JPH11240753A - Dielectric porcelain and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric porcelain capable of being sintered at a low temperature and capable of improving moisture resistance, and to provide a laminate. SOLUTION: This dielectric porcelain comprises perovskite type main crystal granules comprising a compound oxide containing at least Mg and Ti as metal elements and granular boundaries existing among the perovskite type main crystal granules. The granular boundaries contain B, alkali metals and Al as elements. Therein, the compound oxide comprises 100 pts.wt. of a main component containing at least Mg and Ti as metal elements and expressed by the compositional formula (based on molar ratio): (1-x)MgTiO3 .xCaTiO3 [(x) satisfies the inequality: 0<=(x)<=0.2], and B in an amount of 3-20 pts.wt. (converted into B2 O3 ), an alkali metal in an amount of 1-10 pts.wt. (converted into an alkali metal carbonate), Si in an amount of 0.01-5 pts.wt. (converted into SiO2 ), an alkaline earth metal in an amount of 0.1-5 pts.wt. (converted into an alkaline earth metal oxide) and Al in an amount of 0.01-2 pts.wt. (converted into Al2 O3 ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a dielectric porcelain,
In particular, the present invention relates to a dielectric ceramic and a laminated body having a high Q value in a high frequency region such as a microwave and a millimeter wave, and for example, various resonators and MICs used in a high frequency region such as a microwave and a millimeter wave. Dielectric substrate,
The present invention relates to a dielectric ceramic and a laminate that can be used for a dielectric waveguide, a dielectric layer of a multilayer ceramic capacitor, and the like.

[0002]

2. Description of the Related Art Hitherto, dielectric ceramics have been widely used in dielectric resonators, MIC dielectric substrates, waveguides, and the like in high-frequency regions such as microwaves and millimeter waves. In recent years, with the development and spread of mobile communication such as mobile phones, demand for dielectric ceramics as materials for electronic circuit boards and electronic components has been increasing.

[0003] When simultaneously firing dielectric ceramics and internal conductors in electronic circuit boards and electronic components, the firing temperature of conventional dielectric ceramics was as high as 1100 ° C or more, so that relatively high conductor materials were used. Melting points such as Pt, Pd, W, and Mo were used. These conductive materials having a high melting point have a large conduction resistance.
There is a problem that the value becomes small and the transmission loss of the conductor line becomes large.

In order to solve such a problem, there has been proposed a low-temperature-fired dielectric ceramic which can be co-fired with Ag, Cu or the like having a low conduction resistance. For example, a dielectric porcelain composition disclosed in Japanese Patent Application Laid-Open No. 8-208330, filed by the present applicant, is composed of MgO, CaO, TiO ₂ and B ₂ O ₃ , Li ₂ CO ₃ , 900 ~
It can be fired at a relatively low temperature of 1050 ° C. at the same time as the inner conductors such as Ag and Cu.
It has excellent characteristics such that the Q value at the measurement frequency of 7 GHz is 2000 or more and the temperature coefficient τf of the resonance frequency is within ± 40, and can realize the miniaturization and high performance of the high-frequency electronic component.

[0005]

However, the dielectric porcelain composition disclosed in Japanese Patent Application Laid-Open No. 8-208330 contains B ₂ O ₃ and Li ₂ CO ₃ as sintering aid components, so that it is resistant to moisture. There was a problem that the property is low.

[0006] That is, since _{B 2 O 3, Li 2 CO} 3 is water soluble, is _{B 2 O 3, Li 2 CO} 3 in the dielectric ceramic was dissolved in water, for example in the air, moisture in the porcelain It easily penetrates, and therefore, when used in a place with a lot of humidity or the like, there is a possibility that the insulation resistance of the dielectric porcelain decreases.

In the above dielectric porcelain, the sintering temperature is still high, and the shrinkage starting temperature in sintering is 845-96.
Since the temperature is as high as 0 ° C., the matching of the shrinkage behavior with the conductor material is poor, and there are problems such as warping and distortion of the fired substrate or electronic component.

That is, as the conductor, a conductor containing Ag and / or Cu as a main component, for example, Ag, Cu, or a glass component, a ceramic component,
There are materials to which metals such as t and Pd are added, and these conductors have a shrinkage onset temperature of 650 ° C. at the highest during firing.
Therefore, there is a large difference between the dielectric ceramic composition and the shrinkage start temperature of the dielectric ceramic composition, thereby causing a problem that the substrate or the like is deformed.

[0009] The present invention has been made in view of the above problems,
An object of the present invention is to provide a dielectric porcelain and a laminated body which can improve moisture resistance and can be fired at a low temperature, and can further lower the firing temperature than before, lower the shrinkage start temperature, and start shrinkage of the conductor. It is an object of the present invention to provide a dielectric ceramic and a laminate that can be brought close to a temperature and can suppress warpage and distortion even when co-fired with a conductor containing Ag or Cu as a main component.

[0010]

According to the present invention, there is provided a dielectric porcelain comprising:
A dielectric porcelain comprising a perovskite-type main crystal particle made of a composite oxide containing at least Mg and Ti, and a grain boundary existing between the perovskite-type main crystal particles, wherein the grain boundary contains, as an element, It contains B, an alkali metal and Al. Here, it is desirable that the grain boundaries further contain Si and an alkaline earth metal as elements.

Further, the composite oxide contains at least Mg and Ti as the metal element, a composition formula of these molar ratios, when expressed as _{(1-x) MgTiO 3 ·} xCaTiO 3, wherein x is 0 ≦ With respect to a main component satisfying x ≦ 0.2 and 100 parts by weight of the main component, B is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and alkali metal is 1 to 10 parts by weight in terms of alkali metal carbonate. , Si is 0.01 in terms of SiO ₂
5 parts by weight, 0.1 to 5 parts by weight alkaline earth metal oxide equivalent alkaline earth metal, it is desirable to further contain 0.01 to 2 parts by weight of Al in terms of Al ₂ O _3.

It is preferable that Mn is further contained in an amount of 0.1 to 3 parts by weight in terms of MnO _{2 based on} 100 parts by weight of the main component.

[0013] The laminate of the present invention is a laminate having a conductor containing Ag and / or Cu as a main component inside and / or on a surface of a dielectric substrate formed by laminating a plurality of dielectric layers. The body layer is made of the above-mentioned dielectric porcelain.

[0014]

In the dielectric porcelain of the present invention, at least Mg and T
Since perovskite-type main crystal grains composed of a composite oxide containing i contain B, an alkali metal and Al as elements at the grain boundaries, a perovskite-type main crystal composed of a composite oxide containing Mg and Ti Low-temperature baking at 1050 ° C. or less can be performed without significantly deteriorating the intrinsic Q value of the particles, and moisture resistance can be improved by the inclusion of Al as an element. This is presumably because the inclusion of the Al element in the porcelain strengthens the interatomic interaction with other elements and suppresses eluting components.

Further, by containing Si and alkaline earth metal in addition to B, alkali metal and Al as elements in the grain boundary phase, low-temperature firing at 950 ° C. or lower is possible and shrinkage is achieved. The starting temperature can be set to 850 ° C. or less, and there is no deformation even when co-firing with an internal conductor such as Ag or Cu.

[0016] Then, when expressed composite oxide, the composition formula by molar ratio _{(1-x) MgTiO 3 ·} xCaTiO 3, a main component x satisfies 0 ≦ x ≦ 0.2, the main component By containing a predetermined amount of B, alkali metal, Si, alkaline earth metal and Al with respect to 100 parts by weight,
The relative dielectric constant is 18 to 20, and the Qf value represented by the product of the Q value and the measured frequency is 15000 [GHz] or more;
The firing temperature is set to 950 ° C. or lower, and the shrinkage starting temperature is set to 85.
The temperature can be set to 0 ° C. or lower. Furthermore, by containing Al, the moisture resistance of the dielectric porcelain is improved, and the insulation resistance of the dielectric porcelain does not decrease even when left unattended during the humidification. It can also be positively adopted for the use of.

Further, based on 100 parts by weight of the main component,
Furthermore, the sinterability of the dielectric ceramic can be improved by containing a predetermined amount of Mn.

Further, by forming a laminated body using the above-described dielectric porcelain, even if a conductor containing Ag and / or Cu as a main component is used as the internal conductor, the laminated body is not deformed and has a high performance. A high-frequency substrate and a high-frequency component having dielectric characteristics, low-temperature firing, and good moisture resistance can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric porcelain of the present invention contains B, alkali metal and Al as elements at the grain boundaries of at least perovskite-type main crystal grains composed of a composite oxide containing Mg and Ti. Things. At least M
Perovskite-type main crystal particles composed of a composite oxide containing g and Ti include MgTiO ₃ particles. It is desirable that the grain boundaries further contain Si and alkaline earth metal as elements.

The dielectric porcelain of the present invention has a composition formula of (1-x) MgTiO ₃ .xCa
When represented as TiO _3, with respect to a main component in which x satisfies 0 ≦ x ≦ 0.2 and 100 parts by weight of the main component, B is converted to B ₂ O ₃
3 to 20 parts by weight in terms of conversion, 1 to 10 parts by weight in terms of alkali metal in terms of alkali metal carbonate, and 0.1 in terms of SiO _{2 in} terms of SiO ₂ .
01 to 5 parts by weight, 0.1 to 5 parts by weight of alkaline earth metal in terms of alkaline earth metal oxide, and Al to Al ₂ O
Desirably, the content is 0.01 to 2 parts by weight in terms of ₃ .

Here, the main component of the dielectric porcelain of the present invention is
The composition formula based on the molar ratio is expressed as (1-x) MgTiO ₃ .xCa
The reason that x satisfies 0 ≦ x ≦ 0.2 when expressed as TiO ₃ is that when x exceeds 0.2 mol, the temperature coefficient τf of the resonance frequency becomes too large on the plus side. Because. In particular, from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic, x is preferably 0.05 ≦ x ≦ 0.10. In MgTiO ₃ and CaTiO ₃ , M
If the g / Ti ratio or the Ca / Ti ratio is in the range of 0.9 to 1.1, it can be used as a main component of the composition of the present invention.

In the dielectric porcelain of the present invention, the main component 1
B is ₃ to 20 parts by weight in terms of B ₂ O ₃ and alkali metal is 1 to 10 parts by weight in terms of alkali metal carbonate with respect to 00 parts by weight.
Parts by weight, Si is 0.01 to 5 parts by weight in terms of SiO ₂ , and alkaline earth metal is 0.1 in terms of alkaline earth metal oxide.
5 parts by weight, further 0.01 of Al in terms of Al ₂ O ₃
It contains 2 parts by weight.

The reason why B is contained in an amount of 3 to 20 parts by weight in terms of B ₂ O ₃ is that when the B-containing compound is less than 3 parts by weight, it does not sinter even at 1100 ° C. and contains Ag or Cu as a main component. When it exceeds 20 parts by weight, the proportion of the glass phase in the sintered body increases,
This is because the Q value decreases. Therefore, maintaining sinterability,
From the viewpoint of obtaining a high Q value, 7 to 17 in terms of B ₂ O ₃
It is desirable to contain it by weight. As the B-containing compound, metallic boron, B ₂ O ₃ , cholemite, CaB ₂ O ₄ ,
Examples include borosilicate glass, alkali borosilicate glass, and alkaline earth borosilicate glass.

The reason that the alkali metal is contained in an amount of 1 to 10 parts by weight in terms of an alkali metal carbonate is that if the content is less than 1 part by weight, it does not sinter even at 1100 ° C.
This is because simultaneous sintering with a conductor containing u as a main component cannot be performed, and when it exceeds 10 parts by weight, the crystal phase changes and the Q value decreases. 3 to 8 from the viewpoint of the Q value of dielectric porcelain
Parts by weight are desirable. Li, N as the alkali metal
a and K can be exemplified, and among them, Li is particularly desirable. Examples of the alkali metal-containing compound include the above-mentioned alkali metal carbonates and oxides.

Further, Si is converted to SiO ₂ in the range of 0.01 to
The reason for adding 5 parts by weight is that when the content is less than 0.01 parts by weight, the shrinkage starting temperature in the sintering process of the dielectric ceramic is higher than 850 ° C., and the effect of addition cannot be obtained. On the other hand, if it exceeds 5 parts by weight, the relative dielectric constant εr or Q
This is because the value decreases. From the viewpoint of the relative permittivity εr or Q value of the dielectric ceramic, 0.5 to 3 parts by weight is desirable. S
Examples of the i-containing compound include SiO ₂ , MgSiO _3, etc. Further, the compound containing 0.1 to 5 parts by weight of an alkaline earth metal in terms of an alkaline earth metal oxide. These are 0.
If the amount is less than 1 part by weight, the shrinkage starting temperature in the sintering process of the dielectric ceramic is higher than 850 ° C., and the effect of addition cannot be obtained. On the other hand, if it exceeds 5 parts by weight, the temperature coefficient τf of the resonance frequency of the dielectric ceramic becomes too large on the plus side. In particular, from the viewpoint of the sinterability of the dielectric ceramic and the temperature coefficient τf of the resonance frequency, the total amount is preferably 0.5 to 3.5 parts by weight.

As the alkaline earth metal, Mg, Ca,
There are Sr and Ba, of which Ba is desirable. Examples of the alkaline earth metal-containing compound include carbonates and oxides of the above alkaline earth metals.

Further, Al is converted to Al ₂ O ₃ by 0.01.
２2 parts by weight. This means that Al is converted to Al ₂
When the amount is less than 0.01 part by weight in terms of O ₃ , the weight reduction rate of the sintering aid before and after the steam pressurization test (PCT) is high with respect to the moisture resistance of the dielectric porcelain, and the addition effect cannot be obtained. Because. On the other hand, if it exceeds 2 parts by weight, the Q value of the dielectric ceramic decreases. In terms of the Q value of the dielectric ceramic, the Al Al ₂ O ₃ 0.5~1.5 parts by weight in terms of desirable.

Further, in the dielectric porcelain of the present invention, from the viewpoint of improving sinterability, it is desirable that Mn is further contained in an amount of 0.1 to 3 parts by weight in terms of MnO ₂ with respect to 100 parts by weight of the main component. . When Mn is contained in an amount of 0.1 to 3 parts by weight in terms of MnO ₂ , the effect of adding Mn is small when the amount is less than 0.1 part by weight, and the dielectric properties deteriorate when the amount is more than 3 parts by weight. Because you do. Mn is desirably contained in an amount of 1.2 to 1.8 parts by weight in terms of MnO ₂ .

The dielectric porcelain of the present invention comprises
For example, MgTiO ₃ powder, CaTiO ₃ powder, and B ₂
O ₃ powder, Li ₂ CO ₃ powder, SiO ₂ powder, alkaline earth metal oxide powder (MgO, CaO, SrO, Ba
O), Al ₂ O ₃ powder, and MnO ₂ powder are prepared, weighed so as to have the above composition ratio, pulverized and mixed with a ZrO ₂ ball, and calcined the mixed powder at 650 to 850 ° C. Again with ZrO ₂ balls to reduce the particle size to 2.
This calcined powder is molded into a predetermined shape by a known method such as press molding or a doctor blade method, and is heated to 950 ° C. in a non-oxidizing atmosphere such as an air atmosphere, an oxygen atmosphere, or a nitrogen atmosphere. 0.5 below
It is obtained by firing for ~ 2 hours.

As the raw material powder, a metal salt such as a hydroxide, a carbonate, a nitrate or the like, which forms an oxide upon firing, may be used.

It is desirable to add the alkaline earth metal as a glass frit from the viewpoint of improving sinterability. For example, B ₂ O ₃ powder, Li ₂ CO ₃ powder, SiO ₂ powder,
A glass frit is prepared and added using an alkaline earth metal oxide powder. At this time, B ₂ O ₃ powder, Li ₂ CO ₃
Needless to say, the amount added as the ₃ powder and the SiO ₂ powder is an amount obtained by subtracting the amount used for the glass frit.

In the dielectric porcelain of the present invention, Zr or the like may be mixed in the production process such as the step of mixing and pulverizing the raw materials, or Fe, Hf, Sn or the like may be contained as inevitable impurities of the raw materials.

In the dielectric porcelain of the present invention, MgTiO ₃ is used as main crystal particles, and CaTiO ₃ may be precipitated on the main crystal particles. Further, (Mg, Ti) ₂ (BO ₃ ) O may be precipitated.

Incidentally, the alkaline earth metal dissolves in the A site of MgTiO ₃ and CaTiO ₃ or becomes a glass to improve the sinterability. Also, S
i and Al exist as glass. The alkali metal is dissolved in the main crystal phase or exists as glass at the grain boundary.
B, alkali metals, Al, Si and alkaline earth metals are mostly present as glass. The dielectric porcelain of the present invention has an average crystal grain size of 1 to 5 μm.

[0035]

EXAMPLE As a raw material, MgTiO _{3 having a} purity of 99% or more was used.
Powder, CaTiO ₃ powder, B ₂ O ₃ powder, alkali metal (Li, Na, K) powder, SiO ₂ powder, alkaline earth metal (MgO, CaO, SrO, BaO) powder, Al ₂
The O ₃ powder and the MnO ₂ powder were weighed so as to have the ratios shown in Table 1 and wet-mixed with pure water as a medium in a ball mill using ZrO ₂ balls for 20 hours.

Next, the mixture is dried (dehydrated) and
Calcination was performed at ℃ for 1 hour. This calcined product was ground to a pulverized particle size of 1.4.
μm or less, and pressed as a sample for evaluation into a column having a diameter of 10 mm and a height of 8 mm at a pressure of 1 ton / cm ² , and baked at a temperature shown in Table 2 for 2 hours. A columnar sample having a height of 6 mm was obtained. At this time, the shrinkage onset temperature was measured by measuring the heat shrinkage.

For the evaluation of the dielectric properties, the relative permittivity and the Q value at a frequency of 8 GHz were measured using the sample by the dielectric cylinder resonator method. Table 2 shows the value represented by the product of the Q value and the measurement frequency f. Further, the temperature coefficient τf of the resonance frequency in the temperature range of −40 to + 85 ° C. [ppm / ° C.]
Was measured.

As the evaluation of moisture resistance, sintering aid components excluding the main components of each sample, ie, B ₂ O ₃ powder, alkali metal (Li, Na, K) powder, SiO ₂ powder, alkaline earth metal (MgO, CaO, SrO, BaO) powder, Al
_A steam pressurization test (PCT) was performed on a mixed powder of ₂ O ₃ powder fired at 650 ° C. for 10 minutes in the air at 121 ° C.
At a temperature of 2 atm, under unsaturated conditions for 24 hours,
The weight loss rates before and after the steam pressurization test were measured and are shown in Table 2. A product of the present invention having a weight reduction rate of 0.4% by weight or less was defined as the product of the present invention.

Note that the present inventors have conducted X-ray diffraction measurement and X-ray diffraction measurement.
It was confirmed by a line microanalyzer (EPMA) that the main crystal particles were MgTiO ₃ in the sample of the present invention, and that B, alkali metal, Al, Si and alkaline earth metal were present as elements at the grain boundaries.

[0040]

[Table 1]

[0041]

[Table 2]

From these Tables 1 and 2, it can be seen that when Al is contained, the moisture resistance is excellent, and when B or an alkali metal is contained, low-temperature firing at 1050 ° C. or less is possible. . In particular, when the composition formula of the present invention is satisfied, the relative dielectric constant is 18 to 20, and the Qf value is 15000 [GH
z], the temperature coefficient τf of the resonance frequency is ± 40 ppm /
It has excellent dielectric properties within ℃, sintering shrinkage starts at 850 ℃ or less, it can be fired at 950 ℃ or less, has excellent sinterability, and has high moisture resistance. . Sample No. 2, which does not contain Si and alkaline earth metal, has a good sintering temperature of 1020 ° C. and good moisture resistance, but has a slightly higher shrinkage onset temperature.

On the other hand, in Sample No. 1 containing no Al, the moisture resistance was poor, and as the Al content was increased, the moisture resistance was improved. In particular, the content in terms of Al ₂ O ₃ was 0.5 parts by weight or more. It can be seen that at the time of (Sample No. 5), the moisture resistance becomes the best. Further, B, the sample No. containing no alkali metal.
10 indicates that the firing temperature was as high as 1200 ° C.

In Table 1, BaO-CaO in the column of alkaline earth metal means that the weight ratio of BaO to CaO is 1: 1.
Is a mixture of

[0045]

As described above in detail, according to the present invention, a piezoelectric ceramic which can be fired at a low temperature and has excellent moisture resistance can be obtained. In particular, when B, an alkali metal, Al, Si, and an alkaline earth metal are contained, the firing temperature can be 950 ° C. or less, the shrinkage onset temperature can be 850 ° C. or less, and a conductor metal such as Ag or Cu can be used. It can be fired at the same time, and in this case, the warpage and distortion of the substrate caused by the mismatch of the shrinkage behavior of the conductive metal are suppressed, and it has a high dielectric constant and Q value in a high frequency region, and good moisture resistance, so that electronic components and substrates The size and performance can be improved.

Claims (5)

[Claims] 1. A dielectric ceramic comprising a perovskite-type main crystal particle comprising a composite oxide containing at least Mg and Ti, and a grain boundary existing between the perovskite-type main crystal particles. A dielectric porcelain characterized by containing B, an alkali metal and Al as elements in a field. 2. The dielectric ceramic according to claim 1, wherein the grain boundary further contains Si and an alkaline earth metal as elements. 3. A composite oxide contains at least Mg and Ti as the metal element, a composition formula of these molar ratios, when expressed as _{(1-x) MgTiO 3 ·} xCaTiO 3, wherein x is 0 ≦ With respect to a main component satisfying x ≦ 0.2 and 100 parts by weight of the main component, B is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and alkali metal is 1 to 10 parts by weight in terms of alkali metal carbonate. , Si is 0.01 in terms of SiO ₂
5 parts by weight, wherein characterized in that it contains 0.01 to 2 parts by weight from 0.1 to 5 parts by weight of an alkaline earth metal in terms of oxide of an alkali earth metal, a further Al in terms of Al ₂ O ₃ with Item 3. The dielectric porcelain according to item 1 or 2. 4. Mn is added to 100 parts by weight of a main component.
The dielectric ceramic according to claim 3, characterized in that it contains 0.1 to 3 parts by weight MnO ₂ basis. 5. A laminate having a conductor containing Ag and / or Cu as a main component inside and / or on a surface of a dielectric substrate formed by laminating a plurality of dielectric layers. Item 5. A laminate comprising the dielectric porcelain according to any one of Items 1 to 4.