JP2003198100A - Method for manufacturing board having electric circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a board having an electric circuit formed to allow a pattern width and a pattern interval to be increased in densities by forming the circuit by a method not needing a plating step. <P>SOLUTION: The method for manufacturing the board having an electric circuit comprises the steps of manufacturing a thin film 11 from a metal fine particle dispersion liquid on the board 5, and irradiating the film 22 with a laser beam to aggregate metal fine particles on a groove-like circuit pattern 13 to form a conductor. Thus, the film 11 laminated on the board 5 is directly irradiated with the beam to form a sufficient conductor. A later plating step is not required to simplify the steps, and further the pattern width and the pattern interval can be increased in densities in the electric circuit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a substrate on which an electric circuit is formed. More specifically, the present invention relates to a method of directly irradiating a metal fine particle dispersed film laminated on a substrate with laser light to form metal fine particles in a groove-shaped circuit pattern. Is a method of manufacturing a substrate in which an electric circuit is formed by aggregating a conductor to form a conductor.

[0002]

2. Description of the Related Art As a method of forming a circuit on a substrate by plating, a "photoimaging method" is known in which a photomask is applied to the substrate and exposed by an ultraviolet lamp.
This method is basically a method for manufacturing a printed wiring board using the "semi-additive method" or "subtractive method" that is performed on the current glass epoxy board. This is not preferable from the point of view of resource saving because there is a limitation in the above and plating of unnecessary portions is removed by etching.

As another method, the "full-additive method" has come to be used for the purpose of eliminating the etting removal of unnecessary portions. Further, there is a "direct exposure method" using laser light in order to further increase the pattern width and the pattern interval.

In addition to the "direct exposure method" using laser light, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-309267, oil such as grease is adhered to the resin surface and laser light is applied to the surface. There is a method of irradiating with and marking a character or the like, and a method of applying and fixing a resin containing an inorganic pigment as disclosed in JP-A-8-174263.

Recently, there is a "direct exposure method" in which a laser beam is directly irradiated for the purpose of further increasing the pattern width and the pattern interval.

[0006]

However, the above-mentioned "full additive method" is basically used for manufacturing a printed wiring board using the "semi-additive method" or "subtractive method" that is performed on the current glass epoxy substrate. Since this is a method, the pattern width and pattern interval are limited due to the use of an ultraviolet lamp, and plating of unnecessary portions is removed by etching, which is not preferable from the viewpoint of resource saving. The "Full Additive Method" developed for the purpose of eliminating it is because the catalyst remains in the circuit unnecessary part and it is exposed by an ultraviolet lamp.
There was a limit to the pattern width and pattern interval.

Further, the "direct exposure method" using a laser beam developed for the purpose of further increasing the pattern width and the pattern interval is a "subtractive method" using a laser for exposure, and the substrate is etched. After applying a catalyst, etc., electroless plating and copper plating were formed on the entire surface by electroplating, and after forming a plating resist film on this copper plating, the circuit pattern was imaged using laser light, and the image was obtained. Nickel, solder, gold or the like is electrolytically plated as an etching resist on the circuit portion. After removing the plating resist, copper etching was performed.
However, although it is an effective method for forming a complicated circuit pattern or fine pattern, it is not preferable in terms of resource saving because the plating of an unnecessary portion is removed by etching.

The present invention solves the above problems and manufactures an electric circuit formed by a method that does not require a plating step and can increase the pattern width and the pattern interval. The purpose is to provide a method.

[0009]

That is, the invention according to claim 1 of the present application is to produce a thin film from a fine metal particle dispersion on a substrate,
In a method for producing a substrate having an electric circuit, characterized in that a conductor is formed by aggregating metal fine particles in a groove-shaped circuit pattern by irradiating the thin film with laser light, and a metal having laser light laminated on the substrate. Directly irradiates the thin film obtained from the fine particle dispersion liquid to agglomerate the metal fine particles in the groove-shaped circuit pattern to form a sufficient conductor, and the subsequent plating step is unnecessary and the process is simplified. It is possible to obtain an electric circuit capable of achieving high density of the pattern width and the pattern interval.

The invention according to claim 2 of the present application is in the method for producing a substrate having an electric circuit in which the metal fine particle dispersion contains conductive powder, wherein the conductive powder is agglomerated by laser light irradiation. The gap is filled to improve conductivity.

The third aspect of the present invention is a method for producing a substrate having an electric circuit in which the metal fine particles are at least one selected from gold fine particles and silver fine particles.

The invention according to claim 4 of the present application is the method for producing a substrate on which an electric circuit is formed, wherein the amount of the metal fine particles added is 25% by weight or more based on the total weight of the solid content of the metal fine particle dispersion, and the laser is used. In the step of irradiating light, the light energy of the laser light can be fully utilized, and a fine and clear pattern circuit can be formed.

The invention according to claim 5 of the present application is the method for producing a substrate having an electric circuit in which the amount of the conductive powder added is 0 to 50% by weight or more based on the total weight of the solid content of the fine metal particle dispersion. The conductive powder is filled in the gaps between the metal fine particles aggregated by the irradiation of the laser beam to enhance the electrical conductivity.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. A metal fine particle dispersed film is previously formed on the surface of the substrate. The metal fine particle dispersant that forms the metal fine particle dispersion film contains at least three kinds of a metal fine particle dispersion liquid in which metal fine particles are independently dispersed in a solvent or a protective polymer, a polymer matrix, and a solvent. The laser light energy absorbed by the metal fine particle dispersion film is released as heat by irradiating the laser light having the wavelength corresponding to the metal fine particle dispersion thin film showing the absorption spectrum of
This heat sublimates or melts the polymer matrix,
A conductor is formed on the plastic substrate because the metal fine particles aggregate.

The addition amount of the metal fine particles in the metal fine particle dispersion is the total weight of the solid content of the metal fine particle dispersion (metal fine particles,
25% by weight or more, preferably 50 to 95% by weight, based on the conductive powder, polymer, etc., and if less than 25% by weight, the light energy of the laser beam is sufficiently utilized in the step of irradiating the laser beam. However, it becomes difficult to form a fine and clear pattern circuit.

The fine metal particle dispersion used here is a dispersion of fine metal particles having a particle size of 0.001 to 3 μm independently in a solvent. For example, the gas disclosed in JP-A-3-34211. It is manufactured by a method called the medium evaporation method. This is obtained by introducing a helium-inert gas into the chamber to evaporate the metal, cooling by condensation with an inert gas, and condensing.In this case, α-terpineol is generated at the stage where the particles immediately after generation are in an isolated state. , And the vapor of a solvent such as toluene is introduced to coat the surface of the particles. Further, as other production methods, generally well-known reduction method, atomization method and the like are known.

The other metal fine particles are obtained by heating and melting a polymer or oligomer having at least one kind of functional group selected from a cyano group, an amino group and a thiol group at the terminal or side chain of the molecule, and then melting it. A metal such as gold, platinum, palladium, rhodium, or silver is evaporated to be trapped in a melt of the protective polymer, and then dispersed in the molten protective polymer. Then, the polymer composite in which metal fine particles are dispersed in this polymer can be used by dissolving it in a solvent such as α-terpineol, methanol, ethanol, water, carbitol, and metacresol.

Specifically, the above protective polymer has a cyano group (-CN) or an amino group (-N) at the terminal or side chain of the molecule.
H ₂ ), and at least one functional group selected from thiol groups (—SH), the skeleton of which is polyethylene oxide, polyethylene glycol, polyvinyl alcohol, nylon 11, nylon 6, nylon 6, nylon 6,
6, nylon 6,10, polyethylene terephthalate,
It is made of polystyrene and has a melting point or softening point of 4
It is 0 to 100 ° C. The average molecular weight of the oligomer is not particularly limited, but is about 500 to 6000. The above-mentioned functional group is particularly likely to form a covalent bond or a coordinate bond with a metal atom on the surface of the fine particles, suppresses grain growth, and enhances dispersibility of the fine particles.

In addition, as disclosed in, for example, Japanese Patent Publication No. 6-99585, copper is formed on the surface of a polymer layer such as nylon 11 which is thermodynamically nonequilibrium by being rapidly solidified after melting. After vapor deposition of these alloys containing gold, silver, lead, and platinum, or copper, the polymer layer is relaxed to equilibrium, thereby atomizing the metal and dispersing it in the protective polymer. Can be obtained. Then, a polymer composite in which fine particles are dispersed in this polymer is dissolved in a solvent such as α-terpineol, methanol, ethanol, carbitol, and metacresol for use.

The metal fine particle dispersion is dispersed in a polymer matrix to obtain a metal fine particle dispersant. In the present invention, ethyl cellulose, ethyl hydroxyethyl cellulose or the like is used as the polymer matrix.

The solvent may be any solvent which can dissolve the above-mentioned polymer matrix, and examples thereof include toluene, xylene, terpineol and cyclohexane.

The metal fine particle dispersant may contain a conductive powder. This conductive powder is filled in the gaps of the metal fine particles agglomerated by the irradiation of laser light to enhance the electrical conductivity, and specifically, tin oxide-doped indium oxide powder (ITO powder), antimony-doped tin oxide powder (ATO powder). ). Tin oxide, zinc oxide, cadmium oxide,
Alternatively, a conductive oxide such as titanium oxide coated with these is preferable, and one in which the oxide serves as an insulator is not preferable.

The particle size of this conductive powder is usually from 0.05 to
It is 10 μm, and if it exceeds 10 μm, it cannot be filled in the gaps of the metal fine particles in which the conductive powder is aggregated, and the electrical conductivity is deteriorated. Further, the amount of the conductive powder added is 0 to 50% by weight based on the total weight of the solid content of the metal fine particle dispersion, and if it exceeds 50% by weight, the amount of the metal fine particles is small and the electrical conductivity is poor. come.

The thickness of the thin film in which the fine metal particles are dispersed is
0.5 to 30 μm is preferable, and 15 to 2 is more preferable.
It is about 0 μm. The thickness of the thin film can be easily adjusted by appropriately adjusting the amounts of polymer and solvent used. If the film thickness is less than 0.5 μm, sufficient absorbance of the thin film cannot be obtained, and the laser beam irradiation energy required for groove pattern processing becomes large, which is not preferable.

When the dispersion state of the metal fine particles in the polymer is poor, it becomes difficult to obtain a unique absorption spectrum based on the interaction between the metal fine particles and the polymer, and the obtained thin film has a broad absorption spectrum. Indicates. This leads to a reduction in the sensitivity of the thin film to laser light. In this case, too, it is necessary to irradiate the laser beam excessively, and therefore it is necessary to uniformly disperse the metal fine particles in the polymer.

The light absorption characteristics of the thin film obtained differ depending on the type of the metal fine particles used.
In the vicinity of nm, silver fine particles give a thin film having an absorption maximum near 430 nm.

The metal fine particles may be coated on the substrate in the state of being dispersed in the organic solvent as the metal fine particle dispersant, in addition to the metal fine particle dispersed film dispersed in the polymer as described above. At this time, due to the effect of the surfactant added to the commercially available metal fine particle dispersant, the metal fine particles do not aggregate on the substrate, and a thin film having a color unique to the metal fine particle dispersion film similar to the above metal fine particle dispersion film. Are formed on the substrate.

As the substrate, methacrylic resin such as methylmethacrylate (PMMA) resin, polycarbonate (PC) resin, polyethylene (PE) resin, polypropylene (PP) resin, polystyrene (PS) resin, polyethylene terephthalate (PET), etc. Examples include various general-purpose plastics such as polyester resin, epoxy resin, phenol resin, polyvinyl chloride (PVC) resin, and glass. Each may remain colorless or may contain various colorants.

A plastic substrate having a gold fine particle dispersed thin film (hereinafter referred to as thin film 11) formed on its surface is irradiated with laser light by the laser light irradiation system shown in FIG. 1 to perform pattern processing. The laser light source 1 is not particularly limited as long as it is within the absorption wavelength range of the thin film 11, but if the sensitivity of the thin film 11 to the laser light is taken into consideration, a wavelength in the vicinity of the maximum absorption wavelength of the thin film 11 is obtained. Those having are preferred. A small output of about a dozen milliwatts is sufficient, and for example, 430 nm, 488n
A laser that oscillates light in the visible region of m, 532 nm, 633 nm, or the like is preferably used. The laser light intensity on the processed surface is preferably 2 mW or more. The laser light intensity is adjusted by the amount of absorption of the thin film 11, and if the laser intensity is too high, the unevenness of the substrate becomes large, which hinders the electrical conductivity. Considering the gist of the present invention in which pattern processing is performed with a weak laser beam, 30 mW or less is preferable.

The laser light is guided through the mirror 2 and the polarization beam splitter 3 onto the XYZ stage 4 on which the thin film 11 is placed. The thin film surface on the substrate 5 placed on the XYZ stage 4 which can be moved in three dimensions by driving a motor can be observed by the TV monitor 8 through the objective lens 6 and the CCD camera 7 directly above. Laser light is introduced into the thin film 11 with its intensity adjusted using the transmission filter 9. The laser light is narrowed down to about 1 to 20 μm on the thin film 11 by the objective lens 6. While observing the surface of the thin film 11 on the TV monitor 8, move the XYZ stage 4 to X.
It drives according to a desired pattern in the Y direction.

When the substrate 5 is taken out, as shown in FIG. 2, a groove-shaped circuit pattern 13 is formed at the portion irradiated with the laser beam. Then, the thin film 11 is formed, and an organic substance such as a polymer matrix is sublimated or melted, and at the same time, the circuit pattern 13 is a conductor in which metal fine particles are aggregated.

[0032]

EXAMPLES The method for manufacturing a substrate having an electric circuit according to the present invention will be described in more detail below with reference to examples.

Examples 1 to 4 and Comparative Examples 1 to 2 As shown in the formulation of Table 1, 5% by weight of ethyl cellulose and 95% by weight of p-xylene as a solvent were added to a container to give 1
After stirring for a while to dissolve, terpineol-dispersed gold particles (“Perfect Gold” Au 19.9 manufactured by vacuum metallurgy) were added.
(% By weight) and a predetermined amount of conductive powder are added and stirred for 30 minutes or more to prepare a gold fine particle dispersion liquid, which is dropped on a predetermined substrate and spin-coated (rotation speed: 2,000 rpm, time: 15 seconds). ), Create a thin film with a thickness of about 4 μm, and
It was dried for 0 minutes to obtain a gold fine particle dispersed film.

[0034]

[Table 1]

A green laser beam (wavelength: 532 nm, output: 25 mW) focused by an objective lens (NA: 0.25) while scanning the stage on the gold fine particle dispersion film.
Was used to form a circuit pattern having a predetermined width. The laser light intensity on the processed surface was 25 mW.

Then, both ends of the portion irradiated with laser light were coated with dotite, and the resistance was measured using a tester. The results are shown in Table 3.

Example 5, Comparative Example 3 As shown in the formulation of Table 2, 1% by adding 5% by weight of ethyl cellulose and 95% by weight of p-xylene as a solvent to a container.
After stirring and dissolving for a time, a predetermined amount of toluene-dispersed gold fine particles (vacuum metallurgy "Perfect Gold" Au 20% by weight) and a predetermined amount of toluene-dispersed ITO (tin-doped indium oxide) fine particles (Au 20% by weight) were added to give 30 Stirring for more than a minute to prepare a gold fine particle dispersion liquid, which is dropped onto a PMMA substrate and spin-coated (rotation speed: 1,000 rpm,
After forming a thin film having a thickness of about 12 μm for 20 seconds, it was dried at room temperature for 10 minutes to obtain a gold fine particle dispersed film.

[0038]

[Table 2]

A circuit pattern having a predetermined width was formed on the gold fine particle dispersion film by the same method as in Example 1. Then, the both ends of the portion irradiated with the laser beam were coated with dotite, and the resistance was measured using a tester. The results are shown in Table 3.

[0040]

[Table 3]

As a result, in Examples 1 to 4, a circuit having electrical conductivity was formed regardless of the type of the substrate, and in a circuit having a large amount of fine gold particles and a large film thickness, the resistance value was small and the electrical conductivity was small. You can see that is getting better. On the other hand, Comparative Example 1
It can be seen that Nos. 2 to 2 are circuits having no electrical conductivity because titanium oxide and copper powder having a particle size of 10 μm are used as the conductive powder.

In Example 5, it can be seen that when ITO fine particles are used as the conductive powder, a circuit having good electric conductivity is formed. Since Comparative Example 3 does not contain fine gold particles, it can be seen that the circuit has no electrical conductivity.

[0043]

As described above, in each claim of the present application, a thin film is prepared from a metal fine particle dispersion liquid on a substrate, and the metal fine particle dispersion film is irradiated with a laser beam to form a metal in a groove-shaped circuit pattern. In a method of manufacturing a substrate having an electric circuit in which fine particles are aggregated to form a conductor, a thin film obtained from a metal fine particle dispersion liquid laminated on a substrate is directly irradiated with laser light to form a groove-shaped circuit pattern. Can be aggregated to form a sufficient conductor, and the subsequent plating step is not required, and the process can be simplified, and an electric circuit capable of densifying the pattern width and pattern interval can be obtained. effective.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an apparatus for microfabrication of a substrate.

FIG. 2 is a perspective view of a substrate showing a circuit pattern formed after laser light irradiation.

[Explanation of symbols]

5 substrates 11 thin film 13 circuit patterns

Claims (5)

[Claims] 1. An electric circuit comprising: forming a thin film on a substrate from a metal fine particle dispersion liquid; and irradiating the thin film with laser light to agglomerate the metal fine particles into a groove-shaped circuit pattern to form a conductor. Of manufacturing a substrate having a. 2. The method for manufacturing a substrate having an electric circuit according to claim 1, wherein the fine metal particle dispersion contains a conductive powder. 3. The method for producing a substrate having an electric circuit according to claim 1, wherein the fine metal particles are at least one selected from fine gold particles and fine silver particles. 4. The method for producing a substrate having an electric circuit according to claim 1, wherein the addition amount of the metal fine particles is 25% by weight or more based on the total weight of the solid content of the metal fine particle dispersion liquid. 5. The method for producing a substrate having an electric circuit according to claim 1, wherein the conductive powder is added in an amount of 0 to 50% by weight or more based on the total weight of the solid content of the fine metal particle dispersion.