JPH1067557A - Production of dielectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a dielectric porcelain composition, enabling to suitably produce a laminated dielectric porcelain by a wet molding method, by using a powdery raw material low in surface activity and obtained by thermally treating a powdery main dielectric porcelain material such as a Ba-Ti-Nb-O system material and glass powder at a sintering temperature or below. SOLUTION: This method for producing a dielectric porcelain composition comprises mixing a main powdery component comprising a dielectric porcelain material with a powdery auxiliary component containing glass powder, and subsequently thermally treating the mixture at a temperature from the melting point of the glass powder to its sintering temperature to produce the powdery material in which the auxiliary component is adhered to the main component particles. The powdery material is useful as a material suitable for producing dielectric materials, especially laminated dielectric porcelain devices having Ag or Cu electrodes and produced by simultaneously sintering at low temperatures, such as laminated chip capacitors and laminated dielectric resonators. The content of the main component is 1.5-39wt.% based on the content of the auxiliary component. The main component includes a Ba-Ti-rare earth element system dielectric material, an Al-titania-Ba-Ti system dielectric material and a Ba-Mg-Ta system dielectric material. The glass powder includes PbO-ZnO-B2 O3 glass powder and PbO-B2 O3 -ZnO-GeO glass powder. The material powder is molded by a wet type method and subsequently laminated to electrodes to form various kinds of laminated elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a dielectric ceramic composition suitable as a material for a dielectric resonator or the like.

[0002]

2. Description of the Related Art Recently, multilayer chip capacitors, multilayer dielectric resonators and the like in which a dielectric ceramic composition is laminated have been developed, and lamination by simultaneous firing of the ceramic composition and internal electrodes has been performed. Inexpensive silver (Ag) as this electrode material,
In order to use silver-palladium (Ag-Pd) and copper (Cu), various dielectric ceramic compositions that can be co-fired at a low temperature of 1200 ° C. or less have been proposed.

[0003]

In these porcelain compositions, in order to enable sintering at a low temperature, a glass powder having a low melting point is added as an auxiliary component, or the material powder of the porcelain composition is finely pulverized. Things have been done. However, these material powders have a high activity on the particle surface and easily adsorb moisture and the like, so that the process control in the non-aqueous wet molding is very difficult. On the other hand, if the specific surface area is large, a large amount of the organic binder component is required at the time of molding, and the binder removal step becomes complicated. For this reason, there is a demand for a material powder of a porcelain composition having low surface activity and a small specific surface area of the particles and capable of being sintered at a low temperature.

Further, these dielectric ceramic compositions are required to have characteristics such as a large relative permittivity ε _r , a large unloaded Q, and a small temperature coefficient τ _f of the resonance frequency. .

[0005] An object of the present invention is to provide a dielectric resonator or the like which has excellent properties, has low surface activity of particles, and is used for producing a dielectric ceramic composition which can be fired at a low temperature simultaneously with an internal electrode. It is to provide a material powder having a small specific surface area.

[0006]

According to the present invention, there is provided a method for producing a dielectric ceramic composition comprising a main component and a subcomponent including glass powder, wherein the material powder of the dielectric ceramic composition is
After mixing the main component particles and the subcomponent, the subcomponent was attached to the main component particles obtained by heat treatment at a temperature higher than the softening point of the glass powder in the subcomponent and lower than the sintering temperature. The present invention relates to a method for producing a dielectric porcelain composition, characterized by using a material powder.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the dielectric ceramic composition according to the present invention, the content a (% by weight) of the subcomponent with respect to the main component depends on the ratio of the glass powder in the subcomponent. If the amount a is excessively small, it becomes difficult to uniformly coat the main component particles with the subcomponents,
Since low-temperature sintering at a temperature of 200 ° C. or less becomes difficult, and if the amount is excessively large, the unloaded Q may be reduced, the content a may be in the range of 1.5 ≦ a ≦ 39. preferable.

[0008] As the main component of the dielectric ceramic composition of the present invention is not particularly limited, for example, barium - titanium - include a dielectric ceramic composition having a high dielectric constant epsilon _r as rare earth And various dielectric ceramic compositions such as perovskites such as alumina, titania, barium-titanium, and barium-magnesium-tantalum.

Representative examples of the main components of these dielectric ceramic compositions include dielectric ceramic compositions comprising barium, titanium, neodymium and oxygen. Further, 0 to 75 mol% of neodymium in the main component of the dielectric ceramic composition can be replaced with another rare earth element such as samarium.

Further, in order to obtain a dielectric ceramic composition having desired electric characteristics, or to lower the sintering temperature or to improve the sinterability, bismuth, vanadium, antimony, manganese, lanthanum, lead, Zirconia, tin,
Yttrium or the like can be added. As the raw material constituting the main component, a raw material such as an oxide containing the constituent element can be used as it is, or calcined powder can also be used. If the particle diameter of the main component particles is excessively large, the sintering temperature becomes high, and simultaneous sintering with the electrode may become difficult.If the particle diameter is excessively small, the specific surface area increases, and a large amount of the organic binder component is formed during molding. This is necessary, and the binder removal step may be complicated. Therefore, the average particle size of the main component particles is preferably about 0.1 to 30 μm.

[0011] A dielectric ceramic composition having good electrical characteristics and capable of being fired at a low temperature can be provided by adding a sub-component including glass powder to the main component. As the glass powder contained in the subcomponent, a glass powder having a softening point of usually 150 to 1000 ° C. is used. For example, a glass powder composed of PbO, ZnO and B ₂ O ₃ , SiO ₂ and B ₂ O glass powder composed of _3, was added PbO, B ₂ O _3, ZnO and glass powder composed of GeO _2, or oxides and / or alkaline earth metal oxides of the alkali metal element to the system Such systems can be mentioned.

Further, as the sub-component, for example, GeO ₂ , L
i ₂ O and the like can be mentioned. Further, Ag, SiO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , C
aCO ₃ , BaCO ₃ , MgO, ZnO, CuO and the like can be contained.

When a glass powder composed of PbO, ZnO and B ₂ O ₃ is used as an auxiliary component,
If the amount used is excessively large, the no-load Q may decrease, so that the content b (% by weight) of the glass powder with respect to the main component is preferably 1 ≦ b ≦ 25. In this case, the composition ratios of PbO, ZnO and B ₂ O ₃ are not particularly limited. However, if the content of ZnO is excessively large, the softening point of the glass increases, and low-temperature firing may become difficult. The content of ZnO in the glass powder is 50% by weight
The following is preferred.

When GeO ₂ is used as a sub-component, if the amount is excessively large, the no-load Q may be reduced. Therefore, the content c (% by weight) of the sub-component GeO ₂ with respect to the main component. Is preferably 0.5 ≦ c ≦ 10. Further, when Li ₂ O is used as a sub-component, the content d (% by weight) of the sub-component Li ₂ O with respect to the main component is preferably 0.04 ≦ d ≦ 4. When Ag is contained as a sub-component, the content e (% by weight) of Ag with respect to the main component is preferably 5% by weight or less.

The heat treatment temperature depends on the type of glass powder and the type of dielectric ceramic composition contained in the auxiliary component, but is higher than the softening point of the glass powder to be used and the temperature of the dielectric ceramic composition. The temperature is not particularly limited as long as it is lower than the sintering temperature of the raw material powder.

When the heat treatment temperature is lower than the softening point of the glass powder in the subcomponent, the raw material powder of the main component does not adhere to the particle surface, the surface activity of the particle is high, and the specific surface area is large. On the other hand, when the temperature is higher than the sintering temperature, the sinterability deteriorates. The heat treatment is preferably performed at the above temperature for 0.1 to 20 hours. By melting the glass powder by performing the heat treatment, it is possible to obtain a material powder in which the subcomponent is uniformly adhered to the particle surface of the raw material powder of the dielectric ceramic composition.

In particular, a calcined powder composed mainly of barium, titanium, neodymium and oxygen, and PbO and ZnO as subcomponents
Powder comprising Ge and B ₂ O ₃ and Ge
Manufacture of dielectric porcelain composition using material powder obtained by heat-treating O ₂ and Li ₂ O at 300 to 800 ° C., preferably 400 to 600 ° C., obtained by attaching subcomponents to main component particles The relative permittivity ε _r and the unloaded Q
Is excellent, and excellent dielectric characteristics with a small temperature coefficient τ _f of the resonance frequency can be obtained.

In the case of a dielectric porcelain composition whose main component is composed of barium, titanium, neodymium and oxygen, the composition formula:
When expressed as _{xBaO-yTiO 2 -zNd 2 O 3} ,
x, y and z are respectively 0.1 ≦ x ≦ 0.2, 0.
5 ≦ y ≦ 0.8, 0.1 ≦ z ≦ 0.3 (x + y
+ Z = 1. ) Is desirable.

At this time, the main component xBaO-yTiO ₂ -z
When the molar fraction x of BaO in Nd ₂ O ₃ is excessively large, resonance does not occur. When the molar fraction x is excessively small, the dielectric constant and the no-load Q decrease. If the molar fraction y of TiO ₂ is excessively large, the temperature coefficient of the resonance frequency increases, and if it is excessively small, the dielectric constant decreases. N
If the molar fraction z of d ₂ O ₃ is too large, the relative permittivity ε _r and the unloaded Q will be small, and if it is too small, the temperature coefficient of the resonance frequency will be large.

An example of the method for producing the dielectric ceramic composition of the present invention will be described below. The starting materials of barium carbonate, titanium oxide, and neodymium oxide are wet-mixed in predetermined amounts with a solvent such as water or alcohol. Subsequently, after removing water, alcohol and the like, the mixture is pulverized and calcined in an oxygen-containing gas atmosphere (for example, an air atmosphere) at 1000 to 1300 ° C. for about 1 to 10 hours. Obtained calcined powder of main component and subcomponents PbO, Z
Glass powder (softening point: 300 ° C.) composed of nO and B ₂ O _{3 is} wet-mixed and pulverized with a solvent such as alcohol. Subsequently, after removing alcohol or the like, the temperature is set to 350 ° C. to 500 ° C. in an oxygen-containing gas atmosphere (for example, an air atmosphere).
Heat treatment at about 1 to 10 hours. The obtained material powder is mixed with an organic binder such as polyvinyl butyral and a plasticizer such as dibutyral phthalate, and wet-molded by a doctor blade method or the like to obtain a dielectric ceramic composition molded body.

The dielectric ceramic composition molded body thus obtained can be used as a material for a dielectric resonator, a dielectric substrate, a laminated element, and the like by laminating with an electrode. In addition, as a raw material of barium, titanium, and neodymium, BaCO ₃ ,
In addition to TiO ₂ and Nd ₂ O ₃ , nitrates and hydroxides that become oxides during firing can be used.

[0022]

The present invention will be described more specifically with reference to the following examples. Example 1 Barium carbonate (BaCO ₃ ) 0.17 mol, titanium oxide (TiO ₂ ) 0.66 mol, neodymium oxide (Nd
₂ O ₃₎ 0.17 mol were placed in a ball mill together with ethanol and mixed for 12 hours wet. After desolvating the solution, pulverize,
It was calcined at 1250 ° C. in an air atmosphere. 25% by weight of glass powder (softening point: 300 ° C.) composed of sub-components PbO, ZnO and B ₂ O _{3, 3} % by weight of germanium oxide (GeO ₂ ) and lithium carbonate (Li) ₂ CO ₃ ) 1% by weight (0.4% by weight in terms of Li ₂ O) was added, and put into a ball mill together with ethanol.
Wet mixed for 48 hours. After removing the medium, the resultant was pulverized and heat-treated at 400 ° C. for 1 hour in an air atmosphere. Polyvinyl butyral (hereinafter abbreviated as PVB) and dibutyral phthalate (hereinafter abbreviated as DBP) were added to the obtained material powder, and mixed in a toluene and isopropyl alcohol solvent to obtain a slurry. This slurry is subjected to wet molding by a doctor blade method, and is laminated on pellets having an inner diameter of 12 mmφ and a thickness of 4 mmt using Ag as an internal electrode,
Sintering was performed at 875 ° C. in an air atmosphere to obtain a laminate having good sinterability.

Examples 2 to 5 Laminates were made in the same manner as in Example 1 except that the heat treatment temperature was changed as shown in Table 1, and the optimum sintering temperature was determined. Table 1 shows the heat treatment temperature and the optimum sintering temperature. Heat treatment temperature is 90
When the heat treatment is performed at 0 ° C., which is higher than the sintering temperature before the heat treatment (825 to 875 ° C.), the optimum sintering temperature is 97 ° C.
The temperature was raised to 5 ° C., and the silver as the internal electrode was altered.
In addition, when the heat treatment was not performed, the surface activity of the particles was high, the water absorption was high, the process control during non-aqueous wet molding was complicated, and a large amount of the organic binder component was required during molding. .

Examples 6-12 PVB, D for heat treatment temperature and obtained material powder
A material powder was prepared in the same manner as in Example 1 except that the amount (% by weight) of BP was changed as shown in Table 2, and the water absorption and
The specific surface area was measured. Further, PVB and D shown in Table 2
Wet molding was performed with the amount of BP, and the moldability was determined. Table 2 shows the results. In the column of wet moldability in Table 2, ○ indicates that a good molded body can be obtained, △ indicates that molding is possible, but process control during molding is difficult, and × indicates that molding is impossible. Is shown.

As shown in Table 2, when the heat treatment was performed at 600 ° C. as compared with the case where the heat treatment was not performed or the case where the heat treatment was performed at a temperature equal to or lower than the softening point (300 ° C.).
(Adsorption amount when left for 1 hour in an atmosphere of 5 ° C and 65% humidity)
Is reduced to 0.04%, the activity of the particle surface is reduced,
The specific surface area ratio (the specific surface area without heat treatment is 1
), The binder amount required during the wet molding is reduced, and the wet moldability is improved.

Examples 13 to 23 The mixing ratios of barium carbonate, titanium oxide and neodymium oxide in Example 1 and PbO, ZnO and B ₂ O
Glass powder composed of ₃ , GeO ₂ and Li ₂ O
A dielectric ceramic composition was produced in the same manner as in Example 1 (heat treatment temperature: 400 ° C.) except that the amount of addition was changed as shown in Table 3 and the obtained ceramic composition was 7 mm in diameter and 7 mm in thickness. 3
After processing to the size of mmt, the dielectric constant was measured by the dielectric resonance method, and the relative permittivity ε _r at the resonance frequency (3 to 6 GHz), the no-load Q, and the temperature coefficient τ _f of the resonance frequency were obtained. Table 3 shows the wet moldability. It can be seen that a good molded body can be obtained by performing the heat treatment.

[0027]

According to the present invention, Ag, Ag-Pd, C
It can be sintered at a low temperature at the same time as the internal electrodes such as u, and the surface activity of the particles of the material powder used in producing the dielectric ceramic composition is low, and the specific surface area is small, so that the wet formability is excellent. Thus, a laminate of the dielectric ceramic composition can be suitably manufactured.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

Claims (8)

[Claims] 1. A method for producing a dielectric porcelain composition comprising a main component and a sub-component containing glass powder, wherein the main component particles and the sub-component are mixed as a material powder of the dielectric porcelain composition. Dielectric porcelain characterized by using a material powder obtained by heat-treating at a temperature higher than the softening point of the glass powder in the sub-component and lower than the sintering temperature, wherein the sub-component is attached to the main component particles. A method for producing the composition. 2. The dielectric ceramic composition according to claim 1, wherein the content a (% by weight) of the subcomponent with respect to the main component is 1.5 ≦ a ≦.
The method for producing a dielectric ceramic composition according to claim 1, wherein the composition is 39. 3. The method for producing a dielectric ceramic composition according to claim 1, wherein the main component of the dielectric ceramic composition comprises barium, titanium, neodymium, and oxygen. 4. The dielectric ceramic composition, wherein the main component is a composition formula, xBaO-yTiO ₂ -zNd ₂ O ₃ (where 0.1 ≦ x ≦ 0.2, 0.5 ≦ y ≦ 0. 8, 0.1
≦ z ≦ 0.3, x + y + z = 1. The method for producing a dielectric ceramic composition according to claim 1, wherein 5. The method for producing a dielectric ceramic composition according to claim 1, wherein the glass powder contained in the auxiliary component is a glass powder composed of PbO, ZnO and B ₂ O ₃ . 6. The method according to claim 1, wherein the auxiliary component is glass powder or Ge.
_{2. The method according} to claim 1, wherein the material comprises O ₂ and Li ₂ O.
A method for producing the dielectric ceramic composition according to the above. 7. The method according to claim 1, wherein the sub-components are PbO, ZnO and B
Glass powder consisting of ₂ O ₃ and GeO ₂ and Li ₂
The method for producing a dielectric ceramic composition according to claim 1, comprising O. 8. The content b (% by weight) of the glass powder composed of PbO, ZnO and B ₂ O ₃ is 1 ≦ b ≦ 25, and
O ₂ content c (weight%) is 0.5 ≦ c ≦ 10, Li ₂
8. The method for producing a dielectric ceramic composition according to claim 7, wherein the O content d (% by weight) satisfies 0.04 ≦ d ≦ 4.