KR20190132986A - Film Forming Device and Film Forming Method - Google Patents

Abstract

The substrate is held on the table. The inkjet head ejects the thermosetting ink toward the substrate held on the table. Non-contact heating means heats the substrate held on the table in a non-contact manner. By doing in this way, an ink can be hardened rapidly, 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.

Background Art A device for drawing a photocurable (ultraviolet curable) ink from an inkjet head or the like and drawing a recording medium such as a substrate is known (Patent Document 1). After disposing the ultraviolet curable ink on the recording medium, the ink can be cured quickly by irradiating an appropriate amount of ultraviolet light.

Patent Document 1: Japanese Unexamined Patent Publication No. 2008-188983

UV-curable inks used for solder resist applications of printed boards have a higher viscosity than conventional inks. For this reason, it is preferable to lower a viscosity to the extent that ink can be discharged from an inkjet head by heating the ink supplied to an inkjet head. If the temperature of the ink becomes too high, the deterioration of the ink is accelerated. If the temperature of the ink is too low, the viscosity of the ink becomes higher than the target viscosity, so that the ejection of the ink 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 which can quickly cure an ink without using a photocurable ink.

According to one aspect of the present invention,

A table holding a substrate,

An inkjet head for discharging thermosetting ink toward the substrate held on the table;

A film forming apparatus having non-contact heating means for non-contact heating of the substrate held on the table is provided.

According to another aspect of the present invention,

Heating a portion of the substrate in a non-contact manner;

A film forming method having a step of forming a film by attaching and curing a thermosetting ink to a heated region of the substrate is provided.

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

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

1A to 1C, a film forming apparatus according to an embodiment will be described.

1A is a schematic side view of a film forming apparatus according to the present embodiment. The table 10 holds the substrate 30 on its upper surface. The table 10 has, for example, a vacuum chuck mechanism, and absorbs 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 the non-contact heating means irradiates a laser beam to the substrate 30 held on the table 10, thereby heating a portion of the substrate 30 in a non-contact manner.

The moving mechanism 13 moves one of the board | substrate 30 and the inkjet head 15 hold | maintained by 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 for guiding the table 10 in one direction, and a drive unit 12 for moving the table 10 along the guide 11.

The controller 20 controls the ejection of the ink from the inkjet head 15. Moreover, the control apparatus 20 moves the table 10 at a target speed by controlling the drive part 12. In the control apparatus 20, pattern data defining the planar shape of the film to be formed is stored. The controller 20 controls the inkjet head 15 and the moving mechanism 13 based on the pattern data, thereby attaching the thermosetting ink to a desired location on the upper surface of the substrate 30 to form the resin film 32. can do.

1B is a perspective view of the laser light source 16. The laser light source 16 outputs the laser beam 18 whose beam cross section 18A is elongate. As the laser light source 16, a laser diode (LD) bar provided with a water cooling mechanism can be used. For example, by arranging five LD bars having an array width of 10 mm, LD bars having an array width of 50 mm are obtained. The oscillation wavelength of the laser light source 16 is 808 nm, for example, and the beam cross section is a long shape whose dimension of a major axis direction is about 50 mm. The movement direction of the substrate 30 at the time of film formation and the major axis direction of the beam cross section are orthogonal to each other. The diffusion angle in the minor axis direction is about 1 ° including the lens, and the beam size in the minor axis direction on the substrate 50 mm apart is about 1.5 mm. The output of the laser light source 16 is set to the magnitude | size which can raise the temperature of the board | substrate 30 to the target temperature.

1C is a plan view showing the relative relationship between the inkjet head 15, the beam end surface 18A of the laser beam, and the moving direction 58 of the substrate 30. As shown in FIG. The nozzle row 15A including the plurality of nozzle holes of the inkjet head 15 is orthogonal to the moving direction 58 of the substrate 30. In plan view, the elongate beam end face 18A is disposed parallel to the nozzle row 15A. The beam cross section 18A is longer than the nozzle row 15A. For this reason, the whole area | region to which the thermosetting ink discharged | emitted from the inkjet head 15 adheres can be heated by laser irradiation.

Next, the operation of the film forming apparatus according to the present embodiment will be described.

The controller 20 operates the moving mechanism 13 to pass under the inkjet head 15 after a portion of the substrate 30 is heated by the laser light source 16. As a result, a part of the region of the substrate 30 is heated in a non-contact manner by the laser light source 16, and then ink ejected from the inkjet head 15 is attached to the heated region. The power density of the laser beam, the dimension 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. . For this reason, the ink discharged from the inkjet head 15 is cured immediately after being attached to the substrate 30.

By moving the board | substrate 30 with respect to the laser light source 16 and the inkjet head 15, the area | region to heat and the area | region to which thermosetting ink adheres move in the surface of the board | substrate 30. As shown in FIG. Thereby, the resin film 32 which hardened the thermosetting ink on the surface of the board | substrate 30 can be formed.

Next, the excellent effect of the said Example is demonstrated.

In this embodiment, a thermosetting ink is used for film formation. In general, thermosetting inks have better adhesion and chemical resistance to various materials and lower viscosity than UV-curable inks. For example, it is possible to obtain a thermosetting ink having a low viscosity such that ink can be stably discharged from the inkjet head 15 at room temperature. For this reason, it is not necessary to prepare the ink heating apparatus for reducing the viscosity of ink.

In the above embodiment, the substrate 30 is locally heated using the laser light source 16. For example, it is possible to give the table 10 (FIG. 1A) a hot plate function, and to heat the whole board | substrate 30 substantially uniformly. In this method, however, the substrate 30 must be held on the table 10 and then waited for a long time until it is heated to a target temperature. In this embodiment, since no waiting time for heating is required, a decrease in throughput due to the heat treatment can be avoided.

In addition, when the table 10 itself is heated, it becomes difficult to maintain the mechanical precision of the table 10 and the moving mechanism 13 under the influence of thermal expansion. In this embodiment, since the board | substrate 30 is heated non-contact without heating the table 10, the fall of a mechanical precision can be avoided.

Immediately after the ink was attached to the substrate 30, when the laser beam was made to enter the ink attachment point and the substrate was heated, a phenomenon in which the ink was scattered due to the high energy of the laser beam was confirmed. In this embodiment, since the substrate 30 is heated before the ink is attached, the ink does not scatter. In addition, since the ink starts curing immediately when the ink adheres to the substrate 30, excessive spreading or spreading of the ink can be prevented.

Next, the modification of the said Example is demonstrated. Although the laser light source 16 (FIG. 1B) was used as a non-contact heating means in the said Example, you may use the heating apparatus which can locally heat the board | substrate 30 non-contact. For example, it is also possible to use an apparatus for heating by light energy such as a light emitting diode (LED), or a high frequency induction heating apparatus.

In the above embodiment, the substrate 30 is moved relative to the laser light source 16 and the inkjet head 15, but the laser light source 16 and the inkjet head 15 may be moved relative to the substrate 30. . In the above embodiment, the laser beam output from the laser light source 16 is a continuous wave laser beam, but may be a pulsed laser beam.

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

Next, with reference to FIGS. 2A-2C, the simulation result of the temperature change at the time of injecting a laser beam into the board | substrate with copper foil is demonstrated.

2A is a cross-sectional view of the substrate 50 to be simulated. The substrate 50 has a three-layer structure consisting of 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 at the time of irradiating the laser beam, but the ink adhered to the substrate 30 to the curing temperature. Since it is necessary to heat, in the simulation, the epoxy layer 53 corresponding to the ink attached to the substrate 30 was included in the heating target.

2B is a diagram illustrating 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 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 location 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 which the laser beam is irradiated to the specific location 55 is 2.5 ms. In the simulation, it is assumed that the total energy of the laser beam is absorbed.

2C is a graph showing a simulation result of a temperature change of the surface of the copper foil 52 at the specific location 55. The horizontal axis represents elapsed time in units of "ms", and the vertical axis represents temperature in units of "° C". When the incidence of the laser beam at the specific location 55 starts, the temperature rises, and the maximum achieved temperature exceeds 250 ° C. The time exceeding 150 degreeC is about 5 ms.

When irradiation of a laser beam is complete | finished, temperature will fall rapidly to about 120 degreeC, but the temperature fall after that is moderate. It is considered that the temperature at the time when the temperature decreases slowly varies depending on the power density of the laser beam and the irradiation time (the size of the beam spot 56). It is thought that a thermosetting ink can be hardened | cured if the temperature at the time when temperature fall is slow is more than the curing temperature of 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 result of the simple preliminary experiment performed in order to confirm that a thermosetting ink can be hardened is demonstrated. After irradiating a laser beam to copper foil on the conditions of the wavelength of 808 nm, the beam spot diameter of 0.5 mm, and the moving speed of 200 mm / s of a board | substrate, the thermosetting ink was spray-sprayed on the heated copper foil. As a result, it was confirmed that the thermosetting ink was cured in the laser irradiated region.

Next, with reference to FIG. 3, the preferable wavelength of the laser beam used for heating is demonstrated.

3 is a graph showing wavelength dependence of reflectances of electropolished gold, silver and copper. The horizontal axis represents wavelength in units of "nm" and the vertical axis represents reflectance. In order to effectively heat the metal foil on a board | substrate, it is preferable to use the laser beam of the wavelength range with low reflectance. 3 shows that it is preferable to use the laser beam of the wavelength range of 570 nm or less, for example, when copper foil is provided in the board | substrate surface. When gold foil is provided in the surface of a board | substrate, it turns out that it is preferable to use the laser beam of 520 nm or less wavelength range. When silver foil is provided in the surface of a board | substrate, it turns out that it is preferable to use the laser beam of 350 nm or less wavelength range.

Next, a film forming apparatus according to another embodiment will be described with reference to FIGS. 4A and 4B. Hereinafter, description is abbreviate | omitted about the structure common to the Example shown to FIG. 1A-FIG. 1C.

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

4B shows the ink jet head 15 of the film forming apparatus according to the present embodiment, the beam end surfaces 18A and 19A by the laser light sources 16 and 17, and the directions 58A and 58B in which the substrate 30 moves. It is a top view which shows the relative relationship with a. Beam end surfaces 18A and 19A are disposed on both sides of the nozzle row 15A, respectively.

When the substrate 30 is moved in the direction 58A from the beam end face 18A toward the nozzle row 15A, the laser light source 16 for the beam end face 18A is operated to operate the other laser light source 17. Does not work. In contrast, when the substrate 30 is moved in the direction 58B from the beam end face 19A toward the nozzle row 15A, the laser light source 17 for the beam end face 19A is operated to operate the other laser light source ( 16) do not operate.

As described above, in this embodiment, even when the substrate 30 is moved in any of two directions opposite to each other, the film can be formed by ejecting ink from the inkjet head 15.

Next, a film forming apparatus according to another embodiment will be described with reference to FIG. 5. Hereinafter, description is abbreviate | omitted about the structure common to the Example shown to FIG. 1A-FIG. 1C.

5 is a graph showing the light intensity distribution in the long axis direction of the beam cross section 18A. In the region other than the vicinity of both ends in the major axis direction, the light intensity is substantially constant. At both ends of the beam cross section, the light intensity is higher than that of other regions. By setting it as such light intensity distribution, the lack of the temperature rise in the vicinity of the both ends of the beam cross section 18A can be compensated, and it can heat to sufficient temperature also in the vicinity of both ends.

Each embodiment mentioned above is an illustration, It goes without saying that partial substitution or combination of the structure shown by another embodiment is possible. The same working effect by the same structure of several embodiment is not mentioned separately by embodiment. In addition, the present invention is not limited to the above-described embodiment. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

10 tables
11 guide
12 drive
13 moving mechanism
15 inkjet heads
15A Nozzle Row
16, 17 laser light source
18 laser beam
18A, 19A beam cross section
20 controls
30 boards
32 resin film
50 substrate to be simulated
51 Epoxy Substrate
52 copper foil
53 Epoxy Layer
55 Specific points on the substrate
56 beam spot
58, 58A, 58B substrate direction of travel

Claims (8)

A table holding a substrate,
An inkjet head for discharging thermosetting ink toward the substrate held on the table;
And non-contact heating means for heating the substrate held on the table in a non-contact manner. The method of claim 1,
A transfer mechanism for moving the substrate held on the table and one of the inkjet heads with respect to the other;
And a control device for controlling the inkjet head and the moving mechanism,
The non-contact heating means heats an area of a portion of the substrate held on the table,
And the control device controls the moving mechanism and the ink jet head to attach the thermosetting ink discharged from the ink jet head to a region heated by the non-contact heating means. The method of claim 1,
And the non-contact heating means heats the substrate by injecting a laser beam into a portion of the substrate held by the table. The method according to claim 2 or 3,
The inkjet head includes a nozzle array comprising a plurality of nozzles arranged in a direction crossing with respect to a moving direction of the substrate,
An area heated by the non-contact heating means has a long shape parallel to the nozzle row and longer than the nozzle row. The method of claim 3,
The inkjet head includes a nozzle array comprising a plurality of nozzles arranged in a direction crossing with respect to a moving direction of the substrate,
The region in which the laser beam is incident by the non-contact heating means has a long shape parallel to the nozzle row, and a film having a light intensity distribution at both ends of the long shape that is higher than the light intensity in other regions. Forming device. Heating a portion of the substrate in a non-contact manner;
And forming a film by attaching and curing a thermosetting ink to the heated region of the substrate. The method of claim 6,
In the heating step, a film forming method of heating a portion of the substrate by injecting a laser beam into the substrate. The method according to claim 6 or 7,
The film forming method of forming the film while moving the region to be heated and the region to which the thermosetting ink is adhered within the surface of the substrate.

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