JPH07172911A - Composition for ceramic substrate - Google Patents

Abstract

PURPOSE:To obtain the subject composition favorable for multilayer wiring, i.e., forming multilayered electronic circuits for conductors, resistors, etc. CONSTITUTION:This composition comprises 60-95wt.% of glass frit and 5-40wt.% of a solid solution composed of strontium titanate and calcium titanate. The composition can be fired at 750-950 deg.C, and the fired product satisfies various characteristics such as for multilayer wiring boards capable of using Au, Ag, Ag-Pd, Cu, etc., as internal electrode and those to form in layers electronic circuits for conductors, resistors, etc., such as volume resistivity, dielectric constant, dissipation facto, dielectric breakdown strength, flexural strength, etc. Besides, this composition is easy to control so as to be + or -0ppm/ deg.C to + or -100ppm/ deg.C in TCC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a ceramic substrate used for a multilayer wiring substrate or the like in which electronic circuits such as conductors and resistors are formed in multiple layers.

[0002]

2. Description of the Related Art At present, as an electronic component for forming a circuit in multiple layers, a first method of manufacturing a circuit by alternately printing a circuit and an insulating layer on a fired alumina substrate, and baking the circuit, and a non-fired method. There is a second method in which the circuit is printed on the ceramic substrate, the circuits are laminated so that the circuits do not come into contact with each other, and the circuit is pressed and then fired. In the case of the first method, the insulating layer formed thereon has irregularities due to the influence of the circuit, and the unevenness becomes larger in the upper layer. When this unevenness becomes large, it becomes difficult to print the next circuit on it, and the limit is usually around 10 layers. On the other hand, in the second method, since the circuit printing is always performed on the substrate in a state close to a plane, it is possible to manufacture one having a large number of stacked layers and form a high-density integrated circuit. . The ceramic substrate composition used for the substrate of the second method includes Al ₂ O ₃ powder and glass powder of 15 wt% or less fixed with an inorganic binder, or Al ₂ O ₃ -Si.
There is an O ₂ system mixed with Pb and B and baked at a low temperature.

[0003]

However, the Al ₂ O ₃ powder of the second conventional method and the glass powder of 15 wt% or less fixed by an inorganic binder have an extremely high firing temperature of 1450 to 1600 ° C. Therefore, as the material for forming the circuit, expensive materials such as Mo and W that do not deteriorate at this firing temperature are used, and since it is necessary to fire in a reducing atmosphere, workability is poor. A material obtained by mixing Pb or B in an Al ₂ O ₃ —SiO ₂ system at about 10 wt% and firing at a low temperature has a problem that the rate of change in capacitance with temperature change (hereinafter referred to as TCC) is large.

The present invention solves the above-mentioned conventional problems, and can be fired at an extremely low temperature, that is, 750 to 950 ° C., and uses a paste of Au, Ag, Ag-Pd, Cu or the like as an internal electrode. In addition, the volume specific resistance, the dielectric constant, the dielectric loss tangent, the dielectric breakdown strength, the bending strength, etc., satisfy the various characteristics as a multilayer wiring board for forming electronic circuits such as conductors and resistors in multiple layers. TCC is ± 0
The present invention provides a composition for a ceramic substrate that can be adjusted to ppm / ° C to 100 ppm / ° C.

[0005]

A composition for a ceramic substrate of the present invention for solving this problem is expressed in wt%.
Glass frit 60-95, SrTiO ₃ and CaTiO
_The composition for a ceramic substrate comprising the solid solutions 5 to 40 of _{3, wherein} the solid solution is represented by mol% SrTiO ₃
55 to 75, CaTiO ₃ 25 to 45.
Further, the glass frit is essentially composed of Al ₂ O ₃ at wt%.
_{40~50, SiO 2 25~30, ZnO 5~15} ,
TiO ₂ 5-15, CaO 3.3-3.8, B ₂ O ₃
2.5-3.0, MgO 1.1-1.5, Na ₂ O
It has a structure consisting of 1.1 to 1.5 and K ₂ O 0.8 to 1.1.

If the glass frit is less than 60 wt%, the firing temperature will be high, and it will be difficult to perform firing at a low temperature, which is the subject of the present invention. On the other hand, when the glass frit is more than 95 wt%, the bending strength and moisture resistance of the fired product are deteriorated, which is not preferable. In addition, it becomes difficult to adjust the TCC.

If the SiO ₂ content is less than 25 wt%, the softening temperature becomes low and a large deformation occurs during firing, resulting in 30 wt%.
If it is more than%, the firing temperature becomes too high, which is not preferable.

ZnO is preferably added in an amount of 5 wt% or more in order to improve the solubility of glass. If it is more than 15 wt%, the softening temperature of the glass tends to be too low, and large deformation tends to occur during firing, which is not preferable.

TiO ₂ is preferably added in an amount of 5 wt% or more in order to improve the melting property and chemical stability of glass.
If it is more than 15 wt%, the softening temperature of the glass becomes high,
The firing temperature becomes too high, which is not preferable.

CaO is added for the purpose of improving the meltability during the production of glass frit and adjusting the coefficient of thermal expansion of glass. When it is less than 3.3 wt%, the meltability is not improved,
Devitrification is likely to occur during frit production. When it is more than 3.8 wt%, the coefficient of thermal expansion becomes too large, which is not preferable.

B ₂ O ₃ is a flux, 2.5 w
If it is less than t%, the firing temperature becomes too high and 3.0w
If it is more than t%, the chemical stability of the glass is lowered and both are not preferable.

MgO is added for the purpose of improving the meltability during the production of glass frit and adjusting the thermal expansion coefficient of glass. If it is less than 1.1 wt%, the meltability is not improved,
Devitrification is likely to occur during frit production. If it exceeds 1.5 wt%, the coefficient of thermal expansion becomes too large, which is not preferable.

Na ₂ O is preferably added in an amount of 1.1 wt% or more in order to improve the glass solubility. 1.5w
If it is more than t%, the softening temperature of the glass tends to be too low, and large deformation tends to occur during firing, which is not preferable.

K ₂ O is preferably added in an amount of 0.8 wt% or more in order to improve the melting property of glass. 1.1 wt
If it is more than%, the softening temperature of the glass tends to be too low, and large deformation tends to occur during firing, which is not preferable.

Al ₂ O ₃ is preferably added in an amount of 40 wt% or more in order to improve the mechanical strength of ceramics.
If the addition amount is 50 wt% or less, the firing temperature becomes too high,
Not preferable.

The solid solution of SrTiO ₃ and CaTiO ₃ is
Mol%, SrTiO ₃ 55-75, CaTiO ₃ 25
~ 45 is desirable. When SrTiO ₃ and CaTiO ₃ are 55 or less and 45 or more, respectively, when the TCC is adjusted using this solid solution due to the formation of an inhomogeneous solid solution, there is no linear change, and the TCC is -25 ° C
It is difficult to adjust because it is positive at + 20 ° C and negative at + 20 ° C to + 85 ° C. SrTiO ₃ and CaT
The same applies when iO ₃ is 75 or more and 25 or less, respectively.

[0017]

With this configuration, it is possible to perform firing at a temperature extremely lower than the conventional one, that is, 750 to 950 ° C., and pastes such as Au, Ag, Ag—Pd, Cu which are widely used in thick film technology are applied as internal electrodes. In addition, the fired body has a large bending strength, an excellent thermal conductivity, a relatively small dielectric constant, a large insulation resistance, and an excellent moisture resistance, and particularly a glass frit having a positive TCC characteristic. Negative T
By the firing reaction of titanate solid solution having CC characteristics,
Adjustment of TCC can be facilitated.

[0018]

EXAMPLES Examples of the present invention will be described below.

First, the glass frit is made of SiO 2 in wt%.
_{2 27, ZnO 8.0, TiO 2} 8.0, CaO
3.6, B ₂ O ₃ 2.8, MgO 1.4, Na ₂ O
Each raw material was blended by a usual method so as to have a composition of 1.3, K ₂ O 0.9, melted with stirring at a temperature of 1400 to 1500 ° C., and then melted or granulated or flaked. Then, 47 wt% of Al ₂ O ₃ was added thereto to manufacture a glass frit. Next, this glass frit and Sr
A titanate solid solution containing TiO ₃ and CaTiO ₃ was weighed so as to be 90 wt% and 10 wt%, respectively, and pulverized and mixed with a ball mill to obtain a composition of the present invention. To this pulverized and mixed composition, 10 wt.
%, Added, granulated, molded, and fired at 900 ° C. for 15 minutes.
When the relative density of this fired body was measured, it was 99.98%
Therefore, after processing to a diameter of 30 mm and a thickness of 0.35 mm, an Ag electrode was baked and the TCC was measured.
It was ± 0 ppm / ° C at 25 ° C to + 85 ° C. Then, various binders, plasticizers, and solvents were added to the pulverized and mixed composition and kneaded to prepare a paste having a viscosity of 10 ps to 30 ps. This paste was made into a green sheet having a thickness of 0.05 mm by a conventional doctor method. 50 sheets of this green sheet are piled up, and then about 5 at 35 ℃
It was thermocompression bonded at a pressure of 0 ton and baked at 900 ° C. for 15 minutes. Various characteristics of the fired sheet were measured, and the volume specific resistance was 10 ^{14 to 16} Ω, the dielectric constant was 9.8, and the dielectric loss tangent was ≦ 5.
× 10 ^-4 , dielectric breakdown strength 700 to 900 kV / cm, bending strength 2000 to 2500 kg / cm ² , TCC (-2
5 ° C to + 85 ° C) ± 0 ppm / ° C. That is, the results satisfying the characteristics of a good ceramic substrate as a multilayer wiring substrate in which electronic circuits such as conductors and resistors are formed in multiple layers were obtained.

Further, the glass frit and SrTi
The titanate solid solution consisting of O ₃ and CaTiO ₃ was weighed so as to be 94 wt% and 6 wt%, respectively, pulverized and mixed by a ball mill, and a green sheet fired body was obtained by the above method. The firing temperature in this case was 800 ° C. When various characteristics of the fired sheet were measured, volume resistivity, dielectric constant, dielectric loss tangent, dielectric breakdown strength, bending strength, etc. were the same as above. + 50pp for TCC
It was m / ° C. Glass frit, SrTiO ₃ and C
The titanate solid solution composed of aTiO ₃ is 7
In the case of 0 wt% and 30 wt%, the volume resistivity, the dielectric constant, the dielectric loss tangent, the dielectric breakdown strength, the bending strength, etc., obtained at the firing temperature of 870 ° C. were equivalent to the above values. TCC is
It was −20 ppm / ° C. Glass frit and SrT
A titanate solid solution composed of iO ₃ and CaTiO ₃ ,
For 60 wt% and 40 wt% respectively, firing temperature is 9
At 20 ° C., the volume specific resistance, dielectric constant, dielectric loss tangent, dielectric breakdown strength, bending strength, etc. were the same values as above. TC
C was −30 ppm / ° C. Furthermore, Au, A
g, Ag-Pd, Cu, etc. as the internal electrodes,
Similar results were obtained for the laminated fired bodies. The above results are shown in (Table 1) to (Table 4).

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

As can be seen from (Table 1) to (Table 4), the present invention is capable of firing at an extremely low temperature as compared with conventional compositions, and has excellent mechanical properties and electrical properties, T
It has been found that adjustment of CC is easy.

[0026]

As described above, according to the present invention, the firing can be realized at an extremely low temperature, that is, 750 to 950 ° C., and the paste of Au, Ag, Ag—Pd, Cu or the like is used as the internal electrode. It is now possible to use. Furthermore, various required characteristics of the fired body, that is, volume specific resistance, dielectric constant, dielectric loss tangent, dielectric breakdown strength, bending strength, etc., are excellent as a multilayer wiring board for forming electronic circuits such as conductors and resistors in multiple layers. Since the characteristics of the ceramic substrate are satisfied and the TCC is easily adjusted to ± 0 ppm / ° C. to ± 100 ppm / ° C., it is possible to realize a composition for a ceramic substrate capable of significantly reducing the cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H05K 3/46 H 6921-4E (72) Inventor Koichi Watanabe 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Sangyo Co., Ltd.

Claims (3)

[Claims] 1. Glass frit 60-9 in wt% display.
5. A composition for a ceramic substrate comprising a solid solution 5 to 40 of strontium titanate (hereinafter referred to as SrTiO ₃ ) and calcium titanate (hereinafter referred to as CaTiO ₃ ). 2. The solid solution is SrTiO _{3 in} mol%.
55 to 75, CaTiO _3, characterized in that it consists of 25 to 45 claims 1 ceramic substrate composition according. 3. The glass frit is essentially wt% Al ₂ O ₃ 40-50, SiO ₂ 25-30, Zn.
O 5-15, TiO ₂ 5-15, CaO 3.3-
_{3.8, B 2 O 3 2.5~3.0,} MgO 1.1~
1.5, Na ₂ O 1.1 to 1.5, K ₂ O 0.8 to
1. The composition for ceramic substrates according to claim 1, which is composed of 1.