JP3420437B2 - Low temperature firing 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 low temperature fired porcelain composition, particularly copper (Cu), silver (Ag), gold (A) having a large relative dielectric constant, a small dielectric loss tangent, and a small conductor resistance.
The present invention relates to a low-temperature fired porcelain composition suitable for a multilayer wiring board with a built-in capacitor, a multilayer wiring board with a built-in filter, etc., which is used in a high frequency region in which a wiring conductor can be formed by cofiring u) and the like.

[0002]

2. Description of the Related Art In the era of advanced information technology in recent years, information transmission has become faster and higher in frequency, and semiconductor elements to be mounted have also become faster and highly integrated, requiring higher density mounting. Therefore, it is widely adopted to incorporate a capacitor or a filter in the wiring board.

Generally, in order to embed a capacitor in a wiring board, a high dielectric constant dielectric material is embedded in a low dielectric constant dielectric material substrate, and electrodes are provided at both ends of the high dielectric constant dielectric material to form a capacitor part. Or by printing electrodes on both ends of a high-dielectric-constant dielectric sheet, sandwiching the high-dielectric-constant dielectric sheet with a low-dielectric-constant dielectric sheet, and stacking to form a capacitor section by simultaneous firing. And so on.

However, in the above method, the dielectrics having different dielectric constants are fired and integrated, so that they easily react with each other,
There is a problem that desired relative permittivity and Q value cannot be obtained.

If it is attempted to form all of the above-mentioned dielectric material with a ferroelectric material having a high dielectric constant, the firing temperature is 1300 to 160.
Only high-melting-point metals such as tungsten (W) and molybdenum (Mo), which have a high conductor resistance, can be used as wiring conductors that can be simultaneously fired at temperatures as high as 0 ° C. Therefore, signals due to conductor loss of the transmission line in the substrate can be applied. However, there is a problem in that it is unsuitable as a material for a wiring board for high frequencies these days.

On the other hand, in order to incorporate a filter in a wiring board, an inductance L, a capacitance C and a resistance R are provided by a wiring conductor and a dielectric, and they are formed by combining them.

The capacitance C can be formed in a smaller space as the dielectric constant of the dielectric is larger. Therefore, the built-in filter can be downsized as the dielectric having a higher dielectric constant is used.

However, if the adjacent wirings are too close to each other, noise is generated due to mutual interference of signals, so that there is a limit to increasing the dielectric constant, and moreover, only the capacitor forming portion is formed of a high dielectric constant dielectric. In that case, as in the case of the capacitor, the signal transmission loss due to the conductor loss of the transmission line becomes a problem.

Therefore, first, in order to reduce the conductor loss of the transmission line in the substrate, Cu, Ag, A having a low conductor resistance is used.
It has been proposed to use glass ceramics obtained by firing a mixture of glass and ceramics at a low temperature as a wiring substrate material capable of simultaneously firing u and the like.

At present, with the progress of high-frequency circuit technology, high-frequency circuit elements such as resonators, couplers, and filters utilizing high-frequency transmission lines and their line wavelengths have become widespread by using wiring substrates made of various glass ceramics. However, the required characteristics are that, with respect to miniaturization, the relative dielectric constant is large, the dielectric loss at high frequencies is small, in other words, the Q value is large, and the change of the resonance frequency with respect to temperature changes. For example, it is small, and for reliability, it is chemically stable and has high mechanical strength.

If the above various characteristics are not satisfied, for example,
BaO-TiO ₂ based materials, BaO-rare earth oxide -
TiO ₂ -based materials and the like are known, and particularly CaTiO ₃ · La ₂ Ti ₂ O ₇ · Nd (M has a high dielectric constant and a low dielectric loss tangent and are used for microwave circuit boards and the like.
g _0.5 Ti _0.5 ) O ₃ .MgTiO ₃ .ZnO and the like have been proposed (see Japanese Patent Publication No. 3-3628).

[0012]

However, the above-mentioned proposed CaTiO ₃ .La ₂ Ti ₂ O ₇ .Nd (Mg _0.5
Ti _0.5 ) O ₃ .MgTiO ₃ .ZnO needs to be fired at a high temperature of 1200 to 1500 ° C. in order to be densely sintered alone. As described above, the conductor resistance is limited to refractory metals such as tungsten (W) and molybdenum (Mo) having a large conductor resistance. As a result, as in the above-described conventional technique, a large conductor resistance causes a large signal transmission loss in a high frequency region. There is a problem that it cannot be applied to a multilayer wiring board with a built-in capacitor, a multilayer wiring board with a filter, etc., which is used in a high frequency region and is required to be further downsized.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to have NdAlO ₃ which has a high dielectric constant and a low dielectric loss tangent and is used for a dielectric resonator or the like.
By using a CaTiO ₃ based material, a dense sintered body having a relative dielectric constant of at least 20 and a low dielectric loss tangent in a high frequency region and having a firing temperature of 1000 ° C. or less can be obtained. Together with C by co-firing
A low-temperature fired porcelain composition suitable for a wiring board material such as a multilayered wiring board with a built-in capacitor for high frequency and a smaller size, which can be multilayered using u, Ag, Au, etc. as a wiring conductor. To provide.

[0014]

Means for Solving the Problems The inventors of the present invention have made earnest studies on the above problems, and as a result, in order to obtain a dense glass-ceramic sintered body having a relative dielectric constant of more than 20, a high dielectric constant and a low dielectric loss tangent were used. As a result of focusing on the fluidity of the glass and the wettability of the glass with respect to the filler in order to increase the ratio of the amount of the filler to the glass by mixing the NdAlO ₃ · CaTiO ₃ based material having the The lower the softening point of glass as an influence,
The present invention has been accomplished by finding that the fluidity and wettability are excellent at low temperature, and the amount ratio of filler can be increased.

That is, the low temperature fired porcelain composition of the present invention comprises 9
B ₂ O ₃ —ZnO—SiO ₂ —Na ₂ O—Al ₂ O, which is a sintered body that densifies at a firing temperature of 00 to 1000 ° C. and has a composition of 10 to 30 wt% and a softening point of about 560 ° C. ₃ system glass, 1 to 10% by weight of Li in terms of oxide, and 66
To 86 consists of a percent by weight of NdAlO ₃ · CaTiO _3,
The obtained sintered body has a dielectric constant exceeding 20 and 200 MPa
It is characterized by showing the above-mentioned bending strength.

Further, the B ₂ O ₃ --ZnO--SiO _2-
Na ₂ O-Al ₂ O ₃ based glass is 15 to 25% by weight,
Li is 2 to 7% by weight in terms of oxide, and NdAlO ₃ .C
More preferably, the aTiO ₃ content is 70 to 80% by weight.

[0017]

According to the low temperature fired porcelain composition of the present invention, B ₂ O
_{3 -ZnO-SiO 2 -Na 2 O} -Al 2 O 3 based glass, in a non-lead glass, when heated by dispersing the glass in the filler particles from having a softening point of the lowest about 560 ° C., It will flow at a low temperature to wet the filler and fill the voids between the fillers in small amounts.

When Li is used as the filler, the softening point of the glass is further lowered and the action of the glass is further promoted.

On the other hand, NdAlO ₃ used as a filler
-CaTiO ₃ itself has a relative permittivity of 40 to 50 and a dielectric loss tangent of about 2 x 10 ^{-4. Even if} the relative permittivity of the glass is about 5, the composition ratio of both is By selecting and suppressing decomposition of NdAlO ₃ · CaTiO ₃ by reaction, the glass and NdAlO ₃ · CaTiO ₃
The relative permittivity of the glass-ceramic made of ₃ exceeds 20, and the dielectric loss tangent can be reduced.

Therefore, as compared with the conventional glass-ceramic wiring board having a relative permittivity of about 10, the wiring length is inversely proportional to the square root of the relative permittivity, and the wiring area is inversely proportional to the relative permittivity. When the relative permittivity is 20 or more, the wiring length can be reduced to about ⅔ or less and the wiring area can be reduced to about ½ or less, so that miniaturization can be realized.

Further, the glass and NdAlO ₃ .CaT
When only iO ₃ is fired, a dense sintered body cannot be obtained, but as described above, Li added as a filler has a function of lowering the softening point of glass and promotes densification, resulting in densification at low temperature. As a result, an excellent sintered body can be obtained, and as a result, 90
Cu, Ag, Au conductor material 3 at low temperature of 0 ~ 1000 ℃
Since both can be fired at the same time, it is possible to easily achieve fine wiring of a multilayer wiring board or the like equipped with these wiring conductors.
A smaller board can be realized.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the low temperature fired porcelain composition of the present invention, B ₂ O ₃ —ZnO—SiO having a softening point of about 560 ° C.
_{When the} content of ₂ -Na ₂ O-Al ₂ O ₃ based glass is less than 10% by weight, the voids between the filler particles cannot be filled with the glass even if other components are within a predetermined range, resulting in poor sintering, A dense sintered body cannot be obtained, and conversely, if it exceeds 30% by weight, oversintering occurs and voids are generated, which also does not become a dense sintered body.

Therefore, the amount of the glass is specified to be 10 to 30% by weight, and particularly 15 to 25% by weight from the viewpoint of sinterability.
Is more desirable.

Further, the glass and NdAlO ₃ .CaT
Even if the amount of iO ₃ is within the respective predetermined ranges, if Li is not contained, the softening point of the glass does not decrease, the voids between the filler particles cannot be filled with a small amount of glass, and if it exceeds 10% by weight, it is overbaked. As a result, voids are formed and the sintered body is not densified.

Therefore, the amount of Li is 1 to 0 in terms of oxide.
It becomes 10% by weight, more preferably 2 to 7% by weight.

On the other hand, if the amount of NdAlO ₃ · CaTiO ₃ is less than 66 wt%, the dielectric constant is lower than 20 causes excessive sintering because the glass amount is too large, 86
If the amount exceeds 5% by weight, the amount of glass is too small, resulting in poor sintering, and the dielectric loss tangent becomes large in any case.

Therefore, the NdAlO ₃ .CaTiO _{3 is}
The amount is specified to be 66 to 86% by weight, and 70 to 80% by weight is more preferable in terms of dielectric properties and densification.

Next, when the firing temperature is lower than 900 ° C., sintering fails even when the raw material content is a predetermined amount.
In addition, in either case, the relative dielectric constant is small and the dielectric loss tangent is large, and it is impossible to perform simultaneous firing using a conductor material such as Cu, Ag or Au.

When a wiring board is produced using such a low-temperature fired porcelain composition, for example, a mixture of raw material powders is used for forming an insulating layer according to a known tape forming method, that is, a doctor blade method or a rolling method. Mold the green sheet.

Next, as a metallization for the wiring layer on the surface of the green sheet, powder of Cu, Ag, Au, especially C
A wiring pattern is formed by means of screen printing, gravure printing, offset printing or the like using a metal paste containing u powder, and a through hole is formed in the green sheet if necessary, and the paste is placed in the through hole. The wiring layer and the insulating layer can be fired at the same time by filling and then laminating and pressing a plurality of green sheets, and then firing at the firing temperature in a non-oxidizing atmosphere such as N ₂ or Ar gas.

[0031]

EXAMPLES The low temperature fired porcelain composition of the present invention will be described in detail below. First, B ₂ O ₃ —ZnO—SiO ₂ —N having an average particle size of 5 μm or less and a softening point of about 560 ° C.
a ₂ O—Al ₂ O ₃ based glass, Li carbonate having an average particle size of 10 μm or less, and 60% by volume of NdAlO ₃ and 4
NdAlO ₃ .CaT having an average particle size of 5 μm or less obtained by wet mixing 0 vol% CaTiO ₃ , dried, then calcined at 1300 to 1400 ° C., and then wet pulverized again.
Raw material powders of iO ₃ were mixed according to the composition shown in Table 1.

Then, an organic binder, a plasticizer, and an organic solvent are added to the mixture to prepare a slurry, and the slurry is dried and mesh-passed to prepare a molding powder, and then the molding powder is prepared. Press formed to a thickness of about 6.5 mm
There were obtained two types of molded products, a cylindrical one and a flat plate-shaped one.

The molded body thus obtained was placed in the atmosphere at 45
The binder was removed at a temperature of 0 ° C. and then fired under the conditions shown in Table 1 to obtain a sintered body of the low temperature fired porcelain composition.

[0034]

[Table 1]

Sinterability, relative permittivity, and dielectric loss tangent were measured and evaluated by the following methods using the above-mentioned sintered body for evaluation.

First, the sinterability was evaluated by immersing the sample in a penetrant flaw detection liquid and visually inspecting the liquid for permeation.

On the other hand, for the relative dielectric constant and dielectric loss tangent, a sample having a diameter of 10 mm and a thickness of 5 mm was cut out from the sintered body, and
It was measured by a cylindrical resonator method using a network analyzer and a synthesized sweeper at -10 GHz.

Specifically, the dielectric substrate of the sample is sandwiched between copper plate jigs having a diameter of 50 mm for measurement, and TE01 of the resonator is measured.
The relative permittivity and dielectric loss tangent were calculated from the resonance characteristics of one mode.

The bending strength is 38 mm in length and 4 m in width from the flat plate-shaped sintered body according to JIS R1601 standard.
A 4-point bending bending test piece with m and a height of 3 mm was cut out and determined from a 4-point bending test with an upper span of 10 mm and a lower span of 30 mm.

[0040]

[Table 2]

As is clear from the results in the table, sample numbers 1, 8, 9, 14, 15, 1 which are outside the scope of the present invention are claimed.
Nos. 9 and 20 have poor sinterability at a firing temperature of 900 to 1000 ° C., and have a low strength of less than 200 MPa. In particular, Sample Nos. 1, 8 and 19 cannot measure the dielectric properties, and Sample Nos. Sample No. 23, which has satisfactory sinterability, has an insufficient strength of less than 200 MPa, and Sample No. 15 has a relative dielectric constant of less than 20, which does not achieve the intended purpose.

On the other hand, in the present invention, all are 900
It has been sufficiently sintered at a firing temperature of up to 1000 ° C, has a high strength of 200 MPa or more, and has a relative dielectric constant of 20.7 or more.

[0043]

As described in detail above, since the low temperature fired porcelain composition of the present invention has a relative dielectric constant of 20 or more and a dense sintered body having a small dielectric loss tangent in a high frequency region, various wiring boards can be obtained. As a result, fine wiring is possible, and since the sintered body has high strength, there is no problem in various works when mounting chip resistors, semiconductor elements, etc. Can be used on top of that,
Since it can be fired at a low temperature of 900 to 1000 ° C., a wiring made of Cu, Ag, Au or the like having a low conductor resistance can be formed by simultaneous firing, and a multilayered, more compact capacitor for high frequency can be formed. A low temperature fired porcelain composition suitable as a wiring board material such as a built-in multilayer wiring board and a filter-embedded multilayer wiring board can be obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-8-77829 (JP, A) JP-A-7-182922 (JP, A) JP-A-3-45556 (JP, A) JP-A-6- 76633 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 35/42-35/50 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A zinc borosilicate type (B ₂ O ₃ —ZnO—S
iO ₂ —Na ₂ O—Al ₂ O ₃ type glass is 10 to 30
% By weight, 1 to 10% by weight of lithium (Li) in terms of oxide, and 66 to 8 of composite oxide of neodymium aluminate and calcium titanate (NdAlO ₃ .CaTiO ₃ ).
A sintered body comprising 6% by weight and densified at a firing temperature of 900 to 1000 ° C., characterized in that the relative dielectric constant of the sintered body exceeds 20, and the flexural strength is 200 MPa or more. Low temperature fired porcelain composition. 2. The zinc borosilicate type (B ₂ O ₃ --ZnO)
_{-SiO 2 -Na 2 O-Al 2} O 3 system) glass 15
25% by weight and lithium (Li) 2 to 7 in terms of oxide
70% by weight of the composite oxide (NdAlO ₃ · CaTiO ₃ ) of neodymium aluminate and calcium titanate.
The low temperature fired porcelain composition according to claim 1, which is composed of 80% by weight.