HK1193377B - Droplet discharge device and method - Google Patents

Description

Droplet discharge device and method

Technical Field

The present invention relates to a droplet discharge apparatus and method for discharging a small amount of liquid material, from a low viscosity material such as water, a solvent, or a reagent to a high viscosity material such as a solder paste, a silver paste, or an adhesive, with high accuracy regardless of the content of a filler.

Background

Various techniques have been proposed as a droplet discharge device that discharges a small amount of liquid material from a discharge port by using a reciprocating plunger.

As a type of droplet discharge device that discharges a liquid material by bringing a tip end of a plunger into contact with a valve seat, for example, patent document 1 discloses a droplet discharge device that discharges a liquid material from a nozzle in a state of a droplet by disposing a side surface of a plunger in a non-contact manner in a flow path having a valve seat in the vicinity of an outlet connected to the nozzle and bringing the tip end of the plunger into contact with the valve seat while moving toward the valve seat, as a droplet discharge device that lands on a workpiece after the liquid material is separated from the nozzle.

However, when the plunger is brought into contact with the valve seat, there are problems that the plunger is worn and changes in shape, and that abrasion powder or abrasion pieces are generated to contaminate the liquid material or that the liquid material is sandwiched between the plunger and the valve seat to prevent satisfactory discharge.

Therefore, as a droplet discharge device that discharges a liquid droplet without bringing the tip of a plunger into contact with a valve seat, the applicant has proposed a droplet discharge device that discharges a liquid droplet by applying an inertial force to a liquid material by moving and stopping the advance and retreat of the plunger, and the droplet discharge device is provided with a plunger positioning mechanism that defines the position of the tip of the plunger at the time of stop of the advance and retreat in the vicinity of the inner wall of a liquid chamber in the advance and retreat direction (patent document 2).

Patent document 3 discloses a device in which a pressure wave generated by a rod end surface displaced back and forth in a chamber with a very small stroke (stroke) and high acceleration and large force by a driving device is propagated in a material in the chamber, thereby arranging droplets of a fluid that is discharged from a nozzle opening.

In recent years, however, electronic devices have been reduced in size and weight, and electronic components mounted thereon have been reduced in size and weight. For example, from around 2005, a member having a mounting size of 400 μm × 200 μm called "0402 member" capable of significantly reducing the mounting area was mounted. The 0402 component is mounted by solder printing of a metal plate at present, but there is a problem that the mixing with a large component requires time and effort such as half etching. In addition, there is also a problem that individual control of the coating amount (coating thickness) is required. Therefore, the yield of mounting by printing deteriorates. Further, in order to ensure printability, there are cases where restrictions are imposed on the arrangement of components.

In the liquid droplet ejection apparatus using the reciprocating plunger, since the liquid material can be controlled by the operation of the plunger, these problems do not occur. However, in such a device, it has not been achieved to accurately discharge a liquid such as solder paste required for small parts in a droplet state in a minute amount (for example, a landing diameter of several tens to several hundreds μm) without bringing the plunger into contact with the valve seat.

Documents of the prior art

Patent document

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

Disclosure of Invention

Problems to be solved by the invention

The invention provides a liquid droplet ejecting apparatus using a reciprocating plunger, which can eject a minute amount of liquid droplets with high accuracy without abutting the plunger on an inner wall (valve seat) of a liquid chamber.

In addition, in the same droplet discharge device, it is also a problem to be solved by the present invention to discharge various liquids from low viscosity to high viscosity.

Means for solving the problems

The present invention 1 is a liquid droplet ejection apparatus including an ejection path having a distal end constituting an ejection port, a plunger, a liquid chamber into which the plunger is inserted, a plunger driving mechanism for advancing and retracting the plunger, and a plunger positioning mechanism for specifying a position of the distal end of the plunger, wherein the liquid droplet is ejected by applying an inertial force to the liquid material by advancing and moving the plunger in a state where the distal end of the plunger is not in contact with an inner wall of the liquid chamber, and the liquid material is extruded from the ejection port in an amount necessary for forming a desired liquid droplet by advancing and moving the plunger, and then the liquid material extruded from the ejection port is cut by moving the plunger backward to form a minute amount of liquid droplets.

The feature of the invention 2 is that, in the invention 1, the discharge path is constituted by a flow path 1 whose tip constitutes the discharge port, and a flow path 2 which communicates with the flow path 1 and the liquid chamber and has a larger diameter than the flow path 1.

The feature of the invention 3 is that, in the invention 2, after the liquid material extruded from the discharge port is cut by moving the plunger backward, the plunger is further moved backward to form a gas-liquid interface in the 1 st flow path or the 2 nd flow path of the discharge path, and the movement of the plunger is stopped.

The feature of the invention 4 is that, in the invention 1, after the liquid material extruded from the discharge port is cut by moving the plunger backward, the plunger is further moved backward to form a gas-liquid interface in the discharge path, and the movement of the plunger is stopped.

The feature of the invention 5 is that, in the invention 3 or 4, a gas-liquid interface is formed in the discharge path, and the plunger is moved forward from the position of the plunger at the time of stopping the movement, whereby the liquid material in an amount necessary for forming a desired liquid droplet is extruded from the discharge port, and then the plunger is moved backward, whereby the liquid material extruded from the discharge port is cut off and a minute amount of liquid droplets are continuously formed.

The invention according to claim 6 is characterized in that, in any one of the inventions 1 to 5, the inner diameter of the discharge port is several tens μm or less.

The invention of claim 7 is a droplet discharge method for discharging droplets by applying inertial force to a liquid material by advancing a plunger in a state where a tip end portion of the plunger is not in contact with an inner wall of a liquid chamber using a droplet discharge device, the droplet discharge device including a discharge path having a tip end constituting a discharge port, the plunger, the liquid chamber into which the plunger is inserted, a plunger driving mechanism for advancing and retreating the plunger, and a plunger positioning mechanism for specifying a position of the tip end portion of the plunger, the droplet discharge method including: an extrusion step of extruding a liquid material from the discharge port in an amount necessary for forming a desired droplet by moving the plunger forward; and a cutting step of cutting the liquid material extruded from the discharge port by moving the plunger backward to form a minute amount of droplets.

The 8 th aspect of the present invention is the cutting device of the 7 th aspect of the present invention, further comprising a suction step of retreating the plunger to form a gas-liquid interface in the discharge passage and stop the movement of the plunger after the cutting step.

The feature of the 9 th invention is that, in the 7 th or 8 th invention, the liquid material is a liquid material containing a solid substance, and the distance between the distal end portion 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 invention according to claim 10 is characterized in that, in any one of the inventions according to claims 7 to 9, the inner diameter of the discharge port is several tens μm or less.

The 11 th invention is characterized in that, in any of the 7 th to 10 th inventions, the viscosity of the liquid material is 10000 mPas or more.

The 12 th invention is characterized in that, in any one of the 7 th to 11 th inventions, a forward movement distance of the plunger in the extrusion step is longer than a distance between a tip end portion of the plunger immediately after the extrusion step and an inner wall of the liquid chamber. Here, the forward movement distance of the plunger in the extrusion step is preferably 3 times or more, more preferably 6 times or more, and particularly preferably 10 times or more, the distance between the distal end portion of the plunger immediately after the extrusion step and the inner wall of the liquid chamber.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to accurately discharge a very small amount of liquid droplets that have not been discharged without bringing a plunger (valve body) into contact with an inner wall (valve seat) of a liquid chamber.

Further, since the valve body does not contact the valve seat, no friction plate or particle (particle) is generated, and there is no fear that these particles are mixed into the material, and a small amount of discharge without contamination can be performed.

Further, even when the liquid material contains a solid substance such as a filler (filler), the liquid material can be discharged without losing the function and properties of the liquid material while preventing the discharge accuracy from being lowered due to crushing or breakage of the solid substance.

Drawings

Fig. 1 is a side cross-sectional view of a main part of a droplet discharge device for explaining a relationship between a position of a plunger and a state of a liquid material, where (a) shows a 1 st stage, (b) shows a 2 nd stage, (c) shows a 3 rd stage, (d) shows a 4 th stage, (e) shows a 5 th stage, (f) shows a 6 th stage, (g) shows a 7 th stage, and (h) shows a 8 th stage.

Fig. 2 shows a modified configuration example of the shapes of the plunger and the discharge path, (a) shows a 1 st configuration example, (b) shows a 2 nd configuration example, (c) shows a 3 rd configuration example, (d) shows a 4 th configuration example, (e) shows a 5 th configuration example, (f) shows a 6 th configuration example, (g) shows a 7 th configuration example, and (h) shows an 8 th configuration example.

Fig. 3 is a side cross-sectional view of a droplet discharge apparatus including a plunger positioning mechanism, in which (a) shows a state in which a moving member is moved in and out, and (b) shows a state in which the moving member is moved back.

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 advancing and retreating direction of a plunger by advancing and retreating the plunger, the plunger being inserted into an insertion hole communicating with a liquid chamber and the distal end of the plunger being moved forward and retreating without contacting the inner wall of the liquid chamber. By using the technique of the present invention, a liquid material having a low viscosity or a high viscosity can be discharged from the discharge port in a droplet state with high accuracy and in a very small amount regardless of the content of the filler.

According to the present invention, a small amount of liquid material, which is a low-viscosity material such as water, a solvent, or a reagent, to a high-viscosity material such as a solder paste, a silver paste, or an adhesive, can be discharged. The present invention has a feature that the present invention can be applied to a high-viscosity liquid material which is not suitable for discharge in ink jet such as solder paste (clear holder). The high-viscosity liquid material is, for example, a liquid having a viscosity of 10000 to 500000 mPas. In particular, it has not been possible to discharge a liquid having a viscosity of 20000 to 500000 mPas, more specifically 30000 to 500000 mPas, in a droplet form in a small amount without bringing the plunger (valve element) into contact with the inner wall (valve seat) of the liquid chamber.

The term "discharge of a minute amount" in the present invention means, for example, discharge of droplets having a landing diameter of several tens to several hundreds of μm or droplets having a volume of 1nl or less (preferably 0.1 to 0.5nl or less). The present invention has a feature that droplets can be formed even with a discharge diameter of several tens of μm or less (preferably 30 μm or less).

An example of a mode for carrying out the present invention will be described below with reference to fig. 1.

Fig. 1 is a main part sectional view of a droplet discharge device (dispenser). First, the structure of a main part (ejection part) of the droplet ejection apparatus will be described.

The discharge portion shown in fig. 1 includes a plunger (plunger) 30, a liquid chamber 50, an insertion hole 51, a liquid feeding path 52, and a discharge path 12.

The liquid chamber 50 is a space filled with a liquid material in which the leading end portion 31 of the plunger is located. The liquid chamber 50 shown in fig. 1 has an upper surface, a side surface, and a bottom surface, and is formed in a cylindrical shape.

An insertion hole 51 is provided in the upper surface of the liquid chamber 50. The plunger 30 is inserted into the insertion hole 51, and the tip of the plunger 30 is positioned 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, and linearly moves forward so as to move closer to or farther from the discharge path 12. In fig. 1, the shape of the tip portion 31 is a plane, but the present invention is not limited to this, and for example, the tip portion may be spherical, concave, tapered, or provided with a projection at a position facing the discharge path 12. Fig. 2 (a) to (g) show examples of the shape of the distal end 31 of the plunger.

A liquid feed path 52 is provided on a side surface of the liquid chamber 50. The liquid material is supplied to the liquid chamber 50 from a liquid material supply unit such as a liquid material storage container, not shown, via the liquid supply path 52.

The liquid chamber 50 is provided with a discharge path 12 on the bottom surface thereof, which communicates with the outside. The liquid material is discharged from the discharge port 11 at the tip of the discharge path 12 to the outside by the 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 be a shape provided with a taper such that the tip is tapered (see fig. 2 (e) and (g)). Further, the flow path 1 may have a discharge port and the flow path 2 may have a larger diameter than the flow path 1 (see fig. 2 f), and in this case, the flow path 2 may have a truncated conical shape (see fig. 2 a to d). When the liquid chamber side is made larger in diameter than the discharge port side of the discharge path, the liquid material flowing into the discharge path is accelerated.

If the length of the discharge path is too long, the droplet cannot be cut satisfactorily, and this problem is likely to occur particularly in a high-viscosity liquid material. Therefore, the discharge path 12 is preferably formed by an orifice (orifice) provided in the wall surface 53 in the liquid chamber. The length of the discharge path is, for example, 100 to 1000. mu.m. Further, a recess having a larger diameter than the plunger 30 may be provided in the wall surface 53 in the liquid chamber, and a surface facing the distal end 31 of the plunger may be formed at a position closer to the discharge port. At this time, the discharge path 12 is formed from the surface in the recess facing the tip end 31 of the plunger to the discharge port 11 (see fig. 2 (f)). The wall surface 53 may be a thin curved surface at the center of the discharge path 12 (see fig. 2 g).

Examples of the plunger driving mechanism include a motor, an elastic body such as a piezoelectric element or a spring, and an actuator using air pressure or the like. The plunger drive mechanism can be appropriately used according to the application, but when it is desired to discharge various liquids having low viscosity and high viscosity, it is preferable to use a mechanism (drive mechanism other than the piezoelectric element) capable of adjusting the stroke of the plunger within a certain range. The stroke of the plunger when discharging a small amount of liquid is, for example, 5 to 1000 μm, but it is preferable to lengthen the stroke when discharging a high-viscosity liquid, for example, 50 to 1000 μm.

The position of the front end of the plunger at the most advanced position is defined by the plunger positioning mechanism. In order to impart a sufficient inertial force to the liquid material in the advancing and retreating direction of the plunger, the distance between the end surface of the plunger and the wall surface 53 of the liquid chamber facing the distal end portion 31 of the plunger is preferably set sufficiently narrow. Since the force applied to the liquid material by the plunger needs to be increased as the inner diameter of the discharge path (nozzle) is decreased, the distance (gap) between the end surface of the plunger and the wall surface of the liquid chamber also needs to be decreased.

For example, in order to form a droplet having a landing diameter of 300 μm or less 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 of a solid substance containing a filler or the like in the liquid material, the most advanced position is set so that the gap is larger than the solid substance. For example, in the case of a solder paste in which the liquid material is particles having an average particle diameter of 10 μm, the gap needs to be larger than 10 μm (it is preferable to make the gap 1.5 times or more the size (particle diameter) of the solid substance). This is because particles of the solder are crushed and stacked in the vicinity of the inlet of the discharge path, which causes a problem that the discharge accuracy is significantly lowered.

The plunger positioning mechanism also defines the position of the front end of the plunger in the final retracted position. This is because, when a liquid material having a low viscosity is discharged, an inertial force necessary for forming a droplet can be given by moving the plunger at a certain speed, but when a liquid material having a high viscosity is discharged, the stroke needs to be set longer in order to move the plunger at a higher speed. Generally, when a small amount of a liquid having a high viscosity (for example, a liquid having a viscosity of 10000mPa · s or more) is discharged, the stroke needs to be set to be sufficiently larger than the gap. The stroke of the plunger is preferably 3 times or more, more preferably 6 times or more, and particularly preferably 10 times or more, the clearance at the most advanced position.

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 most advanced position of the plunger is determined in the following order.

First, the electromagnetic switching valve 72 is switched to a state in which the outside communicates with the front piston chamber 43, and the moving member 40 is rotated to bring the moving member 40 into a state of moving to the forefront. Since the front piston chamber 43 is opened to the outside, the piston 33 is moved forward with respect to the main body 71 by the coil spring 45, and the front contact portion 32 comes into contact with the front stopper (stopper) 41 and stops. Next, the micrometer (micrometer) 69 is rotated to advance the rear stopper 42 to contact the rear contact portion 34, thereby fixing the plunger 30 and the body 71.

The forward moving body 71 is fixed in a state where the rear stopper 42 is in contact with the rear contact portion 34. The tip end 31 of the plunger 30 is fixed at a contact position 13 where it contacts the inner wall of the liquid chamber 50. The moving member 40 is rotated to move only the moving member 40 rearward and define the most advanced position, and the driving unit 70 is fixed to the base member 73.

Through the above operation, the advance/retreat stop position of the plunger 30 can be adjusted to a desired position at which the distal end portion 31 of the plunger 30 does not contact the liquid chamber 50.

The most retracted position of the plunger is determined in the following order.

The micrometer 46 is rotated to retract the rear stopper 42, and the amount of retraction of the plunger 30 during discharge is determined. When the amount of movement of the plunger 30 during retraction is determined, the micrometer 46 is fixed by a rotation lock member such as a fixing screw, not shown, so that the micrometer 46 does not rotate. By the above operation, the operation of setting the final retracted position of the plunger 30 is completed.

The droplet discharge device of the present invention is typically used to discharge a liquid material while relatively moving a workpiece and a discharge port. The droplet discharge device is attached to an XYZ drive mechanism and moves relative to a table on which a workpiece is placed. In the present invention, since the liquid is separated from the discharge port as a droplet and landed on the workpiece, the discharge port can be horizontally moved while being held at a constant height.

If one droplet is discharged at one working position, a desired amount may be secured by discharging a plurality of droplets to the same location. Since the landing diameter is widened if the discharge amount per shot (shot) is increased, in the case where it is not intended to widen the landing diameter, it is preferable to secure a desired amount in several shots. The liquid droplet ejection device of the present invention can eject a small amount of liquid continuously at a high speed, and can operate at a high beat rate of 100 or more shots per second, for example.

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

Fig. 1 (a) shows an initial state at the start of the ejection operation. In this initial state, the distal end portion 31 of the plunger 30 is located at an operation start position which is the farthest position from the discharge path 12 in a series of discharge operations. The liquid chamber 50 and the discharge path 12 are filled with the liquid material. At this time, the discharge port 11 side of the discharge path 12 may be in a state where a slight amount of outside air (air) is sucked.

Fig. 1 (b) shows a state in which the plunger is moved forward from the operation start position of the plunger in fig. 1 (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 liquid material in the liquid chamber 50 is fed into the discharge path 12 by the forward movement of the plunger 30, and the liquid material in the discharge path 12 reaches the discharge port 11 at the tip of the discharge path 12. This causes the outside air (air) present in the discharge passage 12 to be discharged to the outside.

Fig. 1 (c) shows a state in which the plunger is further advanced from the position of the plunger in fig. 1 (b). In this state, the liquid material reaching the discharge port is extruded without being cut to the outside of the discharge port.

Fig. 1 (d) shows a state in which the forward movement of the plunger is stopped after the plunger is further moved forward from the position of the plunger in fig. 1 (c).

At this time, the liquid material is not cut from the liquid chamber 50 to the forefront, but is further pushed out from the discharge port 11, which is the tip of the discharge path 12, to the outside.

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

In this state, the tip end portion 31 of the plunger 30 is located at the most advanced position with respect to the closest position of the discharge path 12 in a series of discharge operations. When the plunger 30 moves to the most advanced position, the liquid material is pushed out to the outside of the discharge port 11 in an amount necessary to form droplets of a desired size. The most advanced position differs depending on the type of liquid material or the size of the formed liquid droplet, but in either case, the tip end portion 31 of the plunger 30 does not contact the inner surface of the liquid chamber.

Fig. 1 e shows a state where the plunger is slightly moved backward from the position (most advanced position) of the plunger in fig. 1 d.

When the plunger 30 moves backward, the proportion of the volume of the plunger occupying the liquid chamber 50 decreases, and a force in the direction toward the inside of the liquid chamber 50 acts on the liquid material in the discharge path 12. Accordingly, the force of pulling back into the discharge path 12 also acts on the liquid material present outside the discharge port 11 (the extruded liquid material connected to the liquid material in the discharge path 12). Therefore, the liquid material extruded from the discharge port is acted upon by an inertial force in the forward direction of the plunger and acted upon by a force in the backward direction of the plunger, and the formation of droplets is started. That is, the liquid material extruded from the discharge port 11 connected to the liquid material in the discharge path 12 is cut off at a portion near the discharge port.

Fig. 1 (f) shows a state where the plunger is further moved backward from the position of the plunger in fig. 1 (e).

When the plunger 30 is further moved backward, the cutting action with respect to the liquid material extruded from the discharge port 11 is further enhanced. Thereby, the liquid material extruded from the discharge port 11 continuous with the discharge path 12 is cut at a portion near the discharge port, and droplets are formed.

In fig. 1 (f), the vicinity of the cutting position of the liquid material on the side continuing from the discharge path 12 and the vicinity of the cutting position of the liquid material on the side having been cut are both depicted as filaments. Generally, such a thread-like form is often found in a highly viscous material, but such a thread-like form is not necessarily shown because it is a highly viscous material depending on the characteristics of the material, environmental conditions such as temperature and humidity, and the like.

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

The discharge port 11 side of the discharge path 12 is preferably provided for the next discharge and is preferably in a state where a slight amount of outside air (air) is sucked. That is, the gas-liquid interface is preferably present in the discharge path 12. By doing so, it is possible to prevent the liquid material from drying out, and to prevent the surrounding environment from being contaminated by liquid drops during standby for the discharge operation. Note here that outside air (air) is not sucked into the liquid chamber 50 beyond the discharge passage 12. This is because the discharge accuracy is adversely affected by the intake of outside air (air) into the liquid chamber 50.

In the case where the discharge passage 12 includes the 1 st passage 21 and the 2 nd passage 22, and the boundary between the 1 st passage 21 and the 2 nd passage 22 does not form a step, the gas-liquid interface may be present in the 1 st passage 21, the 2 nd passage 22, or any of the boundaries thereof (for example, in the case of the passage shapes as shown in fig. 2 (a) and (b)). As shown in fig. 2 (f), even when the boundary between the 1 st passage 21 and the 2 nd passage 22 forms a step, if no air bubbles are formed, the outside air (air) can be sucked into the 2 nd passage 22. Further, the boundary between the cylindrical 1 st channel 21 and the cylindrical 2 nd channel 22 may be smoothly connected to each other by a taper.

Fig. 1 (h) shows a state where the plunger is moved backward from the position of the plunger in fig. 1 (g) to become an operation end position. Fig. 1 (a) to (h) show a series of operations for forming one droplet. The position of the plunger at the time of ending one discharge is set to a position retreated from the most advanced position. In this state, a slight amount of outside air (air) is sucked into the discharge port 11 side of the discharge path 12. Even if outside air (air) is sucked into the discharge path 12, the problem of air bubbles does not occur until the air reaches the liquid chamber 50. When the outside air flows into the liquid chamber 50, the outside air causes variations in the discharge amount, and therefore needs to be avoided. In order to continuously perform the next discharge operation, it is preferable that the operation end position of the plunger be set as the operation start position.

When the discharge operation is completely finished, it is preferable that the discharge path 12 be closed by the tip end 31 of the plunger 30 to prevent the liquid material from flowing out of the discharge port 11.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples at all.

Example 1

The droplet was formed using the droplet discharge device shown in fig. 1. The liquid material used in example 1 was a solder paste (viscosity 45000mPa · s) containing a filler with an average particle size of 6 μm. The amount of 1 droplet discharged in this example was 0.2nl, and the landing diameter was 120 μm. When several tens of droplets were formed on the workpiece at a beat of 100 shots per second while relatively moving the workpiece and the discharge port, and the measurement was performed by the measuring device, it was possible to confirm that dots having a uniform shape were formed.

Example 2

The droplet was formed using the droplet discharge device shown in fig. 1. The liquid material used in example 2 was an Ag paste (viscosity 28000 mPas) containing a 1 to 10 μm framework filler. The amount of 1 droplet discharged in this example was 0.17nl, and the landing diameter was 100 μm. Several tens of droplets were formed on the workpiece at a beat of 250 shots per second while relatively moving the workpiece and the discharge port, and after measurement by the measuring instrument, it was possible to confirm that dots having a uniform shape were formed.

Industrial applicability

According to the present invention, a plunger (valve body) can be accurately discharged in a very small amount of a material which is difficult to discharge in the electronic and semiconductor markets without abutting the plunger (valve body) on the inner wall (valve seat) of the liquid chamber. For example, a paste material containing a soft metal material such as solder paste may not be crushed, and the paste material may be continuously discharged without clogging the discharge device. The present invention is widely applicable to a mounting process for small components on a substrate, a manufacturing process for a solar cell, and the like.

Further, since the valve body does not contact the valve seat, there is no possibility that friction plates or particles are generated and mixed into the material (i.e., no contamination), and therefore, the valve body is also suitable for use in the food and pharmaceutical industries.

Further, since particles, solid substances, gels, structures, and the like of the filler and the like are ejected without unnecessarily breaking the structure, clogging of the nozzle by these broken substances can be effectively prevented.

Description of the symbols

11 discharge port

12 discharge path

13 contact position

21 1 st flow path

22 2 nd flow path

30 plunger

31 front end part

32 forward contact part

33 piston

34 rear abutment

40 moving member

41 front stop

42 rear stop

43 front piston chamber

44 rear piston chamber

45 coil spring

46 micrometer

50 liquid chamber

51 is inserted into the hole

52 liquid feeding path

53 wall surface of liquid chamber facing plunger

71 main body

72 electromagnetic switching valve

73 base component

74 spitting block

Claims (11)

1. A droplet discharge device characterized in that,

the disclosed device is provided with: a discharge path having a front end constituting a discharge port, a plunger, a liquid chamber into which the plunger is inserted, a plunger driving mechanism for advancing and retreating the plunger, and a plunger positioning mechanism for specifying a position of a front end of the plunger, wherein the liquid material is discharged in a state of liquid droplets by applying an inertial force to the liquid material by advancing and moving the plunger in a state where the front end of the plunger is not in contact with an inner surface of the liquid chamber,

the liquid material is extruded from the discharge port in an amount necessary for forming a desired droplet by moving the plunger forward, and then the liquid material extruded from the discharge port is cut by moving the plunger backward to form a minute amount of droplets,

after the liquid material extruded from the discharge port is cut by moving the plunger backward, the plunger is further moved backward to form a gas-liquid interface in the discharge path, and the movement of the plunger is stopped.

2. The droplet ejection apparatus according to claim 1,

the discharge path is composed of a 1 st flow path whose tip constitutes a discharge port, and a 2 nd flow path which communicates with the 1 st flow path and the liquid chamber and has a larger diameter than the 1 st flow path.

3. The droplet ejection apparatus according to claim 2,

after the liquid material extruded from the discharge port is cut by moving the plunger backward, the plunger is further moved backward to form a gas-liquid interface in the 1 st flow path or the 2 nd flow path of the discharge path, and the movement of the plunger is stopped.

4. The droplet ejection apparatus according to any one of claims 1 to 3,

a gas-liquid interface is formed in the discharge path, and the plunger is advanced from the position of the plunger at the time of stopping the movement, so that the liquid material is extruded from the discharge port in an amount necessary for forming a desired droplet, and then the plunger is retreated, so that the liquid material extruded from the discharge port is cut and a minute amount of droplets are continuously formed.

5. The droplet ejection apparatus according to any one of claims 1 to 3,

the inner diameter of the discharge port is 10 to 100 μm.

6. A method of discharging a liquid droplet, characterized in that,

a liquid droplet ejecting method for ejecting liquid droplets by moving a plunger forward while a tip end portion of the plunger is not in contact with an inner surface of a liquid chamber by using a liquid droplet ejecting apparatus,

the liquid droplet ejection device comprises an ejection path having a tip constituting an ejection port, a plunger, a liquid chamber into which the plunger is inserted, a plunger drive mechanism for advancing and retreating the plunger, and a plunger positioning mechanism for specifying the position of the tip of the plunger,

the liquid droplet ejecting method includes:

an extrusion step of extruding a liquid material from the discharge port in an amount necessary for forming a desired droplet by moving the plunger forward;

a cutting step of cutting the liquid material extruded from the discharge port by moving the plunger backward to form a minute amount of droplets; and

and a suction step of, after the cutting step, further retreating the plunger to form a gas-liquid interface in the discharge passage and stop the movement of the plunger.

7. The liquid droplet ejecting method according to claim 6,

the discharge path is composed of a 1 st flow path whose tip constitutes a discharge port, and a 2 nd flow path which communicates with the 1 st flow path and the liquid chamber and has a diameter larger than that of the 1 st flow path,

in the suction step, the plunger is moved backward to form a gas-liquid interface in the 1 st flow path or the 2 nd flow path of the discharge path, and the movement of the plunger is stopped.

8. The liquid droplet ejecting method according to claim 6 or 7,

the liquid material is a liquid material containing a solid substance, and the distance between the distal end of the plunger and the inner surface of the liquid chamber in the extrusion step is set to be larger than the solid substance.

9. The liquid droplet ejecting method according to claim 6 or 7,

the inner diameter of the discharge port is 10 to 100 μm.

10. The liquid droplet ejecting method according to claim 6 or 7,

the viscosity of the liquid material is 10000 mPas or more.

11. The liquid droplet ejecting method according to claim 6 or 7,

the forward movement distance of the plunger in the extrusion step is longer than the distance between the front end of the plunger immediately after the extrusion step and the inner surface of the liquid chamber.