JPH05266709A - High frequency dielectric ceramic composition and its manufacture - Google Patents

Abstract

PURPOSE:To provide a high frequency dielectric ceramic composition which has a larger no-load Q value of dielectric ceramic, a smaller temperature coefficient of resonance frequency, the possibility of incorporating a conductor of small resistance and no fear of deformation such as warping in firing, and its manufacture. CONSTITUTION:Mixed powder that TiO2 and RE2Ti2O7, (RE means rare earth metal element) is mixed with glass powder of anorsite calcium titanate group composition is fired, and TiO2 and RE2Ti2O7 are diffused as particles in a basic phase of produced anorsite calcium titanate crystalline. Into the mixed powder, 5-20wt% ZnO-SiO2-B2O3 group glass is added and contained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition, particularly a high frequency dielectric ceramic composition suitable for a wiring board of a high frequency integrated circuit (MIC) and the like, and a method for producing the same.

[0002]

2. Description of the Related Art With the recent development of high frequency devices such as mobile phones, MICs (high frequency integrated circuits) used therein are required to be small and have high performance. The following characteristics are required for the dielectric ceramics used for such an MIC wiring board. That is, first, (1) the relative dielectric constant (εr) is high. This is because when the relative permittivity is high, the resonant circuit and the inductance can be downsized when used at a certain fixed frequency. Also, (2) no-load Q
The value of is high. When the no-load Q value of the porcelain is high, the no-load Q value of the resonance circuit and the inductance using the same can be increased, and the loss can be reduced. Furthermore, (3) the dielectric constant and the temperature coefficient (τ
f) is small. This is to minimize fluctuations in characteristics with respect to temperature changes. Furthermore, (4) the resistance of the conductor is small. This is because when the resistance of the conductor is large, the unloaded Q value of the resonance circuit and the inductance is small, and the transmission loss of the conductor line is large. And (5) simultaneous firing with the conductor is possible, and it is possible to easily manufacture a wiring board having a multilayer structure with a built-in resonance circuit and inductance.
Can be mentioned.

By the way, when simultaneously firing a wiring board made of a dielectric porcelain and a conductor, the conductor is printed with a dielectric so that the conductor printed on the board does not melt at the firing temperature of the dielectric porcelain. It is necessary to select a metal having a melting point higher than the firing temperature of the body porcelain. Therefore, in various conventionally known dielectric porcelain compositions, since the firing temperature is considerably high, P is used as the conductor.
Metals having a high melting point such as t, Pd, W and Mo are used. However, since metals such as Pt, Pd, W and Mo have a large conduction resistance, such a conductor is used. The conventional wiring board has a problem that the unloaded Q value of the resonance circuit and the inductance becomes small and the transmission loss of the conductor line becomes large.

As described above, the Au system, A, which has a small conduction resistance,
It has been considered extremely difficult to employ a g-based or Cu-based metal as a conductor because their melting points are lower than the firing temperature of the dielectric ceramic composition, and it is possible to perform firing at a low temperature. A substrate using a conventional dielectric ceramic composition has a small relative permittivity, and when applied to a MIC wiring substrate, there is an inherent problem that the device cannot be downsized.

For this reason, the applicant of the present invention previously filed Japanese Patent Application No.
-81572, glass powder of anorthite / calcium titanate-based composition, TiO ₂ and RE ₂ Ti ₂ O
₇ (however, RE represents a rare earth metal; the same applies hereinafter) is formed by firing a mixed powder, and the TiO ₂ particles and RE ₂ are mixed in the produced anorthite-calcium titanate crystalline matrix. A dielectric ceramic composition in which Ti ₂ O ₇ particles and dispersed particles are present has been proposed. This dielectric porcelain composition has a melting point (11) for conductors such as Au, Ag, and Cu.
Since it has a characteristic that it can be fired at a temperature lower than (about 00 ° C.), it is possible to advantageously manufacture a multi-layer substrate incorporating these low-resistance conductors.
The addition of TiO ₂ and RE ₂ Ti ₂ O ₇ effectively enhances the relative dielectric constant and the unloaded Q value, and is extremely useful as a composition having excellent dielectric ceramic characteristics. It has features.

However, even in the dielectric porcelain composition previously proposed by the applicant of the present invention having such excellent characteristics, a substrate in which the conductor wiring has a multi-layer structure is formed as in the case of the conventional so-called low temperature firing substrate. In order to obtain, there is an inherent problem that the fired product is deformed such as warped when co-fired with a predetermined conductor material, and there is still room for improvement in this respect.

[0007]

The present invention has been made in view of such circumstances, and its object is to provide a dielectric ceramic with a large unloaded Q value and a temperature coefficient of a resonance frequency. It is an object of the present invention to provide a dielectric ceramic composition for high frequency and a manufacturing method thereof, in which a conductor having a small size and a low conduction resistance can be built in, deformation such as warpage does not occur during firing.

[0008]

The present invention solves the above problems.
In order to achieve, anorthite / calcium titanate-based composition
Glass powder of TiO₂And RE₂Ti₂O₇To
Anod produced by firing mixed powder
In the site-calcium titanate crystalline matrix, the Ti
O₂And RE₂Ti₂O₇Exist as particles dispersed
In the dielectric ceramic composition according to
O-SiO₂-B₂O ₃Based glass of 5 to 20% by weight
High frequency characterized by being added and contained in proportion
A dielectric ceramic composition for waves is the subject of the invention.

Further, according to the present invention, anorthite
TiO2 for glass powder of calcium titanate composition
₂ and RE ₂ Ti ₂ O ₇ were mixed as a raw material, and ZnO—SiO ₂ —B ₂ O ₃ based glass was added to this raw material in a proportion of 5 to 20% by weight, and then, Firing, for precipitating crystals of anorthite and calcium titanate as a main crystal phase, and further dispersing and existing TiO ₂ and RE ₂ Ti ₂ O ₇ as particles in the main crystal phase. A method of manufacturing the dielectric ceramic composition is also the subject of the invention.

[0010]

[Specific Structure / Operation] By the way, the mixed powder which is the main component of the raw material for providing the dielectric ceramic composition in the present invention is composed of TiO ₂ and RE ₂ Ti in comparison with glass powder of anorthite / calcium titanate type composition. It is adjusted by appropriately blending ₂ O ₇ with the required dielectric property, but in order to more advantageously secure excellent dielectric property and low temperature firing property, the following formula should generally be satisfied. It is desirable to mix them in various proportions.

50% by weight ≤ glass powder ≤ 95% by weight 0% by weight ≤ TiO ₂ ≤ 30% by weight 0% by weight ≤ RE ₂ Ti ₂ O ₇ ≤ 40% by weight 5% by weight ≤ TiO ₂ + RE ₂ Ti ₂ O ₇ ≤ Fifty
weight%

In particular, in the proportion satisfying the above equation, Ti
Addition of O ₂ and RE ₂ Ti ₂ O ₇ does not cause problems such as melting of the conductor even when co-firing with low resistance Au-based, Ag-based, Cu-based conductors, etc. Low-temperature firing becomes possible, the conductor line can be advantageously built in, and excellent dielectric ceramic characteristics can be brought out. In addition,
In order to effectively improve the dielectric ceramic characteristics of glass having a calcium titanate composition, TiO ₂ and RE ₂ Ti ₂ O are used.
₇ means that the total amount is 5% by weight or more.

Among such additive components, TiO 2
No. ₂ has a large relative permittivity of about 100, and therefore, by adding it, the relative permittivity of the obtained dielectric ceramic composition can be increased, and the unloaded Q value can also be effectively increased. Of. Further, this TiO ₂ changes the temperature coefficient (τf) of the resonance frequency of the dielectric ceramic composition to the plus side in accordance with the addition amount of TiO _2.
When is on the minus side, τf can be increased by adding TiO ₂ and can be further increased on the plus side.

Since this TiO ₂ powder is usually very fine, it tends to interfere with the sinterability of the glass of anorthite / calcium titanate type composition. Therefore, when TiO ₂ is added in an amount of 15% by weight or more, it is desirable to calcinate in advance to increase the particle size to some extent. For example, by such calcination, B
The particles have an ET specific surface area of about 2 m ² / g or less.

On the other hand, since RE ₂ Ti ₂ O ₇ also has a large relative permittivity of about 40, its addition makes it possible to increase the relative permittivity of the dielectric ceramic composition to be obtained, and also the unloaded Q value. The value can be effectively increased. In addition, RE
RE in ₂ Ti ₂ O ₇ includes Sm, Nd, L
Any of the rare earth metals such as a, Pr, Y, etc. can be used, so that at least one oxide of the rare earth metals or the compound that gives it and TiO ₂ are in a predetermined molar ratio. It is prepared by mixing, calcining and synthesizing, and crushing it. Of course, it is also possible to use plural kinds of rare earth metals at the same time.

By the way, this RE ₂ Ti ₂ O ₇ changes the temperature coefficient (τf) of the resonance frequency of the dielectric ceramic composition to the negative side depending on the addition amount, contrary to the above-mentioned TiO _2. When τf is on the plus side, RE ₂ Ti ₂ O ₇ can be added to reduce τf and further increase it on the minus side. Therefore, the relative dielectric constant and the unloaded Q of the dielectric ceramic composition obtained by appropriately adjusting the addition amount of this RE ₂ Ti ₂ O ₇ and the TiO ₂
While increasing the value, the temperature coefficient can be controlled to a desired value and the value can be reduced (set to zero).

In the present invention, the glass of anorthite / calcium titanate composition, which is the crystalline mother phase of the dielectric porcelain composition, has the main crystals precipitated by firing as anorthite (CaO.Al ₂ O ₃ Basically, there is no problem if the glass composition is a mixed crystal of 2SiO ₂ ) and calcium titanate (CaTiO ₃ ). Above all, it is preferable that Al ₂ O ₃ and SiO, which are the constituents of the crystal, are used.
₂ , CaO, and TiO ₂ are used in proportions of about 20 to 40% by weight, 20 to 40% by weight, 5 to 30% by weight, and ₂ to 20% by weight, respectively.

Furthermore, since the crystallization of the glass powder progresses too fast and the densification becomes insufficient with only the above-mentioned four components, the glass component is preferably used as the glass component.
A BaO component and a B ₂ O ₃ component are further contained.
As the BaO component, BaO itself or BaCO ₃ may be added, but the content as BaO is usually 0 to 2
It is made to be 0% by weight. As the B ₂ O ₃ component, B ₂ O ₃ itself, H ₂ BO ₃ or the like may be added,
Usually, the content as B ₂ O ₃ exceeds 2% by weight, and
And the BaO content of the BaO
And B ₂ O ₃ are contained in a ratio of 5 to 30% by weight. As a result, a dielectric porcelain having a good balance between densification and crystallization can be obtained.

The glass having such a composition can be prepared by various known vitrification techniques.
It can be obtained by melting a mixture obtained by mixing the above-mentioned respective raw material components in a ratio that gives the intended anorthite / calcium titanate composition, quenching the melt, and vitrifying. Usually, the obtained glass is crushed and powdered before use. However, this glass powder is generally used in order to improve its sinterability.
The particle size is adjusted to 0 μm or less, particularly about 1 to 10 μm.

Further, the thus prepared powder mixture of glass powder of anorthite / calcium titanate composition, TiO ₂ and RE ₂ Ti ₂ O ₇ may further contain, if necessary, the dielectric ceramics obtained. It is possible to incorporate certain filler powders in order to improve the mechanical properties of the composition. Examples of such filler powder include alumina, quartz, mullite, forsterite, and quartz glass. Among them, alumina can enhance the strength, and quartz, mullite, and forsterite adjust the thermal expansion coefficient. You can When the amount of such filler powder added is large, it becomes difficult to densify at a low temperature. Therefore, the total amount of these filler powders is usually 30 parts by weight with respect to 100 parts by weight of the dielectric composition. It will be blended so as to have a ratio of not more than about.

Further, in the present invention, an anorthite titanic acid which provides such a dielectric ceramic composition in order to suppress deformation such as warpage during firing of the dielectric ceramic composition configured as described above. Calcium-based glass powder and Ti
ZnO—SiO ₂ —B ₂ O ₃ -based glass is further added to the mixed powder formed by blending O ₂ and RE ₂ Ti ₂ O ₇ .
Although it is added and contained, it will be compounded in a proportion of 5 to 20% by weight in the mixed powder. Capped, the ZnO-SiO ₂ -B ₂ O
_{This is because if} the addition amount of the ₃ type glass is less than 5% by weight, the deformation such as warpage becomes large, and if it is more than 20% by weight, the sinterability is deteriorated.

Incidentally, this ZnO-containing additive is added.
As the SiO ₂ —B ₂ O ₃ based glass, one having a known composition is appropriately selected and used, and for example, it is shown in “Glass Handbook”, page 147, published by Asakura Shoten in 1975,
The following composition will be used.

60% by weight ≤ ZnO ≤ 70% by weight 5% by weight ≤ SiO ₂ ≤ 15% by weight 20% by weight ≤ B ₂ O ₃ ≤ 30% by weight ZnO + SiO ₂ + B ₂ O ₃ = 100% by weight

Further, when the dielectric ceramic composition according to the present invention is manufactured, the above-mentioned glass powder of anorthite / calcium titanate type composition, TiO ₂ and RE ₂ Ti _{2 are used.}
In addition to the mixed powder of O ₇ and Zn,
A raw material powder to which O-SiO ₂ -B ₂ O ₃ based glass was added and contained was used, and from this raw material powder, a molded body formed according to various known molding methods such as a doctor blade method was prepared according to a conventional method. Baking to densify and further crystallize the glass component of anorthite / calcium titanate composition, precipitating crystals of anorthite and calcium titanate as the main crystal phase to form a crystalline matrix phase. In the crystalline crystalline mother phase (main crystalline phase) of such anorthite / calcium titanate composition, Ti
It is intended to obtain a dielectric ceramic composition in which O ₂ and RE ₂ Ti ₂ O ₇ are dispersed and present as particles.

In particular, in the present invention, the firing temperature can be advantageously set to 1100 ° C. or lower in the firing operation, and the lower limit is 8
The temperature may be about 00 ° C. Further, the crystallization of the glass component can be performed at the same time as or subsequent to the firing operation by holding at the firing temperature.
Usually, a temperature of about 850 ° C. to 1100 ° C. is adopted.
Therefore, in the dielectric ceramic composition according to the present invention, when a low resistance conductor such as Au-based, Ag-based or Cu-based conductor is incorporated, firing and crystallization may be performed below the melting point of the conductor. It is possible to satisfactorily avoid the problem that the conductor is melted and the conductor is melted.

[0026]

EXAMPLES Some examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. In addition to the following embodiments, the present invention is not limited to the above specific description, and various changes and modifications are made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It is to be understood that improvements, etc. can be added.

First, aluminum oxide (A
l ₂ O ₃ ), silicon oxide (SiO ₂ ), calcium carbonate (CaCO ₃ ), titanium oxide (TiO ₂ ), barium carbonate (BaCO ₃ ), and boric acid (H ₂ BO ₃ ), Al ₂ O ₃ , SiO ₂ , CaO, TiO ₂ , Ba
The proportions of O and B ₂ O ₃ were weighed so that the glass compositions (A to C) shown in Table 1 below were obtained. Then, put each raw material mixture into a platinum crucible and
After melting at 600 ° C., it was poured into water and rapidly cooled to obtain an anorthite / calcium titanate composition type glass. Then, the various kinds of glass thus obtained were put into an alumina pot together with alumina boulders, pure water was added, and wet pulverization was performed to obtain glass powders I to C.

[0028]

[Table 1]

Separately from the above, ZnO—SiO ₂ —B ₂ O ₃ type glass powders A to C having the compositions shown in Table 2 below.
Prepared.

[0030]

[Table 2]

The thus obtained anorthite / calcium titanate composition type glass powders a to c and ZnO-SiO ₂
Using -B ₂ O ₃ based glass powder A through C, according to the composition shown in Table 3, TiO ₂ and RE ₂ Ti ₂ O
₇ (RE is Nd, La, Sm, or Pr)
Are weighed separately, and further, acrylic binder, plasticizer,
A solvent, a dispersant and the like were added, and the mixture was thoroughly mixed using an alumina pot and alumina cobblestone to form a slurry. And
After adjusting the viscosity of the obtained slurry, the slurry was molded into a green tape having a thickness of 0.4 mm by an ordinary doctor blade method.

[0032]

[Table 3]

On the other hand, a solvent such as Ag powder, a binder and terpineol was used and well kneaded by a triroll mill to prepare a conductor paste for printing.

Then, using the obtained conductor paste, conductor patterns of various patterns were formed on the green tape molded above by the screen printing method. After that, using this printing tape, the green tape and the unprinted green tape were superposed in a predetermined order, and the temperature was 100.
° C., pressure: was allowed integrally laminated under conditions of 100 kgf / cm ^2. Then, by cutting the laminate thus obtained,
A substrate with a built-in stripline resonator was produced by making it 70 mm × 70 mm in size and having a thickness of 2 mm, and then baking it in air at a temperature of 900 ° C. for 1 hour.

Regarding the various fired bodies thus obtained,
The warpage (the difference between the height in a flat state without warpage and the height in a warped state) was measured, and the results are shown in Table 4 below.
It was shown to. Regarding the dielectric constant and the unloaded Q value of the material, pellets were separately prepared and measured by the parallel conductor plate type dielectric resonator method. The results are also shown in Table 4 below. The unloaded Q value was converted to a value at 3 GHz.

[0036]

[Table 4]

As is clear from the results shown in Table 4, the present invention was further applied to a mixed powder obtained by adding TiO ₂ and RE ₂ Ti ₂ O ₇ to glass powder of anorthite / calcium titanate type composition. According to ZnO-SiO
No defects such as cracks were observed in the dielectric porcelain obtained by adding a predetermined amount of _2- B ₂ O ₃ -based glass, and the warpage was extremely high as shown in the table. It was recognized that it was small and had no problem in practical use. On the other hand, No. As shown in Comparative Examples 19 to 28, when the amount of ZnO—SiO ₂ —B ₂ O ₃ based glass added was small, the warpage of the obtained fired body was about 3 mm.
It shows the front and back, it becomes a very deformed one, and Z
the apparatus having the added amount of nO-SiO ₂ -B ₂ O ₃ based glass is large, can not be densified, for which, it was not possible to obtain a dielectric ceramic for the purpose.

[0038]

As is apparent from the above description, the dielectric ceramic composition according to the present invention has a feature that it can be fired at a temperature lower than the melting point of the conductor such as Au-based, Ag-based or Cu-based. In addition to being able to advantageously manufacture a multi-layered substrate incorporating these low-resistance conductors, it is possible to effectively suppress deformation such as warpage of the multi-layered substrate obtained by such firing. It is a thing. In addition, TiO ₂ and RE ₂ T
The addition of i ₂ O ₇ effectively increases the relative permittivity and unloaded Q value of the i ₂ O ₇ , and therefore has the advantage that it can be advantageously used as a composition having excellent dielectric ceramic characteristics. is there.

Claims (2)

[Claims] 1. TiO ₂ and RE ₂ Ti ₂ O ₇ for glass powder of anorthite / calcium titanate composition.
(However, RE represents a rare earth metal) is mixed to form a powder of anorthite / calcium titanate crystalline matrix, and TiO ₂ and RE ₂ T
In a dielectric ceramic composition in which i ₂ O ₇ is dispersed and present as particles, ZnO—SiO ₂ —B is contained in the mixed powder.
_A dielectric ceramic composition for high frequency, wherein ₂ O ₃ glass is added and contained in a proportion of 5 to 20% by weight. 2. TiO ₂ and RE ₂ Ti ₂ O ₇ for glass powder of anorthite / calcium titanate composition.
(However, RE represents a rare earth metal) is used as a raw material, and ZnO—SiO ₂ —B ₂ is added to this raw material.
After adding and containing O ₃ -based glass in a proportion of 5 to 20% by weight, firing is carried out to precipitate crystals of anorthite and calcium titanate as a main crystal phase, and further TiO ₂ and TiO ₂ are contained in the main crystal phase. A process for producing a dielectric ceramic composition for high frequencies, characterized in that RE ₂ Ti ₂ O ₇ is dispersed and present as particles.