JP2002187768A - Low temperature sintering dielectric material for high frequency and sintered body of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric material having a low relative dielectric constant and low dielectric loss which can be calcined at <=1000 deg.C and can be used as high frequency circuit parts, and to provide a dielectric material which shows not much difference in the coefficient of thermal expansion from that of alumina ceramics and which enables use of conventional overcoat glass. SOLUTION: The material consists of, by mass %, 50 to 90% borosilicate glass consisting of 70 to 85% SiO2, 10 to 25% B2O3, 0.5 to 5% K2O and 0.01 to 1% Al2O3 in terms of oxides, and 10 to 50% of one or more kinds of SiO2 fillers selected from the group of α-quartz, α-cistobalite and β-tridymite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric material used for manufacturing wiring boards and circuit parts, which can be sintered at a low temperature of 1000.degree. C. or less, and a sintered body thereof. The present invention relates to a dielectric material having a low relative dielectric constant and a low dielectric loss that can sufficiently cope with a high-frequency circuit used for applications such as communication and wireless LAN, and a sintered body thereof.

[0002]

2. Description of the Related Art Alumina ceramics, which have been widely used as wiring boards and circuit components, have a high relative dielectric constant of 10 and are disadvantageous in that signal processing is slow. In addition, since tungsten, which is a high melting point metal, is used as the conductor material, conductor loss increases. The glass-ceramic dielectric material developed to compensate for the disadvantage is a composite material of glass and alumina filler and has a relative dielectric constant of 6 to 8, which is lower than that of alumina ceramic. In addition, since firing can be performed at a temperature of 1000 ° C. or less, there is an advantage that silver or copper having low conductor loss can be used as the internal conductor.

[0003]

However, in recent years,
As the frequency of signal processing becomes higher, there is an increasing demand to further lower the dielectric constant of dielectric materials.

An object of the present invention is to provide a dielectric material which can be fired at a temperature of 1000 ° C. or less and has a low dielectric constant and a low dielectric loss which can be used as a high-frequency circuit component. Another object of the present invention is to provide a dielectric material which does not have a great difference from the thermal expansion coefficient of alumina ceramics and can use existing overcoat glass.

[0005]

The low-temperature sintered dielectric material for high frequency waves according to the present invention is expressed in terms of mass percentage as Si oxide in terms of oxide.
_{O 2 70~85%, B 2 O} 3 10~25%, K 2 O 0.
50-90% of borosilicate glass composed of 5-5% and 0.01-1% of Al ₂ O ₃ , α-quartz, α-cristobalite,
at least one SiO ₂ selected from the group of β-tridymite
It is characterized by comprising 10 to 50% of a filler.

Further, the sintered body of the present invention has a mass percentage of 70 to 85% of SiO ₂ and B ₂ O _{3 of} 10 to 10% in terms of oxide.
_{25%, K 2 O 0.5~5%} , Al 2 O 3 0.01~
1-% borosilicate glass 50-90% and α-quartz,
It is characterized by being obtained by sintering a raw material powder comprising 10 to 50% of at least one kind of SiO ₂ filler selected from the group consisting of α-cristobalite and β-tridymite.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The low-frequency sintered dielectric material for high frequency waves of the present invention can be co-fired with a silver or copper conductor material at a temperature of 1000 ° C. or less. The sintered body has a relative dielectric constant of 3
-4, has a property of dielectric loss of 0.003 or less.

The dielectric material of the present invention is a glass-ceramic composite material comprising borosilicate glass and SiO ₂ filler.

The reason why the composition of the borosilicate glass is limited as described above will be described below.

[0010] SiO ₂ is a main component of borosilicate glass. Sintering temperature of 1000 ° C when SiO ₂ is more than 85%
That is all. If it is less than 70%, the dielectric constant does not become 4 or less. A preferred range of SiO ₂ is 78 to 83%.

B ₂ O ₃ is a component that lowers the viscosity of glass. If B ₂ O ₃ is more than 25%, the water resistance deteriorates. If less than 10%, the sintering temperature will be 1000 ° C. or higher. A preferred range of B ₂ O ₃ is 16 to 20%.

K ₂ O has the effect of lowering the melting temperature of glass and suppressing the diffusion of silver when silver is selected as the conductor material. If K ₂ O exceeds 5%, high-frequency dielectric loss increases, and the coefficient of thermal expansion also increases. 0.5
%, There is no effect of lowering the melting temperature. Suitable ranges of K ₂ O is 1-3%.

Al ₂ O ₃ is a component that improves the chemical durability of glass and also improves the dielectric strength voltage. A
When l ₂ O ₃ is less than 0.01%, chemical durability is deteriorated, and alkali (K ₂ O) is easily eluted in a wet process at the time of pulverization or sheet molding. In addition, the insulation withstand voltage also decreases, and if the dielectric layer is made thinner with the downsizing of the substrate or the component, short-circuiting easily occurs. If the content of Al ₂ O ₃ is more than 1%, the melting temperature of the glass becomes too high. Al ₂
Suitable range of O ₃ is 0.01 to 0.5%.

The SiO ₂ filler used in the low-temperature sintered dielectric material for high frequency waves according to the present invention comprises α-quartz and α-quartz.
At least one selected from the group consisting of cristobalite and β-tridymite. The reason for selecting these fillers is that the dielectric constant and dielectric loss are low, and as a result, the dielectric constant and dielectric loss of the composite material can be reduced.

In the present invention, the ratio of the glass to the filler is 50 to 90% by weight, preferably 60 to 80% by weight, and the filler is 10 to 50% by weight, preferably 20 to 4% by weight.
0% by mass. The reason for such limitation is that if the filler content is more than 50%, the filler is not densified, and if the filler content is less than 10%, the bending strength becomes too low, and it is difficult to achieve low dielectric loss.

The material of the present invention having the above structure can be used, for example, in the form of a green sheet.

When used as a green sheet, a binder, a plasticizer and a solvent are used together with a dielectric material comprising a mixture of glass ceramic raw material powders prepared to have the above composition.

The content of the dielectric material in the green sheet is generally about 60 to 80% by mass.

The binder is a component that increases the strength of the film after drying and imparts flexibility, and its content is generally about 5 to 30% by mass. As the binder, polyvinyl butyral, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used, and these can be used alone or in combination.

The plasticizer is a component that controls the drying speed and imparts flexibility to the dried film. The content of the plasticizer is generally about 0.1 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate, and the like can be used, and these can be used alone or as a mixture.

As the solvent, for example, toluene, methyl ethyl ketone and the like can be used.

As a general method for producing a green sheet, a slurry composed of a dielectric material powder, a binder, a plasticizer, and a solvent is formed into a sheet on a film such as polyethylene terephthalate (PET) by a doctor blade method. I do. After forming the sheet, the solvent and the solvent are removed by drying to obtain a green sheet.

Next, the sintered body of the present invention will be described.

The sintered body of the present invention is obtained by sintering the dielectric material provided in the form of the above green sheet or the like at a temperature of 900 to 1000 ° C. for 20 to 120 minutes to obtain a dielectric constant and a dielectric constant. It has the characteristic of low dielectric loss.

The sintered body of the present invention is applicable to various uses. For example, in the case of an insulating layer application of a multilayer substrate, the dried green sheet is cut into a predetermined size, and then subjected to mechanical processing to form a through-hole. Print on the green sheet surface. Subsequently, a plurality of green sheets are laminated and integrated by thermocompression bonding. Further, by firing the laminated green sheet, a multilayer substrate having an insulating layer (sintered body) made of glass ceramic can be obtained. It can be used as a constituent material of various electronic components such as a semiconductor package and a laminated chip component in addition to the use of a multilayer substrate.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

[0027]

[Table 1]

[0028]

[Table 2]

First, a glass raw material was prepared so as to have a composition shown in the table, and then put in a platinum crucible at 1500 to 1600 ° C.
For 3 to 6 hours, and formed into a thin plate by a water-cooled roller. Next, the formed body was roughly crushed by a ball mill, and then wet-ground by adding alcohol to obtain a glass powder having an average particle diameter of 0.5 to 3 μm. Further, a ceramic powder (average particle size: 2 μm) shown in the table was added and mixed to obtain a sample.

Next, a slurry was prepared by adding 15% by mass of polyvinyl butyral as a binder, 4% by mass of butylbenzyl phthalate as a plasticizer, and 30% by mass of toluene as a solvent to each sample. Next, the slurry was formed into a green sheet by a doctor blade method, dried, cut into a predetermined size, and then a plurality of sheets were laminated and integrated by thermocompression bonding. Further, a sintered body was obtained by firing the laminated green sheet.

The firing temperature is the firing temperature of a sample fired at the lowest temperature among samples in which ink is applied to a sintered body fired at various temperatures and then wiped off and no ink remains (= densely sintered). did. Further, regarding the obtained sintered body, dielectric constant, dielectric loss, thermal expansion coefficient, alkali (K
It was evaluated ₂ O) elution. The results are shown in each table.

As is clear from the table, the example No. 1 to
Each sample of No. 4 could be fired at a temperature of 1000 ° C. or less. The dielectric constant is 3.4 to 3.0 at a frequency of 2.4 GHz.
9. Dielectric loss was 0.0010 to 0.0029.

On the other hand, in Comparative Example No. Sample No. 5 is K
Due to the large content of ₂ O, the dielectric loss was increased to 0.0035 and the expansion coefficient was increased to 9.0 ppm. No. Sample No. 6 used alumina as a filler, and thus had a large dielectric constant of 5.0. No. Sample No. 7 contained a large amount of alkali elution because it did not contain Al ₂ O ₃ in the glass composition.

The dielectric loss and permittivity were measured by pressing a raw material powder to a size of 7 × 7 × 70 mm and firing it at 900 to 1000 ° C. as a sample. The measurement was performed by a cavity resonator perturbation method at a measurement frequency of 2.4 GHz.

The coefficient of thermal expansion was measured by a thermomechanical analyzer.

The alkali elution amount was determined by dispersing the glass powder in pure water, and autoclaving at 121 ° C. for 60 minutes.
The amount of alkali in water was evaluated by atomic absorption analysis.

[0037]

When the low-temperature sintered dielectric material for high frequency waves of the present invention is used, since the firing temperature is 1000 ° C. or less, it can be fired simultaneously with silver or copper conductor material. Moreover, the relative dielectric constant is 3
-4.Since it is a glass-ceramic sintered body with low relative dielectric constant and low dielectric loss as dielectric loss of 0.003 or less, it fully demonstrates its function as a dielectric material for signal processing in a high frequency band. However, it can be suitably used for multilayer wiring boards and circuit component applications.

Claims (3)

[Claims] 1. The method according to claim 1, wherein the mass percentage is SiO
_Two 70-85%, B _TwoO_Three 10-25%, K_TwoO 0.5
~ 5%, Al_TwoO_Three Borosilicate gas consisting of 0.01-1%
50-90% of lath and α-quartz, α-cristobalite,
at least one SiO selected from the group of β-tridymite_Two
High frequency characterized by comprising 10 to 50% of filler
For low temperature sintered dielectric material. 2. In terms of mass percentage, converted to oxides,
_Two 70-85%, B _TwoO_Three 10-25%, K_TwoO 0.
5-5%, Al_TwoO_Three Borosilicate consisting of 0.01-1%
50-90% glass and α-quartz, α-Cristobaray
And at least one Si selected from the group of β-tridymite
O_TwoSintering raw material powder consisting of 10-50% filler
A sintered body characterized by comprising: 3. The dielectric constant at 1 to 20 GHz is 3 to 4,
Dielectric loss is 0.003 or less, coefficient of thermal expansion is 4-7.5p
3. The sintered body according to claim 2, wherein the sintering temperature is pm / ° C.