JP7535965B2 - Liquid material application unit, liquid material application device, and liquid material application method - Google Patents

Description

The present disclosure relates to a liquid material application unit, a liquid material application device, and a liquid material application method.

In the mounting process of electronic components, liquid materials such as conductive materials or adhesives are applied. In recent years, due to the miniaturization of electronic components, there is a demand for stable application of extremely small amounts of liquid materials.

In processes where tiny optical components are fixed with adhesives, adhesives made by mixing two liquid materials and hardening them through a chemical reaction are widely used. This is because one-liquid moisture-curing adhesives take a long time to harden.

The process of applying the liquid material to electronic components and the process of applying the adhesive of the two-liquid mixed liquid material are preferably performed using a coating needle, for example, as disclosed in JP 2007-268353 A. In this case, the liquid material in the coating liquid container adheres to the coating needle inside the coating liquid container. The coating needle then protrudes from the through-hole of the coating liquid container, and the liquid material adhered to the coating needle is transferred to the object to be coated. By using a coating needle, it is possible to apply fine patterns to liquid materials with a wide range of viscosities.

JP 2007-268353 A

When applying liquid material using a coating needle, it is important to control the protrusion amount, which is the distance that the coating needle protrudes from the coating liquid container. In other words, if the protrusion amount is excessively long, air bubbles may be mixed into the liquid material in the coating liquid container, and the coating diameter of the applied pattern may vary. Also, if the protrusion amount is excessively short, the coating diameter of the applied pattern may become too large.

The present disclosure has been made in consideration of the above problems. Its purpose is to provide a liquid material application unit, a liquid material application device, and a liquid material application method that can prevent air bubbles from being mixed into the liquid material and can stably supply a pattern with a fine application diameter.

A liquid material application unit according to the present disclosure includes a coating needle and a coating liquid container. The coating needle applies the liquid material. The coating liquid container holds the liquid material inside and has a through hole formed in the bottom for the coating needle to penetrate through. The coating liquid container includes a connecting portion and a needle moving portion. The connecting portion extends along a horizontal direction intersecting the extending direction of the coating needle. The needle moving portion extends from the connecting portion toward the through hole along the up-down direction, which is the extending direction of the coating needle. The protrusion amount by which the coating needle can protrude from the through hole of the coating liquid container along the up-down direction is 1 mm or more and 3 mm or less. The first width in the horizontal direction of the needle moving portion is 5 mm or less. The length by which the needle moving portion extends along the up-down direction from the connecting portion to the through hole is 5 mm or more.

In the liquid material application method according to the present disclosure, the liquid material is held inside a coating liquid container having a through hole formed in the bottom, and the coating liquid container is opposed to an object to which the liquid material is to be applied with the tip of a coating needle immersed in the liquid material. The coating liquid container is brought close to the object to be applied. The coating needle is moved along the extension direction of the coating needle to apply the liquid material to the object to be applied. In the coating step, the amount by which the coating needle can protrude from the through hole of the coating liquid container along the extension direction is 1 mm or more and 3 mm or less. In the approaching step, the coating liquid container is positioned so that at least a portion of it is surrounded by the object to be applied.

The present disclosure provides a liquid material application unit, a liquid material application device, and a liquid material application method that can prevent air bubbles from being mixed into the liquid material and stably supply a pattern with a fine application diameter.

1 is a schematic perspective view of a liquid material application device according to an embodiment of the present invention; 2 is a schematic diagram showing a configuration of a portion of a liquid material application unit according to the present embodiment. FIG. 1 is a schematic front view showing a first example of the configuration of a liquid material application unit according to the present embodiment; 1 is a schematic side view showing a first example of the configuration of a liquid material application unit according to the present embodiment; 5A and 5B are a schematic front view and a schematic side view showing a second example of the configuration of the liquid material application unit of the present embodiment. 13A and 13B are a schematic front view and a schematic side view showing a third example of the configuration of the liquid material application unit of the present embodiment. 7 is a schematic diagram for explaining a cam member of the application mechanism shown in FIG. 6 . 1A to 1C are schematic diagrams illustrating a liquid material applying method using the liquid material applying unit of the present embodiment. 11A to 11C are schematic diagrams illustrating a liquid material applying method using a liquid material applying unit in a comparative example. 10A to 10C are schematic diagrams illustrating a coating process when the protruding amount of the coating needle is normal. FIG. 11 is a schematic diagram for comparison with FIG. 10 showing a coating process when the protruding amount of the coating needle is extremely short. 13 is a graph showing test results of the variation in coating diameter when the protrusion amount is 3 mm. 13 is a graph showing test results of the variation in coating diameter when the protrusion amount is 15 mm. 4 is a schematic diagram showing an initial position of a coating needle in a coating liquid container in a vertical direction. FIG. FIG. 11 is a schematic diagram for explaining a gap position. 16 is a schematic cross-sectional view taken along line XVI-XVI in FIG. 15. FIG. 13 is a schematic diagram showing the mechanism of air bubble inclusion caused by the coating gap. 13 is a flowchart showing a liquid material applying method according to the third embodiment.

The following describes this embodiment with reference to the figures.

Figure 1 is a schematic perspective view of a liquid material application device according to this embodiment. With reference to Figure 1, a liquid material application device 200 according to this embodiment includes a base 12 arranged on a floor surface, an X-axis table 1, a Y-axis table 2, a Z-axis table 3, a liquid material application unit 4, an observation optical system 6, a CCD camera 7 connected to the observation optical system 6, and a control unit 11.

On the upper surface of the base 12, a Y-axis table 2 configured to be movable in the Y-axis direction in FIG. 1 is installed. Specifically, a guide portion is installed on the lower surface of the Y-axis table 2, and is connected so as to be slidable along a guide rail installed on the upper surface of the base 12. A ball screw is also connected to the lower surface of the Y-axis table 2. By operating the ball screw with a driving member such as a motor, the Y-axis table 2 can be moved along the guide rail (in the Y-axis direction). The upper surface of the Y-axis table 2 is also a mounting surface on which the object 5 to be coated is mounted. Note that a thin plate-shaped substrate is shown as the object 5 to be coated in FIG. 1. However, this is merely an example, and the object 5 to be coated may be, for example, the bottom of a groove, as described later.

A gate-shaped structure is provided on the base 12, straddling the guide rail of the Y-axis table 2 in the X-axis direction. On this structure is mounted the X-axis table 1, which is movable in the X-axis direction. The X-axis table 1 can be moved in the X-axis direction, for example, using a ball screw.

The Z-axis table 3 is mounted on the moving body of the X-axis table 1, and a liquid material application unit 4 and an observation optical system 6 are mounted on this Z-axis table 3. The liquid material application unit 4 and the observation optical system 6 can move in the X direction together with the Z-axis table 3. The liquid material application unit 4 is provided to apply the application liquid to the application surface (upper surface side) of the application target 5 using an application needle provided therein. The observation optical system 6 is provided to observe the application position of the application target 5. The CCD camera 7 of the observation optical system 6 converts the observed image into an electrical signal. The Z-axis table 3 supports the liquid material application unit 4 and the observation optical system 6 so that they can move in the Z-axis direction.

The control unit 11 includes an operation panel 8, a monitor 9, and a control computer 10, and controls the X-axis table 1, the Y-axis table 2, the Z-axis table 3, the liquid material application unit 4, and the observation optical system 6. The operation panel 8 is used to input commands to the control computer 10. The monitor 9 displays image data converted by the CCD camera 7 of the observation optical system 6 and output data from the control computer 10.

When drawing a circuit pattern on the object to be coated 5, the position to be drawn on the object to be coated 5 is moved by the X-axis table 1 and the Y-axis table 2 to directly below the observation optical system 6, and the drawing start position is observed and confirmed by the observation optical system 6 to determine the drawing start position. The circuit pattern is then drawn based on the determined drawing start position. From the drawing start position, the object to be coated 5 is moved by the X-axis table 1 and the Y-axis table 2 in sequence so that the drawing position is directly below the liquid material application unit 4. Once the movement is complete, the liquid material application unit 4 is driven to apply the liquid. By continuously repeating this process, the circuit pattern can be drawn.

The relationship between the lowered end position of the coating needle 24 and the focus position of the observation optical system 6 is stored in advance, and when drawing, the position where the image is focused by the observation optical system 6 is used as the Z-axis reference, and the Z-axis table is used to move the coating needle 24 to a height where it contacts the coating target 5, and then coating is performed. If the area of the circuit pattern to be drawn is large and the height of the coating position of the coating target 5 changes significantly during drawing, the focus position is checked midway as necessary and the position in the Z-axis direction is corrected before coating. The focus position can be adjusted at this time by a method of automatically focusing using image processing, or by a method of constantly detecting the height position of the surface of the coating target 5 using a laser sensor or the like and applying corrections in real time.

Next, the liquid material application unit 4 in this embodiment will be described in detail using Figures 2 to 7.

Figure 2 is a schematic diagram showing the configuration of a portion of the liquid material application unit of this embodiment. With reference to Figure 2, the liquid material application unit 4 of this embodiment includes a coating liquid container 21 and a coating needle 24. The coating liquid container 21 holds liquid material 100 therein. The coating liquid container 21 has a through hole 22 formed in its bottom portion, which is the lowest portion in Figure 2. The coating needle 24 is disposed inside the coating liquid container 21 so that it can penetrate therethrough.

The coating needle 24 applies the liquid material 100 in the coating liquid container 21. In FIG. 2, the tip 23, which is the lowest part of the coating needle 24, is immersed in the liquid material 100. When the coating needle 24 is lowered, at least the tip 23 penetrates the through-hole 22 and protrudes from the through-hole 22. In this way, the coating needle 24 applies the liquid material 100 to the object to be coated.

The coating liquid container 21 includes a connecting portion 25 and a needle moving portion 26. As described later, the liquid material coating unit 4 includes a driving portion such as a linear motion mechanism and a servo motor. The connecting portion 25 is a portion that connects a member that constitutes the center of the liquid material coating unit 4, such as the linear motion mechanism, to the coating liquid container 21. In the state of FIG. 2 in which the coating needle 24 can penetrate the coating liquid container 21 from the through hole 22, the connecting portion 25 extends along a horizontal direction (left-right direction in FIG. 2) that intersects with the extension direction of the coating needle 24 passing through the coating liquid container 21 (up-down direction in FIG. 2). On the other hand, the needle moving portion 26 is a portion that extends from the connecting portion 25 toward the through hole 22 along the up-down direction (Z direction in FIG. 1), which is the extension direction of the coating needle 24. In other words, the needle moving portion 26 is a portion that is arranged below the connecting portion 25 in FIG. 2 and extends in the up-down direction below the connecting portion 25. The application needle 24 moves up and down inside the needle movement section 26.

The amount of protrusion P that the coating needle 24 can protrude from the through hole 22 of the coating liquid container 21 in the vertical direction in FIG. 2 is 1 mm or more and 3 mm or less. In other words, when the coating needle 24 in FIG. 2 descends to apply the liquid material 100 to the coating target 5, the amount of protrusion P, which is the distance by which the tip 23 protrudes downward from the through hole 22, is 1 mm or more and 3 mm or less. The state in which the tip 23 protrudes downward from the through hole 22 is shown by a dotted line in FIG. 2. The amount of protrusion P may be 1.5 mm or more and 3 mm or less, and is more preferably 2 mm or more and 3 mm or less. Furthermore, it is even more preferable that the amount of protrusion P is 2.5 mm or more and 3 mm or less. As an example, the amount of protrusion P is 3 mm.

The first width W1 of the needle moving part 26 in the left-right direction in FIG. 2 is 5 mm or less. In other words, the maximum horizontal width of the outer periphery when the needle moving part 26 is viewed in a plan view, for example, from above in FIG. 2 is 5 mm or less. As an example, W1 is 5 mm. When the bottom part of the needle moving part 26 in FIG. 2 has a tapered shape, the first width W1 is the maximum horizontal width of the outer periphery in an area other than the area having the tapered shape of the needle moving part 26, where the maximum width of the outer periphery does not change substantially even when moving in the up-down direction.

The length T of the needle movement part 26 extending in the vertical direction in FIG. 2 from the joint part 25 to the through hole 22 is 5 mm or more. In other words, the needle movement part 26 extends from the bottom of the joint part 25 to a position 5 mm or more below. As an example, this T is 15 mm.

In the liquid material application unit 4 having the above characteristics, the first width W1 is 5 times or less than the second width W2 in the left-right direction in FIG. 2 of the portion of the application needle 24 extending in the vertical direction in FIG. 2. The portion of the application needle 24 extending in the vertical direction in FIG. 2 refers to a region of the application needle 24 where the maximum width of the outer periphery does not change even when moved in the vertical direction, other than a region of the application needle 24 that is inclined by tapering, such as the tip 23 in FIG. 2. In other words, in the region of the second width W2 of the application needle 24, the outer periphery of the application needle 24 extends straight in the vertical direction, and the outer periphery width is constant. The second width W2 means the maximum width in the horizontal direction of the outer periphery when the application needle 24 is viewed in a plan view from above in FIG. 2. As an example, W1 is 5 mm and W2 is 1 mm.

As shown in FIG. 2, the object to be coated 5 is preferably a groove, concave, or container-shaped object having a side portion that can surround the lowered coating needle 24, and a bottom portion that is disposed below the side portion and onto which the liquid material 100 is applied. The lateral distance D of the side portion of the object to be coated 5 that surrounds the processed coating needle 24 is, for example, 6.5 mm or more, and may be 12 mm or 17 mm.

The liquid material 100 may be, for example, a conductive material for mounting a quartz crystal oscillator. Alternatively, the liquid material 100 may be a catalyst material for a so-called MEMS (Micro Electro Mechanical Systems) gas sensor. Furthermore, the liquid material 100 may be an adhesive for an LED (Light Emitting Diode). The liquid material 100 may be a mixture of two liquids.

The liquid material 100 may be a liquid in which fine particles are suspended. For example, if the liquid material 100 is an adhesive, the fine particles may include reinforcing particles of the adhesive. The liquid material 100 is not limited to a pure liquid that does not contain particles, but may be a liquid that contains particles. Specifically, the liquid material 100 may be a conductive paste that uses metal particles used in industrial applications. In this case, the fine particles are metal particles. The liquid material 100 may also be an adhesive that contains inorganic particles. In this case, the fine particles are inorganic particles.

The liquid material 100 in the coating liquid container 21 does not leak out of the through hole 22 due to the balance between the surface tension at the edge of the through hole 22 and the pressure due to the weight of the liquid material 100 in the coating liquid container 21.

Figure 3 is a schematic front view showing a first example of the configuration of the liquid material application unit of this embodiment. Figure 4 is a schematic side view showing a first example of the configuration of the liquid material application unit of this embodiment. With reference to Figures 3 and 4, the liquid material application unit 4 includes, in addition to the application liquid container 21 of Figure 2, a servo motor 120, a motor drive unit 121, a coating needle holder 102, a coating needle holder storage unit 104, a coating needle holder fixing unit 106, and a linear motion mechanism 130.

The servo motor 120 is provided as a drive source for driving the coating needle 24 up and down. The coating needle holder 102 holds one coating needle 24 with a tapered tip. The linear motion mechanism 130 moves the coating needle holder 102 up and down in response to the rotation of the servo motor 120. The motor drive unit 121 controls the rotation of the servo motor 120 so that the coating needle holder 102 moves up and down at an appropriate speed.

The linear motion mechanism 130 includes an origin sensor 118, an eccentric plate 116, an eccentric shaft 114, a linear guide 132, a connecting plate 112, a movable part 108, a connecting shaft 110, and bearings 122 and 124.

The eccentric plate 116 is rotated by the servo motor 120 and is attached to the rotation axis of the servo motor 120 that intersects with the vertical movement direction of the application needle holder 102. The eccentric plate 116 is provided with an eccentric shaft 114 at a position eccentric to the rotation axis of the servo motor 120.

The origin sensor 118 detects the origin provided on the eccentric plate 116 and outputs it to the motor drive unit 121. This origin is closest to the origin sensor 118 when the eccentric plate 116 coincides with the reference rotation angle.

The movable part 108 has a coating needle holder 102 attached to a coating needle holder fixing part 106, and one coating needle 24 is held on the underside of the coating needle holder 102 with its tip 23 facing downward. The linear guide 132 supports the movable part 108 to which the coating needle holder 102 is fixed so that it can move up and down.

The connecting plate 112 connects, at a fixed length, between the connecting shaft 110 and the eccentric shaft 114 provided on the movable part 108, which moves up and down together with the application needle holder 102.

The bearing 122 supports the connecting plate 112 so that it can rotate on the eccentric shaft 114. The bearing 124 supports the connecting plate 112 so that it can rotate on the connecting shaft 110.

The movable part 108 is attracted to the fixed pin 128 via the spring 126, and is configured so that vibrations due to backlash in the bearings 122 and 124 do not occur when the device is driven. It is also possible to configure the device without the spring 126 by applying preload to the bearings 122 and 124 to eliminate backlash.

When the eccentric plate 116 rotates due to the drive of the servo motor 120, the coating needle 24 moves up and down in a reciprocating manner in association with the upward and downward movement of the eccentric shaft 114. When the eccentric plate 116 rotates in one direction, the connecting shaft 110 moves up and down by an amount corresponding to an upward and downward movement stroke ΔZ. In other words, the coating needle 24 moves up and down within the needle movement section 26 in FIG. 2. This causes the tip 23 of the coating needle 24 to reciprocate between applying the liquid material 100 and retreating to the liquid material 100 side after application.

Figure 5 is a schematic front view and a schematic side view showing a second example of the configuration of the liquid material application unit of this embodiment. That is, (A) of Figure 5 is a schematic front view, and (B) of Figure 5 is a schematic side view. Referring to Figure 5, the second example is basically similar in configuration to the first example of Figures 3 and 4, so detailed description will not be repeated. However, as in the second example of Figure 5, the extension direction of the joint part 25 of the application liquid container 21 may be approximately the same as the left-right direction in which the servo motor 120 extends. Alternatively, as in the first example of Figures 3 and 4, the extension direction of the joint part 25 of the application liquid container 21 may be intersecting (for example, approximately perpendicular to) the left-right direction in which the servo motor 120 extends. Note that the liquid material application unit 4 of Figures 3 to 5 converts the rotation of the servo motor 120 into linear motion to move the application needle 24 up and down. However, it is not limited to such an example. For example, the linear reciprocating mechanism of the application needle 24 in Figures 3 to 5 may be any one selected from the group consisting of an electric linear actuator using a screw, an air cylinder using pneumatic pressure, and a solenoid.

6 is a schematic front view and a schematic side view showing a third example of the configuration of the liquid material application unit of this embodiment. That is, FIG. 6 (A) is a schematic front view, and FIG. 6 (B) is a schematic side view. FIG. 7 is a schematic view for explaining the cam member of the application mechanism shown in FIG. 6. With reference to FIG. 6 and FIG. 7, the liquid material application unit 4 of the third example mainly includes a servo motor 120, a cam 143, a bearing 122, a cam connecting plate 145, a movable part 108, and a coating needle holder 102 in addition to the coating liquid container 21 of FIG. 2. The coating needle 24 is held by the coating needle holder 102. The servo motor 120 is installed so that the rotation axis extends in the direction along the Z-axis direction shown in FIG. 1. A cam 143 is connected to the rotation axis of the servo motor 120. The cam 143 is rotatable around the rotation axis of the servo motor 120.

The cam 143 includes a center portion connected to the rotating shaft of the servo motor 120 and a flange portion connected to one end of the center portion. As shown in (A) of FIG. 7, the upper surface of the flange portion (the surface on the servo motor 120 side) is a cam surface 161. This cam surface 161 is formed in an annular shape along the outer periphery of the center portion, and is formed in a slope shape so that the distance from the bottom surface of the flange portion varies. Specifically, as shown in (B) of FIG. 7, the cam surface 161 includes an upper end flat region 162 that is the longest distance from the bottom surface of the flange portion, a lower end flat region 163 that is spaced apart from the upper end flat region 162 and has the smallest distance from the bottom surface of the flange portion, and a slope portion that connects the upper end flat region 162 and the lower end flat region 163. Here, (B) of FIG. 7 is a development view of the flange portion including the cam surface 161 that is arranged in an annular shape so as to surround the center portion, as viewed from the side.

The bearing 122 is arranged so as to contact the cam surface 161 of the cam 143. As shown in (A) in FIG. 6, the bearing 122 is arranged in a specific direction (to the right of the servo motor 120) when viewed from the cam 143, and maintains contact with the cam surface 161 when the cam 143 rotates as a result of the rotation of the rotation shaft of the servo motor 120. A cam connecting plate 145 is connected to the bearing 122. The other end of the cam connecting plate 145, opposite to the one end connected to the bearing 122, is fixed to the movable part 108. The coating needle holder fixing part 106 and the coating needle holder storage part 104 are connected to the movable part 108. The coating needle holder 102 is stored in the coating needle holder storage part 104.

The coating needle holder 102 includes a coating needle 24. The coating needle 24 is arranged so as to protrude from the underside of the coating needle holder 102 (the lower side opposite the side where the servo motor 120 is located). A coating liquid container 21 is arranged below the coating needle holder 102. The coating needle 24 is held in an inserted state in the coating liquid container 21.

A fixed pin 128B is installed on the movable part 108. The other fixed pin 128A is installed on the stand that holds the servo motor 120. A spring 126 is installed to connect the fixed pins 128A and 128B. The movable part 108 is subjected to a tensile force toward the coating liquid container 21 by the spring 126. The tensile force of the spring 126 acts on the bearing 122 via the movable part 108 and the cam connecting plate 145. The tensile force of the spring 126 keeps the bearing 122 pressed against the cam surface 161 of the cam 143.

The movable part 108, the coating needle holder fixing part 106, and the coating needle holder storage part 104 are connected to a linear guide 132 installed on the above-mentioned stand. The linear guide 132 is arranged to extend in the Z-axis direction. Therefore, the movable part 108, the coating needle holder fixing part 106, and the coating needle holder storage part 104 are movable along the Z-axis direction.

Next, the operation of the above-mentioned liquid material application unit 4 will be described. In the above-mentioned liquid material application unit 4, the servo motor 120 is driven to rotate the rotation shaft of the servo motor 120, thereby rotating the cam 143. As a result, the height of the cam surface 161 of the cam 143 in the Z-axis direction changes, and therefore the position in the Z-axis direction of the bearing 122 that is in contact with the cam surface 161 on the right side of the cam 143 in FIG. 6A also changes in response to the rotation of the drive shaft of the servo motor 120.

Then, in response to the positional fluctuation of the bearing 122 in the Z-axis direction, the movable part 108, the coating needle holder fixing part 106, and the coating needle holder storage part 104 move in the Z-axis direction. As a result, the coating needle holder 102 held in the coating needle holder storage part 104 also moves in the Z-axis direction, so that the position of the coating needle 24 installed in the coating needle holder 102 in the Z-axis direction can be changed.

Next, the liquid material application method using the liquid material application unit 4 of this embodiment will be described with reference to FIG. 8.

Figure 8 is a schematic diagram illustrating a liquid material application method using the liquid material application unit of this embodiment. In the liquid material application method of Figure 8, the steps proceed in the order of (A), (B), (C), (D), and (E). Referring to Figure 8, first, as in (A), a liquid material 100 is held inside a coating liquid container 21 of a liquid material application unit 4 having a through hole 22 formed in the lowermost part (bottom part). The coating liquid container 21 in Figure 8 has the same shape and dimensions as the coating liquid container 21 in Figure 2. At least the tip 23 of the coating needle 24 is immersed in the liquid material 100. The area of the coating needle 24 immersed in the liquid material 100 may reach an area that extends straight so that the outer circumferential width is constant, above the tip 23 in Figure 8. In this state, the coating liquid container 21 is arranged to face the bottom surface of the application target 5 of the liquid material 100, for example, a groove-shaped member or a concave-shaped member, in the vertical direction of Figure 8.

Next, as shown in (B), the coating liquid container 21 is brought close to the object to be coated 5. Specifically, the coating liquid container 21 is lowered. As a result, at least a portion of the needle moving part 26 of the coating liquid container 21 is positioned so that it is surrounded by the side surface of the object to be coated 5. In other words, a portion of the needle moving part 26 enters the concave portion of the object to be coated 5 so that the side surface of the object to be coated 5 and the needle moving part 26 overlap each other in the horizontal direction. In further other words, a portion of the needle moving part 26 enters the concave portion of the object to be coated 5 so that the vertical positions of the side surface of the object to be coated 5 and the needle moving part 26 are equal.

Next, as shown in (C), the coating needle 24 is moved along the direction in which the coating needle 24 extends, that is, the vertical direction. That is, as shown in (C), the coating needle 24 is lowered and its tip 23 is brought close to the bottom surface of the coating target 5. As a result, as shown in (D), the liquid material 100 attached to, for example, the tip 23 of the coating needle 24 is applied to the bottom surface of the coating target 5. At this time, as shown in (D), the tip 23 of the coating needle 24 may be lowered until it comes into contact with the coating target 5. Alternatively, the tip 23 of the coating needle 24 may not come into contact with the coating target 5, and may be lowered until the liquid material 100 attached to the coating needle 24 comes into contact with the coating target 5. At this time, the amount of protrusion that the coating needle 24 can protrude from the through hole 22 at the bottom of the coating liquid container 21 along the vertical direction, which is its extension direction, is 1 mm to 3 mm.

After application is complete, the application needle 24 rises as shown in (E). This causes the tip 23 to be stored again in the application liquid container 21. In this application process, it is preferable that the reciprocating movement of the application needle 24 along its extension direction, moving toward the object 5 to be applied (C) and (D), and moving away from the object 5 to be applied (E), is repeated no more than nine times per second. This allows for proper application of the liquid material 100.

Next, the effects of this embodiment will be explained while considering comparative examples and referring to Figures 9 to 11 as appropriate.

9 is a schematic diagram for explaining a liquid material application method using a liquid material application unit in a comparative example. In FIG. 9, the steps proceed in the order of (A), (B), (C), and (D). Referring to FIG. 9, in the comparative example, the first width w1 of the needle moving part 26 is larger and the vertical length t is shorter than in the present embodiment, as shown in (A). The first width w1 is larger than the lateral distance d of the side part of the object to be applied 5. The first width w1 is more than five times the second width w2. For this reason, the comparative example coating liquid container 21 cannot lower to a position where the needle moving part 26 is surrounded by the object to be applied 5. Therefore, as shown in (B), the coating liquid container 21 does not move in the vertical direction, and only the coating needle 24 lowers to protrude from the coating liquid container 21. Then, as shown in (C), the liquid material 100 is applied to the object to be applied 5, and then, as shown in (D), the coating needle 24 rises.

In FIG. 9, the coating liquid container 21 does not descend, so the protrusion amount p of the coating needle 24 needs to be increased compared to the present embodiment in FIG. 8. However, if the protrusion amount p of the coating needle 24 becomes large (for example, 15 mm), the following problems arise.

First, when the coating needle 24 rises after the application of the liquid material 100 in FIG. 9D, air bubbles may be mixed into the liquid material 100 in the coating liquid container 21. This is due to the following reason. As shown in FIG. 9B and FIG. 9C, the liquid material 100 is unevenly attached to the part of the coating needle 24 that is exposed when it descends. In other words, on the outer periphery of the coating needle 24, areas with and without the liquid material 100 attached appear in a disorderly alternating manner in the extension direction. Such uneven attachment is caused by the liquid material 100 being pulled by the coating needle 24 when the coating needle 24 descends, resulting in a gap between the coating needle 24 and the coating liquid container 21 in the area close to the through hole 22. In FIG. 9D, where the part of the side of the coating needle 24 to which the liquid material 100 does not adhere returns to the coating liquid container 21, air bubbles are likely to be mixed into the liquid material 100 in the coating liquid container 21. The number of alternating regions with and without the liquid material 100 increases as the protrusion amount p of the application needle 24 increases. Therefore, the greater the protrusion amount p, the greater the possibility of air bubbles being mixed in.

Furthermore, the non-uniform adhesion area of the liquid material 100 described above results in large variations in the diameter of the liquid material 100 applied to the object 5. Here, the application diameter means the maximum dimension of the applied liquid material 100 in a planar view (for example, the length of the major axis if the shape is elliptical), in other words, the diameter of an imaginary circle circumscribed by the liquid material 100. This can cause a problem in that the planar shape of the pattern of the liquid material 100 formed is not stable.

On the other hand, if the protrusion amount p in FIG. 9 is made extremely short (for example, less than 1 mm), another problem may occur as follows. FIG. 10 is a schematic diagram showing the coating process when the protrusion amount of the coating needle is normal. FIG. 11 is a schematic diagram showing the coating process when the protrusion amount of the coating needle is extremely short, for comparison with FIG. 10. In FIG. 10 and FIG. 11, the process proceeds in the order of (A), (B), and (C), where (A) shows the waiting state before coating, (B) shows the coating state, and (C) shows the retreated state after coating. By comparing FIG. 10 and FIG. 11, in the case of FIG. 11 where the protrusion amount of the coating needle 24 from the through hole 22 at the bottom of the coating liquid container 21 is short, the coating diameter of the liquid material 100 transferred to the coating object becomes excessively large compared to FIG. 10 where the protrusion amount is normal. This is because in FIG. 11, as soon as the tip 23 of the application needle 24 is exposed from the through hole 22, it immediately reaches the object to be applied 5, and the amount of liquid material 100 adhering to the tip 23 at the time of exposure from the through hole 22 becomes excessively large.

In consideration of the problems of the comparative example, the liquid material application unit 4 of this embodiment includes a coating needle 24 and a coating liquid container 21. The coating needle 24 applies the liquid material 100. The coating liquid container 21 holds the liquid material 100 inside, and has a through hole 22 formed at the bottom through which the coating needle 24 penetrates. The coating liquid container 21 includes a connecting portion 25 and a needle moving portion 26. The connecting portion 25 extends along a horizontal direction intersecting with the extending direction of the coating needle 24. The needle moving portion 26 extends from the connecting portion 25 toward the through hole 22 along the up-down direction, which is the extending direction of the coating needle 24. The protrusion amount P by which the coating needle 24 can protrude from the through hole 22 of the coating liquid container 21 along the up-down direction is 1 mm or more and 3 mm or less. The first width W1 in the horizontal direction of the needle moving portion 26 is 5 mm or less. The length that the needle movement part 26 extends in the vertical direction from the joint part 25 to the through hole 22 is 5 mm or more.

The liquid material application unit 4 and the liquid material application device 200 including the same can drastically reduce the intrusion of air bubbles into the liquid material 100 in the application liquid container 21 by making the protrusion amount appropriately short, i.e., 3 mm or less. This reduces the number of alternating areas on the side of the application needle 24 where the liquid material 100 is attached and where it is not attached, as shown in FIG. 9(D). This reduces the possibility that air generated by the gap between the area where the liquid material 100 is not attached and the wall of the through-hole 22 will be caught in the application liquid container 21 when the application needle 24 rises. This provides the above-mentioned effect.

In addition, by keeping the protrusion length appropriately short, at 3 mm or less, the variation in the application diameter of the liquid material 100 can be reduced, and a pattern with a stable application diameter can be transferred. The number of alternating areas on the side of the application needle 24 where the liquid material 100 is attached and where it is not attached is reduced in FIG. 9(D). This is because the effect of unevenly applied liquid material 100 on the pattern of the transferred liquid material 100 is reduced.

In addition, by keeping the protrusion length appropriately short, at 3 mm or less, the application time can be shortened. This is because a short protrusion length requires less time for the application needle 24 to protrude (lower) and retract (raise) compared to a longer protrusion length. This allows for quick and stable application of even highly volatile liquid material 100.

In addition, by keeping the protrusion length appropriately short, at 3 mm or less, loss of liquid material 100 can be reduced. Liquid material 100 that adheres unevenly to the side of the application needle 24 is difficult to use for subsequent transfer to the application target object 5. Therefore, by shortening the protrusion length and reducing the amount of liquid material 100 that adheres unevenly, it is possible to reduce the amount of liquid material 100 that is not used for transfer.

The effect of appropriately shortening the protrusion amount can be achieved by making the first width of the needle moving part 26 in the horizontal direction 5 mm or less, and making the length of the needle moving part 26 extending in the vertical direction from the joint part 25 5 mm or more. In this way, when the coating object 5 has a groove shape or a concave shape, the needle moving part 26 can be arranged so as to be surrounded by the side part, and the coating liquid container 21 can be brought close to the bottom part of the coating object 5. In other words, at least a part of the needle moving part 26 is inserted so as to fit into the side part of the groove shape or the like of the coating object 5. This allows the distance between the bottom part of the coating object 5 and the lowest part of the needle moving part 26 to be a length suitable for coating. It is more preferable that the vertical length T of the needle moving part 26 is 5 mm or more as described above. However, the length T needs to be at least longer than the dimension obtained by subtracting the protrusion amount P (for example, 3 mm) of the coating needle 24 from the vertical depth of the side part of the coating object 5. This can achieve the above effect.

In addition, by making the protrusion length appropriately long, at least 1 mm, the amount of liquid material 100 adhering to the tip 23 of the application needle 24 can be reduced, making it possible to apply fine patterns.

The features of the shape, dimensions, etc. of the coating liquid container 21 of the liquid material coating unit 4 of this embodiment described above are particularly effective when transferring liquid material 100 to a bottom surface portion located deep inside the side portion of a coating target 5 having a groove or concave shape.

In the liquid material application unit 4, it is preferable that the first width W1 is 5 times or less than the second width W2 in the horizontal direction of the portion of the application needle 24 that extends in the vertical direction. In this way, the same effect as above can be obtained.

The liquid material application method of this embodiment includes the following steps. The liquid material 100 is held inside a coating liquid container 21 having a through hole 22 formed in the bottom, and the coating liquid container 21 is opposed to the object 5 to which the liquid material 100 is to be applied with the coating liquid 100 while the tip 23 of the coating needle 24 is immersed in the liquid material 100. The coating liquid container 21 is brought close to the object 5 to be applied. The coating needle 24 is moved along the extension direction of the coating needle 24 to apply the liquid material 100 to the object 5 to be applied. In the coating step, the amount of protrusion P that the coating needle 24 can protrude from the through hole 22 of the coating liquid container 21 along the extension direction is 1 mm or more and 3 mm or less. In the approaching step, the coating liquid container 21 is positioned so that at least a part of it is surrounded by the object 5 to be applied. In this manner, the same effect as above can be obtained.

In the above liquid material application method, the liquid material 100 is preferably a liquid in which fine particles are suspended. Since the liquid material 100 containing fine particles has poor elasticity and is easily torn, it is prone to uneven adhesion to the side of the application needle 24 as shown in (B) to (D) of Figure 9. However, when using such a liquid material 100, the liquid material application method of this embodiment is particularly effective, and the same effects as those described above can be obtained.

In the above liquid material application method, the viscosity of the liquid material is preferably 13.10 Pa·s or less. If the viscosity of the liquid material 100 is excessively high, a large amount of liquid material 100 adhered to the tip 23 of the application needle 24 makes it difficult to separate the liquid material 100 between the application needle 24 and the application target 5 when it starts to rise after application. By lowering the viscosity as described above, such problems can be suppressed.

A test was conducted to compare the rate of air bubbles by changing the above-mentioned protrusion amount P. An investigation was conducted when the protrusion amount P of the coating needle 24 from the coating liquid container 21 was set to 15 mm and 3 mm. The liquid material 100 was a polymer solution. Three types of liquid material 100 were used: one with a viscosity of 0.45 Pa·s (referred to as "A"), one with a viscosity of 1.95 Pa·s (referred to as "B"), and one with a viscosity of 13.10 Pa·s (referred to as "C"). 48 samples of each were prepared, and the same test was conducted for each.

The test results for a coating needle 24 that does not have a tapered tip 23 and has a circular cross section intersecting the extension direction with a first width W1 of 1000 μm (hereinafter referred to as the "first coating needle") are shown in Table 1 below.

The test results for the coating needle 24, which is circular with a first width W1 of 1000 μm except for the tip 23 as described above, and has a tapered shape at the tip 23, with the cross section intersecting the extension direction at the bottom being circular with an outer diameter (corresponding to W1 above) of 800 μm (hereinafter referred to as the "second coating needle"), are shown in Table 2 below.

From Tables 1 and 2, it can be seen that, regardless of the type of application needle 24, when the protrusion amount P was 15 mm, there was a high probability of air bubbles being mixed in, whereas when the protrusion amount P was 3 mm, the inclusion of air bubbles was completely suppressed. As the viscosity of the liquid material 100 increased, the rate of air bubbles mixed in when the protrusion amount was 15 mm increased. On the other hand, when the protrusion amount was 3 mm, no air bubbles were mixed in, even in the example with the highest viscosity of 13.10 Pa·s. From this, it can be seen that if the viscosity was 13.10 Pa·s or less, the inclusion of air bubbles could be completely suppressed by setting the protrusion amount to 3 mm.

Furthermore, in the above test, the variation in the coating diameter of the liquid material 100 was investigated. Figure 12 is a graph showing the test results of the variation in the coating diameter when the protrusion amount is 3 mm. Figure 13 is a graph showing the test results of the variation in the coating diameter when the protrusion amount is 15 mm. In each figure, "Φ800 μm" indicates the results for the second coating needle, and "Φ1000 μm" indicates the results for the first coating needle. The calculation results of the coefficient of variation (3σ/Ave.) obtained from Figures 12 and 13 are shown in Table 3 below.

Referring to Figures 12 and 13 and Table 3, the following results were obtained. When the protrusion amount was 15 mm, there was variation in the coefficient of variation between different viscosities of the liquid material 100, i.e., A, B, and C, and there was also variation between the same viscosity. Furthermore, when the protrusion amount was 15 mm, the absolute value of the coefficient of variation was large. In contrast, when the protrusion amount was 3 mm, there was less variation in the coefficient of variation between different viscosities of the liquid material 100, i.e., A, B, and C, and there was also less variation between the same viscosity. Furthermore, there was less variation in the coefficient of variation when the protrusion amount was 3 mm. Note that no clear difference was observed between the cases where the first application needle was used and the second application needle was used.

From the above, by setting the protrusion amount to 3 mm, the variation in the application diameter was reduced compared to when the protrusion amount was 15 mm. This can be presumed to be because by setting the protrusion amount to 3 mm, the variation in the application amount of liquid material 100 on the side of the application needle 24 is reduced compared to when the protrusion amount was 15 mm, making it possible to stably apply the liquid material 100.

As described above, by reducing the amount of protrusion P (see FIG. 2) of the coating needle 24 from the through hole 22 of the coating liquid container 21 during the coating process, it is possible to prevent air bubbles from being mixed into the liquid material 100 in the coating liquid container 21. This allows for a stable supply of patterns with fine coating diameters.

However, if the amount of liquid material 100 in the coating liquid container 21 is small, air bubbles may be mixed into the liquid material 100 in the coating liquid container 21. This is presumably because, when the coating needle 24 rises and is stored in the coating liquid container 21, the tip of the coating needle 24 (the lowermost part of the tip 23) moves away from the liquid surface of the liquid material 100 in the coating liquid container 21, and when the coating needle 24 descends again, the tip of the coating needle 24 bites in air. For this reason, even at the early stage of the coating process when the amount of liquid material 100 in the coating liquid container 21 has not decreased much, if air bubbles are mixed into the liquid material 100, the liquid material 100 cannot be applied sufficiently, and the efficiency of use of the liquid material 100 may decrease. This embodiment describes the results of an investigation into a method for adjusting the configuration of the liquid material coating unit to address the cause of this air bubble mixing. In the following, unless otherwise specified, the liquid level of the liquid material 100 refers to the liquid level on the vertically upper side of the liquid material 100 (the topmost part of the liquid material 100).

Using the same liquid material "C" with a viscosity of 13.10 Pa·s as in Example 1, the presence or absence of air bubbles was investigated while changing the initial vertical position of the coating needle 24 relative to the vertical position of the liquid surface of the liquid material 100 in the coating liquid container 21. The results of the investigation are shown in Table 4 below. Note that the initial position of the coating needle 24 refers to the initial vertical position of the coating needle 24 before the coating needle 24 begins its downward movement (initial state) to perform the coating process.

From Table 4, it was found that when the tip of the coating needle 24 is positioned above the liquid surface of the liquid material 100 in the initial state, i.e., when the coating needle 24 is not immersed in the liquid material 100 at all, air bubbles are likely to occur in the liquid material 100. For this reason, it is necessary to set the initial position of the coating needle 24 so that the tip of the coating needle 24 is lowered as far below the liquid surface of the liquid material 100 as possible. Adjusting the initial position of the coating needle 24 is particularly important when the amount of liquid material 100 is small and the liquid surface is descending.

Figure 14 is a schematic diagram showing the initial vertical position of the coating needle in the coating liquid container. Referring to Figure 14, the coating needle 24 includes a tip 23 that is inclined as shown in Figure 14 by tapering or the like, and a constant width region 24a other than the tip 23. The constant width region 24a is located above the tip 23, and is a region in which the maximum width of the periphery remains almost constant even when moved in the vertical direction. The maximum width of the periphery of the constant width region 24a is W2.

The inner wall 21a of the coating liquid container 21 has a tapered shape in which the dimension in the left-right direction in the figure, i.e., the area of the cross section along the horizontal direction, is smaller at the lower side than at the upper side. The initial position of the coating needle 24 is the vertical position of the tip of the coating needle 24 with respect to the lowermost part O of the through-hole 22 of the coating liquid container 21, and is represented by a distance _P0 . The distance _P0 is set to be larger than the vertical length t of the through-hole 22 at the lower part of the coating liquid container 21. When the coating needle 24 is stored in the coating liquid container 21, the liquid material 100 flows around and into the area adjacent to the tip of the coating needle 24 (the area immediately below the tip of the coating needle 24) in the coating liquid container 21.

However, if the vertical distance _P0 between the bottom of the through hole 22 and the tip of the coating needle 24 at the initial position of the coating needle 24 is short, the liquid material 100 is less likely to flow into the area adjacent to the tip of the coating needle 24, and the time required for the flow becomes longer. If the time required for the flow becomes longer, the so-called "coating interval" is set longer, and the tact time of the process in which the coating needle 24 applies the liquid material 100 becomes longer. For this reason, the initial position of the coating needle 24, that is, the above-mentioned distance _P0 , is empirically set to be greater than the vertical length t of the through hole 22. However, the design criteria for the distance _P0 were not clear. Therefore, in this embodiment, a method was verified in which the initial position (distance _P0 ) of the coating needle 24 is shortened as much as possible by controlling the porosity at the "gap position" to enable the tip of the coating needle 24 to be lowered as much as possible below the liquid level of the liquid material 100. That is, a method was verified in which the initial position of the lowest part of tip 23 of coating needle 24 is set to a position where tip 23 is placed in liquid material 100 and is covered by liquid material 100. Below, a case where distance _P0 is smaller than t will also be considered.

FIG. 15 is a schematic diagram for explaining the gap position. Referring to FIG. 15, the gap position P ₁ is a position where the distance between the coating needle 24 and the inner wall of the coating liquid container 21, particularly the through hole 22, is minimum in the left-right direction (horizontal direction) of FIG. 15 intersecting the extending direction of the coating needle 24 among the initial positions in the up-down direction of the coating needle 24 in the initial state. Here, the coating needle 24 at the gap position P ₁ may have a tip portion 23 having a tapered outer periphery. The gap position P ₁ is determined in a region above the region where the C surface 27 is formed in FIG. 15, at the bottom of the through hole 22. Usually, as shown in FIG. 15, the left-right distance between the outer periphery of the tip portion 23 of the coating needle 24 and the wall surface of the through hole 22 surrounding it from the side is relatively smaller than the left-right distance in other regions. In this case, the gap position P ₁ is the top of the through hole 22. This is because the outer circumference of the coating needle 24 at the tip 23 gradually increases from the tip upward along the tapered shape, and the diameter Td of the coating needle 24 at the gap position _P1 is larger than the diameter Pd of the tip of the coating needle 24 (however, the diameter Td is smaller than the diameter Hd of the through hole 22). In the region above the through hole 22, the left-right dimension of the inner wall 21a of the coating liquid container 21 is significantly larger than the left-right dimension of the through hole 22. Therefore, in the region above the through hole 22, the distance between the outer circumference of the tip 23 and the inner wall 21a of the coating liquid container 21 is not minimum. Therefore, the position where the diameter Td is maximum right next to the through hole 22 is usually the top of the through hole 22. In FIG. 15, the tip 23 is located above and below the top of the through hole 22, but it is also assumed that the constant width region 24a is located at that position.

FIG. 16 is a schematic cross-sectional view taken along line XVI-XVI in FIG. 15. That is, FIG. 16 shows the cross-sectional aspect at the gap position P ₁ in the vertical direction. Thus, FIG. 16 shows a schematic view for explaining the void ratio. Referring to FIG. 16, the void ratio is the ratio of the area of the gap region excluding the _portion where the coating needle (tip portion 23) is disposed to the area of the region surrounded by the inner wall 21a (through hole 22) of the coating liquid container 21 on a plane (the paper surface showing FIG. 16) along the horizontal direction at the gap position P 1. In other words, the void ratio is the ratio of the area of the gap 28 between the outermost portion of the tip portion 23 and the inner wall (through hole 22) to the area of the inner region of the portion (through hole 22) in FIG. 16 corresponding to the inner wall 21a in FIG. 15.

In this example, the same liquid material "C" with a viscosity of 13.10 Pa·s as above was used to investigate the effect on the coating interval when the porosity was changed. The coating interval is the time from the moment when the coating needle 24 finishes rising after coating to the moment immediately before the coating needle 24 starts to descend to coat again. The coating interval was determined by comparing the first coating diameter of the pattern coated in the first coating process with the second coating diameter of the pattern coated in the second coating process immediately thereafter, and by determining the time required for the difference between them to be within 5% of the value of the first coating diameter.

Normally, if the coating interval is shorter than the time it takes for the liquid material 100 to flow into the area adjacent to and directly below the tip of the coating needle 24 in the coating liquid container 21, the coating diameter tends to be smaller. The coating interval when the porosity is 80% was set as the reference value 1, and the change in coating interval when the porosity is changed was calculated. The calculation results are shown in Table 5 below. Note that in Table 5, when the rate of change in coating interval for a porosity of 80% is within 5% (i.e., the coating interval is 0.95 or more and 1.05 or less), the coating interval is recorded as 1 (no change).

As shown in Table 5, the smaller the porosity, the longer the application interval. In other words, a smaller porosity indicates that the application needle 24 is lowered further. This is because, when the tip 23 is at the same height as the top of the through-hole 22, the diameter Td of the application needle 24 at the same height as the top of the through-hole 22 becomes larger when the application needle 24 is lowered. For this reason, by lowering the initial position of the application needle 24 and setting the porosity to, for example, 43% or less, the inclusion of air bubbles can be suppressed as shown in Table 4. This is because, when the porosity is 43% or less, the tip of the application needle 24 is positioned relatively lower in the liquid material 100 at the initial position and is sufficiently immersed in the liquid material 100 compared to when the porosity is 80%. However, in this case, the application interval becomes longer as shown in Table 5, and the takt time becomes longer, which reduces the efficiency of use of the liquid material.

Therefore, according to Table 5, the coating liquid container 21 is opposed to the coating target 5 of the liquid material 100 before the coating process (as shown in FIG. 8A) so that the coating interval is within a range that does not change from the reference value. At this time, it is more preferable to determine the initial position of the coating needle 24 so that the porosity is the smallest within the range of porosity in which the coating interval does not change from the reference value (even if it changes, it is within 5% of the reference value of the coating interval when the porosity is 80%). Specifically, in the process of opposing as shown in FIG. 8A, it is preferable to determine the initial position of the coating needle 24 so that it is at a position where the porosity is 62% or more (60% or more). If the initial position of the coating needle 24 is lowered to a position where the porosity is, for example, 62% (60%), the coating needle 24 is located lower than when the initial position of the coating needle 24 is set to a position where the porosity is 80%. Therefore, if the initial position of the application needle 24 is lowered to a position where the porosity is 62% (60%), the inclusion of air bubbles can be suppressed according to Table 4, and the increase in the application interval can be suppressed according to Table 5, which is more preferable. Therefore, if the porosity is set to 62% (60%), the inclusion of air bubbles can be suppressed while the extension of the takt time of the application process can be suppressed. In this way, by adopting an adjustment method that minimizes the application interval compared to the conventional empirical method, the use efficiency of the liquid material 100 is improved and the application interval can be minimized.

When the tip diameter Pd of the coating needle 24 is large and a highly viscous liquid material 100 is used, air bubbles can be prevented by placing the coating needle 24 in the preferred initial position found in this embodiment, but there is a risk of the coating interval becoming longer. In such a case, design factors such as the internal shape of the coating liquid container 21, the diameter Hd of the through hole 22 of the coating liquid container 21, and the shape of the coating needle 24 may be optimized. This may expand the space near the tip of the coating needle 24 in the initial position, making it easier for the liquid material 100 to flow into the space near the tip of the coating needle 24. In this way, the effect of shortening the takt time of the coating process without introducing air bubbles is enhanced.

In the second embodiment, a method for preventing an increase in the coating interval is shown, focusing on the gap position _P1 . However, if the coating interval is shortened, air bubbles may be mixed into the liquid material 100 in the coating liquid container 21. FIG. 17 is a schematic diagram showing the mechanism of air bubble mixing caused by the coating interval. FIG. 17 shows the change over time in the order of (A), (B), and (C). Referring to FIG. 17, when the coating needle 24 is stored in the coating liquid container 21, the liquid material 100 flows into the area adjacent to the tip of the coating needle 24 in the coating liquid container 21. However, if the coating interval is short, the coating needle 24 enters the coating liquid container 21 without the area adjacent to the tip of the coating needle 24 being sufficiently filled with the liquid material 100. At this time, the air in the area adjacent to the tip of the coating needle 24 that is not sufficiently filled with the liquid material 100 is drawn into the liquid material 100. When such a problem occurs, it is considered preferable to increase the coating interval.

Figure 18 is a flow chart showing a liquid material application method in Example 3. Referring to Figure 18, in this example, the process of the application needle 24 applying the liquid material 100 is performed multiple times. In other words, the application process includes a first application process (S10) in which the application needle 24 applies the liquid material 100, and a second application process (S20) in which the application needle 24 applies the liquid material 100 again immediately thereafter.

Between the first coating step (S10) and the second coating step (S20), the coating needle 24 moves upward away from the coating target 5 as shown in FIG. 8(E) (S11). As a result, the entire coating needle 24, including its tip, is stored inside the coating liquid container 21. At this time or immediately after this, the coating liquid container 21 may rise. Immediately after this, a horizontal movement step is performed in which the coating needle 24 moves relatively in the horizontal direction to a position where the liquid material 100 is to be applied in the second coating step (S12). In other words, the coating target 5 is moved, for example, by the X-axis table 1 and the Y-axis table 2 (see FIG. 1) so that the coating target 5 to be next coated by the coating needle 24 is directly below the liquid material coating unit 4. Alternatively, the coating needle 24 may move in a direction along the XY plane to directly above the position of the coating target 5 to be next coated. As a result, the coating liquid container 21 faces the coating target 5 of the liquid material 100.

Furthermore, between the first coating step (S10) and the second coating step (S20), a step is provided in which the coating needle 24 waits in the coating liquid container 21 (S13). The time during which the coating needle 24 waits in the coating liquid container 21 is, specifically, the time during which the stage such as the X-axis table 1 and the coating liquid container 21 do not move, and the coating needle 24 does not rise or fall relative to the coating liquid container 21, and the coating needle 24 is in a stationary state in the coating liquid container 21. In this embodiment, such a waiting time for the coating needle 24 is provided in the step (S13). After that, the coating liquid container 21 is brought close to the coating object 5 (S14). That is, for example, the coating liquid container 21 descends as shown in FIG. 8 (B). After that, the coating needle 24 descends relative to the coating liquid container 21 as shown in FIG. 8 (C), and the tip 23 of the coating needle 24 comes into contact with the coating object 5 as shown in FIG. 8 (D). The second coating process (S20) is performed as shown in Figures 8(C) and (D).

As described above, this embodiment is characterized in that, in addition to steps (S11), (S12), and (S14), a step (S13) in which the coating needle 24 waits in the coating liquid container 21 is provided between the first coating step (S10) and the second coating step (S20). Step (S13) may be performed either before or after the horizontal movement step (S12). The coating interval in this embodiment is the coating interval in Example 2 plus the time for step (S13) in which the coating needle 24 waits in the coating liquid container 21. In other words, the coating interval in this embodiment is the time from the moment when the coating needle 24, having finished coating in the first coating step (S10), is entirely stored in the coating liquid container 21 and its ascent ends, to the moment when (the coating liquid container 21 is raised), the horizontal movement step (S12), the waiting step (S13), and the descent of the coating liquid container 21 (S14) end, and just before the descent of the coating liquid container 24 in the second coating step (S20) begins.

The adjustment method of this embodiment is particularly effective when the horizontal distance (pitch) between the application position in the first application process (S10) and the application position in the second application process (S20) is short. The adjustment method of this embodiment is also particularly effective when the movement time of stages such as the X-axis table 1 and Y-axis table 2 in the horizontal movement process (S12) is short.

Next, the experimental content and results for this embodiment will be described. The same liquid materials as "A" with a viscosity of 0.45 Pa·s, "B" with a viscosity of 1.95 Pa·s, and "C" with a viscosity of 13.10 Pa·s were used to change the application interval and investigate the rate of air bubble inclusion. The change in application interval was adjusted by the presence or absence of a step (S13) in which the application needle 24 waits in the application liquid container 21 and by changing the time for this step. The test results are shown in Table 6 below.

As shown in Table 6, in the case of A with low viscosity, even when the application interval was short, 1 second (i.e., the step (S13) of making the application needle 24 wait in the application liquid container 21 was not performed), no air bubbles were mixed in. However, in the case of a short application interval of 1 second, when B with high viscosity was used, the air bubble mixing rate was higher than when A was used. Furthermore, when C with even higher viscosity was used, the air bubble mixing rate was even higher than when B was used. It can be assumed that A has low viscosity, so the liquid material 100 flows easily, and the liquid material 100 fills the area directly below the tip of the application needle 24 immediately after the application needle 24 is stored in the application liquid container 21, so no air bubbles were mixed in. However, even when B and C with high viscosity were used, the air bubble mixing rate was reduced by lengthening the application interval and providing the waiting step (S13). When the application interval was 3 seconds, the air bubble mixing rate was 13% for C with the highest viscosity, whereas when the application interval was 5 seconds, the air bubble mixing rate was 0% even for C. When the application interval was 3 seconds, the waiting time of the application needle 24 was 2 seconds. When the application interval was 5 seconds, the waiting time of the application needle 24 was 4 seconds. Therefore, it was found that the higher the viscosity, the longer the application interval (the waiting time of the application needle 24 in step (S13)) is required to prevent air bubbles from being mixed in.

Note that the polymer solution of liquid material 100 exhibits complex flow characteristics depending on the type, and even with the same viscosity, the fluid behavior differs depending on whether it is thixotropic and spinnable. When setting the application interval, it is preferable to take into full consideration the flow characteristics of the liquid material 100 used and set the application interval based on the test results in Table 6.

The examples included in the above-described embodiments and the features described in each example may be combined as appropriate within the scope of technical compatibility. For example, the features derived in example 2 may be combined with the features derived in example 3. The features included in this embodiment may be applied to each of examples 1 to 3.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 X-axis table, 2 Y-axis table, 3 Z-axis table, 4 Liquid material application unit, 5 Coating object, 6 Observation optical system, 7 CCD camera, 8 Operation panel, 9 Monitor, 10 Control computer, 11 Control unit, 12 Base, 21 Coating liquid container, 21a Inner wall, 22 Through hole, 23 Tip, 24 Coating needle, 24a Fixed width area, 25 Joint, 26 Needle moving part, 27 C surface, 28 Gap, 100 Liquid material, 102 Coating needle holder, 104 Coating needle holder storage part, 106 Coating needle holder fixing part, 108 Movable part, 110 Connecting shaft, 112 Connecting plate, 114 Eccentric shaft, 116 Eccentric plate, 118 Origin sensor, 120 Servo motor, 121 Motor drive part, 122, 124 Bearing, 126 spring, 128, 128A, 128B fixed pin, 130 linear motion mechanism, 132 linear guide, 143 cam, 145 cam connecting plate, 161 cam surface, 162 upper end flat area, 163 lower end flat area, 200 liquid material application device.

Claims (9)

an application needle for applying a liquid material;
a coating liquid container for holding the liquid material therein and having a through hole formed in a bottom portion through which the coating needle passes;
the coating liquid container includes a connecting portion extending along a horizontal direction intersecting an extension direction of the coating needle, and a needle moving portion extending from the connecting portion toward the through hole along a vertical direction that is the extension direction of the coating needle,
a protrusion amount of the coating needle from the through hole of the coating liquid container along the up-down direction is 1 mm or more and 3 mm or less,
The first width of the needle moving portion in the horizontal direction is 5 mm or less,
A liquid material application unit, wherein the length of the needle moving portion extending in the vertical direction from the connecting portion to the through hole is 5 mm or more. The liquid material application unit according to claim 1, wherein the first width is 5 times or less than the second width in the horizontal direction of the portion of the application needle that extends in the vertical direction. A liquid material application device comprising the liquid material application unit according to claim 1 or 2. a step of holding a liquid material inside a coating liquid container having a through hole formed in a bottom portion, and facing the coating liquid container to an object to be coated with the liquid material while a tip portion of a coating needle is immersed in the liquid material;
bringing the coating liquid container close to the object to be coated;
a step of moving the application needle along an extension direction of the application needle to apply the liquid material to the application target,
In the coating step, a protrusion amount of the coating needle that can protrude from the through hole of the coating liquid container along the extension direction is 1 mm or more and 3 mm or less,
A liquid material applying method, wherein in the step of bringing the application liquid container closer to the object to be applied, the application liquid container is positioned so that at least a portion of the application liquid container is surrounded by the object to be applied. a void ratio is defined that indicates a ratio of an area of a region excluding a portion where the coating needle is disposed to an area of a region surrounded by the inner wall on a plane along the horizontal direction at a gap position where a distance between the coating needle and the inner wall of the coating liquid container in a horizontal direction intersecting an extending direction of the coating needle is minimum;
The liquid material applying method according to claim 4 , wherein in the opposing step, the application needle is positioned such that a position of the tip of the application needle in the extension direction is a position where the porosity is 60% or more. The liquid material application method according to claim 4 or 5, wherein the viscosity of the liquid material is 13.10 Pa·s or less. The liquid material application method according to any one of claims 4 to 6, wherein in the application step, the application needle repeats movement toward the object to be applied and movement away from the object to be applied along the extension direction 9 times or less per second. the applying step includes a first applying step in which the application needle applies the liquid material, and a second applying step in which the application needle applies the liquid material immediately after the first applying step,
The liquid material application method according to any one of claims 4 to 7, wherein between the first application step and the second application step, there are performed a horizontal movement step in which the application needle relatively moves in a horizontal direction intersecting the extension direction to a position to which the liquid material is to be applied in the second application step, a step in which the application needle waits in the application liquid container, and the approaching step. The liquid material application method according to any one of claims 4 to 8, wherein the liquid material is a liquid in which fine particles are suspended.

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