JP2004223471A - Method and apparatus for coating application of liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for coating application of liquid which is capable of preventing adhesion of the liquid to a nozzle without using a specific means of removing a liquid pool. <P>SOLUTION: A prescribed amount of the liquid L is discharged to the tip of the discharge nozzle 2 in a position apart from an object W to form the liquid pool and the discharge nozzle 2 is lowered toward the object W. The discharge nozzle 2 is stopped in a position where the liquid L discharged from the discharge nozzle 2 adheres to the object W, and the contact angle θ between the liquid L and the outer peripheral surface of the discharge nozzle 2 attains ≥90°. The discharge nozzle 2 is thereafter pulled up, as a result of which the liquid L slips off from the discharge nozzle 2. The liquid L can thus be applied to the object W without allowing the liquid L to remain around the nozzle 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a liquid application method and apparatus suitable for applying a viscous liquid (or paste) such as a resin, an adhesive, or a silicone oil to an object in minute amounts.
[0002]
[Prior art]
[Patent Document 1] JP-A-5-329422 [Patent Document 2] JP-A-6-254664 Conventionally, a dispenser has been used as a device for accurately applying a predetermined amount of liquid such as a liquid resin or an adhesive to the surface of an electronic component or the like. There is known a liquid application device called a liquid application device.
In general, a dispenser is provided with a discharge nozzle at the lower end of a liquid container, and extrudes the liquid stored in the liquid container to apply the liquid to the surface of the object by a fixed amount from the discharge nozzle. However, a problem of the liquid coating apparatus is that, when continuous coating is performed, a liquid pool remains and increases on the outer peripheral portion of the nozzle, thereby deteriorating the coating accuracy. Therefore, maintenance for periodically removing the liquid pool from the nozzle is required, and there is a disadvantage that the working efficiency is reduced.
[0003]
In order to solve such a problem, liquid coating apparatuses as described in Patent Documents 1 and 2 have been proposed.
Patent Document 1 relates to an automatic adhesive application device, in which a pair of rotating rollers are arranged below a nozzle, a nozzle having an adhesive attached to the tip is driven downward, and the tip of the nozzle is inserted into a gap between the rollers. After insertion, the nozzle is pulled out to wipe off the adhesive adhered to the nozzle.
In the liquid application device of Patent Document 2, a nozzle receiver is attached to an outer periphery of a nozzle portion formed of a needle and a pipe, and air is supplied from the nozzle receiver to the space between the needle and the pipe through an oblique air passage. By blowing air downward from the gap between the peripheral surface and the outer peripheral surface of the needle, the liquid remaining at the tip of the nozzle portion is blown off.
[0004]
[Problems to be solved by the invention]
However, in the application device of Patent Document 1, the adhesive is wiped off by a pair of rotating rollers, and thus uneven wiping may occur. Further, since it is necessary to add an operation of inserting a nozzle between rollers during the application operation, the operation efficiency is not significantly improved.
Further, in the coating apparatus of Patent Document 2, since the liquid pool adhering to the tip of the discharge nozzle is blown off by air from a certain direction, a part of the torn liquid remains at the tip of the discharge nozzle, and the liquid pool is completely removed. Cannot be removed. For this reason, there has been a problem that not only the deterioration of the coating accuracy cannot be prevented, but also the liquid pool is blown off by air, so that the liquid scatters around and adheres to an object or the like.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for applying a liquid, which can prevent the liquid from adhering to the nozzles and use high accuracy of the application, without using a special liquid pool removing means.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a liquid application method for applying a liquid ejected from an ejection nozzle to an object, wherein a surface free energy E per unit area of an outer peripheral surface of the ejection nozzle is provided. Is larger than the surface tension γ of the liquid, a step of discharging a predetermined amount of liquid to the tip of the discharge nozzle at a position distant from the object to form a liquid pool, and the step of forming a liquid pool at the tip. The nozzle is lowered toward the target, and the discharge nozzle is stopped at a position where the liquid discharged from the discharge nozzle adheres to the target and the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 ° or more. And a step of applying a liquid to an object by raising the discharge nozzle.
[0007]
According to a second aspect of the present invention, there is provided a liquid applying method for applying a liquid ejected from an ejection nozzle to an object, wherein a surface free energy E per unit area of an outer peripheral surface of the ejection nozzle is equal to a surface tension of the liquid. a step of stopping the ejection nozzle at a position separated from the object by a predetermined distance in a case where the ejection liquid is ejected from the ejection nozzle by a predetermined amount. Stopping at a position where the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 ° or more, discharging the liquid from the discharge nozzle by the predetermined amount, and raising the discharge nozzle And a step of applying a liquid to an object.
[0008]
Further, the invention according to claim 3 is a liquid application apparatus for applying liquid discharged from a discharge nozzle to an object, wherein a surface free energy E per unit area of an outer peripheral surface of the discharge nozzle is equal to a surface tension of the liquid. a discharge nozzle driving means for driving the discharge nozzle in the vertical direction, a liquid discharge means for discharging a predetermined amount of liquid from the discharge nozzle, and a liquid discharged from the discharge nozzle adhering to an object. Coating position control means for controlling the distance between the object and the tip of the discharge nozzle so that the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 ° or more. The present invention provides a liquid application device that performs
[0009]
There is a relationship between the ejection nozzle and the liquid that is the object of the present invention that the surface free energy E per unit area of the outer peripheral surface of the ejection nozzle is larger than the surface tension γ of the liquid. That is, E> γ. Viscous liquids such as adhesives, resins, and silicone oils have surface tensions γ of several tens (mN / m), while the surface freedom per unit area of the discharge nozzle (treated on the metal surface) Since the energy E is about several hundreds (mN / m), the relationship of E> γ holds for a viscous liquid material.
When the liquid is water, the relationship of E <γ may be satisfied because the surface tension is large. In this case, since the liquid is naturally repelled by the discharge nozzle, the contact angle θ between the outer peripheral surface of the discharge nozzle and the liquid is always larger than 90 °. Therefore, even if the insertion depth (application position) of the discharge nozzle is not controlled, the discharge nozzle can be pulled up without the liquid remaining on the outer peripheral surface.
On the other hand, when E> γ, the liquid wets the surface of the discharge nozzle, so if the discharge nozzle is pulled up as it is, the liquid remains on the nozzle peripheral surface. The present inventor has discovered that even when E> γ, there is a position where the contact angle θ is 90 ° or more by controlling the position of the discharge nozzle. As a result, even when the liquid normally remains on the surface of the discharge nozzle, the discharge nozzle can be pulled up without the liquid remaining.
[0010]
FIG. 1 shows the movement when the discharge nozzle N having formed the liquid pool is lowered toward the object W and the liquid L is applied to the object W.
When the discharge nozzle N in which the liquid pool is formed is lowered toward the object W as shown in (a), the liquid L contacts the object W as shown in (b), and the liquid L spreads due to surface tension. It swells without roundness. When the discharge nozzle N is further lowered, a part of the discharge nozzle N is inserted into the liquid L as shown in FIG. The contact angle θ between the outer peripheral surface of the discharge nozzle N and the liquid increases with the insertion depth, and at the position (d), the contact angle θ is larger than 90 °. When the ejection nozzle N is further inserted, the contact angle θ becomes smaller than 90 ° as shown in (e), and the liquid L spreads around the ejection nozzle N.
As in (d), the contact angle θ stops the discharge nozzle N as it becomes larger than 90 °, increasing your discharge nozzle N from the position Z _0, without the liquid remaining on the outer peripheral surface, the discharge nozzle N can be raised. On the other hand, when the ejection nozzle N is pulled up from the positions Z ₁ and Z ₂ where the contact angle θ is smaller than 90 ° as in (c) and (e), the liquid remains on the outer peripheral surface of the ejection nozzle N.
[0011]
By raising the discharge nozzle from the position Z ₀ to the contact angle θ becomes larger than 90 ° as described above, it is possible to raise the discharge nozzle without the liquid remaining on the outer peripheral surface. Therefore, there is no liquid pool around the discharge nozzle at the time of next application, and high application accuracy can be maintained.
Further, since no device or maintenance for removing the liquid pool from the discharge nozzle is required, a low-cost coating method can be realized.
[0012]
The invention according to claim 2 is, as in claim 1, after forming a liquid pool at the tip of the discharge nozzle, instead of bringing the discharge nozzle close to the target, instead of bringing the discharge nozzle close to the target, The liquid is discharged from the discharge nozzle.
In this case, the discharge nozzle is stopped at a position separated from the target by a predetermined distance. The stop position is such that, when the liquid corresponding to one application amount is discharged from the discharge nozzle, the discharged liquid adheres to the object, and the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 °. This is the position described above. After stopping at the above position, when the liquid is discharged from the discharge nozzle by one application amount, the liquid adheres to the target and at the same time partially wraps around the discharge nozzle. Is 90 ° or more. When the discharge nozzle is pulled up from this state, the discharge nozzle can be pulled up without the liquid remaining on the outer peripheral surface.
[0013]
In the liquid application apparatus according to the third aspect, the application method according to the first or second aspect can be realized by the ejection nozzle driving unit, the liquid ejection unit, and the application position control unit.
As the discharge nozzle driving means, a combination of an electric motor and a ball screw, a linear driving device such as a fluid pressure cylinder and a voice coil motor can be used. The application position control means preferably detects the distance (displacement) between the tip of the discharge nozzle and the object, and performs feedback control of the discharge nozzle drive means based on the data.
In the above liquid applying apparatus, if the tip of the discharge nozzle is tapered as described in claim 4, the liquid can be discharged without strictly controlling the position of the discharge nozzle as compared with the case of a cylindrical shape. It is easy to set the contact angle θ with the outer peripheral surface of the nozzle to 90 ° or more.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 is an example of a liquid application device according to the present invention, and shows an example in which a viscous liquid L is applied to an object W.
The liquid application device includes a liquid container 1 called a syringe that stores a liquid L, and a discharge nozzle 2 is connected to a lower end thereof. A piston 3 is inserted into the liquid container 1 so as to be able to advance and retreat. The liquid container 1 is held by a holder 4, and the holder 4 is attached to an arm unit 5 such as a robot via a discharge nozzle driving unit 6. The discharge nozzle driving means 6 of this embodiment is guided by a guide 7 for vertically moving the holder 4 with respect to the arm 5, a servomotor 8 fixed to the arm 5, and rotationally driven by the servomotor 8. A ball screw 9 is provided, and a part 4 a of the holder 4 is screwed to the ball screw 9. Therefore, when the servo motor 8 is driven, the holder 4 can move smoothly in the vertical direction by the action of the ball screw 9 and the guide 7. That is, the position (application position) of the discharge nozzle 2 can be controlled with high accuracy.
[0015]
The surface of the discharge nozzle 2 is subjected to a water-repellent coding process in order to reduce the surface free energy E as much as possible. The liquid L is made of a material having a relatively small surface tension γ, such as silicone oil. The following relationship is established between the surface energy E of the discharge nozzle 2 and the surface tension γ of the liquid.
E> γ
[0016]
The piston 3 is driven by a constant amount by a piston driving means 10. The piston driving means 10 of this embodiment includes a stepping motor 11 fixed to the upper end of the holder 4, a ball screw 12 rotationally driven by the stepping motor 11, a nut member 13 fixed to the upper end of the piston 3, And a guide 14 for guiding the nut member 13 in the vertical direction. The nut member 13 is screwed to the ball screw 12. Therefore, when the stepping motor 11 is driven, the piston 3 is driven vertically, and the liquid L can be discharged by a constant amount.
[0017]
The application position of the discharge nozzle 2 is controlled to a position where the liquid L discharged from the discharge nozzle 2 adheres to the target object W and the contact angle θ between the liquid L and the outer peripheral surface of the discharge nozzle 2 is 90 ° or more. Application position control means 15 is provided. Here, the application position control means 15 is fixed to the arm section 5 via the retainer 16 and discharges a displacement meter 17 such as a laser displacement meter for detecting the tip position of the discharge nozzle 2 and discharges the detection data of the displacement meter 17. And a controller 18 for feeding back to the nozzle driving means 6. The controller 18 also controls the piston driving means 10. The application position control means 15 can also be configured by a camera that captures an image of the tip of the discharge nozzle 2 and an image processing circuit that controls the application position of the discharge nozzle 2 by image processing from the captured data. Since the position of the discharge nozzle 2 can be detected by the rotation amount of the servo motor 8, the displacement gauge 17 for detecting the position of the tip of the discharge nozzle 2 can be omitted.
[0018]
Here, an operation of applying a fixed amount of the liquid L to the object W using the liquid applying apparatus will be described with reference to FIG.
First, the robot is operated in the X and Y directions to position the discharge nozzle 2 directly above the target object W. Here, the piston 3 is actuated by the piston driving means 10 to discharge the liquid L corresponding to one application amount to the tip of the discharge nozzle 2 to generate a liquid pool (see FIG. 3A).
Next, the discharge nozzle driving means 6 is driven to lower the discharge nozzle 2 to the application position Z (see FIG. 3B). Here, the application position Z is a position where the liquid L discharged from the discharge nozzle 2 adheres to the target object W and the contact angle θ between the liquid L and the outer peripheral surface of the discharge nozzle 2 is 90 ° or more.
Thereafter, the discharge nozzle 2 is pulled up by the discharge nozzle driving means 6. Since the contact angle θ between the outer peripheral surface of the discharge nozzle 2 and the liquid L is 90 ° or more, the discharge nozzle 2 is pulled up, so that the liquid L slides down along the peripheral surface of the discharge nozzle 2 and No liquid L remains. Further, regardless of the pulling speed of the discharge nozzle 2, the residual liquid L can be eliminated.
[0019]
The inventor applied the liquid L to the object W under the following conditions.
Discharge nozzle: Nozzle diameter: φ0.3 mm, surface coated with fluorine coating, material: SUS304 nozzle liquid: Silicon oil (viscosity: 10 Pa · s, surface tension: 20 mN / m)
Target: After discharging 10 μg of silicon oil from the tip of the fluorine-coated discharge nozzle 2 on the upper surface, the discharge nozzle 2 was positioned at a position where the distance Z between the discharge nozzle 2 and the target W was 50 μm. At this time, the contact angle θ could be set to 90 ° or more (θ ≒ 110 °). Here, when the discharge nozzle 2 is raised after waiting for a predetermined time (50 ms), a predetermined amount of the liquid L is accurately applied to the target object W without generating a liquid pool on the peripheral surface of the discharge nozzle 2. We were able to.
[0020]
FIG. 4 shows a second embodiment of the present invention.
In the first embodiment, after forming the liquid pool at the tip of the discharge nozzle 2, the discharge nozzle 2 is moved closer to the target object W. In the second embodiment, after the discharge nozzle 2 is moved closer to the target object W, The liquid L is discharged from the discharge nozzle 2. Also in this case, the relationship of E> γ is established between the surface energy E of the discharge nozzle 2 and the surface tension γ of the liquid.
[0021]
FIG. 4A shows a state in which the discharge nozzle 2 is lowered without discharging the liquid L, and the discharge nozzle 2 is stopped at a position separated by a predetermined distance Z from the object W. In this position, when a predetermined amount of liquid L is discharged from the discharge nozzle 2, the discharged liquid adheres to the target object W, and at the same time, the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle 2 becomes 90 ° or more. Position.
Next, as shown in FIG. 4B, the liquid L is discharged from the discharge nozzle 2 by a predetermined amount while maintaining the distance Z between the discharge nozzle 2 and the object W. At this time, the liquid L adheres to the target object W, and at the same time, a part of the liquid L wraps around the outer peripheral side of the discharge nozzle 2, and the contact angle θ between the liquid L and the outer peripheral surface of the discharge nozzle 2 becomes 90 ° or more.
Next, when the discharge nozzle 2 is pulled up, the liquid L slides down from the outer peripheral surface of the discharge nozzle 2 as shown in FIG. It can be applied to the object W.
In the case of this embodiment, there is no need to form a liquid pool at the tip of the discharge nozzle 2 before application as shown in FIG. 3A, so that when the amount of application is large, the liquid L There is a feature that it can be prevented from accidentally falling on W.
[0022]
FIG. 5 shows another embodiment of the discharge nozzle 2.
In this embodiment, the tip 2a of the discharge nozzle 2 has a tapered shape. In this case, since the outer peripheral surface of the discharge nozzle 2 is inclined downward, it is easy to set the contact angle θ between the liquid L and the outer peripheral surface of the discharge nozzle 2 to 90 ° or more. Therefore, as compared with a cylindrical nozzle, variation in the application position Z can be absorbed, and application position control becomes easier.
[0023]
In the above embodiment, the example in which the ejection nozzle is driven up and down with respect to the object is described. However, the same operation and effect can be obtained even if the ejection nozzle is held at a fixed position and the object is driven up and down with respect to the ejection nozzle. Having.
The liquid used in the present invention is not limited to liquid at room temperature, such as silicone oil, conductive paste, sealing resin, cream solder, and ceramic slurry, and is solid at room temperature, but becomes liquid when heated. (For example, wax).
[0024]
【The invention's effect】
As is clear from the above description, according to the invention according to claim 1, after a predetermined amount of liquid is discharged to the tip of the discharge nozzle to form a liquid pool, the liquid discharged from the discharge nozzle is applied to the target object. The discharge nozzle is lowered to a position where the contact angle θ between the liquid and the liquid and the outer peripheral surface of the discharge nozzle becomes larger than 90 °, and then the discharge nozzle is lifted up. The liquid can be prevented from sliding down from the nozzle and remaining on the outer peripheral surface of the discharge nozzle. Therefore, it is possible to prevent a decrease in coating accuracy due to an increase in liquid pool in continuous coating, which is a general problem of the liquid coating apparatus, and to maintain a high coating accuracy.
Further, it is not necessary to perform maintenance of the discharge nozzle for removing the liquid pool such as wiping of the discharge nozzle and air blowing.
Further, in the present invention, since the liquid does not adhere around the nozzle, it is possible to prevent the liquid from scattering around when removing the liquid pool.
[0025]
According to the second aspect of the invention, when a predetermined amount of liquid is discharged from the discharge nozzle, the discharged liquid adheres to the target, and the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 °. The discharge nozzle is stopped at the position described above, and after discharging the liquid from the discharge nozzle by a predetermined amount, the discharge nozzle is lifted, so that the liquid remains on the outer peripheral surface of the discharge nozzle as in claim 1. This is advantageous in that high precision of application can be maintained, and no liquid pool removing device or maintenance is required.
[0026]
According to the third aspect of the invention, the application method according to the first or second aspect can be easily realized by the ejection nozzle driving unit, the liquid ejection unit, and the application position control unit.
[Brief description of the drawings]
FIG. 1 is a diagram showing an operation of applying a liquid to an object by a discharge nozzle.
FIG. 2 is a configuration diagram of an example of a liquid application device according to the present invention.
FIG. 3 is an operation diagram of a first embodiment of the liquid applying method according to the present invention.
FIG. 4 is an operation diagram of a second embodiment of the liquid applying method according to the present invention.
FIG. 5 is a view of another embodiment of a discharge nozzle according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid container 2 Discharge nozzle 3 Piston 6 Discharge nozzle drive means 10 Piston drive means 15 Application position control means 18 Controller L Liquid W Object

Claims (4)

A liquid application method for applying a liquid discharged from a discharge nozzle to an object, wherein a surface free energy E per unit area of an outer peripheral surface of the discharge nozzle is larger than a surface tension γ of the liquid,
A step of discharging a predetermined amount of liquid to the tip of the discharge nozzle to form a liquid pool at a position away from the object,
The discharge nozzle having the liquid reservoir formed at the tip is lowered toward the object, the liquid discharged from the discharge nozzle adheres to the object, and the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 ° or more. Stopping the discharge nozzle at a position where
A step of applying a liquid to an object by raising the discharge nozzle. A liquid application method for applying a liquid discharged from a discharge nozzle to an object, wherein a surface free energy E per unit area of an outer peripheral surface of the discharge nozzle is larger than a surface tension γ of the liquid,
A step of stopping the ejection nozzle at a position separated by a predetermined distance from the object, wherein when the ejection nozzle ejects a predetermined amount of liquid, the ejected liquid adheres to the object, and Stopping at a position where the contact angle θ between the discharge nozzle and the outer peripheral surface of the discharge nozzle is 90 ° or more;
Discharging the liquid from the discharge nozzle by the predetermined amount,
A step of applying a liquid to an object by raising the discharge nozzle. In a liquid coating apparatus for applying liquid discharged from a discharge nozzle to an object, a surface free energy E per unit area of an outer peripheral surface of the discharge nozzle is larger than a surface tension γ of the liquid,
Discharge nozzle driving means for driving the discharge nozzle in the vertical direction;
Liquid ejection means for ejecting a predetermined amount of liquid from the ejection nozzle,
The distance between the target and the tip of the discharge nozzle is controlled so that the liquid discharged from the discharge nozzle adheres to the target and the contact angle θ between the liquid and the outer peripheral surface of the discharge nozzle is 90 ° or more. And a coating position control unit. The liquid application device according to claim 3, wherein a tip portion of the discharge nozzle has a tapered shape.

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