the required effect may not be achieved. is there.

The surface of the dielectric powder is composed of magnesium oxide (MgO), an oxide of an alkaline earth metal other than magnesium (AeO (Ae is an alkaline earth element)), and a rare earth oxide (Re ₂ O ₃ (Re is a rare earth element). Element)).

Examples of the alkaline earth metal oxide other than magnesium include CaO, SrO, and BaO. These may be used alone or in combination of two or more. Particularly when the dielectric powder is BaTiO ₃ is, BaO is preferably used. When CaO or SrO is used, Ca or Sr may be substituted at the Ti site of BaTiO ₃ during sintering, and the A / B ratio may be lowered in the ABO ₃ crystal structure. When the A / B ratio is lowered, grain growth is likely to occur during sintering, and the continuity of the internal electrode layer may be lowered.

The rare earth oxide (Re ₂ O ₃ ) is not particularly limited and may be oxides of various rare earth elements, but preferably Y, Eu, Gd, Tb, Dy, Ho, Er, Tm or It is preferably at least one oxide of each element of Yb, more preferably an oxide of Y, Gd, Dy, Er, or Ho. These rare earth elements may be used alone or in combination, and the same effect can be obtained.

The coating layer in the ceramic powder is based on 100 mol parts of the dielectric powder.
The total amount of magnesium oxide, an alkaline earth metal oxide other than magnesium, and the rare earth oxide is preferably 0.5 to 6 mol parts, preferably 1 to 5 mol parts, more preferably 2 to 4 mol parts. It is coated with an amount. If the amount of oxide forming the coating layer is too small, excessive grain growth due to the reaction between the co-materials and the reaction between the dielectric particles forming the dielectric layer and the co-materials cannot be suppressed. Since the continuity is lowered, the reliability of the electronic component is lowered and the quality is varied. On the other hand, if the amount of oxide forming the coating layer is too large, there is a risk that the sintering of the dielectric will be inhibited or the continuity of the internal electrodes will be lost, and the characteristics will not be satisfied.

In addition, when the total of magnesium oxide, alkaline earth metal oxide other than magnesium, and rare earth oxide included in the coating layer is 1 mol part, the coating layer is
Magnesium oxide in terms of MgO is preferably 0.1 to 0.8 mole part, more preferably 0.2 to 0.6 mole part, particularly preferably 0.4 to 0.6 mole part,
Preferably, the oxide of an alkaline earth metal other than magnesium is 0.1 to 0.8 mol part, more preferably 0.1 to 0.5 mol part, particularly preferably in terms of AeO (Ae is an alkaline earth element). 0.2-0.4 mol part,
The rare earth oxide is preferably 0.1 to 0.8 mol part, more preferably 0.1 to 0.5 mol part, particularly preferably 0.2 to 0.00 mol part in terms of Re ₂ O ₃ (Re is a rare earth element). It is contained in an amount of 4 mol parts.

  If the composition of the coating layer is out of the above range, sufficient continuity cannot be obtained for the sintered internal electrode, or sufficient reliability as a multilayer capacitor may not be obtained.

  It is desirable that the ceramic powder has the same shape and particle size as possible. The particle size of the ceramic powder is preferably from 0.01 μm to 1,000 μm when the diameter observed and measured by SEM is expressed as an average particle size (D50). It is in the range of 0.1 μm, more preferably 0.02 to 0.06 μm.

The ceramic powder can be obtained by mixing a gel compound and a dielectric powder and heat-treating the mixture. The gel compound contains a magnesium compound, an alkaline earth metal compound other than magnesium, and a gel compound containing a rare earth compound. When a gel hydroxide is used as the gel compound, for example, it is obtained by dissolving a metal carbonate with an acid and reacting it with ammonia. For example, a gel-like material containing magnesium hydroxide can be obtained by dissolving magnesium carbonate with acetic acid, citric acid or the like and reacting with ammonia. Other metal gel hydroxides can be obtained in the same manner.
When carbonate is used as the gel compound, for example, a metal carbonate is dissolved with an acid and reacted by blowing ammonium bicarbonate or carbon dioxide gas. The same applies when obtaining gelled magnesium carbonate.
When gelling magnesium, it is most preferable to gel in the form of hydroxide from the viewpoint of obtaining a uniform gel.
When gelling with Ba or Ca as an alkaline earth metal other than magnesium, some may become carbonate if gelled in the form of hydroxide, which may be slightly unstable chemically. is there. For this reason, Ba and Ca are preferably gelled in the form of carbonate.

When coating a dielectric compound having a relatively small particle size (for example, BaTiO ₃ ), if a gel-like compound composed of relatively large particles (for example, a particle size equivalent to the above-described dielectric particle) is used, uniformly coat it. Is difficult. Therefore, in order to uniformly coat each additive, it is desirable that the additive in the gel solution is dispersed in smaller particles. Specifically, the specific surface area, 100 m ² / g or more measured by the BET method, ^preferably, it is preferable to use a gel-like compound is 200m ² / g~400m 2 / g. Thus, by using a sufficiently fine gel-like compound, there is almost no difference in the coating state depending on the composition, and a sufficient coating state can be obtained.

  In addition, each composition is desirably an optimum composition for the target characteristics, and the optimum composition varies depending on the composition of the dielectric.

  After mixing the dielectric powder and the gel compound with a bead mill, the slurry is taken out into a vat, dried at 120 ° C. with a hot air circulating dryer, crushed aggregated particles, and the powder is put into a crucible, 400 to 800 A ceramic powder in which the dielectric powder is coated with a metal oxide is obtained by heat treatment at 1 ° C. for 1 to 3 hours. (For drying, for example, freeze-drying or the like may be used as a drying method for preventing agglomeration of the powder.)

  Moreover, ceramic powder can also be obtained by hydrolyzing a metal alkoxide in the presence of a dielectric powder and then heat-treating in the same manner.

Other ingredients conductive paste, in addition to the above components, may contain a tackifier other than the. As the tackifier, gum rosin, polymerized rosin, terpene phenol, alicyclic petroleum resin, rosin glycerin ester and the like are used.

The blending ratio of the conductive powder, the solvent, the binder, and the ceramic powder in the blending ratio conductive paste is not particularly limited, but it is good by designing these contents and addition ratios within an appropriate range. Handling property, sheet drying property, binder removal property, and adhesion of the laminate can be maintained. A preferred blending ratio is shown below.

  The content of the conductor powder in the conductive paste is preferably 30 to 60% by weight, more preferably 40 to 55% by weight. When there are too many conductor powders, it is difficult to make a paint and the coating property of the paste is lowered. On the other hand, when there is too little conductor powder, there exists a possibility that the internal electrode after baking may disconnect.

  The content of the solvent is preferably 0.2 to 13.5 parts by weight, preferably 0.5 to 9 parts by weight with respect to 100 parts by weight of the conductive powder. When the amount of the solvent is too large, the drying property of the printed sheet may be deteriorated. On the other hand, when the amount is too small, the adhesive force is insufficient, and the laminate may be defective such as poor lamination.

  The content of the binder is preferably 1 to 8.5 parts by weight, preferably 1 to 6 parts by weight with respect to 100 parts by weight of the conductive powder. When there is too much binder, the binder removal property is deteriorated, which may cause internal structural defects such as cracks and delamination, while when it is too small, the paste viscosity is low and printability may be deteriorated. is there.

  The ceramic powder used as the co-material is preferably contained in the conductive paste in an amount of 5 to 20% by weight, more preferably 7 to 16% by weight. If the amount of the co-material is too small, the sintering suppression effect of the conductive powder is lowered, the lineability (continuity) of the internal electrode layer 3 after firing is deteriorated, and the pressure resistance is lowered. On the other hand, when there is too much amount of co-materials, the line property of the internal electrode layer 3 after baking becomes easy to deteriorate, and the device physical properties also tend to deteriorate.

  Moreover, when mix | blending a tackifier, the content becomes like this. Preferably it is 0.1-4.5 weight part with respect to 100 weight part of electroconductive powder, Preferably it is 0.5-4.0 weight part. . When the tackifier is too much, the paste viscosity is low and the printability may be deteriorated. On the other hand, when the amount is too small, the adhesive force is insufficient, and a laminate failure such as poor lamination may occur frequently.

  The conductive paste can be obtained by kneading the above components with a ball mill or the like and forming a slurry into a paste with a three-roll mill or the like.

Method for Manufacturing Multilayer Ceramic Capacitor Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 according to this embodiment will be described.
Preparation of Dielectric Paste (1) First, a dielectric paste is prepared in order to manufacture a ceramic green sheet that will constitute the dielectric layer 2 shown in FIG. 1 after firing.

  In this embodiment, the dielectric paste is composed of an organic solvent-based paste obtained by kneading a raw material powder serving as a dielectric and an organic vehicle.

  The raw material powder to be a dielectric is appropriately selected from various compounds to be complex oxides and oxides, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, and can be used by mixing them. The raw material powder is usually used as a powder having an average particle size of 2.0 μm or less, preferably about 0.1 to 0.8 μm. In order to form a very thin ceramic green sheet, it is desirable to use a powder finer than the thickness of the ceramic green sheet.

  As the organic binder used in the organic vehicle, butyral resin, acrylic resin, or the like is used. The organic binder is preferably contained in an amount of more than 5 parts by weight and less than 10 parts by weight, more preferably 6 to 9 parts by weight with respect to 100 parts by weight of the raw material powder. If the content of the organic binder is too small, the sheet lamination property (stackability) tends to be deteriorated, and if it is too much, it is not completely removed in the binder removal step, and there is a tendency that many cracks are generated in the sintered body. .

  The organic solvent used for the organic vehicle is not particularly limited, and methyl ethyl ketone, butyl carbitol, acetone, toluene and the like are used.

  Content of each component in a dielectric paste is not specifically limited, For example, a dielectric paste can be prepared so that 1-50 weight% of solvent may be included.

  The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, subcomponent compounds, glass frit, insulators, and the like, if necessary. When these additives are added to the dielectric paste, the total content is desirably about 10% by weight or less.

  Examples of the plasticizer include phthalate esters such as dioctyl phthalate and benzylbutyl phthalate, adipic acid, phosphate esters, glycols, and the like. The weight ratio of the plasticizer in the paint when blending the plasticizer is not particularly limited, but is preferably 40 to 70 parts by weight with respect to 100 parts by weight of the binder. If the amount of the plasticizer is too small, the elongation and flexibility of the green sheet tend to be deteriorated. If the amount is too large, the plasticizer oozes out on the surface of the green sheet and is difficult to handle.

  The dielectric paste can be obtained by kneading the above components with a ball mill or the like to form a slurry.

Formation of Ceramic Green Sheet (2) Next, using this dielectric paste, a ceramic green sheet is preferably formed with a thickness of about 1 μm or less on a carrier sheet as a support by a doctor blade method or the like.

  As the carrier sheet, for example, a PET film is used, and in order to improve the peelability, a surface on which the ceramic green sheet is formed is preferably subjected to a release treatment (coating such as silicone). Although the thickness of a carrier sheet is not specifically limited, Preferably it is 5-100 micrometers.

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

  The thickness of the ceramic green sheet after drying contracts by 5 to 25% from the thickness before drying. In the present embodiment, the thickness of the dried ceramic green sheet is preferably 0.4 to 1.5 μm, more preferably 0.4 to 1.2 μm, and particularly preferably 0.4 to 0.8 μm. Form. This is in order to meet the demand for thinner layers in recent years. If the thickness of the green sheet is too thick, the binder resin content per layer increases depending on the thickness of the internal electrode pattern layer, and internal structural defects such as cracks tend to occur after firing.

Preparation of Conductive Paste (3) Next, in order to form an internal electrode pattern layer that will form the internal electrode layer 3 shown in FIG. 1 after firing on the surface of the ceramic green sheet, the conductive paste of the present invention is used. Prepare a sex paste. As described above, the conductive paste of the present invention is obtained by kneading a conductive powder, a solvent, a binder, and a ceramic powder with a ball mill or the like to form a slurry.

Formation of Internal Electrode Pattern Layer (4) Next, an internal electrode pattern layer having a predetermined pattern is formed on the surface of the ceramic green sheet formed on the carrier sheet using a conductive paste.

  The method for forming the internal electrode pattern layer is not particularly limited as long as the layer can be formed uniformly, but in this embodiment, the screen printing method using the above-described conductive paste is used.

  The thickness of the internal electrode pattern layer is preferably 0.4 to 1 μm. If the internal electrode pattern layer is too thick, depending on the thickness of the green sheet, the binder resin content per layer increases, and cracks tend to occur after firing. Furthermore, the number of stacked layers must be reduced, and the acquired capacity is reduced, making it difficult to increase the capacity. On the other hand, if the thickness is too thin, it is difficult to form uniformly, and electrode breakage is likely to occur.

  The thickness of the internal electrode pattern layer is about the above-mentioned range in the current technology, but it is more desirable that the thickness of the internal electrode pattern layer is as small as possible in the range in which the electrode is not broken.

  Thereafter, the internal electrode pattern layer is dried as necessary. The drying temperature is not particularly limited, but is preferably 50 to 120 ° C., and the drying time is preferably 1 to 15 minutes.

Formation of Blank Pattern Layer (5) In this embodiment, after the internal electrode pattern layer having a predetermined pattern is formed on the surface of the ceramic green sheet by the printing method, or before the internal electrode pattern layer is formed on the ceramic A blank pattern layer having substantially the same thickness as the internal electrode pattern layer is formed in the surface gap (blank pattern portion) of the green sheet. The reason why the thickness of the blank pattern layer is set to be substantially the same as that of the internal electrode pattern layer is that a step is formed unless the thickness is substantially the same, and the influence increases particularly when the number of layers is increased.

  In the present embodiment, the blank pattern layer is formed by a screen printing method using an electrode level difference absorbing printing paste. The electrode level difference absorbing printing paste is not particularly limited, but the dielectric paste prepared above is preferably used in the process.

  Thereafter, the internal electrode pattern layer and / or the blank pattern layer are dried as necessary. The drying temperature is not particularly limited, but is preferably 50 to 120 ° C., and the drying time is preferably 1 to 15 minutes. Thereafter, a plurality of ceramic green sheets on which internal electrode pattern layers and / or blank pattern layers are formed are laminated.

Formation of outer layer (6) In this embodiment, an outer layer is formed in order to protect the ceramic green sheet on which the internal electrode pattern layer and the blank pattern layer having the predetermined pattern formed above are formed. That is, a predetermined number of laminated ceramic green sheets are sandwiched between outer layers. The outer layer has a structure in which one or more ceramic green sheets on which no internal electrode pattern layer is formed are laminated.

  Similar to the ceramic green sheet, the outer layer green sheet is formed on the carrier sheet using the outer layer dielectric paste. As the dielectric paste for the outer layer, the dielectric paste produced as described above may be used. However, a paste in which the binder type, the amount of binder added, the degree of binder polymerization, and the like are changed may be used.

Lamination process (7) Next, the ceramic green laminated body in which the green sheet for outer layers was formed is peeled from a carrier sheet, and this green ceramic laminated body is press-pressed after that. The pressing temperature is preferably 50 to 100 ° C., and the applied pressure is preferably 3 to 25 MPa. If the applied pressure is too large, the laminate is deformed, causing internal structural defects such as cracks. If the applied pressure is too low, the adhesive strength of the laminate is reduced, making it difficult to obtain a good laminate.

Green chip production, firing, etc. (8) The obtained green ceramic laminate was cut into a predetermined size to produce a green chip, which was formed through a binder removal process, a firing process, and an annealing process performed as necessary. Then, the external electrode paste is printed or transferred to the capacitor body 10 made of a sintered body and fired to form the external electrode 4, whereby the multilayer ceramic capacitor 1 is manufactured.

  Even if the co-material blended in the conductive paste is made into fine particles by the method described in the present embodiment, the reaction between the co-materials and the reaction between the dielectric particles forming the dielectric layer and the co-materials. An excessive grain growth can be suppressed, and an electronic component with high reliability and constant quality can be manufactured.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor and can be applied to a multilayer ceramic substrate or the like. It is.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples. The evaluation items in the following examples and comparative examples were measured as follows.

(High temperature load life)
The capacitor sample was held at 160 ° C. with a DC voltage of 9 V / μm, and the high temperature load life was measured. This high temperature load life was evaluated by measuring 10 life samples and measuring the average life time. As an evaluation, the time from the start of application until the resistance dropped by an order of magnitude was defined as the lifetime. The longer the lifetime is, the better. In this embodiment, the lifetime is preferably 20 hours or longer, more preferably 30 hours or longer.

(CR product)
The insulation resistance IR after applying a DC voltage of 5 V / μm to the capacitor sample for 1 minute at 20 ° C. was measured using an insulation resistance meter (advantest R8340A). The CR product was measured by determining the product of the capacitance C (unit: μF) measured above and the insulation resistance IR (unit: MΩ). In this example, 500 MΩ · F or more was considered good. More preferably, it is 1000 MΩ · F or more.

(Withstand voltage)
A withstand voltage was defined as a voltage at which a current of 10 mA or more was applied to the capacitor sample when a voltage was applied. The number of measurements was 50 for each composition, and the central value was the representative value. The withstand voltage is preferably higher. In this embodiment, it is preferably 50 V or more, more preferably 100 V or more.

(Crack occurrence rate)
The crack generation rate was evaluated as follows.
All capacitors were inspected for appearance. The number of measurements was 100. As a result, 0% was considered good.

(Ni coverage)
Ni coverage ratio is the ratio of the length and the total length excluding the discontinuous portion of the internal electrode by polishing the cross section of the element body after firing, observing and measuring the total length of the Ni internal electrode and the length of the disconnected portion with a laser microscope Was expressed as Ni internal electrode continuity. The Ni coverage is preferably 75% or more. If the Ni coverage is less than 75%, it may be impossible to obtain a desired capacity or cause a variation in capacity.

(C value variation)
A value of (σ / X) × 100 (%) was obtained from the average value X of the obtained capacitance values and the value of the standard deviation σ, and used as an index of capacitance variation (C value variation). The smaller the variation in capacitance, the better. In this example, 3% or less was judged good.

(Examples and Comparative Examples)
Production of dielectric paste
First, a dielectric paste for forming a ceramic green sheet was produced. Preparation of BaTiO ₃ ceramic powder, polyvinyl butyral resin (PVB) (polymerization degree: 800) as an organic binder, propyl alcohol, xylene, methyl ethyl ketone, 2-butoxyethyl alcohol as a solvent, and dioctyl phthalate as a plasticizer did. Next, 6 parts by weight of PVB, 150 parts by weight of solvent, and plasticizer are weighed with respect to 100 parts by weight of ceramic powder, and kneaded with a zirconia ball having a diameter of 2 mm in a ball mill for 21 hours to form a slurry and dielectric A body paste was obtained. The plasticizer was added in an amount of 50 parts by weight with respect to 100 parts by weight of polyvinyl butyral.

Production of conductive paste ( production of ceramic powder)
First, a gel compound containing an Mg compound, an alkaline earth metal compound other than Mg, and a rare earth compound was prepared.

In this embodiment, a gel hydroxide of Mg and rare earth was prepared, and a gel carbonate was prepared for an alkaline earth metal other than Mg.
The gel hydroxide is obtained by dissolving a metal carbonate with an acid and reacting with ammonia or the like. For example, a gel containing magnesium hydroxide is obtained by dissolving magnesium carbonate with acetic acid and reacting with ammonia. Other metal gel hydroxides can be obtained in the same manner.
When carbonate is used as the gel compound, for example, a metal carbonate is dissolved with an acid and reacted by blowing ammonium bicarbonate or carbon dioxide gas. The same applies when obtaining gelled magnesium carbonate.

  About Mn and Si, the oxide powder was used for comparative examination (Sample 16).

  Dielectric powder is prepared so that the weight ratio with respect to the dielectric powder and the ratio of each compound gel (oxide conversion) to the total amount of gel compounds (oxide conversion) are the ratios shown in Table 1. And the gel compound are mixed in a bead mill, the slurry is taken out into a vat, dried at 120 ° C. with a hot air circulating dryer, the aggregated particles are crushed, the powder is put into a crucible, and the mixture is put at 400 to 800 ° C. By performing the heat treatment for 3 hours, a ceramic powder in which the dielectric powder is coated with a metal oxide can be obtained. (For drying, for example, freeze-drying or the like may be used as a drying method for preventing agglomeration of the powder.)

In Sample 16, a film containing Si and Mn oxides in addition to the above was formed. In Sample 17 (Comparative Example), the above dielectric powder and MgO, BaO, Y ₂ O ₃ powder were mixed at a blending ratio shown in Table 1 to obtain a ceramic powder.

(Preparation of conductive paste)
Next, a conductive paste was produced using the ceramic powder as described below. 50% by weight of Ni particles having a specific surface area equivalent particle size of 0.2 μm as conductive powder, 40% by weight of terpineol as a solvent, 1.5% by weight of ethyl cellulose as a binder, and 15% by weight of the ceramic powder. Each component was mixed, kneaded with three rolls, and slurried to obtain a conductive paste.
Further, in Samples 18 to 23, the ceramic powder prepared in Sample 3 was used, and the amount of ceramic powder added was changed as shown in Table 2 to obtain a conductive paste.

Production of Multilayer Ceramic Chip Capacitor Sample Next, using the dielectric paste produced above and a conductive paste, a multilayer ceramic chip capacitor 1 shown in FIG. 1 was further produced as follows.

  First, a dielectric sheet was applied with a predetermined thickness on a surface of a PET film as a support subjected to a release treatment using a wire bar coater, and dried to prepare a green sheet.

  Next, a pattern was formed on the obtained green sheet by a screen printing method using a conductive paste, and dried at 85 ° C. to 95 ° C. for 1 to 2 minutes to form an internal electrode pattern layer.

  Thereafter, a blank pattern layer having substantially the same thickness as the internal electrode pattern layer is formed by screen printing using a dielectric paste on the blank pattern portion on the green sheet where the internal electrode pattern layer is not formed. A ceramic green sheet having a pattern film and a blank pattern layer was obtained. In this example, a plurality of ceramic green sheets were prepared.

  Next, a dielectric paste for forming an outer layer green sheet was prepared in the same manner as the dielectric paste prepared above. This dielectric paste was applied on the surface of the PET film that had been subjected to the release treatment using a wire bar coater with a predetermined thickness, and dried to produce an outer layer green sheet.

  A plurality of the outer layer green sheets were laminated by thermocompression bonding to form an outer layer. A ceramic green sheet on which an internal electrode pattern layer and a blank pattern layer were formed was laminated on the obtained outer layer, and the PET film was peeled off. This process was repeated to laminate a desired number of ceramic green sheets on which the internal electrode pattern layer and the blank pattern layer were formed. Thereafter, the above outer layer was further formed to obtain a green ceramic laminate. Next, the green ceramic laminate was press-bonded under conditions of a temperature of 80 ° C. and a pressure of 40 MPa.

  When laminating the ceramic green sheet on which the internal electrode pattern layer and the blank pattern layer are formed, the internal electrode portion is shifted by half in the longitudinal direction of the strip shape with respect to the ceramic green sheet laminated immediately before, and the short side In the direction, positioning was performed accurately so that each electrode portion overlapped.

  Next, after the obtained green ceramic laminate was cut into a predetermined size, binder removal, firing and annealing were performed under the following conditions to obtain a sintered body.

  The binder removal was performed under the conditions of a temperature rising rate: 15 ° C./hour, a holding temperature: 280 ° C., a holding time: 8 hours, and a processing atmosphere: an air atmosphere.

Firing is performed at a heating rate of 200 ° C./hour, a holding temperature of 1200 to 1380 ° C., a holding time of 2 hours, a cooling rate of 300 ° C./hour, a processing atmosphere: a reducing atmosphere (oxygen partial pressure: 10 ⁻⁶ Pa to N The mixed gas of ₂ and H ₂ was adjusted by passing water vapor).

The annealing was performed under the conditions of a holding temperature: 900 ° C., a holding time: 9 hours, a cooling rate: 300 ° C./hour, and a processing atmosphere: a humidified N ₂ gas atmosphere. A wetter was used to wet the gas during firing and annealing, and the water temperature was set to 35 ° C.

  Said evaluation was performed about the obtained ceramic sintered compact. The results are shown in Tables 1 to 3.

  As described above, by using a ceramic powder obtained by coating a dielectric powder having a perovskite structure with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide, the withstand voltage is reduced. A multilayer ceramic capacitor of 50 V or higher was obtained.

  Further, as shown in Samples 2 to 4, Mg, Ba, and Y are converted into oxides in a total of 1 mol part of MgO, an oxide of an alkaline earth metal other than Mg, and a rare earth oxide, respectively. By being contained in the range of 0.1 to 0.8 mol part, the high temperature load life, withstand voltage, and CR product are improved. Samples 5, 7, and 9 also contained MgO, Ba, and Y in terms of oxides in a total of 1 mole part of MgO, an oxide of an alkaline earth metal other than Mg, and a rare earth oxide. Although it is in the range of 0.8 mol part, the composition of Mg, Ba, and Y is uneven, so that the withstand voltage satisfies 50 V or more, but the high-temperature load life slightly decreases. In Samples 1, 6, and 8, any one of Mg, Ba, and Y was less than 0.1 mol part, so that the withstand voltage satisfied 50 V or more, but both the high-temperature load life and the CR product decreased.

  In Samples 10 and 11, the total amount of MgO, an alkaline earth metal oxide other than Mg, and a rare earth oxide is less than 0.5 mol part or 6 mol with respect to 100 mol parts of the dielectric powder. Therefore, the characteristic value is inferior to those of Samples 2 to 4.

  From Samples 12 to 15, when Sr or Ca is used as the alkaline earth metal instead of Ba, the case where the oxide of Dy or Ho is used as the rare earth oxide is good in characteristics. Recognize.

  From Sample 16, it was confirmed that when the gel compound of Mn and Si alkoxide were used in combination, the desired characteristics were not satisfied. In the case of simple addition as in Sample 17, the coating of dielectric particles became insufficient, and the high temperature load life was reduced.

  As shown in Samples 18 to 23, when the addition ratio of the ceramic powder in the conductive paste is less than 5% by weight, there is a problem that the crack generation rate increases. On the other hand, when it is larger than 20% by weight, the Ni coverage is lowered, and the variation in capacitance is increased.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor body 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode

Claims (7)

Including conductive powder, solvent, binder, ceramic powder,
A conductive paste obtained by coating the dielectric powder having a perovskite structure with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide.   The conductive paste according to claim 1, wherein the alkaline earth metal is barium. The ceramic powder is
For 100 mole parts of dielectric powder,
Magnesium oxide, an alkaline earth metal oxide other than magnesium, and a rare earth oxide are coated in a total amount of 0.5 to 6 mole parts, and magnesium oxide and an alkaline earth metal other than magnesium In a total of 1 mol part of the oxide and rare earth oxide,
0.1 to 0.8 mole part of magnesium oxide in terms of MgO,
0.1 to 0.8 mole part of an oxide of an alkaline earth metal other than magnesium in terms of AeO (Ae is an alkaline earth element),
Rare earth oxide _Re 2 _O 3 (Re is a rare earth element) converted at 0.1 to 0.8 molar parts containing claims 1 or 2 in the conductive paste according.   The electrically conductive paste in any one of Claims 1-3 which contain the said ceramic powder 5 to 20weight% in an electrically conductive paste. A step of mixing a magnesium compound, an alkaline earth metal compound other than magnesium, a gel compound containing a rare earth compound, and a dielectric powder having a perovskite structure;
Heat treating the mixture to obtain a ceramic powder in which the dielectric powder is coated with magnesium oxide, an oxide of an alkaline earth metal other than magnesium, and a rare earth oxide;
The manufacturing method of the electrically conductive paste including the process of mixing this ceramic powder electrically conductive powder, a solvent, a binder, and ceramic powder. A method for producing a multilayer ceramic electronic component comprising a step of alternately stacking a plurality of ceramic green sheets containing ceramic powder and a binder and an internal electrode pattern layer having a predetermined pattern to obtain a green ceramic laminate,
The manufacturing method of a multilayer ceramic electronic component including the process of apply | coating and forming the said electrically conductive paste in any one of Claims 1-4 on a ceramic green sheet.   A multilayer ceramic electronic component obtained by the manufacturing method according to claim 6.

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