JPH0992978A - Glass ceramic board with built-in capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an insulator material component from diffusing into a dielectric layer in case of firing surely by forming a barrier layer of a refractory of a specific metal oxide, for suppressing the diffusion of a glass component between capacitor electrodes and a glass ceramic insulating layer. SOLUTION: On the occasion of manufacturing a glass ceramic multilayer interconnection board with built-in capacitor, electrodes 21 and a dielectric layer 22, and barrier layers 4 and via-conductors 3 of a capacitor 2, furthermore according to need a desired wiring pattern are formed beforehand in a plurality of glass ceramic green sheets constituting insulating layer 1, and then those glass ceramic green sheets are laminated and fired. As the barrier layers 4, one kind of powder or more chosen from refractory powders of alumina, magnesia, zirconia, titania, calcia are used. To that powder a binder for example is mixed and kneaded to make paste, and a barrier layer is formed by printing between the capacitor electrodes and the insulating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass ceramic substrate having a built-in capacitor, and more particularly to a glass ceramic substrate having a built-in capacitor obtained by simultaneously firing a glass ceramic insulating layer, a capacitor electrode, and other circuit wiring.

[0002]

2. Description of the Related Art Built-in capacitors obtained by forming a predetermined pattern using Ag paste and capacitor paste on a green sheet made of a mixture of glass powder and ceramic filler, laminating a plurality of sheets and firing at 800 to 1000 ° C. There is a glass ceramic substrate (multilayer wiring substrate). Such a glass-ceramic substrate with a built-in capacitor is expected to contribute to the miniaturization of electronic devices because it can be made smaller and higher in density than a capacitor with a lead or a chip capacitor soldered on the substrate. There is.

Conventionally, in a ceramic multilayer wiring board with a built-in capacitor, as a material used for the capacitor, a lot of researches have been conducted on a material mainly composed of a lead perovskite type composite material which can be fired at a low temperature. As a typical example, for example, Pb (Mg _1/3 Nb _2/3 )
O ₃ , Pb (Fe _1/2 Nb _1/2 ) O ₃ , Pb (Fe _2/3
There are materials such as W _1/3 ) O ₃ and their dielectric constants are as high as 12000, 24000 and 20000, respectively.

[0004]

However, when the above-mentioned conventional lead perovskite composite material is incorporated into a glass ceramic substrate, a glass component such as boron oxide or silica diffuses into the dielectric layer during firing, and after firing, In some cases, the above capacitor did not satisfy the desired dielectric characteristics. For example, a lead perovskite composite material Pb (Mg _1/3 Nb
The dielectric constant of _2/3 ) O ₃ is 12000 as above by itself.
However, if it is built in the low temperature firing substrate, it will be reduced to about 30.

As a method for improving this, a method has conventionally been proposed in which a barrier layer is provided between the capacitor electrode and the glass ceramic insulating layer by printing or the like to suppress diffusion. For example, a method of forming an intermediate layer made of a dielectric material different from the dielectric composition to form a barrier layer (see, for example, JP-A 1-2).
No. 62695), and a method of providing a metal intermediate layer (see, for example, JP-A-62-265795). There is also a method of suppressing diffusion by adding glass powder to the electrode layer (for example, see JP-A-7-111225).

However, the above-mentioned conventional ones cannot necessarily suppress the diffusion of the insulating material component made of glass ceramic, especially the glass component, into the dielectric layer at the time of firing, resulting in a high dielectric constant and a dielectric loss. It is difficult to obtain a ceramic substrate with a built-in capacitor that is low in power consumption, the cost is high to form the barrier layer, and the electrical characteristics of the capacitor change due to the addition of additives to the electrode layer. was there.

The present invention has been proposed in view of the above problems, and is provided with a barrier layer capable of reliably suppressing the diffusion of the insulating material components into the dielectric layer during firing, and has a high dielectric constant. An object of the present invention is to provide a glass-ceramic multilayer wiring board with a built-in capacitor with low dielectric loss at low cost.

[0008]

In order to achieve the above object, a glass ceramic substrate with a built-in capacitor according to the present invention has the following constitution. That is, in a glass ceramic substrate with a built-in capacitor obtained by simultaneously firing a glass ceramic insulating layer, a capacitor electrode, and other circuit wiring, alumina, magnesia, which suppresses the diffusion of glass components between the capacitor electrode and the glass ceramic insulating layer, 1 selected from zirconia, titania and calcia
It is characterized in that a barrier layer made of at least one kind of refractory material is formed.

[0009]

By forming the barrier layer made of a refractory material such as alumina between the capacitor electrode and the glass ceramic insulating layer as described above, the diffusion of the glass component into the dielectric layer during firing is suppressed, It is possible to provide a glass ceramic substrate with a built-in capacitor, in which a decrease in the dielectric constant of the dielectric layer is prevented and which has a high dielectric constant and excellent dielectric properties.

[0010]

1 is a cross-sectional view after firing showing an example of a specific structure of a glass ceramic substrate with a built-in capacitor (multilayer wiring substrate) according to the present invention. In the figure, 1
Is an insulating layer made of glass ceramic and 2 is a capacitor. The capacitor 2 is composed of a pair of electrodes 21 and a dielectric layer 22 interposed between the electrodes 21 and 21.
Reference numeral 3 is a via conductor conductively connected to each of the electrodes 21 and 4 is a barrier layer.

In manufacturing a glass ceramic multilayer wiring board having a built-in capacitor as described above, for example, a plurality of glass ceramic green sheets forming the insulating layer 1 are preliminarily formed on the electrodes 21 and the dielectric layer 22 of the capacitor 2.
After forming the barrier layer 4, the via conductor 3 and a desired wiring pattern not shown in the drawing as necessary, these glass ceramic green sheets are laminated and fired.
In this case, in the capacitor 2, for example, the barrier layer 4 and the electrode 21 are sequentially formed by printing or the like on the ceramic green sheet, and then the dielectric paste to be the dielectric layer 22 is formed thereon by printing or the like. The electrode 21 and the barrier layer 4 are sequentially formed on the top by printing or the like. Further, the via conductor 3 may be formed by filling the conductor paste after forming the via hole.

The glass ceramic powder used for the above glass ceramic green sheet is, for example, 1100.
A material that can be sufficiently sintered at a temperature of ℃ or below may be used, and the material thereof is appropriate, and examples of the glass powder include alumino-boron containing lead oxide, zinc oxide, alkaline earth metal oxides, alkali metal oxides and the like. Silica glass with a softening point of 600-
Amorphous glass powder at 800 ° C, or 600 to 110
Crystallized glass that crystallizes at 0 ° C. can be used. Further, a ceramic filler such as alumina, zircon, mullite, cordierite, anorthite or silica may be mixed therewith. In that case, the mixing ratio may be appropriately adjusted in consideration of performances such as folding strength, dielectric constant, and denseness of the glass ceramic substrate, and generally a weight ratio of about 1: 1 is preferable.

The above-mentioned glass ceramic green sheet is formed into a sheet by using a doctor blade or the like after adjusting the glass ceramic powder into a slurry, and its thickness is the thickness of the substrate to be prepared after firing. It may be appropriately set in consideration, and for example, it is molded to about 30 to 200 μm. Further, in order to prepare the above-mentioned slurry, a binder, a plasticizer and a solvent may be added to the glass ceramic powder and mixed by a ball mill, an attritor or the like. As the binder, for example, polyvinyl butyral, methacrylic polymer, acrylic polymer or the like can be used. Further, a phthalic acid derivative or the like can be used as the plasticizer, and alcohols, ketones, chlorine-based organic solvents or the like can be used as the solvent.

The glass-ceramic green sheet prepared as described above is preliminarily charged with the capacitor 2 as described above.
The electrode 21, the dielectric layer 22, the via conductor 3 and a desired wiring pattern not shown in the drawing are formed if necessary. Particularly, in the present invention, between the capacitor electrode 21 and the glass ceramic insulating layer 1. The barrier layer 4 is formed.

As the barrier layer 4, one or more kinds of powder selected from refractory powders of alumina, magnesia, zirconia, titania, and calcia are used as described above, and the powder is kneaded with, for example, a binder. A barrier layer is formed by producing a paste and printing it between the capacitor electrode and the insulating layer. Alternatively, the barrier layer may be formed by sandwiching the green sheet containing the refractory powder described above between the electrode layer and the insulating layer without being limited to the paste as described above.

The particle size of the above refractory powder may be such that it can easily pass through the screen during screen printing, and the average particle size is preferably about 1 to 5 μm. To make the refractory powder into a paste or green sheet, mix 100 parts by weight of the powder with 20 to 30 parts by weight of vehicle,
Mix with a three-roll mill. Although the composition of the vehicle is not particularly limited, for example, ethyl cellulose 4 to 8 wt%
Terpineol solution can be used. When the paste has a viscosity of 200 to 300 Pa · S, it is suitable for printing.

On the other hand, as the dielectric paste for forming the dielectric layer 22 of the capacitor 2, the above-mentioned lead perovskite-based composite material as a main component can be used. These materials may be made into a paste in the same manner as the above refractory powder. Also, the electrode 2 of the capacitor 2
Ag powder or the like may be used as the conductor paste for forming 1 or the via conductor 3 and the wiring pattern, and the powder may be made into a paste in the same manner as described above.

If the thickness of the barrier layer 4 is too thin, the effect of suppressing the diffusion of the glass component is small, and if it is too thick, the surface becomes uneven, so that the thickness is 8 to 20 μm.
A degree is desirable. Further, the thickness of the conductor paste forming the capacitor electrode 21 may be about 7 to 15 μm.
Furthermore, the thickness of the dielectric paste forming the dielectric layer 22 is short if it is too thin, and if it is too thick, the surface becomes uneven, so about 30 to 40 μm is desirable.

Next, the capacitor 2 is preliminarily set as described above.
After laminating a plurality of glass-ceramic green sheets on which the barrier layer 4, the via conductor 3, the wiring pattern, etc. are laminated, they are integrated and fired by a hot press machine or the like. The pressure applied by the hot press machine at that time is, for example, 50 to 300.
The temperature is set to about 60 to 90 ° C. in kg / cm ² . Further, the firing is performed at a temperature of, for example, 1100 ° C. or lower, for example, 80 ° C.
It may be carried out at 0 to 1000 ° C.

[0020]

EXAMPLES Specific examples of the glass ceramic substrate with a built-in capacitor (multilayer wiring substrate) according to the present invention will be described below.

[Examples] In manufacturing a glass-ceramic multilayer wiring board with a built-in capacitor as shown in FIG. 1, as a glass-ceramic powder for forming a glass-ceramic green sheet, a glass powder having the composition shown in Table 1 below ( An average particle size of 2.2 μm) and alumina powder (average particle size of 1.7 μm) were mixed at a ratio of 50:50.

[0022]

9 parts by weight of poly (vinyl butyral) and 7 parts of diisobutyl phthalate per 100 parts by weight of the above mixed powder.
By weight, 1 part by weight of oleic acid, 40 parts by weight of isopropyl alcohol and 20 parts by weight of trichloroethane were added and mixed in a ball mill for 24 hours to prepare a slurry. The slurry was formed into a sheet by the doctor blade method to prepare a glass ceramic green sheet. The thickness of the glass ceramic green sheet was 232 μm.

On the other hand, as the refractory powder for forming the barrier layer 4, alumina having an average particle size of 0.8 μm (AKP-15 manufactured by Sumitomo Chemical Co., Ltd.), magnesia having an average particle size of 1.2 μm, and an average particle size of 0. 9 μm zirconia, average particle size 1.5
Titania having a particle size of 1.3 μm and calcia having an average particle size of 1.3 μm were used alone, and each was kneaded with a terpineol solution containing 6 wt% of ethyl cellulose in a three roll mill,
A variety of refractory pastes were made.

As the conductor paste for forming the electrodes 21 of the capacitor 2, granular Ag having an average particle size of 2 μm is used.
A powder obtained by kneading 100 parts by weight of powder with 20 parts by weight of a terpineol solution containing 8 wt% of ethyl cellulose in a three-roll mill was used. Furthermore, the dielectric layer 2 of the capacitor 2
As the dielectric paste for forming No. 2, Pb (Mg _1/3 Nb _2/3 ) O ₃ powder 100 having an average particle size of 0.3 μm is used.
One part by weight was kneaded with 30 parts by weight of a terpineol solution containing 8% by weight of ethyl cellulose in a three-roll mill and used.

The refractory paste, the conductor paste, and the dielectric paste described above were each formed into a desired thickness by printing or the like to form the barrier layer 4 and the electrode 21 of the capacitor 2 and the dielectric layer 22. The barrier layer 4 was made of different materials for each substrate by using the above five types of refractory paste. The thickness of the barrier layer 4 and the capacitor electrode 21 was 10 μm, and the thickness of the dielectric layer 22 was 30 μm.

Further, the via conductor 4 was formed by filling a 100 μm diameter through hole formed in a glass ceramic green sheet with a conductor paste. As the conductor paste, 100 parts by weight of Ag powder having an average particle size of 10 μm was mixed with 11 parts by weight of a terpineol solution containing 5% ethyl cellulose in a three-roll mill.

As described above, a plurality of glass ceramic green sheets having the capacitors 2 and the via conductors 3 each having the barrier layer 4 made of a different material for each substrate are laminated on each other, and the laminated body is 150 kg / cm ² , 85. Pressure molding was performed under the condition of ° C. Next, after holding at 500 ° C. for 3 hours to remove the binder, firing was performed in air at 875 ° C. for 20 minutes to produce five types of glass ceramic substrates with built-in capacitors of Examples 1 to 5. Then, the dielectric characteristics of the capacitors built in these substrates were examined.

[Comparative Example] As Comparative Example 1 with respect to the above-described Examples, a glass ceramic substrate with a built-in capacitor was prepared in the same manner as above except that the barrier layer was not provided, and the dielectric characteristics of the capacitor built in the substrate were measured. Examined. Further, as Comparative Example 2, the Pb (Mg _1/3 Nb _2/3 ) O ₃ powder used for the dielectric layer 22 of the capacitor 2 in each of the above Examples was pressed into the powder as it is, without being made into a paste, and fired. ,
The dielectric properties of the fired body were examined. The above results are shown in Table 2 below.
Are shown together. The dielectric constant ε and the dielectric loss tan δ in Table 2 are measured values at 1 kHz and room temperature.

[0030]

From the results shown in Table 2 above, when the barrier layer is not used as in Comparative Example 1, the dielectric constant is significantly lowered due to the diffusion of the glass component into the dielectric layer. When the barrier layer is formed as in Examples 1 to 5 according to the present invention, diffusion is suppressed, the dielectric constant is improved to 5000 or more, and good dielectric properties are exhibited.

[0032]

As described above, the glass-ceramic substrate with a built-in capacitor according to the present invention has at least one refractory material selected from alumina, magnesia, zirconia, titania, and calcia between the glass-ceramic insulating layer and the capacitor electrode. By providing the barrier layer containing the powder, it is possible to suppress the diffusion of the insulating material component into the dielectric layer during firing, and it is possible to obtain a capacitor having a high dielectric constant and a low dielectric loss. Moreover, since a layer using a dielectric material as the barrier layer as described above or a refractory powder that is less expensive than forming a metal layer can be used, the cost can be reduced. In addition, the electric resistance value of the electrode can be reduced as compared with the conventional one in which glass powder or the like is added to the electrode layer, and good electric characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a glass ceramic substrate with a built-in capacitor according to the present invention.

[Explanation of symbols]

 1 Insulating Layer 2 Capacitor 21 Capacitor Electrode 22 Dielectric Layer 3 Via Conductor 4 Barrier Layer

Claims (1)

[Claims] 1. In a glass-ceramic substrate with a built-in capacitor obtained by simultaneously firing a glass-ceramic insulating layer, a capacitor electrode, and other circuit wiring, etc., the diffusion of glass components between the capacitor electrode and the glass-ceramic insulating layer is suppressed. A glass ceramic substrate with a built-in capacitor, wherein a barrier layer made of one or more refractory materials selected from alumina, magnesia, zirconia, titania, and calcia is formed.