JP3377903B2 - Dielectric porcelain composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a dielectric ceramic composition applied to an electronic circuit board or an electronic component used in a high-frequency range. , Filter, capacitor, LC filter and the like. Conventionally, various dielectric ceramics have been widely used as a dielectric material for electronic circuit boards, electronic components, and the like. In recent years, the development of high-frequency equipment such as mobile communication represented by a cellular phone has been developed. With the spread, dielectric ceramics have been actively used as electronic circuit boards and electronic components used in a high frequency range. [0003] When simultaneously sintering an electronic circuit board or the like made of the dielectric ceramic and the conductor, the conductor is printed on the substrate so that the conductor is not melted at the firing temperature of the dielectric ceramic. 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 small conduction resistance as a conductor and can be co-fired at a low temperature. Furthermore, in order to respond to recent demands for miniaturization and high performance of high-frequency electronic circuit boards, it is possible to reduce the size of resonance circuits and filters by increasing the relative dielectric constant εr in a specific frequency range. By increasing the Q value of the body ceramic, the Q value of the resonance circuit and the filter can be increased and the loss can be reduced. Therefore, various composite dielectrics have been proposed. Conventionally, for example, a dielectric porcelain composition disclosed in Japanese Unexamined Patent Publication (Kokai) No. 4-292460 comprises an anorthite (CaO.Al ₂ O ₃ .2SiO ₂ ) -calcium titanate glass and TiO _2. 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. However, in the dielectric ceramic composition disclosed in Japanese Patent Application Laid-Open No. 4-292460, the relative dielectric constant .epsilon.r is as low as less than 16 in a high frequency range of 4 to 6 GHz. However, there has been a limit to miniaturization of high-frequency electronic circuit boards. This dielectric ceramic composition has a frequency of 6 GHz.
Since the Q value was as low as about 330 at the measurement frequency, 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 a 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 relative dielectric constant of about 0, and has excellent dielectric properties. However, this composition has a firing temperature of 1
High as 300 ° C. or higher, Ag (melting point 962)
° C) etc. could not be used. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can be fired simultaneously with a conductive metal such as Ag or Cu at a relatively low temperature of 900 to 1050.degree. High Q value and temperature coefficient τf of resonance frequency
It is an object of the present invention to provide a dielectric ceramic composition having characteristics such as relatively small size and realizing miniaturization and high performance of a high-frequency electronic circuit board. [0012] [Means for Solving the Problems] The dielectric ceramic composition of the present invention, composition formula (1-x) MgTiO ₃ -xCaTiO
₃ (where x represents a weight ratio, and 0.01 ≦ x ≦ 0.
Relative to 100 parts by weight of the main component represented by 15), the boron-containing compound terms _of B ₂ O ₃ by 3 to 30 parts by weight, the potassium-containing compound and 1 to 25 parts by weight additives contained in K ₂ CO ₃ in terms of It becomes. The dielectric porcelain composition of the present invention has a composition of 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 conductive metal such as Ag or Cu, has a high relative dielectric constant εr or Q value as a dielectric ceramic, and has a relatively high temperature coefficient τf of resonance frequency. Because it can be smaller,
The miniaturization and high performance of the high-frequency electronic circuit board can be realized. It is conceivable to mix boron or a boron-containing compound with the conventional MgO-CaO-TiO ₂ system to achieve low-temperature firing. However, it is also possible to mix only a boron or boron-containing compound with the MgTiO ₃ -CaTiO ₃ system. In this case, if the amount is small, the firing temperature cannot be sufficiently lowered, and sintering cannot be performed at a temperature lower than the melting point temperature of Ag or the like. Further, when the amount of boron or boron-containing compound is large, the sintering temperature decreases, but the amount of boron or boron-containing compound reacts with the MgTiO ₃ —CaTiO ₃ system at a high temperature such as during sintering. Is too large, the unreacted amount of unreacted MgTiO ₃ —CaTiO ₃ after firing decreases, and a high Q value of, for example, 500 or more cannot be maintained. Therefore, the conventional MgO-CaO
With a composition in which only boron or a boron-containing compound is further added to a TiO ₂ -based composition, it has been difficult to obtain a dielectric ceramic composition for electronic components having excellent low-temperature and high-frequency dielectric characteristics. That is, in the MgTiO ₃ —CaTiO ₃ system, the effect of lowering the sintering temperature of the composition due to the addition of the boron-containing compound and the effect of improving the dielectric properties of the porcelain composition after sintering are in a trade-off relationship. With the composition (1), 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 added amount is increased. A composition that can be sintered at 950 ° C. or lower cannot be obtained. On the other hand, according to the present invention, the boron-containing compound and the K compound are combined and added at specific ratios, respectively, so that the boron-containing compound and the MgTiO ₃ —CaT
Excessive reaction with iO ₃ is suppressed, and the sintering temperature can be further reduced as compared with the case where only a boron-containing compound is added. The present invention is intended to reduce the sintering temperature of the dielectric ceramic composition and improve the dielectric properties such as the Q value and τf, which have been difficult in the past, by the above specific combination composition. It is possible to provide a dielectric porcelain composition which can be simultaneously achieved and can be simultaneously fired with a metal conductor such as Ag and Cu, and which is suitably used for high-performance and miniaturized electronic components and the like. 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)
Wherein 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 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 It is. Here, the weight ratio x of CaTiO ₃ is set to 0.0
The condition of 1 ≦ x ≦ 0.15 is the weight ratio x of CaTiO _3.
Is less than 0.01, the temperature coefficient τf of the resonance frequency
Greatly shifts to the minus side, and the weight ratio x is 0.1.
This is because if it exceeds 15, the temperature coefficient τf of the resonance frequency greatly shifts to the plus side. Therefore, CaTiO ₃
Is specified to be 0.01 to 0.15, and particularly preferably 0.03 to 0.10 from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic. The dielectric porcelain composition of the present invention contains 10 main components.
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
_The addition of 3 to 30 parts by weight in terms of 3 means that when the boron-containing compound is less than 3 parts by weight, the dielectric ceramic composition does not densify even at a firing temperature of 1100 ° C. If it exceeds, the crystal phase of MgTiO ₃ —CaTiO ₃ reacts with B and changes, deteriorating the porcelain characteristics. Therefore, the amount of the boron-containing compound added is 100
The amount is specified to be 3 to 30 parts by weight with respect to the weight part, and particularly preferably 5 to 15 parts by weight from the viewpoint of the Q value of the dielectric porcelain. 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 composition, as in the above case, if the addition amount is less than 3% by weight in terms of B ₂ O ₃ , 1100 ° C. However, it does not densify and the addition amount is B
1100 ° C when more than 30% by weight in terms of ₂ O ₃
However, even if it is not densified, or if it is densified, most of the MgTiO ₃ —CaTiO ₃ in the composition reacts with the boron compound, and the number of unreacted MgTiO ₃ —CaTiO ₃ crystals decreases, and as a result, the Q value Is reduced to 500 or less. Furthermore, the reason why the 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 is that the potassium-containing compound is added in 1 part in terms of K ₂ CO _3.
If the amount is less than 1 part by weight, densification does not occur even at a sintering temperature of 1100 ° C., and simultaneous sintering with Ag or Cu cannot be performed.
If it exceeds 5 parts by weight, MgTiO ₃ —CaTiO ₃
Is changed, and the porcelain characteristics deteriorate. Therefore, the amount of the potassium-containing compound to be added 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.
Parts by weight are desirable. Potassium-containing compounds include metals K, K ₂ CO ₃ , KCl, KF, and KOH. 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 properties. In this case, firing at a lower temperature is possible. Further, a small amount of metal element may be mixed from the crushed ball, but there is no problem in characteristics. In the dielectric ceramic composition of the present invention, particularly, the composition formula is (1-x) MgTi.
O ₃ xCaTiO ₃ (where x represents a weight ratio,
0.03 ≦ x ≦ 0.10) and the boron-containing compound in an amount of 5 to 15 in terms of B ₂ O ₃ with respect to 100 parts by weight of the main component represented by the formula:
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 according to the present invention reacts with a part of the main constituent elements Mg, Ti, and Ca to form a glass phase, and at the grain boundaries between the (Mg, Ca) TiO ₃ particles, Alternatively, (Mg, Ca) TiO ₃ particles, MgTiO
₃ particles and CaTiO ₃ particles are present at the grain boundaries. Observation of the sintered body with an X-ray microanalyzer (EPMA) confirmed that boron was present at the grain boundaries. It is currently unknown where potassium is present. However, when potassium was not added at all, Mg, Ca, and Ti in the main component 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 at the grain boundary together with boron. In the present invention, it is most optimal that the sintered body contains a large amount of (Mg, Ca) TiO ₃ phase, and then it is good that the MgTiO ₃ phase and the CaTiO ₃ phase are large. The dielectric porcelain composition of the present invention may be, for example,
Each raw material powder of gTiO ₃ and CaTiO ₃ is weighed so as to have a predetermined amount, mixed and pulverized.
Calcinate at a temperature of ° C. for 1 to 3 hours. By this calcination (M
g, Ca) TiO ₃ is produced. Boron-containing compound powder and potassium-containing compound powder are weighed to a predetermined amount in the obtained calcined material, mixed and pulverized, molded by press molding or the like, and then subjected to a binder removal treatment in the air.
It is obtained by firing at 900 to 1050 ° C. for 0.5 to 2.0 hours in the air or nitrogen atmosphere. The dielectric porcelain composition of the present invention is most suitable for resonators, capacitors, filters or substrates incorporating these, especially electronic parts suitable for high-frequency applications. As the internal conductor to be formed, Ag, Cu, Au, Ni and an alloy containing them are used, and Ag and Cu are desirable from the viewpoint that the conduction resistance is lower. In particular, when Ag is used as the internal conductor, simultaneous firing at a low temperature is possible, and there is no need to use a reduction furnace for preventing electrode oxidation. EXAMPLE 1 First, raw material powders of MgTiO ₃ and CaTiO _{3 having} a purity of 99% or more were weighed so as to have a weight ratio shown in Table 1, and water was added to the raw material powder as a medium. After mixing in a ball mill for 24 hours, 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 ₃ were added to the obtained calcined product.
_{3 The} powders were weighed so as to have the ratios shown in Table 1, 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, the mixture was granulated, and the granulated product was press-molded with a pressure of about 1 t / cm ² to obtain a cylindrical compact having a diameter of about 12 mm and a height of 10 mm. [Table 1] Thereafter, the compact 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 ends of the thus obtained cylindrical body were polished flat to prepare a sample for dielectric property evaluation. The evaluation of the dielectric characteristics is performed by using the above-mentioned sample for evaluation and setting the resonance frequency to 6 to 8 G by the dielectric cylinder resonator method.
Hz, the relative dielectric constant εr of each sample and 1 / tan δ at 8 GHz, that is, the Q value, were measured.
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., has a relative dielectric constant εr of 18.5 or more, a Q value of 1510 or more, and has a resonance. It can be seen that the temperature coefficient of frequency τf has excellent characteristics within ± 25. The obtained sintered body is alkali-melted in sodium carbonate, and the melt is dissolved in a hydrochloric acid solution. Then, Mg, Ca, Ti, and B in the solution were quantitatively analyzed by ICP emission spectrometry, and K was quantitatively analyzed by atomic absorption spectrometry.
a and Ti are represented by the composition formula of the present invention, and B is converted into B ₂ O ₃ ;
K was converted to K ₂ CO ₃ , and it was confirmed that K was 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 into a polypot together with a cobblestone (zirconia), and pure water was added to add 2 to the polypot.
The mixture was mixed in a ball mill for 4 hours. Then, after defoaming the mixture, the mixture was formed into a green tape having a thickness of 100 μm by a lifting method. Then, a conductive pattern was printed on the obtained green tape using a printing Ag paste. Next, 34 green tapes were laminated and pressed at 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. Then, the laminate is cut into a predetermined size, and then baked at 900 ° C. for 2 hours in the air to obtain a strip line type resonance structure shown in an exploded perspective view in FIGS. A vessel and a filter were prepared. The dielectric ceramics 1 constituting the strip line type 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, 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. 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 the symbols are the same as those in FIG. The stripline type resonator and the filter thus obtained were analyzed with a network analyzer (HP
As a result of measuring the resonator characteristics and the filter characteristics using 8719C), the Q value of the resonator was 150 (1.9).
GHz), a filter having a center frequency of 1.9 GHz and an insertion loss of 0.8 dB was obtained. On the other hand, using a resonator and a filter having the same thickness as in the present invention, a dielectric ceramic material is replaced by a conventional Japanese Patent Application Laid-Open No. H4-2924.
In the case of using a system (εr16, Q value 330) composed of an anorthite-calcium titanate glass and TiO ₂ disclosed in Japanese Unexamined Patent Publication No. 60-120, the Q value of the resonator is 120 (1.9).
GHz) and the insertion loss was 1.0 dB. From these results, it can be seen that in the electronic component using the dielectric ceramic composition of the present invention, the Q value of the resonator is higher and the insertion loss is lower than before. [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) to 100 parts by weight of the main component represented by
3-30 parts by weight in terms of ₂ O ₃ , potassium-containing compound is K
_Since 1 to 25 parts by weight in terms of ₂ CO ₃ was added, 900 to
Since it can be fired at a relatively low temperature of 1050 ° C., it can be fired simultaneously with a conductive metal such as Ag or Cu, has a high relative dielectric constant in a high frequency region, has a high Q value, and has a temperature of a resonance frequency. It is also excellent in characteristics, so that further miniaturization and higher performance of the high-frequency electronic circuit board can be realized.

BRIEF DESCRIPTION OF THE 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 an example of the present invention. [Description of Signs] 1 ... Dielectric porcelain 2 ... Resonant electrode 3 ... Earth electrode 4 ... Input / output electrode

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Imoto 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Inside Kyocera Research Institute (56) References JP-A-8-268753 (JP, A) JP-A-8 -208330 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/42-35/50 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claim 1] The composition formula is (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
3 to 30 parts by weight of a boron-containing compound in terms _of B ₂ O _3, a potassium-containing compound a dielectric ceramic composition characterized by being 1 to 25 parts by weight additives contained in K ₂ CO ₃ terms.