JPH04275976A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To offer a dielectric porcelain compsn. exhibiting superior characteristics as dielectric porcelain and ensuring a sintering temp. below the m.p. of an Ag- or Cu-based metal and to produce a circuit board having a multilayered structure and contg. the Ag- or Cu-based metal having low electric resistance as a conductor by simultaneous sintering. CONSTITUTION:Glass powder contg. Al2O3, SiO2, CaO and TiO2 and depositing anorthite and calcium titanate as principal crystals firing is prepd. and 5-30wt.%, in total, of <=20wt.% (expressed in terms of BaO) BaO forming component and <2-20wt.% (expressed in terms of B2O3) B2O3 forming component are added to the glass powder. The resulting glass powder is sintered to obtain a dielectric porcelain compsn.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a dielectric ceramic composition, and particularly to a high frequency dielectric ceramic composition suitable for wiring boards for high frequency integrated circuits (MIC).

0002

BACKGROUND ART With the development of high frequency devices such as mobile phones in recent years, the MICs (high frequency integrated circuits) used in these devices are also required to be small and high performance. The dielectric ceramic used in such a MIC wiring board is required to have the following characteristics. That is, first, (1) the relative dielectric constant (εr) is high. This is because when the dielectric constant is high, it is possible to downsize the resonant circuit and inductance when used at a certain fixed frequency. Also, (2) the Q value is high. If the Q value of the ceramic is high, the Q value of the resonant circuit or inductance using the ceramic can be increased, and the loss can be reduced. Furthermore, (3) the dielectric constant and the temperature coefficient (τf) of the formed resonant circuit are small. This is to minimize variations in characteristics due to temperature changes. And (4) simultaneous firing with a conductor is possible, and a multilayer wiring board with a built-in conductor can be easily produced.

By the way, when simultaneously firing a wiring board made of dielectric porcelain and a conductor, in order to prevent the conductor printed on the board from melting at the firing temperature of the dielectric porcelain, the conductor is coated with a dielectric material. A metal must be selected that has a melting point higher than the firing temperature of the body porcelain. Therefore, since the firing temperature of various conventionally known dielectric ceramic compositions is quite high, Pt, Pt,
Metals with high melting points such as Pb, W, and Mo are used.

For example, when a wiring board is made of alumina, steatite, forsterite, etc., which are known as low-cost dielectric materials, Pt, Pb, and W are usually used as conductors.
, Mo are used. In addition, as a composition having a high dielectric constant, BaO-TiO2 system or a composition in which a part of it is replaced with other elements (Japanese Patent Publication No. 58-209
05), Ba (Mg1/3 Ta2/3) O3
A composition having a composite perovskite structure such as (Japanese Patent Publication No. 59-23048), TiO2 -ZrO2
- Compositions in which SnO2 or a part thereof is replaced with other elements (Japanese Patent Publication No. 35678/1983), BaO-Ti
O2 -RE2 O3 type composition (Japanese Patent Publication No. 56-26
321 Publication, RE: Rare Earth), etc., but these dielectric ceramic compositions also have
Since the firing temperature is quite high, Pt or Pb is used as a conductor.
etc. are used.

However, since metals such as Pt, Pb, W, and Mo have high conduction resistance, in conventional wiring boards using such conductors, the Q value of the resonant circuit and inductance becomes small, and the conductor There was a problem that the transmission loss of the line became large. Thus, conventionally, it has been extremely difficult to use Ag-based, Cu-based, and other metals with low conduction resistance as conductors because their melting points are lower than the firing temperature of dielectric ceramic compositions. It was.

[0006]

[Problem to be solved] Here, the present invention has been made against the background of the above circumstances, and its object is to provide excellent materials such as high dielectric constant, high Q value, and small temperature coefficient. In addition to having dielectric ceramic properties, Ag
The object of the present invention is to provide a dielectric ceramic composition whose firing temperature is lower than the melting point of metals such as Ag-based and Cu-based metals, thereby enabling simultaneous firing with conductors made of Ag-based and Cu-based metals.

[0007] As a result of various studies on many compositions, the present inventors found that BaO and B2 O3 were added as additives to the glass powder in which mixed crystals of anorthite and calcium titanate precipitate during firing. They have discovered that the above objective can be achieved by adding a fixed amount.

[0008]

[Solution] That is, the present invention has been completed based on such knowledge, and is characterized by:
A glass composition containing l2O3, SiO2, CaO, and TiO2, which precipitates anorthite and calcium titanate as main crystals by firing, is further added with a BaO component and a B2O3 component according to the following formula: 0≦χ≦20,2<
A glass powder containing a proportion satisfying y≦20, 5≦χ+y≦30 (where χ and y are the contents as BaO and B2O3, respectively, expressed in weight%), A dielectric ceramic composition formed by firing.

[0009]

[Specific structure/effect] In short, among the above components, Al
2 O3, SiO2, CaO, and TiO2 are
Anorthite (CaO.Al2O3.2SiO2) which constitutes the main crystal of the dielectric ceramic composition according to the present invention
and calcium titanate (CaTiO3). Therefore, the specific content of these components will be determined based on the composition of the crystal, but preferably Al2O3 is 20 to 40% by weight, Si
O2 is 20-40% by weight, CaO is 5-30% by weight,
The proportion of TiO2 is about 2 to 20% by weight. In addition,
In the present invention, these four components may be used in their oxide form as they are, or various compounds that provide these four components upon calcination may be substituted, such as by using CaCO3 as the CaO component. I don't mind anything.

[0010] The excellent feature of such a dielectric ceramic composition is that it has a low melting point (around 1100°C) of metals such as Ag-based and Cu-based metals.
can be fired at lower temperatures. Therefore, even when firing the wiring board and the conductor at the same time, these metals such as Ag and Cu can be used as the conductor, and as a result, it is possible to incorporate a low-resistance conductor into the dielectric ceramic. becomes possible.

However, with only these four components,
When sintering the glass powder, crystallization progresses too quickly, resulting in insufficient densification and poor dielectric ceramic properties. Therefore, in the present invention, in addition to the above glass composition, a BaO component and B2 O3 are added.
The components were contained in predetermined amounts to ensure sufficient densification.

In addition, in the present invention, as the BaO component, BaO itself can be used as it is, or a compound that can generate BaO by firing, such as barium carbonate (BaCO3), can be substituted. , its content as BaO is 0 to 20
% by weight. Also, B2 O3
Besides B2 O3 itself can be used as a component,
Boric acid (H2 B
Although it is also possible to substitute compounds such as BaO3), the content thereof is such that the content as B2O3 is in the range of more than 2% by weight and 20% by weight or less, and those BaO and B2 O3 total amount is 5 to 3
It needs to be contained in such a proportion that it becomes 0% by weight.

That is, in the present invention, the BaO component does not necessarily need to be added, but if its content (content as BaO) exceeds 20% by weight, crystallization proceeds too quickly, resulting in insufficient density. This is because it will not be possible to achieve this goal. Regarding the B2 O3 component, if its content (content as B2 O3) is 2% by weight or less,
Sufficient densification cannot be achieved, and on the other hand, if it exceeds 20% by weight, the fired body (dielectric ceramic composition)
This is because the water resistance of the material decreases, causing problems such as short-circuiting in a humid environment. Furthermore, if the total amount is less than 5% by weight, densification will be insufficient, and if it exceeds 30% by weight, densification will be insufficient and water resistance will deteriorate. It is.

As described above, in the dielectric ceramic composition according to the present invention, the action of the BaO component and the B2 O3 component can effectively suppress crystallization from proceeding too quickly during firing. Both the densification and crystallization of the body porcelain can be achieved in a well-balanced manner, and the properties of the dielectric constant, Q value, and temperature coefficient can be effectively improved.

[0015] As is well known, for example, alumina, quartz, mullite, forsterite, etc. may be appropriately added to such dielectric ceramic compositions as fillers in order to improve their mechanical properties. However, there is no problem. The amount added is usually about 30 parts by weight or less per 100 parts by weight of the dielectric ceramic composition.

[0016]

[Examples] Below, some examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited in any way by the description of such examples. Needless to say, it is not something that can be accepted. In addition to the following examples and the above-mentioned specific description, the present invention includes various changes, modifications, and changes based on the knowledge of those skilled in the art, as long as they do not depart from the spirit of the present invention. It should be understood that improvements and the like may be made.

First, alumina (Al2O
3), quartz (SiO2), calcium carbonate (CaC
O3), titanium oxide (TiO2), barium carbonate (
Al2O3, SiO2, CaO, TiO2 using BaCO3) and boric acid (H2BO3)
, BaO, and B2O3 were weighed so that the glass compositions (Nos. 1 to 13) were shown in Table 1 below. Then, these raw materials were placed in an alumina mortar and thoroughly mixed, the resulting mixture was transferred to a platinum crucible and melted at 1600°C, and then dropped into water and rapidly cooled to produce anorthite/calcium titanate. A composition glass was obtained.

[0018]

[Table 1]

Next, the various types of glasses obtained were put into an alumina pot together with alumina cobbles, pure water was added thereto, wet-pulverized, and then dried. To the anorthite/calcium titanate composition glass powder thus obtained, 1% by weight of PVA was added as a binder and thoroughly mixed, and then granulated by passing through a 40 mesh sieve.

[0020] Using the thus granulated powder, a disk-shaped sample with a size of 20 mmφ x 15 mmt was molded using a press molding machine at a surface pressure of 1 ton/cm2. Thereafter, each molded sample was heated in air at a temperature of 900 to 1000°C for 30 minutes.
After firing for 16 min, each sample was polished to 16 m
The size was adjusted to mφ x 8mmt.

The relative permittivity and unloaded Q of each sample thus obtained were measured by the known parallel conductor plate type dielectric resonator method, and the results are shown in Table 2 below.
It was shown to. Note that the measurement frequency was 8 to 12 GHz. Furthermore, in Table 2, Q is converted to a value at 3 GHz.

[0022]

[Table 2]

As is clear from the results shown in Table 2, the sample containing neither BaO nor B2O3 (No.
1, No. In 2), no densification was achieved and the desired dielectric ceramic could not be obtained. In addition, although the BaO content is sufficient, the B2 O3 content is insufficient.
Sample No. 3 (y=2) and sample No. 3 with sufficient B2 O3 content but too high BaO content. Sample 4 (χ>20) also did not densify. On the other hand, various samples containing BaO and B2O3 as in the present invention can be well densified and form the desired dielectric ceramic, and have a high dielectric constant and a high It exhibited a Q value.

Next, the above No. The mixed powder prepared according to the composition of 8 was put into an alumina pot together with alumina cobbles, and an acrylic organic binder, a plasticizer, toluene, and an alcohol solvent were added thereto and thoroughly mixed to form a slurry. Then, by the doctor blade method,
A green tape with a thickness of 0.1 mm to 1.0 mm was produced. On the other hand, an acrylic organic binder and a terpineol organic solvent were added to the Ag-based powder, and the mixture was thoroughly kneaded using three rollers to obtain a conductive paste for printing. In addition, a commercially available resistor paste for thick film circuits was prepared.

Then, using these pastes, conductor wiring patterns, ground layers, and resistors are printed on the green tape to create, for example, capacitor patterns or stripline or ring types according to the principles of distributed constant circuits. A resonant circuit and inductance are formed. Next, the various green tapes printed with these various conductor patterns were stacked in a predetermined order, and 100
After laminating and integrating the green tape under conditions of 100 kg/cm2 and 100 kg/cm2, through holes were formed in the green tape by punching or the like, and the through holes were further filled with conductive paste to connect each conductor layer. Thereafter, the binder was removed at 500° C., and then the product was fired at 900° C. for 30 minutes.

Note that the surface conductor pattern is formed by simultaneous firing with the substrate, and in addition, a new conductor paste for the surface pattern is applied after baking the substrate, taking into account pattern accuracy, adhesive strength, and solder resistance. It was also formed by a method of printing and firing. In this case, a commercially available Ag/Pt-based or Ag/Pd-based paste for thick film circuits, or a commercially available Cu paste was used as the surface conductor paste.

As a result, melting of the conductor during firing is effectively prevented, and the desired multilayered MIC (high frequency integrated circuit) in which a resonant circuit and a capacitor are built inside the substrate can be obtained. Ta. In addition to the dielectric ceramic substrate itself having excellent dielectric ceramic characteristics, this circuit uses low-resistance metals such as Ag and Cu for the conductor, resulting in low conduction resistance and loss. a small resonant circuit,
Capacitors, inductances, and transmission lines with small transmission losses are advantageously realized, and they have extremely excellent high frequency characteristics.

[0028]

Effects of the Invention As is clear from the above description, the dielectric ceramic composition according to the present invention has a BaO component and a B2 O3 component when mixed crystals of anorthite and calcium titanate are precipitated by firing. Through the action of
This was done to achieve sufficient densification, thereby effectively improving the dielectric ceramic properties. Therefore, it is extremely useful as a wiring board for MIC, etc.

In addition, since such dielectric ceramic compositions can be fired at a relatively low temperature of around 1100°C, they can be fired simultaneously with conductors such as Ag-based and Cu-based conductors. It is possible to fabricate a multilayer wiring board with built-in conductors. Therefore, based on the low conduction resistance characteristics of these Ag-based, Cu-based metals, etc., the transmission loss of the conductor line can be advantageously reduced, and excellent high frequency characteristics can be exhibited.

Claims (2)

[Claims] [Claim 1] Al2O3, SiO2, CaO
, and TiO2, and which causes anorthite and calcium titanate to precipitate as main crystals by firing, and further adds BaO component and B2 O3 component to the following formula:
0≦χ≦20 2<y≦20 5≦χ+y≦30 (However, χ and y are BaO and B2 O3, respectively.
1. A dielectric ceramic composition obtained by firing glass powder containing glass powder in a proportion that satisfies the content (expressed in weight %). 2. The Al2O3, SiO2, C
aO and TiO2 are each 20 to 40% by weight
The dielectric ceramic composition according to claim 1, wherein the dielectric ceramic composition is contained in proportions of 20 to 40% by weight, 5 to 30% by weight, and 2 to 20% by weight.