HK1228836B - Droplet discharge device and method - Google Patents

Description

Liquid droplet discharging device and method

This application is a divisional application of a patent application filed on July 10, 2012 , with application number 201280034714.3 and invention name: Liquid Droplet Discharging Device and Method.

Technical Field

The present invention relates to a liquid droplet discharging device and method for accurately discharging a small amount of liquid material ranging from low-viscosity materials such as water, solvents, and reagents to high-viscosity materials such as solder paste, silver paste, and adhesives, regardless of the filler content.

Background Art

Various techniques have been proposed so far as a liquid droplet discharge device that uses a reciprocating plunger to discharge a small amount of liquid material from a discharge port.

As a type of droplet ejection device that causes the front end of a plunger to contact a valve seat to eject liquid, for example, Patent Document 1 discloses a droplet ejection device that causes a liquid material to land on a workpiece after leaving a nozzle. The side surface of the plunger is non-contactly arranged in a flow path having a valve seat near an outlet connected to the nozzle, and the front end of the plunger moves toward the valve seat and abuts the valve seat, thereby ejecting liquid material from the nozzle in the form of droplets.

However, when the plunger contacts the valve seat, there are problems such as the plunger being worn and deformed, and wear powder and flakes being generated, which contaminate the liquid material or become caught between the plunger and the valve seat and prevent good discharge.

Therefore, as a droplet ejection device that ejects liquid without the front end of the plunger contacting the valve seat, the applicant proposed a droplet ejection device that imparts inertial force to the liquid material by moving the plunger in and out and stopping the plunger in and out, and ejects the liquid material in the form of droplets. The device has a plunger positioning mechanism that defines the position of the front end of the plunger when the plunger stops moving in and out near the inner wall of the liquid chamber in its in and out direction (patent document 2).

In addition, Patent Document 3 discloses a device that is configured to discharge droplets of fluid of material from a nozzle opening by propagating a pressure wave formed by a driving device causing the rod end face to displace back and forth within a chamber with an extremely small stroke, high acceleration, and large force within the chamber, thereby propagating the pressure wave within the material in the chamber.

However, in recent years, as electronic devices are being miniaturized and lightweighted, the electronic components mounted thereon have been miniaturized and lightweighted. For example, since around 2005, components with a mounting size of 400μm×200μm, called "0402 components," have been installed, which can significantly reduce the mounting area. 0402 components are currently mounted by solder printing on metal plates, but there is a problem that half-etching and other labor are required when mixed with large components. In addition, there is also the problem of requiring individual control of the coating amount (coating thickness). Therefore, the yield rate of mounting using printing deteriorates. In addition, in order to ensure printability, there are sometimes restrictions on component configuration.

Droplet dispensing devices using a reciprocating plunger avoid these problems because the liquid material can be controlled by the plunger's movement. However, until now, such devices have not been able to accurately dispense droplets of liquids such as solder paste required for small components, without the plunger contacting the valve seat.

Prior art literature

Patent Literature

Patent Document 1: International Publication No. 98/10251 Pamphlet

Patent Document 2: International Publication No. 2008/108097 Pamphlet

Patent Document 3: International Publication No. 98/16323 Pamphlet

Summary of the Invention

Problems to be solved by the invention

An object of the present invention is to discharge a minute amount of liquid droplets with high precision in a liquid droplet discharge device using a reciprocating plunger without the plunger coming into contact with an inner wall (valve seat) of a liquid chamber.

Furthermore, the present invention is also intended to solve the problem of discharging various liquids ranging from low viscosity to high viscosity in the same liquid droplet discharge device.

Technical means to solve the problem

The first invention is a liquid droplet discharge device, characterized in that it includes a discharge path with a discharge port formed at its front end, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for determining the position of the front end of the plunger. By moving the plunger forward while the front end of the plunger is not in contact with the inner wall of the liquid chamber, an inertial force is imparted to the liquid material, causing it to be discharged in the form of droplets. By moving the plunger forward, the liquid material required to form the desired droplets is extruded from the discharge port. Subsequently, by moving the plunger backward, the liquid material extruded from the discharge port is cut off and a small amount of droplets are formed.

The second invention is characterized in that, in the first invention, the discharge path is composed of a first flow path having a distal end forming a discharge port, and a second flow path communicating with the first flow path and the liquid chamber and having a larger diameter than the first flow path.

The third invention is characterized in that, in the second invention, after the liquid material extruded from the discharge port is cut off by moving the plunger backward, the plunger is further moved backward to form a gas-liquid interface in the first flow path or the second flow path of the discharge path, thereby stopping the movement of the plunger.

The fourth invention is characterized in that, in the first invention, after the liquid material extruded from the discharge port is cut off by the backward movement of the plunger, the plunger is further backward moved to form a gas-liquid interface in the discharge path, and the movement of the plunger is stopped.

The fifth invention is characterized in that, in the third or fourth invention, a gas-liquid interface is formed in the discharge path, the plunger is moved forward from the position of the plunger when it stops moving, thereby squeezing out the liquid material in the amount required to form the desired droplets from the discharge port, and then the plunger is moved backward to cut off the liquid material squeezed out from the discharge port and continuously form a small amount of droplets.

The sixth invention is characterized in that, in any one of the first to fifth inventions, the inner diameter of the discharge port is several tens of μm or less.

The seventh invention is a liquid droplet discharge method, characterized in that it is a liquid droplet discharge method using a liquid droplet discharge device, in which the plunger is moved forward while the front end of the plunger is not in contact with the inner wall of the liquid chamber, thereby imparting inertial force to the liquid material and discharging it in the form of droplets. The liquid droplet discharge device includes a discharge path with a front end constituting a discharge port, a plunger, a liquid chamber in which the plunger is inserted, a plunger driving mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for determining the position of the front end of the plunger. The liquid droplet discharge method includes: an extrusion step of moving the plunger forward to extrude a required amount of liquid material from the discharge port to form desired droplets; and a cutting step of moving the plunger backward to cut the liquid material extruded from the discharge port and form a small amount of droplets.

The eighth invention is characterized in that, in the seventh invention, after the cutting step, there is further provided a suction step of moving the plunger backward to form a gas-liquid interface in the discharge path and stopping the movement of the plunger.

The ninth invention is characterized in that, in the seventh or eighth invention, the liquid material is a liquid material containing a solid substance, and the distance between the tip of the plunger and the inner wall of the liquid chamber in the extrusion step is set to be larger than the solid substance.

The tenth invention is characterized in that, in any one of the seventh to ninth inventions, the inner diameter of the discharge port is several tens of μm or less.

The eleventh invention is characterized in that, in any one of the seventh to tenth inventions, the viscosity of the liquid material is 10,000 mPa·s or more.

The twelfth invention is characterized in that, in any one of the seventh to eleventh inventions, the distance the plunger moves forward during the extrusion step is greater than the distance between the tip of the plunger and the inner wall of the liquid chamber immediately after the step. Here, the distance the plunger moves forward during the extrusion step is preferably at least three times the distance between the tip of the plunger and the inner wall of the liquid chamber immediately after the step, more preferably at least six times, and particularly preferably at least ten times.

Effects of the Invention

According to the present invention, it is possible to discharge a minute amount of liquid droplets with high precision, which has been impossible to discharge without causing the plunger (valve body) to abut against the inner wall of the liquid chamber (valve seat).

In addition, since the valve body and valve seat do not contact each other, there is no friction or particles generated, and there is no worry of them mixing into the material, allowing for pollution-free micro-dispensing.

Furthermore, even when the liquid material contains a solid substance such as a filler, a decrease in discharge accuracy due to crushing or breaking of the solid substance can be prevented, and the liquid material can be discharged without losing its functions and properties.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side sectional view of the main part of the droplet ejection device for illustrating the relationship between the position of the plunger and the state of the liquid material, (a) shows the first stage, (b) shows the second stage, (c) shows the third stage, (d) shows the fourth stage, (e) shows the fifth stage, (f) shows the sixth stage, (g) shows the seventh stage, and (h) shows the eighth stage.

Figure 2 shows examples of deformation of the shape of the plunger and the discharge path, (a) shows the first example, (b) shows the second example, (c) shows the third example, (d) shows the fourth example, (e) shows the fifth example, (f) shows the sixth example, (g) shows the seventh example, and (h) shows the eighth example.

3 is a side sectional view of a liquid droplet discharge device equipped with a plunger positioning mechanism, (a) showing a state where a moving member is advanced and extended, and (b) showing a state where the moving member is retracted.

DETAILED DESCRIPTION

The present invention relates to a technique for discharging a liquid material from a discharge port formed at the distal end of a discharge path in the plunger's forward and backward directions by the forward and backward movement of a plunger inserted into an insertion hole communicating with a liquid chamber, with the distal end moving forward and backward without contacting the inner wall of the liquid chamber. The technique of the present invention enables precise and minute discharge of liquid materials, ranging from low-viscosity to high-viscosity, in the form of droplets from the discharge port, regardless of the filler content.

According to the present invention, liquid materials ranging from low-viscosity materials such as water, solvents, and reagents to high-viscosity materials such as solder paste, silver paste, and adhesives can be discharged in minute amounts. The present invention has the characteristic of being applicable to high-viscosity liquid materials that are not suitable for discharge in inkjet printing, such as solder paste (creamsolder). Here, the so-called high-viscosity liquid material refers to, for example, a liquid with a viscosity of 10,000 to 500,000 mPa·s. In particular, it has been impossible to discharge a liquid with a viscosity of 20,000 to 500,000 mPa·s in a minute amount in the form of drops without the plunger (valve body) abutting against the inner wall (valve seat) of the liquid chamber, and further, a liquid with a viscosity of 30,000 to 500,000 mPa·s, in the form of drops, at the current industrial level.

Micro-discharge in the present invention refers to the discharge of droplets with landing diameters of tens to hundreds of μm, or droplets with a volume of 1 nl or less (preferably 0.1 to 0.5 nl or less). The present invention is characterized by the ability to form droplets even with a discharge orifice diameter of tens of μm or less (preferably 30 μm or less).

Hereinafter, an example of a mode for implementing the present invention will be described with reference to FIG. 1 .

Fig. 1 is a cross-sectional view of a main portion of a liquid droplet discharge device (dispenser). First, the structure of the main portion (discharge portion) of the liquid droplet discharge device will be described.

The discharge portion shown in FIG. 1 includes a plunger 30 , a liquid chamber 50 , an insertion hole 51 , a liquid supply path 52 , and a discharge path 12 .

The liquid chamber 50 is a space filled with a liquid material and where the plunger tip 31 is located. The liquid chamber 50 shown in FIG1 has a top surface, side surfaces, and a bottom surface and is formed in a cylindrical shape.

An insertion hole 51 is provided on the upper surface of the liquid chamber 50. The plunger 30 is inserted into the insertion hole 51, and the front end of the plunger 30 is located in the liquid chamber 50. The width (diameter) of the liquid chamber 50 is wider than the width (diameter) of the plunger 30, and the outer periphery of the plunger 30 is always in a non-contact state with the side surface of the liquid chamber 50. The plunger 30 is connected to a plunger drive mechanism not shown in the figure, and moves forward in a straight line in a manner of approaching or moving away from the discharge path 12. In Figure 1, the shape of the front end portion 31 is shown as a plane, but it is not limited to this. For example, it can also be spherical, or concave, or have a tapered front end, or a protrusion can be provided at a position opposite to the discharge path 12. Figures 2(a) to (g) show examples of the shape of the front end portion 31 of the plunger.

A liquid supply path 52 is provided on a side surface of the liquid chamber 50 . The liquid material is supplied to the liquid chamber 50 through the liquid supply path 52 from a liquid material supply portion such as a liquid material storage container (not shown).

A discharge path 12 connected to the outside is provided on the bottom surface of the liquid chamber 50. The liquid material is discharged to the outside from the discharge port 11 at the front end of the discharge path 12 by the in-and-out movement of the plunger. The inner diameter of the discharge port 11 is, for example, 10 to 100 μm. The shape of the discharge path 12 is not limited to a cylindrical shape, and may also be a tapered shape with a tapered front end (refer to FIG. 2 (e) and (g)). In addition, it may also be composed of a first flow path 21 having a discharge port and a second flow path 22 having a diameter larger than that of the first flow path (refer to FIG. 2 (f)). In this case, the second flow path 22 may also be formed into a truncated cone shape (refer to FIG. 2 (a) to (d)). When the diameter of the liquid chamber side is made larger than that of the discharge port side of the discharge path, the effect of accelerating the liquid material flowing into the discharge path is achieved.

When the length of the discharge path is too long, the droplets cannot be cut off well, and this problem is likely to occur in liquid materials with high viscosity. Therefore, it is preferred that the discharge path 12 is formed by an orifice (orifice) in which a hole is set on the wall 53 in the liquid chamber. The length of the discharge path is, for example, 100 μm to 1000 μm. In addition, a depression having a diameter larger than that of the plunger 30 can be provided on the wall 53 in the liquid chamber, and a surface opposite to the front end 31 of the plunger can be formed at a position closer to the discharge port. In this case, the surface in the depression opposite to the front end 31 of the plunger to the discharge port 11 becomes the discharge path 12 (refer to FIG. 2 (f)). In addition, the wall 53 can also be made into a thin-walled curved surface as the central part where the discharge path 12 is located (refer to FIG. 2 (g)).

As the plunger drive mechanism, an elastic body such as a motor, a piezoelectric element, a spring, or an actuator using air pressure can be exemplified. The plunger drive mechanism can adopt an appropriate mechanism according to the application. However, when it is desired to discharge a variety of liquids ranging from low viscosity to high viscosity, it is preferable to use a mechanism (a drive mechanism other than a piezoelectric element) that can adjust the plunger stroke within a certain range. The plunger stroke when performing a micro-discharge is, for example, 5 to 1000 μm. However, it is preferable to extend the stroke to, for example, 50 to 1000 μm when discharging a high-viscosity liquid.

The position of the plunger's tip at the most advanced position is determined by the plunger positioning mechanism. To impart sufficient inertial force to the liquid material in the plunger's advanced and indirect directions, the distance between the plunger's end face and the liquid chamber wall 53 facing the plunger's tip 31 is preferably set to be sufficiently narrow. As the inner diameter of the discharge path (nozzle) decreases, the force imparted by the plunger to the liquid material must increase. Consequently, the distance (gap) between the plunger's end face and the liquid chamber wall must also decrease.

For example, in order to form droplets with a landing diameter of less than 300 μm from a high-viscosity liquid, the gap is preferably set in the range of 1 to 50 μm, and more preferably in the range of 1 to 30 μm. However, in the case where the liquid material contains solid substances such as fillers, the maximum entry and exit positions are set so that the gap is larger than the solid substance. For example, in the case where the liquid material is a solder paste with particles with an average particle size of 10 μm, the gap needs to be larger than 10 μm (preferably the gap is 1.5 times the size (particle size) of the solid substance). This is because there will be a problem that the solder particles are crushed and stacked near the inlet of the discharge path, which significantly reduces the discharge accuracy.

The plunger positioning mechanism also specifies the position of the front end of the plunger in the most retracted position. The reason is that when discharging a low-viscosity liquid material, if the plunger is moved at a certain speed, the inertial force required to form a droplet can be imparted. However, when discharging a high-viscosity liquid material, in order to move the plunger at a higher speed, the stroke needs to be set to be longer. Generally speaking, when discharging a small amount of a high-viscosity liquid (for example, a liquid with a viscosity of 10,000 mPa·s or more), the stroke needs to be set to be sufficiently larger than the gap. The stroke of the plunger is preferably more than 3 times the gap at its most in-and-out position, more preferably more than 6 times, and particularly preferably more than 10 times.

An example of the plunger positioning mechanism will be described with reference to Fig. 3. The plunger positioning mechanism described here is disclosed in Patent Document 2.

The plunger's most advanced and exited positions are determined in the following order.

First, the electromagnetic switching valve 72 is switched to a state where the front piston chamber 43 is in communication with the outside, and the movable member 40 is rotated, moving the movable member 40 to its forwardmost position. Since the front piston chamber 43 is open to the outside, the piston 33 is moved forward relative to the main body 71 by the action of the coil spring 45, and the front abutment portion 32 abuts the front stopper 41, stopping. Next, the micrometer 69 is rotated, and the rear stopper 42 is advanced until it contacts the rear abutment portion 34, thereby securing the plunger 30 and the main body 71.

The main body 71 is moved forward and fixed with the rear stopper 42 in contact with the rear abutment portion 34. The front end portion 31 of the plunger 30 is fixed at the contact position 13 where it contacts the inner wall of the liquid chamber 50. The moving member 40 is rotated, and only the moving member 40 is moved rearward to define the maximum forward and backward position, and the drive unit 70 is fixed to the base member 73.

By the above operation, the stop position of the plunger 30 during the in-and-out movement can be adjusted to a desired position where the tip portion 31 of the plunger 30 does not contact the liquid chamber 50 .

The final retracted position of the plunger is determined in the following procedure.

The micrometer 46 is rotated to retract the rear stopper 42, thereby determining the amount of retraction of the plunger 30 during dispensing. Once the amount of retraction of the plunger 30 has been determined, the micrometer 46 is secured with a rotation locking member, such as a setscrew (not shown), to prevent rotation. This completes the process of setting the plunger 30's fully retracted position.

The droplet discharge device of the present invention is typically used to discharge liquid material while moving a workpiece and a discharge port relative to each other. The droplet discharge device is attached to an XYZ drive mechanism and moves relative to a worktable on which the workpiece is mounted. In the present invention, since the liquid forms droplets, separates from the discharge port, and lands on the workpiece, the discharge port can be maintained at a constant height while being moved horizontally.

If a single droplet is discharged from a single working location, it may be possible to ensure the desired volume by discharging multiple drops into the same location. Increasing the volume per shot widens the landing diameter, so if a wider landing diameter is undesirable, it is preferable to ensure the desired volume with multiple shots. The droplet discharge device of the present invention is capable of discharging minute amounts of liquid continuously and at high speeds, for example, operating at a high rate of over 100 shots per second.

Next, the relationship between the position of the plunger and the state of the liquid material will be described.

Figure 1(a) shows the initial state at the start of the dispensing operation. In this initial state, the tip 31 of the plunger 30 is at its starting position, farthest from the dispensing passage 12 during the series of dispensing operations. Furthermore, the liquid chamber 50 and the dispensing passage 12 are filled with liquid material. At this point, the discharge port 11 side of the dispensing passage 12 may also be drawing in a small amount of external air.

FIG1(b) shows a state where the plunger is moved forward from the plunger operation start position of FIG1(a) and the liquid material in the discharge path 12 reaches the discharge port (the discharge port side end surface of the discharge path 12).

At this time, the plunger 30 moves forward, and the liquid material in the liquid chamber 50 is sent into the discharge path 12. The liquid material in the discharge path 12 reaches the discharge port 11 at the front end of the discharge path 12. As a result, the external air (air) in the discharge path 12 is discharged to the outside.

Fig. 1(c) shows a state where the plunger is further moved forward from the position of the plunger in Fig. 1(b). In this state, the liquid material reaching the discharge port is not cut off and is squeezed out of the discharge port.

FIG1(d) shows a state in which the plunger is further advanced from the position of the plunger in FIG1(c) and then the forward movement of the plunger is stopped.

At this time, the liquid material is not cut off between the liquid chamber 50 and the front end, but is further squeezed outward from the discharge port 11 which is the front end of the discharge path 12 .

It is preferable that the forward movement of the plunger 30 up to this point is performed strongly, and the stop of the plunger 30 is performed abruptly.

In this state, the tip 31 of the plunger 30 is at its most advanced position relative to the discharge path 12 during a series of discharge operations. As the plunger 30 moves to its most advanced position, the amount of liquid material required to form droplets of the desired size is extruded outward from the discharge port 11. The most advanced position varies depending on the type of liquid material and the size of the droplets to be formed, but in either case, the tip 31 of the plunger 30 does not contact the interior of the liquid chamber.

FIG1(e) shows a state where the plunger is slightly moved backward from the position of the plunger in FIG1(d) (the most advanced position).

If the plunger 30 moves backward, the proportion of the plunger's volume within the liquid chamber 50 that it occupies decreases, and a force pulling the liquid material toward the liquid chamber 50 acts on the liquid material within the discharge path 12. This force also acts on the liquid material outside the discharge port 11 (the extruded liquid material connected to the liquid material within the discharge port 12) pulling the liquid material back toward the discharge port 12. Therefore, the inertial force acting in the forward direction of the plunger and the force acting in the backward direction of the plunger act on the liquid material extruded from the discharge port, causing droplets to begin to form. In other words, the liquid material extruded from the discharge port 11 connected to the liquid material within the discharge port 12 is sheared off near the discharge port.

FIG1(f) shows a state where the plunger is further moved backward from the position of the plunger in FIG1(e).

If the plunger 30 is further moved backward, the cutting effect on the liquid material extruded from the discharge port 11 is further strengthened. As a result, the liquid material extruded from the discharge port 11 continuous with the discharge path 12 is cut near the discharge port, forming droplets.

In FIG1(f), both the area near the cutoff point of the liquid material on the side continuing from the discharge path 12 and the area near the cutoff point of the liquid material on the side being cut are depicted as filaments. Generally speaking, high-viscosity materials often form such filaments, but this may not necessarily be the case with high-viscosity materials, depending on the material properties and environmental conditions such as temperature and humidity.

1( g ) shows a state where the plunger is further moved backward from the position of the plunger in FIG1( f ). The liquid material remaining on the discharge path 12 side of the liquid material extruded from the discharge port 11 is sucked into the discharge path 12 by the backward movement of the plunger 30 .

In the next discharge, the discharge port 11 side of the discharge path 12 is preferably configured to be in a state where a small amount of external air (air) is sucked in. That is, it is preferred that a gas-liquid interface exists in the discharge path 12. By doing so, it is possible to prevent the liquid material from drying out, and it is also possible to prevent the surrounding environment from being polluted by dripping during the discharge operation standby. Here, it should be noted that external air (air) is not sucked into the liquid chamber 50 across the discharge path 12. The reason is that if external air (air) is sucked into the liquid chamber 50, it will have an adverse effect on the discharge accuracy.

Furthermore, when the discharge passage 12 is formed by having the first flow passage 21 and the second flow passage 22, the gas-liquid interface may exist in either the first flow passage 21, the second flow passage 22, or the boundary therebetween, even if the boundary therebetween does not form a step (e.g., in the case of the flow passage shapes shown in FIG. 2(a) and (b)). Furthermore, as shown in FIG. 2(f), even if the boundary therebetween forms a step, external air (air) can be drawn into the second flow passage 22 if no bubbles are formed. Alternatively, the boundary between the cylindrical first flow passage 21 and the cylindrical second flow passage 22 may be smoothly connected by a taper.

Figure 1(h) shows a state where the plunger is further moved backward from the position of the plunger in Figure 1(g) and becomes the end position of the action. Figures 1(a) to (h) are a series of actions for forming a drop. The position of the plunger when one discharge is completed becomes a position further back than the most in-and-out position. In this state, a small amount of external air (air) is sucked into the discharge port 11 side of the discharge path 12. Even if external air (air) is sucked into the discharge path 12, there will be no problem of bubbles as long as the air does not reach the liquid chamber 50. Since if external air flows into the liquid chamber 50, it will cause deviations in the discharge amount, etc., it is necessary to avoid this. In order to continuously perform the next discharge action, it is preferable to use the end position of the plunger as the start position of the action.

When the discharge operation is completely completed, the discharge path 12 is preferably blocked by the distal end portion 31 of the plunger 30 to prevent the liquid material from flowing out of the discharge port 11 .

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the examples at all.

Example 1

Droplets were formed using the droplet ejection device shown in Figure 1. The liquid material used in Example 1 was solder paste (viscosity 45,000 mPa·s) containing filler with an average particle size of 6 μm. The volume of each ejected droplet in this example was 0.2 nl, and the landing diameter was 120 μm. While the workpiece and the ejection port were moving relative to each other, dozens of droplets were deposited on the workpiece at a rate of 100 drops per second. Measurements with a measuring instrument confirmed the formation of uniformly shaped dots.

Example 2

The droplet ejection device shown in Figure 1 is used to form droplets. The liquid material used in Example 2 is an Ag paste (viscosity 28000mPa·s) containing a frame-shaped filler of 1 to 10μm. The amount of one droplet ejected in this example is 0.17nl, and the landing diameter is 100μm. While the workpiece and the ejection port are relatively moved, dozens of droplets are formed on the workpiece at a rate of 250 injections per second. After measurement by a measuring instrument, it can be confirmed that points with uniform shapes are formed.

Industrial applicability

According to the present invention, it is possible to precisely and minutely discharge materials that are difficult to obtain in the electronics and semiconductor markets without the plunger (valve body) contacting the inner wall (valve seat) of the liquid chamber. For example, paste materials containing soft metal materials such as solder paste can be discharged continuously without causing clogging within the dispensing device. The present invention has a wide range of applications, including processes for mounting small components on substrates and manufacturing solar cells.

In addition, since the valve body and the valve seat do not contact each other, no friction plates or particles are generated, and there is no worry about them mixing into the material (i.e., no pollution). Therefore, it is also suitable for use in the food or pharmaceutical industries.

In addition, since the structure is not destroyed unnecessarily to cause particles of fillers, solid materials, gels, structures, etc. to fly and be discharged, clogging of the nozzle caused by these destructive objects can be effectively prevented.

Explanation of symbols

11 Spit

12 Spit Road

13 Contact position

21 1st flow path

22 2nd flow path

30 plunger

31 front end

32 front contact portion

33 Piston

34 rear contact portion

40 Moving Components

41 Front stopper

42 rear stopper

43 front piston chamber

44 Rear piston chamber

45 coil spring

46 Micrometer

50 liquid chamber

51 Insertion hole

52 Liquid delivery path

53 The wall of the liquid chamber opposite to the plunger

71 Subject

72 Solenoid switching valve

73 base components

74 spit out block

Claims (13)

1. A droplet ejection device, characterized in that, It comprises: a discharge path forming a discharge port at its front end, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for defining the position of the front end of the plunger. By moving the plunger forward without contacting the outer circumference of the plunger with the side wall of the liquid chamber, it imparts inertial force to the liquid material and discharges it in the form of droplets. By repeatedly performing the process of cutting off the liquid material squeezed out of the outlet by the movement of the plunger, moving the plunger backward and forming a gas-liquid interface in the discharge path, droplets are continuously formed. Furthermore, by moving the plunger forward without contacting the inner surface of the liquid chamber at the front end of the plunger, inertial force is applied to the liquid material, which is then discharged in the form of droplets. 2. The droplet ejection device as described in claim 1, characterized in that, The discharge route consists of a first flow path forming the discharge outlet at the front end, and a second flow path that is connected to the first flow path and the liquid chamber and has a diameter larger than the first flow path. A gas-liquid interface is formed in the first or second flow path of the discharge path. 3. A droplet ejection device, characterized in that, It comprises: a discharge path forming a discharge port at its front end, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for defining the position of the front end of the plunger. By moving the plunger forward without contacting the inner surface of the liquid chamber, it imparts inertial force to the liquid material and discharges it in the form of droplets. The discharge route consists of a first flow path, whose front end forms the discharge outlet and whose diameter is smaller than that of the plunger, and a second flow path, which communicates with the first flow path and the liquid chamber and has a larger diameter than the plunger at least on the liquid chamber side. The boundary between the first flow path and the second flow path forms a step or an angle. By moving the plunger forward into the second flow path, the amount of liquid material required to form the desired droplet is extruded from the outlet. Then, by moving the plunger backward, the liquid material extruded from the outlet is cut off and a droplet is formed. 4. The droplet ejection device as described in claim 1, 2, or 3, characterized in that, The inner diameter of the discharge port is 10–100 μm. 5. A method for ejecting droplets, characterized in that, This method uses a droplet ejection device to advance the plunger while maintaining a non-contact relationship between the plunger's outer circumference and the side wall of the liquid chamber, thereby imparting inertial force to the liquid material and ejecting it as droplets. The droplet ejection device includes an ejection path forming an ejection port at its front end, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for determining the position of the front end of the plunger. Droplet ejection methods have the following characteristics: The cutting process cuts off the liquid material extruded from the outlet by the movement of the plunger and forms droplets; In the intake process, after the cut-off process, the plunger retracts and moves to form a gas-liquid interface in the discharge path; and A process that continuously forms droplets by repeatedly performing cutting and suction processes. In the cutting process, the plunger is moved forward without contacting the inner surface of the liquid chamber, thereby imparting an inertial force to the liquid material and ejecting it in the form of droplets. 6. The droplet ejection method as described in claim 5, characterized in that, The discharge route consists of a first flow path forming the discharge outlet at the front end, and a second flow path that is connected to the first flow path and the liquid chamber and has a diameter larger than the first flow path. During the intake process, a gas-liquid interface is formed in the first or second flow path of the exhaust path. 7. The droplet ejection method as described in claim 5, characterized in that, The liquid material is a liquid material containing solid substances. The distance between the front end of the plunger and the inner surface of the liquid chamber in the cutting process is set to be greater than that of the solid substance. 8. The droplet ejection method as described in claim 5, characterized in that, In the cutting process, the forward movement distance of the plunger is greater than the distance between the front end of the plunger immediately following the forward movement and the inner surface of the liquid chamber. 9. A method for ejecting droplets, characterized in that, This method uses a droplet ejection device to advance the plunger without contacting the inner surface of the liquid chamber, thereby imparting inertial force to the liquid material and ejecting it as a droplet. The droplet ejection device includes an ejection path forming an ejection port at its front end, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for moving the plunger forward and backward, and a plunger positioning mechanism for determining the position of the front end of the plunger. The discharge route consists of a first flow path, whose front end forms the discharge outlet and whose diameter is smaller than that of the plunger, and a second flow path, which communicates with the first flow path and the liquid chamber and has a larger diameter than the plunger at least on the liquid chamber side. The boundary between the first flow path and the second flow path forms a step or an angle. Droplet ejection methods have the following characteristics: The extrusion process involves advancing the plunger into the second flow path, thereby extruding the required amount of liquid material from the outlet to form the desired droplets; and The cutting process involves cutting off the liquid material extruded from the outlet and forming droplets by moving the plunger backward. 10. The droplet ejection method as described in claim 9, characterized in that, Liquid material is a liquid material containing solid substances. The distance between the front end of the plunger and the inner surface of the liquid chamber in the extrusion process is set to be greater than that of the solid substance. 11. The droplet ejection method as described in claim 9 or 10, characterized in that, In the extrusion process, the forward movement distance of the plunger is greater than the distance between the front end of the plunger immediately following the process and the inner surface of the liquid chamber. 12. The droplet ejection method as described in claim 5, 6, 9 or 10, characterized in that, The inner diameter of the discharge port is 10–100 μm. 13. The droplet ejection method as described in claim 5, 6, 9 or 10, characterized in that, The viscosity of the liquid material is above 10000 mPa·s.