JP3411190B2 - Dielectric porcelain composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition suitable for use in a microwave region and capable of being fired at a low temperature, in particular, a plurality of dielectric layers are laminated, and a silver layer is provided between the dielectric layers. Also, the present invention relates to a dielectric ceramic composition suitable for a laminated body having an internal conductor containing copper as a main component, for example, electronic components such as a resonator, a capacitor, a filter, and a substrate containing them.

[0002]

2. Description of the Related Art Conventionally, various dielectric ceramics have been widely used as a dielectric material in electronic circuit boards, electronic parts, etc., and in recent years, they have become popular in the development and popularization of high frequency equipment such as mobile communication represented by a mobile phone. Along with this, dielectric ceramics have been actively used as electronic circuit boards and electronic components used in the high frequency region.

Conventionally, M has been used as a dielectric ceramic composition having a low dielectric loss (high Q value) and a small temperature coefficient of resonance frequency.
A porcelain composition having a three-component composition of gO / CaO / TiO ₂ is known. This composition has a relative dielectric constant of about 20 and 7 to 8
It has excellent dielectric properties such that the Q value at GHz is about 8000 and the temperature coefficient τf of the resonance frequency is near 0.

However, this composition needs to be sintered at a high temperature of 1300 ° C. or higher, and when this material is used as a laminated body, for example, a dielectric ceramic for a resonator, the conductor forming the pattern is the above-mentioned dielectric. It is necessary to use palladium (melting point 1555 ° C.), which is an expensive noble metal that does not melt at the sintering temperature of the porcelain and does not oxidize, or an alloy thereof, which causes a problem of high cost.

Therefore, it is known that a boron-containing compound and a lithium-containing compound are added to a three-component composition of MgO, CaO, and TiO ₂ to achieve low temperature firing at 900 to 1050 ° C (special characteristics). Kaihei 8-208330).

[0006]

However, the dielectric ceramic composition disclosed in the above-mentioned Japanese Patent Laid-Open No. 8-208330 has a boron-containing compound and a lithium-containing compound added thereto, so that it can be used as a conductor simultaneously with an electrode material such as Ag or Cu. Although it can be fired, there is a problem that a sufficient Q value cannot be obtained.

The present invention has been made in view of the above problems,
It has the features that it can be fired at the same time as an internal conductor such as Ag or Cu at a relatively low temperature of 900 to 1050 ° C, has a high relative permittivity εr, has a relatively small temperature coefficient τf of resonance frequency, and has a sufficiently high Q value. However, it is an object of the present invention to provide a dielectric ceramic composition that can realize miniaturization and high performance of high-frequency electronic components and substrates.

[0008]

The dielectric porcelain composition of the present invention is a composite oxide containing Mg, Ca, and Ti as metal elements, and the composition formula based on the weight ratio of these metal element oxides is shown. When expressed as aMgO · bCaO · cTiO ₂ , the above a, b, c are 25.0 ≦ a ≦ 35.0, 0.3
≤ b ≤ 7.0, 60.0 ≤ c ≤ 70.0, a + b + c
= Main component which satisfies the 100, with respect to the main component 100 parts by weight, 1 to 10 weight boron-containing compound from 3 to 20 parts by weight terms _of B ₂ O _3, the alkali metal-containing compound with an alkali metal carbonate terms Part, at least one kind of Sn-containing compound and Zr-containing compound in total of 0.3 to oxide equivalent.
It is characterized by containing 3.5 parts by weight.

The dielectric porcelain composition of the present invention is a composite oxide containing Mg, Ca, and Ti as metal elements, and its composition formula is (100-x) MgTiO ₃ -xC.
aTiO ₃ (where x represents a weight ratio, 1 ≦ x ≦ 1
5) a main component represented by, with respect to the main component 100 parts by weight, 3 to 20 parts by weight of a boron-containing compound in terms _of B ₂ O _3,
1 for alkali metal-containing compound in terms of alkali metal carbonate
-10 parts by weight, at least one kind of Sn-containing compound and Zr-containing compound in total of 0.3 to 3.5 in terms of oxide.
It is characterized by containing parts by weight.

[0010]

In the dielectric ceramic composition of the present invention, 900 to 10
It can be fired at a relatively low temperature of 50 ° C at the same time as a conductor metal mainly composed of Ag, Cu, etc., and has a relative permittivity εr or Q of a dielectric ceramic.
The value is high, the temperature coefficient τf of the resonance frequency can be made relatively small, and the high-frequency electronic circuit board and electronic parts can be downsized and the performance can be improved.

Particularly, in the dielectric ceramic composition of the present invention, S
At least one of n-containing compound and Zr-containing compound
Since the total amount of the seeds is 0.3 to 3.5 parts by weight in terms of oxide, the Q value can be greatly improved as compared with the case where these are not contained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric ceramic composition of the present invention is a composite oxide containing Mg, Ca, and Ti as metal elements, and the composition formula based on the weight ratio of these metal element oxides is aMgO. When expressed as bCaO · cTiO ₂ , a,
b and c are 25.0 ≦ a ≦ 35.0 and 0.3 ≦ b ≦ 7.
0, 60.0 ≦ c ≦ 70.0, ₃ to 20 parts by weight of a boron-containing compound in terms of B ₂ O ₃ and 100 parts by weight of a main component satisfying a + b + c = 100, and an alkali metal-containing compound as an alkali metal 1 to 10 parts by weight of carbonate, Sn,
It contains at least one Zr-containing compound in a total amount of 0.3 to 3.5 parts by weight in terms of oxide.

In the present invention, the weight ratio a of MgO in the composition formula is 25 ≦ a ≦ 35, and the weight ratio b of CaO is 0.
3 ≦ b ≦ 7 is because the weight ratio a of MgO is 25% by weight.
This is because the temperature coefficient τf of the resonance frequency becomes too large positively when the weight ratio b of CaO is less than 7% or when the weight ratio b of CaO exceeds 7% by weight.

On the contrary, when the MgO weight ratio a exceeds 35% by weight or when the CaO weight ratio b is less than 0.3% by weight, the temperature coefficient τf of the resonance frequency becomes too negative. Because. Therefore, MgO weight ratio a and Ca
The weight ratio b of O is 25.0 ≦ a ≦ 35.0, 0.3 ≦ b
≦ 7.0, especially from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic, 28.0 ≦ a ≦ 34.0,
0.4 ≦ b ≦ 6.5 is preferable.

Further, the weight ratio c of TiO ₂ is 60 ≦ c ≦
The reason for setting 70 is that the Q value decreases when the weight ratio c of TiO ₂ is less than 60% by weight or exceeds 70% by weight. Therefore, the weight ratio c of TiO ₂ is 60 ≦ c ≦ 7.
Specified as 0, especially from the viewpoint of the Q value of dielectric porcelain 6
4 ≦ c ≦ 68 is preferable.

The starting materials are MgTiO ₃ and CaTi.
The use of O ₃ further improves the Q value and facilitates control of the temperature coefficient. That is, (100-x) MgT
_{3 to} 20 parts by weight of the boron-containing compound in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component represented by iO ₃ -xCaTiO ₃ (where x represents a weight ratio, 1 ≦ x ≦ 15). Parts, 1 to 10 parts by weight of the alkali metal-containing compound in terms of alkali metal carbonate, and a total of 0.3 to 3.5 parts by weight of at least one of Sn and Zr-containing compounds in terms of oxide.

Here, the weight ratio of CaTiO _{3 in} the main component is set to 1 ≦ x ≦ 15, because the weight ratio of CaTiO ₃ is 1.
When it is less than wt%, the temperature coefficient τf of the resonance frequency is largely deviated to the negative side, and the weight ratio is 15 wt%.
This is because the temperature coefficient τf of the resonance frequency is greatly deviated to the plus side when the value exceeds. Therefore, the weight ratio x of CaTiO ₃ is specified to be 1 to 15% by weight, and particularly 1 to 10 from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic.
Weight percent is preferred.

Further, in the present invention, with respect to the above main component,
The boron-containing compound is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and the alkali metal-containing compound is 1 to 1 in terms of the alkali metal carbonate.
10 parts by weight, at least one of Sn and Zr-containing compounds is added in a total amount of 0.3 to 3.5 parts by weight in terms of oxide, and is added to 100 parts by weight of the main component as described above. the boron-containing compound was added 3 to 20 parts by weight terms _of B ₂ O _3, when the added amount of B ₂ O ₃ is less than 3 parts by weight does not 1100 ° C. But sintering simultaneously with Ag or Cu This is because the firing becomes impossible and, conversely, when the amount exceeds 20 parts by weight, the crystal phase changes and the Q value decreases.

Therefore, the addition amount of the boron-containing compound is specified to be 3 to 20 parts by weight in terms of B ₂ O _{3 with} respect to the main component,
Particularly, from the viewpoint of the Q value of the dielectric porcelain, 3 to 15 parts by weight is desirable. Examples of the boron-containing compound include metallic boron and B ₂
There are O ₃ , colemanite, CaB ₂ O _{4 and the} like.

The alkali metal-containing compound is added in an amount of 1 to 10 parts by weight in terms of the alkali metal carbonate, which is 1100 ° C. when the addition amount of the alkali metal-containing compound, for example, the lithium-containing compound is less than 1 part by weight. But without sintering,
Simultaneous firing with Ag or Cu is not possible, on the contrary, 1
This is because if it exceeds 0 parts by weight, the crystal phase changes and the Q value decreases. Therefore, the addition amount of the alkali metal-containing compound is specified to be 1 to 10 parts by weight in terms of alkali metal carbonate, for example, Li ₂ CO _{3 with} respect to 100 parts by weight of the main component, and particularly in view of the Q value of the dielectric porcelain. From 3 to 7
Parts by weight are desirable.

Examples of the alkali metal include Li, Na and K, and among these, Li is particularly desirable.
Examples of the alkali metal-containing compound include carbonates and oxides of the above alkali metals.

The present invention is characterized in that the boron-containing compound and the alkali metal-containing compound are added and contained at the same time. The reason for this will be explained. When only the boron-containing compound is blended with the above main component, if the blending amount is too small, the firing temperature cannot be lowered sufficiently and the sintering may be performed at a temperature not higher than the melting point temperature of Ag or Cu. Can not.

Although the sintering temperature is lowered when the compounding amount is large, the boron-containing compound is a main component of M at a high temperature such as during firing.
Since reacts with gTiO ₃ -CaTiO ₃ system, if the amount is too large, MgTiO ₃ -cat after firing
The residual amount of iO ₃ decreases, and a high Q value cannot be maintained. Therefore, when only the boron-containing compound is added, it is not possible to obtain a dielectric ceramic composition having excellent low sintering temperature and excellent dielectric properties in a high frequency region.

That is, when only the boron-containing compound is added, if the addition amount is less than 3 parts by weight in terms of B ₂ O ₃ , the sintering temperature does not fall below 1050 ° C. If the amount of B ₂ O ₃ is more than 20 parts by weight, the sintering temperature is 1050.
℃ can be reduced below, MgTiO ₃ -CaTiO ₃ as a boron-containing compounds described above in the firing or the like high temperatures
This is because the Q value decreases because it reacts with.

In the case of this composition, the effect of lowering the sintering temperature of the composition by the addition of the boron-containing compound and the effect of improving the dielectric properties of the porcelain composition after firing are in a trade-off relationship. However, it is difficult to obtain a composition having both a low sintering temperature and excellent dielectric properties such as a high Q value.

On the other hand, when only the alkali metal-containing compound such as Li, Na and K is added to the main component, the sintering temperature of the composition can be almost lowered even if the addition amount is increased. Therefore, a composition that can be sintered at 1050 ° C. or lower cannot be obtained.

On the other hand, in the composition of the present invention in which the boron-containing compound and the alkali metal-containing compound are combined and added at specific ratios, the boron-containing compound and MgTi
Excessive reaction with O ₃ —CaTiO ₃ system and the like can be suppressed, and the sintering temperature can be further reduced as compared with the case where only the boron-containing compound is added, and at the same time, the Q value can be prevented from lowering.

And, in the dielectric ceramic composition of the present invention,
Sn-containing compound and Z based on 100 parts by weight of the main component
At least one of the r-containing compounds is contained in a total amount of 0.3 to 3.5 parts by weight in terms of oxide. Where S
A total of 0.3 to 3.5 parts by weight of at least one of the n and Zr-containing compounds in terms of oxide is contained outside the range, when the addition effect is not so great, or when the Sn and Zr-containing compound is not used. On the contrary, the Q value decreases, and from the viewpoint of the Q value of the dielectric ceramic, 0.5 to
3.0 parts by weight is desirable.

In the present invention, oxides such as Si, Zn and Mn may be added and contained within a range that does not adversely affect the dielectric properties, and in this case, low temperature firing becomes possible.

The dielectric ceramic composition of the present invention is, for example, M
Raw material powders of gCO ₃ , CaCO ₃ , and TiO ₂ were weighed so as to have predetermined amounts, mixed and pulverized, and 1100 to 1
Calcination is performed in the air at a temperature of 300 ° C. for 1 to 3 hours. The obtained calcined product is mixed with, for example, B ₂ O ₃ , Li ₂ CO ₃ and Sn.
Each powder of O ₂ and ZrO ₂ is weighed to a predetermined amount,
After mixed and pulverized and molded into a predetermined shape by a well-known method such as press molding or doctor blade method, 0.5 to 2 at 900 to 1050 ° C. in an oxidizing atmosphere such as air or a non-oxidizing atmosphere such as nitrogen atmosphere. It is obtained by firing for 0.0 hours.

[0031]

【Example】

Example 1 First, MgCO ₃ , CaCO ₃ , and Ti having a purity of 99% or more
Each raw material powder of O ₂ was weighed so that the amounts shown in Tables 1 and 2 were obtained, and pure water was added to the raw material powder as a medium for 24 hours.
After mixing in a ball mill with rO ₂ balls, the mixture is dried and then the dried product is dried in air at 120
It was calcined at a temperature of 0 ° C. for 1 hour.

B ₂ O ₃ powder and Li ₂ C were added to the obtained calcined product.
O ₃ , SnO ₂ , and ZrO ₂ powders were weighed so as to have the ratios shown in Tables 1 and 2, and mixed in the above ball mill for 24 hours, and then 1% by weight of polyvinyl alcohol was added as a binder and then granulated, Approximately 1 ton / cm ^{2 of} the granulated product
12mm in diameter and 10m in height after press molding
A cylindrical molded body of m was produced.

Thereafter, the molded body was heated in the air at a temperature of 400 ° C. for 4 hours to remove the binder, and subsequently fired in the air at each temperature shown in Tables 1 and 60 for 60 minutes. Both end surfaces of the thus obtained cylindrical body were flat-polished to prepare a sample for dielectric property evaluation.

The dielectric characteristics are evaluated by using a dielectric cylinder resonator method using the above-mentioned evaluation sample and setting the resonance frequency to 6 to 8 G.
And the relative permittivity εr of each sample and 1 / tan δ at 7 GHz, that is, the Q value, are measured at -40 Hz.
Temperature coefficient τ of resonance frequency in the temperature range of + 85 ° C
f was measured. The results are shown in Tables 1 and 2.

[0035]

[Table 1]

[0036]

[Table 2]

According to Tables 1 and 2, the dielectric ceramic composition of the present invention can be fired at a relatively low temperature of 900 to 1050 ° C., and has a relative dielectric constant εr of 18 or more, and Sn.
The Q value can be improved as compared with the sample containing neither O ₂ nor ZrO ₂ , and the Q value at 7 GHz satisfies 3000 or more, and the temperature coefficient τf of the resonance frequency is ± 40 ppm /
It can be seen that it has excellent properties within ℃. Sample No.
In 58, Na ₂ CO ₃ was used instead of Li ₂ CO ₃ .

Example 2 First, raw material powders of MgTiO ₃ and CaTiO _{3 having} a purity of 99% or more were weighed so that the amounts shown in Table 3 were obtained, and pure water was added to the raw material powder as a medium for 24 hours. After mixing with a ball mill using _two balls, the mixture was dried, and then the dried product was calcined in the atmosphere at a temperature of 1200 ° C. for 1 hour.

B ₂ O ₃ and Li ₂ C were added to the obtained calcined product.
O ₃ , SnO ₂ , and ZrO ₂ powders were weighed so that the ratios shown in Table 3 were obtained and mixed in the above ball mill for 24 hours, and then 1% by weight of polyvinyl alcohol was used as a binder.
After the addition, granulation was carried out, and the granulated product was press-molded under a pressure of about 1 ton / cm ² to produce a cylindrical molded body having a diameter of about 12 mm and a height of 10 mm.

Thereafter, the molded body was heated in the air at a temperature of 400 ° C. for 4 hours to remove the binder, and subsequently fired at the respective temperatures shown in Table 3 in the air for 60 minutes. Both end surfaces of the thus obtained cylindrical body were flat-polished to prepare a sample for dielectric property evaluation. Evaluation of the dielectric properties was performed in the same manner as above, and the results are shown in Table 3.

[0041]

[Table 3]

According to Table 3, the dielectric ceramic composition of the present invention can be fired at a relatively low temperature of 1050 ° C. or lower, the relative dielectric constant εr is 19 or more, and the Q value does not include SnO ₂ and ZrO _2. It is higher than the sample and the Q value can be 4000 or more, and the temperature coefficient τf of the resonance frequency is ±
It can be seen that it has excellent characteristics within 30.

[0043]

In the dielectric ceramic composition of the present invention, ₃ to 20 parts by weight of a boron-containing compound in terms of B ₂ O ₃ and 100 parts by weight of a main component having a predetermined composition, and an alkali metal-containing compound are added. 1 to 10 parts by weight in terms of alkali metal carbonate,
Since at least one of Sn and Zr-containing compounds was added in an amount of 0.3 to 3.5 parts by weight in terms of oxide, the content was 1050.
℃ can relatively low temperature co-fired with the conductive metal such as Ag and Cu in the following, which has a high dielectric constant at high frequencies, than in the case containing no SnO _2, ZrO ₂ Q
The value can be increased, and electronic components and boards can be made even smaller and have higher performance.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-8-208330 (JP, A) JP-A-6-349334 (JP, A) JP-A-62-216107 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01B 3/12 C04B 35/46

Claims (2)

(57) [Claims] 1. A Mg as the metal element, Ca, a composite oxide containing Ti, when expressed as aMgO · bCaO · cTiO ₂ the formula by weight ratio of the metal element oxides, wherein a, b and c are 25.0 ≦ a ≦ 35.0 0.3 ≦ b ≦ 7.0 60.0 ≦ c ≦ 70.0 a + b + c = 100, and 100 parts by weight of the main component. ,
The boron-containing compound is ₃ to 20 parts by weight in terms of B ₂ O ₃ , and the alkali metal-containing compound is 1 to 1 in terms of alkali metal carbonate.
A dielectric ceramic composition containing 0 part by weight, at least one of Sn-containing compounds and Zr-containing compounds in a total amount of 0.3 to 3.5 parts by weight in terms of oxide. 2. A composite oxide containing Mg, Ca, and Ti as metal elements, the composition formula of which is (100-x) M.
gTiO ₃ —xCaTiO ₃ (where x represents a weight ratio, 1 ≦ x ≦ 15), and the main component 1
Relative to 100 parts by weight, 3 to 20 parts by weight of a boron-containing compound in terms _of B ₂ O _3, 1 to 10 parts by weight of alkali metal-containing compound with an alkali metal carbonate terms of Sn-containing compound and Zr-containing compound of at least A dielectric porcelain composition comprising a total of 0.3 to 3.5 parts by weight in terms of oxide.