JP2007260576A - Coating apparatus and coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating apparatus and a coating method which enable an efficient coating by jetting droplets with good controllability. <P>SOLUTION: The coating apparatus comprises a substrate made of a piezoelectric material, an electrode formed on the substrate for oscillating surface acoustic wave, and a liquid storage chamber formed on the substrate and having a discharge port and the liquid in the liquid storage chamber is discharged through the discharge port by the surface acoustic wave transmitted on the surface of the substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coating apparatus and a coating method, and more particularly to a coating apparatus and a coating method for discharging a liquid by surface acoustic waves.

  As an inkjet apparatus used for printing or the like, for example, a piezo-type inkjet apparatus is widely used. In a piezo-type ink jet device, liquid is ejected by expansion and contraction of the piezo element, so that the liquid ejected from the liquid storage unit is droplets. The size of the droplet is affected by the capacity of the liquid storage section, the diameter of the pore from which the droplet is discharged, the amount of charge, and the like. For this reason, it is insufficient as a coating apparatus for a large area substrate. There is also a problem that it is difficult to adjust the discharge direction and the discharge area.

  In order to accurately discharge a liquid, there is a technical disclosure example of a pipette that generates surface acoustic waves on a propagation surface and discharges and flies the liquid guided to the end of the propagation surface as a mist (Patent Document 1).

However, even in this disclosed example, it is difficult to control the amount, direction, discharge position, discharge area, and the like of droplets to be discharged, which are important for application apparatus applications.
JP 2001-212469 A

  An object of the present invention is to provide a coating apparatus and a coating method capable of ejecting droplets with good controllability and applying them efficiently.

  According to one aspect of the present invention, the apparatus includes a substrate made of a piezoelectric material, an electrode provided on the substrate and exciting a surface acoustic wave, and a liquid storage chamber provided on the substrate and having a discharge port. The application apparatus is characterized in that the liquid in the liquid storage chamber is discharged from the discharge port by surface acoustic waves propagating on the surface of the substrate.

  According to another aspect of the present invention, when the high frequency power including the resonance frequency of the surface acoustic wave is applied to the electrode using the coating apparatus, the frequency modulation, the amplitude modulation, and the frequency sweep are selected. By performing either one of the methods, an application method is provided in which the liquid is applied to a specific region while changing the discharge angle of the liquid in a specific axis direction.

  According to the present invention, it is possible to provide a coating apparatus and a coating method that can finely adjust the ejection of droplets and that can be efficiently coated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are schematic views illustrating a coating apparatus 1 according to a first specific example of the present invention, in which FIG. 1A is a schematic cross-sectional view, and FIG. 1B is a line AA in FIG. It is a schematic cross section along the line.

  The coating apparatus 1 mainly includes a substrate 2 made of a piezoelectric material capable of propagating a surface acoustic wave (SAW), and a comb electrode (IDT: Inter Digital Transducer) 3 formed on the main surface of the substrate 2. And an oscillator 5 for exciting the comb-tooth electrode 3, and a liquid storage chamber 7 provided so as to cover the one main surface of the substrate 2 and the comb-tooth electrode 3.

As the substrate 2, for example, a plate-like substrate made of a piezoelectric single crystal such as 128 ° Y-cut LiNbO ₃ can be used. The comb electrode 3 is made of, for example, a metal film such as Au or Al and has a comb shape so that a surface acoustic wave can be excited. Since this electrode pattern is generally fine, it is formed by a lithography method or the like. Both ends of the comb electrode 3 are connected to the oscillator 5 via the electrode pads 4. The oscillator 5 oscillates at a resonance frequency determined from the type of the piezoelectric single crystal substrate 2 and the period of the comb electrode 3 and supplies power to the comb electrode 3 continuously or intermittently. When power higher than a specific power is applied to the oscillator 5, the piezoelectric single crystal substrate 2 immediately below the comb electrode 3 is excited, and surface acoustic waves are generated on the main surface of the piezoelectric single crystal substrate 2.

  A liquid storage chamber 7 is provided so as to cover the comb electrode 3 and the propagation surface of the substrate 2. A liquid 9 maintained at a specific pressure is supplied from a supply port 8 provided in the liquid storage chamber 7, and the liquid storage chamber 7 can be filled with the liquid 9. Further, the liquid 9 is appropriately discharged from the discharge port 13 provided on the side facing the supply port 8. Further, as illustrated in FIG. 1A, a fine slit or hole for discharging the liquid 9 is provided in the lower part of the liquid storage chamber 7 and in the vicinity of the end portion of the surface acoustic wave propagation surface. The discharge port 10 is provided.

  In the coating apparatus 1 according to this example, the insulating film 11 is formed so as to cover the upper surfaces of the comb-tooth electrode 3 and the substrate 2 in the liquid storage chamber 7. In this case, the insulating film 11 is provided up to the vicinity of the ejection port 10. In other words, the insulating film 11 is formed up to a position retracted slightly inward from the ejection port 10. As a result, the substrate 2 in the liquid storage chamber 7 includes a region covered with the insulating film 11 and a region in contact with the liquid 9 instead of the insulating film 11.

  When electric power from the oscillator 5 is applied to the electrode pad 4, the piezoelectric single crystal substrate 2 is excited to generate a surface acoustic wave. The surface acoustic wave propagates through the interface between the substrate 2 and the insulating film 11 from the comb-tooth electrode 3 toward the end of the substrate 2 where the slit-like discharge port 10 is provided. When the surface acoustic wave reaches a region where the substrate 2 is not covered with the insulating film 11, the surface acoustic wave acts on the contacted liquid 9. At this time, the Rayleigh wave of the surface acoustic wave exerts a continuous force on the liquid 9 in a specific direction determined by the oscillation period. By this force, the liquid 9 is discharged from the discharge port 10 and applied to the application surface.

Here, the influence of the insulating film 11 when the Rayleigh wave among the surface acoustic waves propagates through the upper surface of the substrate 2 will be described.
FIG. 2 is a schematic diagram showing a state in which Rayleigh waves propagate on the substrate 2 covered with the insulating film 11.
FIG. 3 is a schematic diagram showing a state in which Rayleigh waves propagate on the substrate 2 not covered with the insulating film 11 as a comparative example.

  First, it can be seen from the comparative example shown in FIG. 3 that the Rayleigh wave L is greatly attenuated as the Rayleigh wave L propagates along the direction A in which the surface acoustic wave propagates. That is, since the substrate 2 is not covered with the insulating film 11, the Rayleigh wave L directly acts on the interface of the liquid 9 (force F) and is absorbed. As a result, the Rayleigh wave L that has reached the vicinity of the discharge port 10 has already been greatly attenuated, and the force necessary to discharge the liquid 9 cannot be effectively applied.

  On the other hand, as shown in FIG. 2, in the coating apparatus 1 according to this specific example, the insulating film 11 is formed to a position retracted slightly inward from the discharge port 10. The substrate 2 includes a region R1 covered with the insulating film 11 and a region R2 in contact with the liquid 9 instead of the insulating film 11. The Rayleigh wave L first propagates along the propagation direction A along the interface between the substrate 2 and the insulating film 11 in the region R1. In the region R1, since the Rayleigh wave L is not in contact with the liquid 9, the attenuation of the Rayleigh wave can be suppressed. As a result, the Rayleigh wave that has reached the region R <b> 2 can effectively act on the liquid 9 with a force F sufficient to be discharged.

  That is, it is possible to prevent the Rayleigh wave from being attenuated by the liquid 9 by covering most of the propagation path of the surface acoustic wave (Rayleigh wave) with the insulating film 11. As a result, the energy of the Rayleigh wave L can be maintained up to the vicinity of the ejection port 10, and the force F necessary for the Rayleigh wave L to eject the liquid 9 can be effectively applied.

  It is also easy to finely adjust the discharge amount and discharge direction of the liquid 9 to be discharged. For example, by controlling the position of the end face of the insulating film 11, the point of action of Rayleigh waves on the liquid 9 can be controlled. That is, when the distance X from the second side surface of the liquid storage chamber 7 to the insulating film 11 is changed, the action point of the Rayleigh wave to the liquid 9 and the magnitude of the force at which the Rayleigh wave acts on the liquid 9 change. Therefore, the discharge direction and the discharge amount of the liquid 9 can be accurately controlled.

  Furthermore, the insulating film 11 also has a function of preventing the comb electrode 3 from being damaged. When the liquid 9 in the liquid storage chamber 7 is conductive, if the comb electrode 3 and the liquid 9 are in direct contact, an electrical short circuit may occur, or etching or corrosion may damage the comb electrode 3. There is also sex. On the other hand, by providing the insulating film 11 on the comb electrode 3, damage to the comb electrode 3 can be prevented.

  The main effects of the insulating film 11 have been described above. The discharge direction and the discharge amount of the liquid 9 from the discharge port 10 can also be controlled by the oscillator 5. That is, arbitrary power is supplied from the oscillator 5 to the comb electrode 3 continuously or intermittently. At that time, the force acting on the liquid 9 varies by performing voltage modulation or sweep in a specific power range or frequency modulation or sweep in a specific frequency range. As a result, since the relationship between the force in a specific direction generated by the Rayleigh wave and the gravity changes, the discharge direction of the liquid 9 can be continuously changed by a minute amount. If this is performed continuously, a specific area can be applied. Further, if these power and frequency are arbitrarily adjusted, the ejection direction can be adjusted by a minute amount.

  As described above, according to the coating apparatus 1 according to this example, the surface acoustic wave element is used as an oscillation source when a film is formed by discharging a liquid to a specific place on the coating target surface. Acts on the liquid Rayleigh wave. Then, the liquid can be discharged from the discharge port continuously and intermittently onto the application target surface, and a film can be efficiently formed at an arbitrary place. By controlling the oscillation power, the discharge angle is changed, the application area per element is widened, and continuous discharge is possible. Therefore, it is possible to expect an improvement in productivity by shortening the application time.

  Further, since most of the propagation path of the surface acoustic wave (Rayleigh wave) is covered with the insulating film 11, it is possible to prevent the Rayleigh wave from being attenuated by the liquid 9, so that the power applied to the oscillator 5 can be reduced. . That is, the power consumption of the coating apparatus can be reduced. Further, by controlling the end face of the insulating film 11, it is easy to finely adjust the discharge amount and discharge direction of the liquid 9 to be discharged.

Further, by using a surface acoustic wave element that is less expensive than a piezo-type ink jet unit, a coating apparatus can be provided at a low cost.
The coating apparatus according to this example can be used not only as a printer but also in various coating processes in fine processing of semiconductor devices, manufacturing of liquid crystal display devices, and the like.

Next, a second specific example of the present invention will be described.
FIG. 4 is a schematic view illustrating the coating apparatus 1 according to the second specific example of the invention. 4A is a schematic cross-sectional view of the coating apparatus 1 according to the present embodiment, and FIG. 4B is a schematic cross-sectional view along the line BB in FIG. 4A.
In the coating apparatus of this specific example, the size of the liquid storage chamber 7 is different from the coating apparatus according to the above-described embodiment. That is, in this coating apparatus, the comb electrode 3 is disposed outside the liquid storage chamber 7, and the liquid storage chamber 7 is provided only on the upper surface of the substrate 2 that is a propagation path of the surface acoustic wave.

Also in this specific example, the insulating film 11 covers most of the surface acoustic wave propagation surface (substrate 2) and the upper surface of the comb electrode 3. As a result, as in the specific example described above, when a constituent material such as the liquid storage chamber 7 is brought into contact with the propagation surface, the surface acoustic wave is attenuated. However, by forming the insulating film 11, the propagation path of the surface acoustic wave is formed. Becomes the interface between the propagation surface and the insulating film 11, so that even if the structural material of the liquid storage chamber 7 is brought into contact with the insulating film 11, the attenuation of the surface acoustic wave is suppressed. As a result, the sealing property of the liquid storage chamber 7 is improved, and the control of the filling of the liquid 9 and the liquid pressure is remarkably improved. Also in this specific example, the comb electrode 3 and the propagation surface (substrate 2) Since the insulating film 11 is formed on the upper surface, the attenuation of Rayleigh waves by the liquid 9 and the damage of the comb-teeth electrode 3 can be prevented, and the same effect as the specific example described above can be obtained.

Next, a third specific example of the present invention will be described.
FIG. 5 is a schematic view illustrating a coating apparatus 1 according to a third specific example of the invention. 5A is a schematic cross-sectional view of the coating apparatus 1 according to this example, and FIG. 5B is a cross-sectional view taken along the line CC in FIG. 5A.

  In the coating apparatus according to this example, the waveguide 12 made of a thin film such as Au or Al is formed on the substrate 2 along the propagation path of the surface acoustic wave. The waveguide 12 extends in the direction parallel to the propagation direction of the surface acoustic wave from the vicinity of the comb electrode 3 toward the discharge port 10, and the output portion of the waveguide 12 communicates with the discharge port 10. The width of the waveguide 12 is formed larger than the intersection width of the comb electrode 3 in the introduction portion of the waveguide 12 (in the vicinity of the comb electrode 3), and is continuous or discontinuous as the discharge port 10 is approached. It is formed to be thin. That is, the width S1 of the introduction portion of the waveguide 12 is larger than the width S2 of the output portion. By forming the waveguide 12 as described above, the surface acoustic wave can be efficiently guided from the vicinity of the comb electrode 3 toward the discharge port 10.

  That is, as in the specific example described above, when the insulating film 11 is formed directly on the propagation surface, the surface acoustic wave propagates through the interface between the insulating film 11 and the propagation surface. For this reason, the surface acoustic wave may be dispersed in a direction other than the propagation direction, such as the insulating film direction or the propagation surface direction, and the directivity of the surface acoustic wave may deteriorate. As a result, attenuation on the Rayleigh wave propagation surface may increase, the force acting on the liquid may be dispersed, the power required for liquid discharge may increase, and the directionality controllability of liquid discharge may deteriorate. .

  On the other hand, when the waveguide 12 is formed on the substrate 2 along the propagation path of the surface acoustic wave as in this specific example, the surface acoustic wave generated by the comb electrode 3 is introduced into the waveguide 12. , And is smoothly propagated to the discharge port 10. As a result, Rayleigh wave attenuation and diffusion can be suppressed. In addition, by controlling the inner diameter of the output portion of the waveguide 12, it is possible to more accurately control the point of action of the Rayleigh wave on the liquid 9. Furthermore, by making the inner diameter of the output portion of the waveguide 12 smaller than the crossing width of the comb electrode 3, the surface acoustic wave is converged, and the power required for liquid ejection can be reduced.

Also in this specific example, since the insulating film 11 is formed on the upper surfaces of the comb electrode 3, the propagation surface (substrate 2), and the waveguide 12, the Rayleigh wave is attenuated by the liquid 9 and the comb electrode 3. Damage can be prevented, and the same effect as the specific example described above can be obtained.
Next, a fourth example of the present invention will be described.
FIG. 6 is a schematic cross-sectional view illustrating a coating unit including a plurality of coating elements according to the fourth specific example of the invention. FIG. 7 is a schematic perspective view showing a coating process using the coating unit according to this example.

  In the coating unit 15 according to this specific example, a plurality of the coating apparatuses 1 according to the specific examples described above are arranged at regular intervals. That is, the coating unit 15 according to this specific example includes a plurality of piezoelectric single crystal substrates 2 arranged at regular intervals, a liquid storage chamber 7 provided between the piezoelectric single crystal substrates 2, and each piezoelectric single crystal substrate 2. And an oscillator 5 connected to the. Comb electrodes 3 and an insulating film 11 are formed on the upper surface of each piezoelectric single crystal substrate 2, and a discharge port 10 is provided at the lower end of each liquid storage chamber 7. The piezoelectric single crystal substrates 2 are arranged in the same direction and at regular intervals so that the propagation surface and the back surface of the adjacent substrates 2 face each other with the discharge ports 10 facing down.

  Thus, according to the coating unit provided with a plurality of coating devices, it is possible to efficiently coat the coating target surface 14 having a large area. Further, since an electric signal can be individually sent from the oscillator 5 to each comb-tooth electrode 3, it is possible to apply only to a specific position on the application target surface. For example, if a plurality of types of ink are filled in each liquid storage chamber 7, color printing by a multi-nozzle head is possible.

  Also in this specific example, since the insulating film 11 is formed on the upper surfaces of the comb-tooth electrode 3 and the propagation surface (substrate 2), attenuation of Rayleigh waves by the liquid 9 and damage to the comb-tooth electrode 3 are prevented. Thus, the same effect as the specific example described above can be obtained.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific examples described above can be combined with each other as far as technically possible, and those obtained in this way are also included in the scope of the present invention. In addition, each specific example and a method of forming the constituent material constituting the specific example can be appropriately selected in consideration of the ease of formation, quality after formation, and the like.

In addition, for example, the piezoelectric single crystal substrate 2 is not limited to LiNbO _3, but a single crystal such as LiTaO ₃ , quartz, Bi1 ₂ GeO ₂ (BGO), piezoelectric ceramics such as PdZrO ₃ , or a piezoelectric film such as ZnO. May be formed on a quartz substrate or the like.

Further, the material of the comb electrode 3 and the waveguide 12 can be formed of a metal film such as Cu in addition to Au and Al. Furthermore, the insulating film 11 may be an inorganic insulating film such as Al ₂ O ₃ or an organic insulating film other than SiO ₂ .

  Further, in order to match the impedance determined by the piezoelectric single crystal substrate 2 and the comb-tooth electrode 3, the oscillator 5 may be provided with a matching circuit including a reactance and a conductance circuit.

It is a schematic diagram which illustrates the coating device which concerns on the 1st specific example of this invention. 4 is a schematic diagram illustrating a state in which Rayleigh waves propagate on a substrate covered with an insulating film 11. FIG. It is a schematic diagram showing a mode that a Rayleigh wave propagates on the board | substrate which is not covered with the insulating film as a comparative example. It is a schematic diagram which illustrates the coating device which concerns on the 2nd specific example of this invention. It is a schematic diagram which illustrates the coating device which concerns on the 3rd example of this invention. It is a schematic diagram which illustrates the coating unit which concerns on the 4th example of this invention. It is a model perspective view showing a mode that it applies using an application unit concerning this example.

Explanation of symbols

1 .... Coating device 2..Piezoelectric single crystal substrate 3 .... Combine electrode 4 .... Electrode pad
5 .... Oscillator 7 .... Liquid storage chamber 8 .... Supply port 9 .... Liquid 10 .... Discharge port 11 .... Insulating film 12 .... Waveguide

Claims (10)

A substrate made of a piezoelectric material;
An electrode provided on the substrate and exciting a surface acoustic wave;
A liquid storage chamber provided on the substrate and having a discharge port;
With
The liquid in the liquid storage chamber is discharged from the discharge port by surface acoustic waves propagating on the surface of the substrate.   The coating apparatus according to claim 1, further comprising an insulating film covering at least an upper portion of the electrode and a region where the surface acoustic wave propagates between the electrode and the discharge port.   The coating apparatus according to claim 1, wherein the insulating film is separated from the discharge port.   The said electrode is provided in the outer side of the said liquid storage chamber, The coating device as described in any one of Claims 1-3 characterized by the above-mentioned.   The coating apparatus according to claim 1, wherein a thin-film waveguide is provided on the substrate between the electrode and the discharge port.   6. The coating apparatus according to claim 5, wherein the width of the waveguide is large in the vicinity of the electrode and small in the vicinity of the discharge port.   The said electrode is a comb-tooth shape, The coating device as described in any one of Claims 1-6 characterized by the above-mentioned.   A coating apparatus comprising a plurality of the coating apparatuses according to any one of claims 1 to 7 juxtaposed. Using the coating apparatus according to any one of claims 1 to 7,
While applying high-frequency power including the resonance frequency of the surface acoustic wave to the electrode, the liquid discharge angle is changed in the specific axis direction by performing any one of frequency modulation, amplitude modulation, and frequency sweep. An application method characterized by applying to a specific area. The coating method according to claim 9, wherein the application position is controlled by adjusting a liquid discharge angle by changing at least one of an application time and an applied voltage of the high-frequency power in the vicinity of the resonance frequency.

Images