JP6939015B2 - Conductive paste for gravure printing for internal electrodes of multilayer ceramic capacitors - Google Patents

Description

The present invention relates to a conductive paste, more particularly to a conductive paste for an internal electrode of a multilayer ceramic capacitor, and more particularly to a conductive paste for gravure printing.

With the miniaturization of electronic devices such as mobile phones and digital devices, the size, capacity, and performance of multilayer ceramic capacitors (Multi-Layer Ceramic Capacitors, hereinafter referred to as "MLCCs"), which are chip components, have also increased. It is progressing. The most effective means for realizing these is to thin the internal electrode layer and the dielectric layer to form multiple layers.

This MLCC is generally manufactured as follows. In order to form a dielectric layer, first _{a dielectric such as barium titanate (BaTIO 3} ) is used as a main component, and this dielectric is dispersed in an organic resin binder such as polyvinyl butyral and then dried to obtain a dielectric green. Make a sheet. On the obtained green sheet, a conductive paste containing a conductive powder as a main component and dispersed in a vehicle containing an organic resin binder and a solvent is printed in a predetermined pattern and dried to remove the solvent inside. A dry film to be an electrode is formed. Next, the dielectric green sheet on which the dry film to be the internal electrode is formed is pressed in a state of being stacked in multiple layers, pressure-bonded and integrated, and then cut, and in an oxidizing atmosphere or an inert atmosphere. For the purpose of removing the organic resin binder, heat treatment is performed at a temperature of 500 ° C. or lower to remove the binder, and then the internal electrode and the dielectric are heated and fired at about 1300 ° C. in a reducing atmosphere so that the internal electrode is not oxidized. Is integrally sintered. Next, both ends of the fired chip are polished to expose the internal electrodes, and then an external electrode paste is applied to the end faces thereof and fired to form an external electrode, and then nickel plating or the like is applied on the external electrode to MLCC. To make.

However, in this firing step, the temperature at which the dielectric layer begins to sinter is about 1200 ° C., which is higher than the temperature at which conductive powder such as nickel starts sintering and shrinking, so delamination (delamination). And structural defects such as cracks may occur. In particular, as the size and capacity increase, the number of layers increases or the thickness of the dielectric layer decreases, and the occurrence of structural defects becomes remarkable accordingly.

Therefore, usually, in the nickel paste for internal electrodes, titanium having a composition similar to that of the dielectric layer is used to control the sintering / shrinkage of the conductive powder up to a temperature near the temperature at which the dielectric layer starts sintering / shrinking. A ceramic powder containing a perovskite-type oxide such as barium acid acid or strontium zirconate as a main component is added. By controlling the sintering behavior of the nickel powder, these ceramic powders can reduce the mismatch of the sintering shrinkage behavior of the internal electrode layer and the dielectric layer. Further, when a ceramic powder having a composition similar to that of the dielectric layer is added, the dielectric loss caused by the difference between the constituent elements of the main component of the dielectric layer and the constituent elements of the dielectric powder contained in the conductive paste for the internal electrode is generated. It may have the effect of reducing.

By the way, many of the above-mentioned conductive pastes for internal electrodes for MLCC have been conventionally used for screen printing. However, due to demands for cost reduction and productivity improvement, gravure printing, which has a higher printing speed than screen printing and is expected to improve productivity, has attracted attention, and a conductive paste that can be used for gravure printing has been demanded.
Since the printing speed of gravure printing is faster than that of screen printing, the viscosity of the gravure printing paste at the time of printing must be lower than the viscosity of the screen printing paste in order to print at that speed. .. On the other hand, when the viscosity after printing or during storage is low, the paste tends to flow, and the conductive powder having different specific densities and the dielectric powder as a sintering adjuster are likely to be separated. In order to obtain sufficient characteristics in gravure printing, a conductive paste having a low viscosity during printing and a viscosity that does not easily deform after printing and does not separate the conductive powder and the dielectric powder during storage is required.

For example, in Patent Document 1, in a gravure electrode ink containing a base metal powder containing nickel as a main component, 1 part by weight or more and 15 parts by weight or less of a resin and 20 parts by weight of an organic solvent are used with respect to 100 parts by weight of the metal powder. A gravure electrode ink characterized in that it is 150 parts by weight or less, has a viscosity of 10 poisons or less, and agglomerates of 10 μm or more are removed is disclosed.

Further, Patent Document 2 describes for an internal electrode of a multilayer ceramic capacitor containing a conductive powder (A), an organic resin (B), an organic solvent (C), an additive (D), and a dielectric powder (E). A conductive paste in which the organic resin (B) is composed of polyvinyl butyral having a degree of polymerization of 10,000 or more and 50,000 or less and ethyl cellulose having a weight average molecular weight of 10,000 or more and 100,000 or less, and the organic solvent (C) is propylene glycol monobutyl ether. Alternatively, it is composed of either a mixed solvent of propylene glycol monobutyl ether and propylene glycol methyl ether acetate, or a mixed solvent of propylene glycol monobutyl ether and mineral spirit, and the additive (D) is composed of a separation inhibitor and a dispersant, and the separation inhibitor is used. A conductive paste for gravure printing is disclosed, which comprises a composition containing a polycarboxylic acid polymer or a salt of the polycarboxylic acid as an agent.

Japanese Unexamined Patent Publication No. 10-335167 Japanese Unexamined Patent Publication No. 2012-174977

According to the technique described in Patent Document 1, a conductive paste for gravure printing that has low viscosity and does not cause separation of metal powder during printing can be obtained, but since it does not contain a dielectric powder as a sintering adjuster. , The timing of sintering the metal powder and the sintering of the dielectric cannot be matched, which may cause structural defects.

Further, in the technique described in Patent Document 2, in a conductive paste containing a dielectric powder, gravure printing is performed by using a mixed organic resin in which the degree of polymerization and the weight average molecular weight are specified, or a mixed organic solvent. Although it has a low viscosity suitable for, long-term storage may cause separation of metal powder.

The present invention has been made in view of the above-mentioned problems of the prior art, is particularly useful for an internal electrode of a multilayer ceramic capacitor, has a low viscosity suitable for gravure printing during printing, and is stored after printing or after manufacturing. It is an object of the present invention to provide a conductive paste in which reaggregation of conductive metal powder is sometimes suppressed, and it is difficult to be deformed and separated.

Therefore, in order to achieve the above object, the conductive paste for gravure printing for the internal electrode of the multilayer ceramic capacitor according to the present invention includes a conductive powder (A), an organic resin (B), an organic solvent (C), and an additive (D). ), And a conductive paste for gravure printing for an internal electrode of a multilayer ceramic capacitor containing a dielectric powder (E), wherein the conductive powder (A) is made of nickel powder, and the conductive powder (A). The content of the organic resin (B) with respect to the total amount of the conductive paste is 40% by mass or more and 60% by mass or less, the organic resin (B) is composed of only ethyl cellulose, and the content of the organic resin (B) with respect to the total amount of the conductive paste is 1.5% by mass. % Or more and 6% by mass or less, the organic solvent (C) is composed of only tarpineol, and the additive (D) is composed of a composition containing an unsaturated carboxylic acid-based dispersant and an oleylamine-based dispersant. The content of the unsaturated carboxylic acid-based dispersant in the agent (D) with respect to the total amount of the conductive paste is 0.2% by mass or more and 1.2% by mass or less, and the content of the oleylamine-based dispersant with respect to the total amount of the conductive paste is 0. It is 3% by mass or more and 0.5% by mass or less, the dielectric powder (E) is made of barium titanate, and the content of the dielectric powder (E) is 2% by mass with respect to the total amount of the conductive paste. When the conductive paste for the internal electrode of the laminated ceramic capacitor is placed in a container and left at a temperature of 25 ° C. for 30 days, the conductive powder (A) and the dielectric powder (E) are formed in an amount of 15% by mass or less. It has the property of maintaining a non-separable state, and has a viscosity of 0.05 Pa · s or more and 0.3 Pa · s or less at a ^{share rate of 10000 s -1 at room temperature, and a viscosity of 1 Pa · s at a share rate of 10 s -1.} It is characterized by being s or more.

According to the present invention, a predetermined amount of an organic solvent consisting only of tarpineol and an organic resin consisting only of ethyl cellulose are contained, and a predetermined amount of an unsaturated carboxylic acid-based dispersant and a predetermined amount of an oleylamine-based dispersant are contained. Even if the viscosity at the time of printing, which can be confirmed by the viscosity at the time of high-speed sharing with a share rate of 10000s ^-1 , is low, the viscosity at the time of printing or storage, which can be confirmed by the viscosity at the time of low-speed sharing at the ^{share rate of 10s -1, is long-term.} It has a value that can maintain the dispersed state, can prevent the separation of the conductive powder and the dielectric powder, and even if it is used after being stored for a long period of time, the viscosity does not change and the printed film can be printed. A conductive paste for gravure printing for an internal electrode of a multilayer ceramic capacitor that can be used without becoming non-uniform or deteriorating the smoothness of the film can be obtained.

Hereinafter, the conductive paste for gravure printing for the internal electrodes of the multilayer ceramic capacitor of the present invention will be described in detail.
The conductive paste for gravure printing for the internal electrodes of the multilayer ceramic capacitor of the present invention includes a conductive powder, an organic resin consisting only of ethyl cellulose, an organic solvent consisting only of tarpineol, an unsaturated carboxylic acid-based dispersant, and an oleylamine-based dispersion. It consists of an additive consisting of an agent and a dielectric powder.
As a result of diligent research, the present inventor has conventionally used a conductive powder in an organic resin binder in a conductive paste having excellent dispersibility using only ethyl cellulose as an organic resin and only tarpineol as an organic solvent. When a predetermined amount of the unsaturated carboxylic acid-based dispersant and the oleylamine-based dispersant are contained as the acid-based dispersant and the amine basic dispersant added for dispersion, the share rate at room temperature is 10000s- ¹ . When the viscosity of the conductive paste is 0.05 Pa · s or more and 10 Pa · s or less, and the share rate at room temperature is 10 s ^-1 , the viscosity of the conductive paste becomes 0.5 Pa · s or more in gravure printing. It has been found that it is suitable for both forming a printing film during high-speed printing and maintaining the shape of a printed matter after printing, and can prevent the conductive powder and the dielectric powder from separating in a short time. Hereinafter, the conductive paste for gravure printing for the internal electrodes of the multilayer ceramic capacitor of the present invention and its constituent materials will be described in more detail.

<Conductive powder>
As the conductive powder used for the conductive paste for gravure printing for the internal electrode of the multilayer ceramic capacitor of the present invention, nickel powder, copper powder, silver powder, palladium powder and the like can be used, but nickel powder is used. Is preferable.
With the miniaturization of electronic components such as MLCCs, it is necessary to improve the smoothness of the dry coating film and the density of the dry film in order to form a thinner and thinner conductor such as an internal electrode. Therefore, the particle size of the conductive powder is preferably 0.05 μm or more and 0.5 μm or less.
If the particle size of the conductive powder is less than 0.05 μm, the specific surface area of the particles becomes too large, so that the surface activity of the conductive powder becomes too high, which not only adversely affects the drying and debindering properties, but also adversely affects the drying and debindering properties. It is not preferable because it becomes difficult to obtain appropriate viscosity characteristics and the conductive paste may be deteriorated during long-term storage.
On the other hand, if the particle size exceeds 0.5 μm, the film-forming property when the paste coating film is thinned deteriorates, a predetermined capacitance cannot be obtained, or the dry film has insufficient smoothness. Moreover, the filling of the conductive powder is insufficient, and the desired dry film density cannot be secured, which makes it difficult to form a sufficiently thin and thin uniform internal electrode, which is not preferable. The preferable particle size of the conductive powder is 0.1 μm or more and 0.4 μm or less.
In the present invention, the particle size of the conductive powder is a particle size calculated from the specific surface area value obtained based on the BET method unless otherwise specified. The calculation formula is shown in Equation 1.

(Formula 1)

Particle size of conductive powder = 6 / (SA1 × ρ1)

SA1; Specific surface area value of conductive powder (BET method)
ρ1; True density of conductive powder (eg 8.9 for nickel)

The content of the conductive powder with respect to the total amount of the conductive paste is preferably 40% by mass or more and 60% by mass or less. If the content of the conductive powder is less than 40%, the electrode thickness after firing may become too thin, or the electrode film may not be sufficiently formed, resulting in an increase in resistance value or loss of conductivity. , The desired capacitance may not be obtained. On the other hand, if the content of the conductive powder exceeds 60%, it may be difficult to thin the electrode film.

<Organic resin>
Only ethyl cellulose is used as the organic resin. Ethyl cellulose is an organic resin component that has been conventionally excellent in solubility in a solvent, printability, combustion decomposition property, etc., and is suitably used for a conductive paste for an internal electrode of MLCC. Various other organic resins are used in the existing conductive paste, but the conductive paste for gravure printing of the present invention is required to have uniform printing even in high-speed printing due to its characteristics, and the organic resin. By using only ethyl cellulose in the paste, the variation during high-speed printing can be minimized.
The content of the organic resin using only ethyl cellulose with respect to the total amount of the conductive paste is preferably 1.5% by mass or more and 6% by mass or less. If it is less than 1.5% by mass, the strength of the dry film is lowered, the adhesion between the conductive film formed by the conductive paste and the dielectric sheet is deteriorated, and the conductive film is easily peeled off from the dielectric sheet. In some cases. As the content of the organic resin increases, the debindering property deteriorates, but as a result of trial and error, the present inventor has obtained a conductive powder, an organic resin consisting only of ethyl cellulose, an organic solvent consisting only of tarpineol, and an unsaturated carboxylic acid. By using an additive composed of an acid-based dispersant and an oleylamine-based dispersant and a conductive paste composed of a dielectric powder, the debinder property does not deteriorate even if the content of the organic resin exceeds 5% by mass. The paste was derived. However, if the content of the organic resin exceeds 6% by mass, the debinder property may be deteriorated due to the increase in the content of the organic resin.

<Organic solvent>
Only terpineol is used as the organic solvent. Like ethyl cellulose, tarpineol is an organic solvent that has been used conventionally, and has good compatibility with conductive metal powder, can produce a conductive paste in a short time, and uniformly disperses conductive metal powder and dielectric powder. It has an effect that is easy to do. In the gravure printing of the present invention, a conductive paste having more excellent dispersibility is required than before, and it is essential to use only terpineol as an organic solvent, whereby the conductive paste having excellent dispersibility is obtained. be able to.
The content of the organic solvent using only tarpineol is such that the viscosity of the conductive paste is suitable for gravure printing at the time of printing, and the shape after printing and the dispersed state at the time of storage after manufacturing can be maintained for a long period of time. It is adjusted and contained so as to have a viscosity that can prevent the separation of the dielectric powder.
The viscosity of the conductive paste suitable for high-speed printing in gravure printing is 0.05 Pa · s or more and 10 Pa · s or less at a ^{share rate of 10000s-1 at room temperature.}
If the viscosity of the conductive paste at a share rate of 10000s- ¹ at room temperature is less than 0.05 Pa · s, the viscosity becomes too low and problems such as bleeding occur during high-speed printing. On the other hand, if ^{the viscosity of the conductive paste at a share rate of 10000s-1} at room temperature exceeds 10 Pa · s, the viscosity becomes too high and problems such as fading occur during high-speed printing.
In addition, the viscosity of the conductive paste, which can maintain the shape after printing and the dispersed state during storage after production for a long period of time and prevent the separation of the conductive powder and the dielectric powder, has a shear rate of 10 s ^{-1 at room temperature.} Sometimes it is 0.5 Pa · s or more.
If the viscosity of the conductive paste at a share rate of 10 s ^-1 at room temperature is less than 0.5 Pa · s, the shape after printing and the dispersed state during storage after production cannot be maintained for a long period of time, and the conductive powder and the dielectric cannot be maintained. Body powder is prone to separation.

<Additives>
As the additive, a composition containing an unsaturated carboxylic acid-based dispersant and an oleylamine-based dispersant is used. Since the conductive paste for gravure printing of the present invention is used for high-speed printing, it is required to minimize various variations and obtain a conductive paste having excellent dispersibility. However, only the above-mentioned ethyl cellulose and tarpineol improve the dispersibility. That's not enough. However, the present inventor can add a composition containing an unsaturated carboxylic acid-based dispersant and an oleylamine-based dispersant as additives to further improve the dispersibility and obtain an excellent conductive paste for gravure printing. I found out what I could do.
The content of the unsaturated carboxylic acid-based dispersant is 0.2% by mass or more and 1.2% by mass or less with respect to the total amount of the conductive paste, and the content of the oleylamine-based dispersant is 0.3% by mass. It is 0.5 % by mass or less. When each dispersant is less than the above range, the viscosity range suitable for maintaining the shape after printing and the dispersed state for a long period of time during storage after production (viscosity range at room temperature share rate 10s ^-1 : 0.5 Pa ·. It deviates from (s or more), the dispersion effect is not sufficiently exhibited, and a separation phenomenon of the conductive powder and the dielectric powder occurs. Further, when each dispersant exceeds the above range, the dispersion effect is exhibited, but the excess additive deteriorates the viscosity of the conductive paste, and the viscosity range is suitable for high-speed printing for gravure printing. In some cases , the viscosity at room temperature at a share rate of 10000 s ^-1 is less than 0.05 Pa · s.
As the additive, in addition to the above-mentioned dispersant, the conductive paste of the present invention maintains the above-mentioned ^{viscosity characteristics when the share rate is 10000s -1} at room temperature and the viscosity characteristics when the share rate is 10s ^-1. Separation inhibitors and the like can also be added to the extent possible.

<Dielectric powder>
_{As the dielectric powder, a powder such as BaTiO 3} used for a normal conductive paste can be used. Moreover, this BaTiO ₃ as a main component, Mn, Cr, Si, Ca , Ba, Mg, V, W, Ta, may be a powder containing as a subcomponent to an oxide of Nb and rare earth elements, Ba of BaTiO ₃ A perovskite-type oxide ferroelectric powder in which an atom or Ti atom is replaced with another atom, Sn, Pb, Zr, or the like may be used. Furthermore, ZnO (zinc oxide), ferrite, PZT (lead zirconate titanate), BaO (barium oxide), Al ₂ O ₃ (aluminum oxide), and Bi ₂ O ₃ (oxidation), which are powders forming a green sheet of MLCC. In some cases, the dielectric loss can be reduced by selecting oxides such as bismuth), R ₂ O ₃ (rare earth oxide: R = rare earth element), TiO ₂ (titanium oxide), and Nd ₂ O _{3 (neodim oxide).} It is more preferable because there is.
The particle size of the dielectric powder is preferably in the range of 0.01 μm or more and 0.5 μm or less. If the particle size of the dielectric powder is less than 0.01 μm, the specific surface area of the particles becomes too large, so that the surface activity of the dielectric powder becomes too high, which not only adversely affects the drying and debindering properties, but is also appropriate. It is not preferable because it becomes difficult to obtain a good viscosity characteristic and the conductive paste may be deteriorated during long-term storage.
Further, when the particle size of the dielectric powder exceeds 0.5 μm, the film forming property when the paste coating film is thinned deteriorates, the filling of the dielectric powder becomes insufficient, and the smoothness at the time of forming the dry film. Is insufficient, the desired dry film density cannot be secured, it becomes difficult to form a sufficiently thin and thin uniform internal electrode, and a predetermined capacitance may not be obtained, which is not preferable. A more preferable particle size of the dielectric powder is 0.01 μm or more and 0.3 μm or less.
The content of the dielectric powder in the conductive paste of the present invention is preferably 2% by mass or more and 15% by mass or less. If the content of the dielectric powder is less than 2% by mass, the shrinkage of the electrode may not be sufficiently suppressed, while if the content of the dielectric powder exceeds 15% by mass, the electrode becomes too thick. , The electrode may be interrupted due to a decrease in metal content.

<Conductive paste>
In the conductive paste of the present invention, first, an organic resin is dissolved in an organic solvent to prepare an organic vehicle, and then a conductive powder, a dispersant as an additive, and a dielectric powder are added to the organic vehicle. Obtained by dispersing.
The organic vehicle can be obtained by adding an organic resin consisting only of ethyl cellulose to an organic solvent consisting only of terpineol heated to 50 ° C. or higher and 60 ° C. or lower, and mixing and stirring the mixture.
Next, an additive consisting of a conductive powder, a dielectric powder, a prepared organic vehicle, and a composition containing an unsaturated carboxylic acid-based dispersant and an oleylamine-based dispersant is weighed in a predetermined amount, put into a mixer, and stirred. , The conductive powder, the additive and the dielectric powder are uniformly dispersed and mixed in the organic vehicle by a three-roll mill to obtain a conductive paste.
The conductive paste of the present invention has a viscosity of 0.05 Pa · s or more and 10 Pa · s or less at a ^{share rate of 10000s-1 at room temperature.} If the viscosity of the conductive paste at a share rate of 10000 s ^-1 at room temperature is less than 0.05 Pa · s, the print width when the conductive paste is printed at high speed cannot be maintained, and bleeding occurs after printing, which is necessary. The film thickness cannot be secured. On the other hand, if ^{the viscosity of the conductive paste at a share rate of 10000s -1} at room temperature exceeds 10 Pa · s, the followability when printing at high speed is not sufficiently exhibited, and the conductive paste is sufficient for the cylinder for gravure printing. Problems such as chipping in the printed portion without filling, or the conductive paste not being transferred cleanly from the concave portion of the cylinder during printing, resulting in stains on the printed matter and uneven shading occur. When the viscosity of the conductive paste at a share rate of 10000s- ¹ at room temperature is 0.05 Pa · s or more and 0.3 Pa · s or less, the viscosity is sufficiently low and high-speed printing can be sufficiently supported, which is preferable.
Further, the conductive paste of the present invention has a viscosity of 0.5 Pa · s or more at a ^{share rate of 10 s -1 at room temperature.} If the viscosity of the conductive paste at a share rate of 10 s ^-1 at room temperature is less than 0.5 Pa · s, it becomes difficult to maintain the shape of the printed matter such as wiring after printing the conductive paste, and the required wiring width and No thickness can be obtained. When the viscosity of the conductive paste at a share rate of 10s- ¹ at room temperature is 1 Pa · s or more, the shape of the wiring formed as a printed matter is hardly deformed, which is preferable.
Further, the conductive paste of the present invention does not separate the conductive powder and the dielectric powder after being allowed to stand for 30 days. When the conductive paste is separated, the separated and collected conductive powders agglomerate, and even if they are lightly kneaded before printing, the agglomeration is not improved and the dispersibility is inferior. The smoothness of the surface deteriorates.

Hereinafter, the present invention will be described in detail based on more specific examples, but the present invention is not limited to the examples.

(1) Composition of Conductive Paste As the conductive powder (A), a spherical Ni powder having a particle size of 0.3 μm was contained. The organic vehicle contained a mixture of ethyl cellulose as the organic resin (B) of the binder and terpineol as the organic solvent (C) by heating at 60 ° C. As the additive (D), an acid-based dispersant and a basic-based dispersant were mixed and contained in the types and formulations shown in Table 1. As the dielectric powder (E), spherical barium titanate having a particle size of 70 nm was contained. The composition of the conductive paste of each sample is shown in Table 1.
The content of the organic resin (B) in the organic vehicle was basically 1/10 of that of the conductive powder (A), but in order to confirm the effect of the organic resin (B), samples 22 to 25 The content of the conductive powder (A) remained constant, and only the content of the organic resin (B) was changed. Further, the content of the organic solvent (C) is the remaining amount when a predetermined amount of another material is contained with respect to 100% by mass of the conductive paste.

(2) Evaluation of Separability In the evaluation of the separability of the conductive paste, 100 g of the conductive paste for the sample was placed in a 100 ml container and left at a temperature of 25 ° C. for 30 days, and the conductive powder and the dielectric were evaluated. The presence or absence of separation of body powder was visually confirmed. The state where the dielectric powder (E) contained in the conductive paste is separated and the white supernatant portion can be confirmed is ×, and the state where the white supernatant portion is not present and the separation of the dielectric powder (E) cannot be confirmed is ○, Was judged. The evaluation results are shown in Table 1.

(3) Measurement of viscosity The viscosity of the conductive paste was measured using a rheometer. When the viscosity at high speed sharing of the share rate 10000s ^-1 is 0.05 Pa · s or more and 0.3 Pa · s or less, it is ○, and when it exceeds 0.3 Pa · s and is 10 Pa · s or less, it is Δ10 Pa · s. A case exceeding s was judged as x. Further, when the viscosity at low speed sharing of the share rate 10s ^-1 is 1 Pa · s or more, it is 〇, when it is 0.5 Pa · s or more and less than 1 Pa · s, it is Δ, and when it is less than 0.5 Pa · s, it is ×. Was judged. The measurement results of each are shown in Table 1.

As can be seen from the results in Table 1 above, the conductive powder (A) and the dielectric powder (E) are contained within the scope of the present invention, and an unsaturated carboxylic acid-based dispersant as an additive (D) and an unsaturated carboxylic acid-based dispersant are used. Sample 3 in which the content of the oleylamine-based dispersant is within the range of the present invention, only ethyl cellulose is contained within the range of the present invention as the organic resin (B), and only tarpineol is contained as the organic solvent (C). -6, 10 , 19, 20, 23, 24, 27, 28 did not separate the conductive powder (A) and the dielectric powder (E) even when left in a container for 30 days. and, the formation of the print layer during high-speed printing in grayed Labia printing, in the shape retention of the printed material after printing, had very suitable viscosity.
Further, the sample 18 in which the content of the conductive powder (A) is below the lower limit of the range of the present invention, the sample 22 in which the content of the organic resin (B) is below the lower limit of the range of the present invention, and the dielectric powder (E). ) Is below the lower limit of the range of the present invention , the sample 26 has a viscosity at low speed share of samples 3 to 6, 10, 19 , 20 , 23 for maintaining the shape of the printed matter after printing in gravure printing. , was low Kuna' compared to 24, 27, 28.
Further, the contents of the conductive powder (A) and the organic resin (B) each exceed the upper limit of the range of the present invention, and the contents of the sample 21 and the organic resin (B) exceed the upper limit of the range of the present invention. Sample 25, in which the content of the dielectric powder (E) exceeds the upper limit of the range of the present invention, has a viscosity during high-speed sharing for forming a printing film during high-speed printing in gravure printing, samples 3 to 6. , 1 0,19, 20, 23, 24, was a high Kuna' compared to 27, 28.

On the other hand, the content of at least one of the unsaturated carboxylic acid-based dispersant and the oleylamine-based dispersant as the additive (D) is lower than the range of the present invention, or the unsaturated carboxylic acid-based dispersant and the oleylamine-based dispersion. In Samples 1, 2, 8 and 9, which did not contain one of the agents, the conductive powder (A) and the dielectric powder (E) were separated after storage for 30 days. Further, the sample 7 in which the content of the unsaturated carboxylic acid-based dispersant as the additive (D) exceeds the upper limit value (1.2% by mass) of the present invention, and the oleylamine-based dispersant as the additive (D). In the sample 13 whose content greatly exceeded the upper limit value ( 0.5 % by mass) of the present invention, the conductive powder (A) and the dielectric powder (E) were not separated, but the share rate was 10000s- ¹ . The viscosity during high-speed sharing became too high, and blurring occurred during high-speed printing in gravure printing. Further, as the additive (D), a sample containing a non-saturated carboxylic acid-based dispersant or an oleylamine-based dispersant instead of at least one of the unsaturated carboxylic acid-based dispersant and the oleylamine-based dispersant. When 14 to 17 were left in a container for 30 days, the separation of the conductive powder (A) and the dielectric powder (E) could not be suppressed.

As described above, the conductive paste of the present invention has a low viscosity suitable for gravure printing and is excellent in long-term storage, and is particularly a laminated chip component of an electronic device such as a mobile phone or a digital device, which is becoming smaller and smaller. It can be suitably used as a material for internal electrodes of ceramic capacitors.

Claims (1)

A conductive paste for gravure printing for internal electrodes of multilayer ceramic capacitors containing conductive powder (A), organic resin (B), organic solvent (C), additive (D), and dielectric powder (E). hand,
The conductive powder (A) is made of nickel powder, and the content of the conductive powder (A) with respect to the total amount of the conductive paste is 40% by mass or more and 60% by mass or less.
The organic resin (B) is composed of only ethyl cellulose, and the content of the organic resin (B) with respect to the total amount of the conductive paste is 1.5% by mass or more and 6% by mass or less.
The organic solvent (C) consists only of terpineol.
The additive (D) comprises a composition containing an unsaturated carboxylic acid-based dispersant and an oleylamine-based dispersant, and the content of the unsaturated carboxylic acid-based dispersant in the additive (D) with respect to the total amount of the conductive paste. Is 0.2% by mass or more and 1.2% by mass or less, and the content of the oleylamine-based dispersant with respect to the total amount of the conductive paste is 0.3% by mass or more and 0.5% by mass or less.
The dielectric powder (E) is made of barium titanate, and the content of the dielectric powder (E) is 2% by mass or more and 15% by mass or less with respect to the total amount of the conductive paste.
When the conductive paste for the internal electrode of the multilayer ceramic capacitor is placed in a container and left at a temperature of 25 ° C. for 30 days, the conductive powder (A) and the dielectric powder (E) are maintained in a state in which they are not separated. Has characteristics and
Inside a multilayer ceramic capacitor having a viscosity of 0.05 Pa · s or more and 0.3 Pa · s or less at a share rate of 10000 s ^-1 at room temperature and a viscosity of 1 Pa · s or more at a ^{share rate of 10 s -1.} Conductive paste for gravure printing for electrodes.