JPH11340607A - Method for forming circuit and multilayer wiring substrate formed there by - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a circuit, whereby a highly accurate circuit pattern can be formed on a printed material, and a multilayer wiring substrate formed by the method. SOLUTION: In a first step (a), circuit forming patterns 12 are formed by an adhesive resin containing no metal on a ceramic green sheet 11. Next, in a second step (b), copper powder 13 is dispersed on the heated ceramic green sheet 11, and the copper powder 13 is stuck to the melted circuit forming patterns 12. Then, in a third step (c), unwanted copper powder 13a of the copper powder 13, that is not adhered to the circuit forming patterns 12 on the ceramic green sheet 11, is removed. Finally, in a fourth step (d), the copper powder 13, which is stuck to the circuit forming patterns 12 on the ceramic green sheet 11, is fixed by a flash lamp to form a circuit pattern.

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 circuit pattern and a multilayer wiring board formed thereby, and more particularly to a method for forming a circuit pattern on a substrate by electrophotography and a method for forming the circuit pattern. To a multilayer wiring board.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a circuit pattern on a ceramic green sheet constituting a multilayer wiring board, terpineol is prepared by mixing a metal powder such as silver, platinum, copper and palladium with a binder such as ethyl cellulose. A method of forming a paste by adjusting the viscosity with a solvent such as tetralin, butyl carbitol or the like, and forming a predetermined circuit pattern on a ceramic green sheet by screen printing using the paste has been widely put to practical use. However, in this screen printing method, it is necessary to prepare a dedicated mask corresponding to each circuit pattern, especially in the case of a multi-layer wiring board, which tends to be produced in many kinds and small quantities,
There are problems in that the number of types of dedicated masks increases, the time for creating the dedicated masks increases, and the manufacturing cost of the multilayer wiring board increases. Also, even if the circuit pattern is partially changed, the dedicated mask must be recreated,
There is also a problem that flexible responses cannot be taken.

[0003] In order to solve such problems of the screen printing method, a method of printing a circuit pattern on a ceramic green sheet by electrophotography has recently been developed. In this method of forming a circuit pattern by electrophotography, a chargeable powder for circuit formation is adhered on a latent image pattern formed on a photoreceptor by electrostatic force, and the latent image pattern is developed with the chargeable powder for circuit formation. The circuit pattern is obtained by transferring the chargeable powder for circuit formation on the latent image pattern to the ceramic green sheet. The chargeable powder for forming a circuit used in the electrophotography is obtained by mixing a metal, a charge control agent, a hot-melt resin, and the like, melting and kneading the mixture, and coarsely and finely pulverized and classified. Can be

[0004]

However, in the conventional method of forming a circuit pattern by electrophotography, since the chargeable powder for forming a circuit contains a metal, it is extremely difficult to control the charge of the chargeable powder for forming a circuit. It is difficult to form a high-precision circuit pattern, the film thickness required to function as a circuit pattern cannot be obtained,
Problems such as difficulty in producing a stable and inexpensive chargeable powder for forming a circuit due to abrasion of a pulverizer and a classifier used for manufacturing the chargeable powder for forming a circuit occur.

The present invention has been made to solve such a problem, and a circuit pattern forming method and a circuit pattern forming method capable of forming a high-precision circuit pattern on a print substrate. An object is to provide a multilayer wiring board.

[0006]

In order to solve the above-mentioned problems, a circuit pattern forming method of the present invention is a circuit pattern forming method for forming a circuit pattern on a printing substrate, wherein an adhesive resin is formed on the printing substrate. A first step of forming a circuit-forming pattern by spraying a metal or metal oxide on the heated printing substrate, and attaching the metal or the metal oxide to the circuit-forming pattern.
And removing the unnecessary metal or metal oxide not adhering to the circuit forming pattern on the printing object from the printing medium, of the metal or the metal oxide, And a third step of forming the circuit pattern.

Also, there is provided a circuit pattern forming method for forming a circuit pattern on a printing substrate, comprising: a first step of forming a circuit forming pattern on the printing substrate with an adhesive resin; A second step of spraying a metal or a metal oxide and adhering the metal or the metal oxide to the circuit forming pattern; A third step of removing unnecessary metal or metal oxide not adhering to the pattern from the substrate, and forming the circuit pattern on the substrate; and forming the circuit pattern on the substrate. A fourth step of fixing the metal or the metal oxide by heat roller fixing.

Further, in the first step, a charge control agent is contained in the adhesive resin, and the circuit forming pattern is formed on the printing material by electrophotography.

In the multilayer wiring board according to the present invention, the printed material is a ceramic green sheet, and the ceramic green sheet on which the circuit pattern is formed is laminated and fired by the circuit pattern forming method described above. It is characterized by.

According to the circuit pattern forming method of the present invention,
Since the method includes the third step of removing unnecessary metal or metal oxide that is not attached to the circuit forming pattern on the substrate from the substrate, it is possible to collect all unnecessary metal or metal oxide. it can.

According to the multilayer wiring board of the present invention, a circuit pattern forming step including a step of removing unnecessary metal or metal oxide other than the circuit forming pattern from the ceramic green sheet is performed on the ceramic green sheet. Since a circuit pattern is formed, and then the ceramic green sheets are laminated and formed by a normal manufacturing method, it is possible to prevent short circuit of the circuit pattern constituting the multilayer wiring board after firing.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a process chart of an embodiment of a circuit pattern forming method according to the present invention. First, as shown in FIG. 1A, in a first step, a circuit forming pattern 12 is formed on a ceramic green sheet 11, which is a printing substrate, with an adhesive resin containing no metal.

Next, as shown in FIG. 1 (b), in a second step, a copper powder 13 as a metal is sprayed on the ceramic green sheet 11 heated by an oven or the like, and the ceramic green sheet melted by heating. A copper powder 13 is adhered to a circuit forming pattern 12 on 11. On this occasion,
Since the circuit forming pattern 12 made of the adhesive resin acts as an adhesive, the copper powder 13 adheres only to the circuit forming pattern 12 on the ceramic green sheet 11 by cooling the ceramic green sheet 11.

Then, as shown in FIG. 1C, in a third step, the ceramic green sheet 11 is vibrated with the side on which the circuit forming pattern 12 is formed facing downward, so that the copper is vibrated. Circuit forming pattern 1 of ceramic green sheet 11 of powder 13
Unnecessary copper powder 13 a not adhering to 2 is shaken off and removed from the ceramic green sheet 11 to form a circuit pattern 14.

Then, as shown in FIG. 1D, in a fourth step, a copper powder 13 for forming a circuit pattern 14 of the ceramic green sheet 11 is fixed by a heat roller using a fixing roller 15a and a pressure roller 15b. To fix.

After the ceramic green sheet 11 obtained as described above is fired, and the resin component of the circuit forming pattern 12 is burned and scattered, the line width of the circuit pattern 14 is confirmed to be at least about 50 μm. Was.

FIG. 2 is a sectional view of an adhesive resin used in the circuit pattern forming method shown in FIG. The adhesive resin 16 is obtained by mixing a charge control agent 17 composed of an azo-based metal dye, an external additive 18 composed of silica, and a hot-melt resin 19 composed of polyester at a weight ratio of 1: 1: 98. 17 and an external additive 18 are uniformly dispersed in a hot-melt resin 19. In addition, the external additive 18 improves the fluidity of the adhesive resin,
It is included for adjusting the triboelectric charge amount.

FIG. 3 shows a configuration diagram of an electrophotographic apparatus for performing the first step of the circuit pattern forming method of FIG.
The electrophotographic apparatus 20 includes a photoconductor 21, a corona charger 22 for charging the surface of the photoconductor 21, and a laser beam 23 for forming a latent image pattern (not shown) on the surface of the photoconductor 21. The adhesive resin 16 on the latent image pattern of the photoconductor 21.
And a transfer unit 25 for transferring the adhesive resin 16 on the latent image pattern onto the ceramic green sheet 11 and fixing the adhesive resin 16 transferred onto the ceramic green sheet 11. And a flash lamp 26 for forming the circuit forming pattern 12 on the ceramic green sheet 11.

FIG. 4 shows an example of the electrophotographic apparatus shown in FIG.
FIG. 5 is a process chart in the case where the first step of the circuit pattern forming method is performed.

First, as shown in FIG. 4A, in the charging step, the surface of the photosensitive member 21 is negatively charged by the corona charger 22. Next, as shown in FIG. 4B, in the exposure step, the surface of the photoconductor 21 is irradiated with laser light 23,
Latent image pattern 27 from which electric charge has been erased on the surface of photoconductor 21
To form

Next, as shown in FIG. 4C, in the developing step, the negatively charged adhesive resin 16 is applied to the latent image pattern 27 on the surface of the photoreceptor 21 by electrostatic force and developed. Next, as shown in FIG.
The transfer unit 25 applies a positive charge having a polarity opposite to that of the adhesive resin 16 to the ceramic green sheet 11 from the rear surface of the ceramic green sheet 11, and applies the adhesive resin 16 developed on the latent image pattern 27 to the ceramic green sheet 11.
Transfer to the top.

Next, as shown in FIG. 4E, in the fixing step, the adhesive resin 16 transferred onto the ceramic green sheet 11 is fixed by irradiating a flash lamp 26 to form a circuit forming circuit on the ceramic green sheet 11. The pattern 12 is formed.

According to the above-described circuit pattern forming method, since the method includes the third step of removing unnecessary copper powder not adhering to the circuit forming pattern on the ceramic green sheet from the ceramic green sheet, it is unnecessary. All copper powder can be recovered. Therefore, since the copper powder does not adhere to unnecessary portions on the ceramic green sheet, it is possible to prevent problems such as short circuit when forming a circuit pattern.

Further, since the recovered copper powder can be reused, the production cost can be reduced.

Further, since the method includes a fourth step of fixing the copper powder for forming the circuit pattern on the ceramic green sheet by a heat roller using a fixing roller and a pressure roller, the surface of the circuit pattern is flattened. Accordingly, the degree of filling of the circuit pattern with the copper powder can be increased, and the sheet resistance of the circuit pattern can be reduced.

In the first step, a charge control agent is contained in the adhesive resin, and a circuit forming pattern is formed on the ceramic green sheet by electrophotography.
A highly accurate circuit forming pattern can be formed.
As a result, a highly accurate circuit pattern can be formed.

FIG. 5 is a sectional view showing one embodiment of the multilayer wiring board according to the present invention. The multilayer wiring board 30 includes first to third
Ceramic green sheets 311 to 313 are provided.
Then, the first and second ceramic green sheets 31
1, 312, the above-mentioned circuit pattern forming method (FIG. 1)
Thus, circuit patterns 321 and 322 are formed. Next, the first to third ceramic green sheets 311 to 311
13 are laminated, pressurized, integrally molded, and fired.

Note that the circuit patterns 321 and 322 on the first and second ceramic green sheets 311 and 312 are provided.
Are connected by a via hole 33, which is formed by an existing technology. For example, there is a method of press-fitting a conductor into each via hole using a conductor drawing apparatus. In this case, the circuit patterns 321, 322
After the formation of the via holes 33, the powder may damage the nozzles of the drawing machine if the via holes 33 are formed.
It is preferable to form the via hole 33 before forming the holes 21 and 322.

According to the above-described multilayer wiring board, a circuit pattern is formed on the ceramic green sheet by a circuit pattern forming step including a step of removing unnecessary copper powder present in areas other than the circuit forming pattern from the ceramic green sheet. After that, since the ceramic green sheets are laminated and formed by a normal manufacturing method, a short circuit of a circuit pattern constituting the multilayer wiring board after firing can be prevented. Therefore, it is possible to improve the function of the multilayer wiring board constituted by this circuit pattern.

In the circuit pattern forming methods of the first and second embodiments, the case where a circuit forming pattern is formed on a printing material by electrophotography has been described. However, an ink jet method or a thermal transfer method is used. The same effect can be obtained.

Also, the case where the substrate to be printed is a ceramic green sheet has been described, but the same effect can be obtained with a fired ceramic substrate such as an alumina substrate.

Further, the case where copper is used as the metal to be sprayed on the heated printing material has been described. The same effect can be obtained by using.

In place of the metal, a metal oxide such as copper oxide, barium oxide, titanium oxide and silica may be used. In this case, the metal oxide plays a role in strengthening the adhesion between the circuit pattern and the fired printing material when firing the printing material on which the circuit pattern is formed. Therefore, after the firing, the adhesive strength between the fired printed material and the circuit pattern is improved, so that the circuit pattern can be prevented from peeling off from the printed material.

Further, the case where the adhesive resin is composed of a heat-meltable resin has been described, but the same effect can be obtained with a pressure-deformable resin such as polyethylene or styrene / butadiene rubber. In this case, a pressure roller may be used in the transfer step or the fixing step.

[0035]

According to the circuit pattern forming method of the present invention, unnecessary metals or metal oxides that are not adhered to the circuit forming pattern formed on the substrate by the adhesive resin are removed from the substrate. Because it includes the third step,
All unnecessary metals or metal oxides can be recovered. Therefore, since metal or metal oxide does not adhere to unnecessary portions on the printing substrate, problems such as short circuits can be prevented when a circuit pattern is formed.

Further, since the recovered metal or metal oxide can be reused, the manufacturing cost can be reduced.

According to the circuit pattern forming method of the second aspect, since the method includes the fourth step of fixing the metal or metal oxide for forming the circuit pattern on the printing substrate by fixing with a heat roller, the surface of the circuit pattern is formed. And the degree of filling of the circuit pattern with the copper powder can be increased, and the sheet resistance of the circuit pattern can be reduced.

According to the circuit pattern forming method of the third aspect, in the first step, the charge control agent is contained in the adhesive resin, and the circuit forming pattern is formed on the substrate by electrophotography. Circuit forming patterns can be formed. As a result, a highly accurate circuit pattern can be formed on the printing substrate.

According to the multilayer wiring board of the fourth aspect, the circuit pattern forming step includes the step of removing unnecessary copper powder other than the circuit forming pattern from the ceramic green sheet. To form, then, by laminating those ceramic green sheets by a normal manufacturing method,
After firing, it is possible to prevent a short circuit of a circuit pattern constituting the multilayer wiring board. Therefore, it is possible to improve the function of the multilayer wiring board constituted by this circuit pattern.

[Brief description of the drawings]

FIG. 1 is a process chart of an embodiment of a circuit pattern forming method according to the present invention.

FIG. 2 is a sectional view of an adhesive resin used in the circuit pattern forming method of FIG.

3 is a configuration diagram of an electrophotographic apparatus used in the circuit pattern forming method of FIG.

FIG. 4 is a process chart of a first step of the circuit pattern forming method of FIG. 1; .

FIG. 5 is a sectional view of one embodiment of a multilayer wiring board according to the present invention.

[Explanation of symbols]

11, 311 to 313 Ceramic green sheet (substrate to be printed) 12 Circuit forming pattern 13 Copper powder (metal) 14, 321, 322 Circuit pattern 16 Adhesive resin 17 Charge control agent 30 Multilayer wiring board

Claims (4)

[Claims] 1. A circuit pattern forming method for forming a circuit pattern on a printing substrate, comprising: a first step of forming a circuit forming pattern on the printing substrate with an adhesive resin; A second step of spraying a metal or a metal oxide and adhering the metal or the metal oxide to the circuit forming pattern; A third step of removing unnecessary metal or metal oxide not adhering to the pattern from the printing substrate and forming the circuit pattern on the printing substrate;
And a step of forming a circuit pattern. 2. A circuit pattern forming method for forming a circuit pattern on a printing substrate, comprising: a first step of forming a circuit forming pattern on the printing substrate with an adhesive resin; A second step of spraying a metal or a metal oxide and adhering the metal or the metal oxide to the circuit forming pattern; A third step of removing unnecessary metal or metal oxide not adhering to the pattern from the printing substrate and forming the circuit pattern on the printing substrate;
And a fourth step of fixing the metal or the metal oxide that forms the circuit pattern on the printing medium by fixing with a heat roller. 3. The method according to claim 1, wherein in the first step, a charge control agent is contained in the adhesive resin, and the circuit forming pattern is formed on the printing material by electrophotography. Item 3. The method for forming a circuit pattern according to Item 2. 4. The method according to claim 1, wherein the substrate to be printed is a ceramic green sheet, and the ceramic green sheet on which the circuit pattern is formed is laminated and fired by the circuit pattern forming method according to claim 1. A multilayer wiring board characterized by being formed by: