JPS6047314B2 - Binder composition for paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a binder composition used in producing a paste for forming a multilayer structure such as a multilayer ceramic substrate or a multilayer ceramic capacitor.

(2) Background of the technology Traditionally, dielectric layers and conductor layers are formed by screen printing, multilayered by repeated printing and drying, and then fired. There is a way to obtain ceramic capacitors.

The dielectric and conductor pastes used in this method are required to have the following properties. 1. It should not crack when drying, and should have appropriate flexibility and be easy to handle when removed from the stand used for printing (for example, an aluminum foil frame).

2. No pinholes should occur during drying.

3. It dries quickly and the viscosity does not easily change during printing.

4. Good leveling properties.

Generally, ethyl cellulose is used as a binder for thick film pastes.
Although nitrocellulose and the like are used, the above properties cannot be obtained with these binders alone.

Therefore, a binder having the above-mentioned properties is required. (
3) Purpose of the Invention Based on the above requirements, the present invention provides a binder system that, when added to a paste, has good leveling properties in printing, does not cause cracks or pinholes when drying, and has appropriate flexibility. The purpose is to provide a composition.

(4) Structure and object of the invention According to the present invention, a polyoxyethylene alkylamine surfactant is added as a dispersant to a binder consisting of ethyl cellulose, polyvinyl butyral, and n-dibutyl phthalate, and terpineol is added as a solvent. In the binder system for paste, the binder contains 60 to 75% by weight of ethyl cellulose and 5% by weight of polyvinyl butyral.
This is achieved by providing a binder system composition for a paste characterized by comprising ~17.5% by weight of n-dibutyl phthalate and 10-3% by weight.

(5) Examples of the invention Examples of the present invention will be described in detail below.

Example 1 Dielectric powder was BaTiO3 (average particle size 1.
3 μm), Pd as electrode powder (average particle size 0.9 μm)
A dielectric paste was prepared using the binder system A shown in Table 1.

However, the y number of the binder is the amount added per 100 y of raw material powder, and (%) is the ratio of each component to the total amount of the binder. Furthermore, the amount of binder added to the Pd paste is 0.0% of that of the dielectric paste. It was like that. Further, the amount of terpineol added varies depending on the type of binder. This addition was adjusted so that the viscosity of the paste was 50,000 CpS (at 27°C).

Note that since ethyl cellulose and polyvinyl butyral are polymers, their molecular weights and properties vary.

Here, a 10% ethanol/toluene solution having a viscosity of 30 to 6 CCpS was used. Using the above paste, print dielectric paste on aluminum foil, then alternately print 10 layers of conductive Pd paste and 25 pm thick (7) dielectric paste on top of that, and then dry at 120°C for 6 minutes. Summer. The results were as shown in Table 2. That is, sample A had pinholes in the dielectric layer, sample E was difficult to handle, and the conductor moved and misaligned, but sample B used a binder system with a composition within the scope of the claims of the present invention. ，
No problems occurred with C and D.

In addition, polyvinyl butyral resin and phthalic acid-n-
Dibutyl improves the properties of ethylcellulose, which is the main binder, and is added to prevent cracking and improve handling. However, if polyvinyl butyral is less than 5%, cracking will occur. It becomes easier.

If n-dibutyl phthalate is less than 10%, flexibility will be lost and handling will be poor, and if it is more than 35%, the drying rate will be slow. Also, the amount of binder added is 1 part of the raw material powder.
When it is less than 17y per 00y, cracks are likely to occur, and when it is more than 35y, the drying rate becomes slow and the firing shrinkage rate becomes too large. As the drying speed becomes slower, there is a greater possibility that conductor rubbing will occur when multiple layers are formed under the same drying conditions. Example 2 The binder system of sample c in Table 1 was adjusted to 0.6,0.
Dielectric pastes containing 8, 1.2, and 1.4 times the amount of the binder system of sample c were added to the conductor paste PdlOOy by 0.9 times, and multilayering was performed in the same manner as in the previous example. Summer.

The result is 0. In the case of Hao, cracks occurred during multilayering, and 1.
In the case of 4 times as much, misalignment of the conductor occurred, but no problem occurred in the other cases. As a result of burning out the samples in Examples 1 and 2 that did not cause any problem in multilayer structure and firing them at 1350° C., the desired multilayer structure was obtained.

The firing shrinkage rate at this time was 20 to 25%.Example 3 In Examples 1 and 2, terpineol was used as the solvent, but instead of terpineol, carbitol such as butyl carbitol or butyl carbitol acetate, etc. Even when carbitol acetate solvents were used, no problem occurred in multilayering.

(6) Effects of the Invention As explained in detail above, the binder composition for paste of the present invention makes the ceramic paste easy to handle, does not cause pinholes, cracks, etc. The substrate and the multilayer ceramic capacitor can be manufactured with high yield, and since pinholes in the dielectric can be completely eliminated, reliability is improved, which is a great effect.

Claims (1)

[Claims] 1. In a paste binder system in which a polyoxyethylene alkylamine surfactant is added as a dispersant to a binder consisting of ethyl cellulose, polyvinyl butyral, and n-dibutyl phthalate, and terpineol is added as a solvent, the binder is ethyl cellulose 60. 75% by weight of polyvinyl butyral, 5-17.5% by weight of polyvinyl butyral, and 10-30% by weight of n-dibutyl phthalate.