JP4356181B2 - Wet developer for circuit formation and circuit formation method using this developer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit-forming wet developer and a circuit-forming method using the developer, in particular, a circuit-forming wet developer used for forming a circuit pattern on a transfer medium by wet electrophotography and the development. The present invention relates to a circuit forming method using an agent.
[0002]
[Prior art]
In recent years, an electrophotographic method has been proposed as a novel circuit forming method that replaces the wiring printing method using a screen mask. In this method, a charge image (electrostatic latent image) in the form of a circuit pattern is formed on the surface of the photosensitive member, and a charged powder for circuit formation (hereinafter referred to as circuit forming toner) is statically applied to the electrostatic latent image. The toner is electrically attached, and an image of a circuit pattern-like circuit forming toner is transferred onto a transfer medium such as a ceramic green sheet, and then fixed.
[0003]
As a developing method for circuit forming electrophotography, a dry two-component magnetic brush developing method using a magnetic carrier in addition to a circuit forming toner and a dry one-component non-magnetic developing method using no carrier are known. . Examples of the former include JP-A-56-167388, JP-A-59-40597, and JP-A-2-257696, and examples of the latter include JP-A-11-177213. .
[0004]
In any conventional circuit forming method using electrophotography, a dry developer is used, so that the particle size of the charged powder for circuit formation contained in the developer is as large as about 3 to 20 μm. However, while the conductor film thickness is increased and the electrical resistance can be reduced, the accuracy of the circuit line width is about ± 20 μm with respect to the intended width.
[0005]
In contrast to such a circuit forming method using a dry developer, Japanese Patent Application Laid-Open Nos. 7-86720 and 7-92718 propose a circuit forming method using a wet developer. This wet developer contains a metal or its oxide and resin as main components, and a charge control agent and a dispersion medium are added to this and kneaded, and the toner particle size is 0.01 to 10 μm, preferably 0.1 to 5 μm. This developer is transferred to a transfer material mainly composed of talc and metal fluorosilicate.
[0006]
[Problems to be solved by the invention]
However, in the case of the circuit forming toner formed by kneading the metal powder and the resin powder and then pulverizing, the resin film on the metal powder is not uniform and the metal powder may be exposed from the resin film. Thus, the toner charge amount distribution cannot be made uniform. For this reason, development variation is large, and a dense circuit pattern cannot be obtained.
[0007]
Accordingly, an object of the present invention is to provide a circuit-forming wet developer capable of forming a precise circuit pattern with high line width accuracy and a circuit-forming method using the developer, as a developer for forming a circuit by electrophotography. There is to do.
[0008]
[Means for Solving the Problems]
The object is achieved by the invention according to claim 1 or 3 .
According to a first aspect of the present invention, there is provided a wet developer for forming a circuit for forming a circuit pattern on a transfer medium by wet electrophotography, wherein metal or metal oxide particles are used as a core, and the surface of the core is formed. Core / shell type composite particles encapsulated by coating a thermoplastic resin by a polymerization method are dispersed in a solvent, and the content ratio of the metal or metal oxide to the resin is 80:20 to 95: 5 wt%. And the solvent has a viscosity of 15 to 20 cSt .
According to a third aspect of the present invention, there is provided a step of forming a circuit pattern-shaped electrostatic latent image on the surface of the photosensitive member, and a circuit formation according to the first or second aspect with respect to the electrostatic latent image on the photosensitive member. Developing a wet developer, a step of transferring a circuit pattern image of the wet developer on the photosensitive member onto the transfer member, a step of fixing the circuit pattern image transferred onto the transfer member, A circuit forming method characterized by comprising:
[0009]
As shown in FIG. 1, the wet developer according to claim 1 is a core / shell type in which metal or metal oxide particles are used as a core C and the surface thereof is coated with a thermoplastic resin R by a polymerization method and encapsulated. Composite particles (hereinafter referred to as toner) A are included. The polymerization method is to obtain toner A through steps such as dispersion, polymerization, washing, solid-liquid separation, drying, classification, and surface treatment by adding raw materials, monomers, additives, and the like. The toner A is different from the conventional one in which the metal powder and the resin powder are simply kneaded, and the resin film R is uniformly formed around the metal powder C, and the particle diameter is almost uniform. The charge amount distribution can be made uniform. By dispersing the toner A in the solvent S, it is possible to obtain a wet developer that can form a dense circuit with extremely high resolution.
[0010]
In the present invention , the content ratio of the metal or metal oxide of the core / shell toner and the resin is 80:20 to 95: 5 wt%. Therefore, a high-quality circuit having a high metal content and low resistance can be formed.
As in the second aspect, it is desirable that the average particle diameter of the core / shell toner is 0.5 to 1.5 μm. In other words, the toner particle size is much smaller than the particle size (about 3 to 20 μm) of the charged powder for circuit formation contained in the conventional dry developer developer, so that the resolution is improved and the circuit line width is improved. Can be made ± 10 μm or less.
Thus, since the toner particle size is as small as about 1 μm and the toner specific charge is as large as about 10 times that in the dry method, the toner layer thickness is reduced and the conductor film thickness is also reduced as compared with the dry development method. Therefore, there is no step between the electrode portion and other portions, and a circuit pattern suitable for an electronic component obtained by laminating a large number of thin sheets like a multilayer ceramic capacitor can be formed.
[0011]
In the present invention, the viscosity of the solvent contained in the liquid toner, and a 15～20CSt. Generally, the viscosity (37.8 ° C.) of the solvent of the wet developer for OA is about 0.5 to 15 St. However, since the wet developer of the present invention contains metal or metal oxide particles, The mass per particle is larger than that of a wet developer. Therefore, by using a solvent having a high viscosity of 15 to 20 cSt, it is possible to prevent toner particles from settling and to perform good development.
Note that, if the viscosity of the solvent is increased, the movement of the toner in the solvent is hindered. Therefore, it is desirable to provide a developer stirring mechanism in the developing device. In addition, since the development time is insufficient, a plurality of developing devices may be provided for repeated development.
[0012]
In claim 3 , by forming a circuit by electrophotography using the wet developer according to claim 1 or 2 , it is possible to form a dense circuit pattern with high line width accuracy.
As the wet development method, a known development method such as a dish development method, a roller development method, or a flat development method may be used. Further, not only the direct development method but also an indirect development method (LTT) may be used.
According to claim 4, the material to be transferred in claim 3 and the ceramic green sheet, after fixing the circuit pattern image onto the transfer material, is intended to include a step of firing the ceramic green sheet. That is, since it does not have conductivity at the stage where the circuit pattern image is formed on the transfer object, the solvent and the resin film are decomposed and the conductor circuit is formed by baking this. Note that the firing atmosphere may be a reducing atmosphere or an oxidizing atmosphere depending on the metal material.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
The surface of Cu particles having an average particle diameter of 0.5 μm was coated with a polyethylene resin by a polymerization method to obtain resin-coated Cu particles (core / shell type toner) having an average particle diameter of 0.7 μm. These particles were mixed in an isoparaffin solvent (37.8 ° C. viscosity: 15 to 20 cSt) at a rate of 10 g of resin-coated Cu particles with respect to 100 ml of the solvent and dispersed over 5 hours to obtain a wet developer. . Using the obtained wet developer, a circuit pattern is formed by a wet development method (dish development method) on a ceramic green sheet made of a Ba-Si-Al-O-based ceramic and a binder, and fired in a reducing atmosphere at 960 ° C. As a result, a dense conductor film having a line width = 50 μm ± 3 μm and a Cu film thickness = 1.7 μm could be obtained. As a result of measuring the sheet resistance, it was 2.2 mΩ / □, and an extremely high quality circuit could be obtained.
[0014]
[Example 2]
The surface of the Ag particles having an average particle size of 0.3 μm was coated with a polyethylene resin by a polymerization method to obtain resin-coated Ag particles (core / shell type toner) having an average particle size of 0.5 μm. These particles were mixed in an isoparaffin-based solvent at a ratio of 10 g of resin-coated Ag particles to 100 ml of the solvent and dispersed for 8 hours to obtain a wet developer. Using the obtained wet developer, a circuit pattern was formed on a ceramic green sheet by a wet development method and baked in an oxidizing atmosphere at 900 ° C. As a result, line width = 75 μm ± 7 μm, Ag film thickness = 1.2 μm A dense conductor film was obtained.
[0015]
Example 3
In this embodiment, the insulating layer (ceramic layer) is transferred to a portion (negative portion) other than the circuit pattern of the ceramic green sheet (unfired) on which the circuit pattern is formed in Embodiment 1 or 2.
The surface of the ceramic powder having an average particle diameter of 0.8 μm was coated with a polyethylene resin by a polymerization method to obtain resin-coated ceramic particles (core / shell type toner) having an average particle diameter of 1.2 μm. These particles were mixed in an isoparaffin-based solvent at a rate of 10 g of resin-coated ceramic particles with respect to 100 ml of the solvent, and dispersed for 3 hours to obtain a wet developer. Using the obtained wet developer, a pattern was formed by electrophotography on a portion other than the electrode pattern of the ceramic green sheet on which the electrode pattern was already formed with the wet developer made of resin-coated Ni particles. A predetermined number of the ceramic green sheets thus obtained were laminated and then fired in an oxidizing atmosphere at 1200 ° C. to produce a multilayer ceramic capacitor. In this multilayer ceramic capacitor, since the ceramic film was formed with a thickness equivalent to the thickness of the electrode, there was no step between the electrode portion and the ceramic portion, and a multilayer ceramic capacitor that could be mounted satisfactorily was obtained.
[0016]
Example 4
In this example, a core / shell type toner in which metal oxide particles for circuit formation are used as a core and the surface of the core is coated with a thermoplastic resin by a polymerization method and encapsulated is used.
The surface of CuO particles having an average particle size of 0.7 μm was coated with a polyethylene resin by a polymerization method to obtain resin-coated CuO particles (core / shell type toner) having an average particle size of 0.9 μm. The content ratio between the metal oxide and the resin is 90:10 (wt%). The particles were mixed in an isoparaffin-based solvent at a ratio of 10 g of resin-coated CuO particles with respect to 100 ml of the solvent and dispersed for 5 hours to obtain a wet developer. Using the obtained wet developer, a circuit pattern was formed on a ceramic green sheet composed of a Ba-Si-Al-O-based ceramic and a binder by a wet development method and fired in a reducing atmosphere at 960 ° C. CuO as a product was reduced, and a dense conductor film with a line width = 75 μm ± 8 μm and a Cu film thickness = 1.5 μm could be obtained.
[0017]
Example 5
This example is also an example in which metal oxide particles for forming a circuit are used as a core as in Example 4.
The surface of Cu ₂ O particles having an average particle diameter of 0.8 μm was coated with a polyethylene resin by a polymerization method to obtain resin-coated Cu ₂ O particles (core / shell toner) having an average particle diameter of 1.2 μm. The content ratio of the metal oxide and the resin is 80:20 (wt%). These particles were mixed in an isoparaffin-based solvent at a ratio of 10 g of resin-coated Cu ₂ O particles with respect to 100 ml of the solvent and dispersed for 5 hours to obtain a wet developer. Using the obtained wet developer, a circuit pattern was formed on a ceramic green sheet composed of a Ba-Si-Al-O-based ceramic and a binder by a wet development method and fired in a reducing atmosphere at 960 ° C. Cu ₂ O as a product was reduced, and a dense conductor film with a line width = 75 μm ± 10 μm and a Cu film thickness = 1.3 μm could be obtained.
[0018]
In the wet development system as in the present invention, the toner particle size is small and the specific charge of the toner is large. Therefore, compared with the dry development method, the toner layer thickness is reduced and the conductor film thickness is also reduced. When a conductor with a high film thickness is required, multiple overprints may be performed. For this purpose, a plurality of photoconductors may be provided, or printing may be repeated by reciprocating the transfer object a plurality of times. Here, in the case where a plurality of photoconductors are provided and printing is repeated, it is more desirable if there is a mechanism for detecting the position of the transfer target supplied in advance and controlling the supply position.
[0019]
【The invention's effect】
As apparent from the above description, according to the present invention, a core / shell type toner in which metal or metal oxide particles are used as a core and the surface of the core is coated with a thermoplastic resin by a polymerization method is encapsulated. Since the wet developer is dispersed in a solvent, the toner particle size is smaller than that of a conventional dry developer, the line width accuracy of the obtained circuit is improved, and a dense circuit can be formed.
In addition, since the toner particles are encapsulated by coating the surface of a metal core with a thermoplastic resin by a polymerization method, the toner particles are compared with a toner made by kneading metal powder and resin powder like a conventional wet developer. Thus, a resin film can be uniformly formed around the metal powder, and the toner charge amount distribution can be made uniform. Therefore, there is an advantage that high resolving power can be obtained.
[Brief description of the drawings]
FIG. 1 is a view showing a state where core / shell type composite particles are dispersed in a solvent.
[Explanation of symbols]
A composite particles (toner particles)
C core R thermoplastic resin S solvent

Claims (4)

In a wet developer for forming a circuit for forming a circuit pattern on a transfer object by wet electrophotography,
The particles of metal or metal oxide as a core, the encapsulated core / shell type composite particles by coating the surface of the core thermoplastic resin in the polymerization process, it is dispersed in a solvent, the metal or metal oxide A wet developer for circuit formation , wherein the content ratio of the product to the resin is 80:20 to 95: 5 wt%, and the viscosity of the solvent is 15 to 20 cSt . 2. The wet developer for forming a circuit according to claim 1 , wherein the average particle size of the core / shell type composite particles is 0.5 to 1.5 μm. Forming a circuit pattern-like electrostatic latent image on the surface of the photoreceptor;
The step of developing the circuit-forming wet developer according to claim 1 or 2 with respect to the electrostatic latent image on the photoreceptor;
A step of transferring a circuit pattern image of the wet developer on the photoreceptor onto the transfer target;
And a step of fixing the circuit pattern image transferred onto the transfer medium. The transfer object is a ceramic green sheet,
4. The circuit forming method according to claim 3 , further comprising a step of firing the ceramic green sheet after fixing the circuit pattern image on the transfer target.

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