JP6925770B2 - Membrane forming device and film forming method - Google Patents

Description

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

A device that ejects photocurable (ultraviolet curable) ink from an inkjet head or the like and draws on a recording medium such as a substrate is known (Patent Document 1). After arranging the ultraviolet curable ink on the recording medium, the ink can be rapidly cured by irradiating an appropriate amount of ultraviolet rays.

Japanese Unexamined Patent Publication No. 2008-188983

Ultraviolet curable inks used for solder resist applications on printed circuit boards have a higher viscosity than ordinary inks. Therefore, it is preferable to reduce the viscosity to the extent that the ink can be ejected from the inkjet head by heating the ink supplied to 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, so that the ink ejection becomes unstable and ink clogging or the like is likely to occur.

An object of the present invention is to provide a film forming apparatus and a film forming method capable of rapidly curing an ink without using a photocurable ink.

According to one aspect of the invention
A table that holds the board and
Have a non-contact heating means for heating the substrate held by the ink-jet head for discharging thermosetting ink toward the substrate held on the table the table in a non-contact,
The inkjet head includes a nozzle array consisting of a plurality of nozzles arranged in a direction intersecting the moving direction of the substrate.
The non-contact heating means heats the substrate by injecting light into a long-shaped region parallel to the nozzle row of the substrate held on the table.
Provided is a film forming apparatus having a light intensity distribution in which the light intensity at both ends of a long shape into which light is incident by the non-contact heating means is higher than the light intensity in other regions.

According to another aspect of the invention
The process of injecting light into a part of the substrate and heating it in a non-contact manner,
By ejecting thermosetting ink from an inkjet head including a nozzle row including a plurality of nozzles, perforated and forming a film by curing by attaching the thermosetting ink to the heated region of the substrate death,
The region in which light is incident in the heating step has a long shape parallel to the nozzle row, and a film is formed in which the light intensity at both ends of the long shape has a light intensity distribution higher than the light intensity in the other regions. The method is provided.

The thermosetting ink can be cured by adhering the thermosetting ink to the region where the substrate is heated by the non-contact means.

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 cross section of an inkjet head, a beam of a laser beam, and a relative to a moving direction of a substrate. It is a top view which shows the relationship. FIG. 2A is a cross-sectional view of the substrate to be simulated, FIG. 2B is a diagram showing a positional relationship between a beam spot on the surface of the substrate and a specific portion on the substrate, and FIG. 2C is a diagram showing the temperature of the specific portion. It is a graph which shows the simulation result of change. FIG. 3 is a graph showing the wavelength dependence of the reflectances of electropolished gold, silver, and copper. FIG. 4A is a schematic side view of the film forming apparatus according to another embodiment, and FIG. 4B shows the relative relationship between the inkjet head of the film forming apparatus according to this embodiment, the beam cross section by the laser light source, and the direction in which the substrate moves. It is a top view which shows. FIG. 5 is a graph showing the light intensity distribution in the long axis direction of the beam cross section of the film forming apparatus according to still another embodiment.

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 the film forming apparatus according to this embodiment. The table 10 holds the substrate 30 on its upper surface. The table 10 has, for example, a vacuum chuck mechanism, and attracts and fixes the substrate 30. 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 means irradiates the substrate 30 held on the table 10 with a laser beam to heat a part 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 with respect 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 table 10 in one direction, and a driving unit 12 that moves the table 10 along the guide 11.

The control device 20 controls the ejection of ink from the inkjet head 15. Further, 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 that defines the planar shape of the film to be formed. By controlling the inkjet head 15 and the moving mechanism 13 based on the pattern data, the control device 20 can attach the thermosetting ink 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 having a long beam cross section 18A. As the laser light source 16, a laser diode (LD) bar with a water cooling mechanism can be used. For example, by arranging five LD bars having an array width of 10 mm, an LD bar having an array width of 50 mm can be obtained. The oscillation wavelength of the laser light source 16 is, for example, 808 nm, and the beam cross section has a long shape having a dimension in the major axis direction of about 50 mm. The moving direction of the substrate 30 at the time of film formation and the long axis direction of the beam cross section are orthogonal to each other. The spread angle in the minor axis direction is about 1 ° with a lens, and the beam size in the minor axis direction on a substrate 50 mm away is about 1.5 mm. The output of the laser light source 16 is set to a size capable of raising 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. The 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, a long beam cross section 18A is arranged parallel to the nozzle row 15A. The beam cross section 18A is longer than the nozzle row 15A. Therefore, the entire area to which the thermosetting ink ejected from the inkjet head 15 adheres can be heated by laser irradiation.

Next, the operation of the film forming apparatus according to this embodiment will be described.
The control device 20 operates the moving mechanism 13 so that a part of the substrate 30 is heated by the laser light source 16 and then passes under the inkjet head 15. As a result, a part of the substrate 30 is heated by the laser light source 16 in a non-contact manner, and then the ink ejected from the inkjet head 15 adheres to the heated region. The power density of the laser beam, the dimensions 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 adheres to the substrate 30 is maintained above the curing temperature of the ink. Therefore, the ink ejected from the inkjet head 15 is cured immediately after adhering to the substrate 30.

By moving the substrate 30 with respect to the laser light source 16 and the inkjet head 15, the region to be heated and the region to which the thermosetting ink is attached move within the surface of the substrate 30. As a result, the resin film 32 on which the thermosetting ink is cured can be formed on the surface of the substrate 30.

Next, the excellent effect of the above embodiment will be described.
In the above embodiment, a thermosetting ink is used for film formation. In general, thermosetting inks have better adhesion to various materials and chemical resistance than ultraviolet curable inks, and have a lower viscosity. For example, it is possible to obtain a thermosetting ink having a low viscosity so that the ink can be stably ejected from the inkjet head 15 at room temperature. Therefore, it is not necessary to prepare an ink heating device for reducing the viscosity of the ink.

Further, in the above embodiment, the substrate 30 is locally heated by using the laser light source 16. 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 from holding the substrate 30 on the table 10 until it is heated to the target temperature. In this embodiment, since the waiting time for heating is not required, it is possible to avoid a decrease in throughput due to heat treatment.

Further, when the table 10 itself is heated, it becomes 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, since the substrate 30 is heated in a non-contact manner without heating the table 10, it is possible to avoid a decrease in mechanical accuracy.

Immediately after the ink was adhered to the substrate 30, when a laser beam was incident on the adhered portion of the ink to heat the substrate, a phenomenon was confirmed in which the ink was scattered due to the high energy of the laser beam. In this embodiment, since the substrate 30 is heated before the ink adheres, the ink does not scatter. Further, since the ink starts to cure as soon as it adheres to the substrate 30, it is possible to prevent excessive spread and bleeding of the ink.

Next, a modified example 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 means, but a heating device capable of locally heating the substrate 30 in a non-contact manner may also be used. For example, a device that heats with light energy such as a light emitting diode (LED), a high frequency induction heating device, or the like can also be used.

In the above embodiment, the substrate 30 is moved with respect to the laser light source 16 and the inkjet head 15, but on the contrary, the laser light source 16 and the inkjet head 15 may be moved with respect to the substrate 30. Further, in the above embodiment, the laser beam output from the laser light source 16 is a continuous wave laser beam, but a pulsed laser beam may be used.

In the above embodiment, the nozzle row 15A (FIG. 1C) is orthogonal to the moving direction 58 (FIG. 1C) of the substrate 30, but it is not always necessary to make the nozzle row 15A (FIG. 1C) orthogonal to the moving direction 58 (FIG. 1C). The nozzle row 15A may be crossed with respect to the moving direction 58 of the substrate 30.

Next, with reference to FIGS. 2A to 2C, a simulation result of a temperature change when a laser beam is incident on a substrate having a copper foil will be described.

FIG. 2A is a cross-sectional view of the substrate 50 to be simulated. 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 examples shown in FIGS. 1A to 1C, the resin film 32 (FIG. 1A) is not formed on the substrate 30 at the time of irradiating the laser beam, but it is necessary to heat the ink adhering to the substrate 30 to the curing temperature. Therefore, in the simulation, the epoxy layer 53 corresponding to the ink adhering 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 was 0.5 mm, the power density of the laser beam on the surface of the substrate 50 was 12 kW / cm ^2, and the moving speed of the substrate 50 was 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 for irradiating the specific portion 55 with the laser beam is 2.5 ms. In the simulation, it was assumed that the total energy of the laser beam was absorbed.

FIG. 2C is a graph showing a simulation result of a temperature change on the surface of the copper foil 52 at a 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 be incident on the specific portion 55, the temperature rises, and the maximum temperature reached exceeds 250 ° C. The time exceeding 150 ° C. is about 5 ms.

When the irradiation of the laser beam is completed, the temperature drops sharply to about 120 ° C., but the subsequent temperature drop is gradual. It is considered that the temperature at the time when the temperature decrease becomes gradual varies depending on the power density of the laser beam and the irradiation time (the size of the beam spot 56). If the temperature at the time when the temperature gradually decreases is equal to or higher than the curing temperature of the ink, it is considered that the thermosetting ink can be cured.

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 conducted 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, a thermosetting ink was sprayed onto the heated copper foil. As a result, it was confirmed that the thermosetting ink was cured in the laser-irradiated region.

Next, a preferable wavelength of the laser beam used for heating will be described with reference to FIG.
FIG. 3 is a graph showing the wavelength dependence of the reflectances of electropolished gold, silver, and copper. 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 in a wavelength range having low reflectance. From FIG. 3, it can be seen that, for example, when a copper foil is provided on the surface of the substrate, it is preferable to use a laser beam in a wavelength range of 570 nm or less. When gold leaf is provided on the surface of the substrate, it can be seen that it is preferable to use a laser beam in a wavelength range of 520 nm or less. When the silver foil is provided on the surface of the substrate, it can be seen that it is preferable to use a laser beam in a wavelength range of 350 nm or less.

Next, the film forming apparatus according to another embodiment will be described with reference to FIGS. 4A and 4B. Hereinafter, the description of the configuration common to the examples shown in FIGS. 1A to 1C will be omitted.

FIG. 4A is a schematic side view of the film forming apparatus according to this embodiment. In the embodiment shown in FIG. 1A, the laser light source 16 is arranged only on one side of the inkjet head 15, but in this embodiment, the laser light sources 16 and 17 are arranged on both sides of the inkjet head 15, respectively. ..

FIG. 4B is a plan view showing the relative relationship between the inkjet head 15 of the film forming apparatus according to the present embodiment, the beam cross sections 18A and 19A by the laser light sources 16 and 17, and the directions 58A and 58B in which the substrate 30 moves. Beam cross sections 18A and 19A are arranged on both sides of the nozzle row 15A, respectively.

When the substrate 30 is moved from the beam cross section 18A to the direction 58A toward the nozzle row 15A, the laser light source 16 for the beam cross section 18A is operated, and the other laser light source 17 is not operated. On the contrary, when the substrate 30 is moved from the beam cross section 19A to the direction 58B toward the nozzle row 15A, the laser light source 17 for the beam cross section 19A is operated, 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 the two directions opposite to each other, 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. Hereinafter, the description of the configuration common to the examples shown in FIGS. 1A to 1C will be omitted.

FIG. 5 is a graph showing the light intensity distribution in the major axis direction of the beam cross section 18A. The light intensity is almost constant in regions other than the vicinity of both ends in the major axis direction. At both ends of the beam cross section, the light intensity is higher than in the other regions. By adopting such a light intensity distribution, it is possible to compensate for the lack of temperature rise in the vicinity of both ends of the beam cross section 18A and to heat to a sufficient temperature even in the vicinity of both ends.

It goes without saying that each of the above embodiments is exemplary and the configurations shown in different examples can be partially replaced or combined. Similar effects and effects due to the same configuration of a plurality of examples will not be mentioned sequentially for each example. Furthermore, the present invention is not limited to the above-mentioned examples. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

10 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 cross section 20 Control device 30 Substrate 32 Resin film 50 Substrate to be simulated 51 Epoxy substrate 52 Copper foil 53 Epoxy Layer 55 Specific location on the substrate 56 Beam spots 58, 58A, 58B Direction of movement of the substrate

Claims (8)

A table that holds the board and
Have a non-contact heating means for heating the substrate held by the ink-jet head for discharging thermosetting ink toward the substrate held on the table the table in a non-contact,
The inkjet head includes a nozzle array consisting of a plurality of nozzles arranged in a direction intersecting the moving direction of the substrate.
The non-contact heating means heats the substrate by injecting light into a long-shaped region parallel to the nozzle row of the substrate held on the table.
A film forming apparatus having a light intensity distribution in which the light intensity at both ends of a long shape into which light is incident by the non-contact heating means is higher than the light intensity in other regions. Moreover,
A moving mechanism for moving one of the substrate held on the table and the inkjet head with respect to the other.
It has the inkjet head and a control device for controlling the moving mechanism.
The non-contact heating means heats a part of the substrate held on the table.
The control device according to claim 1, wherein the control device controls the moving mechanism and the inkjet head so that the thermosetting ink discharged from the inkjet head adheres to a region heated by the non-contact heating means. Membrane forming device. The film forming apparatus according to claim 1 or 2 , wherein the non-contact heating means heats the substrate by injecting a laser beam into a part of a region of the substrate held on the table. The film forming apparatus according to any one of claims 1 to 3, wherein the region heated by the non-contact heating means has a long shape longer than the nozzle row. The film forming apparatus according to any one of claims 1 to 4, wherein the non-contact heating means includes laser light sources arranged on both sides of the nozzle row of the inkjet head. The process of injecting light into a part of the substrate and heating it in a non-contact manner,
By ejecting thermosetting ink from an inkjet head including a nozzle row including a plurality of nozzles, perforated and forming a film by curing by attaching the thermosetting ink to the heated region of the substrate death,
The region in which light is incident in the heating step has a long shape parallel to the nozzle row, and a film is formed in which the light intensity at both ends of the long shape has a light intensity distribution higher than the light intensity in the other regions. Method. The film forming method according to claim 6, wherein in the heating step, a part of the substrate is heated by incident a laser beam on the substrate. The film forming method according to claim 6 or 7, wherein the film is formed while moving the area to be heated and the area to which the thermosetting ink is attached within the surface of the substrate.

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