JP3215012B2 - Dielectric porcelain composition - Google Patents

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 which can be suitably used in the microwave region and which can be fired at a low temperature, in particular, an inner conductor such as a resonator, a capacitor, a filter or a substrate having the same built therein. The present invention relates to a dielectric ceramic composition suitable for an electronic component having the same.

[0002]

2. Description of the Related Art Conventionally, various dielectric ceramics have been widely used as dielectric materials for electronic components having internal conductors such as resonators, capacitors, filters, or substrates incorporating them, and in recent years, such as mobile phones. With the development and spread of high-frequency devices such as mobile communication, dielectric ceramics have been actively used as electronic components used in a high-frequency region.

When simultaneously firing the dielectric ceramic and the conductor, the conductor is made of alumina, steatite, forsterite or the like so that the printed inner conductor does not melt at the firing temperature of the dielectric ceramic. For example, metals having a melting point higher than the firing temperature of dielectric ceramics such as Pt, Pd, W, and Mo have been used.

However, since the metal has a large conduction resistance, the conventional electronic parts have a problem that the Q value of the resonance circuit is reduced and the transmission loss of the conductor line is increased.

In order to solve such a problem, various dielectric ceramics have been proposed which employ metals such as Ag, Cu and Au having low conduction resistance as conductors 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 components, by increasing the relative dielectric constant εr in a specific frequency region, it is possible to reduce the size of the resonance circuit and inductance. By increasing the Q value of the body ceramic, the Q value of the resonance circuit can be increased and the loss can be reduced, and thus various composite dielectrics have been proposed.

[0006] Conventionally, for example, a dielectric porcelain composition disclosed in Japanese Patent Application Laid-Open No. 4-292460 has disclosed an anorthite composition.
It was made of calcium titanate-based glass and TiO ₂ and could be fired at a low temperature, so that it could be fired simultaneously with a metal such as Ag or Cu as a conductor.

[0007]

However, in the dielectric porcelain 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 region of 4 to 6 GHz, and is low. There has been a limit to miniaturization of electronic components.

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.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can be fired at a relatively low temperature of 900 to 1050 ° C. simultaneously with a conductive metal such as Ag or Cu. High and temperature coefficient of resonance frequency τf
It is an object of the present invention to provide a dielectric porcelain composition having characteristics such as relatively small size and realizing miniaturization and high performance of high-frequency electronic components.

[0010]

The dielectric porcelain composition of the present invention contains Mg, Ca, and Ti as metal elements, and the composition formula based on the weight ratio of these metal oxides is aMgO.bC.
When expressed as aO · cTiO ₂ , a, b, and c are 25 ≦ a
≦ 35, 0.3 ≦ b ≦ 7, 60 ≦ c ≦ 70, a + b + c
= With respect to the main component of 100 parts by weight, represented by 100, 3 to 20 parts by weight of a boron-containing compound in terms _of B ₂ O _3, obtained by adding 1 to 10 parts by weight of a lithium-containing compound with Li ₂ CO ₃ terms Things.

Here, in the above composition formula, the weight ratio a of MgO is 25 ≦ a ≦ 35, and the weight ratio b of CaO is 0.3 ≦ 0.3 ≦
The reason for b ≦ 7 is that the temperature coefficient of the resonance frequency becomes too large when the weight ratio of MgO is less than 25 or when the weight ratio of CaO exceeds 7. Conversely, when the weight ratio a of MgO exceeds 35 or the weight ratio b of CaO is less than 0.3, the temperature coefficient of the resonance frequency becomes too negative. Therefore Mg
The weight ratio a of O and the weight ratio b of CaO are 25 ≦ a ≦ 35,
0.3 ≦ b ≦ 7, and especially 28 ≦ a ≦ 34 from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic.
0.4 ≦ b ≦ 6.5 is preferred.

Further, the weight ratio c of TiO ₂ is set to 60 ≦ c ≦
The reason for setting it to 70 is that when the weight ratio of TiO ₂ is less than 60 or more than 70, the Q value decreases. Therefore, the weight ratio c of TiO ₂ is specified to be 60 ≦ c ≦ 70, and in particular, from the viewpoint of the Q value of the dielectric ceramic, 64 ≦ c ≦
68 is preferred.

In the present invention, the boron-containing compound is added in an amount of ₃ to 20 in terms of B ₂ O _{3 based on} 100 parts by weight of the main component.
Parts by weight of a lithium-containing compound in terms of Li ₂ CO ₃
Although those produced by adding 10 parts by weight, thus with respect to 100 parts by weight of the main component, the boron-containing compound was added 3 to 20 parts by weight terms _of B ₂ O _3, the addition of B ₂ O ₃ When the amount is less than 3 parts by weight, sintering does not occur even at 1100 ° C.
Alternatively, simultaneous sintering with Cu or the like cannot be performed. Conversely, if the amount exceeds 20 parts by weight, the crystal phase changes and the porcelain characteristics deteriorate. Therefore, the addition amount of the boron-containing compound is
It is specified as 3 to 20 parts by weight in terms of B ₂ O _{3 with} respect to 100 parts by weight of the main component, and particularly preferably 5 to 15 parts by weight from the viewpoint of the Q value of the dielectric ceramic. Examples of boron-containing compounds include metallic boron, B ₂ O ₃ , colemanite, CaB ₂ O ₄
Etc.

In addition, the lithium-containing compound is Li ₂ CO ₃
The reason for adding 1 to 10 parts by weight in terms of conversion is that when the added amount of Li ₂ CO ₃ is less than 1 part by weight, sintering is not performed even at 1100 ° C. and simultaneous sintering with Ag or Cu cannot be performed. If the amount exceeds part by weight, the crystal phase changes and the porcelain characteristics deteriorate. Therefore, the addition amount of the lithium-containing compound is specified to be 1 to 10 parts by weight in terms of Li ₂ CO _{3 with} respect to 100 parts by weight of the main component, and especially 3 to 7 parts by weight from the viewpoint of the Q value of the dielectric ceramic. desirable.

The dielectric porcelain composition of the present invention is most suitable for resonators, capacitors, filters or substrates incorporating them, especially for electronic components suitable for high frequency applications, and the internal components formed in these electronic components. Ag, C as the conductor
u, Au, Ni and alloys containing them are used, and Ag and Cu are most desirable in that they have lower conduction resistance.

[0016] The dielectric ceramic composition of the present invention, composition formula _{(100-x) MgTiO 3 -xCaTiO} 3 ( however,
In the formula, x represents a weight ratio, and a boron-containing compound is added to B ₂ O ₃ with respect to 100 parts by weight of a main component represented by 1 ≦ x ≦ 15).
3 to 20 parts by weight of the lithium-containing compound in terms of Li ₂ C
It is obtained by adding 1 to 10 parts by weight in terms of O ₃ .

By using MgTiO ₃ and CaTiO ₃ as starting materials, it becomes possible to contain a large amount of (Mg, Ca) TiO ₃ particles or a large amount of MgTiO ₃ particles and CaTiO ₃ particles as crystals, thereby improving the Q value. The temperature coefficient can be easily controlled. Here, the reason why the weight ratio of CaTiO ₃ is 1 ≦ x ≦ 15 is as follows.
When the weight ratio x of CaTiO ₃ is less than 1, the temperature coefficient τf of the resonance frequency largely shifts to the minus side, and when the weight ratio exceeds 15, the temperature coefficient τf of the resonance frequency increases to the plus side. It is because it shifts. Therefore, C
The weight ratio x of aTiO ₃ is specified to be 1 to 15, and particularly preferably 5 to 10 from the viewpoint of the temperature coefficient τf of the resonance frequency of the dielectric ceramic.

For the same reason as in the above composition, the boron-containing compound is added to
₃ to 20 parts by weight in terms of ₂ O ₃ , lithium-containing compound is L
It is obtained by adding 1 to 10 parts by weight in terms of i ₂ CO ₃ .

In the present invention, oxides such as Si, Zn, Mn, Na, and K may be added and contained as long as they do not adversely affect the dielectric properties. Become.

In the dielectric of the present invention, the boron-containing compound and the lithium-containing compound to be added react with a part of the main constituent elements Mg, Ti and Ca to form a glass phase or a crystal phase, , Ca) at the grain boundaries between the TiO ₃ particles,
Alternatively, (Mg, Ca) TiO ₃ particles, MgTiO ₃ particles, CaTiO ₃ particles, MgO particles, CaO particles, Ti
It will be present at the grain boundary between the O ₂ particles. For boron, the sintered body is converted to an X-ray microanalyzer (EPMA).
It was confirmed that the particles were present at the grain boundaries by observation. Lithium has not yet been identified. However, when lithium 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 lithium exists in the grain boundaries together with boron. In the present invention, it is most preferable that the sintered body contains a large amount of (Mg, Ca) TiO _3.
It is good to contain a lot of ₃ and CaTiO ₃ . From this point, composition formula (100-x) MgTiO ₃ -xCa
For the main component represented by TiO ₃ (1 ≦ x ≦ 15),
A dielectric ceramic composition to which a predetermined amount of a boron-containing compound and a lithium-containing compound are added is most desirable.

The dielectric porcelain composition of the present invention may be, for example, M
Each raw material powder of gCO ₃ , CaCO ₃ , and TiO ₂ is weighed so as to have a predetermined amount, mixed and pulverized.
Calcination is performed at 300 ° C. in the air for 1 to 3 hours. Each powder of B ₂ O ₃ and Li ₂ CO ₃ is weighed to a predetermined amount in the obtained calcined product, mixed and pulverized, molded by press molding or the like, and then subjected to a binder removal treatment in the air. At 900 to 1050 ° C. in air or nitrogen atmosphere.
It is obtained by firing for 5 to 2 hours.

[0022]

According to the dielectric porcelain 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 such as Ag or Cu, has a high relative dielectric constant εr or Q value of the dielectric ceramic, and has a relatively small temperature coefficient τf of the resonance frequency. Electronic components can be reduced in size and improved in performance.

[0023]

【Example】

Example 1 Hereinafter, the dielectric ceramic composition of the present invention will be described in detail based on examples.

First, MgCO ₃ , Ca having a purity of 99% or more
The raw material powders of CO ₃ and TiO ₂ were weighed at the ratios shown in Tables 1 and 2, and pure water was added to the raw material powders as a medium to obtain 2 parts.
After mixing in a ball mill for 4 hours, the mixture was dried,
Next, the dried product was calcined at a temperature of 1200 ° C. for 1 hour.

B ₂ O ₃ powder and Li ₂ C
The O ₃ powder was weighed so as to have the ratios shown in Tables 1 and 2, mixed in a ball mill for 24 hours, added with 1% by weight of polyvinyl alcohol as a binder, and then granulated. By pressing with a pressure of / cm ² , a columnar molded body having a diameter of 12 mm and a height of 10 mm was molded.

[0026]

[Table 1]

[0027]

[Table 2]

Thereafter, the compact was heated at 400 ° C. for 4 hours in the atmosphere to remove the binder, and subsequently calcined in the atmosphere at the temperatures shown in Tables 1 and 2 for 60 minutes. Both end faces of the obtained cylindrical body were polished to prepare a sample for dielectric property evaluation.

The evaluation of the dielectric characteristics was carried out 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, and the relative dielectric constant εr of each sample and 1 / tan δ at 7 GHz, that is, the Q value were measured.
Temperature coefficient τ of resonance frequency in the temperature range of ~ + 85 ° C
f was measured.

According to Tables 1 and 2, the dielectric ceramic composition of the present invention can be fired at a relatively low temperature of 950 to 1050 ° C., and has a relative dielectric constant εr of 18 or more and a Q value of 2000 or more. And the temperature coefficient τf of the resonance frequency is ± 40
It can be seen that it has excellent characteristics within.

Incidentally, 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 were quantitatively analyzed by ICP emission spectroscopy, and Li was quantitatively analyzed by atomic absorption analysis to confirm the composition of the present invention.

Example 2 First, raw material powders of MgTiO ₃ and CaTiO _{3 having} a purity of 99% or more were weighed at the weight ratios shown in Table 3, pure water was added as a medium to the raw material powders, and the mixture was mixed in a ball mill for 24 hours. After drying, the mixture is dried and then the dried product is
Was calcined in the air for 1 hour. B ₂ is added to the obtained calcined material.
O ₃ powder and Li ₂ CO ₃ powder were weighed so as to have the ratios shown in Table 3 and mixed in a ball mill for 24 hours.
After adding 1% by weight of polyvinyl alcohol as a binder, granulation was performed, and the granulated product was press-molded with a pressing force of about 1 t / cm ² to form a columnar molded body having a diameter of 12 mm and a height of 10 mm.

[0033]

[Table 3]

Thereafter, the compact was heated at 400 ° C. in the atmosphere for 4 hours to remove the binder, and then calcined in the atmosphere at each temperature shown in Table 3 for 60 minutes. Both end surfaces of the thus obtained cylindrical body were polished to obtain a dielectric property evaluation sample.

The dielectric characteristics were evaluated by using the above-mentioned sample for evaluation by a dielectric columnar resonator method at a resonance frequency of 6 to 8G.
Hz, and the relative dielectric constant εr of each sample and 1 / tan δ at 7 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 temperature coefficient τf of the resonance frequency is −40 to 20 ° C. based on the resonance frequency at 25 ° C.
f ₁ and a temperature coefficient τf _{2 of} 25 to 80 ° C. were obtained and averaged.

According to Table 3, the dielectric porcelain composition of the present invention can be fired at a relatively low temperature of 1050 ° C. or less, and has a relative dielectric constant εr of 19 or more, a Q value of 3000 or more,
Further, it can be seen that the temperature coefficient τf of the resonance frequency has excellent characteristics within ± 30.

Example 3 In Example 2, the process of No. Using the dielectric powder obtained as No. 3, using an acrylic binder as a cobblestone (zirconia)
Was added to a polypot, and pure water was added, followed by mixing in a ball mill for 24 hours. Next, the mixture was degassed and formed into a green tape having a thickness of 100 μm by a lifting method. Then, a conductor 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
A resonance electrode 2 is formed on one layer, an earth electrode 3 is formed on another layer, and an input / output electrode 4 and an earth 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 (H
As a result of measuring the resonator characteristics and the filter characteristics using P 8719C), the Q value of the resonator was 185 (1.9).
GHz), a filter having a center frequency of 1.9 GHz and an insertion loss of 0.7 dB was obtained.

On the other hand, a system comprising anosite-calcium titanate glass and TiO ₂ disclosed in Japanese Patent Application Laid-Open No. 4-292460 (εr16, Q value 330)
In the material of the above, the Q value of the resonator is 120 (1.9 GHz),
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]

According to the dielectric ceramic composition of the present invention, a boron-containing compound is ₃ to 20 parts by weight in terms of B ₂ O ₃ and a lithium-containing compound is Li to 100 parts by weight of a main component having a predetermined composition. It is 1 to 10 parts by weight in terms of ₂ CO ₃ and can be fired simultaneously with a conductive metal such as Ag or Cu at a relatively low temperature of 1050 ° C. or less, and has a high relative dielectric constant in a high frequency region and a high Q value. In addition, the temperature characteristics of the resonance frequency are excellent, and further downsizing and high performance of the electronic component can be realized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a dielectric resonator using a composition of the present invention.

FIG. 2 is an exploded perspective view of a filter using the dielectric resonator of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 dielectric ceramic 2 resonance electrode 3 earth electrode 4 input / output electrode

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nobuyoshi Fujikawa 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Examiner at Kyocera Research Institute Tatsuo Takeshige (56) References JP-A-7-85726 (JP, A) JP-A-63-151658 (JP, A) JP-A-62-222514 (JP, A) Tokuhoku Sho 60-500496 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] When 1. A containing Mg, Ca, Ti as metal elements, representing the formula by weight of these metal oxides and aMgO · bCaO · cTiO _2, wherein a, b, c is 25 ≦ a ≦ 35 0.3 ≦ b ≦ 760 ≦ c ≦ 70 a + b + c = 100 Based on 100 parts by weight of the main component, 3 to 20 parts by weight of the boron-containing compound in terms of B ₂ O ₃ and lithium-containing compound the dielectric ceramic composition characterized by comprising adding 1 to 10 parts by weight li ₂ CO ₃ terms. 2. A composition of formula (100-x) MgTiO ₃ -x
CaTiO ₃ (where x represents a weight ratio and 1 ≦ x
≦ 15) The boron-containing compound is added in an amount of 3 to 20 parts by weight in terms of B ₂ O ₃ and the lithium-containing compound is added in an amount of 1 to 10 parts by weight in terms of Li ₂ CO _{3 based on} 100 parts by weight of the main component represented by ≦ 15). A dielectric porcelain composition comprising: