JP2008119908A - Inkjet liquid droplet nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a stable delivery of a liquid droplet with a liquid droplet diameter of approximately 1 μm by stably feeding a liquid to a needle tip of a delivering electrode. <P>SOLUTION: The amount of feeding of a delivering liquid is controlled by controlling a movement of a needle by providing an ink tank, a plurality of opening parts arranged at specified pitches on a face of a delivering liquid delivering side of the ink tank, a plurality of needles whose tip parts are respectively inserted into the respective opening parts, a bias electric power source loading electric voltage to respective needles and a pulse electric power source, a counter electrode, and a liquid droplet accelerating power source for loading electric voltage to the counter electrode. The tip part of the needle is shaped into a conical needle and a hydrophilic treatment is applied thereon, and the inner wall face of the opening part undergoes a water-repellent treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet droplet nozzle that can be used for printed circuit board wiring, photomask fabrication, lithography, electronic device fabrication, and the like.

  It has been demonstrated that an electrostatic ink jet nozzle combining a capillary and a needle (needle) can form a fine line of 1 micron or less (droplet volume 1 fl) (see Patent Document 1 and Patent Document 2). FIG. 5 is a diagram showing an electrostatically attracting droplet nozzle in which a capillary and a needle described in Patent Document 1 are combined. The electrostatic attraction type droplet nozzle is disposed on the front side of the ink tank, which is a rectangular parallelepiped container, and a discharge liquid supply port is formed on a plate on the rear side of the ink tank.

  The electrostatic attraction type droplet nozzle includes a nozzle body made of a silicon substrate, a plurality of (three shown) discharge electrodes (needles) arranged on a surface of the nozzle body on the discharge liquid discharge side, and a front plate And a capillary fixed to the ink tank. The capillary has a conical cylindrical shape that is gradually tapered along the outer periphery, and its internal space constitutes a part of the liquid flow path and has a liquid discharge port at its tip. The needle is accommodated in the internal space of the corresponding capillary with the needle tip protruding from the liquid discharge port. A gap serving as a liquid flow path for the discharge liquid is formed between the both side surfaces of the nozzle body and the both side plates of the ink tank, and the space between the nozzle body and the plate on the supply port side of the ink tank is the discharge liquid. It has become a liquid storage part.

  A counter electrode having a flat plate shape is disposed at a predetermined position in the liquid discharge direction. A glass substrate for an organic EL display is disposed on the surface of the counter electrode on the nozzle side in a state where the back surface of the substrate is in contact.

  As a method of using the illustrated ink jet type droplet discharge device, first, a discharge liquid is stored in a liquid storage portion in an ink tank, and a voltage from a bias power source is applied to a discharge electrode (needle). Thereby, the discharge liquid stored in the liquid storage part reaches the internal space of the capillary through the gaps on both sides of the nozzle body. In the capillary, the discharge liquid flows along the needle of the discharge electrode to the tip of the corresponding needle. Thus, a droplet having a diameter of about 1 μm is formed at the liquid discharge port. Subsequently, the voltage from the pulse power supply is superimposed on the ejection electrode (needle). Thereby, the fine particles in the liquid droplets at the liquid discharge port are discharged toward the glass substrate for the organic EL display arranged on the counter electrode side.

However, the conventional apparatus as illustrated does not achieve stable ejection of minute droplets because the liquid supply to the needle tip is unstable. The present invention stabilizes the liquid supply to the tip of the needle and realizes the discharge of minute droplets.
Japanese Patent No. 3680855 Japanese Patent No. 3687074

  SUMMARY OF THE INVENTION An object of the present invention is to solve such problems and realize stable discharge of a droplet having a droplet diameter of about 1 micron (1 fl order) by stably supplying a liquid to the needle tip of a discharge electrode. .

  An ink jet droplet nozzle of the present invention includes an ink tank serving as a discharge liquid container, an opening disposed on a discharge liquid discharge side of the ink tank, a needle having a tip inserted into the opening, and A bias power source and a pulse power source for applying a voltage to the needle, a counter electrode, and a droplet accelerating power source for applying a voltage to the counter electrode are provided, and the supply amount of the discharge liquid is controlled by controlling the movement of the needle. Control. This needle is characterized in that the tip is subjected to a hydrophilic treatment with a conical needle shape, and the opening is water repellent on the inner wall surface.

  Further, a needle insertion / removal mechanism for inserting / removing the needle into / from the opening is disposed outside the rear plate opposite to the opening of the ink tank, and drives each needle through a needle through hole formed in the rear plate. As this needle through hole, in order to make a hole slightly larger than the diameter of the wire making the needle and to smooth the movement of the needle and prevent liquid leakage, the inside of the needle through hole and the vicinity of the needle through portion Surface treatment.

  The needle is formed by electrolytic polishing or machining using a metal or semiconductor as a material, and the tip is formed into a needle shape by mechanical polishing in an acid or alkaline solution. The hydrophilic treatment of the needle is realized by forming irregularities on the surface by ion sputtering or chemical etching, and then forming a coating film with titanium oxide or plasma treatment with a chlorine-based gas.

  The water repellent treatment of the inner wall surface of the opening is performed by forming a surface with irregularities on the surface by ion sputtering or chemical etching, and then forming a film of a fluorine compound. The opening is shaped like a conical cylinder with a gradually tapered tip, and the outer wall surface is subjected to the same water repellent treatment as the inner wall surface.

  According to the present invention, by stably supplying a liquid to the tip of a needle as a discharge electrode, lithography of sub-micron to micron order can be realized, so that an electronic device that is cheaper and faster than current photolithography can be manufactured. Can be realized, and direct drawing such as display elements and LSI wiring becomes possible.

  The present invention also provides a water-repellent treatment for using the capillary (hole) as an ink reservoir, and when supplying the liquid from the capillary to the microneedle tip, the liquid is supplied to the needle tip by using a hydrophilic microneedle. Stable supply becomes possible. The distance between the tip of the capillary and the tip of the needle changes with the insertion and removal of the needle, and the supply amount is controlled accordingly. As a result, it is possible to stably discharge micro droplets, and it is possible to control micro droplets according to the properties of the liquid (viscosity, conductivity, dye / pigment, etc.).

  Hereinafter, the present invention will be described based on examples. FIG. 1 is a diagram illustrating an ink jet droplet nozzle constructed according to the present invention. The ink jet droplet nozzle of the present invention includes an ink tank composed of a rectangular parallelepiped container, and a plurality of openings (capillaries) arranged at a predetermined pitch in both the vertical and horizontal directions on the surface of the ink tank on the discharge liquid discharge side. A needle whose tip is inserted into the opening, a needle insertion / removal mechanism for controlling movement thereof, a bias power source and a pulse power source for individually applying a bias power source and a pulse power source to the needle (only one needle is shown) And a counter electrode and a droplet acceleration power source for applying a voltage to the counter electrode. The polarity of the power supply is applied in the opposite direction to the counter electrode and the needle, but depending on the type of discharge liquid, the voltage is in the opposite direction to that shown in the figure. Although not shown, as described above with reference to FIG. 5, the drawing target (for example, a glass substrate for an organic EL display) is disposed on the side facing the needle of the counter electrode. FIG. 1 illustrates a plurality of openings arranged at a predetermined pitch and a plurality of needles into which the tip portions are inserted, respectively. It can also be applied to a droplet nozzle having only one needle.

  The ink tank is formed of an electrically insulating material such as glass, ceramic, or resin in order to obtain electrical insulation from the needle. On the rear plate of the ink tank, a discharge liquid supply port (liquid inlet) is partially formed. The needle insertion / removal mechanism for inserting / removing the needle into / from the capillary is arranged on the rear side of the rear plate opposite to the ink tank opening (hereinafter referred to as the rear side), and each needle (needle) passes through the rear plate. To drive. As a needle through hole, a hole about 100 mm larger than the diameter of the wire making the needle can be produced by, for example, electric discharge machining, drilling, jet machining with sand and water, laser machining, or ultrasonic machining. The inside of the hole is surface treated by using a fluorine compound water repellent to make it water repellent, thereby smoothing the movement of the needle and preventing liquid leakage. The needle also has a surface treatment by making the vicinity of the penetrating portion water-repellent using a fluorine-based water repellent, thereby smoothing the movement of the needle and preventing liquid leakage.

  The discharge liquid is stored in the ink tank configured as described above, and the liquid is supplied to the inside of the capillary, and the liquid repellent effect prevents the liquid from oozing out to the outside of the capillary. In this state, a voltage from a bias power source is applied to each needle. Thereby, the discharge liquid inside the capillary flows to the tip of the needle along the side surface of the needle due to the hydrophilic treatment of the needle surface and the effect of hydrophilization by the electric field. In this way, a liquid having a liquid volume of about 1 fl (droplet diameter converted diameter: 1 μm) is supplied to the needle tip (liquid discharge port). Subsequently, the voltage from the pulse power supply is individually superimposed on the needle (only the bias power supply and pulse power supply for one needle are shown, and the others are not shown). Thereby, the fine particles in the liquid droplets at the liquid discharge port are discharged toward, for example, a glass substrate (not shown) for an organic EL display as a drawing target arranged on the counter electrode side. As shown in the figure, the hole provided in the ink tank itself can be used as a capillary, but its inner wall is surface-treated in the same manner as other capillary examples described later with reference to FIG. The present invention is characterized in that the tip of the needle is made into a conical needle shape and subjected to a hydrophilic treatment, and the inner wall surface of the capillary is subjected to a water repellent treatment. Hereinafter, the needle, the capillary, and the needle insertion / removal mechanism will be further described.

  FIG. 2 is a diagram illustrating the needle. The needle is formed by electrolytic polishing or machining using a metal or semiconductor as a material. For example, a microneedle having a tip diameter of about 20 nm to 50 μm is manufactured by mechanical polishing in an acid or alkali solution. The conical needle-shaped tip is subjected to a hydrophilic treatment with a contact angle of 60 ° or less with water. For example, after forming irregularities on the surface by ion sputtering, chemical etching (wet and dry), forming a film with titanium oxide (dip, spray coating, spin coating) or plasma processing with a chlorine-based gas To achieve a super hydrophilic surface. When the liquid is supplied from the capillary to the needle tip, the liquid can be stably supplied to the needle tip by using a super-hydrophilic fine needle.

  FIG. 3 is a diagram illustrating a capillary. The capillary is formed with a tip hole diameter of 1 to 500 μm using a metal, a semiconductor, or an insulator as a material. As the insulator, ceramic, glass, resin, or fluorine compound is used. The shape of the capillary is illustrated as a conical cylinder shape with the tip portion gradually tapered, but other shapes such as a cylindrical shape, an elliptical column shape, and a polygonal column shape may be used. A plurality of capillaries are arranged in an array or a line as illustrated in FIG. 1 as a single nozzle or as a multi-nozzle. As described above with reference to FIG. 5, the capillary configured as described above can be fixed to the front opening formed in the ink tank via the front plate. By discharging a needle having a conical tip into and out of the capillary, discharge and stop of the liquid are controlled.

  The inner wall of the capillary is water repellent. This is performed by performing water repellent treatment with a contact angle of 60 ° or more with water in order to use the capillaries (holes) as an ink reservoir (to prevent liquid from leaking out). The water-repellent surface is realized by forming irregularities on the surface by ion sputtering and chemical etching (wet and dry) and then forming a film (dip, spray coating, spin coating) with a fluorine compound. Further, in order to prevent ink from seeping out to the outer wall, the outer wall of the capillary is subjected to the same water repellent treatment as that of the inner wall.

  FIG. 4 is a diagram illustrating a needle insertion / removal mechanism. (A) is a figure which shows only the needle taking-in / out mechanism fixed to the needle, (B) is a figure shown in the state which inserted the needle in the capillary. The drive of the needle can be any of mechanical type, electromechanical type, or electric type. For example, the needle is driven by moving the needle tip in and out using a piezo element, by moving the needle in and out by air pressure (piston), or by moving the needle tip in and out by a screw. The distance between the tip of the capillary and the tip of the needle changes as the needle is inserted and removed, and the supply amount is controlled accordingly. The supply can be stopped by protruding the needle tip from the capillary tip surface by a predetermined length. Since the liquid is supplied by utilizing the wettability of the needle, when the needle is protruded and the distance between the liquid surface and the needle tip becomes long, it becomes difficult to supply the liquid to the needle tip. In the case of a multi-nozzle, it is possible to select a nozzle to which liquid is to be discharged by inserting and removing the needle.

It is a figure which illustrates the inkjet type droplet nozzle comprised based on this invention. It is a figure explaining a needle. It is a figure explaining a capillary. It is a figure explaining a needle taking in / out mechanism. It is a figure which shows the electrostatic attraction-type droplet nozzle which combined the capillary and needle (needle) of a prior art.

Claims (7)

An ink tank serving as a discharge liquid container; an opening disposed on the discharge liquid discharge side of the ink tank; a needle having a tip inserted into the opening; a bias power supply for applying a voltage to the needle; In an inkjet droplet nozzle that includes a pulse power source, a counter electrode, and a droplet acceleration power source that applies a voltage to the counter electrode, and controls the supply amount of the discharge liquid by controlling the movement of the needle.
The needle is hydrophilically treated with a conical needle at the tip, and
The opening is water repellent on the inner wall surface,
An ink jet droplet nozzle comprising: A needle insertion / removal mechanism for inserting / removing the needle into / from the opening is disposed outside the rear plate opposite to the opening of the ink tank, and drives each needle through a needle through hole formed in the rear plate. Item 2. The inkjet droplet nozzle according to Item 1. As the needle through-hole, in order to make a hole slightly larger than the wire diameter making the needle, and to smooth the movement of the needle and prevent liquid leakage, the inside of the needle through-hole and the vicinity of the needle through-hole The ink jet droplet nozzle according to claim 2, wherein the surface treatment is performed. 2. The ink jet droplet nozzle according to claim 1, wherein the needle is formed by electropolishing or machining using a metal or semiconductor as a material, and the tip is formed into a needle shape by mechanical polishing in an acid or alkali solution. 2. The ink jet type according to claim 1, wherein the hydrophilic treatment of the needle realizes a hydrophilic surface by forming irregularities on the surface by ion sputtering or chemical etching, and then forming a coating with titanium oxide or plasma treatment with a chlorine-based gas. Droplet nozzle. 2. The ink jet droplet nozzle according to claim 1, wherein the water repellent treatment of the inner wall surface of the opening is performed by forming a concavo-convex surface on the surface by ion sputtering or chemical etching and then forming a coating film with a fluorine compound. 7. The ink jet droplet nozzle according to claim 6, wherein the opening has a conical cylindrical shape with a gradually tapered tip end portion, and the outer wall surface is subjected to the same water-repellent treatment as the inner wall surface.

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