JP2001163677A - Ceramic green sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic green sheet by which the problems resulting from frictional electrification and peeling electrification generated in a production step can be solved. SOLUTION: In a ceramic green sheet having a circuit pattern on its surface, a water-soluble acrylic binder is incorporated in an amount of 3 to 25 wt.% and the surface resistivity of the surface on which the circuit pattern is formed is controlled to be <=9×1012 (ohms/(square)). Thereby, static electricity generated in a production step can be allowed to easily leak and the formation of a trouble can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic green sheet used for a multilayer ceramic capacitor, a ceramic multilayer substrate and the like.

[0002]

2. Description of the Related Art Conventionally, there is a method called a lamination method as one of methods for manufacturing a multilayer substrate. This method includes the steps of forming a ceramic green sheet, cutting to a predetermined size, forming a conductive hole, filling a conductive paste into the conductive hole, printing a wiring using a screen mask, laminating a predetermined number of sheets, pressing and firing. .

[0003]

In these steps, for example, when a conductive paste is filled or screen printing is performed, the ceramic green sheet is indirectly rubbed with a rubber called a squeegee through a screen mask.
Alternatively, since the film lining the ceramic green sheet is directly rubbed, the ceramic green sheet tends to be triboelectrically charged.

Further, in each step, the finished ceramic green sheets are stored in an overlapping manner, so that peeling charging occurs each time the ceramic green sheets are separated one by one in the next step. The static electricity generated at this time impairs the transportability of the ceramic green sheet and causes a reduction in the equipment operation rate.

Further, in the sheet laminating method, there is a method in which the ceramic green sheet is handled in a state of being backed with a film until immediately before lamination. In this method, when the laminating film and the ceramic green sheet are peeled off at the time of lamination, they are charged by peeling. Since the charging polarity of the already laminated ceramic green sheets and the charging polarity of the peeled ceramic green sheets to be laminated from now on are the same, the ceramic green sheets repel each other and the adhesion is impaired, It may cause lamination displacement.

To solve these problems, there is a method in which an antistatic agent is contained in a slurry for forming a ceramic green sheet. In this case, a large amount of the antistatic agent is added to reduce the surface resistivity. If too long, the slurry gels and the strength of the formed ceramic green sheet decreases.

Accordingly, an object of the present invention is to provide a ceramic green sheet capable of solving the problems caused by frictional charging and peeling charging occurring during the production stage without causing gelation of the slurry or reduction in strength after molding. .

[0008]

According to a first aspect of the present invention, there is provided a ceramic green sheet having a circuit pattern formed on a surface thereof, comprising a water-soluble binder in an amount of 3 to 25% by weight, Provided is a ceramic green sheet characterized in that the surface resistivity of a surface on which a circuit pattern is formed is adjusted to 9 × 10 ¹² (Ω / □) or less.

Generally, the surface resistivity of a dried ceramic green sheet is greater than 1 × 10 ¹³ (Ω / □).
Therefore, at the stage of manufacturing a multilayer ceramic capacitor or a ceramic multilayer substrate, for example, at the time of screen printing, at the time of separating the stacked ceramic green sheets one by one, at the time of peeling of the backing film, etc. Peeling charging occurs. However, in the present invention, the surface resistivity of the ceramic green sheet is 9 × 1
Since it is adjusted to 0 ¹² (Ω / □) or less, the generated charges can be leaked in a short time. Therefore, problems due to frictional charging and peeling charging can be solved.

In the present invention, the ceramic green sheet contains 3 to 25% by weight of a water-soluble binder. Since a water-soluble binder (for example, an acrylic binder) itself has a hygroscopic property, an appropriate amount of water can be maintained by including it in a ceramic green sheet, and the surface resistivity is 9%.
× 10 ¹² (Ω / □) or less. If the content of the water-soluble binder is less than 3% by weight, the strength of the ceramic green sheet is reduced. on the other hand,
If the content exceeds 25% by weight, the sheet molding density is reduced, and in the firing step after laminating and pressing a predetermined number of sheets, there are problems such as difficulty in removing the binder or sintering. When a multilayer substrate, a multilayer capacitor, or the like is manufactured using such a ceramic green sheet, even if peeling charging or friction charging occurs, the generated charge can be leaked in a short time, so that the equipment operation rate decreases and A high-quality multilayer substrate or multilayer capacitor can be manufactured at low cost without causing a lamination shift.

The water-soluble binder is a copolymer of at least one non-reactive monomer selected from the group consisting of carboxylic acid-containing unsaturated monomers and at least one reactive monomer. Preferably, the content of the non-reactive monomer is 0.1 to 50% by weight, and the reactive monomer is acrylic acid or alkyl methacrylate. When the content of the carboxylic acid-containing unsaturated monomer (non-reactive monomer) is less than 0.1% by weight,
In addition to not having the effect of lowering the surface resistivity, the dispersibility of the slurry is significantly reduced, and sheet forming becomes difficult. On the other hand, when the content exceeds 50% by weight, the surface resistivity has an effect of further decreasing, but causes problems such as a decrease in the solid content of the slurry, a prolonged drying time, and a decrease in the molding density.

As in claim 3, the acrylic acid or methacrylic acid alkyl ester in claim 2 is dissolved in water at room temperature and normal pressure in its homopolymer state, and 5 to 90% by weight in the copolymer. If included
Appropriate surface resistivity and quality as a ceramic green sheet can be ensured. If the content of the acrylic acid or alkyl methacrylate is less than 5% by weight, there is no effect of lowering the surface resistance, and if the content exceeds 90% by weight,
Problems such as a decrease in the solid content of the slurry and a decrease in the molding density occur.

In recent years, as a method of forming a circuit pattern on a ceramic green sheet, instead of a screen printing method,
Electrophotography has been proposed. In the transfer step of the electrophotographic method, after charging the ceramic green sheet, the ceramic green sheet is brought into close contact with the photoreceptor, and the obtained chargeable powder image for circuit formation is transferred onto the photoreceptor. After the transfer, the photoreceptor and the ceramic green sheet are separated. At this time, if the surface resistivity of the ceramic green sheet is 1 × 10 ¹³ (Ω / □) or more, peeling discharge occurs at the time of separation, and a remarkable circuit-like shape is formed. The printed figures are disturbed.

[0014] Therefore, a ceramic group according to a fourth aspect is provided.
1 × 10 surface resistivity of lean sheet ⁹ ~ 9 × 10
¹²(Ω / □) is desirable. In other words, surface resistance
9 × 10¹²(Ω / □)
And peeling discharge between the photoreceptor and the ceramic green sheet
Satisfactorily can be transferred without causing the occurrence of However
Then 9 × 10⁸ Below (Ω / □), the charge leaks easily.
The electric field intensity required for transfer cannot be obtained easily, and transfer omission occurs.
1 × 10⁹ (Ω / □) or more
It is.

[0015]

FIG. 1 is a process diagram showing an example of a method for manufacturing a ceramic multilayer wiring board using ceramic green sheets according to the present invention. First, a ceramic slurry is prepared (step S1). In preparing the slurry, a water-soluble binder as described later is contained in an amount of 3 to 25% by weight in addition to the ceramic powder. Next, as shown in FIG.
A sheet is formed thereon to obtain a ceramic green sheet 1 (step S2). As a specific sheet forming method,
There are a doctor blade method, a comma coater method, a reverse roll coater method and the like. The surface resistivity of the obtained ceramic green sheet 1 is such that the water-soluble binder is 3 to 25% by weight.
The content is adjusted to 9 × 10 ¹² (Ω / □) or less. Next, the formed ceramic green sheet 1
Is cut into a predetermined size (step S3). next,
A hole is made in the cut sheet by using mechanical punching, laser punching, or the like (step S
4). Next, the formed conductive holes are filled with a conductive paste using a screen printing method or the like (step S5). Next, a circuit pattern is formed on the ceramic green sheet 1 by using a screen printing method, an electrophotographic method, or the like (Step S6). Next, the ceramic green sheet 1 on which the circuit pattern has been formed is peeled off from the carrier film 2 and laminated (step S7). Next, the laminated ceramic green sheets are pressed (step S8). Finally, the laminated ceramic green sheets are fired to obtain a multilayer substrate (step S9).

In the above process, when the conductive paste is filled in the conductive holes, when the circuit pattern is formed on the ceramic green sheet 1 or when the carrier film 2 is peeled off, the ceramic green sheet is temporarily peeled off. Although charging and frictional charging occur, the ceramic green sheet 1 contains a water-soluble binder in an amount of 3 to 25% by weight, and has a proper amount of moisture due to its hygroscopicity. The surface resistivity of the surface of the green sheet is maintained at 9 × 10 ¹² (Ω / □) or less. Therefore, generated charges can be leaked in a short time, and peeling charging and friction charging can be prevented. As a result, it is possible to solve problems such as a transfer failure, a stack displacement, and a disorder of a circuit pattern.

[0017]

EXAMPLES Example 1 of Claim 2 Table 1 shows the results of sheet formability inspection using ceramic green sheets having the following components. Acrylic acid: Non-reactive monomer selected from carboxylic acid unsaturated monomer group 2-Hydroxyethyl acrylate: Reactive monomer Methyl acrylate: Reactive monomer Ceramic green sheet: Ba-Si-Al-O-based ceramic 90 wt%, water-soluble Ceramic green sheet consisting of 10 wt% binder

[0018]

[Table 1] However, the content of each component is% by weight, and the surface resistivity is Ω / □. As is clear from the above examples, when the content of the non-reactive monomer selected from the carboxylic acid unsaturated monomer group is 0.1 to 50% by weight, the sheet formability is improved.

[Embodiment 2 of Claim 3] Table 1 shows the results of examination of sheet formability using ceramic green sheets having the following components. Acrylic acid: Non-reactive monomer selected from carboxylic acid unsaturated monomer group Ethoxydiethylene glycol acrylate: Reactive monomer soluble in water at normal temperature and normal pressure Methyl acrylate: Reactive monomer not soluble in water at normal temperature and normal pressure Ceramic green sheet: Ceramic green sheet made of Ba-Si-Al-O ceramic 75 wt% and water-soluble binder 25 wt%

[0020]

[Table 2]However, the content of each component is% by weight, and the surface resistivity is Ω / □.
is there. As is clear from Table 2, dissolve in water at normal temperature and normal pressure
If the reactive monomer content is 3% by weight,
The surface resistivity is 5 × 10
¹²Ω / □, the effect of adding the reactive monomer was recognized.
I can't. Therefore, the reactivity to dissolve in water at normal temperature and normal pressure
It is desirable that the monomer content be 5 to 90% by weight.
No.

EXAMPLE 3 Table 3 shows the results of measurement of triboelectric charging, exfoliation charging and exfoliation discharge at the transfer portion in electrophotography using ceramic green sheets made of the components shown in Table 1. Show. However, the thickness of the ceramic green sheet is 15 μm, and a 25 μm thick PET film (surface resistivity 3 × 10 ¹³ Ω) is used as a carrier film.
//) was used. Frictional charge measurement method: Measured after friction between samples for 10 seconds Peeling charge measurement method: Separated ceramic green sheet and carrier film and measured after 5 seconds Charge measuring instrument: Current collecting electrostatic meter Peeling at electrophotographic transfer unit Discharge: Yes → ×, No → ○ Omission at electrophotographic transfer unit: Yes → ×, No → ○

[0022]

[Table 3] As is clear from Table 3, the surface resistivity is 2 × 10 ⁹ to 8
Within the range of × 10 ¹² Ω / □, no problem due to frictional charging or peeling charging occurred.

[Embodiment 4 of Claim 3] Table 4 shows the results of measurement of triboelectric charging, exfoliation charging and exfoliation discharge at the transfer portion in electrophotography using ceramic green sheets made of the components shown in Table 2. Show. The respective charging measurement methods and measuring instruments are the same as in Table 3. However, the thickness of the ceramic green sheet was 17 μm, and a 25 μm-thick PET film (surface resistivity 3 × 10 ¹³ Ω / □) was used as a carrier film.

[0024]

[Table 4] As is clear from Table 4, the surface resistivity was 8 × 10 ^{9 to} 9
It can be seen that in the range of × 10 ¹¹ Ω / □, no problem due to frictional charging or peeling charging occurs.

In the above-described embodiment, an example in which the surface resistance of the ceramic green sheet is reduced without using an antistatic agent has been described. An antistatic agent may be added to the slurry.

[0026]

As is apparent from the above description, according to the present invention, in the stage of manufacturing a multilayer substrate or a multilayer capacitor, a frictional charge or a peeling charge may temporarily occur on a ceramic green sheet. The surface resistivity of the ceramic green sheet is reduced to 9 by adding a conductive binder.
Since the charge is reduced to × 10 ¹² (Ω / □) or less, the generated charges can be leaked in a short time. For this reason, a multilayer substrate can be manufactured without causing a transfer failure, a lamination shift, a circuit disorder, or the like. Further, in the present invention, the water-soluble binder is contained in an amount of 3 to 25% by weight, so that the binder removal processing in the firing step can be easily performed without impairing the moldability, and a high-quality multilayer substrate or laminated board can be obtained. A capacitor can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a manufacturing process of a multilayer substrate.

FIG. 2 is a sectional view of an example of a ceramic green sheet according to the present invention.

Claims (4)

[Claims] 1. A ceramic green sheet having a circuit pattern formed on its surface, wherein a water-soluble binder is used in an amount of 3 to 25.
A ceramic green sheet, wherein the ceramic green sheet is contained by weight and the surface resistivity of a surface on which a circuit pattern is formed is adjusted to 9 × 10 ¹² (Ω / □) or less. 2. The water-soluble binder is a copolymer of at least one non-reactive monomer selected from a carboxylic acid-containing unsaturated monomer group and at least one reactive monomer. The content of the reactive monomer to 0.
2. The ceramic green sheet according to claim 1, wherein the content is 1 to 50% by weight, and the reactive monomer is an acrylic acid or an alkyl methacrylate. 3. 3. The acrylic acid or methacrylic acid alkyl ester, in its homopolymer state, is dissolved in water at normal temperature and normal pressure, and is contained in the copolymer in an amount of 5 to 90% by weight.
The ceramic green sheet according to claim 2, wherein the ceramic green sheet is contained. 4. The ceramic according to claim 1, wherein the surface resistivity of the ceramic green sheet is adjusted to 1 × 10 ^{9 to} 9 × 10 ¹² (Ω / □). Green sheet.