JP2000286143A - Manufacture of ceramic capacitor and paint used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent crawling, peeling, dissolution and permeation in an internal electrode by adding water soluble cellulose dielectric to a dielectric sheet paint. SOLUTION: In a laminated type ceramic capacitor 1, an internal electrode layer 11 and a dielectric layer 12 are laminated alternately, and it has a pair of external electrodes 13 connected to each internal electrode layer 11. The dielectric layer 12 composed mainly of titanate and zirconate is formed of a dielectric sheet paint. Hydroxyethyl cellulose, which is a water-soluble cellulose dielectric, is added to the dielectric sheet paint. The added amount of hydroxyethyl cellulose is set at about 1 to 20 pts.wt. with respect to polyvinyl alcohol which is main binder. The internal electrode layer 11 rare metal, such as platinum, gold, silver or palladium and base metal such as nickel. Thereby, even if dielectric sheet paint is made water soluble, nonconformities such as crawling, peeling, dissolution and permeation in the internal electrode can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing various ceramic capacitors such as a multilayer ceramic capacitor and a paint used for the same, and more particularly, to a ceramic sheet in which a dielectric sheet paint constituting a green sheet is composed of a water-soluble paint. The present invention relates to a method for manufacturing a ceramic capacitor suitably used for a capacitor and a paint used for the method.

[0002]

2. Description of the Related Art In this type of multilayer ceramic capacitor, first, a dielectric sheet paint composed of a dielectric powder, a binder, a plasticizer and an organic solvent is applied on an organic film by a doctor blade method, and has a thickness of several tens. A green sheet is prepared by molding a ceramic dielectric of μm. On this green sheet, an internal electrode paint is printed by a printing method to form an internal electrode layer, a plurality of green sheets on which the internal electrode layer is printed are stacked, and then thermocompression bonded to form a laminated molded body. I do. Then, this is cut into chips and fired, and then external electrodes are formed to obtain a multilayer ceramic capacitor.

[0003] In such a conventional multilayer ceramic capacitor, an organic solvent-based coating is used as a dielectric sheet coating constituting the green sheet (referred to as a slurry comprising the above-mentioned dielectric powder, binder, plasticizer and organic solvent). Therefore, not only the problem of the cost of the organic solvent but also the problem of the release of the organic solvent to the atmosphere due to drying and exhaustion, that is, the problem of air pollution and global warming, or the problem of the cost of a solvent recovery device have been pointed out. Therefore, changing the dielectric sheet paint to a water-soluble paint has been studied.

[0004]

The internal electrode paint formed on a green sheet by a printing method has a problem in that a screen used in a printing process has durability against a water-soluble paint, more specifically, a water resistance of a screen masking resin. It is said that it is desirable to use an organic solvent such as butyl carbitol and terpineol because of poor properties. For this reason, if the dielectric sheet paint is composed of a water-soluble paint, the compatibility between these dielectric sheet paints and the internal electrode paint deteriorates, causing problems such as repelling the internal electrode paint and peeling off the internal electrode layer. Was.

[0005] Further, when the water resistance of the screen in the printing process is eliminated and the internal electrode paint is also composed of a water-soluble paint, the internal electrode paint dissolves the green sheet or permeates the green sheet, so that the capacitor is removed. However, there has been a problem that the electrostatic capacity of the capacitor is reduced or varies, or the reliability of the electrical characteristics of the capacitor is reduced.

The present invention has been made in view of such problems of the prior art, and a ceramic capacitor which can prevent repelling, peeling, dissolution, and penetration of internal electrodes even when a dielectric sheet coating is made water-soluble. And a paint used for the method.

[0007]

(1) In order to achieve the above object, a method of manufacturing a ceramic capacitor according to a first aspect of the present invention comprises forming a dielectric layer with a dielectric sheet paint, A method for manufacturing a ceramic capacitor in which an internal electrode layer is formed on a main surface of a layer by an internal electrode coating, wherein the dielectric sheet coating contains a water-soluble cellulose derivative.

Considering the durability of the screen in the printing process, it is desirable to use an organic solvent-based paint as the internal electrode paint. The main solvent is butyl carbitol and the like, and the binder is a non-aqueous cellulose derivative such as ethyl cellulose. Used. Therefore, when the water-soluble cellulose derivative is contained in the dielectric sheet coating, the compatibility between the water-soluble cellulose derivative and the cellulosic binder of the internal electrode coating is improved even when the water-soluble cellulose derivative is made into a water-soluble coating, whereby the internal Problems such as repelling and delamination of the electrode paint can be prevented.

In the above invention, the water-soluble cellulose derivative is preferably in the same system as the binder of the internal electrode paint, and is not particularly limited, but is more preferably hydroxyethyl cellulose (HEC).

In particular, when the water-soluble cellulose derivative is hydroxyethyl cellulose, its content is preferably in the range of 1 to 20 parts by weight with respect to the main binder such as polyvinyl alcohol. If the amount is less than this, repelling of printed electrodes becomes a problem, and if it is more than this, separation of the main binder and hydroxyethyl cellulose becomes a problem.

In the above invention, although not particularly limited, at least one of the dielectric sheet paint and the internal electrode paint may contain an amine organic solvent.

In an amine organic solvent containing an amino group, the OH group of the amino group shows hydrophilicity, while the CH group of the amino group shows hydrophobicity. By including in at least one of the sheet paint and the internal electrode paint, the compatibility and incompatibility of the dielectric layer and the internal electrode layer are improved, and the internal electrode paint repelling, delamination, and dielectric sheet Disadvantages such as dissolution and interlayer penetration can be further prevented.

In this case, the amine-based organic solvent may be contained in at least one of the dielectric sheet paint and the internal electrode paint. That is, when contained only in the dielectric sheet paint, when contained in the internal electrode paint,
In addition, it is intended to include all cases where it is contained in both the dielectric sheet paint and the internal electrode paint.

As described above, the amine-based organic solvent is not particularly limited as long as it is an organic solvent having an amino group, and is preferably triethanolamine (TEA).

In particular, when the amine-based organic solvent is triethanolamine and is contained in the dielectric sheet paint, the content is 1 to 80 with respect to the binder.
It is preferred to be in the range of parts by weight. If the amount is less than this, repelling of printed electrodes becomes a problem, and if it is more than this, penetration of the internal electrode layer into the sheet becomes a problem.

In the case where the amine-based organic solvent is triethanolamine, and when it is contained in the internal electrode paint, the content is 0.5 to the conductive powder (metal).
It is preferably in the range of 5 to 5 parts by weight. If the amount is less than this, repelling of printed electrodes becomes a problem, and if it is more than this, penetration of the internal electrode layer into the sheet becomes a problem.

[0017] Other components of the dielectric sheet coating and the internal electrode coating containing the amine-based organic solvent may include a binder, a dispersant, a plasticizer, and the like.

In particular, when the dielectric sheet paint is composed of a water-soluble paint, examples of the binder include polyvinyl alcohol, polyvinyl acetal, cellulose, water-soluble acrylic resin, and emulsion.
Among them, polyvinyl alcohol is more preferable. By using a polyvinyl alcohol binder,
This is because there is an effect that sufficient strength can be obtained when the dielectric layer is made thin.

Incidentally, when the dielectric sheet paint contains triethanolamine, the triethanolamine functions as a modifier for the compatibility / incompatibility between the dielectric layer and the internal electrode layer. In addition to exerting its function, it also has a function as a plasticizer. Therefore, the content of triethanolamine referred to in the present invention is a total amount including that contained as a plasticizer. In addition, when adding only as a compatibility / incompatibility adjuster of the dielectric layer and the internal electrode layer, a binder (polyvinyl alcohol, hereinafter referred to as PV)
Abbreviated as A. ) Is preferably in the range of 1 to 20 parts by weight.

(2) In order to achieve the above object, a ceramic capacitor paint according to the present invention according to a second aspect is a dielectric sheet paint constituting a dielectric layer of a ceramic capacitor, comprising a water-soluble cellulose derivative. It is characterized by containing.

As described above, it is considered desirable that the internal electrode paint be an organic solvent-based paint in consideration of the durability of the screen in the printing process, and butyl carbitol, terpineol or the like is used as a main solvent, and the binder is used as a binder. Non-aqueous cellulose derivatives such as ethyl cellulose are used.
Therefore, if the water-soluble cellulose derivative is contained in the dielectric sheet coating, the compatibility between the water-soluble cellulose derivative and the non-aqueous cellulose derivative binder of the internal electrode coating is improved even when the water-soluble cellulose derivative is formed into a water-soluble coating. In addition, problems such as repelling and delamination of the internal electrode paint can be prevented.

In the above invention, the water-soluble cellulose derivative is preferably in the same system as the binder of the internal electrode coating material, and is not particularly limited, but is more preferably hydroxyethyl cellulose (HEC).

In particular, when the water-soluble cellulose derivative is hydroxyethyl cellulose, its content is preferably in the range of 1 to 20 parts by weight with respect to the main binder such as polyvinyl alcohol. If the amount is less than this, repelling of printed electrodes becomes a problem, and if it is more than this, separation of the main binder (PVA) and hydroxyethyl cellulose becomes a problem.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. Structure Figure 1 of the multilayer ceramic capacitor is a partially broken perspective view showing an embodiment of a capacitor of the present invention, the multilayer ceramic capacitor 1, the internal electrode layer 11 and the dielectric layer 12 are alternately laminated, It has a pair of external electrodes 13 connected to each internal electrode layer 11.

As the internal electrode layer 11, platinum Pt, gold A
u, silver Ag, palladium Pd, a noble metal such as a palladium alloy, or a base metal such as nickel or a nickel alloy. Various conditions such as the thickness of the internal electrode 11 may be appropriately determined according to the purpose and use, but the thickness is usually 1 to 3 μm, particularly 1 to 2 μm.

The material of the dielectric layer 12 is not particularly limited, and is generally a titanate (for example, BaTiO ₃ , Sr
TiO ₃ ), zirconate (eg, BaZr)
O _3, PbZrO ₃₎ the main component, oxides as additives, chlorides, in which the nitrate and the like were included.

The external electrode 13 is usually made of copper, a copper alloy, nickel, a nickel alloy, or the like, but silver or an alloy of silver and palladium can also be used. The thickness of the external electrode 13 is arbitrary and may be appropriately determined depending on the purpose and application, but is usually 10 to 50 μm.

The shape and size of such a multilayer ceramic capacitor 1 may be appropriately determined according to the purpose and application. For example, in the case of a rectangular parallelepiped, usually 1.6 to
3.2mm × 0.8-1.6mm × 0.6-1.2mm
It is about.

The manufacturing method Figure 2 of the multilayer ceramic capacitor is a process diagram for explaining an embodiment of a method for manufacturing a ceramic capacitor of the present invention, the multilayer ceramic capacitor 1 of the present embodiment is as follows manufacturing can do.

In this embodiment, first, a dielectric sheet paint (also referred to as a dielectric layer paste), an internal electrode paint (also referred to as an internal electrode paste), and an external electrode paint (also referred to as an external electrode paste). Manufacture each.

The dielectric sheet paint is prepared by kneading a dielectric material and water according to the composition of the above-described dielectric composition to obtain a water-soluble paint, or kneading the dielectric material and an organic vehicle to form an organic material. Although it can be obtained by using a solvent-based coating, it is more preferable to manufacture it as a water-soluble coating from the viewpoint of reducing the cost of the ceramic capacitor, releasing the organic solvent to the atmosphere by dry exhaust, and the cost of an organic solvent recovery device.
In this example, a water-soluble paint is used.

The dielectric material may be appropriately selected from the aforementioned composite oxides and various compounds that become oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like, and may be used in combination. . The content of each compound in the dielectric material may be determined so as to have the above-described composition of the dielectric layer after firing. The dielectric material usually has an average particle diameter of 0.1 to
Used as a powder of about 3.0 μm.

The water-soluble paint is obtained by dissolving a water-soluble binder, a dispersant, and the like in water. The water-soluble binder is not particularly limited, and polyvinyl alcohol, polyvinyl acetal, cellulose, water-soluble acrylic resin, It can be appropriately selected from emulsions and the like. Above all, it is preferable to use polyvinyl alcohol as the water-soluble binder because sufficient strength can be obtained when the dielectric layer is made thin. In this case, the addition amount of polyvinyl alcohol is preferably 4 to 20 parts by weight.
If it is less than this, the strength of the sheet is insufficient (insufficient shape retention), and if it is more than this, shrinkage during firing is large,
This is because sinterability is further deteriorated.

In particular, in this example, a water-soluble cellulose derivative, hydroxyethyl cellulose, is added to the dielectric sheet paint. This hydroxyethyl cellulose is
It is preferable to add 1 to 20 parts by weight to the main binder (PVA). If the amount is less than this, the strength of the printed electrode becomes a problem, and if it is more than this, separation of the main binder and hydroxyethyl cellulose becomes a problem.

The internal electrode paint is prepared by kneading the above-mentioned organic vehicle with the above-mentioned various conductive metals or alloys or the above-mentioned various conductive oxides, organometallic compounds, resinates and the like after firing. Is done. The external electrode paint is also prepared in the same manner as the internal electrode paint.

When the sheet method is used, a green sheet is formed by using a dielectric sheet paint, an internal electrode paint is printed thereon, and these are laminated to form a green chip. On the other hand, when the printing method is used, a dielectric sheet paint and an internal electrode paint are laminated and printed on a substrate such as polyethylene terephthalate, cut into a predetermined shape, and then peeled off from the substrate to form a green chip.

When a water-soluble paint is used as the dielectric sheet paint, to obtain such green chips, provisional press at room temperature → humidity control (for example, 25 ° C., 80% RH, 24
Time) → room temperature press → warming press (for example, 40 ° C.). However, humidity control is not always necessary, but by adding hydroxyethylcellulose or triethanolamine and hydroxyethylcellulose as in the present embodiment, the effect of humidity control becomes more remarkable.

Next, the green chip is subjected to binder removal processing and firing. The binder removal process is performed before firing,
What is necessary is just to carry out under normal conditions. The firing atmosphere of the green chip may be appropriately determined according to the type of the conductive material in the internal electrode paint. Further, the binder removal treatment and the firing may be performed continuously or independently of each other.

The fired capacitor body obtained as described above is subjected to edge polishing using, for example, a barrel polisher or a sand blast machine, and an external electrode paint is printed or transferred and baked to form an external electrode layer. Then, if necessary, a coating layer is formed on the surface of the external electrode layer by plating or the like.

The ceramic capacitor 1 of this embodiment manufactured in this manner is mounted on a printed circuit board by soldering or the like, and is used for various electronic devices.

[0041]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. Example 1 First, in order to prepare a dielectric sheet paint, 100 parts by weight of a dielectric raw material powder containing barium titanate having an average particle diameter of 0.1 to 2 μm as a main component, 20 parts by weight of water, and a dispersant Of ammonium polycarboxylate and 0.4 part by weight of a polyhydric alcohol as a wetting agent were mixed by a conventional method in a ball mill for 16 hours to disperse and mix the ceramic powder.

Further, 6 parts by weight of polyvinyl alcohol was added in terms of solid content, and glycerin as a plasticizer was added to 3 parts by weight.
1 part by weight of hydroxyethyl cellulose (HEC) as a water-soluble cellulose derivative according to the present invention is added to a binder (PVA), and the mixture is mixed for 20 minutes by a mixer to perform defoaming, dispersion, and mixing. It turned into a paste.

To prepare an internal electrode coating material, 100 parts by weight of palladium powder having an average particle size of 1 to 5 μm, 97 parts by weight of butyl carbitol as a main solvent, and 8.5 parts by weight of ethyl cellulose as a binder were kneaded. And then turned into a paste.

Next, the above-mentioned dielectric sheet paint is applied on a PET film by a doctor blade method to form a green sheet having a thickness of 30 μm, and the above-mentioned internal electrode paint is printed thereon by a printing method. The green sheet was peeled off from the PET film. Next, the plurality of green sheets thus obtained are laminated, and subjected to pressure bonding such as room temperature temporary press → humidity control (25 ° C., 80% RH, 24 hours) → room temperature press → heated press (40 ° C.). By doing so, a green chip was produced. The number of stacked green sheets having internal electrodes was three.

Next, the green chip was cut into a predetermined size, subjected to a binder removal treatment and fired to obtain a fired multilayer ceramic body.

This binder removal treatment is performed at a temperature rising time of 300 ° C.
/ Hour, holding temperature 600 ° C., holding time 2 hours, and air atmosphere. In addition, firing is performed at a heating rate of 300 ° C /
Time, holding temperature 1340 ° C., holding time 3 hours, cooling rate 300 ° C./hour.

The size of each sample is 3.2 mm × 1.6 m
m × 0.6 mm, the thickness of the dielectric layer was 20 μm, and the thickness of the internal electrode layer was 3.8 μm.

Each sample of the multilayer ceramic capacitor thus obtained was evaluated for stacking property, binder separation property and permeability. The evaluation of the stacking property is an evaluation of whether or not interlayer peeling occurs after cutting before firing, and the number ratio (%) of defective articles to 100 samples was calculated. In addition, evaluation of binder (PVA, HEC) separability
A and HEC were mixed by a mixer, and the mixed state when left for 48 hours was visually evaluated. A sample in which the mixing state was good was marked with "O", and a sample in which separation was observed was marked with "X".

The evaluation of the permeability is an evaluation as to whether or not the internal electrode layer shows off on the green sheet. The case where no show-through is observed for 100 prepared samples is indicated by “○”, However, the case where it was observed was designated as "x". Table 1 shows the results.

Example 2 In Example 1, the amount of hydroxyethylcellulose added to the dielectric sheet paint was set to 20 with respect to the binder.
A sample was prepared and evaluated under the same conditions as in Example 1 except that the weight was used. Table 1 shows the results.

Example 3 In Example 1, 10 parts by weight of polyvinyl alcohol was used.
A sample was prepared and evaluated under the same conditions as in Example 1 except that glycerin was used in an amount of 5 parts by weight. Table 1 shows the results.

Example 4 A sample was prepared and evaluated under the same conditions as in Example 1 except that 0.5 parts by weight of triethanolamine was added to the internal electrode paint. Table 1 shows the results.

Example 5 A sample was prepared and evaluated under the same conditions as in Example 1 except that 1 part by weight of triethanolamine was added to the internal electrode paint. Table 1 shows the results.

Example 6 A sample was prepared and evaluated under the same conditions as in Example 1 except that 5 parts by weight of triethanolamine was added to the internal electrode paint. Table 1 shows the results.

Comparative Example 1 A sample was prepared and evaluated under the same conditions as in Example 1 except that hydroxyethyl cellulose was not added to the dielectric sheet paint. Table 1 shows the results.

Comparative Example 2 In Example 1, the amount of hydroxyethylcellulose added to the dielectric sheet paint was 0.1% with respect to the binder.
A sample was prepared and evaluated under the same conditions as in Example 1 except that the amount was 05 parts by weight. Table 1 shows the results.

COMPARATIVE EXAMPLE 3 In Example 1, the amount of hydroxyethyl cellulose added to the dielectric sheet paint was 0.1% with respect to the binder.
A sample was prepared and evaluated under the same conditions as in Example 1 except that the amount was 5 parts by weight. Table 1 shows the results.

Comparative Example 4 The amount of hydroxyethylcellulose added to the dielectric sheet paint in Example 1 was 30
A sample was prepared and evaluated under the same conditions as in Example 1 except that the weight was used. Table 1 shows the results.

[0059]

[Table 1]

As is clear from the results, the amount of hydroxyethylcellulose added to the dielectric sheet paint was 1%.
When the amount was less than parts by weight (Comparative Examples 1 to 3), particularly when no additive was added (Comparative Example 1), the stacking property was significantly reduced. When the amount of hydroxyethylcellulose was 30 parts by weight (Comparative Example 3), separation of the binder (PVA) and hydroxyethylcellulose occurred.

[0061]

As described above, according to the present invention, even when the dielectric sheet paint is made water-soluble, defects such as repelling, peeling, dissolution, and penetration of the internal electrodes are prevented, and a high-quality ceramic capacitor is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a capacitor of the present invention.

FIG. 2 is a process chart illustrating an embodiment of a method for manufacturing a capacitor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 11 ... Internal electrode layer 12 ... Dielectric layer 13 ... External electrode

Continued on the front page F term (reference) 5E001 AB03 AC09 AE00 AH01 AJ01 5E082 AA01 AB03 BC32 EE04 EE21 EE35 FG06 FG26 FG33 FG54 LL01 MM24 PP03

Claims (8)

[Claims] 1. A method for manufacturing a ceramic capacitor, comprising: forming a dielectric layer by a dielectric sheet paint; and forming an internal electrode layer by an internal electrode paint on a main surface of the dielectric layer. And a water-soluble cellulose derivative. 2. The method according to claim 1, wherein the water-soluble cellulose derivative is hydroxyethyl cellulose. 3. The method for producing a ceramic capacitor according to claim 2, wherein said dielectric sheet paint contains 1 to 20 parts by weight of hydroxyethyl cellulose based on the main binder. 4. The method according to claim 1, wherein at least one of the dielectric sheet paint and the internal electrode paint contains an amine organic solvent. 5. The method according to claim 4, wherein said amine organic solvent is triethanolamine. 6. The dielectric sheet paint according to claim 1, wherein the binder is polyvinyl alcohol.
The method for manufacturing a ceramic capacitor according to any one of the above. 7. A dielectric sheet paint for forming a dielectric layer of a ceramic capacitor, which comprises a water-soluble cellulose derivative. 8. The paint for a ceramic capacitor according to claim 7, wherein said water-soluble cellulose derivative is hydroxyethyl cellulose.