JPH05291072A - Manufacture of multi-layered ceramic capacitor - Google Patents

Abstract

PURPOSE: To suppress the generation of cracks and delamination by heating a multi-layered laminate in a specific sintering-temperature profile and including an additive, in addition to fine particles of a conductive metal, in a conductor composition layer. CONSTITUTION: A multi-layered laminate of a dielectric composition layer and a conductor composition layer is heated at a first temperature. The laminate, after having been subjected to a first step is then heated to a second temperature which is higher than the first temperature at a rate of 450 deg.C/hr. Next, the laminate after having been subjected to a second step is heated at a third temperature which is higher than the second temperature. The conductor composition layer is made of a thin-film conductor composition layer containing fine particles of conductive metal and an additive. Thereby there is obtained a good quality of multi-layered ceramic capacitor, which can suppress the generation of cracking and delamination and further can shorten a sintering time over prior art.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer ceramic capacitor, and particularly to a temperature profile when firing a multilayer laminate of a dielectric composition layer and a conductor composition layer, and the conductor composition layer. Regarding composition.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor includes a metal conductor composition layer (electrode) formed by usually screen-printing a paste-like thick film conductor composition (electrode composition) and a ceramic oxide. A plurality of interpositions with a dielectric composition layer (dielectric) formed by casting a dielectric composition slurry on an electrode obtained by stacking or drying a green sheet composed of a dielectric composition as a main component, and It consists of staggered layers. Such capacitors are well known. For example, US Pat. No. 2,389,
No. 420 describes the structure, manufacture and properties of monolithic multilayer ceramic capacitors.

Usually, the electrode composition is palladium, silver,
It is a fine noble metal powder, such as gold, platinum or mixtures thereof, dispersed in a vehicle, which is usually alone organic. Dispersions of non-noble metals such as copper and nickel are also useful in electrode compositions. Generally, the vehicle will consist of a mixture of a polymeric resin that imparts viscosity to the composition and a suitable solvent, which provides processing compatibility, particularly with respect to dryness. In addition, organic additives are commonly added to the vehicle to control the rheology of the paste. The metal concentration of a typical electrode composition is in the range of 40-70% by weight with the balance being vehicle. The electrode composition is deposited on the dried dielectric composition layer, usually by screen printing techniques, and then dried to remove the solvent, leaving a mixture of metal powder and resin from the vehicle.

The dielectric composition layer is usually composed of fine oxide powder dispersed in a resin. Barium titanate (BaTiO ₃ ) and neodymium titanate (N
d ₂ Ti ₂ O ₇ ) and magnesium titanate (MgTiO 3
Oxides such as ₃ ) are used. Additives are commonly added to the above oxides to maximize various electrical properties, especially the dielectric constant, while controlling the temperature dependence of the dielectric constant and insulation resistance among other properties. In addition, a resin is present in the dielectric composition layer to facilitate handling and printing of the electrode on the dielectric composition layer.

In a multilayer ceramic capacitor, a conductor composition layer and a dielectric composition layer are stacked in an interposing arrangement, individual parts of the stacked product are diced, then these are slowly burned out (pre-baking), and then high temperature firing ( Main firing)
It is manufactured by The pre-baking is performed to remove the organic resin in the conductor composition layer and the dielectric composition layer (remove binder) to avoid rapid gas generation and partial destruction. The main calcination is performed at a peak temperature (dielectric thermal temperature). In this main firing, the chemical components of the dielectric are reacted so that the dielectric is densified so that the dielectric constant and physical strength of the dielectric are maximized and other desired electrical properties are obtained. During the main firing, the powder particles in the conductor composition layer are also sintered and densified to form a continuous metal film having high conductivity.

The main problem in the manufacture of multilayer ceramic capacitors arises from the simultaneous firing of the conductor composition layer and the dielectric composition layer. During the main firing, ordinary physical defects called cracks occur. When cracks occur, the resistance value increases and the insulation properties deteriorate, which adversely affects the performance of the finished multilayer ceramic capacitor. Therefore, cracking must be tightly controlled and preferably completely eliminated.

During the main firing of the capacitor, the conductor composition layer first expands and then begins to sinter and densify and contract. On the other hand, the dielectric composition layer densifies at a temperature higher than the densification temperature of the conductor composition layer and starts sintering shrinkage.
During the main firing of the capacitor, the expansion of the conductor composition layer is the main cause of cracking of the dielectric composition layer. The expansion and sintering shrinkage of the conductor composition layer also cause so-called delamination in which the conductor composition layer and the dielectric composition layer are separated from each other.

As a method for suppressing the occurrence of cracks during the main firing of a capacitor, for example, a method of firing in a nitrogen atmosphere or a low oxygen concentration atmosphere is known, but it is possible to control the sintering of the conductor composition layer. There are problems such as becoming very difficult.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a multilayer ceramic capacitor which can suppress the occurrence of cracks and delamination.

[0010]

Means and Action for Solving the Problems The above-mentioned object is to carry out a first step of heat-treating a multi-layer laminate of a dielectric composition layer and a conductor composition layer at a first temperature, and the first step. A second step of heating the laminated body that has undergone the step to a second temperature higher than the first temperature at a temperature rising rate of 450 ° C./hour or more, and the laminated body that has undergone the second step have the second step. A third step of performing heat treatment at a third temperature higher than the temperature,
It is solved by a method for producing a multilayer ceramic capacitor, wherein the conductor composition layer is composed of a thick film conductor composition containing fine particles of a conductive metal and an additive.

In the manufacturing method of the present invention, in the first step, the multilayer laminate of the dielectric composition layer and the conductor composition layer is heat-treated at a first temperature, that is, pre-baked to remove the binder, and In the second step, the laminate is
It is heated to a second temperature higher than the first temperature at a high temperature rising rate of 50 ° C./hour or more. The heating in the second step is called high-speed high-temperature firing. Then, in a third step, the laminate is heat-treated at a third temperature higher than the second temperature, that is, a peak temperature (dielectric aging temperature). That is, the main firing is performed. The production method of the present invention is characterized by performing heat treatment in such a firing temperature profile, and further characterized by containing an additive in addition to the conductive metal fine particles in the conductor composition layer. is there.

By performing the high-speed high-temperature firing before the main firing, the oxidation of the conductive metal in the conductor composition is suppressed in the main firing, and the oxidation expansion which is the main factor of the expansion of the conductor composition layer is suppressed. It Moreover, rapid high temperature firing increases the green strength of the dielectric composition layer during the main firing. This makes the dielectric composition layer resistant to expansion of the conductor composition layer due to oxidation of the conductor composition layer or due to combustion of carbon in the organic medium or desorption of oxygen from the oxidized conductive metal. Increase. Further, the organometallic compound added to the conductor composition layer suppresses the oxidative expansion of the conductor composition layer and controls the sintering shrinkage property to expand the dielectric composition layer during the main firing. And the compatibility with respect to shrinkage are improved, and SiO ₂ , Ti added in the conductor composition layer are added.
Inorganic compounds such as O ₂ and BaTiO ₃ have the same effect by treating the surface of the conductor composition layer. It is considered that these suppress generation of cracks and delamination in the laminate.

In the present invention, the laminated body is once cooled (including cooling) after the second temperature is reached by the heating in the second step, and then the laminated body is heated again to carry out the third step. It may be carried out, or after the second temperature is reached in the second step, the laminate may be heated as it is to carry out the third step.

The method of the present invention provides a high quality multilayer ceramic capacitor with reduced cracking. Moreover, according to the method of the present invention, the time for main firing can be shortened and productivity can be improved as compared with the conventional method. Further, if the third step is carried out as it is from the second step, the multilayer ceramic capacitor can be manufactured more efficiently. The present invention will be described in more detail below. A. Dielectric composition layer

In the present invention, as the dielectric composition layer, one generally used in a multilayer ceramic capacitor, that is, a layer made of a composition in which fine oxide powder is dispersed in a resin can be used. As the oxide powder, in addition to barium titanate (BaTiO ₃ ), neodymium titanate (Nd ₂ Ti ₂ O ₇ ), magnesium titanate (MgTiO ₃ ), calcium titanate (CaTiO ₃ ) oxide powder is also used. Be done. Other dielectric compositions include MnO, CeO ₂ , ZrO ₂ , and SiO.
Additives such as ₂ , Al ₂ O ₃ and NdO can be included. B. Conductor composition layer

In the present invention, the conductor composition layer is a thick film conductor composition in which fine particles of a conductive metal are dispersed in an organic medium and further contains an additive. A layer consisting of As additives in the thick film conductor composition, organometallic compounds described in JP-A-3-142808, such as Rh, Ni and C, can be used.
r, Pb, Cu, Fe, Mn, Zr, Ca, Co, B
In addition to organometallic compounds containing metals such as i and Zn, Si
Inorganic compounds such as O ₂ , TiO ₂ and BaTiO ₃ can also be used.

The organometallic compound used in the present invention is such that the metal part or metal oxide part thereof is insoluble in the conductive metal and / or the oxide of the metal part is non-reducing in the presence of the conductive metal. It is an organometallic compound. It is preferable that the organometallic compound be dissolved in a polymer binder and a volatile solvent and the conductive metal fine particles be dispersed in the solution. The amount of this organometallic compound is such that the metal portion constitutes at least 0.05% by weight of the thick film conductor composition. The amount of inorganic compounds such as SiO ₂ , TiO ₂ and BaTiO ₃ is 0.05% by weight or more of the thick film conductor composition.

The fine particles of the conductive metal in the conductor composition include Pd, Ag, Pt, Au, Cu, Ni, Ca and Z.
Fine particles of a conductive metal selected from r, oxide precursors and alloys of these metals, and mixtures thereof can be used. Next, in the present invention, it is a preferred composition as a thick film conductor composition,

“(A) Pd, Ag, Pt, Au, C
fine particles of a conductive metal selected from u, Ni, oxide precursors and alloys of these metals, and mixtures thereof,

(B) (i) An organometallic compound in which the metal site or metal oxide site is insoluble in the conductive metal and / or the metal site oxide is non-reducing in the presence of the conductive metal. And containing the organic metal compound (ii) dispersed in an organic medium dissolved in a solution of a polymer binder and a volatile solvent,

A suitable thickness for use in the electrodes of the multilayer capacitor, characterized in that the amount of the organometallic compound is such that the metal part constitutes at least 0.05% by weight of the total composition. The "membrane conductor composition" will be described in detail. (1) Conductive Metal The conductive metal that can be used in the present invention is Pd, Ag,
Pt, Au, Cu, Ni, alloys of these metals and their oxide precursors. As used herein, the term "precursor that is an oxide" refers to a zero-valent metal form (Me ^o under standard thick film firing conditions). ) Means a metal oxide reduced to.

The particle size distribution of the conductive metal is not critical to the effectiveness of the present invention, but in practice it is 0.1 to 10 μm, preferably 0.3 to 3 μm, based on the equivalent particle size.
Should be. It is preferred that the metal be readily dispersed in the organic medium and that the morphology be non-flake. (2) Organometallic compound The terms "organometallic compound" and "metal resinate" used herein are synonymous with an organometallic compound soluble in an organic medium.

One type of metal resinate is the reaction product of any of several organic compounds with a metal salt. The resulting compound is essentially a long-term organic molecule with one site occupied by one of the various metals. Another type of metal resinate is a chelate-type compound such as an organic titanate.

The composition of the organic part of the organometallic compound is not critical, but it must be thermally decomposed when the thick film conductor composition used in the present invention is fired in an oxidizing or non-oxidizing atmosphere. These organic moieties include carboxylates, naphthenates, tallates, alcoholates and the like.

Suitable organometallic compounds may range from highly fluid to very viscous liquids to solids. From the point of use in the present invention, the solubility of the resinate salt in the organic medium is of primary importance. Typically, the resinous metal is soluble in organic solvents, especially polar solvents such as toluene, methylene chloride, penzyl acetate and the like.
Also, they are soluble in non-polar solvents such as mineral spirits. Metal resinates and solutions of precious metal and base metals with resinates are commercially available. Suitable noble metal resinates are based on Ru, Rh, Re, Ir, Pt and mixtures thereof. Suitable resin acid precious metals are Mg, Si, Ti, V, Cr, Mn, Fe, Co, N
It is based on i, Cu, Zn, Zr, Nb, Ba, Ce, Ta, W and mixtures thereof.

Suitable organic titanates are described in British Patent No. 7
No. 72,675, particularly organic titanates of the formula (AO) _4x-3y TiO _y , where A is C _1-4 alkyl or a mixture of C _1-5 alkyl and C _1-6 acyl. , O is an oxygen atom that covalently bonds two titanium atoms, x is an integer of 1-12, and y is 0 or 1-.
A hydrolyzable metal alcoholate of titanium (corresponding to an integer of 3 × / 2). The alkyl group may be either straight or branched. Suitable organic titanates include titanium acetylacetonate and tetraoctylene glycol titanium chelates.
Other organic titanates of this type are Ken-React
Bul. No. KR-0278-7 Rev. (Ke
nrich Petrochemcals. lnc. Bayon, NJ) and "Versatile
Tyzor Organic Tita-nate
Du Pont Bul. No. E-38
961.

The resin acid metal is a thick film of the present invention at a concentration such that the metal or metal oxide content of the resin acid salt constitutes 0.05 to 5% by weight, preferably 0.1 to 1% by weight of the total composition. Used in conductor compositions.

In order to completely and uniformly disperse the compound in the organic medium, it is essential that the organometallic compound be soluble in the rest of the organic medium. In order to achieve such a uniform dispersion, the organometallic material binds to the surface of the conductive metal particles and then decomposes as firing continues to produce the corresponding metal or metal oxide, which is then sintered. Begin to. (3) Polymer binder solution

The second important ingredient in the organic medium is a solution of the polymeric binder in an organic solvent. The main purpose of this part of the organic medium is to serve as a vehicle for dispersing the finely divided solids of the composition in a form such that it can be readily applied to a ceramic or other substrate. Therefore, this part of the organic medium must first of all be such that the solid is dispersible and of sufficient stability. Secondly, the rheological properties of the organic medium must be such that it gives the dispersion good applicability.

Most thick film compositions are applied to the substrate by screen printing. Therefore, they must have a suitable viscosity so that they can easily pass through the screen. Furthermore, they should be thixotropic in order to solidify rapidly after screen printing and thereby give good resolution. While rheology is of primary importance, the organic medium should provide adequate wetting to solids and substrates, good drying rates, sufficient dry film strength to withstand rough handling, and good bakeability. It is preferable to mix them. Also, a satisfactory appearance of the fired composition is important.

In view of these criteria, a wide range of polymers and solvents can be used as the main dispersion medium.
Typically, the dispersion medium for most thick film compositions is a solution of the resin in a solvent that often also contains a thixotropic agent and a wetting agent. The solvent usually boils within the range of 130-350 ° C.

A very frequently used resin for this purpose is ethyl cellulose. However, resins such as ethyl hydroxyethyl cellulose, wood rosin, mixtures of ethyl cellulose and phenolic resins, polymethacrylates of lower alcohols and monobutyl ether of ethylene glycol monoacetate can also be used.

Suitable solvents include kerosene, mineral spirits, dibutyl phthalate, butyl carbitol, butyl carbitol acetate, hexylene glycol, high boiling alcohols and alcohol esters. Various combinations of these and other solvents are formulated to obtain the desired viscosity, volatility and compatibility with the dielectric tape. Also, a water-soluble solvent system can be used.

Among the commonly used thixotropic agents are hydrogenated castor oil, its dielectric and ethyl cellulose. Of course, it is not always necessary to include a thixotropic agent. This is because the solvent / resinity combined with the shear thinning properties inherent in either suspension may be suitable alone in this regard. Suitable wetting agents include phosphate esters and soy lecithin.

The ratio of organic medium to solids in the paste dispersion varies considerably and depends on the method in which the dispersion is applied and the type of organic medium used. Normally, the dispersion will contain 40-90% by weight solids and 60-10% by weight organic medium in order to obtain a good coating. The thick film conductor composition used in the present invention preferably contains 45 to 65% by weight of metal solids and 55 to 35% by weight of organic medium.

The paste is conveniently prepared using a three roll press. The viscosity of the paste is typically 0.1 to 300 Pa-s when measured at room temperature using a Brookfield viscometer at low, medium and high shear rates. The amount and type of organic medium (vehicle) used is
It is largely determined by the desired final formulation viscosity and print thickness. The organic vehicle must provide excellent dispersibility and burn out cleanly at low temperatures (400-450 ° C) during the firing cycle.

In view of these criteria, the vehicle system suitable for the present invention consists of ethyl hydroxyethyl cellulose dissolved in a mixture of β-terpineol, mineral spirits and other solvents. Also, ethyl cellulose and other solvents can be used. Normal,
A thixotropic agent is added to improve the line resolution by screen printing. (4) Preparation

The thick film conductor composition used in the present invention is prepared by dissolving an organometallic compound in a polymer / solvent solution, mixing a conductive metal powder into an organic medium, and then kneading the composition to prepare a powder. Can be easily prepared by uniformly and stably dispersing it in a liquid medium. C. Manufacture of multilayer laminates

In the present invention, the dielectric composition layer and the conductor composition layer as described above are stacked in an intervening arrangement as in the case of manufacturing a normal multilayer ceramic capacitor, and if desired, individual layers are stacked from the stacked product. Dicing the part.
Thus, a multi-layer laminate of the dielectric composition layer and the conductor composition layer is manufactured. D. Firing of multilayer laminate (1) First step (preliminary firing)

In the first step of the present invention, the multi-layer laminate of the dielectric composition layer and the conductor composition layer is heat-treated at the first temperature. This is to remove (de-binder) the organic resin in the conductor composition layer and the dielectric composition layer by slowly burning it out to avoid rapid gas generation and partial destruction in the subsequent heating step. To be done. The first temperature and the heating time are selected depending on the composition of the dielectric composition layer and the conductor composition layer, particularly the type of organic solvent used, but the first temperature is usually 300 ° C to 450 ° C.
The temperature range of ℃, the temperature rise time to this first temperature,
The entire time including the residence time at the first temperature and the temperature lowering time is selected from the time range of about 24 hours to 50 hours. (2) Second step (high-speed high-temperature firing)

In the second step of the present invention, the laminate obtained in the first step is subjected to the second step at a temperature rising rate of 450 ° C./hour or more.
Heat to the temperature of. The second temperature is higher than the first temperature and lower than the third temperature, that is, the peak temperature (dielectric aging temperature). The second temperature is selected depending on the composition of the dielectric composition layer and the conductor composition layer, and for example, when the conductive metal of the conductor composition layer is Pd, the second temperature is around the reduction temperature of Pd. It is desirable that the temperature is about 800 ° C or higher. In the heat treatment of the second step, the temperature rising rate is set to 450 ° C./hour or more.

After the second temperature is reached, the temperature may be maintained for a certain period of time or cooled immediately after the temperature is reached, or after the temperature is reached, the heat treatment in the third step may be started. .. The holding time in the case of holding the second temperature for a certain time is selected depending on the heat capacity of the laminated body to be fired, but is, for example, about 10 minutes. After being kept at a constant temperature in this way, it may be cooled, or subsequently, the heat treatment in the second step may be started. The rate of temperature decrease in the case of cooling immediately after reaching the second temperature or in the case of cooling after holding for a certain period of time is, for example, 50 ° C./hour or more. When the temperature is lowered from the second temperature, rapid cooling is preferable because gradual cooling may cause the metal in the conductor composition to oxidize during the temperature lowering to cause cracks. From this viewpoint, the heating furnace for carrying out the second step is preferably of the belt type. This is because the box type generally has a low temperature once it reaches a high temperature, and it is also difficult to control the temperature of the temperature decrease. (3) Third step (main firing)

In the third step of the present invention, the laminated body which has undergone the second step is heated at a third temperature, that is, a peak temperature (dielectric thermal temperature). The temperature rising ratio up to the peak temperature is not particularly limited, but is, for example, 50 to 450 ° C./hour.

The peak temperature is selected depending on the dielectric material, but is, for example, 1000 to 1400 ° C. The holding time at the peak temperature is about 1 to 4 hours. The cooling rate when cooling from the peak temperature is, for example, 50 to 400 ° C.
/ Time.

[0045]

The present invention will be described in more detail by the following examples. Example 1 and Example 2 The effect of the firing temperature profile of the present invention on the oxidation of conductive metals in thick film conductor compositions was investigated.

A thick film conductor composition was prepared containing 47 wt% Pd as the conductive metal, 0.5 wt% calcium resinate and 0.5 wt% zirconium resinate as the organometallic compound, and 52 wt% organic medium. ..

This thick film conductor composition was cast into a 20 mil thick film on an alumina substrate and dried until all paste solvent was removed. This resulted in a dried paste film approximately 100-300 microns thick. This was designated as Sample 1.

Example 1: Sample 1 was heated to 900 ° C. at a temperature rising rate of 600 ° C./hour, and its thermal analysis (TGA) showed that it was 400 ° C., 500 ° C., 600 ° C., 700 ° C., 8 ° C.
The degree of oxidation of Pd when the temperature reached 00 ° C. and the maximum temperature, respectively, was measured and expressed as a percentage.

Example 2 Sample 1 was heated from room temperature to 400 ° C. for 40 hours, then held at 400 ° C. for 2 hours and then cooled to room temperature in about 6 hours (this is called pre-baking 1). Then, at a temperature rise rate of approximately 1800 ° C / hour, 900
It was heated for 20 minutes until it reached to 0 ° C., kept at 900 ° C. for 10 minutes, and cooled to room temperature at a cooling rate of about 1800 ° C./hour (this is called high-speed high-temperature treatment 1). Then, as in Example 1, the temperature was raised to 900 ° C. at a heating rate of 600 ° C./hour
The degree of Pd oxidation during the process was measured. The results of Example 1 and Example 2 are shown in FIG. Example 3 and Example 4 The effect of the firing temperature profile of the present invention on the expansion of the thick film conductor composition layer was investigated.

Example 3: Sample 1 heat-treated by pre-baking 1 at 400 ° C. for 48 hours was heated to 1 at a heating rate of about 200 ° C./hour.
It was heated to 300 ° C., and the expansion of the conductor composition layer during that time was measured using an dilatometer. The substrate was mounted on a dilatometer and the shrinkage as a function of temperature was measured. The shrinkage of the film, measured in microns, was measured throughout the bake cycle and used to calculate the shrinkage for the green dry film thickness.

Example 4: Sample 1 heat-treated at 400 ° C. for 48 hours by pre-baking 1 was heated at 900 ° C. by high-speed high-temperature treatment 1.
Heated up. After that, it was heated to 1300 ° C. in the same manner as in Example 3, and the expansion of the conductor composition layer during that period was measured. The results of Examples 3 and 4 are shown in FIG.

Also, Pd 48 wt% and organic medium 5
A thick film conductor composition consisting of 2 wt% was prepared and tested in the same manner as in Examples 3 and 4, and even with the thick film conductor composition containing no additive, pre-baking 1 and high-speed high-temperature treatment 1 As a result, the effect of suppressing the oxidative expansion and controlling the sintering shrinkage property was observed to some extent. Examples 5 to 7 The effect of the additive in the thick film conductor composition of the present invention on the oxidation of the conductive metal in the thick film conductor composition was investigated.

Example 5: Pd50 w as a thick film conductor composition
A sample prepared in the same manner as in sample 1 except that a thick film conductor composition composed of t% and an organic medium of 50 wt% was heated to 900 ° C. at a temperature rising rate of about 200 ° C./hour, and 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800
The degree of oxidation of Pd was measured when the temperature reached ℃ and the maximum temperature, respectively. The degree of Pd oxidation was expressed as a percentage in the same manner as in Example 1.

Example 6: The composition of the thick film conductor composition was Pd50.
A sample was prepared and heat-treated in the same manner as in Example 5 except that wt%, manganese resinate as an additive, 2 wt%, and an organic medium, 48 wt% were used to measure the degree of Pd oxidation.

Example 7: The composition of the thick film conductor composition was Pd50.
A sample was prepared and heat-treated in the same manner as in Example 5 except that wt%, calcium resinate as an additive, 2 wt%, and an organic medium, 48 wt% were used to measure the degree of Pd oxidation.
The results of Examples 5 to 7 are shown in FIG. Example 8 The effect of the addition amount of the additive (calcium resinate) in the thick film conductor composition of the present invention on the oxidation of the conductive metal in the thick film conductor composition was investigated. A sample was prepared in the same manner as in Example 7 except that the amount of calcium resinate in the thick film conductor composition was 1 wt%, and the sample was heated to 900 ° C. to measure the degree of Pd oxidation. The result shows that the amount of calcium resinate is 0
The results are shown in FIG. 4 together with the results of Example 5 where wt% is present and Example 7 where 1 wt% is present. Examples 9 to 12 The effect of the firing temperature profile of the present invention on the green strength of the thick film conductor composition was investigated.

Niobium titanate is used as the dielectric group oxide.
A 40 μm thick green sheet containing calcium titanate and magnesium titanate and an organic medium was prepared. The thick film conductor composition used in Examples 1 and 2 was printed on this green sheet and dried until all paste solvent was removed. By this, about 4.0
A μm thick dried paste film was obtained. Sample 2 was prepared by stacking 20 green sheets on which the conductor composition layer was formed.

Example 9: Sample 2 was heated to 1000 ° C. at a temperature rising rate of about 200 ° C./hour, and 400 ° C. and 500 on the way.
The green strength was measured when the temperature reached 600 ° C, 600 ° C, 700 ° C, 800 ° C, and 1000 ° C, respectively.

Example 10: Sample 2 was prebaked 1 to 400
The sample was heat-treated at 48 ° C. for 48 hours and then heated to 1000 ° C. at a temperature rising rate of about 200 ° C./hour in the same manner as in Example 9, and the green strength in the middle was measured.

Example 11: Sample 2 was prebaked 1 to 400
Heat treatment at 48 ° C for 48 hours, and then heat for 20 minutes at a temperature rising rate of about 1800 ° C / hour until 800 ° C is reached.
The temperature was held at 00 ° C for 10 minutes and cooled to room temperature at a temperature decrease rate of about 1800 ° C / hour (this is called high-speed high-temperature treatment 2). Then, in the same manner as in Example 9, the temperature was raised to 1000 ° C. at a temperature rising rate of about 200 ° C./hour, and the green strength in the middle was measured.

Example 12: Sample 2 was prebaked 1 to 400
The sample was heat treated at 48 ° C. for 48 hours, then heated to 900 ° C. by the high-speed high temperature treatment 1, and then heated to 1000 ° C. at a temperature rising rate of about 200 ° C./hour, and the green strength in the middle was measured.

The green strength is about 2 mm apart from each other.
Sample 2 is placed so as to straddle between two stainless steel plates, and 12.5 mm /
A constant force of min was applied and the magnitude of the force when the sample broke was represented by gf. The results of Examples 9 to 12 are shown in FIG. Examples 13 to 16 The effect of the firing temperature profile of the present invention on the crack generation due to the main firing was examined.

Example 13: Sample 2 was heated to 1330 ° C. at a heating rate of about 200 ° C./hour, and 400 ° C., 50
Occurrence rates of side cracks and plane cracks were measured when reaching 0 ° C, 600 ° C, 700 ° C, 800 ° C, 1000 ° C, and 1200 ° C, respectively. The rate of occurrence of cracks was also measured after the temperature reached 1330 ° C and held for 2 hours.

Example 14: Sample 2 was prebaked 1 to 400
The sample was heat treated at 48 ° C. for 48 hours and then heated to 1330 ° C. at a temperature rising rate of about 200 ° C./hour in the same manner as in Example 13, and the incidence of side and plane cracks in the middle was measured.

Example 15: Sample 2 was prebaked 1 to 400
Heat treatment at 48 ° C. for 48 hours, then heat treatment to 800 ° C. by high-speed high-temperature treatment 2, and then heat to 1330 ° C. at a temperature rising rate of about 200 ° C./hour in the same manner as in Example 13 to remove side and plane cracks on the way. The incidence was measured.

Example 16: Sample 2 was prebaked 1 to 400
Heat treatment at 48 ° C. for 48 hours, then heat treatment to 900 ° C. by high-speed high-temperature treatment 1, and then heat to 1330 ° C. at a heating rate of about 200 ° C./hour in the same manner as in Example 13 to remove side and plane cracks on the way. The incidence was measured.

Here, the side crack means the sample 2
The cracks generated on the surface of the thickness of the green sheet and the conductor composition layer, and the plane cracks are cracks generated on the surface of the uppermost layer of the laminate. The occurrence rate is the percentage of the number of samples with cracks in the number of tested samples (10). The results of Examples 13 to 16 are shown in Table 1 and Table 2.

[0067]

[Table 1]

[0068]

[Table 2]

Example 16 which did not undergo the first step (preliminary firing)
No cracks were generated, but so-called delamination, in which the conductor composition layer and the dielectric composition layer were separated, occurred. No delamination occurred in Examples 15 and 16 which were heat-treated with the firing profile of the present invention. Examples 17 to 34

In the second step (high-speed high-temperature firing) of the firing method of the present invention, the rate of temperature rise, the second temperature, the holding time at the second temperature, and the rate of temperature drop from the second temperature cause cracks. I investigated the effect on them.

Sample 2 was heat-treated under 18 kinds of conditions in which the temperature rising ratio, the second temperature, the holding time at the second temperature, and the temperature falling ratio from the second temperature were different, and then the third step. (Main firing) was carried out, and the number of side cracks and plane cracks (occurrence rate) and the size of the cracks were measured.

The results of Examples 17 to 34 are shown in Table 3. Table 3
In the above, the temperature decrease ratio of "-" indicates that the temperature was removed from the furnace immediately after reaching or holding the second temperature. In addition, Example 21 is a confirmation test of Example 20 and Example 28 is a confirmation test of Example 27.

[0073]

[Table 3] Example 35 to Example 43 In the method of the present invention, the influence of the magnitude of the temperature rise ratio in the second step (high-speed high-temperature firing) on crack generation was examined.

Sample 2 was heated to 900 ° C. under 9 kinds of conditions with different temperature rising ratios, and subsequently heated to 1300 ° C. at 200 ° C./hour and kept at 1300 ° C. for 2 hours. The number of samples tested under the same conditions is 5 each.
The number (occurrence rate) of those side cracks and plane cracks and the size of the cracks were measured. Example 35
~ The results of Example 43 are shown in Table 4.

[0075]

[Table 4]

From the results of Examples 1 to 16, by performing the high-speed high-temperature firing before the main firing, the oxidation of Pd in the conductor composition was suppressed during the main firing, and the expansion of the conductor composition layer was remarkable. In addition, the high-speed high-temperature firing suppresses the expansion of Pd slightly during the main firing from 400 ° C to 800 ° C.
To increase the green strength of the dielectric composition layer in
Furthermore, it can be seen that the calcium resinate and the zirconium resinate in the conductor composition layer suppress the oxidative expansion of the conductor composition layer and control the sintering shrinkage characteristics.
It is also apparent that the present invention suppresses the generation of cracks. Furthermore, Examples 17 to 34 and Example 35
From the results of Example 43, it can be said that the preferable condition for the firing profile of the present invention is to perform firing at a temperature rising rate of 450 ° C./hour or more after the first step. Example 44 A multilayer ceramic capacitor was manufactured according to the method of the present invention, and the crack generation state in the finished product was examined.

Using the same dielectric composition and thick film conductor composition as used in Examples 9 to 12, a multilayer ceramic capacitor (unfired) was manufactured, and after heat treatment by prebaking 1, 100 mm / min belt furnace for heating rate 3
High-speed high-temperature baking was performed at 600 ° C./hour to 900 ° C., and then main baking was performed at 900 ° C. for 10 minutes. Thereafter, a terminal electrode was formed, and Ni and Sn / Pb or Sn were plated to obtain a finished multilayer ceramic capacitor. 1
None of the 000 finished products were cracked or delaminated. Obtained.

[0078]

As described above, according to the method of the present invention, it is possible to obtain a high quality multilayer ceramic capacitor in which the occurrence of cracks and delamination is reduced. Moreover, according to the method of the present invention, the time for main firing can be shortened and productivity can be improved as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the effect of the firing temperature profile of the present invention on the oxidation of a conductive metal in a thick film conductor composition.

FIG. 2 is a diagram for explaining the influence of the firing temperature profile of the present invention on the expansion of the thick film conductor composition layer.

FIG. 3 is a diagram for explaining the effect of the additive in the thick film conductor composition of the present invention on the oxidation of the conductive metal in the thick film conductor composition.

FIG. 4 is a diagram for explaining the effect of the additive in the thick film conductor composition of the present invention on the oxidation of the conductive metal in the thick film conductor composition.

FIG. 5 is a diagram for explaining the influence of the firing temperature profile of the present invention on the green strength of the thick film conductor composition.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoichi Sakuta 4997 Shinyoshida-cho, Kohoku-ku, Yokohama-shi, Kanagawa DuPont Japan Central Research Institute (72) Inventor Takayuki Ooba 4997 DuPont, Shin-yoshida-cho, Kohoku-ku, Yokohama, Kanagawa Prefecture Japan Central Research Institute

Claims (1)

[Claims] 1. A first step of heat-treating a multi-layer laminate of a dielectric composition layer and a conductor composition layer at a first temperature, and a laminate subjected to the first step at 450 ° C./hour or more. A second temperature which is higher than the first temperature at a heating rate of
And a third step of heat-treating the laminated body that has undergone the second step at a third temperature higher than the second temperature, wherein the conductor composition layer is made of a conductive metal. A method for producing a multilayer ceramic capacitor, comprising a thick film conductor composition containing fine particles and an additive.