TW201902583A - Film forming device and film forming method - Google Patents

Abstract

According to the present invention, a substrate is held on a table. An inkjet head ejects thermosetting ink onto the substrate held on the table. A non-contact heating means heats, in a non-contacting manner, the substrate held on the table. Consequently, ink can be quickly cured without using a photocurable ink.

Description

Film forming device and film forming method

The present invention relates to a film forming apparatus and a film forming method.

A device is known in which a photocurable (ultraviolet curable) ink is ejected from an inkjet head or the like and drawn on a recording medium such as a substrate (Patent Document 1). After the ultraviolet curable ink is arranged on the recording medium, the ink can be rapidly cured by irradiating an appropriate amount of ultraviolet rays. (Prior Art Document) (Patent Document) Patent Document 1: Japanese Patent Application Laid-Open No. 2008-188983

(Problems to be Solved by the Present Invention) (1) Ultraviolet curable inks used for solder mask applications of printed boards and the like have higher viscosity than ordinary inks. Therefore, it is preferable to reduce the viscosity by heating the ink supplied to the inkjet head until the ink can be ejected from the inkjet head. If the temperature of the ink becomes too high, the deterioration of the ink will be accelerated. If the temperature of the ink is too low, the viscosity of the ink becomes higher than the target viscosity, and therefore the discharge of the ink becomes unstable, and ink clogging and the like are liable to occur. An object of the present invention is to provide a film forming apparatus and a film forming method capable of rapidly curing ink without using a photocurable ink. (Means to solve the problem) According to an aspect of the present invention, a film forming apparatus is provided, which includes: a table that holds a substrate; and an inkjet head that discharges a thermosetting ink toward the substrate that is held on the table; The non-contact heating member heats the substrate held on the work table in a non-contact manner. According to another aspect of the present invention, there is provided a film forming method comprising: a process of heating a local area of a substrate in a non-contact manner; and forming a heated area of the substrate by attaching and curing a thermosetting ink Film process. (Effects of the Invention) (1) The thermosetting ink can be cured by attaching the thermosetting ink to a region where the substrate is heated in a non-contact manner.

A film forming apparatus according to an embodiment will be described with reference to FIGS. 1A to 1C. FIG. 1A is a schematic side view of a film forming apparatus according to this embodiment. The stage 10 holds the substrate 30 thereon. The table 10 has, for example, a vacuum chuck mechanism, and the substrate 30 is sucked and fixed. The inkjet head 15 ejects thermosetting ink toward the substrate 30 held on the table 10. The laser light source 16 as a non-contact heating member irradiates a laser beam to the substrate 30 held on the table 10, 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 for unidirectionally guiding the table 10 and a driving part 12 for moving the table 10 along the guide 11. The control device 20 controls the discharge of ink from the inkjet head 15. Furthermore, the control device 20 controls the drive unit 12 to move the table 10 at a target speed. 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 allowing the thermosetting ink to adhere to a desired portion on the upper surface of the substrate 30 to form the resin film 32. FIG. 1B is a perspective view of the laser light source 16. The laser light source 16 outputs a laser beam 18 whose beam profile 18A is a long shape. 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 having an array width of 10 mm, an LD bar having an array width of 50 mm is obtained. The laser light source 16 has an oscillation wavelength of, for example, 808 nm, and the beam cross section has a long shape with a length in the longitudinal direction of about 50 mm. The movement direction of the substrate 30 when forming the film is orthogonal to the long axis of the beam cross section. The divergence angle band lens in the short axis direction is about 1 °, and the beam size in the short axis direction on the substrate 50 mm apart is about 1.5 mm. The output of the laser light source 16 is set to a magnitude capable of increasing the temperature of the substrate 30 to a target temperature. FIG. 1C is a plan view showing the relative relationship between the inkjet head 15, the beam cross section 18A of the laser beam, and the moving direction 58 of the substrate 30. A nozzle row 15A composed of a plurality of nozzle holes of the inkjet head 15 is orthogonal to the moving direction 58 of the substrate 30. In a plan view, the long beam cross section 18A is arranged parallel to the nozzle row 15A. The beam profile 18A is longer than the nozzle array 15A. Therefore, the entire area to which the thermosetting ink discharged from the inkjet head 15 is attached can be heated by irradiating the laser. Next, the operation of the film forming apparatus according to this embodiment will be described. After the control device 20 is heated by the laser light source 16 in a local area of the substrate 30, the moving mechanism 13 operates so as to pass under the inkjet head 15. Thereby, a local area of the substrate 30 is heated in a non-contact manner by the laser light source 16, and thereafter, 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 cross section, and the moving speed of the substrate 30 are set so that the surface temperature of the substrate 30 when the ink is adhered to the substrate 30 is maintained above the curing temperature of the ink. Therefore, the ink discharged from the inkjet head 15 is cured as soon as it is attached to the substrate 30. The substrate 30 is moved relative to the laser light source 16 and the inkjet head 15, so that the heating area and the area where the thermosetting ink is attached move 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 embodiment will be described. In the above embodiment, a thermosetting ink is used for forming a film. Generally, compared with ultraviolet curable inks, thermosetting inks are excellent in adhesion and chemical resistance to various raw materials and have low viscosity. For example, a low-viscosity thermosetting ink capable of stably ejecting ink from the inkjet head 15 at room temperature can be obtained. Therefore, it is not necessary to prepare an ink heating device for reducing ink viscosity. Further, in the above embodiment, the laser light source 16 is used to locally heat the substrate 30. For example, the table 10 (FIG. 1A) can be provided with a hot plate function to heat the entire substrate 30 substantially uniformly. However, in this method, it is necessary to wait for a long time after heating the substrate 30 to the target temperature after holding the substrate 30 on the stage 10. In this embodiment, there is no need for a waiting time for heating, so it is possible to avoid a decrease in the 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, the substrate 30 is heated in a non-contact manner without the need to heat the table 10, so it is possible to avoid a reduction in mechanical accuracy. Immediately after the ink is attached to the substrate 30, if a laser beam is incident on 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 is adhered, so that the ink is not scattered. In addition, since the ink adheres to the substrate 30 and immediately begins to cure, it is possible to prevent the ink from being excessively diffused or bleeding. Next, a modification of the above embodiment will be described. In the above embodiment, the laser light source 16 (FIG. 1B) is used as the non-contact heating member, but a heating device capable of locally heating the substrate 30 in a non-contact manner may be used. For example, a device for heating by light energy such as a light emitting diode (LED) or a high-frequency induction heating device can be used. In the above embodiment, the substrate 30 is moved relative to the laser light source 16 and the inkjet head 15. On the contrary, the laser light source 16 and the inkjet head 15 may be moved relative to the substrate 30. Furthermore, in the above embodiment, the laser beam output from the laser light source 16 is a continuous wave laser beam, but it may be a pulsed laser beam. In the above-mentioned embodiment, the nozzle row 15A (FIG. 1C) is made orthogonal to the moving direction 58 (FIG. 1C) of the substrate 30, but it does not have to be orthogonal. The nozzle rows 15A may be intersected with respect to the moving direction 58 of the substrate 30. Next, a simulation result of a temperature change when a laser beam is incident on a substrate having a copper foil will be described with reference to FIGS. 2A to 2C. FIG. 2A is a cross-sectional view of a substrate 50 as a simulation target. The substrate 50 has a three-layer structure including an epoxy substrate 51 having a thickness of 800 μm, a copper foil 52 having a thickness of 30 μm, and an epoxy layer 53 having a thickness of 10 μm. In the embodiment shown in FIGS. 1A to 1C, the resin film 32 (FIG. 1A) is not formed on the substrate 30 when the laser beam is irradiated, but the ink adhered to the substrate 30 needs to be heated to the curing temperature. In the simulation, the epoxy layer 53 corresponding to the ink adhered to the substrate 30 was included in the heating target. FIG. 2B is a diagram showing a positional relationship between a beam spot 56 on the surface of the substrate 50 and a specific portion 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 portion 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 taken for the laser beam to irradiate the specific portion 55 becomes 2.5 ms. The total energy of the laser beam is assumed to be absorbed in the simulation. FIG. 2C is a graph showing a simulation result of the temperature change on the surface of the copper foil 52 at the specific portion 55. The horizontal axis represents the elapsed time in the unit "ms", and the vertical axis represents the temperature in the unit "° C". When the laser beam starts to enter the specific location 55, the temperature rises, and the highest temperature exceeds 250 ° C. The time exceeding 150 ° C is about 5ms. When the laser beam is irradiated, the temperature decreases sharply to about 120 ° C, but thereafter the temperature decreases slowly. It is considered that the temperature at which 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 a thermosetting ink can be cured if the temperature at which the temperature decrease becomes slower is higher than the curing temperature of the ink. From the simulation results shown in FIGS. 2A to 2C, it is considered 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 performed 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 808 nm, a beam spot diameter of 0.5 mm, and a substrate moving speed of 200 mm / s, the heated copper foil was sprayed with a thermosetting ink. As a result, it can be confirmed that the thermosetting ink is cured in the area irradiated with the laser. Next, referring to FIG. 3, a preferred wavelength of a laser beam used for heating will be described. FIG. 3 is a graph showing the wavelength dependence of the reflectance of electrolytically polished gold, silver, and copper. The horizontal axis represents the wavelength in the unit "nm", and the vertical axis represents the reflectance. In order to efficiently heat the metal foil on the substrate, it is preferable to use a laser beam in a wavelength region having a low reflectance. As can be seen from FIG. 3, for example, when a copper foil is provided on the substrate surface, it is preferable to use a laser beam in a wavelength range of 570 nm or less. It can be seen that when gold foil is provided on the substrate surface, it is preferable to use a laser beam in a wavelength range of 520 nm or less. It can be seen that when a silver foil is provided on the substrate surface, it is preferable to use a laser beam in a wavelength range of 350 nm or less. Next, a film forming apparatus according to another embodiment will be described with reference to FIGS. 4A and 4B. In the following, descriptions of structures common to the embodiments shown in FIGS. 1A to 1C will be omitted. FIG. 4A is a schematic side view of a film forming apparatus according to this embodiment. In the embodiment shown in FIG. 1A, the laser light source 16 is disposed on only one side of the inkjet head 15. However, in this embodiment, laser light sources 16 and 17 are disposed on both sides of the inkjet head 15. FIG. 4B is a plan view showing the relative relationship among the inkjet head 15 based on the film forming apparatus of this embodiment, the beam cross sections 18A and 19A based on the laser light sources 16 and 17, and the directions 58A and 58B of the substrate 30 moving. Beam sections 18A and 19A are arranged on both sides of the nozzle row 15A. When the substrate 30 is moved in the direction 58A from the beam cross section 18A to the nozzle row 15A, the beam cross section 18A is operated by the laser light source 16 and the other laser light source 17 is not operated. Conversely, when the substrate 30 is moved in the direction 58B from the beam cross section 19A to the nozzle row 15A, the beam cross section 19A is operated by the laser light source 17 and the other laser light source 16 is not operated. As described above, in this embodiment, when the substrate 30 is moved in any of two directions opposite to each other, the ink can be ejected from the inkjet head 15 to form a film. Next, a film forming apparatus according to another embodiment will be described with reference to FIG. 5. In the following, descriptions of structures common to the embodiments shown in FIGS. 1A to 1C will be omitted. FIG. 5 is a graph showing a light intensity distribution related to the long axis of the beam section 18A. In areas other than the vicinity of both ends in the longitudinal direction, the light intensity is substantially constant. At both ends of the beam profile, the light intensity is higher than in other areas. By setting these light intensity distributions to make up for the lack of temperature rise near both ends of the beam profile 18A, it is possible to heat to a sufficient temperature near both ends. The above embodiments are examples, and it is a matter of course that partial replacement or combination of structures shown in different embodiments can be made. Regarding the same function 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 embodiments described above. For example, it is obvious to those skilled in the art that various changes, improvements and combinations can be made.

10‧‧‧Workbench

11‧‧‧Guide

12‧‧‧Driver

13‧‧‧ mobile agency

15‧‧‧ inkjet head

15A‧‧‧Nozzle row

16, 17‧‧‧ laser light source

18‧‧‧ laser beam

18A, 19A‧‧‧Beam profiles

20‧‧‧Control device

30‧‧‧ substrate

32‧‧‧resin film

50‧‧‧ substrate for simulation

51‧‧‧ epoxy substrate

52‧‧‧copper foil

53‧‧‧epoxy layer

55‧‧‧ specific parts on the substrate

56‧‧‧ Beam Spot

58, 58A, 58B‧‧‧ substrate moving direction

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

Claims (8)

A film forming apparatus includes: a worktable holding a substrate; a inkjet head ejecting thermosetting ink toward the substrate held on the worktable; and a non-contact heating member which is heated and held on the foregoing in a non-contact manner. The aforementioned substrate on the workbench. The film forming apparatus according to item 1 of the scope of patent application, further comprising: a moving mechanism that moves one of the substrate and the inkjet head held on the table relative to the other; and a control device that controls The inkjet head and the moving mechanism, the non-contact heating member heats a partial area of the substrate held on the worktable, the control device controls the movement mechanism and the inkjet head so that the The heated area adheres the thermosetting ink discharged from the inkjet head. The film forming apparatus according to item 1 of the scope of the patent application, wherein the non-contact heating member heats the substrate by causing a laser beam to enter a local area of the substrate held on the table. The film forming apparatus according to item 2 or 3 of the scope of the patent application, wherein the inkjet head includes a nozzle row composed of a plurality of nozzles, and the plurality of nozzles are arranged in a direction crossing the moving direction with respect to the substrate, The region to be heated by the non-contact heating member has an elongated shape parallel to the nozzle row and longer than the nozzle row. The film forming apparatus according to item 3 of the scope of the patent application, wherein the inkjet head includes a nozzle array composed of a plurality of nozzles, and the plurality of nozzles are arranged in a direction crossing the moving direction with respect to the substrate, The region that comes into contact with the heating member and enters the laser beam has an elongated shape parallel to the aforementioned nozzle row, and has a light intensity distribution with light intensity at both ends of the elongated shape being higher than that in other regions. A film forming method includes: (i) a process of heating a local area of a substrate in a non-contact manner; and (ii) a process of forming a film by attaching and curing a thermosetting ink on a heated area of the substrate. The film forming method according to item 6 of the scope of the patent application, wherein in the heating process, a local area of the substrate is heated by making a laser beam incident on the substrate. The film forming method according to item 6 or 7 of the scope of the patent application, wherein the film is formed while moving the heating region and the region where the thermosetting ink adheres within the surface of the substrate.