JP4983811B2 - Conductive circuit forming method and conductive circuit device - Google Patents

Description

  The present invention relates to a conductive circuit forming method and a conductive circuit device, and in particular, a conductive circuit forming method and a conductive method for forming a fine conductive thin film pattern on a substrate using ink containing fine particles of a conductive substance. The present invention relates to a circuit device.

  Generally, in printed wiring boards and wiring of semiconductor devices, semiconductor elements and various electronic components are mounted at high density. In order to perform such high-density mounting, fine wiring made of a conductive layer such as copper on the surface of a resin substrate or a material having an electrical insulation property such as a passivation film formed in a semiconductor manufacturing apparatus. A means for forming a pattern is used.

  As means for forming a copper wiring pattern on the surface of the resin substrate or the like, conventionally, two main methods by photolithography using an etching-resistant resin called a resist are known.

One method is a method called a subtractive method. Specifically, a copper foil previously provided on the entire surface of the resin substrate is immersed in a copper-soluble solution and etched to remove unnecessary copper foil portions and leave only a desired wiring pattern portion. Is the method.
In order to perform such position selective etching, it is necessary to cover the surface of the copper foil desired to be a wiring pattern with a resist before etching by the following method. First, a photosensitive resist is applied to the copper foil surface. Next, if a light image corresponding to a desired wiring pattern is exposed and developed, a resist film having a desired pattern can be obtained. Thereafter, the copper foil portion not covered with the resist is removed by etching, and a desired copper wiring pattern can be obtained by removing the resist by a predetermined method corresponding to the resist (see, for example, Patent Document 1). ).

Another method is called an additive method. Specifically, a wiring pattern is formed on a desired portion on a resin substrate or the like by an electroless plating method.
In this method, first, a nucleus serving as a catalyst for depositing copper is attached to the entire surface of the resin substrate when performing electroless copper plating performed in a later step. Next, a photosensitive plating resist film is provided on the entire surface of the resin substrate. Next, the surface of the resin substrate is coated with a plating resist having a desired wiring pattern by exposing and developing a light image corresponding to the desired wiring pattern on the surface. Subsequently, the resin substrate is immersed in an electroless copper plating solution, and copper is deposited on a portion not covered with the resist. Thereafter, the resin plating resist is peeled off, and a desired copper wiring pattern is formed on the surface of a resin substrate or the like (see, for example, Patent Document 2).

  The two methods are conventionally widely used as means for obtaining a printed wiring board, and the same method is used even when a metal other than copper or a conductive material is used.

  On the other hand, in contrast to the above-described photolithography method using a resist, a conductive wiring pattern forming method that does not use a resist and photolithography is also known.

The first is a metal wiring formation method using an electrochemical method. In this method, a thin film of a soluble copper precursor compound to be a metal foil is provided on a substrate, and copper is deposited by irradiating ultraviolet rays onto this specific part.
Specifically, a metal thin film such as copper of about 20 nm is deposited on a dielectric or glass substrate in advance on the entire surface of the substrate, and then immersed in an electrolytic solution containing copper sulfate, sulfuric acid, and glycol. A method of irradiating an Ar ⁺ ion laser in order to form a wiring pattern only on an irradiated portion while being dissolved as a metal precursor compound is known (for example, see Non-Patent Document 1). This method utilizes the fact that an electromotive force is generated in the portion irradiated with the laser beam, and an electrochemical reaction occurs to reach copper deposition.

The second is a metal wiring forming method using a laser beam regardless of the electrochemical method. In this method, wiring is formed by irradiating a metal thin film locally with a laser beam such as a wiring pattern shape.
Specifically, a metal colloid having the outer skin as a protective colloid is deposited on the substrate in a thin film shape as a precursor, and then the surface is irradiated with space-selective light to decompose or destroy the outer metal. A method of forming a thin film and then removing the metal colloid in the non-exposed area is shown. The space-selective light irradiation refers to local light irradiation for forming a wiring pattern based on a light image or repairing a broken wiring portion (see, for example, Patent Document 3).
In the formation of a wiring pattern by a light image, printing is performed by an ink jet method using ink in which fine particles of a conductive material are dispersed in a solvent, and light energy is drawn while drawing a desired pattern using a laser beam. There is also known a method of removing unnecessary portions after sintering (see, for example, Patent Document 4).

  The third is a metal wiring formation method using a thermosetting resin without using an electrochemical method or a laser beam. In this method, a wiring pattern is printed using a metal paste in which metal fine particles and a thermosetting resin are mixed, and the wiring is formed by heat curing (see, for example, Patent Document 5).

  The fourth is a metal wiring forming method using a method in which the entire substrate is heated and sintered without using a thermosetting resin. Specifically, there is a method in which fine particle ink containing conductive metal fine particles is locally and selectively deposited in a thin film shape on a substrate, and then the whole is heated and sintered (see, for example, Patent Document 6).

Japanese Patent Laid-Open No. 11-224978 JP 2005-174828 A JP 2001-23929 A US Pat. No. 5,132,248 JP 2002-324966 A JP 2007-220463 A

L. Mini, Applied Physics Letters, vol. 64 p. 3404-3406, 1994

  However, in the subtractive method in which the metal foil provided in advance on the entire surface of the substrate is removed by etching while leaving a desired portion, there is a possibility that an etching solution may enter when the wiring pattern is miniaturized. Therefore, precise dimensional accuracy cannot be obtained, and there is a risk of causing problems related to reliability such as disconnection.

  In addition, in the additive method in which a wiring pattern is formed on a desired portion on a resin substrate or the like by an electroless plating method, in order to obtain the desired wiring pattern, steps of resist coating, exposure with a precision optical system, and peeling are essential. Therefore, there is a limit in improving the productivity of printed wiring boards.

  On the other hand, the method using the electrochemical method has an advantage that it is difficult to deposit anything other than copper on the substrate surface due to the electrochemical action. In addition, by changing the sweep speed of the laser beam, the film thickness of the deposited copper can be varied within a certain range, but the reaction speed is slow, so that the film can be deposited to a sufficient film thickness. Need to draw over time. Therefore, there is a possibility that throughput decreases and cost increases. In addition, there is a process limitation that a metal precursor compound thin film must be provided on the entire surface of the substrate in advance. Further, the deposited copper is not uniform, and there is a possibility that the copper particles having a particle size of 0.1 to 0.3 μm may be in an uneven structure in which the copper particles are randomly bonded to each other.

  Furthermore, in the method of locally irradiating a metal thin film with a laser beam, such as a wiring pattern shape, it is possible to form a very fine line similar to photolithography by drawing a wiring pattern with a laser beam, and only to the necessary part by the inkjet method. Although the use of expensive ink can be avoided by applying ink, the metal thin film raw material of the non-exposed part is post-exposure, although it has a feature that the degree of freedom in the type of solvent is higher than the electrochemical method described above. Must be removed. For this reason, the utilization efficiency of the metal thin film raw material is deteriorated, resulting in an increase in cost and an increase in waste liquid treatment cost.

  Furthermore, in the method using the thermosetting resin, the resin remains in the wiring pattern because a method of hardening with the cured resin is used. Although this method can produce a conductive circuit pattern that is not fine but inexpensive for applications that may have a relatively high electrical resistance, the residual resin may deteriorate the conductivity. In addition, in a metal that is easily covered with an insulating oxide film such as copper, there is a risk that the conductivity is significantly lowered.

  Furthermore, in the method of heating and sintering the entire substrate, a cured resin is not used, so that a highly conductive electrical wiring can be formed. However, since the entire substrate is heated, there is a possibility that a substrate made of a resin having poor heat resistance cannot be used. .

  An object of the present invention is to provide a conductive circuit forming method and a conductive circuit device that realize sufficient conductivity, simple processes, sufficient circuit formation speed, and cost reduction.

A first aspect of the present invention is a method of forming a conductive circuit by cooling a substrate to room temperature or lower, printing a wiring pattern, and irradiating the wiring pattern with light, and printing the wiring pattern. Uses a conductive material containing fine particles having an average particle diameter of 20 nm or less, and the irradiation optical system for irradiating the wiring pattern with light has a light generation optical system for generating light, and the light irradiation pattern has a belt shape. A shaping optical system for shaping so that the irradiation pattern of the light irradiated by the irradiation optical system is moved relative to the substrate so that the wiring pattern passes the light. The light is irradiated over the entire width of the wiring pattern printed on the substrate.
According to a second aspect of the present invention, in the method for forming a conductive circuit by printing a wiring pattern on a substrate and irradiating the wiring pattern with light, the wiring pattern is printed with an average particle diameter of 20 nm or less. A light generating optical system that generates light, and shaping optics that shapes the light irradiation pattern into a band shape A roll cooled to room temperature or lower is brought into contact with the substrate, and the irradiation pattern of the light irradiated by the irradiation optical system is set so that the wiring pattern passes through the light with respect to the substrate. The light is irradiated over the entire width of the wiring pattern printed on the substrate by being relatively moved.

According to a third aspect of the present invention, in the invention according to the first or second aspect, the light is visible light.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the shaping optical system shapes the light applied to the substrate so as to have a uniform intensity distribution. To do.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the fine particles are a metal containing any one of gold, silver, and copper.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the fine particles include an oxide of a metal containing any one of gold, silver, and copper. .

According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the substrate is any one of a polyimide substrate, a polyethylene terephthalate substrate, a polyethylene naphthalate substrate, and a liquid crystal polymer substrate. It is characterized by.

According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the light source of the light generation optical system includes a laser oscillator.

According to a ninth aspect of the present invention, in the invention described in the eighth aspect, a solid state laser is used as the laser oscillator.

According to a tenth aspect of the present invention, in the invention described in the ninth aspect, a nitride semiconductor laser diode or a YAG laser is used as the solid-state laser.

An eleventh aspect of the present invention is the invention according to any one of the first to tenth aspects, wherein the irradiation optical system includes a cylindrical lens, an Fθ lens, or both. To do.

A twelfth aspect of the present invention is the invention according to any one of the first to eleventh aspects, wherein the irradiation optical system is a combination of any one of a slit, a lens, a mirror, a shutter, an optical filter, and an optical fiber. Or an optical system composed of all combinations.

According to a thirteenth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the light source of the light generation optical system is a light emitting diode, a halogen lamp, an arc lamp, a flash lamp, a mercury lamp, It is one of incandescent bulbs.

According to a fourteenth aspect of the present invention, in the invention according to any one of the first to thirteenth aspects, the irradiation optical system includes an optical system that blocks light having a wavelength of 300 nm or less and a wavelength of 700 nm or more. It is characterized by that.

A fifteenth aspect of the invention is a conductive circuit device having a conductive circuit created by using the conductive circuit forming method according to any one of the first to fourteenth aspects.

  According to the present invention, sufficient conductivity, a simple process, a sufficient circuit formation speed, and cost reduction can be realized.

It is explanatory drawing of the conductive circuit formation method in one Embodiment of this invention. It is explanatory drawing of the conductive circuit formation method in other embodiment of this invention. It is the figure which showed the relationship between the average particle diameter in one Example and comparative example of this invention, electrical conductivity, and adhesiveness. It is the figure which showed the relationship between the kind of metal in another Example of this invention, electrical conductivity, and adhesiveness. It is the figure which showed the relationship between the kind of board | substrate in another Example of this invention, electrical conductivity, and adhesiveness. It is the figure which showed the relationship between the kind of light source and wavelength in another Example of this invention, electrical conductivity, and adhesiveness.

The inventors have studied various methods for forming a conductive circuit capable of realizing sufficient conductivity, simple process, cost reduction, and sufficient circuit formation speed.
The inventors first focused on a method of forming a conductive thin film by irradiating light.
However, as described above, the light irradiation method using the metal precipitation phenomenon caused by the electrochemical reaction of the precursor substance may cause various problems.
Therefore, the inventors use a dispersion liquid in which nanometer-sized conductive material fine particles are dispersed in a solvent (hereinafter also referred to as fine particle ink), heat the fine particles by light absorption, and sinter the fine particles. We focused on the effectiveness of the method.
In particular, when the fine particles are made of a conductive material having a diameter of about 20 nm or less, the melting point is remarkably lowered.
Furthermore, when the fine particles have a size of about 20 nm or less in diameter, due to the quantum size effect, specific light absorption by the surface plasmon of the metal occurs from the blue to the ultraviolet region, and together with this, a wide wavelength range from the visible region to the ultraviolet region. Focusing on the feature that light can be efficiently heated by light because of light absorption.

  However, the conventional method using laser light irradiation has an advantage that a desired wiring pattern can be obtained without using a resist. However, since fine wiring lines are sequentially drawn by laser scanning, a long drawing time is required. For this reason, there is a difficulty in throughput simply by using the conventional method of laser light irradiation.

Therefore, the inventors formed a desired wiring pattern on a substrate using a printing method that is easy to mass-produce and has a high throughput, and then collectively irradiated with light having an irradiation pattern spread in a strip shape. As a result, it was found that a desired conductive circuit wiring pattern can be efficiently sintered and formed.
Based on this knowledge, the form for implementing this invention is demonstrated, using drawing.

FIG. 1 shows a schematic configuration of an apparatus using the conductive circuit forming method according to the present embodiment.
As shown in FIG. 1, the apparatus using the conductive circuit forming method according to the present embodiment includes rolls 1 and 4 used for winding the substrate 14 on which the conductive circuit is formed, and the substrate 14. The printer 2 is used for printing a wiring pattern of a desired conductive circuit, and an irradiation optical system is used for irradiating the printed line pattern with light 10.

First, the substrate 14 is, for example, a base having a long shape, and a TAB (Tape Automated Bonding) tape or COF (Chip on Film) in which a wiring pattern of a desired conductive circuit is formed on the substrate 14. Used in the manufacture of
When manufacturing a TAB tape or a COF tape having a wiring pattern formed on a long substrate 14 in this way, it is manufactured using a roll-to-roll method. That is, as shown in FIG. 1, the long substrate 14 is conveyed in the direction of the arrow by rotating the delivery side roll 1 and the take-up side roll 4 in the direction of the arrow.

  As the substrate 14, for example, a resin substrate can be used in addition to a glass substrate and a ceramic substrate. In particular, in the resin substrate, Teflon (registered trademark) resin, liquid crystal polymer resin, epoxy resin, ketone resin, polyimide resin, modified polyimide resin, polyethylene resin, phenol resin, fluororesin, bismaleide triazine resin, polyester resin, polybutadiene A wide variety of resin substrates and resin films such as polysulfone, polyethersulfone, polyetherimide, and polyetheretherketone can be used.

  Next, the wiring pattern of a desired conductive circuit is printed on the substrate 14 by passing the substrate 14 through the printing machine 2. A conventional printing machine may be used as the printing machine 2, and examples thereof include a flexographic printing machine that is easy to mass-produce and has a high throughput.

For the printing of the wiring pattern by the printer 2, fine particle ink made of a conductive material is used.
Examples of the conductive material 2 include various metals, metal compounds, and oxides thereof. Examples of the metal include gold, silver, copper, platinum, aluminum, nickel, tin, titanium, manganese, indium, gallium, zinc, magnesium, tantalum, chromium, molybdenum, and tungsten. Further, alloys of these metals and intermetallic compounds may be used, and oxides, nitrides and carbides of these metals and alloys may be used. Other promising metals include ruthenium, rhodium, palladium, osmium, and iridium, which are called platinum groups, although it is difficult to obtain nanoparticles.
For the fine particle ink made of the conductive material, a conductive material containing fine particles having an average particle size of 20 nm or less is used. As described above, when a conductive material containing fine particles having an average particle diameter of about 20 nm or less is used, the melting point is remarkably lowered, and efficient heating with light becomes possible.
The average particle diameter is an average diameter obtained from the particle size distribution measured with a transmission electron microscope, and the average diameter is an integrated value of 50% obtained by integrating the particle size distribution from the small particle diameter side. It is the grain size of.
The fine particle ink is preferably in the form of a paste or liquid and is suitable for application, and the viscosity is preferably adjusted by adjusting the amount of solvent as necessary. In order to improve the dispersibility and coating uniformity of the metal fine particles in the solvent, the metal fine particles may be provided with an appropriate organic condensation prevention layer such as a surfactant.

  Next, the wiring 10 printed on the substrate 14 is irradiated with light 10 using an irradiation optical system. By this light irradiation, a wiring pattern made of a conductive material is sintered on the substrate 14 to produce a TAB tape and a COF tape. As a result, a conductive circuit device is produced from these tapes.

  The irradiation optical system includes a light generation optical system that generates the light 10 and a shaping optical system that shapes the irradiation pattern of the light 10 into a band shape.

In the light generation optical system, light 10 is generated by a light source 9. The light 10 is preferably visible light. The light source 9 may be any light source that generates visible light 10, but is preferably a laser oscillator. This is because the light source which is a laser oscillator is easy to handle in the design of the optical system. In addition, since collimation is easy because it emits a beam with high parallelism, it has the advantage of simplifying the optical system such as mirrors and lenses, and there is no need for a cut filter for monochromation, enabling effective light output. This is because it can be used.
Examples of the laser oscillator include gas lasers such as Ar lasers and Ho—Cd lasers, semiconductor lasers such as gallium nitride laser diodes, and solid-state lasers such as YAG and YV04. This is because the laser is relatively inexpensive and easy to use.

  Next, in the shaping optical system, the irradiation pattern of the visible light 10 (hereinafter also referred to as laser 10) generated by the light generation optical system is shaped so as to be a band shape. The irradiation pattern of the laser 10 is preferably shaped so as to have a uniform intensity distribution in addition to a strip shape.

In order to shape the irradiation pattern of the laser 10, the laser 10 is reflected by the plane mirror 8, and the reflected laser 10 passes through either the cylindrical lens 7, the Fθ lens 6, or both. It is preferable to do. This is because the irradiation pattern of the laser 10 is spread as uniformly as possible while suppressing the intensity distribution of the laser 10.
Examples of the cylindrical lens 7 include a plano-concave lens. Further, if necessary, a plano-convex lens can be combined so as to be orthogonal thereto, and the focus of the laser 10 can be adjusted, and at the same time, the effective light intensity can be changed.
Further, by inserting the Fθ lens 6 into the optical system, it is possible to prevent the laser intensity from being lowered at both ends in the film width direction due to the widening of the laser irradiation unit 5.

Then, as shown in FIG. 1, the shaping optical system shapes the irradiation pattern of the laser 10 into a band shape so as to obtain a uniform intensity distribution, and moves the laser irradiation unit 5 relative to the substrate 14. .
For example, as shown in FIG. 1, by transporting the substrate 14 with the rolls 1 and 4 with respect to the laser 10 having a strip-shaped irradiation pattern in which the irradiation position of the laser irradiation unit 5 is fixed, at least the wiring pattern portion The substrate 14 is passed through the laser 10 at a right angle so as to include the full width. Preferably, the substrate 14 is passed through the laser 10 so that the full width of the substrate 14 is included.
Conversely, the belt-like laser 10 may be moved relative to the fixed substrate 14 in order to sinter the entire width of the wiring pattern made of a conductive material printed on the substrate 14. In this case, the irradiation optical system itself or a part thereof may be moved, or the laser irradiation unit 5 irradiated to the substrate 14 by changing the inclination of the plane mirror 8, the cylindrical lens 7, the Fθ lens 6 and the like. May be moved.

  If the entire width of the substrate 14 passes through the laser irradiation unit 5, the laser irradiation unit 5 may be inclined instead of being orthogonal to the conveyance direction of the substrate 14. Further, the width of the laser 10 having a strip-shaped irradiation pattern irradiated on the substrate 14 is not limited to being thin like a line, but if an appropriate surface intensity can be obtained upon light irradiation, the laser 10 can be obtained. It is also possible to expand the width of the irradiation pattern to form a wide band. Further, the belt-shaped irradiation pattern of the laser 10 may be curved to such an extent that unevenness in light irradiation onto the substrate 14 does not occur.

  In other words, in the present embodiment, the laser 10 having the irradiation pattern of the belt-like and uniform intensity distribution is simultaneously and collectively irradiated so that the entire width of the wiring pattern portion is included in the laser irradiation unit 5. As a result, in the present embodiment, the wiring pattern is simultaneously and collectively sintered in the laser irradiation unit 5 in the wiring pattern on the substrate 14.

As described above, by simultaneously and collectively sintering the wiring pattern using the laser 10 having the irradiation pattern having a strip shape and a uniform intensity distribution, the following advantages are obtained.
That is, if the irradiation pattern of the laser 10 is spread in a band shape, the entire surface of the substrate 14 can be sintered only by passing the substrate 14 printed with the wiring pattern through the laser irradiation unit 5.
In addition, the wiring can be formed without damaging the substrate 14 while having the advantage that the entire surface of the substrate 14 can be sintered. Specifically, the temperature of the fine particles is rapidly increased by light absorption when irradiated with light, and is considered to be fused and fused with adjacent particles. Furthermore, it is considered that adhesion is also caused at the interface with the substrate 14 by physical and chemical effects. At this time, since the temperature rise of the fine particles is extremely high, the temperature rise around the fine particles due to heat conduction is slight, even if the substrate 14 is formed of a resin film having relatively no heat resistance, Wiring can be formed without melting the entire resin film.
Furthermore, as shown in FIG. 1, in this embodiment, since the wiring pattern can be printed and sintered by light irradiation while moving the long substrate 14 uniformly and continuously, it is excellent in mass productivity.
As a result, since the wiring can be sintered only by passing through the substrate 14, a sufficient circuit formation speed can be realized without requiring a long drawing time as in the prior art.

  As shown in FIG. 2 in which a modification of the present embodiment is described, any of the slit 12, the optical filter 13, the lens 11, the mirror, the shutter, and the optical fiber (not shown) is used in the irradiation optical system. It is preferable that the optical system which consists of these combinations or all the combinations is included. This is because it is easy to control the laser intensity, wavelength, shape, etc., suppresses the influence of noise due to ambient light, etc., and increases the degree of freedom in the installation position of the device, enabling a more compact arrangement.

So far, the case where the light source 9 of the light generation optical system is a laser has been described. However, the light source 9 may be any of a light emitting diode, a halogen lamp, an arc lamp, a flash lamp, a mercury lamp, and an incandescent bulb. Good. When a light-emitting diode with a high output is used as the light source 9, since it is a monochromatic light source, a filter is unnecessary and it is relatively easy to use. In addition, when these light sources are used, there are advantages that various wavelengths can be selected, that the light source device is not monochromatic light, and that the light source device is relatively inexpensive.
In addition, the light source 9 using an incandescent bulb or a halogen lamp forms a filament image that is a virtual image at the focal point, and the irradiation intensity may not be uniform. By providing the slits 12, the light is narrowed down so that the light source 9 becomes a point light source, and the shape of the irradiation pattern of the visible light 10 is finally shaped into a line or a wide band, and the irradiation intensity is increased. It can be even.

Note that, in the light source 9 of the light generation optical system, particularly when a light source 9 other than a laser is used, the light source 9 emits light in a wide wavelength region other than the wavelength region necessary for light sintering. It is preferable to block the excess wavelength region with a filter, a prism or the like. Specifically, it is preferable to block light having a wavelength of 300 nm or less and a wavelength of 700 nm or more.
This is because strong ultraviolet light having a wavelength of 300 nm or less may deteriorate the resin substrate. Further, the absorption coefficient of the fine particle ink is high, and it is absorbed too strongly only on the surface of the printed fine particle ink, so that sintering does not proceed sufficiently in the deep part, which causes a decrease in adhesion. For example, in an incandescent sphere that does not directly heat the nanoparticles, if the excess wavelength region is cut off with a filter, prism or the like and irradiated, sintering due to heating by infrared light can be suppressed, and damage to the substrate 14 can be prevented. Can be reduced.
On the other hand, the red and infrared heat rays having a wavelength of 700 nm or more may cause the substrate 14 to be unnecessarily heated and the wiring metal may diffuse into the substrate 14. In addition, when a filter that cuts light of 700 nm or more is inserted, it is preferable to use the light source 9 having a strong light intensity because light loss due to the filter is large.

Here, a modified example of the present embodiment will be described.
First, a wiring pattern may be printed on the substrate 14 cooled to room temperature or lower, and the substrate 14 may be irradiated with a laser. Also, as shown in FIG. 2, when the substrate 14 is transported using the rolls 1 and 4, the surface opposite to the surface on which the wiring pattern is printed is located on the substrate 14 at a position corresponding to the laser irradiation unit 5. Laser irradiation may be performed while contacting the cooling roll 3 rotated in accordance with the speed of the substrate 14. Thereby, when the cross-sectional area of the wiring is large, or when it is necessary to use the substrate 14 having poor heat resistance, the substrate material is cooled at the time of laser irradiation, thereby reducing damage to the substrate 14 in portions other than the wiring pattern portion. can do.
Instead of the cooling roll 3, the substrate may be brought into close contact with the cooling stage and cooled by heat conduction.
In addition, the substrate 14 may be cooled by applying cold air to the substrate 14. Alternatively, the conductive circuit may be formed while the entire substrate 14 is housed in a constant temperature layer and cooled.

The conductive circuit and conductive circuit device of this embodiment are formed and manufactured as follows.
As shown in FIG. 1, first, a long substrate 14 is placed on rolls 1 and 4 in order to be conveyed by winding.
Next, while transporting the substrate 14 using the rolls 1 and 4, the wiring pattern of the desired conductive circuit is transferred to the conductive pattern containing fine particles having an average particle diameter of 20 nm or less by the conventional printing machine 2. Printing is performed on the substrate 14 using a functional material.
And the light 10 which has a strip | belt-shaped irradiation pattern with respect to the said wiring pattern full width is irradiated from an irradiation optical system.
The conductive material printed on the substrate is sintered by the irradiation of the light 10 to produce a TAB tape or COF in which a wiring pattern of a desired conductive circuit is formed on the substrate 14.
Finally, a desired portion is cut out from the TAB tape or COF to manufacture a conductive circuit device.

According to this embodiment, the following effects can be obtained.
That is, by using a sintering method by light irradiation, the fine particles in the conductive material can be directly heated without heating and sintering the entire substrate 14, so that the temperature rise of the substrate 14 can be greatly reduced, and the heat resistance It is also possible to use a poor material as a substrate. In addition, a conductive circuit having sufficient conductivity can be formed without worrying about deterioration of conductivity due to residual resin or the like.
Furthermore, as compared with the case where a wiring pattern is drawn by light irradiation, a simple process of sintering the entire surface of the substrate 14 only by passing the substrate 14 on which the wiring pattern is printed in the laser irradiation unit 5 is sufficient. A conductive circuit can be formed at a formation speed.
As a result, the cost can be reduced, and the throughput can be greatly improved as compared with the prior art.
Note that the conductive circuit device manufactured by the conductive circuit forming method of the present embodiment is suitable as a circuit board, a wiring board, an electronic component, and a device, and particularly suitable for wiring of a printed wiring board or a semiconductor device.

  Next, the present invention will be described with reference to FIG. 1, which is an explanatory view of the conductive circuit forming method of the present embodiment.

(Average particle size)
First, a substrate 14 (hereinafter also referred to as a film 14), which is a long PI (polyimide) film having a thickness of 40 μm and a width of 35 mm, was placed on rolls 1 and 4 in order to be conveyed in the longitudinal direction. The delivery speed of the film 14 was approximately 2 m / min.
Next, a line and space wiring pattern having a line width of 5 μm and a line spacing of 5 μm and a solid film for adhesion evaluation were printed on the film 14 by the printer 2 using the flexographic printing method. Seven types of copper ink containing copper fine particles were used for the fine particle ink used for printing, and the average particle diameter was about 1 nm, 3 nm, 10 nm, 20 nm (above, Examples 1-4), 50 nm, 100 nm, 1 μm (above). Comparative Examples 1 to 3).
After printing, the film 10 on which the wiring pattern was printed was irradiated from a light source 9 with a laser 10 having an irradiation pattern spread in a band shape (substrate longitudinal direction 25 μm × substrate width direction 40 mm). As the light source 9, a YAG laser having a wavelength of 532 nm was used. The laser output was 1 kW. Here, the collimated laser 10 is guided by a combination of the plane mirror 8, the plano-concave cylindrical lens 7 and the Fθ lens 6, and the intensity of the laser 10 irradiated on the printing surface of the film 14 is determined by the center of the film 14. It was made uniform in the part and both ends in the width direction.
Further, the temperature of the film cooling roll 3 at the time of laser 10 irradiation was set to room temperature without being controlled.

Under the above conditions, the wiring pattern formed on the film 14 was sintered by laser 10 irradiation and evaluated for conductivity and adhesion.
About the said electrical conductivity, resistance was measured with the digital multimeter and the electrical conductivity was measured from line | wire width, the film thickness, and the measurement distance. About the said adhesiveness, it tested by the 90 degree peeling method based on JISC5012. FIG. 3 shows the measurement results.

As shown in FIG. 3, the conductivity and adhesion are different depending on the average particle diameter of the copper fine particles. Specifically, in the size (Examples 1 to 4) where the average particle diameter of the copper fine particles was 20 nm or less, generally good results were obtained in both conductivity and adhesion.
On the other hand, in the fine particle ink composed of particles having an average particle diameter exceeding 20 nm (Comparative Examples 1 to 3), the conductivity and adhesion were not improved even when the laser irradiation conditions were adjusted. In addition, the thing with an average particle diameter of 1 micrometer was not a metal film in the first place.

(Type of conductive material)
In Examples 5 to 7, except that gold, silver, and copper were used as the conductive materials of the fine particle ink, respectively, and the fine particle ink containing metal nanoparticles having a particle diameter of about 3 nm was used as the printing ink. In the same manner as in Examples 1 to 4, a wiring pattern was formed.
The evaluation results of conductivity and adhesion are shown in FIG. As shown in FIG. 4, good conductivity and adhesion were obtained with any metal.

(Substrate type)
In Examples 8 to 15, the substrate 14 is a PI film, an LCP (liquid crystal polymer resin) film, a PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) film, a PET (polyethylene terephthalate) film, or a PEN (polyethylene naphthalate). A wiring pattern was formed in the same manner as in Examples 1 to 4 except that a film and a glass substrate were used, respectively, and a fine particle ink containing metal nanoparticles having a particle diameter of about 3 nm was used as a printing ink. In addition, about PET and PEN (Examples 11-14), since there exists a possibility that a deformation | transformation of a film may arise when irradiation intensity | strength is increased in order to improve adhesiveness, the temperature of the film cooling roll 3 is changed from room temperature to 5 degreeC. Lowered.
The evaluation results of conductivity and adhesion are shown in FIG. As shown in FIG. 5, good conductivity and adhesion were obtained in any of the substrates.

(Light source type and wavelength)
In Examples 16 to 31, GaN-based LD (laser diode), YAG laser, Ar laser, He—Cd laser, KrF laser, GaN-based LED (light emitting diode), halogen lamp, arc lamp, flash lamp, mercury as light source 9 Examples 1 to 4 except that a lamp and an incandescent bulb were used, the wavelength was set in the range of 248 nm to 1064 nm, and the fine particle ink containing metal nanoparticles having a particle diameter of about 3 nm was used as the printing ink. Similarly to the above, a wiring pattern was formed. At that time, in the halogen lamp and the incandescent bulb, a band-pass filter 13 that transmits a wavelength region of 300 nm to 700 nm was inserted into the optical system, and a test was performed for each of the presence and absence. The evaluation results of conductivity and adhesion are shown in FIG.

First, the case of the light source using a laser (Examples 16 to 23) will be described.
As shown in FIG. 6, practical conductivity and adhesion were obtained with any light source.
In particular, in the case of GaN-based LD, YAG laser, and Ar laser, good conductivity and adhesion were obtained. In the case of a light source that does not have light with a wavelength of 300 nm or less and a wavelength of 700 nm or more, good conductivity and adhesion were obtained. The laser with a wavelength of 266 nm or less produced a practical conductivity and adhesion, although the film was clouded.

Next, a light source using a light emitting diode (Example 24) and lamps (Examples 25 to 31) will be described.
As shown in FIG. 6, practical conductivity and adhesion were obtained with any light source. In particular, for halogen lamps and incandescent bulbs (Examples 26 and 31), good conductivity and adhesion can be obtained by inserting a bandpass filter 13 that blocks light having a wavelength of 300 nm or less and a wavelength of 700 nm or more as an optical system. was gotten.

DESCRIPTION OF SYMBOLS 1 Sending side roll 2 Printing machine 3 Cooling roll 4 Winding side roll 5 Laser irradiation part 6 F (theta) lens 7 Cylindrical lens 8 Plane mirror 9 Laser light source 10 Irradiation light 11 Lens 12 Slit with shutter function 13 Optical filter 14 Substrate

Claims (15)

A method of forming a conductive circuit by printing a wiring pattern by cooling the substrate to room temperature or lower, and irradiating the wiring pattern with light.
For the printing of the wiring pattern, a conductive material containing fine particles having an average particle size of 20 nm or less is used,
The irradiation optical system that irradiates light to the wiring pattern includes a light generation optical system that generates light, and a shaping optical system that shapes the irradiation pattern of light so as to have a band shape,
By moving the irradiation pattern of the light irradiated by the irradiation optical system relative to the substrate so that the wiring pattern passes through the light, the entire width of the wiring pattern printed on the substrate is obtained. And irradiating the light with a conductive circuit. In a method of forming a conductive circuit by printing a wiring pattern on a substrate and irradiating the wiring pattern with light,
For the printing of the wiring pattern, a conductive material containing fine particles having an average particle size of 20 nm or less is used,
The irradiation optical system that irradiates light to the wiring pattern includes a light generation optical system that generates light, and a shaping optical system that shapes the irradiation pattern of light so as to have a band shape,
A roll cooled to room temperature or lower is brought into contact with the substrate, and the irradiation pattern of the light irradiated by the irradiation optical system is moved relative to the substrate so that the wiring pattern passes the light. By irradiating, the said light is irradiated over the wiring pattern full width printed on the said board | substrate, The conductive circuit formation method characterized by the above-mentioned. Conductive circuit forming method according to claim 1 or 2, wherein the light is visible light. The shaping optical system, the electrically conductive circuit forming method according to claims 1 to 3, characterized in that shaping so that uniform intensity distribution the light applied to the substrate. The fine particles, gold, silver, conductive circuit forming method according to any one of claims 1 to 4, characterized in that a metal containing any of copper. The fine particles, gold, silver, conductive circuit forming method according to any one of claims 1 to 4, characterized in that it comprises an oxide of a metal containing either copper. It said substrate is a polyimide substrate, a polyethylene terephthalate substrate, polyethylene naphthalate substrate, a conductive circuit forming method according to any one of claims 1 to 6, characterized in that either a liquid crystal polymer substrate. Wherein the light generating optical system of the light source, a conductive circuit forming method according to any one of claims 1 to 7, characterized in that it has a laser oscillator. 9. The conductive circuit forming method using an optical system according to claim 8 , wherein a solid-state laser is used as the laser oscillator. The method for forming a conductive circuit using an optical system according to claim 9 , wherein a nitride semiconductor laser diode or a YAG laser is used as the solid-state laser. The irradiation optical system, a cylindrical lens, one of Fθ lens, or a conductive circuit forming method according to any one of claims 1 to 10, characterized in that it comprises both. The said irradiation optical system contains the optical system which consists of any combination of a slit, a lens, a mirror, a shutter, an optical filter, and an optical fiber, or all combinations, The one in any one of Claim 1 thru | or 11 characterized by the above-mentioned. Conductive circuit formation method. Wherein the light generating optical system of the light source, light-emitting diodes, halogen lamps, arc lamps, flash lamps, mercury lamps, conductive circuit according to any one of claims 1 to 7, characterized in that either incandescent Forming method. The irradiation optical system, wavelength 300nm or less, and the conductive circuit forming method according to any one of claims 1 to 13, characterized in that it comprises an optical system to cut off more light wavelength 700 nm. It claims 1 to conductive circuit device having a conductive circuit made using conductive circuit forming method according to any one of 14.

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