Droplet ejecting apparatus

Abstract

The liquid droplet ejection device (1) is provided with: a liquid chamber (12) in which liquid ejected from a nozzle (10) is stored; and a plunger (11) that moves forward and backward inside the liquid chamber (12), and the distance between the tip of the plunger (11) and the bottom surface inside the liquid chamber (12) is greater than the maximum distance between the side surface of the plunger (11) and the inner surface of the liquid chamber (12) at a position where the plunger (11) moves forward to the nozzle (10) to the maximum extent.

Description

Technical Field

[0001] The present disclosure relates to a liquid droplet ejection device. Background Art

[0002] In recent years, as electronic devices have become increasingly smaller and lighter, the electronic components they incorporate have also been miniaturized and lightweight. For example, 0402 components, with a footprint of 400μm x 200μm, which significantly reduce mounting area, began to be incorporated into electronic devices around 2005.

[0003] Currently, 0402 components are mounted using solder printing on metal plates. However, this presents challenges, such as requiring consideration of half-etching when mixed with larger components. Furthermore, there is the need to individually control the coating amount (coating thickness). Consequently, the yield of printed mounting is low. Furthermore, ensuring printability sometimes imposes constraints on component placement.

[0004] Droplet ejection devices using a reciprocating plunger do not encounter these issues because the liquid material can be controlled by the action of the plunger. However, such devices suffer from the following problem: when the plunger abuts the inner wall of the liquid chamber, it crushes solder particles, which clog the nozzle and prevent ejection.

[0005] Therefore, among conventional droplet ejection devices that use a reciprocating plunger, there are droplet ejection devices that can eject minute amounts of droplets without causing the plunger to abut against the inner wall of a liquid chamber (see, for example, Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 6177291 Summary of the Invention

[0009] One embodiment of the droplet ejection device disclosed herein comprises: a liquid chamber, which stores liquid containing particles and is ejected from a nozzle; and a plunger, which moves back and forth within the liquid chamber, wherein, at a position where the plunger is most advanced toward the nozzle, the distance between the front end of the plunger and the bottom surface of the liquid chamber is greater than the maximum distance between the side surface of the plunger and the inner surface of the liquid chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A This is a cross-sectional view showing an example of a structure in which the plunger of the liquid droplet ejection device 1 is located at the displacement starting end.

[0011] Figure 1BThis is a cross-sectional view showing an example of a structure in which the plunger of the liquid droplet ejection device 1 is located at the end of its displacement.

[0012] Figure 2A It shows Figure 1A The dotted line C is a partial cross-sectional view of the valve mechanism with the plunger 11 located at the starting end of the displacement.

[0013] Figure 2B It shows Figure 1B The dashed line C is a partial cross-sectional view of the valve mechanism where the plunger 11 is located at the displacement terminal.

[0014] Figure 3 3 is a cross-sectional view showing the plunger 31 according to Modification 1.

[0015] Figure 4 4 is a cross-sectional view showing a plunger 41 according to a second modification.

[0016] Figure 5 4 is a cross-sectional view showing a plunger 51 according to a third modification.

[0017] Figure 6 1 is a cross-sectional view showing a valve mechanism 61 according to a fourth modification.

[0018] Figure 7 4 is a cross-sectional view showing a liquid chamber 71 according to a fifth modification. DETAILED DESCRIPTION

[0019] In the structure of patent document 1, although the plunger does not abut against the inner wall of the liquid chamber, as a result, in addition to crushing the solder, there is a problem of fluctuation in the discharge volume due to fluctuations in the amount of air mixed in when filling the fluid into the droplet discharge device, changes over time, and changes in physical properties such as the viscosity of the fluid caused by the coating environment.

[0020] The reasons for this are: The pressure inside the liquid chamber must be high to discharge solder without the plunger contacting the inner wall of the liquid chamber near the nozzle; Furthermore, the clearance between the plunger and the inner wall of the liquid chamber near the nozzle must be rapidly reduced to 1 / 3 to 1 / 10, compressing the solder. Furthermore, to prevent the high pressure from escaping from the nozzle, the plunger must be brought within 100 μm of the inner wall of the liquid chamber near the nozzle, creating a fluid resistance effect through throttling. At this point, the surface of the throttling portion at the plunger's tip displaces with a component perpendicular to the inner wall of the liquid chamber, causing a force that crushes the solder particles against the inner wall, thereby crushing the solder particles.

[0021] The present disclosure is completed to solve such problems, and its purpose is to provide a droplet ejection device as follows: while the plunger does not abut the inner wall of the liquid chamber near the nozzle and the plunger is displaced in a direction that makes it difficult for the force acting on the inner wall of the liquid chamber to crush the solder particles, the pressure required for ejection is generated, and a throttling portion is formed to prevent the escape of this pressure, thereby enabling ejection without crushing the solder particles. On this basis, the ejection amount is adjusted by controlling the displacement of the plunger, thereby enabling the control of the ejection amount of minute droplets.

[0022] The following describes the embodiments of the present disclosure with reference to the accompanying drawings. It should be noted that the embodiments described below each represent a specific example of the present disclosure. Therefore, the numerical values, constituent elements, configuration positions of constituent elements, connection methods, steps, and the order of steps shown in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, the constituent elements of the following embodiments that are not recorded in the independent technical solutions are described as arbitrary constituent elements.

[0023] In addition, each figure is a schematic diagram and does not necessarily illustrate the diagram accurately. It should be noted that in each figure, the same reference numerals are given to substantially the same structures, and repeated descriptions are omitted or simplified.

[0024] (Implementation Method)

[0025] First, use Figure 1A as well as Figure 1B The structure of the liquid droplet ejection device 1 according to the embodiment will be described. Figure 1A 1 is a cross-sectional view showing an example of a structure in which the plunger 11 of the liquid droplet ejecting device 1 is located at the displacement starting end. Figure 1B This is a cross-sectional view showing an example of a structure in which the plunger 11 of the liquid droplet ejection device 1 is located at the end of its displacement.

[0026] The liquid droplet ejection device 1 includes a nozzle 10 , a plunger 11 , a liquid chamber 12 , a supply path 13 , a guide 14 , a displacement amplification mechanism 15 , and an actuator 16 .

[0027] Nozzle 10 forms a nozzle and ejects liquid. The liquid contains particles such as solder particles. Nozzle 10 is located on the bottom surface of the fluid storage space within liquid chamber 12. The shape of nozzle 10 can be cylindrical, conical, or rectangular.

[0028] The plunger 11 passes through Figure 1A as well as Figure 1B The plunger 11 advances and retreats in the Z direction to change the pressure in the liquid chamber 12. In addition, the flow resistance to the liquid flowing from the supply path 13 to the liquid chamber 12 or the liquid flowing from the liquid chamber 12 to the supply path 13 can be increased or decreased by advancing and retreating in the Z direction.

[0029] So, for example Figure 1A as well as Figure 1B As shown, when the plunger 11 is displaced in the -Z direction at high speed, the liquid in the liquid chamber 12 is compressed, causing the pressure to rise.

[0030] In addition, at the position where the plunger 11 moves most toward the nozzle 10 (displacement terminal position), the distance between the front end of the plunger 11 and the bottom surface of the liquid chamber 12 is larger than the maximum distance between the side surface of the plunger 11 and the inner surface of the liquid chamber 12.

[0031] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 12 to the supply path 13 , thereby making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 12 .

[0032] Here, while the plunger 11 is positioned to penetrate the interior of the liquid chamber 12, it does not abut the inner wall of the liquid chamber 12, maintaining a gap (clearance) of at least a certain distance. For inks containing particles, this gap is equal to or larger than the particle diameter. However, for inks not containing particles, a gap of at least 2 μm is sufficient. The shape of the plunger 11 can be a polygonal prism, such as a quadrangular prism or a hexagonal prism, in addition to a cylinder.

[0033] Furthermore, in order to obtain the above-mentioned effects, the opening degree of the opening connecting the interior of the liquid chamber 12 and the supply path 13 is changed when the plunger 11 is at the displacement start position and at the displacement end position.

[0034] That is, the area of ​​the opening covered by the side of the plunger 11 at the position where the plunger 11 has moved most toward the nozzle 10 (the position at the end of displacement) is larger than the area of ​​the opening covered by the side of the plunger 11 at positions other than the position where the plunger 11 has moved most toward the nozzle 10.

[0035] The liquid chamber 12 stores the liquid ejected from the nozzle 10. The liquid chamber 12 compresses the liquid to increase the pressure as the plunger 11 is displaced, thereby maintaining the pressure required to eject the liquid from the nozzle 10. The liquid chamber 12 is connected to the supply path 13.

[0036] Supply path 13 has the function of supplying liquid into liquid chamber 12. To prevent particles from settling and supplying liquid into liquid chamber 12, supply path 13 is formed perpendicularly to the direction (-Z direction) in which liquid is ejected from nozzle 10, or inclined toward the bottom surface of liquid chamber 12 where nozzle 10 is located.

[0037] Since the guide 14 abuts against the plunger 11 , displacement in a direction perpendicular to the direction in which the liquid is ejected from the nozzle 10 (a direction parallel to the XY plane) is restricted, thereby preventing the plunger 11 from abutting against the inner wall of the liquid chamber 12 .

[0038] The displacement amplification mechanism 15 rotates about the Y-axis about the fulcrum 18, amplifying the displacement of the actuator 16 and thereby displacing the plunger 11. The displacement amplification mechanism 15 transmits the displacement and is constructed of a material and shape that provides sufficient rigidity to amplify the displacement of the actuator 16 and maintain the displacement of the plunger 11 even when the plunger 11 is displaced by the reaction force of the liquid stored in the liquid chamber 12.

[0039] The actuator 16 transmits displacement to the displacement amplification mechanism 15, thereby displacing the plunger 11 in the forward and backward directions (Z-axis direction) of the plunger 11. To achieve high responsiveness, the actuator 16 desirably utilizes, for example, a piezoelectric element. However, the actuator 16 is not limited to a piezoelectric element; other means of displacement, such as a solenoid valve or a spring, may also be employed.

[0040] Figure 2A It shows Figure 1A FIG. 1 is a partial cross-sectional view of the valve mechanism in which the portion of the plunger 11 surrounded by the dotted line C is located at the starting end of the displacement. Figure 2B It shows Figure 1B A partial cross-sectional view of the valve mechanism showing the portion of the plunger 11 surrounded by the dotted line C at the end of displacement.

[0041] The plunger 11 is displaced in the -Z direction, compressing the liquid stored in the liquid chamber 12, thereby generating the pressure required for ejection. Furthermore, by reducing the opening 17, the flow resistance to the liquid flowing from the interior of the liquid chamber 12 to the supply path 13 is increased, thereby suppressing the pressure drop inside the liquid chamber 12.

[0042] Although the flow resistance for suppressing the pressure drop is formed by the gap 21 between the inner wall of the liquid chamber 12 around the opening 17 and the plunger 11, since the displacement direction of the plunger 11 is not perpendicular to the wall surface of the liquid chamber 12 forming the gap 21, no force is generated to push the particles in the liquid against the wall surface of the liquid chamber 12, and particles such as solder particles will not be crushed.

[0043] In addition, if Figure 2B As shown, when the plunger 11 is at the position where it has moved most toward the nozzle 10 (displacement terminal position), the distance between the front end of the plunger 11 and the bottom surface of the liquid chamber 12 is greater than the maximum distance between the side surface of the plunger 11 and the inner surface of the liquid chamber 12. Figure 2B As indicated by arrows, particles flow from the liquid chamber 12 through the gap 21 to the supply path 13 .

[0044] This series of effects allows the liquid stored in the liquid chamber 12 to be pressurized without crushing particles such as solder particles, thereby preventing the pressure from decreasing and allowing the liquid containing particles to be stably ejected from the nozzle 10 .

[0045] Furthermore, in the present disclosure, after the pressure in the liquid chamber 12 is increased by the displacement of the plunger 11 in the -Z direction, the high pressure in the liquid chamber 12 is maintained until the plunger 11 is displaced in the +Z direction, thereby enabling continuous fluid discharge from the nozzle. Therefore, by controlling the time between the displacement of the plunger 11 in the -Z direction and the displacement in the +Z direction, the amount of fluid discharged from the nozzle 10 can be controlled.

[0046] Therefore, even if there are fluctuations in the amount of air mixed in when filling the fluid into the droplet ejection device, and changes in the physical properties of the fluid such as viscosity caused by time changes and the coating environment, the desired ejection amount can be achieved by controlling the displacement of the plunger 11 through the waveform of the voltage applied to the actuator 16 composed of the piezoelectric element.

[0047] (Variant 1)

[0048] Next, use Figure 3 Another shape of the plunger 31 according to the first modification will be described. Figure 3 1 is a cross-sectional view showing a plunger 31 according to Modification 1. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0049] A communication channel 32 is formed in the plunger 31. The communication channel 32 extends from the front end 31a of the plunger 31 at the center of the plunger 31 over a constant length in the Z direction. The portion of the communication channel 32 facing the front end 31a of the plunger 31 changes direction at a right angle and extends to the side surface 31b of the plunger 31 in the X-axis direction. While the communication channel 32 is shown here as a right-angled bend, it can also be bent at a different angle.

[0050] The shape of the communication channel 32 on the front end 31a of the plunger 31 is circular, but is not limited to a circular shape and may also be square or another shape. The shape of the communication channel 32 on the side surface 31b is similar. The supply channel 33 is formed from the inner surface 12a of the liquid chamber 12 in the +X direction and is connected to the inner surface 12a of the liquid chamber 12 at the opening 34.

[0051] At the displacement end position of the plunger 31 , the distance between the front end of the plunger 31 and the bottom surface of the liquid chamber 12 is greater than the maximum distance between the side surface of the plunger 31 and the inner surface of the liquid chamber 12 .

[0052] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 12 to the supply path 33 , making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 12 .

[0053] Furthermore, the area of ​​the side surface of the plunger 31 covering the opening 34 at the position where the plunger 31 has moved most toward the nozzle 10 is larger than the area of ​​the side surface of the plunger 31 covering the opening 34 at positions other than the position where the plunger 31 has moved most toward the nozzle 10 .

[0054] Specifically, the plunger 31 is displaced to the displacement end position from a state where the communication channel 32 and the opening 17 are at the same height, thereby reducing the opening of the opening 17 and suppressing the pressure drop in the liquid chamber 12. Furthermore, even if bubbles are generated in the liquid chamber 12, the plunger 31 can be easily removed.

[0055] (Variant 2)

[0056] Next, use Figure 4 Another shape of the plunger 41 according to the second modification will be described. Figure 4 2 is a cross-sectional view showing a plunger 41 according to Modification 2. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0057] The front end 41a of the plunger 41 is formed in a conical shape. It should be noted that the front end 41a of the plunger 41 is not limited to the conical shape, and may be other shapes such as a polygonal pyramid or a hemisphere.

[0058] At the displacement end position of the plunger 41 , the distance between the front end of the plunger 41 and the bottom surface of the liquid chamber 12 is greater than the maximum distance between the side surface of the plunger 31 and the inner surface of the liquid chamber 12 .

[0059] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 12 to the supply path 13 , making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 12 .

[0060] Furthermore, the area of ​​the side surface of the plunger 41 covering the opening 13 at the position where the plunger 41 has moved most toward the nozzle 10 is larger than the area of ​​the side surface of the plunger 41 covering the opening 13 at positions other than the position where the plunger 41 has moved most toward the nozzle 10 .

[0061] Specifically, when the plunger 41 is displaced to the displacement end position, the state in which the opening 13 is not covered by the conical tip 41a changes to a state in which the opening 13 is covered by the side surface of the plunger 41, thereby reducing the opening of the opening 17 and suppressing the pressure drop in the liquid chamber 12. In addition, since the plunger 41 distributes the pressure, it is possible to prevent the particles from being crushed.

[0062] (Variant 3)

[0063] Next, use Figure 5Another shape of the plunger 51 according to the third modification will be described. Figure 5 3 is a cross-sectional view showing a plunger 51 according to Modification 3. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0064] A notch 52 is formed at the front end 51 a of the plunger 51 on the side surface of the plunger 51 on the supply path 13 side.

[0065] The shape of the cutout 52 is formed to be rectangular when viewed from a direction perpendicular to the Y-axis. Note that the shape of the cutout 52 is not limited to this, and may be another shape.

[0066] At the displacement end position of the plunger 51, the distance between the front end of the plunger 51 and the bottom surface of the liquid chamber 12 is greater than the maximum distance between the side surface of the plunger 51 and the inner surface of the liquid chamber 12. Here, the side surface of the plunger 51 is the side surface without the cutout 52 formed.

[0067] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 12 to the supply path 13 , making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 12 .

[0068] Furthermore, the area of ​​the side surface of the plunger 51 covering the opening 13 at the position where the plunger 51 has moved most toward the nozzle 10 is larger than the area of ​​the side surface of the plunger 51 covering the opening 13 at positions other than the position where the plunger 51 has moved most toward the nozzle 10 .

[0069] Specifically, when the plunger 51 is displaced to the displacement terminal position, the state where the opening 13 is not covered by the cutout 52 changes to a state where the opening 13 is covered by the side of the plunger 51, thereby reducing the opening of the opening 17 and suppressing the pressure drop in the liquid chamber 12.

[0070] (Variant 4)

[0071] Next, use Figure 6 The valve mechanism 61 according to the fourth modification will be described. Figure 6 4 is a cross-sectional view showing a valve mechanism 61 according to Modification 4. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0072] The valve mechanism 61 includes an elastic body 63, which is provided on the bottom surface 62a of the liquid chamber 62 so as to cover the side surface 62b. The distal end 11a of the plunger 11 is inserted into the inner side of the elastic body 63 with a gap therebetween. The elastic body 63 is made of rubber or the like, but is not limited to rubber and may also be another elastic body. The provision of the elastic body 63 in the valve mechanism 61 prevents the solder from collapsing.

[0073] At the displacement terminal position of the plunger 11 , the distance between the front end of the plunger 11 and the bottom surface 62 a inside the liquid chamber 62 is larger than the maximum distance between the side surface of the plunger 11 and the inner surface of the liquid chamber 62 which is the surface of the elastic body 63 .

[0074] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 62 to the supply path 13 , making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 62 .

[0075] Furthermore, the area of ​​the side surface of the plunger 11 covering the opening 13 at the position where the plunger 11 has moved most toward the nozzle 10 is larger than the area of ​​the side surface of the plunger 11 covering the opening 13 at positions other than the position where the plunger 11 has moved most toward the nozzle 10 .

[0076] Specifically, by displacing the plunger 11 to the displacement terminal position, the state where the opening 13 is not covered by the side of the plunger 11 changes to the state where the opening 13 is covered by the side of the plunger 11, thereby reducing the opening of the opening 13 and suppressing the pressure drop in the liquid chamber 62.

[0077] (Variant 5)

[0078] Next, use Figure 7 Another shape of the liquid chamber 71 according to Modification 5 will be described. Figure 7 4 is a cross-sectional view showing a liquid chamber 71 according to Modification 5. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0079] Liquid chamber 71 includes side surface 71a disposed above opening 17 of supply passage 13 and side surface 71b disposed below opening 17 of supply passage 13. Side surface 71b of liquid chamber 71 disposed below opening 17 of supply passage 13 is formed to be wider than side surface 71a.

[0080] This makes it possible to facilitate the dispersion of particles and suppress the particles from being concentrated in one place and crushed.

[0081] At the displacement end position of the plunger 11 , the distance between the front end of the plunger 11 and the bottom surface of the liquid chamber 71 is greater than the maximum distance between the side surface of the plunger 11 and the inner surface of the liquid chamber 71 as the side surface 71 a .

[0082] This increases the flow resistance of the liquid flowing out from the interior of the liquid chamber 71 to the supply path 13 , making it difficult for the liquid to flow out, thereby preventing a decrease in the pressure inside the liquid chamber 71 .

[0083] Furthermore, the area of ​​the side surface of the plunger 11 covering the opening 13 at the position where the plunger 11 has moved most toward the nozzle 10 is larger than the area of ​​the side surface of the plunger 11 covering the opening 13 at positions other than the position where the plunger 11 has moved most toward the nozzle 10 .

[0084] Specifically, by displacing the plunger 11 to the displacement terminal position, the state where the opening 13 is not covered by the side 71a of the plunger 11 changes to the state where the opening 13 is covered by the side of the plunger 11, thereby reducing the opening of the opening 13 and suppressing the pressure drop in the liquid chamber 12.

[0085] According to the present disclosure, a fluid containing particles can be ejected without crushing the particles.

[0086] Industrial applicability

[0087] The technology disclosed herein can be widely used in a droplet discharge device that can discharge solder particles without crushing them and can adjust the discharge amount by controlling the displacement of a plunger, thereby controlling the discharge amount of minute droplets.

[0088] Description of Reference Numerals

[0089] 1. Droplet ejection device

[0090] 10 nozzles

[0091] 11 plunger

[0092] 12 liquid chambers

[0093] 13 Supply Road

[0094] 14 guides

[0095] 15 displacement expansion mechanism

[0096] 16 actuators

[0097] 17 opening

[0098] 18 fulcrums.

Claims

1. A liquid droplet ejection device, wherein: The liquid droplet ejection device comprises: a liquid chamber that stores liquid containing particles therein and ejects the liquid from the nozzle; as well as A plunger moves forward and backward inside the liquid chamber, When the plunger is at its most advanced position toward the nozzle, the distance between the front end of the plunger and the bottom surface of the liquid chamber is greater than the maximum distance between the side surface of the plunger and the inner surface of the liquid chamber.

2. The liquid droplet ejection device according to claim 1, wherein: The liquid droplet ejection device further includes a supply path having an opening on the inner surface of the liquid chamber and supplying the liquid into the liquid chamber. The area of ​​the opening covered by the side surface of the plunger at the position where the plunger is most advanced toward the nozzle is larger than the area of ​​the opening covered by the side surface of the plunger at positions other than the position where the plunger is most advanced toward the nozzle.

3. The liquid droplet ejection device according to claim 2, wherein: The plunger has a flow path that is formed from a front end of the plunger in an advancing and retreating direction and is bent to communicate with a side surface of the plunger.

4. The liquid droplet ejection device according to claim 1, wherein: A distance between the side surface of the plunger and an inner surface of the liquid chamber is larger than a particle diameter of the liquid.

5. The liquid droplet ejection device according to claim 1, wherein: The droplet ejection device further comprises: an actuator that displaces the plunger in an advancing and retreating direction; and A displacement amplification mechanism amplifies the displacement of the actuator and transmits the displacement to the plunger.

6. The liquid droplet ejection device according to claim 1 or 5, wherein: The front end of the plunger is in the shape of a cone or a polygonal pyramid.

7. The liquid droplet ejection device according to claim 1 or 5, wherein: A notch is formed on a side surface of the front end of the plunger.

8. The liquid droplet ejection device according to claim 1 or 5, wherein: The droplet ejection device further includes an elastic body at the bottom of the liquid chamber, the elastic body covering the inner surface of the liquid chamber. The front end of the plunger is inserted into the inner side of the elastic body with a gap therebetween.

9. The liquid droplet ejection device according to claim 1 or 5, wherein: The liquid chamber includes a first region and a second region therein. The second region is located closer to the front end of the plunger than the first region. The second region has a width greater than that of the first region.

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