JPH06231992A - Method of manufacturing green body for lamination ceramic capacitor - Google Patents

Abstract

PURPOSE:To make the thickness of an electrode layer forming part after laminated in the same degree as that of part non-forming the electrode layer and not to prevent a debinder of an internal electrode layer at debinding a laminated layer form and not to cause the deterioration in a delamination and a thermal shock level. CONSTITUTION:A dielectric powder and a first organic binder and a first solvent are mixed to regulate a dielectric slurry, and the same powder with the dielectric powder and a second organic binder and a second solvent are mixed to regulate a dielectric paste. A plurality of internal electrode layers 11 are formed at intervals on a dielectric layer 10 formed by the dielectric slurry, and in a part among electrode layers and end parts of the electrode layers on this dielectric layer 10, the dielectric paste is printed and dried to form a thickness regulating dielectric layer 12 in the same degree as the thickness of the electrode layer. On the dielectric layer 12 and electrode layer 11, an overlapping dielectric layer 13 is formed by the dielectric slurry. The first solvent does not have any compatibility with the second organic binder and the second solvent not with the first organic binder, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a green body for a monolithic ceramic capacitor which can be applied to a wet laminating method or a dry laminating method.

[0002]

2. Description of the Related Art In recent years, with miniaturization of radios, microcassette recorders, electronic tuners, video cameras, etc., and development of thin and lightweight electronic equipment, there has been a strong demand for miniaturization and large capacity of capacitors used as circuit elements. It started to come. A monolithic ceramic capacitor is known as a component that satisfies these requirements. To manufacture this monolithic ceramic capacitor, first, for example, dielectric powder,
A dielectric ceramic slurry containing an organic binder, a plasticizer, and an organic solvent is used to prepare a ceramic dielectric green sheet having a thickness of tens of μm on an organic film by a doctor blade method. Then, a conductive paste is screen-printed and dried on the sheet at intervals to form a plurality of internal electrode layers. Next, after stacking a plurality of green sheets on which internal electrode layers have been formed and producing a laminated molded body by pressure bonding, cutting and firing into a chip shape in units of the laminated internal electrode layers, and finally externally attaching to both ends of the chip body. Form electrodes.

On the other hand, demands for miniaturization and large capacity of capacitors have been further strengthened recently, and in order to meet these demands, it is indispensable to increase the number of laminated layers and thin dielectric layers. However, when a large-capacity monolithic ceramic capacitor is manufactured by the above method, if the number of laminated layers increases, the portion where the electrode layer 1 is formed due to the thickness of the electrode layers after lamination as shown in FIG. The thickness a of 2 is larger than the thickness b of the portion 3 where the electrode layer 1 is not formed. In this state, if the layers are laminated by thermocompression bonding, the pressure in the portion 3 where the electrode layer is not formed becomes insufficient due to the difference between the thickness a of the portion 2 where the electrode layer is formed and the thickness b of the portion 3 where the electrode layer is not formed. Become. Therefore, there is a problem that the adhesion between the layers is poor, and a peeling phenomenon between the electrode layer and the dielectric layer, that is, so-called delamination is likely to occur during firing.

In order to solve this problem, as shown in FIG. 2, a plurality of internal electrode layers 21 are formed by printing and drying a conductive paste on the base film 20 at intervals, and the electrodes on the base film 20 are formed. After the dielectric paste is printed and dried between the layers 21 and on the end portion of the electrode layer 21 to form the thickness adjusting dielectric layer 22 having the same thickness as the electrode layer, the thickness adjusting dielectric layer 22 and the internal electrode. There has been proposed a method for manufacturing a green sheet for a laminated ceramic capacitor in which a superposing dielectric layer 23 made of a dielectric slurry is formed on the layer 21 (JP-A-3-74820). In the case of the above manufacturing method, the printing pattern of the conductive paste and the printing pattern of the dielectric paste have a negative and positive relationship with the photographic film.

[0005]

However, Japanese Patent Laid-Open No. 3-7
In the method disclosed in Japanese Patent No. 4820, since the dielectric slurry and the dielectric paste have the same composition, in other words, the organic binder and the solvent contained in the dielectric slurry and the organic binder and the solvent contained in the dielectric paste are different from each other. Since they are the same and compatible with each other, the solvent of the dielectric slurry dissolves part of the binder of the dielectric paste in the stacked state, and the solvent of the dielectric paste also easily dissolves part of the binder of the dielectric slurry. . As a result, the degree of adhesion between the thickness adjusting dielectric layer 22 and the stacking dielectric layer 23 is increased, and the binder of the conductive paste on which the internal electrode layers are formed is less likely to be removed when the binder is removed from the laminate. If the binder removal from the internal electrode layers is blocked, the bubbles generated during binder removal will remain inside the capacitor as they are after firing the laminated molded body, causing delamination, cracks, etc., or immersing the capacitor in the solder bath without preheating. A new problem occurs such as deterioration when a thermal shock of a certain degree is given.

The object of the present invention is to make the thickness of the portion where the electrode layer is formed after lamination approximately the same as the thickness of the portion where the electrode layer is not formed, so that the internal electrode layer is removed when the binder is removed from the laminated molded body. Another object of the present invention is to provide a method for manufacturing a green body for a laminated ceramic capacitor, which does not hinder the removal of the binder and does not cause delamination or deterioration at the thermal shock level.

[0007]

According to the manufacturing method of the present invention, first, a dielectric powder, a first organic binder and a first solvent are kneaded to prepare a dielectric slurry, and the same powder as the dielectric powder and 2 An organic binder and a second solvent are kneaded to prepare a dielectric paste. Next, as shown in FIG. 1, a conductive paste is printed and dried on the dielectric layer 10 formed of the dielectric slurry at intervals to form a plurality of internal electrode layers 11 to form the internal electrode layers 11. The above-mentioned dielectric paste is printed and dried between the electrode layers 11 on the dielectric layer 10 and on the end portions of the electrode layer 11 to form a thickness adjusting dielectric layer 12 having the same thickness as the electrode layer 11. Then, the stacking dielectric layer 13 made of the above-mentioned dielectric slurry is formed on the thickness adjusting dielectric layer 12 and the internal electrode layer 11.

As another manufacturing method, after preparing the above-mentioned dielectric slurry and dielectric paste, a conductive paste is printed and dried on the base film 20 at intervals as shown in FIG. 2 to form a plurality of internal electrode layers. 21 is formed, and the above-mentioned dielectric paste is printed and dried between the electrode layers 21 on the base film 20 and at the end portions of the electrode layers 21 to form a thickness adjusting dielectric layer 22 having a thickness similar to that of the electrode layers 21. To do. Then, a stacking dielectric layer 23 made of the above dielectric slurry is formed on the thickness adjusting dielectric layer 22 and the internal electrode layer 21. The characteristic constitution of the present invention is that the first solvent is incompatible with the second organic binder and the second solvent is incompatible with the first organic binder. Note that each layer in FIG. 1 is shown in a reduced scale compared to FIG. 2 in order to facilitate understanding of the laminated green body 17 in FIG.

The green body 27 shown in FIG. 2 (d) is
The laminated green body 28 is crimped by the hot press shown in FIG. That is, the hot platen 31 of the hot press machine is overlaid and pressed on the laminated green body 28 on the press table 32 from the back side of the base film 20 to transfer the dielectric layers 23, 22 and the electrode layer 21.

A specific combination of the first organic binder, the first solvent, the second organic binder and the second solvent is, for example, the first organic binder.
When the organic binder is either polyvinyl alcohol or polyvinyl butyral and the first solvent is a lower alcohol, the second organic binder is a cellulosic resin and the second solvent is a high chain saturated hydrocarbon. Also, the opposite combination may be used. That is, when the second organic binder is either polyvinyl alcohol or polyvinyl butyral and the second solvent is a lower alcohol, the first organic binder is a cellulosic resin,
The first solvent is a high chain saturated hydrocarbon. When an acrylic resin is used as the organic binder of the dielectric slurry or the dielectric paste, polyvinyl butyral or a cellulosic resin that is incompatible with the solvent that dissolves the resin is used as the organic material of the dielectric paste or the dielectric slurry. It can also be used as a binder. Here, hydrocarbons having 2 to 6 carbons are exemplified as the lower alcohol, and hydrocarbons having 8 to 12 carbons (octane, nonane, decane, undecane and dodecane) are exemplified as the high chain saturated hydrocarbon.

[0011]

The second solvent of the dielectric paste contained in the dielectric layers 12 and 22 for adjusting the thickness formed on the dielectric layer 10 or the base film 20 is filled with the dielectric layers 13 and 23 or the dielectric layer 20 for superposition. Since a part of the first organic binder contained in is not dissolved, the first solvent also contained in the stacking dielectric layers 13 and 23 or the dielectric layer 20 is contained in the thickness adjusting dielectric layers 12 and 22. Since a part of the 2 organic binder is not dissolved, some gaps are formed between the stacking dielectric layers 13 and 23 or the dielectric layer 20 and the thickness adjusting dielectric layers 12 and 22. As a result, the binder does not interfere with the removal of the internal electrode layers 11 and 21 at the time of removing the binder from the multilayer molded body, so that no bubbles remain inside the multilayer ceramic capacitor.

[0012]

EXAMPLES Next, examples of the present invention will be described together with comparative examples. The invention is not limited to this example. <Example> After mixing 10 parts by weight of polyvinyl butyral resin with 100 parts by weight of relaxor-based dielectric powder, 50 parts by weight of butanol was added as a solvent and kneaded with a ball mill to prepare a dielectric slurry. This dielectric slurry is used for the lower cover dielectric layer 10 shown in FIG.
It is used to form the stacking dielectric layer 13 and the upper cover dielectric layer 14. On the other hand, after adding 12 parts by weight of ethyl cellulose resin to 100 parts by weight of the same relaxor-based dielectric powder as the above powder, the solvent has 12 carbon atoms.
60 parts by weight of dodecane was added and kneaded in the same manner to prepare a dielectric paste. This dielectric paste is shown in Figure 1 (c).
Used to form the thickness adjusting dielectric layer 12 shown in the enlarged view of FIG.

Next, the dielectric slurry was printed on the base plate 16 and dried. This dielectric slurry was repeatedly printed and dried to a predetermined thickness to form a lower cover dielectric layer 10 as shown in FIG. 1 (a). Next, a commercially available conductive paste containing Ag is screen-printed on the dielectric layers 10 stacked in a positive pattern.
After drying, a plurality of internal electrode layers 11 were formed at intervals. Subsequently, as shown in FIG. 1B, the dielectric paste is screen-printed between the electrode layers 11 and at the end portions of the electrode layers 11 in a negative pattern corresponding to the positive pattern, so that the dielectric paste is almost the same as the electrode layer 11. The thickness adjusting dielectric layer 12 was formed to have the same thickness. As shown in FIG. 1C, the dielectric slurry was printed and dried on the dielectric layer 12 and the electrode layer 11 to form a superposing dielectric layer 13. As shown in FIG. 1D, the electrode layer 11 and the dielectric layer 12 are formed.
Then, the dielectric layer 13 was repeatedly formed, and then the above dielectric slurry was repeatedly printed and dried to a predetermined thickness to form the upper cover dielectric layer 14. Thus, a green body 17 for laminated ceramic capacitor was obtained. This green body is cut into chips, and the chip body is baked,
External electrodes were formed on both ends of the chip body to produce a chip type multilayer ceramic capacitor.

<Comparative Example> A chip type multilayer ceramic capacitor was manufactured in the same manner as in the example except that the organic binder and solvent of the dielectric paste were the same as those of the above dielectric slurry.

<Thermal Shock Test> The chip capacitors of Examples and Comparative Examples were evaluated by a thermal shock test. That is, grab each chip capacitor with tweezers one by one, and heat the chip end at 350 ° C without preheating it.
Of Sn60 / Pb40 eutectic solder bath for 1 second and then pulled up. Boil this sample in concentrated nitric acid for 20 minutes,
The external electrode was dissolved. 100 chip capacitors of each of the example and the comparative example were tested, and it was examined whether or not cracks were generated in the chip body of the external electrode traces. As a result, the chip capacitor of the comparative example had 83 cracks, whereas the chip capacitor of the example had no cracks at all.

In the above example, the green body was manufactured by the wet laminating method, but the manufacturing method of the present invention is not limited to the above example and can be applied to the dry laminating method.

[0017]

As described above, the solvent of the dielectric paste used to form the thickness adjusting dielectric layer of the present invention is used to form the upper and lower cover dielectric layers and the stacking dielectric layer. Because it does not dissolve part of the organic binder of the dielectric slurry, and because the solvent of this dielectric slurry does not dissolve part of the organic binder of the dielectric paste,
A slight gap is generated between the stacking dielectric layer and the thickness adjusting dielectric layer, and the binder removal of the internal electrode layers is not obstructed during binder removal. Therefore, since the laminated ceramic capacitor can be obtained by firing without leaving any bubbles inside the green body after the binder is removed, the deterioration of the thermal shock level can be improved. Further, the unevenness between the electrode layer forming portion and the portion where the electrode is not formed in the laminated molded body is eliminated, and a laminated ceramic capacitor having a good internal structure and excellent reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating the production of a green body by the wet lamination method of the present invention.

FIG. 2 is a cross-sectional view illustrating the production of a green body by the dry laminating method of the present invention.

FIG. 3 is a cross-sectional view showing a state in which a green body produced by the dry laminating method is hot pressed onto the laminated green body.

FIG. 4 is a cross-sectional view of a conventional laminated green body.

[Explanation of symbols]

 10 Dielectric Layer for Lower Cover 11 Internal Electrode Layer 12 Dielectric Layer for Adjusting Thickness 13 Dielectric Layer for Overlay 14 Dielectric Layer for Upper Cover 20 Base Film 21 Internal Electrode Layer 22 Dielectric Layer for Adjusting Thickness 23 Dielectric for Overlay layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Takada 2270 Yokose, Yokose-cho, Chichibu-gun, Saitama Sanryo Materials Co., Ltd.

Claims (4)

[Claims] 1. A step of preparing a dielectric slurry by kneading a dielectric powder, a first organic binder and a first solvent; a powder the same as the dielectric powder; a second organic binder; and a second organic binder.
A step of preparing a dielectric paste by kneading a solvent, a plurality of conductive paste is printed and dried at intervals on the dielectric layer (10) or the base film (20) formed by the dielectric slurry. A step of forming the internal electrode layers (11, 21), between the electrode layers (11, 21) on the dielectric layer (10) or the base film (20) on which the internal electrode layers are formed, and between the electrode layers (11,2
The dielectric paste is printed and dried at the end of 1) and the thickness is adjusted to the same level as the thickness of the electrode layers (11, 21).
And a step of forming a thickness adjusting dielectric layer (12,22) and internal electrode layers (11,21)
On top of the dielectric layer (13,2
3) The method for manufacturing a green body for a laminated ceramic capacitor, which comprises the step of forming), wherein the first solvent is incompatible with the second organic binder and the second solvent is incompatible with the first organic binder. A method of manufacturing a green body for a laminated ceramic capacitor, which is characterized. 2. The first organic binder is either polyvinyl alcohol or polyvinyl butyral, and
The method for producing a green body for a multilayer ceramic capacitor according to claim 1, wherein the solvent is a lower alcohol, the second organic binder is a cellulosic resin, and the second solvent is a high-chain saturated hydrocarbon. 3. The second organic binder is either polyvinyl alcohol or polyvinyl butyral,
The method for producing a green body for a multilayer ceramic capacitor according to claim 1, wherein the solvent is a lower alcohol, the first organic binder is a cellulosic resin, and the first solvent is a high-chain saturated hydrocarbon. 4. The production of a green body for a laminated ceramic capacitor according to claim 2, wherein the lower alcohol is a hydrocarbon having 2 to 6 carbon atoms and the high chain saturated hydrocarbon is a hydrocarbon having 8 to 12 carbon atoms. Method.