JPH0323503B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a dielectric composition, particularly a dielectric composition having a low firing temperature. [Problem to be Solved by the Invention] Multilayer ceramic capacitors (MLCs) are the most widely used form of ceramic capacitors because of their high volumetric efficiency and therefore their small dimensions. These capacitors are manufactured by stacking and firing together thin sheets of ceramic dielectric printed with appropriate electrode patterns. Each patterned layer is offset from adjacent layers to expose alternating electrode layers at each end of the assembly. The exposed ends of the electrode pattern are coated with a conductive material that electrically connects all the layers of the structure, thereby forming a group of parallel connected capacitors in the stacked structure. This type of capacitor is often referred to as a monolithic capacitor. The thin sheets of ceramic dielectric used in the manufacture of MLCs are composed of layers of finely divided dielectric particles held together by an organic polymeric material. Green ceramics are made by slip casting a slurry of derivative particles dispersed in a solution of polymer, plasticizer, and solvent onto a carrier such as polypropylene, mylar polyester film, or stainless steel. The thickness of the cast film can be adjusted by passing it under a doctor blade to form a thin "green tape". Metallizing agents useful in the production of conductors for multilayer capacitors typically include finely divided metal particles that are applied to the green tape in the form of a dispersion of the particles in an inert liquid vehicle. . Although the "green tape" method described above is more widely used, there are nevertheless other ways in which MLCs can be manufactured using the dielectric compositions of the present invention.
One of them is the so-called "wet method". In one embodiment, this involves passing a flat substrate through a falling sheet of dielectric one or more times to form a dielectric layer (see U.S. Pat. No. 3,717,487).
may be included. Other methods for manufacturing MCLs include forming a paste of dielectric material and then screen printing alternating layers of dielectric and metal with intervening drying steps until the designed structure is created. is included. A second electrode layer is then printed on top of the dielectric layer and the entire assembly is fired together. Monolithic multilayer capacitors are typically manufactured by co-firing a barium titanate-based formulation and a conductive electrode material at temperatures between 1200 and 1400 DEG C. in an oxidizing atmosphere. This method produces durable, well-sintered capacitors with high dielectric constants, such as 1000 or more. However, firing under these conditions results in a high melting point, good oxidation resistance at high temperatures, sinterability at the maturing temperature of the dielectric, and a tendency to interact with the dielectric at the sintering temperature. requires the least electrode material. These requirements generally limit the choice of electrode materials to the noble metals platinum and palladium or platinum alloys, palladium alloys and gold alloys. See also U.S. Pat. No. 3,872,360 for the manufacture of monolithic multilayer capacitors. Some attempts have been made to lower the ripening temperature of derivatives by using "sintering aids." Addition of bismuth oxide or bennite to barium titanate lowers the ripening temperature to about 1200°C (US Pat. No. 2,908,579). Aging temperatures of 1200 DEG to 1290 DEG C. may be achieved by adding phosphate to the titanate as described in US Pat. No. 2,626,220. However, in each of these cases, the reduction in aging temperature is not sufficient to allow the use of co-fired silver electrodes, and the dielectric properties are often degraded. Another technique for lowering the sintering temperature of titanate-based dielectrics is to mix high-temperature ferroelectric phases (titanate, zirconate, etc.) with glasses that age at relatively low temperatures. This is due to Examples of this method include U.S. Pat.
No. 3638084, No. 3682766 and No. 3811937. A disadvantage of this technique is that the dilution effect of the glass often makes the dielectricity of the mixture relatively small. By using a lead-based dielectric instead of barium titanate, Bouchard
The problem of dielectric compositions with low firing salinities and dielectric constants as high as 6000 for use in - type capacitors has been very successfully addressed. These substituted lead titanate compositions correspond to the formulas below. (Sr _x Pb _1-x TiO ₃ ) _a (PbMg _r W _s O ₃ ) _b where x=0~0.10 r=0.45~0.55 a=0.35~0.5 s=0.55~0.45 b=0.5~0.65 Σ( r+s)=1, and Σ(a+b)=1 Such materials are described in Bouchard's U.S. Pat.
No. 4048546, No. 4063341 and No. 4228482. Most recently, U.S. Patent Claim No. 713,099 (September 1985)
12, 2003) describes an improvement on the derivative composition of Bouchard and describes a more suitable composition of the Z5U-type. Here, Bouchard's composition is doped with trace amounts of transition metal oxides and zirconates and stannates of cadmium and zinc. Despite the virtual progress towards obtaining larger dielectric constants, the electronic industry is still looking for even higher dielectric constants (K) in the order of 8000 and even higher, with lower PbO contents (i.e. <10 wt%). , and yet a ratio of 30/70 palladium/
It anticipates the need for dielectric compositions that can be used with conventional silver-containing electrodes, such as silver electrodes. SUMMARY OF THE INVENTION The present invention therefore relates in a first aspect to a composition consisting of a mixture of finely divided particles as described below for forming a densified dielectric at low firing temperatures. a Curie point modifier selected from (a) _BaTiO3 , (b) A(Zn1 _{/3Nb2 /3} ) _O3 , (c) _BaZrO3 , _PbZrO3 , _BaSnO3 , _PbSnO3 and mixtures thereof; (d) Manganese-doped borate metal flex (F)
and/or its oxide precursor, provided that the ratio of (a) to (d) is stoichiometrically substantially equal to the following formula: (1-x) [(Ba _1-x Pb _x ) (Ti _1-(u+v) Zr _u Sn _v ) O ₃ ]+
X [A (Zn _1/3 Nb _2/3 ) O ₃ ] + Y [F] where A is selected from Pb, Ba and mixtures thereof, X = 2.5 to 11.5% by weight Y = 1.0 to 5.0% by weight u=0-0.125 v=0-0.125 x=0-0.125, and u+v=0.015-0.125. In these compositions, the zinc niobate metal acts both as a flux additive for the barium titanate and as a Curie point inhibitor. This latter behavior is completely unexpected. This is because lead zinc niobate has a higher Curie temperature of 140°C than that of barium titanate, for example. In a second aspect, the present invention comprises (1) applying a layer of electrically conductive electrode material dispersed in an organic medium to each of a number of layers of green tape made from the composition described above; (2) A large number of this green tape with layers of electrodes are laminated to form an assembly of alternating layers of green tape and electrode material, and (3) the assembly of step (2) is
A method of forming a monosilic capacitor comprising the steps of firing at 1000 DEG to 1150 DEG C. to remove the organic medium and organic binder from the assembly and sintering the conductive electrode material and dielectric material. In a third aspect, the invention provides at least
A dielectric ceramic body having a conductivity of 8000 and at least two spaced apart metal electrodes in contact with the ceramic body consisting essentially of a composition as described above, the densification of the dielectric solid and the metal This invention relates to a ceramic capacitor fired at 1000 to 1150°C to sinter the electrodes. In a fourth aspect, the present invention relates to a tape casting composition comprising a dielectric composition as described above dispersed in a solution of a binder polymer in a volatile non-aqueous solvent. In a fifth aspect, the invention comprises casting a thin layer of the dispersion described above onto a flexible substrate such as a steel belt or polymer film and heating the cast layer to remove the volatile solvent therefrom. Concerning how to form a green tape by. In a sixth aspect, the present invention relates to a screen printable thick film composition comprising a dielectric composition as described above dispersed in an organic medium. [Prior Art] U.S. Pat. No. 4,266,265 relates to a method for making a ceramic capacitor, in which the precursor dielectric powder is a mixture of alkaline earth metal titanate and cadmium silicate. The alkaline earth metal titanates contain barium-lead-titanate and barium-lead-titanate-zirconate which can be doped with donor atoms such as Bi, Nb, Ta, Sb, W, La and U. be. These materials are fired at 1100°C. U.S. Pat. No. 4,283,753 has a dielectric constant of at least 5000 and includes (a) large divalent ions selected from Ba, Pb, Sr and Ca, (b) small 4 ions selected from Ti, Zr, Sn and Mn. Valence ions, (b) Bi, Nb,
(d) acceptor ions for charge compensation selected from Cd, Zn, Cu, Li and Na; (d) acceptor ions for charge compensation selected from Cd, Zn, Cu, Li and Na; e)
The present invention relates to a ceramic capacitor composed of BaTiO ₃ doped with glass-forming ions selected from B, Si, Ge, P and V. These materials are said to have dielectric constants exceeding 5000, and are densified by firing at about 1100°C. U.S. Pat. No. 4,335,216 relates to dielectric ceramic compositions fired at 1000-1150°C, where the precursor dielectric powders are BaTiO ₃ , SrTiO ₃ ,
_BaZrO3 , _TiO2 and _Mn2O to ZnO, _SiO2 ,
It is a mixture mixed with glass frit containing B ₂ O ₃ , PbO, Bi ₂ O ₃ and CdO. This composition is used to make multilayer ceramic capacitors. U.S. Pat. No. 4,379,854 relates to a dielectric composition containing finely divided particles of BaTiO ₃ , SrZrO ₃ and flux powders ZnO and B ₂ O ₃ which function as Curie point modifiers. This material is fired at 1000-1150°C. U.S. Patent Application Publication No. 2125028A is 1050-1200
Formula (a) that can be sintered at °C (Ba _1-x Me _x ) (Ti _1-y Me _x ′)
O ₃ (wherein Me is Ca and/or Sr,
Me′ is Zr and/or Sn), 100 parts by weight of the main component, PbTiO ₃ 65-90%,
A dielectric ceramic composition comprising 5 to 15 parts by weight, based on (a), of a second component (b) which is a mixture of 1 to 10% Pb ₅ Ge ₃ O ₁₁ and 1 to 30% BiTi ₂ O ₇ . This material is fired at 1050-1360°C. [Means for solving the problem] A. Dielectric material The BaTiO ₃ component of the composition of the present invention is commercially available in a suitable particle size. For purposes of the present invention, as well as other dielectric materials,
It is essential that the BaTiO ₃ also has an average particle size not larger than 2.0 μm and preferably smaller than 1.5 μm. An average particle size of 0.4 to 1.1 μm is more preferred. On the other hand, if the average particle size of the solid is less than about 0.1 μm, the particles become difficult to handle and are therefore less suitable. Other oxide components, namely zinc metal niobate, Curie point modifiers and fluxes, are easily prepared by mixing finely divided particles of the appropriate oxide or its precursor and calcining them in air. can. When it comes to zinc niobate metal and the Curie point modifier, the compound is
It is formed by firing at 800-1000°C for about 5 hours. This is a time and temperature sufficient to obtain complete reaction of the component oxides while avoiding excessive sintering and excessive grain size. "precursor"
The term refers to compounds that are converted to metal oxides by calcination in air. This includes hydrates, carbonates, hydroxides, nitrates, oxalates and alkosides. A suitable flux has a ZnO:B ₂ O ₃ ratio of 2.
Zinc borate, mixtures thereof, and precursors thereof. As per the known glass manufacturing method,
It will be appreciated that up to mol % of B ₂ O ₃ can be replaced by SiO ₂ , GeO ₂ , Al ₂ O ₃ or mixtures thereof. The flux used in the examples was prepared by baking a mixture of ZnO, boric acid and MnCO ₃ at 700°C for 18 hours.
It was later adjusted by milling. B. Green Tape Casting Solution As mentioned above, the green tape of the dielectric composition of the present invention is a dispersion of dielectric material in a solution of a polymeric binder and a volatile organic solvent. It is manufactured by casting onto a flexible substrate such as a film and then heating the cast layer to remove the volatile solvent therefrom. The organic medium in which the ceramic solids are dispersed contains a polymeric binder dissolved in a volatile organic solvent and optionally other dissolved substances, such as plasticizers, mold release agents, dispersants, stripping agents, antifouling agents, and wetting agents. It consists of a drug. For better binding efficiency, at least 5% by weight (95% by weight for ceramic solids)
It is preferred to use a polymeric binder of. However, 20% by weight (ceramic solids are 80%
It is further preferred to use a polymeric binder of no more than % by weight). It is desirable to use the lowest possible amount of binder to solids within these limits in order to reduce the amount of organic matter that must be removed by pyrolysis. In the past, a wide variety of polymeric materials have been used as green tape binders. For example, poly(vinyl butyral), poly(vinyl acetate),
Poly(vinyl alcohol), methyl cellulose,
Cellulose polymers such as ethylcellulose, hydroxyethylcellulose, methylhydroxyethylcellulose, atactic polypropylene, silicone polymers such as polyethylene, poly(methylsiloxane), poly(methylphenylsiloxane), polystyrene, butadiene/styrene copolymers, polystyrene, poly( various acrylic polymers and lower alkyls, such as vinylpyrrolidone), polyamides, high molecular weight polyethers, copolymers of ethylene oxide and propylene oxide, polyacrylamides, sodium polyacrylates, poly(lower alkyl acrylates), poly(lower alkyl methacrylates) and various copolymers and multipolymers of acrylates and methacrylates. Copolymer of ethyl methacrylate and methyl acrylate and ethyl acrylate,
Terpolymers of methyl methacrylate and methacrylic acid have been used previously as binders for slipcasting materials. Recently, in U.S. Patent Application No. 737,549, a compatible multipolymer consisting of 0-100% by weight of a C _1-8 alkyl methacrylate, 100-1% by weight of a C _1-8 alkyl acrylate and an ethylenically unsaturated Carboxylic acid or amine 0~
Discloses a 5% by weight mixture of organic binders. Their use is preferred for the dielectric compositions of the present invention because the polymers allow the use of a minimum amount of binder and a maximum amount of dielectric solids. For this reason, the above U.S. patent application no.
The disclosure of No. 737549 is incorporated herein by reference. The solvent component of the casting solution is of sufficient volatility that the polymer is completely dissolved and that the solvent can be evaporated from the dispersion by application of relatively low levels of heat at atmospheric pressure. Select as follows. In addition, the solvent must boil well below the boiling point and decomposition temperature of any other additives contained in the organic medium. Therefore, solvents with atmospheric boiling points below 150°C are most often used. Such solvents include benzene, acetone, xylene, methanol, ethanol, methyl ethyl ketone,
These include 1,1-trichloroethane, tetrachloroethylene, amyl acetate, 2,2,4-triethylpentanediol-1,3-monoisobutyrate, toluene, and methylene chloride. The organic medium often also contains small amounts of plasticizers proportional to the binder polymer, which serve to lower the glass transition temperature (Tg) of the binder polymer. However, the use of such materials should be minimized to reduce the amount of organic material that must be removed when the cast film is fired. The choice of plasticizer is, of course, primarily determined by the polymer that has to be modified. Among the plasticizers that have been used in various binder material systems are diethyl phthalate, dibutyl phthalate, octyl phthalate, butyl benzyl phthalate, alkyl phosphates, polyalkylene glycols, glycerol, poly(ethylene oxide), hydroxy Ethylated alkylphenols, dialkyldithiophosphonates and poly(isobutylene). Of these, butylbenzyl phthalate is most frequently used in acrylic polymer material systems. This is because it can be used effectively at relatively small concentrations. C. Thick Film Paste It is often desired to apply the compositions of the present invention as a thick film paste by techniques such as screen printing. When applying the dispersion as a thick film paste, conventional thick film organic media can be used by appropriate rheology adjustment and the use of less volatile solvents. In this case, the composition must have a suitable viscosity so that it can easily pass through the screen. Additionally, the composition should be (thixotropic) in order for it to solidify rapidly after passing through the screen, thereby providing good resolution. Although rheological properties are most important, the organic medium preferably also has adequate wetting of the solid and substrate, good drying rate, sufficient dry film strength to withstand rough handling, and good sinterability. It is formulated to bring about. It is also important that the appearance of the fired composition is satisfactory. Considering all these points, various inert liquids can be used as organic media. The organic vehicle for most thick film compositions is typically a solution of a resin in a solvent, and often a solvent solution containing both a resin and a thixotropic agent. This solvent typically boils within the range of 130-350°C. Particularly suitable resins for the above purpose are polymethacrylates of lower alcohols and monobutyl ethers of ethylene glycol monoacetate. The most widely used solvents for thick film applications are terpenes such as alpha- or beta-terpinenol,
Mixtures of these with other solvents such as kerosene, dibutyl phthalate, butyl carbitol, butyl carbitol acetate, hexylene glycol and high boiling alcohols and alcohol esters. Various combinations of these and other solvents are formulated to obtain the desired viscosity and volatility requirements for each application. Among the commonly used thixotropic agents are hydrogenated castor oil and its derivatives. The concomitant use of a thixotropic agent is not necessarily necessary, as the solvent/resin properties alone with their inherent viscosity reduction are probably adequate in this respect for either suspension. The proportion of organic medium to inorganic solids in the dispersion is highly variable and depends on the method of applying the dispersion and the type of organic solvent used. Usually, in order to obtain good coverage, the dispersion contains complementary amounts of 60-90% by weight of solids and 40-10% by weight of organic medium; such dispersions usually have a semi-liquid viscosity. Generally called "paste". This paste is conveniently prepared in a three-roll mill. The viscosity of the paste is typically within the following ranges as measured on a Brookfield viscometer at low, medium, and high shear rates at room temperature.

TABLE The amount and type of organic vehicle used is determined primarily by the final desired formulation viscosity and print thickness. D. Fabrication of Capacitors As described above, a number of multilayer capacitors are fabricated by printing electrode metallization in a desired pattern onto a green tape dielectric substrate. This printed dielectric substrate is stacked and
Laminate and cut to form the desired capacitor structure. The green dielectric material is then fired to remove the organic medium from the electrode material and the organic binder from the dielectric material. Removal of these materials is accomplished by a combination of evaporation and pyrolysis during the calcination operation. In some cases it may also be desirable to include a pre-drying step prior to firing.
The thickness of unfired raw tape is typically about 1.2
~1.3 mil, with a thickness of approximately 0.9-1.0 mil upon firing. When firing the above capacitor assembly,
Preferably, a first calcination step is used in which the assembly is gradually heated to 100-550°C. This is effective in removing all of the organic material without damaging the stacked assembly. Typically, the complete combustion time for organics is 18 to 24 hours to ensure complete removal of organics. Once this is completed, the assembly is then heated more rapidly to the desired sintering temperature. The desired sintering temperature is determined by the physical and chemical properties of the dielectric material. Typically, the sintering temperature is selected to provide maximum densification of the dielectric material. For the dielectric compositions of the present invention, this temperature ranges from 1000 to 1150°C. However, those involved in capacitor manufacturing technology recognize that maximum densification is not necessarily required. Therefore, the term "sintering temperature" refers to the temperature (including the amount of time in residence) to obtain the desired densification of the dielectric material for each capacitor application. Although the sintering time also varies depending on the dielectric composition, it is usually preferably about 2 hours at the relevant sintering temperature. Once sintering is complete, the rate of cooling to ambient temperature is carefully controlled according to the resistance of the components to thermal shock. The following properties related to the ability of a given capacitor to function properly are mentioned in the examples. E Test Procedure Capacitance Capacitance is a measure of a material's ability to store charge and is expressed mathematically as C=KAN/t, where K is the dielectric constant, A is the area overlap of the electrodes, and N is the dielectric layer. , t indicates the thickness of the dielectric layer). The unit of capacitance is the farad or its fraction microfarad (10 ^-6 farad), nanofarad (10 ^-9 farad) or picofuard (10 ^-12 farad). Dissipation Factor Dissipation factor (DF) is a measure of the difference in phase angle between voltage and current. A perfect capacitor would have a phase angle of 90°. However, in practical dielectric systems, this phase angle difference is smaller than 90° by a certain amount σ due to leakage and relaxation losses.
Specifically, DF is the tangent of angle σ. Insulation Resistance Insulation resistance (IR) is the DC resistance of a charged capacitor.
It is a measure of the ability to withstand leakage in electrical current. Insulation resistance, expressed as ohms farads (ΩF), is a constant for any given dielectric regardless of capacitance. The following Examples and Comparative Examples are presented to specifically explain the effects of the present invention. Throughout this specification, all parts, percentages, and proportions are by weight unless stated otherwise. Example 1 Material Preparation A Barium Titanate Barium titanate is a commercially available material.
FujiHPBT-1 was mainly used, but good results were obtained using an alternative material made by Ferro (219-6).
was obtained by using A typical particle size distribution as measured by a Leeds and Northrup particle size analyzer (Microtrac) is shown below.

[Table] B Zinc Lead Niobate Zinc lead niobate is dissolved in isopropanol or other liquids using ZrO ₂ medium for 5 hours.
Produced by initial ball milling of 65.9% PbO, 26.1% Nb ₂ O ₅ and 8.0% ZnO (parts by weight). When dry, heat the mixed powder at 800℃ for 5 minutes.
Calcined for 1 hour followed by ball milling for 16 hours to give a typical particle size (D ₅₀ ) of 0.9 microtomels. C PbZrO ₃ or PbSnO ₃ These additives contain stoichiometric amounts of PbO under conditions similar to those used for zinc lead niobate.
It was prepared by grinding and sintering with ZrO ₂ or SnO ₂ . Particle size ( _D50 ) was typically between 0.7 and 1.0 micrometers. D BaZrO ₃ or BaSnO ₃ These were commercially available powders. _BaSnO3
(Transelco) is used as it was when purchased,
BaZrO ₃ was pre-milled. Typical particle size is 0.9~
It was 1.1 micrometers. E Frit/Flux Details of the production of the flux used in the present invention are shown in the following examples. BaTiO ₃ (Fuji HPBT-1) 80.0, PbSnO ₃ ,
12.50, Pb(Zn _1/3 Nb _2/3 ) O ₃ 3.82, BaSnO ₃ 2.50 and manganese doped zinc borate frit
Ceramic tape was prepared by casting a stirred slurry of 66.0 g of binder solution (DuPont 5200) on a powder mixture of 1.50 g. This zinc borate frit is ZnO74.83
%, B ₂ O ₃ 21.35% and MnCO ₃ 3.82%, and was prepared by calcining ZnO, boric acid and MnCO ₃ at 700° C. for 18 hours and then milling to a particle size smaller than 2 micrometers. Cut this ceramic tape to approximately 0.4 x 0.4 x
Laminated into 0.025″ plates. Following a bakeout step in air at 750°C to remove organic binders, these plates were 2 to 1/2 times laminated at 1100°C in a closed alumina crucible. Baked for an hour. After baking,
Electrodes were attached to the plate using silver paste (Du Pont 6730) and the dielectric properties were measured at 1 KHz and 1.0 volt. The Curie temperature is 35℃ and the dielectric constant is 8400
DF=1.2% at ±500. Examples 2, 3 and 4 Ceramic tapes were made using the following ceramic compositions (parts by weight) with different amounts of zinc borate frits added. That is, BaTiO ₃ (HPBT-1)
82.0, Pb(Zn _1/3 Nb _2/3 )O ₃ 6.0, PbZrO ₃ 5.5, and BaZrO ₃ 5.0. Zinc borate frit contains 5.4% by weight of ZnO, 23.0% by weight of boric acid, 11.7% by weight _{of MnCO3} and
Made from a mixture of 20.0% by weight BaCO ₃ . this
It was baked at 700°C for 5 hours and then ground to a particle size of 1.25 micrometers. In these examples, BaCO ₃ was added along with MnCO ₃ to keep the cations stoichiometrically proportional to BaTiO ₃ . Fritz levels 1.25, 1.50 and 1.75 wt%
Multilayer ceramic capacitors with 1.0 mil dielectric layer and 30Pd-70Ag electrodes were fabricated. These capacitors were fired as in the previous example with the following results.

[Table]
Example 5 BaTiO ₃ (HPB
-T) 87.0, Pb(Zn _1/3 Nb _2/3 ) O ₃ 11.5 and zinc borate frit 1.5, but a plate capacitor was produced in the same manner as in Example 1. When firing in the same manner as in the previous examples, the Curie temperature is
At 35℃, the dielectric constant at 25℃ is as high as 7600, and DF
=0.8%. This composition had a dielectric constant close to the limit for a composition to which the present invention was applied.

[Table] Example 6 Basic ceramic composition as in Example 2, using Transelco 219-6 barium titanate instead of HPBT-1, and adding a few drops of acetic acid to the ceramic strip to improve dispersion. An MLC capacitor was manufactured in the same manner as in Example 2 except for this. Examples were performed with only 1.25 and 1.50% flits. The capacitor was fired as described above and the following electrical results were obtained.

【table】

[Table] Examples 7-12 Two separate compositions were made according to the procedure of Example 2, and each was fired at three different temperatures to observe the effect of sintering temperature on electrical properties. . The composition and properties of these materials are shown in Table 1 below.

[Table] Not only the DF value but also the permittivity of dielectrics tend to decrease as the sintering temperature decreases. Example 13 The use of barium zinc niobate in the present invention will be specifically explained with reference to an example. in this case,
200 g of BaCO ₃ in isopropanol Nb ₂ O ₅ 98.80
g and 0.24 g of ZnO.
After drying, the mixed powder was calcined at 1000° C. for 5 hours in a high purity alumina crucible. It was then ground with ZrO ₂ balls to a particle size (D ₅₀ ) of 0.81 micrometers. Similarly 30%Pd-70%Ag in the previous example
A multilayer ceramic capacitor was manufactured using electrodes consisting of: The composition of the ceramic was as follows. BaTiO ₃ (Fuji HPBT-1) 82.25% by weight, PbZrO ₃ 11.0% by weight, Ba(Zn _1/3 Nb _2/3 )O ₃ 4.5% by weight, and Mn-doped zinc borate flux used in Example 2 1.25% by weight. %, when fired as in the previous example, the Curie temperature was 25
℃, the dielectric constant was 9600, and DF=3.0%. The insulation resistance exceeded 10,000ΩF.

Claims (1)

[Claims] A Curie point modifier selected from 1 a BaTiO ₃ , b A (Zn _1/3 Nb _2/3 ) O ₃ , c BaZrO ₃ , PbZrO ₃ , BaSnO ₃ , PbSnO ₃ and mixtures thereof. , and d manganese-doped metal borate flex selected from zinc borate and its mixtures and its oxide precursors with a ZnO:B ₂ O ₃ ratio of 2 to 4.
(F) consisting of a mixture of finely divided particles of
To form a densified dielectric material containing 2.5 to 11.5% by weight of b and 1.0 to 5.0% by weight of d, and in which only a is replaced by 1.5 to 12.5 mol% of c, at a low sintering temperature. Composition of. 2. A composition according to claim 1, which additionally contains 0.05 to 0.5% by weight of manganese oxide as MnO ₂ , BaMnO ₃ or their precursors. 3. The composition according to claim 1, wherein c is a mixture of PbZrO ₃ and BaZrO ₃ and d is 3ZnO.B ₂ O ₃ . 4 Up to 50 mol% of B ₂ O ₃ can be converted into SiO ₂ , GeO ₂ , Al ₂ O ₃
or a mixture thereof. 5. Claim 1, in which particles fired at 1000 to 1150°C in air are sintered to densify the mixture.
A dielectric composition consisting essentially of the composition described in 1. 6. The composition of claim 1, wherein a mixture of finely divided solids is dispersed in an organic medium containing a polymeric binder dissolved in an organic solvent. 7. The composition according to claim 6, wherein the organic solvent is a volatile non-aqueous solvent and the dispersion has a viscosity that allows casting. 8 The polymer binder is a mixture of a miscible polymer consisting of 0 to 100% by weight of a _C1 - _C8 alkyl methacrylate, 100-0% by weight of a _C1 - _C8 alkyl acrylate, and an ethylenically unsaturated carboxylic acid or amine. This multipolymer has a number average molecular weight (Mn) of 50,000 to 100,000, a weight average molecular weight (Mw) of 150,000 to 350,000, and a ratio of Mw:Mn of 5.5.
smaller, the total amount of unsaturated carboxylic acids or amines in the multipolymer mixture is 0.2-2.0% by weight
A composition according to claim 7, characterized in that the polymer and, if present, the plasticizer therein have a glass transition temperature of -30 DEG to +45 DEG C. 9. The composition according to claim 8, wherein the alkyl methacrylate is ethyl methacrylate and the alkyl acrylate is methyl acrylate. 10. The composition of claim 8, wherein the ethylenically unsaturated carboxylic acid is a monocarboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, and mixtures thereof. 11. Claims in which the organic medium is a solution containing a resin and a thixotropic agent dissolved in a solvent and has a boiling point of 130 to 350°C, and the dispersion has a paste-like viscosity suitable for screen printing. Composition according to item 6. 12. The composition of claim 7, wherein the dispersion is cast into layers, the volatile solvent is removed therefrom, and a dielectric green tape is formed.