JP3512620B2 - Method of forming conductor pattern - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a conductor pattern on a ceramic green sheet using insulated surface-treated metal particles obtained by surface-treating and insulating metal particles.

[0002]

2. Description of the Related Art Conventionally, in the formation of a conductor pattern such as an electrode of a ceramic multilayer capacitor or the like, a metal such as copper or tungsten is placed on a thin green sheet made of ceramic powder such as silica / alumina and an organic binder. An electrode pattern was formed by forming a paste of particles in a pattern by screen printing and firing the paste.
However, since this method uses a screen composed of a mesh net, the printing accuracy decreases due to screen sagging after endurance, material loss for creating the screen for each pattern, and material loss that adheres to the mesh. There was a problem of causing.

In order to solve the above-mentioned drawbacks, JP-A-59-59
No. 189617, No. 59-202682, No. 60-137886, No. 60-160690 and the like describe that an electrode pattern of conductive particles is formed by an electrophotographic method, and the pattern is baked. There is.
Specifically, for example, tungsten powder and styrene acrylic resin are kneaded, pulverized, and classified to obtain particles for printing (toner) having a particle size of 10 to 20 μm. An electrode pattern is formed. However, since the printing particles in these methods have low resistance and easily leak electric charges, it has been difficult to reproduce a highly accurate pattern in an electrophotographic apparatus, and it is difficult to form a reliable conductive path.

[0004]

In the above-mentioned conventional printing particles, the composition of the particles has not yet formed high resistance particles, and the charging becomes non-uniform. That is, when a sufficient amount of metal powder to form a conductive path after firing is mixed in the particles, the amount of resin is relatively decreased, the amount of metal powder exposed on the surface of the particles is increased, and the resistance of the particles is lowered. On the other hand, when the amount of resin is increased to increase the resistance, the amount of metal particles is decreased, and it becomes difficult to create the conductive path, which is the original purpose. Therefore, in the conventional method using printing particles, it is difficult to form an image by the electrophotographic method in which the particles are controlled as charged particles. Therefore, it is an object of the present invention to form a conductor pattern with higher accuracy and higher reliability as compared with a system using a conventional electrophotographic method.

[0005]

According to the method of forming a conductor pattern of the present invention, the surface of metal particles is covered with a thermoplastic insulator to be insulated, and the insulated surface has an average particle diameter of 2 to 20 μm. Using a one-component developer composed of treated metal particles, a thin layer of the one-component developer is brought into contact with the photoconductor to form a visible image of the insulated surface-treated metal particles on the photoconductor by electrophotography. , A ceramic thin film green sheet composed of a dielectric powder and an organic binder. The insulated surface-treated metal particles used in the present invention can enclose a large amount of metal particles, and since the surface is firmly covered with the thermoplastic resin, the particles are insulators and are stably and uniformly charged. There is no charge leakage. Therefore, it can be suitably used as a toner in a developer for electrophotography, and is suitable for printing a conductor pattern on a ceramic green sheet.

Further, the amount of the thermoplastic insulator in the insulated surface-treated metal particles is set to 20% by weight or less, and the particle size distribution of the particles is 90% or more in volume ratio within the range of the average particle size ± 40%. By doing so, a good print pattern can be obtained. As the metal particles, conductive particles such as copper, tungsten, nickel and silver can be used. developing·
In the printing system, the amorphous silicon type photoconductor can be preferably used. Further, it is preferable to set the gap between the photoconductor, which is the electrostatic latent image carrier, and the developing roller, which is the developer carrier, that is, the nip width to 1 to 4 mm. Further, the layer thickness (adhesion amount) of the insulating surface-treated metal particles (one-component developer) on the surface of the developer carrier is 1
It is desirable to set it to 0 to 50 μm and to set the linear velocity ratio of the developer carrying member to the photosensitive member to 1.2 to 5.0 times.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The insulated surface-treated metal particles used in the present invention are formed by coating the surfaces of the metal particles with a thermoplastic insulator. As the metal particles, any may be used,
From the viewpoint of printing a conductor pattern on a ceramic green sheet, copper, tungsten, nickel, silver or the like is used. The selection of the metal is determined by the conditions such as the firing temperature. For example, when the inorganic material used for the green sheet is silica, copper is suitable as the conductive metal, and when it is alumina, tungsten is suitable. Various synthetic resins are used as the thermoplastic insulator. Since the conductor pattern is printed on the ceramic green sheet, it is necessary to eliminate the conductor pattern when firing the ceramic green sheet, and a polyolefin resin such as polyethylene is preferable.

The method of coating the surface of the metal particles is not particularly limited, but it is desirable to completely coat the surface of the metal particles without substantially exposing the surface of the metal particles, and this method can be realized with a small amount of thermoplastic insulator. Is preferred. As this method, for example, there is a method in which a monomer is directly polymerized on the surface of metal particles to form a thermoplastic resin layer. Specifically, for example, a catalyst is adsorbed on the surface of metal particles, ethylene gas or the like is supplied, and this monomer gas is directly polymerized on the surface of the metal particles to form a polyethylene resin film. Although this method is a method for producing carrier particles, it is disclosed in JP-A 2-1.
It is described in detail in No. 87770, No. 2-187771, etc., and can be directly applied to the production of the insulated surface-treated metal particles of the present invention.

In the present invention, the insulating surface-treated metal particles have an average particle size of 2 to 20 μm, preferably 3 to 10 μm. If this average particle size is too large or too small, electrostatic control becomes difficult, and fog on the ground occurs and the image level decreases. If the average particle size is large, fine pattern printing cannot be performed. Further, the particle size distribution of the insulating surface-treated metal particles is important. If the particle size distribution is too wide, large particles and small particles remain undeveloped, resulting in a difference in charged state between the remaining particles and particles newly added and mixed, which causes fog. Furthermore, it is difficult to reproduce a fine pattern with the insulating surface-treated metal particles having a large particle diameter. By setting the particle size distribution of the insulated surface-treated metal particles so that 90% or more by volume ratio is distributed within the range of ± 40% of the average particle size, fog does not occur even when printing 30,000 sheets. It was confirmed.

The insulated surface-treated metal particles used in the present invention are used as a one-component electrophotographic developer. In the electrophotographic method, the toner is mainly controlled by electrostatic force, so that it is required to be stably and uniformly charged. Therefore, the insulated surface-treated metal particles of the present invention are required to be an insulator, which is achieved by covering the surfaces of the metal particles with an insulator.

The insulated surface-treated metal particles have a resistance value of 10 ¹²
It is preferably Ω · cm or more, and more preferably 10 ¹³ Ω · cm or more. If the particle resistance value is less than 10 ¹² Ω, background fog and transfer failure are likely to occur. Also,
In order to increase the insulating property, it is conceivable to increase the total amount of the insulating material, but if the amount is increased too much, the amount of the conductive material after firing will decrease, and it will be difficult to obtain continuity of the conductive pattern. Generally, the thickness of the conductive path on the pattern needs to be 20 μm or more. Considering the difference in specific gravity between the metal and the insulating material, the packing rate of particles on the sheet after transfer, the amount of particles that can be controlled by an electrophotographic technique, etc. The amount of the insulating material in the insulated surface-treated metal particles is preferably 20% by weight or less, more preferably 15% by weight or less.

In the developer of the present invention, a fluidity imparting agent, an abrasive, a lubricant,
The charge control particles and the like can be added alone or in combination.

FIG. 1 shows an electrophotographic apparatus used in the present invention, which is no different from a general apparatus. That is, the drum-shaped photosensitive member 11 of amorphous silicon type or the like
The charging member 13, the image signal exposing member 15, the developing member 17, the transfer member 19, and the cleaning blade 2 around the
1. The whole surface exposure member 23 is provided. By using an amorphous silicon-based photoconductor with excellent printing durability,
An apparatus is provided that facilitates maintenance and reduces material loss. In the present invention, the one-component developer containing the insulated surface-treated metal particles of the present invention as a toner is supplied to the developing member 17. An electrostatic latent image of a conductor pattern is formed by the image signal exposure member 15 on the photoconductor 11 uniformly charged in the dark by the charging member 13, and this is the developing member 17.
To form a toner image (visual image) on the surface of the photoconductor 11 by contact development with the insulating surface-treated metal particles.

As a method for developing an electrostatic latent image using insulated surface-treated metal particles which is a one-component developer of the present invention, contact development is suitable because the particles are large in weight. In particular, a method in which a developing roll made of an elastic material such as a rubber material is used as a developer carrying member, and particles are attached to the surface of the developing roll to bring them into contact with each other at a nip width and a linear velocity ratio, has good pattern reproducibility, This is a suitable method because the thickness can be made large. It is preferable that the nip width, that is, the gap between the drum-shaped photosensitive member which is the electrostatic latent image carrier and the developing roller which is the developer carrier is set in the range of 1 to 4 mm.
The nip width is preferably 1 mm or more in order to obtain the developing time and distance, and is preferably larger, but if it is 4 mm or more, the elastic material of the developing roll needs to be over-compressed, and the particles are crushed to cause a characteristic change. Cheap. It is also possible to increase the diameters of the electrostatic latent image bearing member and the developer bearing member, but the distance before and after the nip becomes too short, discharge easily occurs, and potential change of the latent image easily occurs, causing fog. .

The adhesion amount of the insulating surface-treated metal particles on the surface of the developer carrier should be adjusted to optimize the thickness after development.
It is set to 10 to 50 μm in order to accurately control the charge amount of particles and prevent scattering from the surface. In order to efficiently develop this amount of particles, the linear velocity of the developer carrying member with respect to the electrostatic latent image carrying member is preferably 1.2 to 5.0 times. This linear velocity is less than 1.2 times, especially when there is no linear velocity ratio (when 1.0 times)
Fogging is likely to occur, and if it exceeds 5.0 times, scattering or fogging is likely to occur.

Next, a thin sheet (green sheet) made of ceramic powder such as silica and alumina and an organic binder is supplied between the photoreceptor 11 and the transfer member 19, and a toner image is formed on the ceramic green sheet. Is transcribed. In the present invention, the insulating surface-treated metal particles used as the toner have high resistance and can be uniformly and stably charged, so that the development process and the transfer process can be easily controlled, and a highly accurate pattern can be formed on the green sheet. printing,
Can be formed. The members around the photoconductor 11 in FIG. 1 can be changed in various ways. For example, as the charging member 13, a conductive brush or a conductive roller can be used instead of the corona charging device.

The green sheet on which the pattern is formed is
A conductor pattern is obtained by heating at an appropriate temperature, for example, 800 ° C. or higher and firing to eliminate the insulator. The insulated surface-treated metal particles of the present invention have a high resistance value and can be uniformly charged, but since the metal particles occupy many portions,
After firing, a conductive pattern having good continuity and high reliability can be obtained. In the present invention, as the ceramic thin film green sheet, a green sheet made of a dielectric powder such as silica or alumina and an organic binder is used. The amount of the organic binder in the green sheet is appropriately in the range of 10 to 40% by weight considering that it will disappear during high temperature firing. When the amount of the organic binder is too large, the expansion and contraction of the sheet before and after firing are large, and the product variation increases. Further, the amount of the organic binder is preferably 50 to 400% with respect to the amount of the insulator in the insulated surface-treated metal particles, and preferably 50.
~ 200%. Within this range, it is possible to suppress deformation of the pattern due to expansion and contraction of the sheet, and to stably form the pattern after firing.

In addition, until the final conductor pattern is formed by firing in a reducing furnace in a firing furnace after transfer, a pattern image made of insulated surface-treated metal particles is fixed and temporarily attached on the green sheet. It is preferable to fix it. As a result, handling between the electrophotographic image forming apparatus and the firing furnace is facilitated, and efficient firing and formation of a conductor pattern are performed. For this, the following methods are available, for example. (1) Utilizing that the insulator of the insulating surface-treated metal particles is a thermoplastic resin such as a polyolefin resin, the insulator is softened by heating and fixed to the green sheet. In order to fix the pattern without changing the organic binder of the green sheet, it depends on the material selection, but if you consider polyvinyl butyral, acrylic resin, etc., which are the binder resins currently used for general sheet materials, 200 ° C or less Is appropriate.

(2) Pressure is applied to the green sheet to fix the insulated surface-treated metal particles to the green sheet. Similar to the above, the pressure is 60k from the viewpoint of transformation prevention.
It is preferably g · f / cm or less. (3) An adhesive is sprayed to fix the insulated surface-treated metal particles on the green sheet. As the pressure-sensitive adhesive, a commercially available varnish sprayer (mainly acrylic resin) may be used.

[0020]

According to the electrophotographic image forming method of the present invention, by using the insulating surface-treated metal particles having both a large metal particle ratio and a high insulating property, it is possible to uniformly charge due to the high insulating property. As a result, a conductor pattern can be printed and formed on the green sheet with high accuracy, and a conductor pattern having good continuity and high reliability after firing can be formed.

[0021]

EXAMPLE Using the electrophotographic image forming apparatus shown in FIG.
A conductor pattern was printed on the ceramic green sheet. Here, as the photosensitive member, an amorphous silicon photosensitive member having a photosensitive layer thickness of 25 μm was used. As the insulating surface-treated metal particles used as a toner, an ethylene monomer is directly polymerized on copper powder, and the copper powder is coated with polyethylene resin in an amount of 6% by weight. Toner particles to which 1.0% and silica 1.0% were externally added were used. An image of a conductor pattern was formed using the toner as a developer. The image forming conditions were set as follows. Photoconductor charge potential: 350V After exposure After exposure: 15V Current image potential: 120V Photoconductor drum linear velocity: 60mm / sec Development roller linear velocity: 90mm / sec

By electrophotography, 70% by weight of SiO ₂ ,
After forming a conductor pattern on a green sheet made of 30% by weight of an acrylic resin, it was put on a hot plate kept at 180 ° C. for 2 minutes and put on. Then this is 90
The conductor pattern made of copper was formed on the ceramic substrate by sintering in a reducing atmosphere at 0 ° C. for 1 hour. Under the above conditions, the following experiments were conducted as a base to confirm the influence of each condition parameter. As shown in Table 1, a good printed pattern was obtained with a particle size of 2 to 20 μm. As shown in Table 2, when the amount of the insulating material was 20% or less by weight, stable conduction after firing was obtained. Table 3
As described above, when the volume ratio of the particles was 90% or more in the range of the average particle diameter ± 40%, fog was not generated up to 30,000, and a good print pattern was obtained. As shown in Table 4, a good print pattern was obtained when the width of the developing nip was 1 mm or more and 4 mm or less. As shown in Table 5, the particle layer thickness is 10 to 50 μm.
m, a good print pattern was obtained when the linear velocity ratio was 1.2 times or more and 5.0 times or less.

[0023]

[Table 1] Table 1: Relationship between particle size of metal particles in developer and image characteristics Metal particle size (μm) Image characteristics 1.0 Fog generation 2.0 ○ 3.0 ○ 4.0 ○ 6.0 ○ 15.0 ○ 18.0 ○ 20.0 ○ 22.0 Fog occurred 25.0 Fog occurred, fine line not reproduced

[0024]

[Table 2] Table 2: Insulator content rate in metal particles Insulator content rate (%) Pattern specific resistance (Ω · cm) 4 3.0 × 10 ⁻⁶ (with continuity) 8 1.7 × 10 ⁻⁶ (Conducted) 15 3.4 × 10 ^-6 (Conducted) 20 1.7 × 10 ^-4 (Conducted) 25 3.0 × 10 ⁶ (No conduction)

[0025]

[Table 3] Table 3: Image characteristics based on the average particle size and particle size distribution of metal particles covered with an insulating material Average particle size (μm) Particle size distribution (range in which 90% is distributed) Image property 4.0 Average particle size ± 30% 30,000 good images 6.0 Average particle size ± 30% 30,000 good images 6.0 Average particle size ± 40% 30,000 good images 6.0 Average particle size ± 50% Fog at 5,000 sheets 9.0 Average particle size ± 30% 30,000 Good image 9.0 Average grain size ± 40% 30,000 sheets Good image 9.0 Average grain size ± 50% Fog occurred at 4,000 sheets

[0026]

[Table 4] Table 4: Image characteristics depending on the width of the development nip Development nip width (mm) Image characteristics 0.5 Low density (photoconductor diameter 30 mm, developing roll diameter 18 m) 1.0 Good (photoconductor diameter 30 mm, developing roll diameter 18 m) 1.5 Good (photoconductor diameter 30 mm, developing roll diameter 18 m) 2.0 Good (photoconductor diameter 30 mm, developing roll diameter 18 m) 3.0 Good (photoconductor diameter 30 mm, developing roll diameter 18 m) 4.0 Good (photoconductor diameter 30 mm, developing roll diameter 18 m) ) 4.0 Good (photoconductor diameter 60 mm, developing roll diameter 18 m) 5.0 Fogging (photoconductor diameter 30 mm, developing roll diameter 40 m) 5.0 Fogging (photoconductor diameter 60 mm, developing roll diameter 40 m)

[0027]

[Table 5] Table 5: Image characteristics according to particle supply amount Linear velocity ratio of developing roller to photoconductor Particle thickness layer (μm) 1.0 times 1.2 times 1.5 times 2.5 times 5.0 times 7.5 times 5.0 × △ △ ○ ○ ○ 10.0 × ○ ○ ○ ○ ○ 20.0 × ○ ○ ○ ○ ○ 30.0 × ○ ○ ○ ○ × 40.0 × ○ ○ ○ ○ × 50.0 × ○ ○ ○ ○ × 60.0 × ○ × × × ×

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an electrophotographic image forming apparatus used in the present invention.

[Explanation of symbols] 11 photoconductor 13 Charging member 15 Image signal exposure member 17 Developing member 19 Transfer member 21 cleaning blade 23 Full surface exposure member

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-61-78114 (JP, A) JP-A-59-189617 (JP, A) JP-A-62-168175 (JP, A) Sankaihei 2- 107162 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01G 4/00-17/00

Claims (8)

(57) [Claims] 1. A one-component developer comprising an insulated surface-treated metal particle having an average particle size in the range of 2 to 20 μm, in which the surface of the metal particle is covered with a thermoplastic insulator to be insulated, and one component is used. By bringing a thin layer of developer into contact with the photoconductor, an electrophotographic image is formed on the photoconductor to form a visible image of insulated surface-treated metal particles, and a ceramic thin film green comprising a dielectric powder and an organic binder. A method for forming a conductor pattern, which comprises transferring to a sheet. 2. The amount of the thermoplastic insulating material in the insulated surface-treated metal particles is 20% by weight or less, and the particle size distribution of the insulated surface-treated metal particles is within a range of average particle diameter ± 40% by volume ratio. The method for forming a conductor pattern according to claim 1, wherein 90% or more is distributed. 3. The insulated surface-treated metal particles, wherein the surface of the metal particles is directly polymerized with a monomer to form a coating made of a thermoplastic insulating material on the surface of the metal particles, and the coated surface-treated metal particles are used.
Alternatively, the method of forming a conductor pattern according to Item 2. 4. The method for forming a conductor pattern according to claim 1, wherein copper, tungsten, nickel or silver is used as the metal particles. 5. The method for forming a conductor pattern according to claim 1, wherein the nip width between the developer bearing member and the photosensitive member surface is set to 1 to 4 mm. 6. The adhesion layer thickness of the insulating surface-treated metal particles in the developer carrier is set to 10 to 50 μm, and the linear velocity ratio of the developer carrier to the photoconductor is 1.2 to 5.0 times. The method for forming a conductor pattern according to any one of claims 1 to 5, wherein the conductor pattern is formed. 7. The method for forming a conductor pattern according to claim 1, wherein an amorphous silicon-based photoconductor is used as the photoconductor. 8. The ceramic according to any one of claims 1 to 7, wherein a conductor pattern made of a bonded body of metal particles is formed on the ceramic substrate after transferring onto a green sheet and then firing. A method for forming a conductor pattern on a substrate.