JPH0917687A - Paste for inner electrode for laminated ceramic capacitor and its manufacture - Google Patents

Abstract

PURPOSE: To provide paste for inner electrode for laminated ceramic capacitor so as to effectively suppress the generation of sheet attack and delamination. CONSTITUTION: Dihydroterpineol is used for the resin solution of paste to be used for the inner electrode for a laminated ceramic capacitor, which is composed by combining with a dielectric green sheet that contains polyvinyl butyral as organic binder. Thus, high quality laminated ceramic capacitor is stably manufactured with high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste for an internal electrode of a laminated ceramic capacitor used in the field of manufacturing electronic parts and a method for manufacturing the same.

[0002]

2. Description of the Related Art As electronic parts are becoming lighter, thinner, shorter and smaller, there is an increasing demand for miniaturization and high capacity of multilayer ceramic capacitors (MLCC) which are chip parts. The most effective means for reducing the size and increasing the capacity of the MLCC is to reduce the thickness of the internal electrodes and the dielectric layer to achieve a multilayer structure.

The MLCC is generally manufactured through the following steps. That is, a palladium paste is screen-printed on a dielectric clean sheet made of a dielectric powder typified by barium titanate (BaTiO ₃ ) and an organic binder such as polyvinyl butyral, and dried. Next, the inner palladium electrodes are laminated so as to be alternately laminated, and then thermocompression bonded, and the thermocompression bonded body is cut into a target size. Subsequently, this is baked at about 1300 ° C. for the purpose of binder burnout and sintering of the internal palladium electrode and the dielectric, and an external electrode (usually silver is used) for coupling the MLCC and the external device. Is attached to the sintered body to form a product.

The internal electrode paste is composed of a metal powder made of fine powder of palladium or nickel, an organic binder made of cellulose-based or acrylic resin, and a solvent made of terpineol, trimethylbenzene, etc., and kneaded by a three-roll mill. Then, it is manufactured by mixing and dispersing. That is, the internal electrode paste is obtained by dissolving fine metal powder such as palladium in an organic vehicle obtained by dissolving a resin serving as an organic binder in an organic solvent, and adding a diluent for adjusting clay.

As the organic solvent in the organic vehicle, terpineol, trimethylbenzene, methyl ethyl ketone, etc. are usually used, and as the organic binder, a cellulose resin such as ethyl cellulose or nitrocellulose, or an acrylic resin such as butyl methacrylate or methyl methacrylate. Is used. In addition, the viscosity is generally 50,000 cps at 100 revolutions on a rotational viscometer.
It is adjusted as follows.

[0006]

In the manufacturing process of a multilayer ceramic capacitor (MLCC), defective products often occur when firing a thermocompression-bonded body of a dielectric green sheet screen-printed with an internal electrode paste. One of the causes is a delamination phenomenon that occurs between the dielectric layer and the internal electrode layer. Although various causes of delamination have been considered, the current situation is that sufficient delineation and countermeasures have not yet been taken.

The present inventors have noticed the relationship between mutual dissolution and delamination of the organic electrode paste in the internal electrode paste and the dielectric green sheet, and have found problems with the conventional internal electrode paste.

That is, in the internal electrode paste, ethyl cellulose is used as the organic binder, and terpineol (usually a simple substance or a mixture of α-type, β-type and γ-type terpineol isomers) is used as the organic solvent. This terpineol has a function (sheet attack) of dissolving polyvinyl butyral widely used as an organic binder in the dielectric green sheet. When this sheet attack occurs, the dielectric green sheet swells immediately after the internal electrode paste is printed on the green sheet to the firing step of the laminated body, causing delamination. When delamination occurs, MLCC
However, there is a problem that the withstand voltage property and the insulation property are deteriorated, the target electrostatic capacity cannot be obtained, and the load life characteristic is deteriorated.

The present invention eliminates the above-mentioned seat attack,
It is intended to propose a paste for an internal electrode of a multilayer ceramic capacitor that can effectively suppress the occurrence of delamination and a manufacturing method thereof.

[0010]

The present invention relates to a paste for internal electrodes of a laminated ceramic capacitor, which is formed by combining a dielectric green sheet containing polyvinyl butyral as an organic binder, the paste being in an organic vehicle of the paste. A paste for an internal electrode of a monolithic ceramic capacitor, wherein the paste contains dihydroterpineol. Further, the production method is characterized in that dihydroterpineol is used as the main component of the organic solvent used for dissolving the resin in the paste.

The multilayer ceramic capacitor (MLCC) produced by the method of the present invention is a multilayer laminate of a dielectric green sheet and an internal electrode paste. The dielectric green sheet is composed of a dielectric powder such as barium titanate and an organic binder of polyvinyl butyral. The internal electrode paste is composed of an organic binder made of a resin such as ethyl cellulose and an organic vehicle made of hydroterpineol, an electrode forming component made of a noble metal such as palladium or nickel, and a diluent solvent for adjusting clay.

[0012]

In the present invention, the reason why dihydroterpineol is used as the main component of the organic solvent used for dissolving the resin in the paste is as follows.
That is, the sheet attack, which is one of the causes of delamination, occurs because the organic solvent used in the dielectric green sheet, that is, polyvinyl butyral, is dissolved in the organic solvent in the internal electrode paste that is in contact with the organic binder. Therefore, it has a low solubility in the organic binder used for the dielectric green sheet, a high solubility in the ethyl cellulose resin used in the internal electrode paste, and the melt has an appropriate viscosity and drying property that can be used as a paste. Dihydroterpineol is suitable as the organic solvent.

The amount of dihydroterpineol in the organic vehicle of the internal electrode paste of the present invention is 80 to 50.
About 90% by weight is preferable. That is, when the amount of dihydroterpineol is less than 80% by weight, the solubility of ethyl cellulose is remarkably low, and the viscosity of the organic vehicle is remarkably high, so that the workability at the time of preparing the paste is remarkably deteriorated. On the other hand, when the amount of dihydroterpineol exceeds 90% by weight, the viscosity of the organic vehicle is too low to efficiently carry out kneading with a three roll mill or the like.

The amount of the palladium powder in the internal electrode paste of the present invention is preferably 40 to 60% by weight. That is, 40% by weight of palladium powder in the paste
If the amount is less than 60%, the electrode thickness after firing may be small, the resistance value may remarkably increase, the conductivity may be lost, and the target electrostatic capacity may not be obtained. This is because the electrode film thickness becomes large and causes delamination.

Further, the amount of the organic vehicle in the paste is preferably 20 to 40% by weight. The reason is 20
If it is less than 10% by weight, the strength of the dry film becomes small and scratches are likely to occur on the internal electrode surface after printing. On the other hand, if it exceeds 40% by weight, the electrode thickness after baking becomes small and the resistance value remarkably increases. In some cases, the conductivity as an electrode may be lost, and the desired electrostatic capacitance may not be obtained.

[0016]

【Example】

Example 1 Preparation of the organic vehicle used for the internal electrode paste is as follows.
It was performed by heating various solvents to a temperature of 80 ° C. in an oil bath and gradually adding the resin for organic binder while stirring with a stirring blade. Then, in order to confirm that the resin was completely dissolved, a part of the melted product was taken out and it was confirmed that the resin did not remain undissolved on the preparation.

The resin for the organic binder of the organic vehicle is a mixed solution of toluene and ethanol (weight ratio 1: 1).
When 5% of ethyl cellulose is dissolved, the viscosity is 15
Ethyl cellulose used was in the range of 0 cps to 250 cps. The composition of the produced organic vehicle is shown in Table 1.

In this embodiment, 35 g of the above organic vehicle,
Pb powder with an average particle size of 0.3 μm (trade name: SFP-30
1P, manufactured by Sumitomo Metal Mining Co., Ltd.), and 15 g of a diluent (trade name: Mineral Spirits A, manufactured by Nippon Oil Co., Ltd.) are weighed and sufficiently kneaded with a three-roll mill, and 1
00 g of Pb paste for internal electrodes was manufactured. The manufactured Pb paste was confirmed to have a viscosity of 100,000 or less at 50,000 cps by a Brookfield rotational viscometer.

Next, in order to examine the presence or absence of the sheet attack, dihydroterpineol, which is the organic solvent of the present invention, was added to the B-containing 35 μm thick B containing polyvinyl butyral resin.
aTiO ₃ type dielectric green sheet (30mm × 30m
One drop was dropped on m), and the time until the green sheet was attacked was visually measured. Table 2 shows the results.
Shown in

Further, the obtained internal electrode paste was screen-printed on the green sheet so as to have a thickness of about 15 μm, and the sheet was dried at 60 ° C. for 3 minutes. After that, the sheets are laminated, and the temperature is 80 ° C. and 100 kg / cm.
Thermocompression bonding was performed for 3 minutes under the conditions of No. ² to prepare a laminated body having 20 layers of internal electrodes. Then, the laminated body was cut into a 3 mm × 5 mm square and baked in an atmospheric furnace at 1350 ° C. for 2 hours. Then, the fired body was polished and the cross section was observed with an optical microscope to determine the number of delaminations. Table 3 shows the results.
Shown in The numbers in the table indicate the occurrence rate of delamination observed in 20 samples.

Comparative Example A terpineol conventionally used as a solvent for an internal electrode paste was subjected to a sheet attack test in the same manner as in Example 1 above, and the generation time thereof was measured. Next, an organic vehicle using this terpineol was produced by the same production method as in Example 1 at the compounding ratios shown in Table 1, and a paste was produced by the same compounding as in Example 1, and by the same method as in Example 1. The results of measuring the delamination generation rate are also shown in Table 3.

As is clear from the results of Table 2, the conventional terpineol has a sheet attack start time of 1 minute, whereas the organic solvent of the present invention has a sheet attack start time of 2.5 minutes or more, which is 2 minutes 40 seconds. It's getting longer. Table 3
As is clear from the result of the above, the conventional terpineol as a solvent has a delamination frequency of 13/3.
While the probability is 0 and the probability is 60% or more, the frequency using the organic solvent of the present invention is 6/20, that is, 30% or less.

[0023]

[Table 1]

[0024]

[Table 2] ◎: No seat attack ○: There is seat attack ×: Remarkable seat attack

[0025]

[Table 3]

[0026]

As described above, the internal electrode paste for a laminated ceramic capacitor of the present invention has the excellent effect of effectively suppressing the occurrence of sheet attack and delamination. It can be stably manufactured with a high yield.

Claims (2)

[Claims] 1. A paste for an internal electrode of a laminated ceramic capacitor, which is formed by combining a dielectric green sheet containing polyvinyl butyral as an organic binder, wherein the organic vehicle of the paste contains dihydroterpineol. A paste for an internal electrode of a multilayer ceramic capacitor, which is characterized by: 2. In a method for producing a paste for an internal electrode of a laminated ceramic capacitor, which is formed by combining a dielectric green sheet containing polyvinyl butyral as an organic binder, as a main component of an organic solvent used for dissolving the paste resin. A method for producing a paste for an internal electrode of a multilayer ceramic capacitor, characterized by using dihydroterpineol.