JP2005270929A - Droplet arranging method and droplet arranging apparatus - Google Patents

Abstract

Disclosed is a droplet arranging method and a droplet arranging apparatus which are accurate not only in the diameter of droplets at the time of jetting but also in the diameter after landing on a substrate surface.
In a droplet arrangement method for arranging droplets 13 on the surface of a substrate 4 by ejecting the droplets 12 to a desired portion of the substrate 4, the atmosphere around the substrate 4 is replaced by an inert gas from the atmosphere. A change in wettability between the surface of the substrate 4 and the droplet 12 is prevented. The droplet arrangement device includes a container 1 that holds a liquid 11, an acoustic generator 9 that generates acoustic energy, and an acoustic lens 8 that focuses the acoustic energy generated by the acoustic generator 9 onto the liquid 11 in the container 1. And holding means 5 for holding the substrate 4 to which the droplets 12 ejected from the surface of the liquid 11 adhere, and means for controlling the atmosphere around the substrate 4.
[Selection] Figure 1

Description

  The present invention relates to a droplet arranging method for arranging droplets on a surface of a substrate by ejecting the droplets onto a desired portion of the substrate, a fine particle array obtained by the method, and a droplet arranging apparatus for carrying out the method About.

  As a method of arranging droplets or fine particles on the surface of a substrate, a method of applying droplets to a desired site on the substrate by applying a printing ink jet technique is known. Above all, the piezoelectric element generates acoustic energy because it is easy to reduce the diameter of the droplets, the nozzles are not clogged, foreign matters are not mixed due to nozzle wear, and the flying direction of the droplets does not change. Development of a nozzleless ink jet technique for focusing the energy in the vicinity of the liquid surface by a lens and ejecting droplets from the liquid surface is underway.

  As a technique for arranging droplets and fine particles on the substrate surface by the nozzleless ink jet technology, one used for manufacturing a circuit board (for example, see Patent Document 1), one used for manufacturing a color filter (for example, Patent Document 2), biological Those used for detection of a specimen (for example, see Patent Documents 3 and 4) and those used for manufacturing a microlens (for example, see Patent Document 5) are known.

  In addition, a technique that is limited to image printing applications is also known (for example, see Patent Document 6) in which ink is once ejected onto an image carrier having a photocatalyst and then transferred from the carrier to paper. It has been.

JP-A-9-57963 JP-A-7-314666 Japanese Patent Laid-Open No. 2002-228672 JP 2003-121440 A JP 2003-90904 A JP-A-11-268255

  The nozzleless inkjet technology, which is the premise of these, is being developed with a focus on how to control the droplet diameter at the time of ejection or how to make the droplet land at an accurate position. . However, for example, when drawing circuit wiring using droplets, it is not the droplet diameter at the time of ejection that defines the line width, but the diameter of the droplet after landing on the substrate surface. By controlling only the diameter and landing position, the original purpose of drawing accurate circuit wiring cannot be achieved.

Although only Patent Document 6 is an invention that focuses on the landing state of a droplet, it cannot be landed on the substrate paper itself, and can therefore be used as a technique for directly arranging the droplet on the substrate surface. Absent.
For this reason, when arranging the droplets on the surface of the substrate, there is a demand for a technique that can prevent a change in the diameter of the landed droplets and obtain a desired arrangement state.

In view of the above problems, the inventors have completed the following invention.
The first invention is a droplet arrangement method in which droplets are arranged on a substrate surface by ejecting the droplets onto a desired portion of the substrate, and the characteristic configuration thereof is a change in wettability between the substrate surface and the droplets over time. It is a point to prevent.
Thus, by preventing the change in the wettability between the substrate surface and the droplets with time, it is possible to prevent a change in diameter due to a change in the wettability of the landed droplets. As a result, a desired arrangement state of the droplets that have landed on the substrate surface can be obtained.

The second invention is that, in the first invention, the atmosphere around the substrate is replaced with an inert gas from the atmosphere in order to prevent the change in wettability with time.
By doing so, it is possible to prevent the adsorbed substance contained in the atmosphere from adhering to the surface of the substrate, so that an effective method for preventing the change in wettability between the surface of the substrate and the droplets with time can be obtained.

The third invention is that, in the first or second invention, the substrate surface is treated so as to have a predetermined wettability, and then droplets are ejected onto the substrate surface.
If the surface of the substrate is treated in advance so as to have a predetermined wettability, the spread of the landed droplet diameter due to the wettability can be controlled in advance. A desired arrangement in which the droplet diameter landed on the substrate surface is accurate can be obtained.

According to a fourth invention, in any one of the first to third inventions, the droplets are made of a dispersion liquid in which fine particles are dispersed.
By using such a dispersion, the fine particles can be arranged on the substrate surface in a desired arrangement state by the droplet arrangement method of the present invention.

  The fifth invention is a fine particle array obtained by removing liquid components from the droplets on the substrate surface arranged by the droplet arranging method of the fourth invention.

According to a sixth aspect of the invention, there is provided a container that holds a liquid, an acoustic generator that generates acoustic energy, an acoustic lens that focuses the acoustic energy generated by the acoustic generator onto the liquid in the container, and the liquid surface that is ejected from the liquid surface. A droplet arranging device comprising a holding means for holding the substrate to which the droplets adhere, and a means for controlling the atmosphere around the substrate.
With such an apparatus, droplets are ejected from the liquid surface in the container to the substrate surface by the focused acoustic energy, and the atmosphere around the substrate is controlled to change the wettability between the substrate surface and the droplets over time. Therefore, a desired array of droplets that have landed on the substrate surface can be obtained.

According to a seventh aspect of the invention, in the sixth aspect of the invention, the means for controlling the atmosphere around the substrate includes at least a case capable of accommodating the substrate therein, and a gas supplier for supplying an inert gas into the case. It is a droplet arrangement device.
In such an apparatus, the periphery of the substrate housed in the case can be surely replaced with an inert gas atmosphere. Specific means capable of preventing the adsorbent contained in the substrate from adhering to the substrate surface are provided.

According to an eighth aspect of the present invention, in the sixth aspect of the invention, the means for controlling the atmosphere around the base includes at least a case capable of housing the base and a means for maintaining the inside of the case in a reduced pressure or pressurized state. It is a droplet arrangement device.
With such an apparatus, it is possible to control the properties of the liquid, the drying speed of the landed droplets, or the wettability between the substrate surface and the droplets in a state different from the case where the inside of the case is under normal pressure. it can.

  In the present invention, not only the droplet diameter at the time of jetting and the landing position of the droplet on the substrate surface are controlled, but also the droplet diameter landed on the substrate surface due to the change in wettability between the substrate surface and the droplet. It is possible to provide a method and apparatus for preventing a change with time and obtaining a desired droplet arrangement state, thereby providing a substrate on which droplets or fine particles are accurately arranged.

Hereinafter, an embodiment of a droplet arranging method and apparatus according to the present invention will be described.
A droplet ejection mechanism in the droplet arraying apparatus of the present invention will be described with reference to FIG. The ejector 2 in this apparatus includes an acoustic generator 9 and an acoustic lens body 8. The liquid 11 ejected as the droplet 12 is held in the container 1, and the acoustic transmission medium 10 is filled and held by the cap 7 between the container 1 and the ejector 2.

  The acoustic generator 9 is composed of a piezoelectric element and an electrode, and generates acoustic energy by applying a high frequency voltage to the piezoelectric element. The acoustic generator 9 is joined to a cylindrical acoustic lens body 8. One end of the acoustic lens body 8 on the container 1 side is a concave lens, transmits acoustic energy generated by the acoustic generator 9 to the acoustic transmission medium 10, and focuses the energy near the liquid surface of the liquid 11. . The liquid 12 of the liquid 11 is ejected from the liquid surface by the energy transmitted from the acoustic transmission medium 10 through the bottom of the container 1.

  The liquid 11 is not particularly limited as long as it is liquid such as an aqueous solution, an organic solvent, a molten metal, or a dispersion in which fine particles are dispersed. The fine particles are not necessarily spherical, and may be indefinite or needle-shaped.

The acoustic generator 9 is not limited to a combination of a piezoelectric element and an electrode as long as it can generate acoustic energy.
The material of the acoustic lens body 8 is not particularly limited as long as the acoustic velocity is relatively high, but a silicon compound such as silicon or quartz is preferable. As an alternative to the concave lens, Fresnel elements may be provided at one end of the acoustic lens body 8.
The acoustic transmission medium 10 may be any of solid, liquid, and gas as long as it can transmit the acoustic energy generated by the ejector 2 from the container 1 to the liquid 11 without significant attenuation. Although not limited, water can be easily used.

If the ejector 2 transmits acoustic energy to the liquid 11 in a non-contact manner via the acoustic transmission medium 10 and the container 1, the type of the liquid droplet 12 can be easily changed by changing the type of the liquid 11 for each container 1. Can do.
Incidentally, if the ejector 2 is immersed in the liquid 11, the acoustic transmission medium 10 is not necessary. However, such a structure is not a problem if there is only one type of liquid 11 to be ejected. However, when a plurality of types of liquid 11 are to be ejected, the ejector 2 must be cleaned each time the type of the liquid 11 changes.

Furthermore, the schematic structure of the droplet arrangement device of the present invention is shown using FIG.
In addition to the container 1, the ejector 2, and the cap 7, the apparatus includes a base 4, a base support mechanism 5, an ejector support mechanism 3, a case 6, a gas supply device 14, and a pressure maintenance mechanism 15.

The substrate 4 is supported by the substrate support mechanism 5, and the ejector 2 is supported by the ejector support mechanism 3. In FIG. 1, the substrate support mechanism 5 and the ejector support mechanism 3 support the substrate 4 and the ejector 2 with the container 1 interposed therebetween. The support mechanism 5 and the ejector support mechanism 3 may have any structure.
Moreover, there is no restriction | limiting in particular in the shape and material of the base | substrate 4, What is necessary is just to select glass, a metal, ceramics, a plastics etc. as materials, such as flat shape, an array shape, and a spherical shape.

Obtaining a desired arrangement of droplets 12 on the surface of the substrate 4 means that one or a plurality of droplets 12 are adhered to the surface of the substrate 4, and when the landed droplets 13 exist as dots on the surface of the substrate 4. In addition to the case where the points are connected as a line.
In order to attach the plurality of droplets 12 to two-dimensionally or three-dimensionally different sites on the surface of the substrate 4, at least one of the substrate 4 or the ejector 2 must move two-dimensionally or three-dimensionally. For this reason, it is preferable that at least one of the base support mechanism 5 and the ejector support mechanism 3 has a function of moving the base 4 or the ejector 2 supported by the base support mechanism 5 or the ejector support mechanism 3 so that the base 4 and the ejector 2 are positioned in a desired positional relationship.

  The case 6 accommodates the container 1, the ejector 2, the cap 7, the base 4, the base support mechanism 5, and the ejector support mechanism 3 therein, and includes a gas inlet 6a and a gas outlet 6b. The case 6 can replace the atmosphere in the case with an inert gas by taking in the inert gas supplied from the gas supply device 14 from the gas inlet 6a and discharging it from the gas outlet 6b. Further, the pressure maintaining mechanism 15 discharges the atmosphere in the case 6 to the outside and maintains the inside of the case 6 in a decompressed state, or flows a pressurized gas from the outside into the case 6 to confine the gas. The pressure can be maintained. The gas supply device 14 and the pressure maintaining mechanism 15 may be provided with only one or both as required.

  Since the droplet 13 that has landed on the substrate 4 is dried from the end region, the diameter of the droplet 13 that has landed in the drying process hardly changes, and only the height of the droplet 13 with respect to the substrate 4 decreases. . Therefore, when arranging the droplets on the surface of the substrate 4, it is important to control the diameter of the landed droplet 13.

  The diameter of the droplet 13 that has landed on the surface of the substrate 4 greatly depends on the wettability between the surface of the substrate 4 and the droplet 12. Here, wetting refers to a phenomenon in which the surface of the substrate 4 disappears due to the landing of the droplet 12 on the surface of the substrate 4 and a new interface of the droplet 13 that has landed with the substrate 4 is generated. As shown in FIG. At the contact point of the droplet 13 that has landed on the surface of the substrate 4, the smaller the contact angle θ formed by the tangent drawn to the droplet 13 and the substrate 4, the higher the wettability, and vice versa. The nature is low. In the case of the droplets 12 having the same capacity, if the contact angle θ is small, the landed droplet 13 spreads greatly, and conversely, if the contact angle θ is large, it does not spread much.

  The wettability between the surface of the substrate 4 and the droplet 12 is determined by the difference obtained by subtracting the surface tension of the droplet 12 from the solid surface tension of the substrate 4. If this difference is positive, the droplet 12 completely wets and spreads to reduce the surface energy, and if it is negative, the landed droplet 13 has a specific contact angle θ. If the solid surface tension of the substrate 4 is not constant even if the surface tension of the droplet 12 is constant, the contact angle θ is not constant. Even if the individual diameters of the droplets 12 at the time of jetting are constant, if the wettability between the substrate 4 and the droplets 12 changes, the way in which each of the landed droplets 13 spread out will change. The diameter of the droplet 13 at the time of landing is not constant. Since a certain amount of work time is required to arrange the droplets 12 on the surface of the substrate 4, the change in the wettability between the surface of the substrate 4 and the droplets 12 with time is prevented in order to make the diameter of the landed droplets 13 constant. It is necessary to. If the diameter of the droplet 12 at the time of ejection is kept constant and the wetting and spreading of the landed droplet 13 is kept constant, a desired arrangement in which the diameter of the landed droplet 13 does not change can be obtained as shown in FIG.

  The solid surface tension on the surface of the substrate 4 depends on the characteristics of the substrate 4 itself, but it is the adhesion of the adsorbing substance to the surface of the substrate 4 that has a great influence on the temporal change of the solid surface tension. There are various adsorbing substances such as organic substances, moisture, and fine particles in the atmosphere. When the substrate 4 is left in the atmosphere, these adsorbed substances adhere to the surface of the substrate 4 and the surface state of the substrate 4 changes with time. Along with this, the solid surface tension of the substrate 4 changes with time, and the wettability between the surface of the substrate 4 and the droplets 12 changes with time.

  When arranging the droplets 12, such a problem can be avoided by controlling the atmosphere around the substrate 4. For example, the concentration of the organic substance that is one of the adsorbing substances is preferably controlled to 1% or less in the atmosphere around the substrate 4. By doing so, it is possible to prevent the organic substance, which is one of the adsorbing substances having a great influence on the wettability between the surface of the substrate 4 and the droplets 12, from adhering to the surface of the substrate 4 over time. A desired arrangement in which the diameter of the droplets 13 landed on the surface does not change is obtained.

  The control method is not particularly limited as long as the atmosphere around the substrate 4 can be controlled. However, the atmosphere around the substrate 4 is replaced from the atmosphere by an inert gas such as nitrogen gas or argon gas having a low adsorbed substance concentration. It is preferable. The atmosphere can be replaced by a method in which the gas is continuously supplied from the gas supply device 14 to the case 6 or the case 6 is sealed when the replacement between the atmosphere and the inert gas is completed. Further, a surface treatment means for the substrate 4 described later, for example, a method of irradiating ultraviolet rays when arranging the droplets 12 may be used. In order to perform the atmosphere replacement in the case 6 more completely, it is preferable to perform preliminary replacement with an inert gas at atmospheric pressure in advance and then perform degassing replacement using the pressure maintaining mechanism 15. Note that if deaeration is performed without pre-substitution with an inert gas at atmospheric pressure, moisture in the atmosphere is condensed due to adiabatic expansion, and on the contrary, the concentration of the adsorbed substance in the atmosphere is increased.

Further, when the substrate 4 is installed in this apparatus, it is preferable to perform surface treatment of the substrate 4 in advance to control the wettability between the surface of the substrate 4 and the droplets 12. In this way, the spread due to the wettability of the droplet diameter that has landed can be controlled in advance, so that by accurately controlling the droplet diameter at the time of ejection, a desired arrangement in which the droplet diameter that has landed on the substrate surface is accurate can be obtained. can get. If the wettability is controlled for each landing position in advance, even when the droplets 12 having the same diameter at the time of ejection are ejected, an array in which the diameters of the landed droplets 13 are different as shown in FIG. 4 can be obtained. Further, an array in which the diameters of the landed droplets 13 are different can be obtained even if the wettability of each part on the surface of the substrate is constant and the diameter of the droplets 12 at the time of ejection is changed.
As a surface treatment method of the substrate 4, a method of irradiating the substrate 4 with ultraviolet rays, ozone gas, or plasma gas, cleaning the substrate 4 with hydrogen peroxide, or treating the surface of the substrate 4 with a silane coupling agent can be used. . The contact angle between the substrate 4 and the droplet 13 is not necessarily better as it is larger or smaller, and may be arbitrarily selected according to the purpose of arranging the droplets.

The inside of the case 6 can be maintained at a reduced pressure or a pressurized state by using the pressure maintaining mechanism 15. The pressure maintaining mechanism 15 is usually configured by a pump, a pressure valve, or the like, but there is no particular limitation on the configuration as long as the inside of the case 6 can be maintained in a reduced pressure or pressurized state. Moreover, although the pressure maintenance mechanism 15 is installed in the gas outlet 6b side in FIG. 1, there is no special restriction | limiting in an installation site | part, and it is not necessary to install collectively in one location.
When the inside of the case 6 is maintained in a reduced pressure or pressurized state, the case of the inside of the case 6 under normal pressure in terms of the properties of the liquid 11 and the drying speed of the landed droplet 13 or the wettability between the surface of the substrate 4 and the droplet 12. Can be controlled in different states, the pressure in the case 6 may be arbitrarily set according to the desired droplet arrangement.

  According to the present invention, not only the arrangement of the droplets 13 but also the fine particles can be arranged on the surface of the substrate 4. If a dispersion liquid in which fine particles are dispersed is used as the liquid 11, droplets 12 containing fine particles are generated. The inclusion of fine particles means a state in which one or a plurality of fine particles are present on the surface or inside of the droplet 12. The droplets 12 enclosing the fine particles are jetted onto the surface of the substrate 4, the respective droplets 12 are arranged, and the liquid component of the droplets 13 is removed, whereby the fine particles can be arranged on the surface of the substrate 4. Removal of the liquid component of the droplet 13 can be performed, for example, by drying.

  When a plurality of fine particles are encapsulated in the liquid droplet 12, the drying speed of the liquid component of the liquid droplet 13 and the internal flow velocity of the liquid component movement associated therewith are determined by the contact angle θ between the substrate 4 and the liquid droplet 13. Since the diameter of the landed droplet 13 hardly changes during the drying process, by changing the contact angle θ, the characteristics of the liquid 11 and the shape of the solid fine particles, various structures within the diameter range of the droplet 13 can be obtained. The fine particle aggregate can be left on the surface of the substrate 4.

Fine particles are more difficult to disperse in air than in liquid. For this reason, it is very difficult to make an aggregate in which the fine particles are arbitrarily arranged in the air. However, if the method according to the present invention is used, the fine particles dispersed in the liquid 11 are dense and orderly aggregates. Or sparse and random aggregates can be easily created. The structure control of the aggregate can be performed by controlling the internal flow generated by drying the liquid component of the landed droplet 13 in addition to the properties of the dispersion. Since the drying speed of the liquid component greatly depends on the contact angle θ of the landed droplet 13, it is important to control the wettability between the surface of the substrate 4 and the droplet 12.
Since the diameter of the landed droplet 13 hardly changes during the drying process, the size of the fine particle aggregate is substantially equal to the diameter of the landed droplet 13. By arranging the liquid droplets 13 and removing the liquid components, fine particle aggregates having various aggregate structures can be arranged on the surface of the substrate 4 in any size.

Using the apparatus shown in FIG. 1, an experiment was conducted on how the presence or absence of surface treatment on the substrate affects the wettability between the substrate surface and the droplets. Corning 1737 glass (manufactured by Corning) was used for the substrate, and pure water was used for the liquid. An array of droplets having a diameter of about 100 μm at the time of ejection was obtained by ejecting 1.1 picoliter droplets. The contact angle was measured by photographing a droplet landed on the substrate with a CCD camera and analyzing the image.
When the purchased substrate was used as it was, the contact angle of the landed droplet was about 40 ° (see FIG. 5). On the other hand, after the purchased substrate was immersed in hydrogen peroxide water and subjected to ultrasonic cleaning at 50 Hz for 10 minutes, a substrate irradiated with 20 mW / cm ² ultraviolet rays from a low-pressure mercury lamp at a distance of 1 cm for 30 seconds was used. However, the contact angle of the landed droplets was less than 5 ° and almost completely spread out, and the shape of the droplets could not be visually recognized (see FIG. 6).

Using the apparatus shown in FIG. 1, an experiment was conducted to determine how the presence or absence of atmosphere control when arranging droplets on the substrate surface affects the contact angle. After subjecting the substrate to surface treatment by the same method as in Example 1, pure water droplets were jetted onto the substrate to obtain a droplet array.
Contact angle of the landed droplet when the atmosphere in the case is left as it is and when the case is sealed after high purity argon gas is blown into the case at a rate of 1 liter per minute for 30 minutes The measurement results are shown in FIG. The former is indicated by a solid line, and the latter is indicated by a broken line. It can be seen that the former contact angle increases with time, while the latter contact angle hardly changes.

  Using the apparatus shown in FIG. 1, an array of fine particle aggregates was produced on a substrate. A dispersion obtained by adding polystyrene fine particles (manufactured by Interfacial Dynamics) having a particle diameter of 1 μm to a 0.05 wt% solution of hexametaphosphoric acid so as to be 5 vol% and treating with a ultrasonic homogenizer for 3 minutes was used as a liquid. After droplets of 2.5 microliters were jetted onto a glass substrate to obtain a droplet array, drying was performed at 25 ° C. to obtain an array of fine particle aggregates. The obtained fine particle aggregate is shown in FIG.

  The present invention provides a method and apparatus for arranging desired droplets on the surface of a substrate by controlling the diameter of the droplets that are landed by ejecting the droplets onto a desired portion of the substrate, and a fine particle array having an arbitrary aggregate structure. Therefore, it contributes to various industries such as the manufacture of circuit boards.

Schematic configuration diagram of a droplet arrangement device according to the present invention Diagram showing contact angle between droplet and substrate Diagram showing one example of droplet arrangement state Diagram showing one example of droplet arrangement state A photograph showing a contact angle between a substrate and a droplet not subjected to surface treatment (Example 1) A photograph showing the contact angle between a surface-treated substrate and a droplet (Example 1) Graph showing difference in contact angle by atmosphere control (Example 2) Photograph of fine particle aggregate (Example 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 2 Ejector 3 Ejector support mechanism 4 Base | substrate 5 Base | substrate support mechanism 6 Case 6a Gas inlet 6b Gas outlet 7 Cap 8 Lens body 9 Piezoelectric element 10 Acoustic transmission medium 11 Liquid 12 Droplet 13 Landing droplet 14 Gas supply 15 Pressure Maintenance mechanism θ Contact angle

Claims (8)

  A droplet arranging method for arranging droplets on a substrate surface by ejecting the droplets onto a desired portion of the substrate, wherein the droplets prevent change in wettability between the substrate surface and the droplets over time Array method.   The droplet arranging method according to claim 1, wherein the atmosphere around the substrate is replaced with an inert gas from the atmosphere in order to prevent the wettability from changing with time.   3. The droplet arranging method according to claim 1, wherein the substrate surface is treated so as to have a predetermined wettability, and then the droplets are ejected onto the substrate surface.   The droplet arranging method according to claim 1, wherein the droplet is made of a dispersion liquid in which fine particles are dispersed.   A fine particle array obtained by removing liquid components from droplets on a substrate surface arranged by the droplet arranging method according to claim 4.   A container that holds a liquid, an acoustic generator that generates acoustic energy, a lens that focuses the acoustic energy generated by the acoustic generator onto the liquid in the container, and droplets ejected from the liquid surface adhere to the container. A droplet arranging apparatus comprising a holding means for holding a base and a means for controlling an atmosphere around the base.   7. The droplet arrangement device according to claim 6, wherein the means for controlling the atmosphere around the substrate includes at least a case in which the substrate can be accommodated, and a gas supplier for supplying an inert gas into the case. .   7. The droplet arrangement device according to claim 6, wherein the means for controlling the atmosphere around the substrate includes at least a case capable of accommodating the substrate therein and a means for maintaining the inside of the case in a reduced pressure or pressurized state.