JPH06326429A - Composition for ceramic board - Google Patents

Abstract

PURPOSE:To make it possible to fire the title composition at a very low temperature, to use paste as an inner electrode, and to satisfy various kinds of characteristics requied for a calcined body by a method wherein the above- mentioned composition is composed of glass frit of specific weight percent and the solid solution consisting of strontium titanate and calcium titanate. CONSTITUTION:The title composition for a ceramic board is composed of glass frit of 60 to 95wt.% consisting of Al2O3 of 50 to 60wt.%, SiO2 of 25 to 30wt.%, PbO of 7.8 to 8.3wt.%, CaO of 3.3 to 3.8wt.%, B2O3 of 2.5 to 3.0wt.%, MgO of 1.1 to 1.5wt.%, Na2O of 1.1 to 1.5wt.% and K2O of 0.8 to 1.1wt.%, and the solid solution of 5 to 40wt.% consisting of strontium titanate and calcium titanate. The solid solution consists of strontium titanate of 55 to 75mol% and calcium titanate of 25 to 45mol%. In the above-mentioned constitution, the adding quantity of Al2O3 is small, and a titanate solid solution, having high reactivity with glass frit, is used. As a result, firing temperature can be decreased remarkably.

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, which is suitable for a multilayer wiring substrate for forming electronic circuits such as conductors and resistors in multiple layers.

[0002]

2. Description of the Related Art In recent years, multilayer wiring boards having electronic circuits formed in multiple layers have been used in various electric devices. The following two types of methods are used to manufacture a ceramic substrate for multilayer wiring. The first method is a method in which a circuit and an insulating layer are alternately printed on a ceramic substrate obtained by firing a composition for a ceramic substrate prepared for multilayer wiring, and the resulting product is fired to produce the second method. Is a method in which a circuit is printed on an unfired ceramic substrate, the circuits are laminated so that the circuits do not contact each other, 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 to form a high-density integrated circuit. You can do it. The composition for the ceramic substrate used for the multilayer wiring of the second method includes Al ₂ O ₃ powder and 1
It is known that 5 wt% or less of glass powder is fixed with an inorganic binder, and that a mixture of a lead compound and a boron compound is mixed in an Al ₂ O ₃ —SiO ₂ system and fired at a low temperature.

[0003]

However, in the above conventional structure, the Al ₂ O ₃ powder of the second method and the glass powder of 15 wt% or less fixed by an inorganic binder have a firing temperature of 1450 to 1600 ° C. There was a problem that the workability and productivity were extremely high. In addition, as the material for forming the circuit, it is necessary to use expensive materials such as Mo and W that do not deteriorate at this firing temperature, resulting in high cost.
There was a problem that the material had to be fired in a reducing atmosphere, and the material selectivity and mass productivity were lacking. Al ₂ O ₃ -Si
The O ₂ system mixed with a lead compound or a boron compound in an amount of 10 wt% or more and fired at a low temperature has a problem that the rate of change in capacitance with temperature change (hereinafter referred to as TCC) is large and lacks reliability. .

The present invention solves the above-mentioned problems of the prior art. It can be fired at an extremely low temperature of 750 to 950 ° C.
Various properties such as volume resistivity, dielectric constant, dielectric loss tangent, dielectric breakdown strength, bending strength, etc. as a substrate for multi-layer wiring that can use paste of u, Ag, Ag-Pd, Cu, etc. as internal electrodes Is satisfied, and TCC is ± 0p
It is an object to provide a composition for a ceramic substrate that can be adjusted to pm / ° C to ± 100 ppm / ° C.

[0005]

In order to achieve this object, the composition for a ceramic substrate according to claim 1 of the present invention has a composition of wt%, Al ₂ O ₃ of 50 to 60, S.
iO ₂ is 25 to 30, PbO is 7.8 to 8.3, CaO
Is 3.3 to 3.8, B ₂ O ₃ is 2.5 to 3.0, MgO
1.1-1.5, Na ₂ O 1.1-1.5, K ₂ O
Glass frit 60 consisting of 0.8 to 1.1
95 wt% and a solid solution of strontium titanate and calcium titanate 5 to 40 wt%.

A composition for a ceramic substrate according to a second aspect is the composition according to the first aspect, wherein the solid solution comprises 55 to 75 mol% strontium titanate and 25 to 45 mol% calcium titanate. is doing.

Here, the glass frit has a content rate of 6
If it is less than 0 wt%, the firing temperature will be high, while if it exceeds 95 wt%, the bending strength and moisture resistance of the fired product will be reduced, which is not preferable. Moreover, adjustment of TCC becomes difficult. If the content of SiO ₂ which is a constituent of the glass frit is less than 25 wt%, the softening temperature becomes low and a large deformation is likely to occur during firing. If it exceeds 30 wt%, the firing temperature becomes too high, which is not preferable. PbO is preferably added in an amount of 7.8 wt% or more in order to improve the melting property of glass. However, if the addition amount exceeds 8.3 wt%, the softening temperature of the glass tends to be low, and large deformation tends to occur during firing, which is not preferable. CaO is added for the purpose of improving the meltability during the production of glass frit and adjusting the thermal expansion coefficient of glass. Addition amount is 3.3wt
If it is less than%, the meltability is not improved and devitrification tends to occur during frit production. Also, the addition amount is 3.8 wt%
If the amount is larger, the coefficient of thermal expansion tends to be too large, and thus both are not preferable. B ₂ O ₃ is a flux, and if the addition amount is less than 2.5 wt%, the firing temperature tends to be too high, and if it exceeds 3.0 wt%, the chemical stability of the glass tends to be lowered, so both are preferred. Absent. M
gO is added for the purpose of improving the meltability during the production of glass frit and adjusting the coefficient of thermal expansion of glass. If the addition amount is less than 1.1 wt%, the meltability is not improved and devitrification tends to occur during frit production, and if it exceeds 1.5 wt%, the thermal expansion coefficient tends to be too large. Absent. Na ₂ O is added for the purpose of improving the solubility of glass, and it is desirable that Na ₂ O be added in an amount of 1.1 wt% or more. However, if the addition amount exceeds 1.5 wt%, 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 added for the purpose of improving the melting property of glass, and is 0.
It is desirable to add 8 wt% or more. However, if the addition amount exceeds 1.1 wt%, 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 added for the purpose of improving the mechanical strength of ceramics, and is preferably added in an amount of 50 wt% or more. However, if the addition amount exceeds 60 wt%, the firing temperature becomes too high, which is not preferable.

In the titanate solid solution of SrTiO ₃ and CaTiO ₃ , when SrTiO ₃ is less than 55 mol%, the formation of the solid solution becomes heterogeneous, and when the TCC is adjusted using this solid solution, a linear change occurs. Not shown, TCC is positive at -25 ° C to + 20 ° C, and positive at + 20 ° C to + 85 ° C.
Since it shows a negative value, it tends to be difficult to adjust. The same tendency is observed when SrTiO ₃ exceeds 75 mol%.

[0009]

With this configuration, the firing temperature can be remarkably lowered by using the titanate solid solution having a small amount of Al ₂ O ₃ added and having high reactivity with the glass frit. In addition, since the firing temperature is low, it is possible to use pastes such as Au, Ag, Ag-Pd, and Cu that are widely used in thick film technology. Further, mechanical strength such as bending strength of the fired body and heat conduction can be used. It is possible to improve the sex. Further, it is possible to improve electric characteristics such as a small dielectric constant and a large insulation resistance, and improve the moisture resistance. Especially glass frit with negative TCC characteristics and negative TCC
TCC by firing reaction of titanate solid solution system with characteristics
Can be easily adjusted.

[0010]

EXAMPLE 1 Example 1 of the present invention
explain. The production of glass frit is shown in (Table 1).
Sea urchin in weight percent, SiO₂Is 27, PbO is 8.1, Ca
O is 3.5, B ₂O₃2.7, MgO 1.3, Na
₂O is 1.3, K₂So that O has a composition of 1.1,
Mix each raw material according to the usual method, and
Melt while stirring at a certain degree, and after melting, granulate or flake
And then add Al₂O₃55% by weight
It was Next, this glass frit and SrTiO 3₃And Ca
TiO₃And a titanate solid solution consisting of
Weigh it to 0 wt% and 10 wt% and use a ball mill.
The mixture was pulverized and mixed to obtain the composition for ceramic substrate of this example.
Add 10 wt% of binder to this pulverized and mixed composition
After granulating and molding, the mixture was fired at 850 ° C. for 15 minutes. This grill
When the relative density of the adult was measured, it was 99.98%.
It was Then, after processing to a diameter of 30 mm and a thickness of 0.35 mm, A
When the g electrode was baked and the TCC was measured, it was -25 ° C.
It was ± 0 ppm / ° C at + 85 ° C. So this
Various binders, plasticizers, solvents in pulverized and mixed compositions
Is added and kneaded to form a paste having a viscosity of 10 ps to 30 ps.
It was made. Apply this paste to the conventional doctor blade method
Thus, a green sheet having a thickness of 0.1 mm was produced. this
Fifty green sheets are piled up, and then about 5 at 35 ℃
Thermocompression bonding at a pressure of 0 tons and baking at 850 ° C for 15 minutes
did. Then, various characteristics of the fired sheet were measured.
The results are shown in (Table 1). In addition, TCC (-25 ℃ ~
85 ° C.) ± 0 ppm / ° C.

[0011]

[Table 1]

(Comparative Examples 1 and 2) (Table 2) As shown in Table 2, mol% of SrTiO ₃ and CaTiO _{3 in} the titanate solid solution.
Was set to 50:50 (Comparative Example 1) and 80:20 (Comparative Example 2), and a green sheet was prepared in the same manner as in Example 1 and its characteristics were measured. The results are shown in (Table 2). It was found that the TCC was +120 ppm / ° C. or higher and was not practical.

[0013]

[Table 2]

(Example 2) The glass frit obtained in Example 1 and the titanate solid solution were weighed to be 94 wt% and 6 wt% respectively as shown in (Table 1), and the same as in Example 1. Then, the mixture was pulverized and mixed in a ball mill to obtain a green sheet fired body in the same manner. The firing temperature in this case is 800
It was ℃. Various characteristics of the fired sheet were measured, and the results are shown in (Table 1). The volume resistivity, the dielectric constant, the dielectric loss tangent, the dielectric breakdown strength, the bending strength, etc. were almost the same values as in Example 1. The TCC was +50 ppm / ° C.

(Example 3) The glass frit obtained in Example 1 and the titanate solid solution were weighed to 70 wt% and 30 wt%, respectively, as shown in (Table 1), and the same as in Example 1. Then, a green sheet fired body was obtained. Next, the characteristics of this fired body were measured, and the results are shown in (Table 1).
The firing temperature was 870 ° C. The volume resistivity, the dielectric constant, the dielectric loss tangent, the dielectric breakdown strength, the bending strength, etc. were substantially the same as those in Example 1. The TCC was -20 ppm / ° C.

(Example 4) The glass frit obtained in Example 1 and the titanate solid solution were weighed at 60 wt% and 40 wt% respectively as shown in (Table 1), and burned at the same temperature as in Example 1. At 920 ° C., a green sheet fired body was obtained.
Then, its characteristics were measured and the results are shown in (Table 1). The volume resistivity, the dielectric constant, the dielectric loss tangent, the dielectric breakdown strength, the bending strength, etc. were almost the same values as in Example 1. The TCC was -30 ppm / ° C. Furthermore, A
The same result was obtained when the characteristics of the fired body in which the pastes such as u, Ag-Pd, and Cu were used as the internal electrodes were measured.

Comparative Examples 3 and 4 Green sheets were obtained in the same manner as in Example 1 except that the mixing ratio of the glass frit obtained in Example 1 and the titanate solid solution was changed as shown in Table 2. , Its characteristics were measured. The results are shown in (Table 2).

(Comparative Examples 5 and 6) Green sheets were obtained in the same manner as in Example 1 except that the composition of the glass frit was out of the range of the present invention as shown in (Table 2), and the characteristics thereof were measured. The results are shown in (Table 2).

As is clear from (Table 1) and (Table 2), the composition for a ceramic substrate according to the present embodiment can be fired at an extremely low temperature as compared with the conventional composition,
It was also found that the mechanical properties and electrical properties were excellent and the TCC could be easily adjusted.

[0020]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to perform firing at an extremely low temperature, and it is possible to use a paste such as Au, Ag, Ag-Pd or Cu as an internal electrode.
Various required characteristics of the fired body, ie, volume resistivity, dielectric constant, dielectric loss tangent, dielectric breakdown strength, bending strength, etc., good ceramic substrate as a multilayer wiring board for forming electronic circuits such as conductors and resistors in multiple layers. Satisfies the characteristics of
C can also be adjusted to ± 0 ppm / ° C to ± 100 ppm / ° C, and it is possible to realize a composition for a ceramic substrate that is extremely low in cost and excellent in mass productivity.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. The composition of the composition is wt% and the content of Al ₂ O ₃ is 50 to 50%.
60, SiO ₂ is 25 to 30, PbO is 7.8 to 8.
3, CaO is 3.3 to 3.8, and B ₂ O ₃ is 2.5 to 3.
0, MgO is 1.1 to 1.5, and Na ₂ O is 1.1 to 1.
5. A ceramic substrate comprising 60 to 95 wt% of a glass frit composed of 0.8 to 1.1 of K ₂ O and 5 to 40 wt% of a solid solution of strontium titanate and calcium titanate. Composition. 2. The composition for a ceramic substrate according to claim 1, wherein the solid solution comprises 55 to 75 mol% strontium titanate and 25 to 45 mol% calcium titanate.