JPH09235157A - Dielectric porcelain composition - Google Patents

Abstract

(57) Abstract: Since it is fired at the same time as a conductor metal such as Ag or Cu, it can be fired at a low temperature of 900 to 1050 ° C., has a high relative permittivity and a Q value in a high frequency region, and has a resonance frequency temperature. Provided is a dielectric ceramic composition which is excellent in characteristics and can realize further miniaturization and high performance of high-frequency electronic components and circuit boards. A composition formula (1-x) MgTiO ₃ -xCa
TiO ₃ (where x represents a weight ratio, and 0.01 ≦ x
≦ 0.15), based on 100 parts by weight of the main component,
The boron-containing compound is added in an amount of 3 to 30 parts by weight in terms of B ₂ O ₃ , and the potassium-containing compound is added in an amount of 1 to 25 parts by weight in terms of K ₂ CO ₃ .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition applied to electronic circuit boards and electronic parts used in a high frequency region, and is suitable for, for example, resonators, filters, capacitors and LC filters. It is a dielectric ceramic composition used for.

[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.

When simultaneously firing an electronic circuit board or the like made of the dielectric ceramics and a conductor, the conductor is printed on the substrate so that the conductor does not melt at the firing temperature of the dielectric ceramics. It has a melting point higher than the firing temperature of dielectric ceramics such as alumina, steatite, and forsterite, for example, Pt, Pd, W,
Metals such as Mo have been used.

However, since the metal has a large conduction resistance, the conventional electronic circuit board has a problem that the Q value of the resonance circuit and the filter becomes small and the transmission loss of the conductor line becomes large.

In order to solve such a problem, various dielectric ceramics have been proposed which employ a metal such as Ag or Cu having a low conduction resistance as a conductor and can be co-fired at a low temperature. Furthermore, in order to meet the recent demands for miniaturization and high performance of high-frequency electronic circuit boards, it is possible to miniaturize the resonance circuit and the filter by increasing the relative permittivity εr in a specific frequency range, and By increasing the Q value of the body ceramics, the Q values of the resonance circuit and the filter can also be increased, resulting in low loss. Therefore, various composite dielectrics have been proposed.

Conventionally, for example, the dielectric ceramic composition disclosed in Japanese Patent Laid-Open No. 4-292460 comprises anorthite (CaO.Al ₂ O ₃ .2SiO ₂ ) -calcium titanate glass and TiO _2. However, since it can be fired at a low temperature below the melting point of silver, it can be fired simultaneously with a metal such as Ag or Cu as a conductor.

[0007]

However, in the dielectric ceramic composition disclosed in Japanese Patent Laid-Open No. 4-292460, the relative permittivity εr is as low as less than 16 when measured in the high frequency region of 4 to 6 GHz, which is a high frequency electron. There was a limit to the miniaturization of circuit boards.

This dielectric ceramic composition is 6 GHz.
Since the Q value at the measurement frequency was as low as about 330, the Q value of the resonance circuit was low.

Conventionally, as a dielectric ceramic composition having a low loss (high Q value) and a small temperature coefficient of dielectric constant, MgO-CaO-
A porcelain composition having a three-component composition of TiO ₂ is known.
This composition has a dielectric constant of about 20, a Q value at 7 to 8 GHz of about 8000, and a temperature coefficient τf of the relative dielectric constant in the vicinity of 0, and has excellent dielectric properties.

However, this composition has a firing temperature of 1
As high as 300 ° C or higher, Ag as internal conductor (melting point 962
℃) could not be used.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can be fired simultaneously with a conductor metal such as Ag or Cu at a relatively low temperature of 900 to 1050 ° C., and the relative permittivity εr and Q value of the dielectric ceramics can be improved. High and resonant frequency temperature coefficient τf
It is an object of the present invention to provide a dielectric porcelain composition having features such as relatively small size and capable of realizing miniaturization and high performance of a high frequency electronic circuit board.

[0012]

The dielectric ceramic composition of the present invention has a composition formula of (1-x) MgTiO ₃ -xCaTiO ₃ .
₃ (where x represents a weight ratio, and 0.01 ≦ x ≦ 0.
15 to 100 parts by weight of the main component represented by the formula (1), a boron-containing compound is added in an amount of 3 to 30 parts by weight in terms of B ₂ O ₃ , and a potassium-containing compound is added in an amount of 1 to 25 parts by weight in terms of K ₂ CO _3. It will be.

[0013]

The dielectric ceramic composition of the present invention is 900 to 105
Since it can be fired at a relatively low temperature of 0 ° C., it can be fired at the same time as a conductor metal such as Ag or Cu, has a high relative permittivity εr or Q value as a dielectric ceramic, and has a relatively high temperature coefficient τf of the resonance frequency. Because it can be made smaller,
It is possible to realize the miniaturization and high performance of the high frequency electronic circuit board.

It is conceivable to further mix boron or a boron-containing compound in the conventional MgO-CaO-TiO ₂ system to achieve low temperature firing, but only the boron or boron-containing compound is mixed in the MgTiO ₃ -CaTiO ₃ system. In this case, if the compounding amount is small, the firing temperature cannot be lowered sufficiently, and the sintering cannot be performed at a temperature below the melting point temperature of Ag or the like.

Further, if the content of boron or the compound containing boron is large, the firing temperature is lowered, but the content of boron or the compound containing boron reacts with the MgTiO ₃ --CaTiO ₃ system at a high temperature during firing. If the amount is too large, the amount of unreacted MgTiO ₃ —CaTiO ₃ remaining after firing becomes small, and a high Q value of, for example, 500 or more cannot be maintained. Therefore, conventional MgO-CaO
It has been difficult to obtain a dielectric porcelain composition for electronic parts which is excellent in both the low firing temperature and the dielectric properties in the high frequency region with a composition obtained by adding only boron or a boron-containing compound to the —TiO ₂ system.

That is, in the MgTiO ₃ -CaTiO ₃ system, 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. It was difficult to obtain a composition having both a low firing temperature and excellent dielectric properties such as a high Q value.

On the other hand, when only an alkali metal-containing compound such as K is added to MgTiO ₃ --CaTiO ₃ , the sintering temperature of the composition can hardly be lowered even if the amount added is increased. It is not possible to obtain a composition that can be sintered below 950 ° C.

On the other hand, according to the present invention, since the boron-containing compound and the K compound are combined and added in a specific amount ratio, respectively, the boron-containing compound and MgTiO ₃ -CaT are added.
Excessive reaction with iO ₃ is suppressed, and the sintering temperature can be further lowered as compared with the case where only the boron-containing compound is added.

The present invention makes it possible to lower the sintering temperature of the dielectric porcelain composition, which has been heretofore difficult, and to improve the dielectric properties such as Q value and τf, by using the above specific combination composition. It is possible to provide a dielectric ceramic composition which can be simultaneously achieved and can be simultaneously fired with a metal conductor such as Ag or Cu, and which is suitable for high performance and downsized electronic parts.

[0020]

The dielectric ceramic composition of the present invention DETAILED DESCRIPTION OF THE INVENTION, composition formula _{(1-x) MgTiO 3 -xCaTiO} 3 ( however, where x represents the weight ratio, 0.01 ≦ x ≦ 0. 15)
A boron-containing compound is added in an amount of 3 to 30 parts by weight in terms of B ₂ O ₃ and a potassium-containing compound is added in an amount of 1 to 25 parts by weight in terms of K ₂ CO ₃ with respect to 100 parts by weight of the main component represented by Is.

Here, the weight ratio x of CaTiO ₃ is 0.0.
1 ≦ x ≦ 0.15 is because the weight ratio of CaTiO ₃ is x
Is less than 0.01, the temperature coefficient of resonance frequency τf
Is greatly deviated to the negative side, and the weight ratio x is 0.
This is because if it exceeds 15, the temperature coefficient τf of the resonance frequency is largely deviated to the plus side. Therefore, CaTiO ₃
The weight ratio x is specified to be 0.01 to 0.15, and in particular, 0.03 to 0.10. Is preferable from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic.

The dielectric ceramic composition of the present invention comprises a main component 10
Relative to 0 parts by weight, the boron-containing compound in terms _of B ₂ O ₃ 3
30 parts by weight, but in which potassium-containing compound obtained by adding 1 to 25 parts by weight K ₂ CO ₃ terms, thus with respect to 100 parts by weight of the main component, a boron-containing compound B ₂ O
₃ to 30 parts by weight in terms of 3 is added, when the boron-containing compound is less than 3 parts by weight, it does not become densified even if the firing temperature of the dielectric ceramic composition is 1100 ° C. This is because if it exceeds, the crystal phase of MgTiO ₃ —CaTiO ₃ reacts with B and changes, and the porcelain characteristics deteriorate. Therefore, the amount of the boron-containing compound added is 100
It is specified to 3 to 30 parts by weight with respect to parts by weight, and particularly 5 to 15 parts by weight is desirable from the viewpoint of the Q value of the dielectric ceramics. Examples of the boron-containing compound include metallic boron, B ₂ O ₃ , colemanite, and CaB ₂ O ₄ .

Also, when only the boron-containing compound is added to the MgTiO ₃ —CaTiO ₃ type composition, when the addition amount is as small as less than 3% by weight in terms of B ₂ O ₃ , the temperature is 1100 ° C. However, it was not densified, and the addition amount was B
1100 ° C when more than 30% by weight in terms of ₂ O ₃
However, even if not densified or even densified, most of MgTiO ₃ —CaTiO ₃ in the composition reacts with the boron compound, and unreacted MgTiO ₃ —CaTiO ₃ crystals are reduced. Is reduced to 500 or less.

Furthermore, with respect to 100 parts by weight of the main component, the potassium-containing compound was added to 25 parts by weight K ₂ CO ₃ terms are potassium-containing compound with K ₂ CO ₃ in terms of 1
When the amount is less than the weight part, even if the firing temperature is 1100 ° C., densification does not occur, and co-firing with Ag or Cu cannot be performed.
If the amount exceeds 5 parts by weight, MgTiO ₃ —CaTiO ₃
This is because the crystal phase of is changed and the porcelain characteristics are deteriorated. Therefore, the addition amount of the potassium-containing compound is specified to be 1 to 25 parts by weight in terms of K ₂ CO _{3 with} respect to 100 parts by weight of the main component, and particularly 5 to 15 from the viewpoint of the Q value of the dielectric porcelain.
Parts by weight are desirable. As the potassium-containing compound, there are metals K, K ₂ CO ₃ , KCl, KF, and KOH.

Further, in the present invention, oxides such as Si, Zn, Mn and Li may be added within a range that does not adversely affect the dielectric characteristics, and in this case, further low temperature firing becomes possible. Further, a small amount of metal element may be mixed from the crushed balls, but there is no problem in characteristics. In the dielectric ceramic composition of the present invention, in particular, the composition formula is (1-x) MgTi
O ₃ xCaTiO ₃ (where x represents a weight ratio,
0.03 ≦ x ≦ 0.10), based on 100 parts by weight of the main component, a boron-containing compound is added in an amount of 5 to 15 in terms of B ₂ O _3.
5 parts by weight of a potassium-containing compound in terms of K ₂ CO ₃
It is desirable to add 5 parts by weight.

The boron-containing compound in the present invention reacts with a part of the main constituent elements Mg, Ti, Ca to form a glass phase, and at the grain boundaries between (Mg, Ca) TiO ₃ particles, Alternatively, (Mg, Ca) TiO ₃ particles, MgTiO
It exists at the grain boundary between the _three particles and the CaTiO ₃ particles. Regarding the boron, it was confirmed that it was present at the grain boundaries by observing the sintered body with an X-ray microanalyzer (EPMA). Where potassium exists is currently unknown. However, when potassium was not added at all, Mg, Ca, and Ti in the main component were diffused to the B side in the grain boundary to form a glass phase. Has decreased. From this result, it is presumed that potassium exists together with boron at the grain boundary. In the present invention, it is most optimal that the sintered body has a large amount of (Mg, Ca) TiO ₃ phase, and next, it is preferable that a large amount of the MgTiO ₃ phase and the CaTiO ₃ phase exist.

The dielectric ceramic composition of the present invention is, for example, M
Each raw material powder of gTiO ₃ and CaTiO ₃ is weighed so as to have a predetermined amount, mixed and pulverized, and this is 1000 to 1300.
Calcination is performed at a temperature of ℃ for 1 to 3 hours. By this calcination (M
g, Ca) produces TiO ₃ . The obtained calcined product is weighed so that the boron-containing compound powder and the potassium-containing compound powder are in a predetermined amount, mixed and pulverized, and molded by press molding or the like, and then debinding in the atmosphere, and thereafter,
It is obtained by firing at 900 to 1050 ° C. for 0.5 to 2.0 hours in the air or a nitrogen atmosphere.

The dielectric porcelain composition of the present invention is most suitable for electronic parts particularly suitable for high frequency applications, such as a resonator, a capacitor, a filter or a substrate having these built therein. Ag, Cu, Au, Ni and alloys containing these are used as the internal conductor to be formed, and Ag and Cu are desirable from the viewpoint of lower conduction resistance. In particular, when Ag is used as the internal conductor, it is possible to perform simultaneous firing at low temperature, and it is not necessary to use a reducing furnace for preventing electrode oxidation.

[0029]

【Example】

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

B ₂ O ₃ powder and K ₂ CO were added to the obtained calcined product.
₃ powders were weighed so as to have the ratio shown in Table 1 and mixed in a ball mill using zirconia balls 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 t / cm ² to obtain a cylindrical molded body having a diameter of about 12 mm and a height of 10 mm.

[0031]

[Table 1]

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 Table 1 for 60 minutes.

Both end faces 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.
The relative permittivity εr of each sample and 1 / tan δ at 8 GHz, that is, the Q value is 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 Table 1.

According to Table 1, the dielectric ceramic composition of the present invention can be fired at a relatively low temperature of 900 to 1050 ° C., the relative permittivity εr is 18.5 or more, the Q value is 1510 or more, and the resonance is obtained. It can be seen that the temperature coefficient τf of the frequency has excellent characteristics within ± 25.

The obtained sintered body is alkali-melted in sodium carbonate, and this melt is dissolved in a hydrochloric acid solution. Then, Mg, Ca, Ti, and B in the solution are quantitatively analyzed by ICP emission spectroscopic analysis and K by atomic absorption spectrometry.
a and Ti are represented by the composition formula of the present invention, B is converted into B ₂ O ₃ ,
K was converted into K ₂ CO ₃ and confirmed to be within the range of the composition of the present invention.

Example 2 Using the dielectric powder obtained as No. 12 in Table 1 in Example 1, an acrylic binder was put in a polypot together with cobblestone (zirconia), and pure water was added to add 2.
Mixed in a ball mill for 4 hours. Then, after defoaming the mixture, a green tape having a thickness of 100 μm was formed by a lifting method. Then, a conductor pattern was printed on the obtained green tape by using Ag paste for printing. Then, 34 green tapes were laminated and pressure bonded under the conditions of a temperature of 100 ° C. and a pressure of 300 kgf / cm ² so as to sandwich the green tape on which the conductor pattern was printed.

After cutting the laminate into a predetermined size, the laminate is fired in air at a temperature of 900 ° C. for 2 hours to obtain a stripline resonance having a structure shown in exploded perspective views in FIGS. A container and a filter were prepared.

The dielectric ceramic 1 constituting the stripline resonator shown in FIG. 1 has a three-layer structure, and is integrated by simultaneous firing with a conductor. Dielectric porcelain 1
The resonance electrode 2 is formed on one layer of the above, the ground electrode 3 is formed on the other layer, and the input / output electrode 4 and the ground electrode 3 are provided on the surface of the dielectric ceramic 1 and Has been extended to. One end of the resonance electrode 2 is connected to the ground electrode 3 on the side surface. FIG. 2 shows a filter, and reference numerals are the same as those in FIG.

The stripline resonator and the filter thus obtained are analyzed by a network analyzer (HP
As a result of measuring the resonator characteristic and the filter characteristic using the 8719C), the Q value of the resonator is 150 (1.9).
GHz), a center frequency of 1.9 GHz, and an insertion loss of 0.8 dB was obtained.

On the other hand, in a resonator and a filter having the same thickness as that of the present invention, a dielectric ceramic material is used as in the conventional Japanese Unexamined Patent Publication No. 4-2924.
When the system (εr16, Q value 330) composed of anorthite-calcium titanate type glass and TiO ₂ disclosed in JP-A-60 is used, the Q value of the resonator is 120 (1.9).
GHz) and the insertion loss was 1.0 dB. From this result, it is understood that the electronic component using the dielectric ceramic composition of the present invention has a higher Q value of the resonator and a lower insertion loss than the conventional one.

[0042]

In the dielectric ceramic composition of the present invention, composition formula _{(1-x) MgTiO 3 -xCaTiO} 3 ( however, where x represents the weight ratio, 0.01 ≦ x ≦ 0.15) For 100 parts by weight of the main component represented by
₃ to 30 parts by weight in terms of ₂ O ₃ , K containing potassium-containing compound
_Since 1 to 25 parts by weight in terms of ₂ CO _{3 is} added, 900 to
Since it can be fired at a relatively low temperature of 1050 ° C., it can be fired at the same time as a conductor metal such as Ag or Cu, has a high relative permittivity in a high frequency region, and has a high Q value and a resonance frequency temperature. It has excellent characteristics and can realize further miniaturization and higher performance of high-frequency electronic circuit boards.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a dielectric resonator manufactured in an example of the present invention.

FIG. 2 is an exploded perspective view of a filter manufactured in the example of the present invention.

[Explanation of symbols]

 1 ... Dielectric porcelain 2 ... Resonance electrode 3 ... Ground electrode 4 ... Input / output electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Isoyama 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Prefecture Kyocera Stock Company Research Institute (72) Inventor Akira Imoto 1-4 Yamashita-cho, Kokubun-shi, Kagoshima Kyocera Corporation Shikisha Research Institute

Claims (1)

[Claims] 1. A composition formula of (1-x) MgTiO ₃ -xCa
TiO ₃ (where x represents a weight ratio, and 0.01 ≦ x
≦ 0.15), based on 100 parts by weight of the main component,
A dielectric ceramic composition comprising a boron-containing compound in an amount of 3 to 30 parts by weight in terms of B ₂ O ₃ and a potassium-containing compound in an amount of 1 to 25 parts by weight in terms of K ₂ CO ₃ .