JP2009004669A - Metal wiring board manufacturing method and metal wiring board formed using the same - Google Patents

Abstract

A method of manufacturing a metal wiring board that facilitates conversion from a metal precursor film formed by applying a metal fine particle-dispersed liquid onto a substrate to a metal film and improves the productivity of the metal wiring board, and uses the same An object of the present invention is to obtain a metal wiring board formed in this way.
A step of forming a metal precursor film on a substrate surface by applying a metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent to form a metal precursor film on the substrate surface; and a step of subjecting the metal precursor film to a heat treatment (S12), scanning the surface of the metal precursor coating with energy rays to metallize the metal precursor coating in the irradiated region of energy rays (S13), and the metal precursor in the non-irradiated region of energy rays Removing the body coating (S14).
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a metal wiring board using a metal fine particle dispersed liquid in which metal fine particles are dispersed in a solvent, and a metal wiring board formed using the method.

  In recent years, using ink or gravure using a metal ink obtained by dispersing fine particles of a metal, semiconductor, or oxide material in a solvent such as an organic solvent or water, or a fine particle dispersion liquid such as a metal paste. Attempts to manufacture electronic devices using printing techniques such as printing and screen printing are being studied. In particular, when manufacturing a large electronic device represented by a plasma display or the like, a conventional general manufacturing method using a vacuum apparatus and a photolithography technique using a mask, a resist, an exposure apparatus, etc. The manufacturing apparatus has become enormous in accordance with the size of the target electronic device, and accordingly, there has been a concern about an increase in equipment costs. Under such circumstances, the development of large-scale electronic devices by printing technology using fine particle dispersion liquid as ink has attracted particular attention.

  As a method for forming a wiring pattern using a fine particle dispersion liquid, for example, as shown in (Patent Document 1), it is composed of metal fine particles having an average particle diameter of 50 nm or less, and the metal fine particles are isolated by an organic substance. There is a method in which a metal fine particle-containing layer is formed on a support, and the metal fine particles are heated and fused by heating to a desired shape to form a conductive path.

In addition, as shown in (Patent Document 2), a base material having a conductive layer containing a conductive material and a photothermal conversion layer containing a photothermal conversion material that converts light energy into heat energy. Are irradiated with laser light, and at least a part of the conductive layer is baked using a photothermal conversion material to form the conductive layer.
JP 2004-039846 A Japanese Patent Laid-Open No. 2005-079901

  In the above (Patent Documents 1 and 2), a conductive material such as a metal is applied, dried and then irradiated with a high energy beam such as a laser, and the light is converted into heat, so that the metal fine particles are fused to form a conductive layer. To form. However, in any of the patent documents, a light-to-heat conversion material that converts light into heat or a light-to-heat conversion layer made of a light-to-heat conversion material is used to efficiently convert light into heat, thereby fusing metal fine particles. It is carried out. Therefore, it is necessary to apply a photothermal conversion material separately when applying the metal fine particles, or to mix the photothermal conversion material with the metal fine particles. There is a problem that the adhesive force between the conductive layer and the substrate material is deteriorated due to the presence of the photothermal conversion layer therebetween.

  The present invention has been made in view of the above, and facilitates the conversion from a metal precursor coating formed by applying a metal fine particle dispersion liquid to a substrate into a metal coating, thereby improving the productivity of the metal wiring board. It is an object of the present invention to obtain a metal wiring board manufacturing method to be improved and a metal wiring board formed using the same.

  In order to solve the above problems, the present invention applies a metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent to form a metal precursor film on the substrate surface, and heat-treats the metal precursor film. After the application, the surface of the metal precursor coating is scanned and irradiated with energy rays to metallize the metal precursor coating in the energy beam irradiation region, and the metal precursor coating in the non-irradiation region of the energy beam is removed. .

  According to the present invention, the metal fine particle dispersion liquid is formed on the substrate without adding the light / heat conversion material to the metal fine particle dispersion liquid or without providing the light / heat conversion layer in the vicinity of the metal precursor coating. Thus, a method for producing a metal wiring board can be obtained that facilitates conversion from a metal precursor film to a metal film and improves the productivity of the metal wiring board.

  According to a first aspect of the present invention, there is provided a method for producing a metal wiring substrate, wherein a metal fine particle dispersion liquid obtained by dispersing metal fine particles in a solvent is applied to a substrate surface to form a metal precursor film on the substrate surface, and the metal precursor film is heated The surface of the metal precursor coating is treated and scanned with energy rays to metalize the metal precursor coating in the energy beam irradiation area and remove the metal precursor coating in the energy beam non-irradiation area. The energy for metallizing the metal precursor coating when the energy beam is scanned and irradiated by performing a heat treatment so as to be in a state immediately before the fusion of the metal fine particles constituting the metal precursor coating occurs. The line input can be reduced, and the metal precursor film can be easily metallized.

  In the method for manufacturing a metal wiring board according to the second invention, in the first invention, the energy beam is a laser beam, and the energy amount of the energy beam for metallizing the metal precursor film can be easily controlled. Has the effect of becoming.

  A third method for manufacturing a metal wiring board is to apply a metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent to form a metal precursor film on the substrate surface, and to form a metal precursor film on the surface of the metal precursor film. The first energy beam and the second energy beam are scanned and irradiated to heat the metal precursor film in the irradiation region of the first energy beam, and the second energy beam in the irradiation region of the first energy beam. The metal precursor film in the irradiated region is metallized and the metal precursor film in the non-irradiated region of the second energy beam is removed, and the heat treatment of the metal precursor film and the metallization of the metal precursor film are almost completed. It has the effect that it can be done simultaneously.

  According to a fourth method for producing a metal wiring board, in the third invention, the energy density of the first energy line is smaller than the energy density of the second energy line. The heat treatment of the precursor film can be performed, and the metal precursor film can be easily metallized with the second energy beam.

  According to a fifth method of manufacturing a metal wiring board, in the third or fourth invention, the irradiation area of the first energy beam is wider than the irradiation area of the second energy beam. This has the effect of facilitating adjustment of the irradiation region of the line and the irradiation region of the second energy beam.

  In the third or fourth aspect of the manufacturing method of the sixth metal wiring board, the second energy ray irradiation region is included in the first energy ray irradiation region. The first energy beam irradiation region and the second energy beam irradiation region can be easily adjusted.

  According to a seventh method for manufacturing a metal wiring board, in the invention according to any one of the third to sixth inventions, a center in a direction perpendicular to the scanning direction of the irradiation region of the first energy beam, The center of the energy beam irradiation region in the direction perpendicular to the scanning direction is at substantially the same position, and adjustment of the first energy beam irradiation region and the second energy beam irradiation region is possible. It has the effect of facilitating.

  According to an eighth metal wiring board manufacturing method, in the invention according to any one of the third to seventh inventions, the center of the second energy beam irradiation region is the first energy beam irradiation region. It is located at the back of the scanning direction from the center, and has the effect that the adjustment range of the irradiation area of the first energy beam and the irradiation area of the second energy beam can be widened.

  According to a ninth method for manufacturing a metal wiring board, in the invention according to any one of the third to eighth inventions, the first energy line and the second energy line are laser beams. The first and second energy beams are scanned in the second step for metallizing the metal precursor coating in the energy beam irradiation region by irradiating the surface of the metal precursor coating with energy rays. It has an effect that the amount of energy to be irradiated can be easily controlled.

  In a tenth method of manufacturing a metal wiring substrate, a metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent is applied to the substrate surface to form a metal precursor film on the substrate surface, and the metal precursor film is subjected to ultraviolet irradiation treatment. The surface of the metal precursor coating is subjected to scanning irradiation with energy rays, the metal precursor coating in the irradiation region of the energy rays is metallized, and the metal precursor coating in the non-irradiation region of the energy rays is removed. The metal precursor film can be easily metallized without heat-treating the metal precursor film, and the productivity of the metal wiring board on a plastic substrate or the like that is not suitable for heat treatment is improved.

  In an eleventh method of manufacturing a metal wiring board, in the tenth invention, the energy beam is a laser beam, and the energy amount of the energy beam for metallizing the metal precursor film can be easily controlled. It has the action.

  In a twelfth metal wiring board manufacturing method, in the invention according to any one of the first to eleventh inventions, the metal fine particles have an average particle diameter of 20 nm or less. By scanning and irradiating the surface with energy rays, it is possible to reduce the input of energy rays for metallizing the metal precursor coating in the energy ray irradiation region, and the metal precursor coating can be easily metallized.

  The thirteenth metal wiring board is manufactured by the method for manufacturing a metal wiring board according to any one of the first to twelfth inventions, and high-density mounting with a fine wiring pattern can be made inexpensively. It has the action.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a process diagram showing a manufacturing process of the metal wiring board according to the first embodiment of the present invention. The metal wiring board manufacturing method of the present invention includes a metal fine particle dispersion liquid coating step (S11), a metal precursor coating heat treatment step (S12), and an energy beam scanning irradiation step (S13). And a step of cleaning and removing the non-irradiated region of the energy beam of the metal precursor coating (S14).

  The coating step of the metal fine particle dispersion liquid of S11 is a step of applying the metal fine particle dispersion liquid to the substrate surface to form a metal precursor film on the surface of the substrate, and the heat treatment step of S12 was formed on the substrate surface. In this step, the metal precursor film is subjected to heat treatment. The energy beam scanning irradiation step of S13 is a step of metallizing the metal precursor coating in the energy beam irradiation region by scanning and irradiating the surface of the metal precursor coating formed on the substrate surface with energy rays. The step of cleaning and removing the non-irradiated region of the energy beam is a step of cleaning and removing the metal precursor film in the region not irradiated with the energy beam. Through these steps, a metal wiring board is formed on the substrate surface, in which only the region metallized by energy beam scanning irradiation remains.

  Here, the metal fine particle-dispersed liquid is obtained by dispersing a surface of metal fine particles having a diameter of about 50 nm or less, desirably 20 nm or less, with a dispersion material made of an organic compound or the like in a liquid such as an organic solvent or water. Say something. Such metal fine particle dispersion liquids are commercially available for metals such as silver, gold, and copper. These metal fine particle-dispersed liquids have a feature that metal fine particles can be fused together to form a metal body by heating at a temperature considerably lower than the original melting point of the metal.

  The metal precursor film is a film formed by applying and forming a metal fine particle dispersion liquid on a substrate. Although this metal precursor coating depends on the application method and conditions of the metal fine particle dispersion liquid, a part of the solvent constituting the metal fine particle dispersion liquid evaporates, and the surface is mainly coated with a dispersion material composed of an organic compound or the like. Made of fine metal particles. When such a coating is heated to a predetermined temperature or higher, the dispersion material composed of an organic compound or the like is removed from the surface of the metal fine particles, and the active metal fine particles are fused together to form a metal body. In particular, it is known that when the diameter of the metal fine particles is reduced, the temperature at which the metal fine particles are fused to each other is significantly lower than the melting point inherent to the metal.

  Here, the detail of the formation method of the metal wiring board by Embodiment 1 of this invention is demonstrated below. 2-7 is a figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention.

  Here, a glass substrate is used as the substrate 1. First, the fine metal particle dispersion liquid 2 is applied to the cleaned glass substrate 1 by spin coating. Specifically, as shown in FIG. 2, after the metal fine particle dispersion liquid 2 is dropped on the entire surface of the glass substrate 1 using a pipette 3 on the surface of the glass substrate 1 set in a spin coater (not shown), the glass substrate 1 is A film made of the metal fine particle dispersion liquid 2 was formed on the surface of the glass substrate 1 by holding at a predetermined rotation speed for a predetermined time, for example, at a rotation speed of 1000 rotations / minute for 30 seconds. When spin coating is performed after the metal fine particle dispersion liquid 2 is dropped on the glass substrate 1, excess metal fine particle dispersion liquid 2 is scattered and a part of the solvent of the metal fine particle dispersion liquid 2 remaining on the surface of the glass substrate 1 is evaporated. A reddish brown film is formed on the surface of the glass substrate 1. As shown in FIG. 3, the metal fine particle dispersion liquid 2 dropped onto the glass substrate 1 is spin-coated, and the film remaining on the surface of the glass substrate 1 is referred to as a metal precursor film 4.

  Next, the metal precursor coating 4 formed on the surface of the glass substrate 1 is subjected to heat treatment. In the first embodiment, as shown in FIG. 4, heat treatment is performed by placing the glass substrate 1 on which the metal precursor film 4 is formed on a heated hot plate 5. Here, heat treatment is performed in which the glass substrate 1 is placed on the hot plate 5 whose temperature is set to 250 ° C. for 50 seconds. As shown in FIG. 5, when the metal precursor coating 4 is subjected to heat treatment, the color of the metal precursor coating 4 becomes darker than before heating.

  Next, the surface of the metal precursor film 4 that has been subjected to the heat treatment is scanned with energy rays. FIG. 6 is a diagram showing a schematic configuration diagram of an energy beam irradiation scanning device. In the first embodiment, a laser beam using a semiconductor laser is used as the energy beam.

  In FIG. 6, reference numeral 6 denotes an irradiation scanning device that performs energy beam scanning irradiation, 7 denotes a substrate holder portion on which the substrate 1 on which the metal precursor film 4 is formed is mounted, 8 denotes a semiconductor laser serving as a laser light source, and 9 denotes laser light. The emission unit 10 is a control unit that controls the operation of the substrate holder unit 7 and the laser beam emission unit 9, 11 is a substrate holder that holds and fixes the substrate 1 on which the metal precursor coating 4 is formed, and 12 is a signal from the control unit 10. , A drive system for driving the substrate holder 11 in the xyz triaxial direction with respect to the laser light emitted from the laser light emitting unit 9, 13 an optical system for shaping the light emitted from the laser light source 8, 14 Is a metal coating, and 15 is an unirradiated region of the laser beam. Here, the substrate holder 11 and the drive system 12 constitute a substrate holder portion 7, and the laser light source 8 and the optical system 13 constitute a laser light emitting portion 9. In FIG. 6, the directions orthogonal to each other in the upper surface of the substrate holder 11 (substrate 1) are defined as the x direction and the y direction, and the directions orthogonal to both the x direction and the y direction (emitted from the laser light emitting unit 9). The direction of the laser beam to be emitted) is the z direction.

  In the first embodiment, a semiconductor laser having a wavelength of 670 nm and an output of 800 mW is used as the light source. The optical system 13 includes a collimator lens, a prism, a condenser lens, and the like so that the light beam emitted from the laser light source 8 is focused on the surface of the glass substrate 1 fixed on the substrate holder 11. It is configured. The laser light source 8 operates according to a signal from the control unit 10.

  Here, the operation of the energy beam irradiation scanning device 6 will be described. First, the glass substrate 1 on which the metal precursor film 4 is formed is set on the substrate holder 11. The glass substrate 1 can be set on the substrate holder 11 by, for example, fixing the back surface of the glass substrate 1 with a vacuum chuck. The substrate holder 11 is moved by a signal from the control unit 10 in the xyz direction with respect to the laser beam emission direction.

  Next, the laser light source 8 is driven by a signal from the control unit 10 and emits a laser beam. The emitted laser beam is shaped by passing through the optical system 13 and irradiated onto the surface of the glass substrate 1 fixed to the substrate holder 11. The position of the substrate holder 11 in the z-axis direction is controlled based on a signal from the control unit 10 so that the laser beam irradiated on the surface of the glass substrate 1 is focused on the surface of the glass substrate 1. In this way, the laser beam is applied to the surface of the metal precursor film 4 formed on the surface of the glass substrate 1. The irradiated laser beam is partially reflected, partially transmitted, and partially absorbed by the metal precursor coating 4. Due to the action of the laser beam on the metal precursor coating 4, a part of the light becomes thermal energy, and the laser beam irradiation portion of the metal precursor coating 4 is heated.

  The metal precursor film 4 is a film made of a dispersion of metal fine particles. When the metal precursor film is heated and exceeds a predetermined temperature, the metal fine particles constituting the metal precursor film 4 are fused to each other. Proceeding and substantially converting the metal particulates into a continuous metal coating 14. As described above, the surface of the metal precursor coating 4 is irradiated with the laser beam, and the laser beam irradiation portion is heated, whereby the minute metal coating 14 is formed.

  On the other hand, since the substrate holder 11 operates in the xy direction based on a signal from the control unit 10, it is possible to irradiate a laser beam to any position of the metal precursor coating 4. That is, laser beam irradiation scanning can be performed by irradiating the laser beam while moving the glass substrate 1.

  As described above, when the metal precursor coating 4 is irradiated with the laser beam to heat the metal precursor coating 4, the metal precursor coating 4 is converted into the metal coating 14. This means that the region through which the laser beam has passed on the surface of the metal precursor film 4 can be converted into the metal film 14, and thus, a linear metal film 14 is formed on the glass substrate 1. Is done. In the case where a continuous line (wiring) is formed as the linear metal film 14, the laser beam may be continuously irradiated and scanned, but the input power of the laser light source 8 is reduced or cut off, or By performing a treatment such as providing a light-shielding device between the laser beam and the metal precursor coating 4, an intermittent line other than the continuous line can be easily formed.

  In this way, the metal precursor coating 4 becomes a metal coating 14 by scanning and irradiating the metal precursor coating 4 with a laser beam, and a metal pattern is formed. However, the unirradiated region 15 of the laser beam is the metal precursor film 4. Since this metal precursor film 4 is an aggregate of metal fine particles, it is an unstable substance and is preferably removed for use as the metal wiring board 16. The removal of the metal precursor film 4 in the unirradiated region 15 of the laser beam can be performed by immersing the glass substrate 1 in the solvent used in the metal fine particle dispersion liquid 2. This is because the metal precursor film 4 remaining on the glass substrate 1 swells by being immersed in the solvent used in the metal fine particle dispersion liquid 2 and can be easily removed. If it is difficult to remove, an ultrasonic cleaner may be used. Finally, as shown in FIG. 7, the metal wiring board 16 is formed on the glass substrate 1 by rinsing with the same solvent used for the metal fine particle dispersion liquid 2.

  Next, in order to investigate the effect of the heat treatment after the formation of the metal precursor coating 4 of the first embodiment, the following test sample is prepared, and the result of examining the electrical resistance of the wiring is shown.

  FIG. 8 is a diagram showing a wiring pattern of a test sample according to the first embodiment of the present invention. Here, 17 is a wiring pattern, 18 is a linear portion of the wiring pattern, and 19 is four terminal portions for measuring the electrical resistance of the linear portion 18. The wiring pattern 17 as shown in FIG. 8 is formed by the manufacturing method as described above, but the terminal portion 19 can be formed by performing irradiation scanning so that the laser beams overlap. Here, the linear portion 18 of the wiring pattern 17 was formed while changing the irradiation scanning speed. Below, the detail of the manufacturing method of the metal wiring board which has the wiring pattern of FIG. 8 is demonstrated, and the measurement result about the electrical resistance of the wiring is shown after that.

  A glass substrate was used as the substrate 1, and Ag1T (trade name) manufactured by ULVAC Materials was used as the metal fine particle dispersion liquid 2. After the metal fine particle dispersion liquid 2 is applied onto the glass substrate 1 by spin coating to form the metal precursor film 4, the heat treatment of the metal precursor film 4 is set so that the surface temperature of the glass substrate becomes 250 ° C. The specimen subjected to the heat treatment by placing it on the hot plate for 50 seconds is used as the test body of the first embodiment. A plurality of test bodies of Embodiment 1 subjected to such heat treatment were formed.

  Further, as a control sample for the experiment, the glass substrate in which the metal precursor film 4 is not subjected to the heat treatment after the metal precursor film 4 is formed on the glass substrate is used as in the test sample of the first embodiment. A plurality of test specimens were formed.

  Next, using the laser beam irradiation scanning device 6 described above on the glass substrate 1 of the first embodiment and the glass substrate 1 of the comparative example 1, the metal precursor coating 4 is irradiated with the laser beam and the wiring shown in FIG. Pattern 17 was formed. At this time, the scanning speed of laser beam irradiation (moving speed in the X direction of the substrate holder 11) was changed for each specimen. Finally, the laser beam unirradiated region 15 of the metal precursor coating 4 is immersed and removed in toluene, which is the solvent of the metal fine particle dispersion liquid 2, and rinsed to prepare the test body of Embodiment 1 and the test body of Comparative Example 1. did. And the electrical resistance between each terminal part 19 was measured. (Table 1) is a table showing measurement results of electrical resistance for the test bodies of Embodiment 1 and Comparative Example 1.

  As shown in (Table 1), in the test body of the first embodiment, even when the laser beam irradiation scanning speed is increased, the electric resistance of the linear portion 18 is substantially 7.8Ω. On the other hand, in the test body of Comparative Example 1, when the irradiation scanning speed of the laser beam was increased, the electric resistance of the linear portion 18 showed a tendency to increase, and eventually the electric resistance increased rapidly.

  This is because, even if the irradiation scanning speed of the test body is increased, in the test body of the first embodiment, the metal precursor film 4 is converted to the metal film 14 by the laser beam irradiation, that is, the metal precursor film 4 is formed. It is considered that the electric resistance is stable because the fusion of the metal fine particles occurs regardless of the irradiation scanning speed of the specimen.

  On the other hand, in the test body of Comparative Example 1, when the irradiation scanning speed of the laser beam is increased, the metal fine particle forming the metal precursor coating 4 is converted from the metal precursor coating 4 to the metal coating 14 by the laser beam irradiation. This is considered to be an incomplete fusion, which appears as a tendency to increase the electrical resistance of the straight portion 18.

  Actually, when the surface of the test specimen is observed, a smooth metal film 14 is formed regardless of the irradiation scanning speed in the test specimen of Embodiment 1, but in the test specimen of Comparative Example 1, the irradiation scanning speed is high. It was confirmed that the smoothness was lost as the speed increased. As described above, in the first embodiment in which the heat treatment is performed before the metal precursor coating 4 is irradiated with the laser beam, Comparative Example 1 in which no processing is performed before the metal precursor coating 4 is irradiated with the laser beam. In comparison, it is shown that the smooth metal film 14 can be formed even if the irradiation scanning speed of the laser beam is increased. This is because when the metal precursor film 4 is converted into the metal film 14 by heating, the metal film precursor is preliminarily heat-treated, thereby converting the heat, that is, between the metal fine particles constituting the metal precursor film 4. This is considered to be due to the state in which such fusion is likely to occur.

  In the first embodiment, the heat treatment is performed under the condition that the metal precursor film 4 is heated at 250 ° C. for 50 seconds. This condition is that the film thickness of the metal precursor film 4 and the metal precursor film 4 are changed. It varies depending on the type and diameter of the metal of the metal fine particles to be formed, the dispersant covering the periphery of the individual metal fine particles, etc., and the optimum conditions may be determined in consideration of these. In this case, it should be noted that it is necessary to stop the heat treatment of the metal precursor coating 4 immediately before the fusion of the metal fine particles occurs. After the wiring pattern is formed on the metal precursor coating 4 by laser beam irradiation scanning, the laser precursor non-irradiated region 15 of the metal precursor coating 4 is cleaned and removed with a solvent of the metal fine particle dispersion liquid. When heat treatment is performed under conditions that cause fusion, the film has already been metallized to form a film, which cannot be removed by washing. As a result, an unintended pattern is formed, causing a problem such as a short circuit between the intended wiring patterns. Thus, heat treatment under conditions that cause fusion of metal fine particles is not desirable.

  Moreover, in this Embodiment 1, although the metal precursor film | membrane 4 was metallized by laser beam irradiation by another process after the heat processing process of the metal precursor film | membrane 4, the heat processing of the metal precursor film | membrane 4 was carried out. The metal precursor film 4 may be metallized by laser beam irradiation while performing. However, the metallization of the metal precursor coating 4 by heating is determined by the heating temperature and the heating time. Therefore, depending on the heat treatment conditions, for example, when the processing time for forming a metal film by laser beam irradiation, such as forming a complicated wiring pattern, becomes long, the metal precursor is scanned during laser beam irradiation scanning. Care must be taken since the conversion from the body coating 4 to the metal coating may proceed.

  Furthermore, in the first embodiment, the heat treatment of the metal precursor film 4 is performed using the hot plate 5, but this is easy to observe the surface change when changing from the metal precursor film 4 to the metal film 14. Therefore, it is used. Therefore, the heat treatment of the metal precursor coating 4 may use heating means such as an electric furnace, an oven, and an infrared heating furnace in addition to the hot plate 5.

  In the first embodiment, a glass substrate is used as the substrate 1. However, the present invention is not limited to this, and a ceramic substrate, a glass epoxy substrate, a flexible polyimide substrate or the like generally used for a wiring substrate is used. It may be used.

  Furthermore, as shown in the first embodiment, the laser output is reduced while adjusting the scanning speed, that is, the heating time, instead of shortening the irradiation time of the laser beam by increasing the scanning speed, that is, the heating time. May be weakened. By doing in this way, it is effective for formation of a metal wiring board with a board inferior in heat resistance.

  In the first embodiment, the thickness of the wiring is reduced to about 0.5 μm. However, the thickness of the wiring portion can be increased by applying a plating film or the like to the wiring.

  As described above, in the first embodiment, the metal precursor film 4 is formed from the metal fine particle dispersion liquid 2 on the substrate 1, and the metal precursor film 4 is heat-treated under the condition that no fusion between the metal fine particles occurs. Later, the metal film 14 is formed by scanning and irradiating an energy beam such as a laser beam, so that the metal wiring can be formed without using an expensive apparatus such as photolithography. Further, an arbitrary wiring pattern 17 can be formed on the metal wiring having a fine wiring width based on the output of the laser beam from the control device without using a mold such as a photomask.

  Further, the wiring pattern 17 having high adhesion to the substrate 1 can be obtained without mixing a photothermal conversion material into the metal fine particle dispersion liquid 2 or providing a photothermal conversion layer between the substrate 1 and the metal precursor coating 4. Therefore, the processing steps can be simplified as compared with the conventional metal wiring manufacturing method. Furthermore, the energy beam required for metallization of the metal precursor coating can be reduced during the energy beam scanning irradiation, and the energy beam output device (scanning irradiation device) can be downsized. In addition, the energy beam irradiation scanning speed can be increased by reducing the energy beam output without reducing the output of the energy beam, thereby shortening the manufacturing time of the metal wiring board and improving the productivity.

  Furthermore, since the metal precursor coating does not change to metal throughout the process and remains as the metal precursor coating, conventional methods can be used to remove the non-irradiated portions of the energy rays on the metal precursor coating. Therefore, the manufacturing method of the present invention can be easily introduced into a conventional metal wiring board manufacturing process.

(Embodiment 2)
In the heat treatment step of Embodiment 1, the case where the treatment is performed using a hot plate is shown. By performing the heat treatment process on the metal precursor film as in the first embodiment, the irradiation scanning speed can be increased in the energy beam scanning irradiation process of the next process, which is effective for manufacturing the metal wiring board. There was a need for a heat treatment step. Therefore, in the second embodiment, a case will be described in which the heat treatment process is performed by irradiation with energy rays, and the process is further simplified as compared with the first embodiment.

  The manufacturing method of the metal wiring board according to the second embodiment is the same as that shown in the process chart shown in FIG. However, the point that the heat treatment process of S12 heat-treats the metal precursor film by the first energy ray irradiation is different from the case of the first embodiment. At this time, in the energy beam scanning irradiation step of S13, the surface of the metal precursor film formed on the substrate surface is scanned and irradiated with the second energy beam, and the metal precursor film in the region irradiated with the second energy beam. Metallize. Other steps are the same as those in the first embodiment, and the description thereof is omitted.

  Next, a method for manufacturing a metal wiring board according to the second embodiment of the present invention will be described with a specific example. First, as the metal fine particle dispersion liquid, NPS-J (trade name) manufactured by Harima Kasei Co., Ltd., whose metal is silver, was used. The cleaned glass substrate was set on a spin coater, and the metal fine particle dispersion liquid was applied by spin coating. That is, after the metal fine particle dispersion liquid is dropped on the entire surface of the glass substrate using a pipette, the glass substrate is held at a predetermined rotation speed for a predetermined time, for example, at a rotation speed of 1000 rotations / minute for 30 seconds. A film made of a metal fine particle dispersion liquid on the surface of the substrate, that is, a metal precursor film 4 was formed.

  Next, in the second embodiment, the heat treatment of the metal precursor film is performed by the irradiation of the first energy beam, but the metal of the metal film precursor subjected to the heat treatment by the irradiation of the second energy beam almost simultaneously. A film is formed.

  FIG. 9 is a diagram showing a schematic configuration of a laser beam irradiation scanning apparatus according to the second embodiment of the present invention. In FIG. 9, reference numeral 20 denotes a first laser beam emitting unit, 21 denotes a second laser beam emitting unit, 22 denotes a first laser light source, 23 denotes a second laser light source, and 24 denotes first and second lasers. It is an optical system that shapes light beams emitted from the light sources 22 and 23 and guides them to the first and second laser beam emitting units 20 and 21, respectively. Note that the same components as those in the laser beam irradiation scanning apparatus of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In FIG. 9, the directions orthogonal to each other in the upper surface of the substrate holder 11 (substrate 1) are defined as the x direction and the y direction, and the direction perpendicular to both the x direction and the y direction (second laser light emitting portion) The direction of the laser beam emitted from 21 is the z direction.

  In the second embodiment, a semiconductor laser having a wavelength of 830 nm and an output of 500 mW is used as the first laser light source 22, and a second semiconductor laser having a wavelength of 670 nm and an output of 800 mW is used as the second laser light source 23. The optical system 24 includes a collimator lens, a prism, a condensing lens, and the like, and the laser beam emitted from the first and second laser light sources 22 and 23 is fixed on the substrate holder 11. It is configured to focus on the surface. Further, the first and second laser light sources 22 and 23 operate according to signals from the control unit 10.

  Next, the operation of the laser beam irradiation scanning device 6 having such a configuration will be described. First, the substrate 1 on which the metal precursor film 4 is formed in S11 is set on the substrate holder 11. In setting the substrate 1, the back surface of the substrate is fixed by a technique such as a vacuum chuck. The substrate holder 11 is moved by a signal from the control unit 10 in the xyz direction with respect to the emission direction of the second laser beam emitted from the second laser light emission unit 21.

  The first laser light source 22 is driven by a signal from the control unit 10 and a first laser beam is emitted. The emitted first laser beam passes through the optical system 24 so that the beam is shaped and irradiated onto the surface of the substrate 1 fixed to the substrate holder 11. The substrate holder 11 moves in the z-axis direction based on the control system signal so that the first laser beam applied to the surface of the substrate 1 is focused on the substrate surface. In this way, the first laser beam is irradiated onto the surface of the metal precursor coating 4 formed on the surface of the substrate 1, and the irradiated first laser beam is partially reflected and partially irradiated. Permeates and is partially absorbed by the metal precursor coating 4. Thus, due to the action of the first laser beam on the metal precursor coating 4, a part of the light becomes thermal energy, and the irradiation portion of the first laser beam of the metal precursor coating 4 is heated. Become.

  The heat treatment for the metal precursor film 4 is performed by irradiation with the first laser beam, but the heat treatment conditions such as the irradiation region of the first laser beam and irradiation energy are also described in the first embodiment. As described above, since the thickness varies depending on the film thickness of the metal precursor film 4, the type and diameter of the metal particles constituting the metal precursor film 4, the dispersant covering the periphery of the individual metal particles, etc. What is necessary is just to determine the optimal conditions in consideration of What should be noted in this case is that the heat treatment of the metal precursor coating 4 needs to be stopped immediately before the fusion of the metal fine particles occurs. After the metal precursor film 4 is converted into the metal film 14 by the irradiation scanning of the second laser beam, the unirradiated area 15 of the second laser beam on the metal precursor film 4 is washed and removed with a solvent of the metal fine particle dispersion liquid. However, when heat treatment is performed under conditions that cause fusion of the metal fine particles, in the state where the unirradiated region 15 of the second laser beam has already become a metallized film, cleaning and removal are performed. Because it becomes impossible. As a result, an unintended pattern is formed on the substrate 1 and causes a problem such as a short circuit between the intended wiring patterns. It is necessary to stop.

  Almost simultaneously with the irradiation of the first laser beam onto the metal precursor coating 4, the second laser light source 23 is driven by a signal from the control unit 10 to emit the second laser beam. The emitted second laser beam passes through the optical system 24, so that the beam is shaped and irradiated onto the surface of the substrate 1 fixed to the substrate holder 11. The substrate holder 11 operates in the z-axis direction based on a signal from the control unit 10 so that the second laser beam irradiated on the surface of the substrate 1 is focused on the substrate surface. In this way, the second laser beam is irradiated onto the surface of the metal precursor coating 4 formed on the surface of the substrate 1, and the irradiated second laser beam is partially reflected and partially reflected. Permeates and is partially absorbed by the metal precursor coating 4. Thus, due to the action of the second laser beam on the metal precursor coating 4, part of the light becomes thermal energy, and the irradiation portion of the second laser beam on the metal precursor coating 4 is heated. become.

  Here, the metal precursor film 4 is a film made of a dispersion of metal fine particles. When the metal precursor film 4 is heated and exceeds a predetermined temperature, the metal fine particles constituting the metal precursor film 4 are mutually connected. As the fusion proceeds, the metal fine particles are substantially converted into a continuous metal coating 14. In this way, the surface of the metal precursor coating 4 is irradiated with the second laser beam, and the irradiation portion of the second laser beam is heated, so that the region of the minute metal coating 14 is formed.

  On the other hand, since the substrate holder 11 operates in the xy direction based on the signal from the control unit 10 by the drive system 12, it is possible to irradiate the first and second laser beams to any position of the metal precursor coating 4. It becomes. That is, irradiation scanning with the first and second laser beams that irradiate the first and second laser beams while moving the substrate 1 can be performed.

  Thus, by irradiating the metal precursor film 4 with the first laser beam, the metal precursor film 4 is subjected to a heat treatment so that the metal precursor film 4 is easily converted into the metal film 14, that is, The state immediately before the fusion of the metal fine particles occurs. This is because when the first laser beam is irradiated and scanned on the surface of the metal precursor film 4, the metal precursor film 4 in the region through which the first laser beam has passed is easily converted into the metal film 14. That is, the heat treatment region of the linear metal precursor film 4 is formed. In the case where a continuous line (wiring) is formed as the linear metal film 14, the laser beam may be continuously irradiated and scanned. However, the input power of the first and second laser light sources 22 and 23 is sufficient. Intermittent lines other than continuous lines can be easily formed by reducing or reducing the input or by performing a process such as providing a light shielding device between the laser beam and the metal precursor film 4.

  Moreover, when the metal precursor film 4 is heated by irradiating the metal precursor film 4 with the second laser beam, the metal precursor film 4 is converted into the metal film 14. When the second laser beam is irradiated and scanned above, the region through which the second laser beam has passed can be converted into the metal film 14. By doing so, the linear metal film 14 is formed on the substrate 1. Will be formed on top. If the linear metal film 14 is continuous, the second laser beam may be continuously irradiated and scanned. However, the input power of the second laser light source 23 is reduced, the input is turned off, or the second laser beam is turned off. By performing a treatment such as providing a light-shielding device between the laser beam and the metal precursor coating 4, an intermittent line other than the continuous line can be easily formed.

  In this way, the metal precursor coating 4 is changed to the metal coating 14 by scanning and irradiating the metal precursor coating 4 with the first and second laser beams, and the metal wiring board 16 is formed. However, the unirradiated region 15 of the second laser beam is the metal precursor film 4. Since this metal precursor film 4 is an aggregate of metal fine particles, it is an unstable substance and is preferably removed for use as the metal wiring board 16. The removal of the metal precursor film 4 in the unirradiated region 15 of the second laser beam can be performed by immersing the substrate in the solvent used in the metal fine particle dispersion liquid 2. This is because the metal precursor coating 4 remaining on the substrate 1 swells by being immersed in the solvent used in the metal fine particle dispersion liquid 2 and can be easily removed. If it is difficult to remove, an ultrasonic cleaner or the like may be used. Finally, the metal wiring board 16 is formed on the substrate 1 by rinsing with the same solvent as that used for the metal fine particle dispersion liquid 2.

  As described above, the metal fine particle-dispersed liquid 2 is applied to the substrate 1 to form the metal wiring substrate 16. In order to examine the effect of the heat treatment after the formation of the metal precursor film 4 of the second embodiment, The following test samples are prepared, and the results of examining the electrical resistance of the wiring pattern 17 are shown. Note that the wiring pattern 17 of the test sample uses the same wiring pattern 17 as in FIG. 8 of the first embodiment, and the laser beam irradiation scanning speed is changed for the straight portion 18 of the wiring pattern 17 in the same manner as in the first embodiment. Formed while.

  A glass substrate was used for the substrate 1, and NPS-J (trade name) manufactured by Harima Kasei Co., Ltd. was used for the metal fine particle dispersion liquid 2. The metal fine particle dispersion liquid 2 was applied onto a glass substrate by spin coating to form a plurality of metal precursor films 4 on the glass substrate.

  Next, the substrate 1 on which the metal precursor coating 4 was formed was irradiated with a laser beam on the metal precursor coating 4 using the laser beam irradiation scanning device 6 of FIG. 9 to form a wiring pattern 17 shown in FIG. . At this time, the scanning speed of laser beam irradiation (moving speed in the X direction of the substrate holder) was changed for each specimen. However, here, as shown in FIG. 9, after the metal precursor coating 4 is heat-treated by irradiation with the first laser beam, the metal precursor coating 4 is applied to the metal coating by irradiation with the second laser beam. Then, the wiring pattern 17 was formed. Finally, the second laser beam non-irradiated region 15 of the metal precursor coating 4 was immersed and removed in tetradecane, which is the solvent of the metal fine particle dispersion liquid 2, and rinsed to prepare a test body of Embodiment 2.

  As a control sample for the experiment, similarly to the specimen of the second embodiment, the metal precursor film 4 is formed on the glass substrate, and the irradiation scanning speed of the laser beam irradiation using the laser beam irradiation scanning device 6 described above. The wiring pattern 17 was formed by irradiating a laser beam while changing the (moving speed of the substrate holder in the X direction). However, in Comparative Example 2, the metal precursor coating is performed by irradiating only the second laser beam without irradiating the first laser beam, that is, without subjecting the metal precursor coating 4 to heat treatment. 4 was converted to metal to form a wiring pattern 17. Finally, as in the second embodiment, the second laser beam unirradiated region 15 of the metal precursor coating 4 is dipped and removed in tetradecane, which is the solvent of the metal fine particle dispersion liquid 2, and then rinsed and subjected to the comparative example 2. A test specimen was prepared. And the electrical resistance between each terminal part 19 of the test body of these Embodiment 2 and the comparative example 2 was measured. (Table 2) is a table | surface which shows the measurement result of the electrical resistance about the test body by Embodiment 2 and a comparative example.

  As shown in (Table 2), in the specimen of the second embodiment, even when the irradiation scanning speeds of the first and second laser beams are increased, the electric resistance of the linear portion is approximately 4.2Ω. It is constant. On the other hand, in the test body of Comparative Example 2, when the irradiation scanning speed of the second laser beam is increased, the electric resistance of the straight line portion tends to increase, and finally the electric resistance rapidly increases. It became.

  This is because, even if the scanning speed of the specimen is increased, in the specimen of the second embodiment, the metal precursor film 4 is converted to the metal film 14 by irradiation with the second laser beam, that is, the metal precursor film 4 is removed. It is considered that the electrical resistance is stable because the fusion between the formed metal fine particles occurs regardless of the scanning speed of the specimen.

  On the other hand, in the test body of Comparative Example 2, when the irradiation scanning speed of the second laser beam is increased, the metal precursor coating 4 is converted to the metal coating 14 by the second laser beam irradiation, that is, the metal precursor coating 4. It is considered that the fusion of the metal fine particles forming the metal becomes incomplete, which appears as a tendency of an increase in the electric resistance of the straight portion.

  Actually, when the surface of the test specimen is observed, a smooth metal film 14 is formed regardless of the scanning speed in the test specimen of the second embodiment. However, in the test specimen of Comparative Example 2, the scanning speed is increased. It was confirmed that the smoothness was lost. As described above, in the second embodiment in which the metal precursor film 4 is irradiated with the first laser beam before the metal precursor film 4 is irradiated with the second laser beam, the metal precursor film 4 is heated. It is shown that a smooth metal film 14 can be formed even if the irradiation scanning speed of the second laser beam is increased as compared with Comparative Example 2 in which no treatment is performed before the second laser beam is irradiated. This is because, when the metal precursor film 4 is converted into the metal film 14 by heating, the metal precursor film 4 is preliminarily heat-treated to convert, that is, heat between the metal fine particles constituting the metal precursor film 4. This is considered to be due to the fact that fusion due to the above is likely to occur.

  In the second embodiment, the heat treatment of the metal precursor film by the first laser beam is performed using a semiconductor laser having a wavelength of 830 nm and an output of 500 mW. This condition is applied to the first and second lasers. Changes depending on the irradiation scanning speed of the light beam, the film thickness of the metal precursor coating 4, the type of metal of the metal fine particles constituting the metal precursor coating 4, the diameter of the metal fine particles, the dispersant covering the periphery of the individual metal fine particles, etc. Therefore, the optimum conditions may be determined in consideration of these. What should be noted in this case is that the heat treatment of the metal precursor coating 4 needs to be stopped immediately before the fusion of the metal fine particles occurs. After the wiring pattern 17 is formed on the metal precursor film 4 by scanning with irradiation of the second laser beam, the unirradiated region 15 of the metal precursor film 4 that has not been irradiated with the second laser beam is cleaned and removed. Although it is carried out with a solvent, when the heat treatment is performed under such conditions that the metal fine particles are fused, the film is already metallized and cannot be removed by washing. As a result, an unintended metal coating 14 is formed, causing problems such as a short circuit between the intended wiring patterns 17. Thus, the heat treatment with the first laser beam under conditions that cause fusion of the metal fine particles is not desirable.

  Further, the heat treatment of the metal precursor coating 4 is performed with the first laser beam, and the metal precursor coating 4 is converted into the metal coating 14 with the second laser beam, so that the energy density of the first laser beam. Needless to say, must be smaller than the energy density of the second laser beam. This is because, when the energy density of the first laser beam is higher than the density of the second energy beam, the irradiation of the second energy beam does not cause a change from the heat-treated metal precursor coating 4 to the metal. Because there is no.

  In addition, the metal precursor coating 4 is heat-treated by irradiation with the first laser beam, and the metal precursor coating 4 is subsequently metallized by irradiation with the second laser beam. When the irradiation region is wider than the irradiation region of the second laser beam, the positioning of the irradiation position of the first laser beam and the irradiation position of the second laser beam is easy to control. is there. At least the irradiation region of the first laser beam and the irradiation region of the second laser beam may be the same, but the heat treatment region by the first laser beam is widened and the second laser beam is irradiated. It is more effective to narrow the metallized region by light because the control during the laser beam irradiation scanning becomes easier. That is, if the irradiation region of the second laser beam is included in the first laser beam, it becomes easier to control.

  Further, in the second embodiment, a laser beam is used as the first energy beam. However, the first energy beam is not limited to the laser beam, and the metal precursor coating 4 can be heated to a predetermined temperature. Any device that can add energy may be used. For example, an electron beam or an infrared light source may be used. However, since it is an application for performing metal wiring, it is often desirable that the irradiation region of the first energy beam is narrow. From this viewpoint, the light emitted from the first laser light source 22 can be easily transmitted by the optical system 24. The laser light source that can be narrowed down is excellent in that it is easy to use. In addition, the laser beam is easy to select because it has a wide selection range such as a semiconductor laser and a gas laser and there are many types of wavelengths of the laser beam. The wavelength of the laser beam is selected by selecting a wavelength at which the metal precursor film 4 has a large absorption. The light beam emitted from the first laser light source 22 is efficiently converted into heat on the metal precursor film 4. And can be used effectively for heat treatment.

  Furthermore, adjustment and control of the irradiation energy of the first and second laser beams is performed when the center of the irradiation region of the first laser beam and the center of the irradiation region of the second laser beam are substantially the same position. easy. This is because the energy distribution of the laser beam is an energy distribution having a strong Gaussian distribution at the center, and the metal precursor coating 4 is heated by the first laser beam and the metal precursor by the second laser beam. Since the coating 4 is metallized, adjustment and control of the laser beam irradiation energy can be achieved by setting the center of the laser beam irradiation region having the highest irradiation energy density in the laser beam irradiation region to substantially the same position. It becomes easy.

  The center of the irradiation region of the second laser beam is set at a position closer to the back in the scanning direction than the center of the irradiation region of the first laser beam, so that the heat treatment time of the metal precursor coating 4 is lengthened. It is possible to easily adjust the irradiation energy of the first laser beam.

  Furthermore, in this Embodiment 2, although the glass substrate was used for the board | substrate 1, it is not restricted to this, The ceramic board | substrate generally used for a wiring board, a glass epoxy board, a flexible polyimide board, etc. It may be used.

  In addition, as shown in the second embodiment, the heating time is not shortened, but the heating time can be left as it is, and the laser output can be weakened. This is because the metal wiring on the substrate having poor heat resistance is used. It is effective for forming a substrate.

  As described above, in the second embodiment, the metal precursor film 4 is formed from the metal fine particle dispersion liquid 2 on the substrate, and the laser beam or the like is formed under the condition that the metal precursor film 4 is not fused between the metal fine particles. By scanning and irradiating the first energy beam and performing the heat treatment, the second energy beam such as a laser beam is scanned and irradiated to form the metal film 14 without using an expensive apparatus such as photolithography. A metal wiring can be formed. Further, an arbitrary wiring pattern can be formed on the metal wiring having a fine wiring width based on the output of the laser beam from the control device without using a mold such as a photomask. Furthermore, the formation time of the wiring pattern can be shortened, and the productivity of the metal wiring board 16 can be improved.

  In addition, a wiring pattern having high adhesion to the substrate is formed without mixing a photothermal conversion material into the metal fine particle dispersion liquid 2 or providing a photothermal conversion layer between the substrate 1 and the metal precursor coating 4. Therefore, the processing steps can be simplified as compared with the conventional metal wiring manufacturing method. Further, as compared with the case of the first embodiment, since only the portion where the wiring is formed can be heated, the metal precursor film 4 where the wiring is not formed can be easily removed. In addition, since the heat treatment of the metal precursor film 4 and the energy beam scanning irradiation process can be performed almost simultaneously, the manufacturing process of the metal wiring board can be simplified as compared with the first embodiment. .

(Embodiment 3)
In the first and second embodiments, the metal precursor film formed on the substrate is processed by heat or heat treatment using laser light. In the third embodiment, the metal precursor film is processed by ultraviolet irradiation. The case will be described.

  The metal wiring board manufacturing method according to the third embodiment is the same as the other processes except that the heat treatment process of S12 in FIG. 1 of the first embodiment is changed to an ultraviolet irradiation process. This ultraviolet irradiation treatment step is a step of performing ultraviolet irradiation treatment on the metal precursor film formed on the substrate surface. By this ultraviolet irradiation, the metal fine particles in the metal precursor coating 4 are brought into a state immediately before being fused.

  Next, details of the method of manufacturing the metal wiring board according to the third embodiment will be described. First, the metal fine particle dispersion liquid 2 whose metal is silver was used. Similar to the first embodiment, the fine metal particle dispersion liquid 2 is applied to the cleaned glass substrate 1 by spin coating. Specifically, as shown in FIG. 2 of the first embodiment, after the metal fine particle dispersion liquid 2 is dropped on the entire surface of the glass substrate 1 using the pipette 3 on the surface of the glass substrate 1 set in the spin coater, By holding the substrate 1 at a predetermined rotation speed for a predetermined time, for example, at a rotation speed of 1000 rotations / minute for 30 seconds, a film made of the metal fine particle dispersion liquid 2 was formed on the surface of the glass substrate 1. When spin coating is performed after the metal fine particle dispersion liquid 2 is applied to the glass substrate 1, the excess metal fine particle dispersion liquid 2 is scattered and a part of the solvent of the metal fine particle dispersion liquid 2 remaining on the surface of the glass substrate 1 is evaporated. A metal precursor film 4 made of a reddish brown film is formed on the surface of the glass substrate 1.

  Next, an ultraviolet irradiation treatment is performed on the metal precursor film 4 formed on the surface of the glass substrate 1. FIG. 10 is a diagram showing a schematic configuration of an ultraviolet irradiation apparatus according to Embodiment 3 of the present invention. In FIG. 5, reference numeral 25 denotes an ultraviolet lamp. The ultraviolet ray emitted from the ultraviolet lamp 25 is irradiated on the entire surface of the glass substrate 1 on which the metal precursor film 4 is formed, and an ultraviolet irradiation process is performed.

  Next, the surface of the metal precursor coating 4 that has been subjected to the ultraviolet irradiation treatment is scanned with energy rays. Here, the laser beam irradiation scanning device 6 used in FIG. 6 of the first embodiment is used as the energy beam irradiation scanning device.

  As in the first embodiment, the metal precursor film 4 is scanned and irradiated with a laser beam, so that the metal precursor film 4 becomes the metal film 14 and a metal pattern is formed. However, the unirradiated region 15 of the laser beam is the metal precursor film 4 and is an aggregate of metal fine particles, and therefore is an unstable substance, and is desirably removed for use as the metal wiring board 16. . The removal of the metal precursor film 4 in the unirradiated region 15 of the laser beam can be performed by immersing the glass substrate 1 in the solvent used in the metal fine particle dispersion liquid 2. This is because the metal precursor film 4 remaining on the glass substrate 1 swells by being immersed in the solvent used in the metal fine particle dispersion liquid 2 and can be easily removed. If it is difficult to remove, an ultrasonic cleaner or the like may be used. Finally, the metal wiring board 16 is formed on the glass substrate by rinsing with the same solvent as that used for the metal fine particle dispersion liquid 2.

  As described above, the metal fine particle-dispersed liquid 2 is applied to the substrate 1 to form the metal wiring substrate 16. In order to investigate the effect of the ultraviolet irradiation treatment after the formation of the metal precursor film 4 of the third embodiment. 5 shows the result of examining the electrical resistance of the wiring pattern 17 by preparing the following test sample. Note that the wiring pattern 17 of the test sample uses the same wiring pattern 17 as that in FIG. 8 of the first embodiment, and the laser beam irradiation scanning speed is changed for the linear portion 18 of the wiring pattern 17 in the same manner as in the first embodiment. Formed while.

As the substrate 1, a polyimide resin substrate was used, and a metal fine particle dispersion liquid 2 made of silver was used. The metal fine particle-dispersed liquid 2 is applied onto the polyimide resin substrate by spin coating, and the metal precursor film 4 is formed on the polyimide resin substrate, followed by ultraviolet irradiation treatment. The ultraviolet irradiation treatment was performed by irradiating the metal precursor film 4 with ultraviolet rays having a wavelength of 405 nm and an output of 50 mW / cm ² for 10 minutes to obtain a test body of Embodiment 3. A plurality of test bodies of Embodiment 3 subjected to such heat treatment were formed.

  Further, as a control sample for the experiment, a metal precursor film 4 was formed on a polyimide resin substrate as in the third embodiment. Thereafter, a plurality of substrates on which the metal precursor coating 4 was not subjected to ultraviolet irradiation treatment were formed as test bodies of Comparative Example 3.

  Next, the scanning speed of the laser beam irradiation (moving speed of the substrate holder in the x direction) is applied to the substrate of the test body of Embodiment 3 and the substrate of the test body of Comparative Example 3 using the laser beam irradiation scanning device 6 described above. The metal precursor film 4 was converted to the metal film 14 by irradiation with a laser beam. Finally, the laser beam unirradiated region 15 of the metal precursor coating 4 is immersed and removed in toluene, which is the solvent of the metal fine particle dispersion liquid 2, and rinsed to obtain the test sample of Embodiment 3 and the test sample of Comparative Example 3. Produced. And the electrical resistance between each terminal part 19 of the test body of these Embodiment 3 and the comparative example 3 was measured. (Table 3) is a table | surface which shows the measurement result of the electrical resistance about the test body by Embodiment 3 and a comparative example.

  As shown in (Table 3), in the test body of the third embodiment, even when the laser beam irradiation scanning speed is increased, the electric resistance of the linear portion is almost 8.7Ω. On the other hand, in the test body of Comparative Example 3, when the laser beam irradiation scanning speed was increased, the electrical resistance of the linear portion showed a tendency to increase, and eventually the electrical resistance increased rapidly.

  This is because even if the scanning speed of the specimen is increased, the electrical resistance is stable in the specimen of Embodiment 3, and conversion from the metal precursor film 4 to the metal film 14 by irradiation with a laser beam, that is, a metal precursor. This shows that the fusion of the metal fine particles forming the coating 4 occurs regardless of the scanning speed of the specimen. On the other hand, in the test body of Comparative Example 3, when the laser beam irradiation scanning speed is increased, the metal precursor film 4 is converted into the metal film 14 by the laser beam irradiation, that is, the metal fine particles forming the metal precursor film 4 are mutually bonded. This is considered to be an incomplete fusion, which appears as a tendency to increase the electrical resistance of the straight portion 18.

  Actually, when the surface of the test specimen is observed, a smooth metal film 14 is formed regardless of the scanning speed in the specimen of the third embodiment, but the scanning speed increases in the specimen of Comparative Example 3. It was confirmed that the smoothness was lost. As described above, in the third embodiment in which the ultraviolet ray irradiation treatment is performed before the metal precursor coating 4 is irradiated with the laser beam, the comparative example 3 in which no treatment is performed before the metal precursor coating 4 is irradiated with the laser beam. As compared with, the smooth metal coating 14 can be formed even if the irradiation scanning speed of the laser beam is increased. This is because, when the metal precursor film 4 is converted into the metal film 14 by heating, the metal precursor film 4 is preliminarily irradiated with ultraviolet rays, thereby converting, that is, between the metal fine particles constituting the metal precursor film 4. It is thought that the fusion due to the heat is likely to occur.

In the third embodiment, the ultraviolet irradiation treatment of the metal precursor film 4 was performed under the condition of irradiating with a wavelength of 405 nm and 50 mW / cm ² for 10 minutes. It varies depending on the type of metal of the metal fine particles constituting the metal precursor coating 4, the diameter of the metal fine particles, the dispersant covering the periphery of the individual metal fine particles, etc., and the optimum conditions may be determined in consideration of these. .

  In the third embodiment, a polyimide resin substrate is used as the substrate 1. However, the present invention is not limited to this, and a ceramic substrate or a glass epoxy substrate generally used for a wiring substrate may be used. .

  Furthermore, although the thickness of the wiring is reduced to about 0.5 μm in the third embodiment, the thickness of the wiring portion can be increased by further applying a plating film or the like to the wiring.

  As described above, in the third embodiment, the metal precursor film 4 is formed from the metal fine particle dispersion liquid 2 on the substrate, and the metal precursor film 4 is irradiated with ultraviolet rays and then irradiated with an energy beam such as a laser beam. By forming the metal coating 14, the metal wiring can be formed without using an expensive apparatus such as photolithography. Further, an arbitrary wiring pattern can be formed on the metal wiring having a fine wiring width based on the output of the laser beam from the control device without using a mold such as a photomask. Furthermore, the formation time of the wiring pattern can be shortened, and the productivity of the metal wiring board 16 can be improved.

  In addition, a wiring pattern having high adhesion to the substrate is formed without mixing a photothermal conversion material into the metal fine particle dispersion liquid 2 or providing a photothermal conversion layer between the substrate 1 and the metal precursor coating 4. Therefore, the processing steps can be simplified as compared with the conventional metal wiring manufacturing method. Further, as compared with the first and second embodiments, it is not necessary to place the substrate on which the metal precursor film 4 is formed in a high temperature environment. There is also an effect that a wiring having high adhesion and uniform electric resistance can be easily formed.

  In the first and third embodiments, a laser beam is used as the energy beam, and in the second embodiment, the laser beam is used as the second energy beam. However, the energy beam is not limited to the laser beam, and the metal precursor coating 4 is heated. Any energy that can be converted into the metal coating 14 can be applied to the metal precursor coating 4. For example, an electron beam or an infrared light source may be used as the energy beam. However, when a wiring pattern consisting of fine lines is required, it is often desirable that the energy beam irradiation area is narrow, and from this standpoint, a laser light source that can easily focus the light beam by the optical system 13 is used. It is excellent in that it is easy. In addition, the laser beam is easy to select because it has a wide selection range such as a semiconductor laser and a gas laser and there are many types of wavelengths of the laser beam. The wavelength of the laser beam can be efficiently converted into heat on the metal precursor coating 4 by selecting the wavelength at which the metal precursor coating 4 has a large absorption, and the metal precursor coating 4 It is effective for converting 4 into the metal coating 14.

  In the first to third embodiments, the metal fine particle dispersion liquid 2 made of silver having an average particle size of 5 nm is used. However, the average particle size of the metal particles is not limited to the average particle size of 5 nm. It may be larger than 5 nm or conversely smaller than 5 nm.

  However, when the average particle size of the metal fine particles is increased to, for example, 20 nm or more, the dispersion state of the metal fine particles is deteriorated, and sedimentation of the metal fine particles to the lower portion of the metal fine particle dispersion liquid 2 occurs. As a result, the energy required for the conversion from the metal precursor film 4 to the metal film 14, that is, the fusion temperature due to the heat between the metal fine particles is increased, and a high temperature is required for forming the metal film. Problems occur. Conversely, when the average particle size of the metal fine particles is reduced, the activity of the metal fine particles is increased, and fusion aggregation of the metal fine particles proceeds during storage of the metal fine particle dispersion liquid 2. 2 uniformity deteriorates. As a result, the metal precursor film 4 becomes non-uniform and eventually the non-uniformity also occurs in the metal film 14, thereby causing problems such as affecting the non-uniformity of the wiring of the metal wiring board 16. Cause. As described above, the average particle diameter of the metal fine particles may be determined based on the reactivity of the selected metal, the temperature at which the metal fine particles start to fuse, and the like.

  As described above, the method for manufacturing a metal wiring board according to the present invention is useful when metal fine particles are dispersed in an organic solvent, applied onto the board, and patterned into a desired shape.

Process drawing which shows the manufacturing process of the metal wiring board of Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows an example of the process sequence of the metal wiring board formation method by Embodiment 1 of this invention The figure which shows the wiring pattern of the test sample by Embodiment 1 of this invention The figure which shows schematic structure of the irradiation scanning apparatus of the laser beam by Embodiment 2 of this invention The figure which shows schematic structure of the ultraviolet irradiation device by Embodiment 3 of this invention

Explanation of symbols

1 Substrate (glass substrate)
2 Metal fine particle dispersion liquid 3 Pipette 4 Metal precursor coating 5 Hot plate 6 Irradiation scanning device 7 Substrate holder 8 Laser light source 9 Laser light emitting unit 10 Control unit 11 Substrate holder 12 Drive system 13, 24 Optical system 14 Metal coating 15 Not yet Irradiation area 16 Metal wiring board 17 Wiring pattern 18 Linear portion 19 Terminal portion 20 First laser light emitting portion 21 Second laser light emitting portion 22 First laser light source 23 Second laser light source 25 Ultraviolet lamp

Claims (13)

A metal fine particle dispersion liquid obtained by dispersing metal fine particles in a solvent is applied to the substrate surface to form a metal precursor film on the substrate surface, and the metal precursor film is subjected to a heat treatment, and the surface of the metal precursor film A metal wiring board, wherein the metal precursor coating in the energy beam irradiation region is metallized, and the metal precursor coating in the non-irradiation region of the energy beam is removed. Production method. The method of manufacturing a metal wiring board according to claim 1, wherein the energy beam is a laser beam. A metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent is applied to the surface of the substrate to form a metal precursor film on the surface of the substrate, and the first energy line and the second energy are formed on the surface of the metal precursor film. Scanning irradiation with a line, heat treatment of the metal precursor film in the irradiation region of the first energy beam, and the irradiation region of the second energy beam in the irradiation region of the first energy beam A method for producing a metal wiring board, comprising metallizing a metal precursor film and removing the metal precursor film in an unirradiated region of the second energy beam. 4. The method of manufacturing a metal wiring board according to claim 3, wherein an energy density of the first energy line is smaller than an energy density of the second energy line. 5. The method of manufacturing a metal wiring board according to claim 3, wherein an irradiation region of the first energy beam is wider than an irradiation region of the second energy beam. 5. The method of manufacturing a metal wiring board according to claim 3, wherein the irradiation region of the second energy beam is included in the irradiation region of the first energy beam. The center in the direction perpendicular to the scanning direction of the irradiation region of the first energy beam and the center in the direction perpendicular to the scanning direction of the irradiation region of the second energy beam are substantially at the same position. The manufacturing method of the metal wiring board as described in any one of Claims 3-6. The center of the irradiation region of the second energy beam is at a position closer to the back in the scanning direction than the center of the irradiation region of the first energy beam. The manufacturing method of the metal wiring board of description. The method of manufacturing a metal wiring board according to any one of claims 3 to 8, wherein the first energy line and the second energy line are laser beams. A metal fine particle dispersion liquid in which metal fine particles are dispersed in a solvent is applied to the substrate surface to form a metal precursor film on the substrate surface, and the metal precursor film is subjected to ultraviolet irradiation treatment, A metal wiring board comprising: scanning and irradiating an energy beam on a surface to metallize the metal precursor coating in an irradiation region of the energy beam; and removing the metal precursor coating in an unirradiated region of the energy beam. Manufacturing method. The method of manufacturing a metal wiring board according to claim 10, wherein the energy beam is a laser beam. The method for producing a metal wiring board according to claim 1, wherein the metal fine particles have an average particle diameter of 20 nm or less. The metal wiring board manufactured by the manufacturing method of the metal wiring board as described in any one of Claims 1-12.

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