JP3406787B2 - Manufacturing method of dielectric porcelain - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] [Technical Field of the Invention The present invention relates to a manufacturing method of firing capable dielectric ceramic at low temperatures, in particular,
Manufacture of microwave and millimeter-wave wiring boards used at high frequencies with copper wiring, dielectric resonators used in microwave and millimeter wave regions, dielectric waveguides, and dielectric porcelain used in dielectric antennas It is about the method . 2. Description of the Related Art In recent years, with the era of advanced information, the speed and frequency of information transmission tend to increase. Mobile media such as mobile phones and personal radios, satellite broadcasting, satellite communications, and new media such as CATV have been working to reduce the size of their devices. As a result, microwave circuit elements such as dielectric resonators have been required. In addition, miniaturization is strongly desired. [0003] The size of such a microwave circuit element is based on the wavelength of the electromagnetic wave used. The wavelength λ of an electromagnetic wave propagating in a dielectric having a relative permittivity εr is λ = λ ₀ / (εr) ^1/2 , where λ ₀ is the propagation wavelength in vacuum. Therefore, the circuit element becomes smaller as the permittivity of the circuit board used increases. [0004] Therefore, in order to satisfy the above-mentioned demand for increasing the dielectric constant, for example, as disclosed in JP-A-6-132621, a resin in which inorganic dielectric particles are dispersed in a resin, As shown in JP 260035,
A glass ceramic circuit substrate and the like made of a composite material of a high dielectric constant filler and glass have been proposed. However, the circuit board disclosed in Japanese Patent Application Laid-Open No. 6-132621 has a firing temperature of about 400 ° C. There is a problem that it is not possible to make a proper wiring. Further, most of the conventional glass ceramic materials have a low dielectric constant lower than a dielectric constant of 10,
In addition, the dielectric loss is as large as 20 × 10 ⁻⁴ or more in the microwave region of 10 GHz, and the dielectric loss and the dielectric loss for miniaturization of high-frequency equipment have not been sufficiently studied. Conventional glass ceramics are
It has the advantage of firing at the same time as gold, silver, copper, etc. because firing at a temperature of 00 ° C. or less is possible.
Since the content is required to be not less than% by weight, the properties of the obtained porcelain greatly depend on the properties of the glass. As a result, there is a problem that the excellent properties of the filler component cannot be exhibited. Accordingly, the present invention can be fired at 800 to 1000 ° C., the dielectric having a high dielectric constant, low dielectric loss, particularly in 30GHz or more high-frequency region
An object of the present invention is to provide a method for manufacturing porcelain . Means for Solving the Problems As a result of intensive studies on the above problems, the present inventor has found that by adding glass containing at least SiO ₂ and B ₂ O ₃ to ZnTiO ₃ , By precipitating a crystal phase mainly composed of an ilmenite type crystal phase containing Zn and Ti, a high relative dielectric constant and a low dielectric loss can be obtained.
An active reaction between glass and a liquid phase mainly composed of Zn generated from nTiO ₃ enables densification at a temperature of 1000 ° C. or less with a small amount of glass, and a multilayer structure using gold, silver, copper, etc. as a wiring conductor. The present inventors have found that fine wiring is possible, and have reached the present invention. That is , the method for manufacturing a dielectric ceramic according to the present invention comprises :
85 to 99.95% by weight of ZnTiO ₃ and at least S
A composition comprising 0.05 to 15% by weight of glass containing iO ₂ and B ₂ O ₃ is molded into a predetermined shape, and then fired at 800 ° C. to 1000 ° C. in a non-oxidizing atmosphere. is there. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a dielectric ceramic according to the present invention is described.
The obtained dielectric porcelain is made of ZnTiO ₃ of 85-9.
9.95% by weight and at least SiO ₂ , B ₂ O ₃ , A
l ₂ O ₃ and alkali metal oxides (Li ₂ O, Na ₂
O, K ₂ O) containing 0.05 to 15% by weight of glass
It is composed of The reason why the composition is limited to the above range is that if the amount of glass is less than 0.05% by weight, in other words, if the amount of ZnTiO ₃ is more than 99.95% by weight, 800-1000. At a temperature of ° C., the porcelain cannot be sufficiently densified, and in the porcelain characteristics produced using this composition, the porcelain is not densified, the dielectric constant decreases,
In addition, the dielectric loss increases, and if the amount of glass is more than 15% by weight, in other words, if the amount of ZnTiO ₃ is less than 85% by weight, the liquid phase flows away at a low temperature of 700 ° C. or less, and the shape of the porcelain is damaged. , And the dielectric constant is lower than 15 in terms of the porcelain characteristics, and at the same time, the dielectric loss tangent in the high frequency range of 30 to 60 GHz is higher than 15 × 10 ⁻⁴ . Desired range of the composition ZnTiO ₃ ninety-three to nine
9.9% by weight, 0.1 to 7% by weight of the glass. This dielectric porcelain has a thickness of 800 to 100.
The porcelain can be densified to a relative density of 95% or more by sintering in a temperature range of 0 ° C., and the porcelain formed thereby mainly has the ilmenite type crystal phase 1 as shown in the schematic diagram of the porcelain structure in FIG. The main crystalline phase, Zn and B
And an amorphous grain boundary phase 2 containing The ilmenite type crystal has a crystal structure belonging to a trigonal lattice represented by FeTiO ₃ , and in the porcelain of the present invention, it is presumed that the Fe is replaced by Zn. As the crystal phase in the porcelain, in addition to the ilmenite type crystal phase, T
Secondary crystal phases such as iO ₂ crystal phase (rutile, anatase) 3 and spinel type crystal phase (for example, Zn ₂ TiO ₄ ) 4 may be precipitated. The amorphous grain boundary phase contains at least Zn, B, and Si, and may further contain added glass components. As described above, according to the present invention, the porcelain is made to have an ilmenite type crystal phase containing at least Zn and Ti as a main crystal phase, so that the relative dielectric constant is 15-3.
In addition to being able to be adjusted between 0, a low dielectric loss can be obtained even in a high frequency region. Further, as a method of manufacturing the above porcelain,
As a starting material, ZnTiO ₃ powder and at least Si
Glass containing O ₂ and B ₂ O ₃ is mixed so as to satisfy the above-mentioned composition. The glass used here is SiO 2
₂ 5-80% by weight, the B ₂ O ₃ comprises respectively a rate of 4 to 50 wt%, 30 wt% for Al ₂ O ₃ other components below, the alkali metal oxides in a proportion of 20 wt% or less A mixture containing these oxide components in a predetermined ratio is melted, cooled, and vitrified. In the composition, the ZnTiO ₃ powder is preferably a fine powder having a size of 2.0 μm or less, particularly 1.0 μm or less in order to enhance dispersibility and obtain a high dielectric constant and a low dielectric loss tangent. After appropriately adding a binder to the mixed powder added and mixed in the above ratio, for example, a mold press,
After being formed into an arbitrary shape by cold isostatic pressing, extrusion molding, doctor blade method, rolling method, etc., at a temperature of 800 ° C. to 1000 ° C., particularly 900 to 1000 ° C. in a non-oxidizing atmosphere such as N ₂ or Ar. By baking for 0.1 to 5 hours, the relative density can be made 95% or more. If the firing temperature at this time is lower than 800 ° C., the porcelain will not be sufficiently densified, and if it exceeds 1000 ° C., the densification is possible, but the copper conductor cannot be used. According to the above method of the present invention, ZnTiO ₃
By combining with the specific glass, ZnTiO ₃
As a result of the reaction between the liquid phase containing Zn generated from the above and the specific glass component, an active liquid phase reaction occurs, resulting in 15% by weight.
Porcelain can be densified with the following amount of glass. Therefore, the amount of the amorphous phase at the grain boundary, which causes an increase in dielectric loss, can be minimized. Therefore, a lower dielectric loss can be obtained in a high frequency region. According to the method for producing a dielectric porcelain of the present invention ,
Since the obtained dielectric porcelain can be fired at 800 to 1000 ° C., it can be used particularly as an insulating substrate of a wiring board for wiring gold, silver, copper and the like. In the case of manufacturing a wiring board using such a dielectric porcelain , for example, according to a known tape forming method, for example, a doctor blade method, a rolling method, or the like, the mixed powder prepared as described above is used as an insulating layer. After forming a green sheet for forming, the surface of the green sheet is formed on a surface of the sheet using a conductive paste containing at least one metal of gold, silver and copper, particularly copper powder, for a wiring circuit layer. Then, the wiring pattern is printed in a circuit pattern by a screen printing method, a gravure printing method, or the like, and in some cases, the sheet is filled with the conductor paste after forming through holes or via holes. After that, a plurality of green sheets are laminated and pressed, and then fired under the above conditions, whereby the wiring layer and the insulating layer can be fired simultaneously. EXAMPLES Glass having the composition shown in Table 1 and ZnTiO ₃ having an average particle diameter of 1 μm or less were mixed according to the compositions shown in Tables 2 and 3. [Table 1] Then, an organic binder, a plasticizer, and toluene were added to the mixture, and a green sheet having a thickness of 300 μm was prepared by a doctor blade method. Then, five green sheets are laminated, and 100
Thermocompression bonding was performed by applying a pressure of kg / cm ² . After debinding the obtained laminate in a steam-containing / nitrogen atmosphere at 700 ° C., it was fired in dry nitrogen under the conditions shown in Tables 2 and 3 to obtain a sintered body of the ceramic composition for a multilayer substrate. The dielectric constant and dielectric loss tangent of the obtained sintered body were evaluated by the following methods. The measurement is 1-30 mm in diameter,
A sample having a shape having a thickness of 2 to 15 mm was cut out, and 1.0 to 7
The measurement was performed at 0 GHz by a dielectric cylinder resonator method using a network analyzer and a synthesized sweeper. In the measurement, the dielectric resonator was excited by an NRD guide (non-radiative dielectric line), and the dielectric constant and the dielectric loss tangent were calculated from the resonance characteristics of the TE021 and TE031 modes. The results of the measurement are shown in Tables 2 and 3. Further, the crystal phase to be detected was identified by X-ray diffraction measurement, and the results are shown in Tables 2 and 3. An X-ray diffraction chart of Sample No. 7 is shown in FIG. In addition, as a comparative example, a sintered body was similarly prepared using CaTiO ₃ and SrTiO ₃ instead of ZnTiO ₃ and evaluated (samples Nos. 33 to 36). [Table 2] [Table 3] As is clear from the results shown in Tables 2 and 3, the present invention, in which the ilmenite type crystal phase (ZnTiO ₃ ) crystal phase was precipitated as the crystal phase, had a dielectric constant of 15 to 30,
The dielectric loss tangent at 1 to 70 GHz showed an excellent value of 15 × 10 ⁻⁴ or less. On the other hand, the glass content is 0.05% by weight.
Less sample no. In 11 and 19, the firing temperature was 13
Unless the temperature was raised to 00 ° C., it could not be densified.
On the other hand, Sample No. having a glass content exceeding 15% by weight was used. 1, 1
Sample No. 2 has a low firing temperature due to a large amount of liquid phase, but has a dielectric constant of 1
5, 14 and the dielectric loss is 100 × at 60 GHz.
It exceeded 10-4. In addition, the sample No. using the glasses C and D containing no B2O3. In 20-24,
In any case, densification could not be achieved unless the temperature was raised to 1200 ° C., which did not satisfy the object of the present invention. As comparative examples, CaTiO ₃ , Sr
In Samples Nos. 33 to 36 using TiO ₃ ,
High measurement was not possible at 0 GHz. Example 2 Using the composition of No. 7 in the above example, the diameter was 1 to 30 m.
m, a cylindrical sample having a thickness of 2 to 15 mm was prepared (in the figure). For comparison, general-purpose alumina-based glass ceramics (75% by weight of aluminoborosilicate glass, 25% by weight of alumina) (in the figure), general-purpose low-purity alumina (95% by weight of Al ₂ O ₃ , CaO, MgO, SiO ₂₎ 5
(% By weight) (in the figure) to prepare a sample in the same manner. The prepared samples were prepared at 1 GHz, 10 GHz, and 20 GHz.
The dielectric constant and the dielectric loss tangent were measured by the dielectric cylinder resonator method in high frequency ranges of GHz, 30 GHz and 60 GHz. The results are shown in FIGS. The general-purpose alumina-based glass ceramics had a considerably low dielectric constant of 5, and the general-purpose low-purity alumina had a dielectric constant of 9. On the other hand, the product of the present invention had a high dielectric constant of 28. Alumina-based glass ceramics for general use have a low dielectric loss tangent of 10.times.10.sup.- ⁴ in the low-frequency region, but their characteristics deteriorate as the frequency becomes higher.
If it is higher than GHz, it will be higher than 20 × 10 ^-4 . In addition, general-purpose low-purity alumina is 40 × 10 at 60 GHz.
^-4 and high. On the other hand, the product of the present invention had an excellent dielectric loss tangent of 15 × 10 ⁻⁴ or less even in a high frequency region. As described in detail above, the dielectric porcelain of the present invention
According to the manufacturing method of (1), the dielectric porcelain is 800 to 1000 ° C.
Can be fired simultaneously with wiring of gold, silver, copper, etc. In addition, the porcelain obtained by firing the composition exhibits a high dielectric constant and a low dielectric loss tangent even in a high frequency band of 30 GHz or more, so that it is possible to reduce the size of a microwave circuit element or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of the structure of the porcelain composition of the present invention. FIG. 2 is an X-ray diffraction chart of a porcelain (sample No. 7) of the present invention. FIG. 3 is a diagram showing a relationship between a dielectric constant of a product of the present invention and a conventional product and a measurement frequency. FIG. 4 is a diagram showing a relationship between a dielectric loss and a measurement frequency of a product of the present invention and a conventional product. [Description of Signs] 1 Ilmenite type crystal phase 2 Glass phase 3 TiO ₂ phase 4 Zn ₂ TiO ₄ phase

Claims (1)

(57) [Claim 1] 85-99.95% by weight of ZnTiO ₃ ,
Glass containing at least SiO ₂ and B ₂ O ₃ 0.05 to
A method for producing a dielectric ceramic, comprising: forming a composition comprising 15% by weight into a predetermined shape;