JP2000276944A - Conductive paste and manufacture of ceramic electronic component using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve peeling property of inner electrode layers from a base film by mixing an organic binder, a plasticizer and an organic solvent into metal powder to obtain a paste with the mixing ratio of the organic binder and plasticizer controlled within a specific range, applying the paste on a base film face, and heat-transferring the dried inner electrode layers on a green sheet face. SOLUTION: Nickel powder of 100 pts.wt., ethyl cellulose of 6 pts.wt. as an organic binder, a plasticizer of 0-100 pts.wt. against the ethyl cellulose, and a mixture of aliphatic naphtha and terpineol of 60 pts.wt. as an organic solvent are mixed to obtain this conductive paste. The conductive paste mainly made of nickel is applied on a PET base film 6 in multiple inner electrode layers 2 by screen printing then dried. The inner electrode layers 2 having individual compositions and applied on the base film 6 are heat-transferred on a ceramic green sheet at the prescribed temperature and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste widely used for various electronic products such as an electronic tuner of a television passive device, a liquid crystal television, and a mobile phone, and a method of manufacturing a ceramic electronic component using the same. It is.

[0002]

2. Description of the Related Art FIG. 2 shows a multilayer ceramic capacitor as a typical example of a ceramic electronic component. In the figure, 1
Denotes a dielectric ceramic layer, 2 denotes an internal electrode layer, and 3 denotes an external electrode.

[0003] Hereinafter, a conventional method for manufacturing a ceramic electronic component will be described by taking, as an example, a method for manufacturing a multilayer ceramic capacitor which is a representative example of a ceramic electronic component.

A conventional method for manufacturing a multilayer ceramic capacitor is as follows. First, polyvinyl butyral as a binder component, benzyl butyl phthalate as a plasticizer component, and butyl acetate as a solvent component are added to a dielectric material powder such as barium titanate and mixed. After the slurry is formed, the slurry is applied on a base film such as PET using a doctor blade method and dried to form a ceramic green sheet for the dielectric ceramic 1 having a thickness of 5 to 50 μm.

Separately, a plurality of internal electrode layers 2 having a thickness of 2 to 4 μm are juxtaposed on a base film such as PET by a printing method using a conductive paste containing nickel as a main component. . When the thickness of the internal electrode layer 2 is small,
When the subsequent multilayer ceramic capacitor is fired, the internal electrode layer 2 contracts and becomes partially discontinuous, which may cause a decrease in capacitance.

Next, the internal electrode layer 2 applied to the base film surface is thermally transferred to the ceramic green sheet surface.
A plurality of ceramic green sheets subjected to thermal transfer are laminated and pressed to form a laminated green block (not shown). still,
The lamination of the ceramic green sheets is performed with a predetermined dimension shifted in the longitudinal direction of the internal electrode layer 2 transferred alternately one by one.

Next, the laminated green block is cut into a predetermined size and fired under a predetermined condition to produce a sintered body. The sintered body has a configuration in which internal electrode layers 2 are exposed on opposite end faces every other layer on both sides of the dielectric ceramic layer 1 on both end faces in the longitudinal direction.

An external electrode 3 is provided on the end surface of the obtained sintered body where the internal electrode layer 2 is exposed to complete a multilayer ceramic capacitor. For example, Japanese Patent Publication No. 5-25381 discloses the method.

[0009]

However, when the internal electrode layer 2 applied on the base film is thermally transferred to the ceramic green sheet surface, the internal electrode layer 2 may not be completely transferred to the ceramic green sheet surface. In this case, the internal electrode layer 2 becomes discontinuous in the sintered body, and the designed capacitance cannot be obtained. Further, when the internal electrode layer 2 adheres to the base film when the base film is peeled after the internal electrode layer 2 is thermally transferred,
The ceramic green sheet is adhered and peeled to the adhered portion, and the dielectric ceramic layer 1 in the portion is missing, and a short circuit failure between the internal electrode layers 2 in the sintered body, a cause of cracks and structural defects of the sintered body are caused. It may be.

The present invention has been made in view of the above problems, and has been developed by applying an internal electrode layer to a base film by using a conductive paste capable of reliably transferring the internal electrode layer from the base film to the surface of the ceramic green sheet. An object of the present invention is to provide a method for manufacturing a ceramic electronic component having stable electrical characteristics without occurrence of structural defects or the like by using the same.

[0011]

In order to solve the above-mentioned problems, the present invention provides a method of mixing an organic binder, a plasticizer and an organic solvent with a metal powder, and adjusting the mixing ratio of the organic binder and the plasticizer to 100: 60. Using a conductive paste controlled in the range of ~ 100, this was applied to the base film surface, and the dried internal electrode layer was thermally transferred to the green sheet surface, and was coated by using this conductive paste. The internal electrode layer has good releasability from the base film and can achieve the intended purpose.

In general, a conductive paste for an internal electrode used in the manufacture of a ceramic electronic component lowers the elastic modulus and glass transition point of an organic binder contained in the conductive paste, so that printing,
A plasticizer may be added to ensure moldability,
In order to simply improve the printing and moldability, the ratio depends on the type of the organic binder used, but the ratio of the plasticizer to the organic binder 100 is 50 or less. The conductive paste of the present invention improves the releasability of the internal electrode layer from the base film by using a mixture of 60 or more plasticizers with 100 organic binders, and enables reliable thermal transfer to the ceramic green sheet surface. Becomes That is, a large amount of plasticizer is adsorbed on the surface of the organic binder molecules, thereby reducing the intermolecular adsorption force acting between the base film surface and the organic binder in the applied internal electrode layer, and reducing the adhesive force. The weakening is based on a mechanism that the peeling from the base film is facilitated and the thermal transfer can be reliably performed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention relates to a conductive paste used for coating and forming a conductive layer made of a metal powder, an organic binder and a plasticizer on a base film surface. 100 with plasticizer
It is a conductive paste characterized by adding an appropriate amount of an organic solvent to the conductive paste, and adding a plasticizer to the organic binder 100 of the conductive paste by 60 to 100.
By using the mixture, a large amount of plasticizer is adsorbed on the surface of the organic binder molecules, reducing the intermolecular adsorption force acting between the base film surface and the organic binder in the internal electrode layer formed by coating, To weaken the adhesive strength,
It has an effect that the peeling from the base film is facilitated and the thermal transfer can be reliably performed.

According to a second aspect of the present invention, there is provided the conductive paste according to the first aspect, wherein a phthalate-based material is used as a plasticizer. The plasticizer has a large effect of further reducing the intermolecular adsorption force between the organic binder contained in the conductive layer formed on the base film and the base film and facilitating the peeling of the conductive layer from the base film.

According to a third aspect of the present invention, there is provided a method for producing a ceramic green sheet from a slurry comprising a ceramic powder, an organic binder, and a plasticizer, and a method for producing a conductive sheet according to the first or second aspect on a film. Forming a conductive layer by applying a conductive paste, and a step of thermally transferring the conductive layer to the ceramic green sheet,
This is a method of manufacturing a ceramic electronic component in which a plurality of ceramic green sheets to which a conductive layer is thermally transferred are laminated to form a laminated green block. By thermal transfer to, the occurrence of structural defects was suppressed,
It is possible to obtain a ceramic electronic component having stable electric characteristics.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a ceramic electronic component according to the third aspect, wherein a material having a critical surface tension of a film on which a conductive layer is applied and formed is larger than a surface tension of a conductive paste. Method, thereby improving the wettability of the conductive paste on the base film surface,
It is easy to form a conductive layer having accurate dimensions on the base film without repelling the conductive paste when forming the conductive layer by coating.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, using a multilayer ceramic capacitor as a representative example of a ceramic electronic component.

FIG. 1 is a cross-sectional view of the internal electrode layer 2 formed on the base film 6 of the present embodiment by coating, and FIG. 3 is a cross-sectional view of the dielectric ceramic layer ceramic green sheet 4 formed on the base film 5. is there. In FIG. 2, the finished product of the multilayer ceramic capacitor is the same as that of the conventional example, and is used.

The manufacturing method of the multilayer ceramic capacitor is as follows.
First, polyvinyl butyral as a binder component, benzyl butyl phthalate as a plasticizer component, and butyl acetate as a solvent component are added to a dielectric material powder such as barium titanate to form a slurry, and then the slurry is formed. The slurry is applied to the surface of a base film 5 made of a resin and dried to prepare a ceramic green sheet 4 for the dielectric ceramic layer 1 having a thickness of 9 μm.

Separately, a plurality of 2.5 μm-thick internal electrode layers 2 are provided in parallel on a surface of a PET base film 6 by a screen printing method on a surface of a PET base film 6. After that, drying is performed. Internal electrode layer 2
When the thickness is small, the internal electrode layer 2 shrinks during firing of the multilayer ceramic capacitor and becomes partially discontinuous, which may cause a decrease in capacitance. It was applied to a thickness of 2.5 μm. The conductive paste was 100 parts by weight of nickel powder, 6 parts by weight of ethyl cellulose as an organic binder, 0 to 100 parts by weight of a material shown in Table 1 with respect to ethyl cellulose as a plasticizer, and a mixture of aliphatic naphtha and terpineol as an organic solvent. A mixture of 60 parts by weight was used.

The base film 6 has a critical surface tension of 35 dyne / cm and is larger than the surface tension of each conductive paste. Thereby, consideration was given so that the internal electrode layer 2 could be applied and formed with high accuracy on the surface of the base film 6 during printing of the conductive paste. When the surface tension of the conductive paste becomes larger than the critical surface tension of the base film 6,
The wettability between the conductive paste and the base film 6 decreases,
At the time of printing, repulsion occurs, and it becomes impossible to apply the internal electrode layer 2 with high accuracy.

Next, the internal electrode layers 2 having the respective compositions formed by coating the ceramic green sheets 4 on the base film 6 are subjected to thermal transfer at 85 ° C. and a pressure of 12 MPa.

Separately, the ceramic green sheet 4 formed on the surface of the base film 5 is peeled off, and a plurality of sheets are laminated and pressed to produce upper, lower and ineffective layers (not shown).

Next, the first-layer ceramic green sheet 4 thermally transferred onto the lower ineffective layer is laminated and pressed, and then the second-layer ceramic green sheet 4 on which the internal electrode layer 2 is printed is applied to the first-layer ceramic green sheet 4. Of the internal electrode layer 2 is deviated by a predetermined dimension in the longitudinal direction, and is laminated and pressed. Further, the ceramic green sheet 4 on which the third-layer internal electrode layer 2 is printed is laminated and pressed so as to overlap directly on the first-layer internal electrode, and the fourth-layer internal electrode layer 2 is further formed thereon. Are laminated and pressed. In this way,
After laminating 100 layers of the ceramic sheets 14 on which the internal electrode layers 2 are printed alternately one by one by a predetermined size, and finally laminating and pressing the upper ineffective layer, a laminated green block (not shown) is laminated and pressed. Make it.

Then, the laminated green block is cut so as to have a size of 3.1 × 1.5 mm in length after firing to produce a green chip (not shown). The obtained green chip has a configuration in which the internal electrode layers 2 are alternately exposed at different end surfaces facing each other with the ceramic green sheet 4 interposed therebetween at both end surfaces in the longitudinal direction.

Next, the green chip is degreased at a temperature of 350 ° C. in the air, and then baked at a temperature of 1300 ° C. in a reducing atmosphere made of green gas to obtain a sintered body (not shown).
Get. The firing in a reducing atmosphere is performed for the purpose of preventing the internal electrode layer 2 from being oxidized since nickel is used for the internal electrode layer 2. The thickness of the dielectric ceramic layer 1 of the obtained sintered body was 5 μm, and the thickness of the internal electrode layer 2 was 1.8 μm.
Met.

Next, an external electrode 3 mainly composed of copper is formed at the end of the sintered body so as to be electrically connected to the internal electrode layers 2 exposed at both end surfaces of the sintered body, as shown in FIG. Complete the multilayer ceramic capacitor.

Thereafter, the capacitance of the completed multilayer ceramic capacitor, the appearance of the sintered body, the state of occurrence of internal structural defects, and the internal electrode layer 2
When the internal electrode layer 2 is thermally transferred to the surface of the ceramic green sheet 4, the ceramic green sheet 4
Evaluation was made based on the weight of the internal electrode layer 2 transferred to the surface and the weight of the remaining internal electrode layer 2, and the results are shown in Table 1 together.

[0029]

[Table 1]

As shown in Table 1, phthalic acid ester (dibutyl phthalate, benzyl butyl phthalate, di-2-ethylhexyl phthalate) was used as a plasticizer, and the amount of the phthalic acid ester was set to 60 or more with respect to 100 organic binders. The transfer of the conductive paste is almost certainly performed. However, when the transfer is less than 60, the transferability is reduced, the capacitance is low, and internal structural defects occur frequently. On the other hand, tricresyl phosphate and butyl oleate other than the phthalate ester improve the transferability as the added amount increases, but are not sufficiently satisfactory. From this result, it is clear that transferability to the ceramic green sheet 4 surface can be ensured by controlling the type of plasticizer in the conductive paste and the amount added to the binder. As a result, a reduction in capacitance due to transfer failure of the internal electrode layer 2 and the occurrence of internal structural defects in the sintered body are suppressed, and there is a great effect in producing a multilayer ceramic capacitor having stable characteristics with good yield.

Although the present embodiment has been described by taking a multilayer ceramic capacitor as an example, the present invention can be sufficiently applied to a method of manufacturing a multilayer varistor, a multilayer coil, a multilayer substrate, and the like of a general ceramic electronic component having a lamination process. be able to.

[0032]

As described above, according to the present invention, a conductive layer composed of a metal powder, an organic binder, and a plasticizer is applied to the base film surface, and the ratio of the organic binder to the plasticizer is 100%. 60 to 100 pairs,
By using a conductive paste formed by adding an appropriate amount of an organic solvent thereto, the conductive layer applied and formed on the base film surface can be efficiently thermally transferred to the ceramic green sheet. As a result, it is possible to produce a ceramic electronic component having a lamination process with a high yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conductive layer formed on a base film surface in a method for manufacturing a ceramic electronic component of the present invention.

FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor manufactured by the same method.

FIG. 3 is a sectional view of a ceramic green sheet of a dielectric ceramic layer formed on the base film surface.

[Explanation of symbols]

 Reference Signs List 1 dielectric ceramic layer 2 internal electrode layer 3 external electrode 4 ceramic green sheet 5, 6 base film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01G 4/30 301 H01G 4/30 301C (72) Inventor Shigeki Inagaki 1006 Odakadoma, Kadoma City, Osaka Matsushita Electric F-term (reference) in Sangyo Co., Ltd. 4J038 EA011 HA06 JA61 KA10 KA20 NA20 PB09 PC08 5E001 AB03 AC09 AE02 AE03 AF06 AH01 AH05 AH09 AJ01 5E082 AA01 AB03 BC38 EE04 EE23 EE35 FG06 FG12 JJ27 GG27 GG27 5G301 DA10 DA42 DD01

Claims (4)

[Claims] 1. A conductive layer comprising a metal powder, an organic binder, and a plasticizer is applied to a base film surface, and in a conductive paste used for formation, the ratio of the organic binder to the plasticizer is set to 100 to 60 to 100, A conductive paste containing an appropriate amount of an organic solvent. 2. The conductive paste according to claim 1, wherein a phthalate-based material is used as the plasticizer. 3. A step of preparing a ceramic green sheet from a slurry comprising a ceramic powder, an organic binder, and a plasticizer, and forming a conductive layer by applying the conductive paste according to claim 1 on the film. And a step of thermally transferring the conductive layer to the ceramic green sheet, and laminating a plurality of ceramic green sheets on which the conductive layer is thermally transferred to produce a laminated green block. 4. The method for manufacturing a ceramic electronic component according to claim 3, wherein a material having a critical surface tension of a film on which the conductive layer is applied is larger than a surface tension of the conductive paste.