JP2010279914A - Method and apparatus for ejecting liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus which certainly ejects minute liquid droplets having viscosity of ≥10 cPs onto a substrate with high precision. <P>SOLUTION: A needle having a hollow structure is attached to a liquid storage container and the liquid storage container is compressed by a definite amount to eject liquid having viscosity of ≥10 cPs from a needle tip onto the substrate. In this method for ejecting the liquid, wall thickness (a half of (outer diameter-inner diameter)) of the needle tip is in a range between 0.05 mm and 0.20 mm, the inner diameter of the needle tip is in a range between 0.05 mm and 0.40 mm and an angle made by an extension line of a wall thickness surface of the needle tip and a substrate surface is in a range between 0° and 20°. Thereby dropping of the minute liquid droplets can be achieved with high precision even when the liquid has viscosity of ≥10 cPs. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for ejecting micro droplets of sub-micro order with high accuracy. In particular, the present invention relates to a highly accurate liquid crystal material discharge method in a liquid crystal panel bonding method in which a liquid crystal material is sandwiched between two substrates constituting a liquid crystal panel and bonded via a sealant.

  As one conventional liquid discharge method, there is a method in which a needle having a hollow structure is attached to a liquid storage container called a syringe, and a liquid is discharged from the tip of the needle by pressurizing the liquid storage container by a certain amount. As a means for pressurization, there is compressed air or a mechanical mechanism. In general, a mechanical mechanism is used to realize high-precision discharge in units of 0.00001 m. For example, there is a product made by Musashi Engineering (NANO MASTER SMP III), and it has been described in the catalog of Musashi Engineering that the discharge accuracy of 0.0003 ml has been repeated 30 times without variation in the experiment to discharge water. Yes.

  Further, as an application example of the above-described high-precision dispenser, there is a liquid crystal dropping and bonding method shown in FIG. 6, which is called ODF (ONE DROP FILL) and is used for manufacturing a large-sized liquid crystal panel. The ODF forms a seal on at least one of the two substrates as shown in FIG. 6A, drops the liquid crystal as shown in FIG. 6B, and bonds the two substrates together. As shown in (c), the pressure is applied at atmospheric pressure 6 and the liquid crystal panel is bonded. For example, Patent Document 1 is proposed. In this liquid crystal dropping and bonding method, a high-precision dispenser such as NANO MASTER SMP III is used, a program is created by setting it on a three-axis robot, and a predetermined amount of liquid crystal is dropped.

  ODF has extremely high productivity compared to the vacuum injection method, and has become an indispensable technology especially for the production of large liquid crystal panels of 30 inches or more. Equipment manufacturers include ULVAC and Shibaura Mechatronics. In addition to ODF, a vacuum injection method in which a liquid crystal material is filled from an inlet of a seal is widely adopted for liquid crystal panels of 10 inch class or less.

JP-A-62-89025 (page 8, FIG. 1)

  There are various display principles for liquid crystal panels, but in order to clarify moving image display, development of wide viewing angle and high speed response has been actively conducted. For example, in the case of the TN liquid crystal mode, a method of reducing the liquid crystal cell gap is used as the easiest means for achieving high-speed response. In general, a narrow cell gap of 2 μm or less, preferably about 1.5 μm is required in order to set the response speed of the TN liquid crystal mode to several milliseconds. In recent years, there has been a demand for clear moving image display in 3 to 10 inch class (cell phones, PDAs, notebook computers, etc.) applied products other than large liquid crystal televisions. These 3 to 10 inch class liquid crystal panels have been filled with a liquid crystal material without any problem by a vacuum injection method when the cell gap is 5 to 6 μm. However, even in a 3 to 10 inch size liquid crystal panel, there is a problem that the implantation process becomes extremely long when the cell gap is about 1.5 μm. The injection process for a 4-inch class liquid crystal panel takes about 20 hours, and the 10-inch class liquid crystal panel takes about 50 hours.

  Therefore, an attempt was made to produce a liquid crystal panel by a liquid crystal dropping and bonding method (ODF) as shown in FIG. First, a closed-loop seal 5 was formed on the substrate B2, and the liquid crystal 4 was dropped onto the center with a dispenser [FIG. 7 (a)]. Next, a substrate A1 was bonded together in a vacuum as a counter substrate [FIG. 7B]. Next, pressurization was performed under atmospheric pressure, and mechanical pressurization was attempted from the top and bottom of the substrate with a surface plate to obtain a cell gap of 1.5 μm, but bubbles 11 remained in the corners of the seal 5. It was.

  As a solution for the bubbles 11, as shown in the cross-sectional view of FIG. 8A, an attempt was made to form a closed loop seal 5 on the substrate B <b> 2 and drop the liquid crystal 4 in nine points from the tip of the needle 10. Actually, as shown in the plan view of FIG. 8B, the variation of one drop was extremely large, and accurate weighing of the liquid crystal 4 was impossible. In particular, when the liquid crystal 4 droplets were 0.0010 ml or less, the weighing accuracy was extremely lowered. Here, the distance between the tip of the needle 10 and the substrate B2 was set to 0.03 mm.

  The above-described variation in the weighing of the liquid crystal 4 was caused by the occurrence of the liquid crystal adhesion portion 12 without being discharged from the tip of the needle 10 as shown in FIG. Even for a liquid having a low viscosity of about 1 cP, such as water, even if fine discharge can be obtained without any problem, the liquid crystal material having a viscosity of 10 cP or more frequently causes the problem of the liquid crystal adhesion portion 12.

  In the present invention, focusing on the tip shape of the needle, the needle tip inner diameter, outer diameter, and taper angle of the tip are examined, and a shape that reliably discharges a liquid droplet having a high accuracy and a small viscosity of 10 cP or more to the substrate is ensured. investigated.

  In a liquid discharge method in which a liquid storage container, a needle having a hollow structure, and a liquid storage container are pressurized by a certain amount and a liquid of 10 cP or more is discharged from the tip of the needle onto the substrate, the needle tip thickness (outer diameter-inner diameter) is 0 By making the angle between the extension of the thick surface of the needle tip and the substrate surface 20 ° or less, the liquid can be discharged onto the substrate without adhering to the periphery of the needle tip. Became.

  In addition, by fixing the liquid ejection part consisting of needles to a 3-axis (XYZ axis) robot and vacuum-adsorbing the substrate to a surface plate made of porous ceramic, droplets can be applied to the substrate with an accuracy of 0.00001 ml even in a large area. It became possible to discharge.

  According to the liquid discharge method of the present invention, it is possible to weigh droplets in units of 0.00001 ml even for a liquid having a viscosity of 10 cP or more. In addition, as an application example of the liquid ejection method of the present invention, it becomes possible to drop a liquid crystal material with high precision and a small amount, and stable production of a liquid crystal panel having a narrow cell gap of about 1.5 μm using ODF becomes possible. It was.

  According to the liquid ejection method of the present invention, it is possible to weigh micro droplets in units of 0.00001 ml with respect to a liquid having a viscosity of 10 cP or more. Further, the liquid discharge method of the present invention enables liquid crystal material to be dropped with high accuracy, and stable production of a liquid crystal panel having a narrow cell gap of about 1.5 μm by ODF becomes possible.

It is a schematic explanatory drawing of the liquid dripping method of this invention. It is a schematic flowchart of a liquid crystal panel manufacturing method. It is a schematic explanatory drawing which applied the liquid dripping method of this invention to the liquid crystal panel bonding method. It is a schematic explanatory drawing of the liquid discharge example of the liquid dripping method of this invention. It is a schematic explanatory drawing which applied the liquid dripping method of this invention to the liquid crystal panel bonding method. It is a schematic explanatory drawing of the conventional liquid crystal panel bonding method (ODF). It is a schematic explanatory drawing of the liquid crystal panel produced with the conventional liquid crystal panel bonding method. It is a schematic explanatory drawing of the liquid crystal panel produced with the conventional liquid crystal panel bonding method.

  The best mode of the liquid ejection method of the present invention will be described with reference to FIG.

  FIG. 1A shows the needle 10 attached to the liquid storage container 31 and the tip of the needle 10. The tip of the needle 10 is filled with a liquid 21 having a viscosity of 10 cP. The inner diameter of the needle 10 is D, the thickness of the needle [(outer diameter−½ of inner diameter)] is T, and the taper angle α is defined as shown in FIG. Table 1 shows the results of determining pass / fail by discharging 10 ml of liquid 21 using D, T, and α as parameters, placing the substrate at a distance of 0.03 mm from the tip of the needle, and visually checking the discharge state 30 times.

表１より以下のパラメータ範囲で吐出が良好であることがわかった。

From Table 1, it was found that ejection was good in the following parameter range.

Needle thickness T: 0.05 mm or more Needle taper angle α: 0 to 20 °
According to the best mode of the present invention, as shown in FIG. 4, it is possible to stably discharge fine droplets of the liquid 21 having a viscosity of 10 cP or more from the needle 10 to the substrate B2. Here, the target substrate B2 is formed with a closed-loop seal 5.

  Hereinafter, a liquid ejection method and apparatus according to the present invention will be described in detail with reference to the drawings.

  A liquid ejection method and apparatus according to the first embodiment will be described with reference to FIGS.

  FIG.1 (b) has shown the cross-section of the needle tip part of a hollow structure. The tip part is filled with a liquid 21 having a viscosity of 10 cP. Here, a liquid crystal 4 having a viscosity of 10 cP was used. The inner diameter of the needle is D, the thickness of the needle [(outer diameter−inner diameter) 1/2] is T, and the taper angle α is defined as shown in FIG. The needle material is preferably a surface that repels the liquid 21.

  Next, a schematic flow chart of the liquid crystal panel manufacturing method of FIG. 2 will be described.

  In the substrate cleaning step S1, the substrate A1 and the substrate B2 on which the two desired thin film patterns of the substrate A1 and the substrate B2 are formed are cleaned. In the alignment film forming step S2, an alignment film is formed on the substrate A1 and the substrate B2 by a printing method or an inkjet method. In the alignment processing step S3, alignment processing such as rubbing is performed. In the seal formation step S4, an outer peripheral seal frame hermetically sealed by screen printing or a dispenser is formed on the substrate B2 with the sealant 5 made of UV curable resin. In the liquid crystal dropping step S5, a plurality of accurately weighed volumes of liquid crystal 4 corresponding to the gaps of the liquid crystal panel are dropped into the seal frame. In the spacer spraying step S6, the in-plane spacer 3 is sprayed on the substrate A1, and in the spacer fixing step S7, the in-plane spacer 3 is fixed. Subsequently, in the bonding step S <b> 8, the substrate A <b> 1 and the substrate B <b> 2 are opposed to each other and are bonded together by pressurizing the substrate at atmospheric pressure 6. There is an effect of adjusting the gap of the liquid crystal panel by applying pressure. In the seal curing step S9, the sealing agent 5 is cured by UV and heating to completely bond the substrate A1 and the substrate B2. Further, in addition to the atmospheric pressure 6 as required, the two substrates are further pressurized by the surface plate 54. The substrate manufactured in the substrate separation step S10 is divided into pieces.

  The liquid ejection method and apparatus are configured as described above.

  Results of 0.0005 ml discharge of liquid 21 using needles 10 of various designs shown in Table 1, placing the substrate at a distance of 0.03 mm from the tip of needle 10 and visually checking the discharge state 30 times, and pass / fail judgment results Indicates.

  In Table 1, D represents the inner diameter (mm) of the needle 10, T represents the needle thickness (mm), and α represents the needle taper. Droplet aim (ml) indicates the amount of one drop adhering to the substrate from the tip of the needle. The number of abnormal discharges (number of times) indicates how many abnormalities have occurred in 30 trials. Pass / fail was judged based on whether or not the liquid was deposited on the substrate.

  Here, the number of abnormal ejections when the parameters other than the needle taper angle α are fixed and the taper is set at an interval of 10 ° between 0 ° and 40 ° is described from the first row to the fourth row in Table 1. As shown in the figure, when the needle taper angle α exceeds 30 °, the number of abnormal discharges increases, and when the needle taper angle α is 20 ° or less, the number of abnormal discharges is 0, indicating that it is good.

  Next, the experimental results when the needle thickness T is changed from 0.02 mm to 0.30 mm are shown from the fifth row to the eighth row in Table 1. Here, it can be seen that the number of abnormal ejections is zero and good except for needle thicknesses of 0.02 mm. A needle having a needle thickness of 0.02 mm is equivalent to the conventional needle 10. The conventional needle 10 discharges at least once every two times.

  Furthermore, the experiment results when the needle inner diameter D is changed from 0.03 mm to 0.40 mm are shown in the ninth and subsequent rows of Table 1. Here, it can be seen that when the needle inner diameter D is 0.04 mm or less, the abnormal discharge number can be confirmed, and for the needle inner diameter D of 0.05 mm or more, the abnormal discharge number is 0, which is favorable.

  From the above, it was found that the discharge was good in the following parameter range.

Needle thickness T: 0.05 mm to 0.20 mm
Needle inner diameter D: 0.05 mm to 0.40 mm
Needle taper angle α: 0 ° to 20 °
Further, as an example in Table 2, the needle A (D = 0.15, T = 0.50, α = 0 °) is used 30 times, 2.5 μl is discharged, and an electronic balance (minimum unit: 0.00001 g) ) Shows the data obtained by measuring the weight and calculating the volume from the specific gravity of the material.

表２の結果は平均吐出量２．４９６μｌ、バラツキはσ＝０．０２０６μｌの良好な吐出結果が得られた。ここで、秤量精度を高めるためにはニードル内径が０．０５ｍｍ〜０．４０ｍｍが好ましい。

The results shown in Table 2 were good discharge results with an average discharge amount of 2.496 μl and variation of σ = 0.0206 μl. Here, in order to increase the weighing accuracy, the inner diameter of the needle is preferably 0.05 mm to 0.40 mm.

  In addition to the needle 10 in FIG. 1B, the needle 10 has a cross-sectional shape that is not constant as shown in FIG. 1C and may have a tapered shape.

  The present invention created by the liquid crystal panel bonding method will be described with reference to FIG. Here, the detailed contents of the ODF already described are omitted.

  In the second embodiment, the needle 10 that discharges the liquid 21, the liquid storage container 52 that is connected to the needle 10 and supplies the liquid 21, and the three-axis (XYZ axis) robot 51 that fixes the needle 10 and the liquid storage container 52, The substrate A1 that is a target for discharging the liquid 21 and the surface plate 54 that vacuum-sucks the substrate A1 so as not to be separated.

  The liquid crystal dropping step S5 of Example 2 is shown as follows.

  The substrate A1 was vacuum-sucked by the surface plate 54 so as not to deviate, the dropping position of the needle 10 was adjusted by the three-axis robot 51, and the liquid crystal 4 was dropped at a plurality of points at approximately equal intervals of 0.0025 ml. FIG. 3A shows a liquid crystal panel in which nine points are dropped. The total amount of dripping was 0.0225 ml.

  Then, in bonding process S8, as shown in FIG.3 (b), it bonded to board | substrate A1 which is a counter substrate in a vacuum, and atmospheric pressure was applied, and the uniform gap of 1.5 micrometers was able to be obtained.

  Further, by using a porous ceramic for the surface plate 54, undulation of the substrate due to adsorption is suppressed, and application to a flexible substrate such as a plastic film becomes possible.

  According to the liquid discharge method of the present invention, the liquid 21 having a viscosity of 10 cP or more can be stably discharged with small droplets of 0.00001 ml, and can be applied to a narrow cell gap liquid crystal dropping method (ODF) or the like. In particular, when a liquid crystal panel having a size of 3 to 10 inches and a narrow cell gap of about 1.5 μm is manufactured, a liquid crystal dropping method (ODF) is indispensable. When producing a small-sized liquid crystal panel with a narrow cell gap using ODF, a large number of fine droplets of 10 ml or less must be accurately discharged, and the highly accurate liquid discharge method of the present invention is extremely effective. .

1 Substrate A
2 Substrate B
3 In-plane spacer 4 Liquid crystal 5 Sealing agent 6 Atmospheric pressure 10 Needle 11 Bubble 12 Liquid crystal adhering part 21 Liquid 31, 52 Liquid storage container 51 Three-axis robot 54 Surface plate

Claims (10)

A liquid discharge method in which a substrate for discharging liquid is placed on a surface plate, a dropping position of a needle is adjusted by a three-axis robot, a liquid having a viscosity of 10 cP or more is dropped from the needle, and the liquid is discharged onto the substrate. There,
The thickness of the needle tip [1/2 of (outer diameter−inner diameter)] is 0.05 mm to 0.20 mm,
The angle between the extension of the thick surface of the needle tip and the substrate surface is 0 ° to 20 °;
A liquid ejection method, wherein an inner diameter of the needle tip is 0.05 mm to 0.40 mm.   The liquid discharging method according to claim 1, wherein a plurality of liquids are discharged from the needle.   The liquid ejection method according to claim 2, wherein the liquid is dropped from the needle onto the substrate at substantially equal intervals.   The liquid ejection method according to claim 1, wherein the substrate is vacuum-sucked on a surface plate on the three-axis robot.   The liquid discharging method according to claim 1, wherein the surface plate is made of a porous ceramic.   The liquid discharging method according to claim 1, wherein the liquid is a liquid crystal. A needle for discharging a liquid having a viscosity of 10 cP or more;
A liquid storage container for storing the liquid;
A substrate to which the liquid is discharged;
A surface plate for holding the substrate;
In the liquid ejecting apparatus in which the needle is fixed by a three-axis robot,
A liquid having a viscosity of 10 cP or more is discharged from the tip of the needle to the substrate,
The thickness of the needle tip [1/2 of (outer diameter−inner diameter)] is 0.05 mm to 0.20 mm,
The angle between the extension of the thick surface of the needle tip and the substrate surface is 0 ° to 20 °;
A liquid ejection apparatus, wherein an inner diameter of the needle tip is 0.05 mm to 0.40 mm.   The liquid ejection apparatus according to claim 7, wherein the substrate is vacuum-sucked on a surface plate on the three-axis robot.   The liquid ejecting apparatus according to claim 7, wherein the surface plate is made of a porous ceramic.   The liquid ejecting apparatus according to claim 7, wherein the liquid is a liquid crystal.

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