JP2001276645A - Chargeable powder for forming circuit and sorting method for the same - Google Patents

Abstract

(57) [Summary] [Problem] To prepare a resin-only powder mixed in a charged powder,
Easy and reliable selection from normal charged powder in which resin is bonded to conductive metal powder. The present invention is applied to a charged powder containing two or more kinds of powders having a difference of at least 1 g / cm ³ or more in average specific gravity. Charged powder is put into a liquid and stirred, and different kinds of powder are separated according to a difference in specific gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chargeable powder for forming a circuit, which is suitably used for forming a circuit pattern on an insulating substrate by electrophotography, and a method for selecting the same. The present invention relates to a technique for easily and surely selecting unnecessary powders contained therein.

[0002]

2. Description of the Related Art As a method of forming a circuit pattern on an insulating substrate, there has been a screen printing method using a printing paste containing a metal powder. However, in this method, a screen must be made for each circuit pattern, and in the case of a multi-layer circuit board, which is often produced in a small number of products, the number of types of screens increases, which is disadvantageous in terms of manufacturing efficiency and cost. However, there is a disadvantage that the screen must be re-produced even if the circuit pattern is partially changed, and a flexible response cannot be performed. Therefore, in recent years, an electrophotographic method of printing a charged powder on an insulating substrate by electrostatic force has been put to practical use.

The chargeable powder is mainly composed of a conductive metal powder and a heat-meltable resin, is mixed at a predetermined weight ratio, is hot-melt-kneaded with a kneader, and then is roughly pulverized by a cutter mill. The powder is manufactured by, for example, preparing a charged powder having an average particle diameter of 20 μm or less through pulverization by a jet mill, and then classifying the powder. In order to form a circuit pattern using the charged powder manufactured in this way, a circuit pattern is printed by an electrophotography method on a ceramic insulating substrate called a green sheet, which is baked and then baked. By burning the resin component and sintering the metal powders, a conductive metal circuit pattern is obtained.

In the case where the charged powder is manufactured as described above, even if the material is melted and kneaded with a kneader, the metal powder is difficult to be uniformly dispersed, and the powder of the resin to which the metal powder is not bonded is formed. Existed. In this state, a circuit pattern having a low resistance cannot be formed, and a circuit pattern that does not conduct may be formed in some cases. Therefore, it is necessary to remove powder of resin alone. The classifying step in the manufacturing process of the chargeable powder is to select a chargeable powder having a predetermined particle size and exclude a resin-only powder. As the classification method, an air flow method in which particles are selected using a difference in mass between particles is generally used.

[0005]

When the specific gravity of the charged powder and that of the resin are compared, the charged powder is larger than the resin, so that both have the same volume, or the volume of the charged powder particles is larger than the resin. In this case, the chargeable powder and the resin can be reliably separated. However, in the case where the volume of the resin is large and the difference in mass between the particles does not become remarkable, it is impossible in principle to select. For example, the specific gravity of the charged powder is 5 g /
cm ³ and the specific gravity of the resin is about 1 g / cm ³ , if the volume of the resin is about 5 times the volume of the charged powder,
The mass of the particles will be equal or close to it, making sorting impossible.

[0006] As described above, the air-flow classification method is not practical in some respects.
No. 237065 is proposed. In the sorting method, a charged first metal roller and a second metal roller to which a bias voltage having a polarity opposite to that of the first metal roller is applied are arranged close to each other, and charged powder is applied to the first metal roller. That is, only the charged powder is supplied to the second metal roller. However, this method has a disadvantage that if the powder of the resin alone has an electric charge, the resin is also mixed with the chargeable powder, so that the resin is not reliably sorted. Accordingly, an object of the present invention is to provide a method for selecting a chargeable powder for forming a circuit, which can easily and surely select a resin-only powder mixed in the chargeable powder.

[0007]

Means for Solving the Problems The chargeable powder for forming a circuit according to the present invention has an average specific gravity of 2 g / cm ³ or more.
Chargeable powder for circuit formation containing more than one kind of powder,
It is characterized in that it is obtained by pouring into a liquid and separating each powder by a difference in specific gravity.

The method for selecting a chargeable powder for forming a circuit according to the present invention is a method for selecting a chargeable powder for forming a circuit containing two or more kinds of powders having a difference of at least 1 g / cm ³ or more in average specific gravity. Wherein a chargeable powder is charged into a liquid to separate the two by a difference in specific gravity. According to the present invention, the respective powders introduced into the liquid are separated from each other in a vertical direction by a difference in specific gravity, so that each powder can be sorted by specific gravity. It is preferable to disperse the powder by stirring the liquid in addition to pouring the powder into the liquid, because the aggregation of the powder does not occur.

The powder of the present invention includes a normal chargeable powder (a conductive metal powder to which a heat-fusible resin is bonded) in a chargeable powder, and a heat-fusible resin powder (a conductive metal powder) in the chargeable powder. (Powder containing only resin not bonded to). Comparing the specific gravities of the two, the chargeable powder is larger than the resin powder, and the present invention is suitable for sorting those having a specific gravity difference of 1 g / cm ³ or more. That is, a chargeable powder in which a resin-only powder is mixed in a normal chargeable powder is charged into a liquid. Then, the resin-only powder floats above the charged powder, and separates from each other. Thereby, normal chargeable powder and resin-only powder can be sorted out. As a result, even if the mass of the particles is equal or the resin powder has a charge, without being affected by them,
The powder can be sorted out reliably.

In the present invention, it is preferable that two kinds of powders are used, and the specific gravity of the liquid used is larger than the specific gravity of the powder having the smaller specific gravity. For example, the specific gravity of a normal charged powder is at least 3.4 g / cm ³ ,
When the specific gravity of the resin-only powder is at most 1.3 g / cm ³ , a liquid having a specific gravity of 1.4 g / cm ³ or more is used. Then, the resin powder having a lower specific gravity than the liquid floats on the liquid surface, and the charged powder exists in the liquid. In this way, the two are separated, so that the sorting becomes easy. In this embodiment, if a liquid having a specific gravity indicating the middle of two kinds of powders is used,
The powder having a small specific gravity floats on the liquid surface, and the powder having a large specific gravity settles.

As the liquid used in the present invention, a liquid having a specific gravity capable of selecting each powder based on a specific gravity difference is appropriately selected. In the case of applying the above-mentioned chargeable powder sorting, the specific gravity of the chargeable powder is generally about 5 g / cm ³ ,
Since the resin powder is 1 g / cm ³ , 2 to ³ g / cm ³
A liquid having a specific gravity of the order is preferably used. Specifically, a liquid based on a halogenated hydrocarbon, a fluorine compound, or the like can be used, but a liquid based on a fluorine compound is preferable from the viewpoint of safety. Examples of the fluorine compound include dodecafluorocyclohexane, perfluoroalkane, perfluorotrialkylamine, perfluoropolyethers, and pentafluorodichloropropane. Liquids, for example, do not melt the resin,
Those that do not attack the components constituting the charged powder are selected. The lower the viscosity of the liquid, the better the separation of the powder to be sorted out.

Here, a conductive metal powder and a hot-melt resin which are preferably used as the material of the chargeable powder for forming a circuit of the present invention are listed. As the conductive metal powder, a known metal material for forming a circuit, such as copper, nickel, silver, and palladium, which is used alone or an alloy thereof is used. The average particle size of the conductive metal powder is desirably 1 μm or more in order to prevent ground fog, and desirably 20 μm or less in order to form a precise circuit pattern.

Examples of the heat-fusible resin include homopolymers of styrene and substituted styrenes such as polystyrene, poly p-chlorostyrene, polyvinyl toluene, styrene-p-chlorostyrene copolymer and styrene-vinyl toluene copolymer. Copolymers of styrene and acrylate, such as copolymers thereof, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-n-butyl acrylate copolymer, styrene-methacrylic Copolymers of styrene and methacrylate, such as methyl acrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-n-butyl methacrylate copolymer, and multi-components of styrene, acrylate and methacrylate Copolymer, other styrene-acrylonitrile copolymer, styrene Styrene-based copolymers of styrene with other vinyl-based monomers, such as nylmethyl ether copolymer, styrene-butadiene copolymer, styrene-vinyl methyl ketone copolymer, styrene-maleic acid ester copolymer, polymethyl Methacrylate, polybutyl methacrylate, polyester resin, epoxy resin, etc. alone,
Alternatively, they are used in combination.

Further, the chargeable powder for forming a circuit of the present invention may contain a charge controlling agent for imparting polarity, an external additive for imparting fluidity, and the like. Examples of the charge control agent include a nigrosine dye, a quaternary ammonium salt, a pyridinium salt, azine, an azo-based metal-containing complex, and a salicylic acid-based metal complex. In addition, examples of the external additive include hydrophobic silica.

The chargeable powder for forming a circuit according to the present invention is obtained by dispersing the conductive powder, a charge control agent, an external additive and the like in the hot-melt resin. Further, the surface of the conductive metal powder may be coated with a hot-melt resin in which a charge control agent, an external additive, and the like are dispersed, and then the external additive may be attached.
In addition, the surface of the conductive metal powder is coated with a hot-melt resin,
Further, a charge control agent, an external additive, or the like may be attached or fixed to the surface of the coated hot-melt resin.

As a method for coating the surface of the conductive metal powder with a hot-melt resin, there are a capsule method in which the surface of the conductive metal powder is polymerized and coated with a resin monomer, and a method in which the surface of the conductive metal powder is coated with a resin. After the particles are adhered, a method of fixing the resin particles to the surface of the conductive metal powder by a mechanical method and coating the particles with the resin particles can be used.

Specific examples of the machine used in the above-mentioned mechanical method include a hybridization system manufactured by Nara Machinery Co., Ltd., a mechanofusion system manufactured by Hosokawa Micron, and an angmill manufactured by Hosokawa Micron.
As a method for attaching or fixing a charge control agent, an external additive, and the like to the surface of the heat-meltable resin coated on the surface of the conductive metal powder, general methods such as a turbine-type stirrer, a Henschel mixer, and a super mixer are used. Or a mechanical stirrer.

[0018]

Next, an embodiment of the present invention will be described. Example 1 A spherical copper powder having an average particle diameter of 6.1 μm, a styrene acrylic resin (specific gravity: 1.1 g / cm ³ ), and a charge controlling agent (azo metal complex) were mixed at 80: 20: 0. The resulting mixture was mixed at a weight ratio of 1 and mixed with a super mixer, followed by hot melt kneading with a kneader. Next, the kneaded material was coarsely pulverized by a cutter mill and further finely pulverized by a jet mill to obtain a charged powder having an average particle diameter of 7.3 μm. The specific gravity of the charged powder was 3.7 g / cm ³ . Also,
When the charged powder was examined, it was confirmed that the resin powder that was not bonded to the charged powder was mixed. Next, this chargeable powder was prepared to have a specific gravity of 1.94 g / c.
m ³ was poured into a perfluorotripentylamine solution and stirred. As a result, the normal charged powder to which the resin was bound settled, while the resin-only powder floated to the liquid surface. In this way, normal chargeable powder and resin-only powder could be selected.

Next, the normal charged powder precipitated in the perfluorotripentylamine solution is taken out, washed and dried, and the charged powder and a ferrite carrier having an average particle size of 60 μm are mixed at a weight ratio of 85:15. To form a two-component developer (toner). Next, the latent image of an arbitrary circuit pattern formed on the photoreceptor is developed by a dry two-component developing method, and is formed by a slurry in which a Ba-Al-Si-O-based ceramic powder and a binder are dispersed in a solvent. After electrostatic transfer onto a ceramic green sheet having a thickness of 100 μm, the resultant was thermally fixed to form a circuit pattern using a toner layer.

Next, the ceramic green sheet was heated to 1000 ° C. in a reducing atmosphere to decompose the resin in the toner and the binder in the ceramic green sheet, and then sintered the ceramic substrate and the circuit pattern to obtain a conductive circuit. .

Example 2 Copper powder and styrene acrylic resin particles used in Example 1 (specific gravity: 1.1 g / cm ³ )
And a charge controlling agent (azo-based metal complex) at 90:10:
The mixture was stirred at a weight ratio of 0.1 using a hybridization system manufactured by Nara Machinery Co., Ltd. to obtain a charged powder. The specific gravity of this charged powder was 4.4 g / cm ³ . Further, when the charged powder was examined, it was confirmed that powder of only the resin that did not bind to the charged powder was mixed. Next, this charged powder was charged into a perfluorotributylamine liquid having a specific gravity of 1.88 g / cm ³ and stirred. As a result, the normal charged powder to which the resin was bound settled, while the resin-only powder floated to the liquid surface. In this way, normal chargeable powder and resin-only powder could be selected. Next, a conductor circuit was obtained in the same manner as in Example 1 except that the selected normal chargeable powder was used.

Comparative Example 1 A conductor circuit was obtained in the same manner as in Example 1 except that the pre-sorted chargeable powder resin obtained in Example 1 was used. Comparative Example 2 A conductor circuit was obtained in the same manner as in Example 1 except that the pre-sorted chargeable powder resin obtained in Example 2 was used.

Subsequently, Examples 1 and 2 and Comparative Examples 1 and 2
The electric resistance of the conductor circuit was measured. Table 1 shows the results together with the manufacturing conditions. As is clear from Table 1, the conductor circuits using the charged powders of Comparative Examples 1 and 2 had high electric resistance and sometimes did not conduct. On the other hand, the electric resistance of the conductor circuit obtained by the chargeable powder having undergone the sorting step according to the example of the present invention was relatively low, and the effect of the present invention was confirmed.

[0024]

[Table 1]

[0025]

As described above, according to the present invention,
A chargeable powder for circuit formation is charged into a liquid, and different kinds of powder are separated in the liquid by the difference in specific gravity.This is a chargeable powder for circuit formation, so that a circuit with low electric resistance and good conductivity is formed. be able to. Further, according to the sorting method of the present invention, the chargeable powder for forming a circuit is put into a liquid, and different kinds of powders are separated and separated by a specific gravity difference in the liquid, so that the powder can be easily and reliably sorted. Can be.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/09 H01L 23/14 Z (72) Inventor Kamada Akihiko 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto 2H005 AA29 AB03 CB06 EA10 4D071 AA44 AB04 AB15 AB23 BA05 BA13 BB13 DA20 4E351 AA07 BB01 BB29 CC16 CC22 CC31 DD04 DD05 DD19 DD20 DD21 DD52 EE02 EE03 GG06

Claims (5)

[Claims] 1. A chargeable circuit-forming powder containing two or more kinds of powders having a difference of 1 g / cm ³ or more in average specific gravity is charged into a liquid, and each powder is separated by a specific gravity difference. A chargeable powder for forming a circuit, characterized by being obtained. 2. The chargeable powder for forming a circuit according to claim 1, wherein the two or more kinds of powders are a normal chargeable powder and a hot-melt resin powder. 3. A method for selecting a chargeable powder for forming a circuit containing two or more kinds of powders having a difference of at least 1 g / cm ³ or more in average specific gravity, comprising charging the chargeable powder into a liquid, A method for selecting a chargeable powder for forming a circuit, wherein each powder is separated by a specific gravity difference. 4. The method for selecting a chargeable powder for forming a circuit according to claim 3, wherein the two or more kinds of powders are a normal chargeable powder and a hot-melt resin powder. 5. The method according to claim 3, wherein the powder is of two types, and the specific gravity of the liquid is greater than the specific gravity of the powder having a small specific gravity.