TWI724283B - Film forming device and film forming method - Google Patents

Abstract

The present invention provides a film forming device that can quickly cure ink without using photocurable ink. The substrate is held on the workbench. The inkjet head ejects thermosetting ink toward the substrate held on the worktable. The non-contact heating member heats the substrate held on the workbench in a non-contact manner.

Description

Film forming device and film forming method

The invention relates to a film forming device and a film forming method.

There is known a device that discharges photocurable (ultraviolet curable) ink from an inkjet head and the like and draws it on a recording medium such as a substrate (Patent Document 1). After the ultraviolet curable ink is placed on the recording medium, the ink can be quickly cured by irradiating an appropriate amount of ultraviolet light. (Prior Art Document) (Patent Document) 　　Patent Document 1: Japanese Patent Application Laid-Open No. 2008-188983

(Problems to be solved by the present invention) 　　Ultraviolet curable inks used for solder mask applications of printed circuit boards have higher viscosity than normal inks. Therefore, it is better to reduce the viscosity by heating the ink supplied to the inkjet head to the extent that the ink can be discharged from the inkjet head. If the temperature of the ink becomes too high, the deterioration of the ink accelerates. If the temperature of the ink is too low, the viscosity of the ink becomes higher than the target viscosity, so the discharge of the ink becomes unstable, and ink clogging or the like is likely to occur. "The object of the present invention is to provide a film forming apparatus and a film forming method capable of rapidly curing ink without using photocurable ink. (Means for Solving the Problem) 　　 According to an aspect of the present invention, a film forming apparatus is provided, which has: a worktable for holding a substrate; an inkjet head for ejecting thermosetting ink toward the substrate held on the worktable; And the non-contact heating member heats the substrate held on the table in a non-contact manner. According to another aspect of the present invention, a film forming method is provided, which has: a process of heating a local area of a substrate in a non-contact manner; and forming the heated area of the substrate by adhering and curing thermosetting ink The manufacturing process of the film. (Effects of the Invention) "The thermosetting ink is attached to the area where the substrate is heated in a non-contact manner, thereby curing the thermosetting ink.

1A to 1C, the film forming apparatus based on the embodiment will be described. Fig. 1A is a schematic side view of the film forming apparatus based on this embodiment. The table 10 holds the substrate 30 thereon. The table 10 has, for example, a vacuum chuck mechanism, and sucks and fixes the substrate 30. The inkjet head 15 discharges thermosetting ink toward the substrate 30 held on the table 10. The laser light source 16 as a non-contact heating member irradiates the substrate 30 held on the table 10 with a laser beam, thereby heating a local area of the substrate 30 in a non-contact manner. The moving mechanism 13 moves one of the substrate 30 and the inkjet head 15 held on the table 10 relative to the other. The moving direction is parallel to the upper surface of the table 10. The moving mechanism 13 includes a guide 11 that guides the workbench 10 in one direction and a driving part 12 that moves the workbench 10 along the guide 11. The control device 20 controls the discharge of ink from the inkjet head 15. Furthermore, the control device 20 moves the table 10 at a target speed by controlling the drive unit 12. The control device 20 stores pattern data defining the planar shape of the film to be formed. The control device 20 controls the inkjet head 15 and the moving mechanism 13 based on the pattern data, thereby causing the thermosetting ink to adhere to a desired location on the upper surface of the substrate 30, and the resin film 32 can be formed. FIG. 1B is a perspective view of the laser light source 16. The laser light source 16 outputs a laser beam 18 with a long beam profile 18A. As the laser light source 16, a laser diode (LD) strip with a water cooling mechanism can be used. For example, by arranging 5 LD bars with an array width of 10 mm, LD bars with an array width of 50 mm are obtained. The oscillation wavelength of the laser light source 16 is, for example, 808 nm, and the beam cross-section has a strip shape with a size of about 50 mm in the long axis. The moving direction of the substrate 30 when the film is formed is orthogonal to the long axis of the beam section. The divergence angle of the short axis is about 1° with the lens, and the beam size of the short axis on the substrate separated by 50mm is about 1.5mm. The output of the laser light source 16 is set to a size that can raise the temperature of the substrate 30 to the target temperature. FIG. 1C is a plan view showing the relative relationship among the inkjet head 15, the beam profile 18A of the laser beam, and the moving direction 58 of the substrate 30. The nozzle row 15A composed of a plurality of nozzle holes of the inkjet head 15 is orthogonal to the movement direction 58 of the substrate 30. In a plan view, the long beam cross section 18A is arranged in parallel with the nozzle row 15A. The beam profile 18A is longer than the nozzle row 15A. Therefore, the entire area where the thermosetting ink discharged from the inkjet head 15 adheres can be heated by irradiating the laser. Next, the operation of the film forming apparatus according to this embodiment will be described. The control device 20 operates the moving mechanism 13 to pass under the inkjet head 15 after the partial area of the substrate 30 is heated by the laser light source 16. Thereby, a local area of the substrate 30 is heated by the laser light source 16 in a non-contact manner, and then, the ink discharged from the inkjet head 15 adheres to the heated area. The power density of the laser beam, the size of the beam profile, and the moving speed of the substrate 30 are set so that the surface temperature of the substrate 30 when the ink adheres to the substrate 30 maintains the curing temperature of the ink or more. Therefore, the ink discharged from the inkjet head 15 hardens as soon as it adheres to the substrate 30. The substrate 30 is moved relative to the laser light source 16 and the inkjet head 15, whereby the heating area and the area where the thermosetting ink adheres are moved within the surface of the substrate 30. Thereby, the resin film 32 in which the thermosetting ink is cured can be formed on the surface of the substrate 30. Next, the excellent effects of the above-mentioned embodiment will be described. In the above-mentioned embodiment, thermosetting ink is used to form a film. Generally, compared with ultraviolet curable inks, thermosetting inks have excellent adhesion to various raw materials and chemical resistance, and have low viscosity. For example, it is possible to obtain a low-viscosity thermosetting ink capable of stably ejecting ink from the inkjet head 15 at room temperature. Therefore, there is no need to prepare an ink heating device for reducing the viscosity of the ink. Furthermore, the laser light source 16 is used to locally heat the substrate 30 in the above-mentioned embodiment. For example, the table 10 (FIG. 1A) can be provided with a hot plate function to substantially uniformly heat the entire substrate 30. However, in this method, it is necessary to wait a long time after the substrate 30 is held on the table 10 and then heated to the target temperature. In this embodiment, the waiting time for heating is not required, so it is possible to avoid the decrease in flux caused by the heating treatment. In addition, if the table 10 itself is heated, it is difficult to maintain the mechanical accuracy of the table 10 and the moving mechanism 13 due to the influence of thermal expansion. In this embodiment, there is no need to heat the table 10 and the substrate 30 is heated in a non-contact manner, so it is possible to avoid a decrease in mechanical accuracy. Immediately after the ink is attached to the substrate 30, if the laser beam is injected into the ink attachment site to heat the substrate, it is confirmed that the ink is scattered due to the high energy of the laser beam. In this embodiment, the substrate 30 is heated before the ink adheres, so that the ink does not scatter. In addition, since the ink adheres to the substrate 30 and immediately starts curing, it is possible to prevent excessive diffusion or bleeding of the ink. Next, a description will be given of a modification of the above-mentioned embodiment. In the above-mentioned embodiment, the laser light source 16 (FIG. 1B) is used as the non-contact heating member, but in addition, a heating device capable of locally heating the substrate 30 in a non-contact manner may be used. For example, it is also possible to use a device for heating by light energy such as a light emitting diode (LED), or a high-frequency induction heating device. In the above embodiment, the substrate 30 is moved relative to the laser light source 16 and the inkjet head 15. Contrary to this, the laser light source 16 and the inkjet head 15 can also be moved relative to the substrate 30. In addition, in the above-mentioned embodiment, the laser beam output from the laser light source 16 is a continuous wave laser beam, but it can also be a pulse laser beam. In the above-mentioned embodiment, the nozzle row 15A (FIG. 1C) is orthogonal to the movement direction 58 (FIG. 1C) of the substrate 30, but it does not need to be orthogonal. What is necessary is just to make the nozzle row 15A cross|intersect the movement direction 58 of the board|substrate 30. Next, with reference to FIGS. 2A to 2C, the simulation results of the temperature change when the laser beam is incident on the substrate with copper foil will be described. FIG. 2A is a cross-sectional view of the substrate 50 as the simulation target. The substrate 50 has a three-layer structure composed of an epoxy substrate 51 with a thickness of 800 μm, a copper foil 52 with a thickness of 30 μm, and an epoxy layer 53 with a thickness of 10 μm. In the embodiment shown in FIGS. 1A to 1C, when the laser beam is irradiated, the resin film 32 is not formed on the substrate 30 (FIG. 1A), but the ink attached to the substrate 30 needs to be heated to the curing temperature. In the simulation, the epoxy layer 53 corresponding to the ink attached to the substrate 30 is included in the heating object. FIG. 2B is a diagram showing the positional relationship between the beam spot 56 on the surface of the substrate 50 and the specific location 55 on the substrate 50. The diameter of the beam spot 56 is set to 0.5 mm, the power density of the laser beam on the surface of the substrate 50 is set to 12 kW/cm ² , and the moving speed of the substrate 50 is set to 200 mm/s. The specific part 55 on the substrate 50 moves at a moving speed of 200 mm/s and passes through the center of the beam spot 56. At this time, the time for the laser beam to irradiate the specific part 55 becomes 2.5 ms. In the simulation, it is assumed that the total energy of the laser beam is absorbed. FIG. 2C is a graph showing the simulation result of the temperature change of the surface of the copper foil 52 at the specific location 55. The horizontal axis represents the elapsed time in the unit "ms", and the vertical axis represents the temperature in the unit "°C". If the laser beam starts to strike a specific part 55, the temperature rises, and the maximum temperature exceeds 250°C. The time above 150°C is about 5ms. When the laser beam irradiation ends, the temperature drops sharply to about 120°C, but the temperature drops slowly thereafter. It is considered that the temperature at the time when the temperature decrease becomes slow varies depending on the power density of the laser beam or the irradiation time (the size of the beam spot 56). It is considered that if the temperature at the time when the temperature decrease becomes slower than the curing temperature of the ink, the thermosetting ink can be cured. From the simulation results shown in FIGS. 2A to 2C, it is believed that the thermosetting ink can be cured by adjusting the power density of the laser beam and the size of the beam spot 56. Next, the results of a simple preliminary experiment to confirm that the thermosetting ink can be cured will be described. After irradiating the copper foil with a laser beam under the conditions of a wavelength of 808nm, a beam spot diameter of 0.5mm, and a substrate moving speed of 200mm/s, the heated copper foil was sprayed with thermosetting ink. As a result, it was possible to confirm the curing of the thermosetting ink in the area where the laser was irradiated. Next, referring to FIG. 3, the preferred wavelength of the laser beam used for heating will be described. Fig. 3 is a graph showing the wavelength dependence of the reflectance of gold, silver, and copper after electrolytic polishing. The horizontal axis represents the wavelength in the unit "nm", and the vertical axis represents the reflectance. In order to effectively heat the metal foil on the substrate, it is preferable to use a laser beam of a wavelength region with a low reflectivity. It can be seen from FIG. 3 that, for example, in the case where a copper foil is provided on the surface of the substrate, it is preferable to use a laser beam having a wavelength range of 570 nm or less. It can be seen that when the gold foil is provided on the surface of the substrate, it is better to use a laser beam in the wavelength range of 520 nm or less. It can be seen that when the silver foil is provided on the surface of the substrate, it is better to use a laser beam in the wavelength range of 350 nm or less. Next, referring to FIGS. 4A and 4B, a film forming apparatus based on another embodiment will be described. Hereinafter, a description of the structure common to the embodiment shown in FIGS. 1A to 1C will be omitted. Fig. 4A is a schematic side view of the film forming apparatus based on this embodiment. In the embodiment shown in FIG. 1A, the laser light source 16 is only arranged on one side of the inkjet head 15. However, in this embodiment, laser light sources 16, 17 are arranged on both sides of the inkjet head 15 respectively. 4B is a plan view showing the relative relationship between the inkjet head 15 based on the film forming apparatus of the present embodiment, the beam profiles 18A, 19A based on the laser light sources 16, 17 and the direction in which the substrate 30 moves 58A, 58B. The beam cross sections 18A and 19A are respectively arranged on both sides of the nozzle row 15A. When the substrate 30 is moved in the direction 58A from the beam section 18A to the nozzle row 15A, the laser light source 16 for the beam section 18A is operated, and the other laser light source 17 is not operated. Conversely, when the substrate 30 is moved in the direction 58B from the beam section 19A to the nozzle row 15A, the laser light source 17 for the beam section 19A is operated, and the other laser light source 16 is not operated. As described above, in this embodiment, even when the substrate 30 is moved in any of two directions opposite to each other, the ink can be discharged from the inkjet head 15 to form a film. Next, referring to FIG. 5, a film forming apparatus based on another embodiment will be described. Hereinafter, a description of the structure common to the embodiment shown in FIGS. 1A to 1C will be omitted. FIG. 5 is a graph showing the light intensity distribution related to the long axis of the beam profile 18A. The light intensity is approximately constant in regions other than the vicinity of both ends of the long axis. At both ends of the beam profile, the light intensity is higher than other areas. By setting these light intensity distributions to compensate for the insufficient temperature rise near the two ends of the beam profile 18A, it is possible to heat to a sufficient temperature near the two ends. The above-mentioned embodiments are exemplified, and it is of course possible to make partial substitutions or combinations of the structures shown in different embodiments. Regarding the same action and effect based on the same structure of a plurality of embodiments, each embodiment will not be described one by one. Furthermore, the present invention is not limited to the above-mentioned embodiment. For example, for those skilled in the art, it is obvious that various changes, improvements, and combinations can be made.

10‧‧‧Working table 11‧‧‧Guide 12‧‧‧Drive unit 13‧‧‧Moving mechanism 15‧‧‧Inkjet head 15A‧‧‧Nozzle row 16,17‧‧‧Laser light source 18‧‧‧ Laser beam 18A, 19A‧‧‧Beam profile 20‧‧‧Control device 30‧‧‧Substrate 32‧‧‧Resin film 50‧‧‧Substrate 51‧‧‧Epoxy substrate 52‧‧‧Copper foil 53‧‧‧Epoxy layer 55‧‧‧Specific parts on the substrate 56‧‧‧Beam spots 58, 58A, 58B‧‧‧Substrate movement direction

In Fig. 1, Fig. 1A is a schematic side view of the film forming apparatus based on the embodiment, Fig. 1B is a perspective view of a laser light source, and Fig. 1C is a diagram showing the inkjet head, the beam profile of the laser beam, and the moving direction of the substrate The top view of the relative relationship. In Figure 2, Figure 2A is a cross-sectional view of the substrate as the simulation target, Figure 2B is a diagram showing the positional relationship between the beam spot on the substrate surface and a specific part on the substrate, and Figure 2C is a simulation of the temperature change of the specific part Graph of results.　　 Figure 3 is a graph showing the wavelength dependence of the reflectance of electropolished gold, silver, and copper. In FIG. 4, FIG. 4A is a schematic side view of a film forming apparatus based on other embodiments, and FIG. 4B is an inkjet head based on the film forming apparatus of this embodiment, the beam profile based on the laser light source, and the direction of movement of the substrate The top view of the relative relationship between.　　 FIG. 5 is a graph showing the light intensity distribution related to the long axis of the beam profile of the film forming apparatus according to still another embodiment.

10‧‧‧Working table

11‧‧‧Guide

12‧‧‧Drive

13‧‧‧Mobile Organization

15‧‧‧Inkjet head

15A‧‧‧Nozzle row

16‧‧‧Laser light source

18‧‧‧Laser beam

18A‧‧‧Beam Profile

20‧‧‧Control device

30‧‧‧Substrate

32‧‧‧Resin film

58‧‧‧Substrate movement direction

Claims (8)

A film forming device has: a worktable for holding a substrate; an inkjet head for discharging thermosetting ink toward the substrate held on the worktable; and a non-contact heating member that is heated and held on the substrate in a non-contact manner The substrate before the thermosetting ink is ejected on the worktable, the non-contact heating member forms a long beam profile, and the light intensity distribution in the long axis of the beam profile is light in areas other than the vicinity of both ends. The intensity is approximately constant, and the light intensity near the aforementioned ends is higher than in other regions. The film forming apparatus described in the first item of the scope of patent application further has: a moving mechanism that moves one of the substrate and the inkjet head held on the worktable relative to the other; and a control device that controls The inkjet head and the moving mechanism, the non-contact heating member heats a local area of the substrate held on the table, and the control device controls the moving mechanism and the inkjet head so that the non-contact heating member The heated area adheres to the thermosetting ink discharged from the inkjet head. The film forming apparatus described in the first item of the scope of patent application, wherein the non-contact heating member heats the substrate by injecting a laser beam onto a local area of the substrate held on the table. According to the film forming apparatus described in the second or third scope of the patent application, the inkjet head includes a nozzle row composed of a plurality of nozzles, and the plurality of nozzles are arranged in a direction intersecting the moving direction of the substrate, by The region heated by the non-contact heating member has an elongated shape parallel to the nozzle row and longer than the nozzle row. As for the film forming apparatus described in claim 3, the inkjet head includes a nozzle row composed of a plurality of nozzles, and the plurality of nozzles are arranged in a direction intersecting with the moving direction of the substrate, and the above-mentioned non- The area contacting the heating member and entering the laser beam has an elongated shape parallel to the nozzle row, and has a light intensity distribution where the light intensity at both ends of the elongated shape is higher than the light intensity in other areas. A film forming method comprising: a process of forming a long beam profile by a non-contact heating member; and a process of heating a local area of a substrate by the beam profile in a non-contact manner; and after the substrate is heated In the area, the process of forming a film by attaching and curing thermosetting ink; The light intensity distribution in the long axis of the beam profile is that the light intensity in the regions other than the vicinity of both ends is substantially constant, and the light intensity in the vicinity of the both ends is higher than the other regions. The film forming method described in the scope of the patent application described in item 6, wherein in the heating process, a laser beam is incident on the substrate to heat a local area of the substrate. The film forming method described in claim 6 or 7, wherein the heating area and the area where the thermosetting ink adheres are moved within the surface of the substrate while forming the film.

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