JP2012135744A - Droplet ejection method and droplet ejection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet ejection method and a droplet ejection apparatus by means of which a state of a droplet ejected from a nozzle can be changed and a film formed of a liquid material can be formed on a receipt thing with high precision.SOLUTION: A first ejection method or a second ejection method is chosen. In the first ejection method, a base material S is arranged between a droplet ejection head 2 which ejects a liquid material 10 having electrostatic chargeability as a droplet D from a nozzle 261 formed at a nozzle plate 26 having electrical conductivity and an electrode 31 which is arranged facing the droplet ejection head 2 in an ejection direction of the liquid material 10 and then the liquid material 10 is ejected as the droplet from the nozzle 261 in a state where potential difference is produced between the nozzle plate 26 and the electrode 31 and thereby the droplet D is supplied to the base material S in a mist state where the droplet is divided to two or more minute droplets smaller than the original droplet. In the second ejection method, the droplet of the liquid material 10 ejected from the nozzle 261 is supplied to the base material S in a state where potential difference between the nozzle plate 26 and the electrode 31 is smaller than that in the first ejection method.

Description

  The present invention relates to a droplet discharge method and a droplet discharge device.

For example, as a method of applying a liquid material for a conductor pattern (wiring), a liquid material for a color filter, or a liquid material for printing on a substrate, an inkjet method in which the liquid material is discharged in the form of droplets from a liquid discharge head Is widely known (see, for example, Patent Document 1).
A liquid discharge head used in the ink jet method includes a nozzle plate in which nozzles are formed, a cavity that communicates with the nozzles and that is filled with a liquid material, and a piezoelectric element that changes the pressure in the cavity. Then, the liquid material is ejected as droplets from the nozzle by increasing the pressure in the cavity by the piezoelectric element.

  However, such an ejection head can only supply the droplets ejected from the nozzles as they are, that is, as a single droplet onto the substrate. In other words, since the state of the liquid droplets ejected from the nozzle cannot be changed as necessary, a film (conductor pattern, color filter, image, etc.) formed on the substrate with a liquid material is formed with high accuracy. There is a problem that can not be.

  More specifically, taking the case of a conductor pattern as an example, the conductor pattern includes a linear portion such as a wiring and a planar portion such as a terminal (connection pad). In the conventional method, the droplets ejected from the nozzle can be made relatively small, so that a thin wiring can be formed. However, for the terminals, the droplets must be supplied to the surface multiple times while shifting the discharge position, the thickness of the formed terminals becomes uneven, and problems with connection to other members may occur. The electrical resistance of the terminals may become uneven.

JP 2007-84387 A

  An object of the present invention is to provide a droplet discharge method and a droplet discharge device capable of changing the state of a droplet discharged from a nozzle and forming a film made of a liquid material on a receptor with high accuracy. Is to provide.

Such an object is achieved by the present invention described below.
The droplet ejection method of the present invention includes a droplet ejection head that ejects a liquid material having charging properties as droplets from a nozzle formed on a conductive nozzle plate, and the droplet ejection head and ejection of the liquid material. A receptor for supplying the liquid material discharged from the droplet discharge head is disposed between electrodes opposed to each other in a direction, and a potential difference is generated between the nozzle plate and the electrode. A first discharge method for discharging the liquid material as droplets from a nozzle and supplying the droplets to the receiver in the form of a mist divided into a plurality of micro droplets smaller than the droplets; and the nozzle Selecting a second discharge method in which a potential difference between the plate and the electrode is made smaller than that in the first discharge method and droplets of the liquid material discharged from the nozzle are supplied to the receptor. To.
Accordingly, it is possible to provide a droplet discharge method that can change the state of the droplet discharged from the nozzle and can form a film made of a liquid material on the receptor with high accuracy.

In the droplet discharge method of the present invention, in the first discharge method, the droplet of the liquid material discharged from the nozzle is charged in a potential space generated between the nozzle plate and the electrode, and the charging is performed. It is preferable that the plurality of fine droplets are split by the electrostatic repulsive force generated by.
Thereby, in the first ejection method, it is possible to more reliably divide the droplet into a plurality of micro droplets.

In the droplet discharge method of the present invention, in the first discharge method, the liquid material droplet discharged from the nozzle preferably has a charge repulsive force acting on the droplet larger than the surface tension.
Thereby, in the first ejection method, it is possible to more reliably divide the droplet into a plurality of micro droplets.
In the droplet discharge method of the present invention, in the first discharge method, the surface tension acting on the droplet of the liquid material discharged from the nozzle is T, the charge amount of the droplet is Q, It is preferable that the relationship T ≦ Q ² / 64π ² ε ₀ R ³ is satisfied, where R is the radius, ε ₀ is the dielectric constant of the vacuum, and π is the circumference.
Thereby, in the first ejection method, it is possible to more reliably divide the droplet into a plurality of micro droplets.

In the droplet discharge method of the present invention, the electrical conductivity of the liquid material is preferably 1 × 10 ⁻¹² S / m or more and 1 × 10 ⁻² S / m or less.
Thereby, it is possible to more reliably divide the droplet into a plurality of minute droplets.
In the droplet discharge method of the present invention, in the second discharge method, the liquid material droplet discharged from the nozzle preferably has a charge repulsive force acting on the droplet smaller than the surface tension.
Thereby, in the second ejection method, it is possible to prevent the droplets from being split as in the first ejection method.

In the droplet discharge method of the present invention, the droplet discharge head includes a cavity that is filled with the liquid material and communicates with the nozzle, and a pressure generation unit that changes the pressure in the cavity, and the piezoelectric element It is preferable that the liquid material is discharged from the nozzle by driving.
Thereby, since the discharge of the droplet can be performed by driving the piezoelectric generator, the atomization of the droplet can be realized with power saving.

In the droplet discharge method of the present invention, in the first discharge method, the average droplet diameter of the micro droplets is preferably 1 nm or more and 10 μm or less.
Thereby, the film made of the liquid material formed on the receptor can be made sufficiently thin and the thickness of the film can be made uniform.
In the droplet discharge method of the present invention, the landing area of the droplet discharged by the first discharge method on the receptor is larger than the landing area of the droplet discharged by the second discharge method on the receptor. It is preferable.
Thereby, the film thickness of the terminal formed on the receptor by the first discharge method can be made sufficiently thin, and the film thickness can be made uniform.

In the droplet discharge method of the present invention, it is preferable that the liquid material is a liquid material for wiring formation for forming a conductor pattern on the receptor.
This simplifies the manufacture of a circuit board with a circuit formed on the receptacle and improves the electrical characteristics of the circuit board.
In the droplet discharge method of the present invention, the wiring material forming the conductor pattern formed on the receptor is supplied with the liquid material by the second supply method, and the terminal having a surface shape is the first wiring. It is preferable to supply the liquid material by one supply method.
Thereby, the conductor pattern which is excellent in an electrical property can be formed.

In the droplet discharge method of the present invention, it is preferable that the liquid material is obtained by dispersing metal particles in a dispersion medium.
Thereby, it becomes a liquid material suitable for forming a conductor pattern.
A droplet discharge device of the present invention includes a droplet discharge head that discharges a liquid material having charging properties as droplets from a nozzle formed on a nozzle plate having conductivity,
An electrode disposed opposite to the liquid droplet ejection head in the liquid material ejection direction;
A potential difference generating means for generating a potential difference between the nozzle plate and the electrode;
By discharging the liquid material as droplets from the nozzle in a state in which a potential difference is generated between the nozzle plate and the electrode by the potential difference generating means, the droplet is made into a plurality of microscopic droplets smaller than the droplet. A first discharge method for supplying a receiver disposed between the droplet discharge head and the electrode in the form of a mist divided into droplets; and a potential difference between the nozzle plate and the electrode. It is possible to select a second ejection method in which the liquid material droplets ejected from the nozzle are supplied to the receiver without being divided into mists in a state smaller than the one ejection method.
Accordingly, it is possible to provide a droplet discharge device that can change the state of the droplet discharged from the nozzle and can form a film made of a liquid material on the receptor with high accuracy.

It is a perspective view which shows schematic structure of the droplet discharge apparatus of this invention. It is a schematic diagram for demonstrating schematic structure of the inkjet head and table with which the droplet discharge apparatus shown in FIG. 1 is provided. It is a schematic diagram for demonstrating the action | operation of the droplet discharge apparatus shown in FIG. It is a schematic diagram for demonstrating the action | operation of the droplet discharge apparatus shown in FIG. It is a schematic diagram for demonstrating the manufacturing method of a circuit board.

Hereinafter, preferred embodiments of the present invention will be described in detail.
<Droplet ejection device>
First, an example of the droplet discharge device of the present invention will be described.
1 is a perspective view showing a schematic configuration of a droplet discharge device of the present invention, FIG. 2 is a schematic diagram for explaining a schematic configuration of an inkjet head and a table provided in the droplet discharge device shown in FIG. 4 is a schematic diagram for explaining the operation of the droplet discharge device shown in FIG. 1, and FIG. 5 is a schematic diagram for explaining a circuit board manufacturing method. In FIG. 1, the X direction, the Y direction, and the Z direction are directions orthogonal to each other.
As shown in FIGS. 1 and 2, the droplet discharge device 1 includes an inkjet head (droplet discharge head) 2, a table 3 on which a substrate (acceptor) S is placed, and voltage application means (potential difference generation means). ) 4 and a control device 100 for controlling these drives. Hereinafter, each of these components will be described in detail.

(Inkjet head)
The inkjet head 2 can be moved and positioned in the X direction by the first moving means 61. The inkjet head 2 can be moved and positioned in the Z direction by a linear motor 51. The inkjet head 2 can be swung (rotated) and positioned in the α, β, and γ directions by motors 52, 53, and 54, respectively.

As shown in FIG. 2, the inkjet head 2 has a head body 21. The head body 21 includes a reservoir 211 and a plurality of ink chambers 212 branched from the reservoir 211. The reservoir 211 is a flow path for supplying the liquid material 10 to each ink chamber 212.
An ink storage tank (not shown) is connected to the reservoir 211 via a transport path. The liquid material 10 is stored in the ink storage tank, and the liquid material 10 stored in the ink storage tank is transported to the reservoir 211 via the transport path.

A nozzle plate 26 that constitutes an ink ejection surface is attached to the lower end surface (the surface on the table 3 side) of the head body 21. In the nozzle plate 26, a plurality of nozzles 261 that discharge the liquid material 10 are formed corresponding to the ink chambers 212. A flow path of the liquid material 10 is formed from each ink chamber 212 toward the corresponding nozzle 261.
The nozzle plate 26 is made of, for example, a metal material such as gold, silver, copper, aluminum, or an alloy containing these, and has conductivity. The nozzle plate 26 is electrically connected to the voltage application unit 4.

As long as the nozzle plate 26 has conductivity, the constituent material thereof is not particularly limited. For example, in addition to the above-described metal materials, carbon-based materials such as carbon nanotubes, graphene, and fullerene, polythiophene, polyacetylene, An ion conductive polymer in which an ionic substance such as NaCl, Cu (CF ₃ SO ₃ ) ₂ is dispersed in a matrix resin such as polyfluorene or a derivative thereof, or a matrix resin such as polyvinyl alcohol or polycarbonate. Examples include various conductive materials such as conductive oxide materials such as materials, indium oxide (IO), indium tin oxide (ITO), and fluorine-doped tin oxide (FTO).

In addition, the nozzle plate 26 may be subjected to a process of electrically insulating other than the surface facing the sheet-like electrode 31 described later, for example. Thereby, unintentional electric leakage etc. to the inside of the inkjet head 2 can be prevented.
Further, the nozzle plate 26 may be formed, for example, by forming a conductive layer made of a conductive material as described above on the surface of a base made of an insulating resin material.

  A diaphragm 22 is attached to the upper end surface of the head body 21. The diaphragm 22 constitutes a part of the wall surface of each ink chamber 212. Piezo elements (piezoelectric elements: pressure generating portions) 23 are provided outside the diaphragm 22 corresponding to the ink chambers 212. The piezo element 23 is obtained by sandwiching a piezoelectric material such as quartz with a pair of electrodes. The piezo element 23 (a pair of electrodes) is electrically connected to the drive circuit 24.

When an electric signal is input from the drive circuit 24 to the piezo element 23, the piezo element 23 is expanded or contracted. When the piezo element 23 contracts and deforms, the pressure in the ink chamber 212 decreases, and the liquid material 10 flows from the reservoir 211 into the ink chamber 212. Further, when the piezo element 23 expands and deforms, the pressure in the ink chamber 212 increases and the liquid material 10 is ejected from the nozzle 261.
Note that the amount of deformation of the piezo element 23 can be controlled by changing the applied voltage. Further, the deformation speed of the piezo element 23 can be controlled by changing the frequency of the applied voltage. That is, the discharge condition of the liquid material 10 can be controlled by controlling the voltage applied to the piezo element 23.

By using such a piezo method as the inkjet head 2, it is possible to achieve power saving driving. That is, according to the piezo method, since the liquid material 10 can be discharged by driving the piezo element 23, the electrostatic force generated when a voltage is applied between the nozzle plate 26 and the electrode 31 is generated by the liquid material 10. Acts only on the splitting (atomization). Thereby, since the voltage applied between the nozzle plate 26 and the electrode 31 can be made smaller, power saving of the apparatus can be achieved.
Further, in the piezo method, almost no heat is generated, so that no heat is applied to the liquid material 10, and alteration or the like of the liquid material 10 can be prevented. The method for ejecting the liquid material 10 is not limited to the piezo method described above, and for example, a bubble jet (registered trademark) method in which ink is ejected by bubbles generated by heating the liquid material 10 may be applied. it can.

(Table 3)
As shown in FIG. 1, the table 3 can be moved and positioned in the Y direction by the second moving means 62, and can be swung (rotated) and positioned in the θz direction by the motor 55.
A film-like (plate-like) electrode 31 is formed on the upper surface of the table 3. This electrode 31 is electrically connected to the voltage applying means 4.

The constituent material of the electrode 31 is not particularly limited as long as it has conductivity. For example, a metal material such as gold, silver, copper, aluminum or an alloy containing these, or a carbon-based material such as carbon nanotube, graphene, or fullerene. An ionic substance such as NaCl, Cu (CF ₃ SO ₃ ) ₂ is dispersed in a material, an electroconductive polymer material such as polythiophene, polyacetylene, polyfluorene or a derivative thereof, or a matrix resin such as polyvinyl alcohol or polycarbonate. In addition, various conductive materials such as conductive oxide materials such as ion conductive polymer materials, indium oxide (IO), indium tin oxide (ITO), and fluorine-doped tin oxide (FTO) can be used.
In addition, by configuring the table 3 with, for example, a metal material, the table 3 can exhibit an electrode function, and the electrode 31 can be omitted. In other words, the table 3 can also serve as the electrode 31.

(Voltage application means)
As shown in FIG. 2, a nozzle plate 26 included in the inkjet head 2 and an electrode 31 included in the table 3 are electrically connected to the voltage applying unit 4. The voltage application unit 4 has a function of applying a voltage between the nozzle plate 26 and the electrode 31, that is, a function of generating a potential difference between the nozzle plate 26 and the electrode 31.
By providing such a voltage application unit 4, the first ejection method and the second ejection method in which the states of droplets ejected from the inkjet head 2 are different from each other can be changed as described below.

-First discharge method-
The first discharge method is a discharge method for supplying droplets discharged from the inkjet head 2 to the substrate S in the form of mist.
For example, as shown in FIG. 3, when a voltage is applied between the nozzle plate 26 and the electrode 31 by the voltage applying unit 4 so that the nozzle plate 26 has a negative potential and the electrode 31 has a positive potential, the nozzle plate 26 An electric field E is generated between the electrode 31 and the electrode 31. When the droplet D of the liquid material 10 is discharged from the inkjet head 2 in a state where the electric field E is generated, the droplet D is dispersed in a mist form. That is, the droplet D ejected from the inkjet head 2 is split into a plurality of minute droplets D1 having a smaller volume.

  This phenomenon will be described in detail. When the liquid material 10 is ejected as a droplet D from the inkjet head 2 in a state where the electric field E is generated, the droplet D is negatively charged by the action of the electric field E. As described above, the negatively charged droplets D are mainly subjected to the charge repulsive force in the outward direction shown in FIG. 4A and the surface tension in the inward direction shown in FIG. 4B. If the charge repulsive force is larger than the surface tension, the droplet D cannot maintain a stable spherical shape and is divided (dispersed) into a plurality of minute droplets D1.

Even when the voltage application unit 4 applies a voltage between the nozzle plate 26 and the electrode 31 such that the nozzle plate 26 has a positive potential and the electrode 31 has a negative potential, the droplet D is positively charged. Except for the above, the liquid droplets are divided into a plurality of microdroplets D1 as described above.
As described above, as a method for splitting the droplet D into the plurality of micro droplets D1, for example, a method of making the charge repulsive force acting on the droplet D larger than the surface tension can be cited. That is, there is a method in which the droplet D is overcharged. In order to satisfy this condition, the surface tension acting on the droplet D is T, the charge amount of the droplet D is Q, the radius of the droplet D is R, the dielectric constant of the vacuum is ε ₀ , and the circumference ratio If π is π, the following formula (1) may be satisfied.
T ≦ Q ² / 64π ² ε ₀ R ³ (1)

Here, in order to satisfy the above formula (1), the radius R of the droplet D can be reduced by controlling the deformation amount of the piezo element 23 or between the nozzle plate 26 and the electrode 31 as necessary. The amount of charge Q may be increased by controlling the magnitude of the voltage applied to. Further, both the radius R and the charge amount Q may be controlled.
Both of these two methods are preferable because they are relatively easy to control, but a method of controlling the charge amount Q is more preferable. Thereby, the droplet D can be divided into the minute droplets D1 while keeping the radius R of the droplet D constant, so that a more uniform film can be formed on the substrate S. Also, controlling the magnitude of the voltage applied between the nozzle plate 26 and the electrode 31 is simpler than controlling the amount of deformation of the piezo element 23, and the control is not required to be accurate.

It should be noted that the equation (1) indicates that even if the droplet D at the moment of being ejected from the inkjet head 2 is not satisfied, liquid such as a solvent evaporates during the flight of the droplet D, resulting in overcharging. You may be more satisfied.
The average droplet diameter of the fine droplets D1 is not particularly limited, but is preferably about 1 nm to 10 μm. Thereby, the thickness of the film formed by drying the coating film made of the liquid material 10 supplied onto the substrate S can be further reduced, and the drying time of the coating film can be further shortened. Can do.

  The landing area of the droplets D (aggregates of minute droplets D1) supplied onto the substrate S by such a first discharge method is the droplets D supplied onto the substrate S by the second discharge method described later. Is larger than the landing area. In other words, according to the first ejection method, the liquid material 10 can be supplied in a wider range than the second ejection method when compared with the droplets D and 1 droplet. A planar portion can be formed.

-Second discharge method-
The second discharge method is a discharge method in which the droplets discharged from the inkjet head 2 are supplied to the substrate S as they are, that is, as one droplet.
In such a second ejection method, the voltage application means 4 does not apply a voltage between the nozzle plate 26 and the electrode 31, that is, no electric field is generated between the nozzle plate 26 and the electrode 31. Then, the liquid material 10 is discharged as droplets D from the inkjet head 2. Thereby, since the charge repulsive force does not substantially act on the droplet D ejected from the ink jet head 2, the droplet D ejected from the ink jet head 2 is split into micro droplets D1 as in the first ejection method. It flies without being supplied and is supplied to the substrate S as it is (as one droplet).

In the second ejection method, a charge repulsive force may act on the droplet D, but the acting charge repulsive force must be smaller than the surface tension acting on the droplet D. In other words, as long as the following formula (2) is satisfied, voltage application between the nozzle plate 26 and the electrode 31 by the voltage application unit 4 may be performed. In this way, by making the charge repulsive force acting on the droplet D smaller than the surface tension, it is possible to reliably prevent the droplet D from being split as in the first ejection method.
T> Q ² / 64π ² ε ₀ R ³ (2)

  The first discharge method and the second discharge method have been described above. Switching between the first discharge method and the second discharge method can be easily and reliably performed by whether or not a voltage is applied between the nozzle plate 26 and the electrode 31, that is, by controlling the voltage application unit 4. Moreover, since the switching between the first discharge method and the second discharge method can be performed instantaneously, the liquid material 10 can be smoothly supplied to the substrate S.

  According to the first discharge method, since the droplets D are supplied in the form of a mist to the substrate S, for example, compared with the second discharge method, the thickness of the film formed on the substrate S is reduced and It can be made uniform. On the other hand, according to the second ejection method, since the droplets D are not atomized unlike the first ejection method, for example, the liquid material 10 is supplied in a narrower range compared to the first ejection method. (That is, the landing area of the droplet D can be reduced as compared with the first ejection method). Thus, the first discharge method and the second discharge method have different characteristics, respectively, and a film with higher accuracy can be formed on the substrate S by properly using these two discharge methods. .

The droplet discharge device 1 is a device that is particularly effective for forming a conductor pattern on the substrate S with the liquid material 10. Specifically, the conductor pattern includes linear wiring and planar terminals (connection pads), and the wiring has a narrow width for the purpose of improving the functionality of the conductor pattern (circuit). The terminals are required to have a uniform film thickness. Therefore, when the droplet discharge device 1 is used, the liquid material 10 is supplied by the second discharge method to the portion corresponding to the wiring of the conductor pattern, and the liquid material 10 is supplied to the portion corresponding to the terminal by the first discharge method. By doing so, it is possible to easily and accurately form a conductor pattern having a wiring with a narrowed width and a terminal with a uniform thickness.
The droplet discharge device 1 has been described above.

<Liquid material>
Next, the liquid material 10 supplied by the droplet discharge device 1 will be described.
The liquid material 10 is not particularly limited as long as the droplet D can be charged when the electric field E is applied, and may be a material for forming a conductor pattern, for example, a color filter provided in a liquid crystal display or the like It may be a material for forming an image or a printing material for printing an image.

When the liquid material 10 is a material for forming a conductor pattern, a circuit board having excellent electrical characteristics can be formed as will be described later. When the liquid material 10 is a material for forming a color filter, A thin color filter having a uniform film thickness can be easily formed, and when it is a printing material, an image excellent in gradation expression can be printed.
Below, the material for forming wiring is demonstrated typically.
As the liquid material 10 for forming the conductor pattern, for example, a dispersion liquid in which silver particles (metal particles) are dispersed in an aqueous dispersion medium (dispersion medium) can be suitably used. By setting it as such a structure, it becomes a liquid material suitable for forming a conductor pattern.

[Aqueous dispersion medium]
In the present specification, the “aqueous dispersion medium” refers to one composed of water and / or a liquid excellent in compatibility with water (for example, a liquid having a solubility in 100 g of water at 25 ° C. of 30 g or more). As described above, the aqueous dispersion medium is composed of water and / or a liquid having excellent compatibility with water, but is preferably composed mainly of water. It is preferably 70 wt% or more, more preferably 90 wt% or more. Thereby, the effect mentioned above is exhibited more notably.

Specific examples of the aqueous dispersion medium include, for example, water, methanol, ethanol, butanol, propanol, isopropanol and other alcohol solvents, 1,4-dioxane, tetrahydrofuran (THF) and other ether solvents, pyridine, pyrazine, pyrrole and the like. Aromatic heterocyclic compound solvents, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, and aldehyde solvents such as acetaldehyde. Of these, one or a combination of two or more can be used.
In addition, the content of the aqueous dispersion medium in the liquid material 10 is preferably 20 wt% or more and 80 wt% or less, and more preferably 25 wt% or more and 70 wt% or less. Thereby, while making the viscosity of the liquid material 10 suitable, the change of the viscosity by volatilization of a dispersion medium can be made small.

[Silver particles]
Next, silver particles (metal particles) will be described.
Silver particles are the main component of the conductor pattern to be formed, and are components that impart conductivity to the conductor pattern. Such silver particles are dispersed in the liquid material 10.
The average particle size of the silver particles is preferably 1 nm or more and 100 nm or less, and more preferably 10 nm or more and 40 nm or less. Thereby, the discharge stability of the liquid material 10 can be further increased, and a fine conductor pattern can be easily formed. In the present specification, the “average particle size” means a volume-based average particle size unless otherwise specified.

Further, the silver particles contained in the liquid material 10 (the content of silver particles on which the dispersant is not adsorbed on the surface is preferably 0.5 wt% or more and 60 wt% or less, and is 10 wt% or more and 45 wt% or less. As a result, disconnection of the conductor pattern can be more effectively prevented, and a more reliable conductor pattern can be formed.
Further, the silver particles are preferably dispersed in an aqueous dispersion medium as silver colloid particles having a dispersant attached to the surface thereof. Thereby, the dispersibility of the silver particles in the aqueous dispersion medium is particularly excellent, and the discharge stability of the liquid material 10 is particularly improved.

  Although it does not specifically limit as a dispersing agent, it has 3 or more of COOH groups and OH groups, and the number of COOH groups is the same as that of OH groups, or contains hydroxy acid or its salt more than it. Is preferred. These dispersants adsorb on the surface of silver particles to form colloidal particles, and the colloidal liquid is stabilized by uniformly dispersing silver colloidal particles in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Has the function of

As described above, since the silver colloidal particles are stably present in the liquid material 10, a fine conductor pattern can be more easily formed. Further, silver particles are uniformly distributed in the pattern formed by the liquid material 10, and cracks, disconnections, and the like are less likely to occur. Examples of such a dispersing agent include citric acid, malic acid, trisodium citrate, tripotassium citrate, trilithium citrate, triammonium citrate, disodium malate, tannic acid, gallotannic acid, and pentaploid tannin. Of these, one or a combination of two or more can be used.
The content of the silver colloid particles in the liquid material 10 is preferably 1 wt% or more and 60 wt% or less, more preferably 5 wt% or more and 50 wt% or less.
Further, the heat loss to 500 ° C. in the thermogravimetric analysis of the silver colloid particles is preferably 1 wt% or more and 25 wt% or less.

[Organic binder]
The liquid material 10 may contain an organic binder. The organic binder prevents aggregation of silver particles in the conductor pattern precursor formed using the liquid material 10. The organic binder has a function of improving the adhesion of the liquid material 10 to the substrate S.

  Although it does not specifically limit as an organic binder, For example, polyethyleneglycol # 200 (weight average molecular weight 200), polyethyleneglycol # 300 (weight average molecular weight 300), polyethyleneglycol # 400 (average molecular weight 400), polyethyleneglycol # 600 ( Weight average molecular weight 600), polyethylene glycol # 1000 (weight average molecular weight 1000), polyethylene glycol # 1500 (weight average molecular weight 1500), polyethylene glycol # 1540 (weight average molecular weight 1540), polyethylene glycol # 2000 (weight average molecular weight 2000), etc. Polyethylene glycol, polyvinyl alcohol # 200 (weight average molecular weight: 200), polyvinyl alcohol # 300 (weight average molecular weight: 300), polyvinyl alcohol # 400 (average molecular weight: 400), polyvinyl alcohol # 600 (weight average molecular weight: 600), polyvinyl alcohol # 1000 (weight average molecular weight: 1000), polyvinyl alcohol # 1500 (weight average molecular weight: 1500), polyvinyl alcohol # Polyglycerin compounds having a polyglycerin skeleton such as polyvinyl alcohol such as 1540 (weight average molecular weight: 1540), polyvinyl alcohol # 2000 (weight average molecular weight: 2000), polyglycerin, polyglycerin ester, etc. Alternatively, two or more kinds can be used in combination. Examples of polyglycerol esters include polyglycerol monostearate, tristearate, tetrastearate, monooleate, pentaoleate, monolaurate, monocaprylate, polycinnolate, sesquistearate, decaoleate, and sesquioleate. Etc.

(Drying inhibitor)
The liquid material 10 may contain a drying inhibitor. The drying inhibitor prevents unintended volatilization of the aqueous dispersion medium in the liquid material 10. As a result, it is possible to prevent the aqueous dispersion medium from volatilizing in the vicinity of the nozzle 261 of the droplet discharge device 1, and to suppress the increase in viscosity and drying of the liquid material 10. Examples of such a drying inhibitor include compounds represented by the following formula (I), alkanolamines, sugar alcohols, and the like, and one or more of them can be used in combination.

（ただし、Ｒ、Ｒ’は、それぞれ、Ｈまたはアルキル基である。）

(However, R and R ′ are each H or an alkyl group.)

[Surface tension modifier]
The liquid material 10 may contain a surface tension adjuster. The surface tension adjusting agent has a function of adjusting the contact angle between the liquid material 10 and the substrate S to a predetermined angle. Further, the surface tension adjusting agent may have a function of adjusting the liquid material 10 so as to satisfy the formula (1). As the surface tension adjusting agent, various surfactants can be used, and one or a combination of two or more types can be used. The contact angle between the liquid material 10 and the substrate S is predetermined with a small addition amount. It is preferable that an acetylene glycol type compound is included from a viewpoint which can be adjusted to this range.

  Examples of acetylene glycol compounds include Surfynol 104 series (104E, 104H, 104PG-50, 104PA, etc.), Surfynol 400 series (420, 465, 485, etc.), Olphine series (EXP4036, EXP4001, E1010, etc.). ("Surfinol" and "Orphine" are trade names of Nissin Chemical Industry Co., Ltd.) and the like, and one or more of these can be used in combination.

[Other ingredients]
In addition, the structural component of the liquid material 10 is not limited to the said component, You may contain components other than the above. Examples of such components include thiourea.
The viscosity of the liquid material 10 is not particularly limited, but is preferably 1.0 mPa · s or more and 15.0 mPa · s or less, and more preferably 4.0 mPa · s or more and 11.0 mPa · s or less. . Thereby, the discharge stability of the droplets can be improved, and the unintentional wetting and spreading of the liquid material 10 supplied to the substrate S can be more reliably prevented. Moreover, the droplet D can be easily divided into a plurality of minute droplets D1.
The example of the liquid material 10 has been described above.
The liquid material 10 preferably has a dielectric constant of about 1 × 10 ⁻¹² S / m or more and about 1 × 10 ⁻² S / m or less. Thereby, the droplet D can be more reliably divided into a plurality of minute droplets D1.

"Base material"
The substrate S to which the liquid material 10 is supplied is not particularly limited, and various materials can be used depending on the liquid material 10. Specifically, when the liquid material 10 is a material for forming a conductor pattern, a ceramic molded body (ceramic green sheet) can be used as the substrate S, and the liquid material 10 forms a color filter. When the liquid material 10 is a material for printing, various printing papers or the like can be used as the base material S.

<< How to use the droplet discharge device (droplet discharge method) >>
Next, a method of using the droplet discharge device 1 (droplet discharge method) will be described by taking as an example the case of forming a wiring substrate (laminated substrate). A wiring board is an electronic component used in various electronic devices. A circuit pattern consisting of various wirings, electrodes, etc., a multilayer ceramic capacitor, a multilayer inductor, an LC filter, a composite high-frequency component, etc. are formed on the substrate. It will be.

First, a ceramic green sheet as the substrate S is placed on the table 3. This ceramic green sheet can be manufactured, for example, as follows.
As shown in FIG. 5, first, as the raw material powder, ceramic powder made of alumina (Al ₂ O ₃ ), titanium oxide (TiO ₂ ) or the like having an average particle diameter of about 1 to 2 μm, and an average particle diameter of 1 to 2 A glass powder made of borosilicate glass or the like of about 2 μm is prepared, and these are mixed at an appropriate mixing ratio, for example, a weight ratio of 1: 1. Next, a suitable binder (binder), a plasticizer, an organic solvent (dispersant), etc. are added to the obtained mixed powder, and a slurry is obtained by mixing and stirring. Here, polyvinyl butyral is preferably used as the binder, but it is insoluble in water and easily dissolved or swelled in a so-called oil-based organic solvent. Next, the obtained slurry is formed into a sheet on a PET film using a doctor blade, reverse coater, etc., and formed into a sheet having a thickness of several μm to several hundred μm depending on the production conditions of the product. Take up on a roll.

Subsequently, the sheet is cut according to the use of the product, and further cut into a sheet having a predetermined size. In this embodiment, for example, it is cut into a square shape having a side length of 200 mm. Next, a through hole is formed at a predetermined position by drilling with a CO ₂ laser, a YAG laser, a mechanical punch or the like as required. Then, by filling the through hole with a thick film conductive paste in which metal particles are dispersed, a portion to be a contact (conductor post) is formed. In this way, a ceramic green sheet is obtained. Note that the liquid material 10 can be used as the thick film conductive paste.

  Next, the liquid material 10 is transferred from the nozzle 261 of the inkjet head 2 to a plurality of microdroplets D1 or droplets D while selecting and switching the discharge method from the first and second discharge methods by controlling the voltage application unit 4. The liquid material 10 is supplied to the substrate S shape. By supplying the liquid material 10 to the base material S, the first and second moving means 61 and 62, the linear motor 51, and the motors 52, 53, 54, and 55 are driven as necessary, and the ink jet head. 2 and the substrate S are moved relative to each other, whereby the liquid material 10 is supplied to a predetermined portion of the substrate S, and the conductor pattern precursor 200 is formed on the substrate S.

Here, as described above, the liquid material 10 is preferably supplied to the linear portion of the conductor pattern precursor 200 such as wiring by the second ejection method. As a result, a narrower and narrower wiring can be formed, and the distance between adjacent wirings can be further shortened.
Moreover, it is preferable that the liquid material 10 is supplied to the planar portions of the conductor pattern precursor 200 such as terminals by the first discharge method. Thereby, a uniform terminal with a thin film thickness can be formed. Therefore, the unevenness | corrugation of the terminal surface is suppressed and a terminal and what is connected to it can be connected more reliably. Further, since the electric resistance can be made uniform over the entire area of the terminal, the electrical characteristics of the conductor pattern are improved. Further, since the fine droplets D1 are uniformly distributed over a relatively wide range on the substrate S (a wide range as compared with the second ejection method), the terminals can be formed in a shorter time. it can.

After the conductor pattern precursor 200 is formed in this way, the required number of substrates S (for example, about 10 to 20) on which the conductor pattern precursor 200 is formed is manufactured by the same process. Next, the PET film is peeled off from these substrates S, and these are laminated. At this time, about the base material S to laminate | stack, it arrange | positions so that each conductor pattern precursor 200 may connect via a contact between the base materials S piled up and down as needed. Then, each base material S is crimped | bonded, heating to the glass transition point or more of the binder which comprises the base material S. FIG. Thereby, the laminated body 300 is obtained.
When the laminated body 300 is formed in this way, for example, heat treatment is performed by a belt furnace or the like. Thereby, each base material S becomes a wiring board by being sintered, and the conductor pattern precursor 200 is a circuit (conductor) composed of a wiring pattern or an electrode pattern by sintering silver colloidal particles constituting it. Pattern).

  Here, the heating temperature of the laminated body 300 is preferably set to be equal to or higher than the softening point of the glass contained in the substrate S, and specifically, is preferably set to 600 ° C. or more and 900 ° C. or less. As heating conditions, the temperature is raised and lowered at an appropriate rate, and the maximum heating temperature, that is, the temperature of 600 ° C. to 900 ° C. is maintained for an appropriate time according to the temperature. To do.

Thus, the glass component of the obtained ceramic substrate can be softened by raising the heating temperature to a temperature equal to or higher than the softening point of the glass, that is, the temperature range. Therefore, after cooling to room temperature and hardening the glass component, the ceramic substrate constituting the laminated substrate and the circuit are more firmly fixed.
Moreover, by heating in such a temperature range, the obtained ceramic substrate becomes a low temperature sintered ceramic (LTCC) formed by sintering at a temperature of 900 ° C. or lower.

Here, the metals in the liquid material 10 disposed on the base material S are fused with each other by heat treatment and become conductive by being continuous.
By such heat treatment, the circuit is formed by being directly connected to the contact in the ceramic substrate and made conductive. Here, if the circuit is merely placed on the ceramic substrate, the mechanical connection strength to the ceramic substrate is not ensured, and therefore, there is a possibility that the circuit is damaged by an impact or the like. However, in this embodiment, as described above, the circuit is firmly fixed to the substrate S by once softening the glass in the substrate S and then curing the glass. Therefore, the formed circuit has a high mechanical strength.
As mentioned above, although the droplet discharge method and the droplet discharge device of the present invention have been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is arbitrary as long as it has the same function. It can be replaced with that of the configuration. In addition, any other component may be added to the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Droplet discharge device 10 ... Liquid material 2 ... Inkjet head 21 ... Head body 211 ... Reservoir 212 ... Ink chamber 22 ... Vibration plate 23 ... Piezo element 24 ... Drive circuit 26 ... Nozzle Plate 261 ... Nozzle 3 ... Table 31 ... Electrode 4 ... Voltage application means (potential difference generating means) 51 ... Linear motor 52 ... Motor 53 ... Motor 54 ... Motor 55 ... Motor 61 ... First Moving means 62 ... Second moving means 100 ... Control device 200 ... Conductor pattern precursor 300 ... Laminated body D ... Droplet D1 ... Micro droplet E ... Electric field S ... Substrate (acceptor)

Claims (13)

  A droplet discharge head for discharging a liquid material having charging properties as droplets from a nozzle formed on a nozzle plate having conductivity; and an electrode disposed opposite to the droplet discharge head and the discharge direction of the liquid material. A receptacle for supplying the liquid material discharged from the droplet discharge head is disposed between the nozzle plate and the electrode, and the liquid material is formed as droplets from the nozzle in a state where a potential difference is generated between the nozzle plate and the electrode. A first discharge method in which the droplet is supplied to the receptor in the form of a mist divided into a plurality of micro droplets smaller than the droplet by discharging; and a potential difference between the nozzle plate and the electrode A droplet discharge method, wherein the second discharge method is selected such that a droplet of the liquid material discharged from the nozzle is supplied to the receptor.   In the first ejection method, the liquid material droplet ejected from the nozzle is charged in a potential space generated between the nozzle plate and the electrode, and the electrostatic repulsive force generated by the charging causes the liquid material droplet to be charged. The droplet discharge method according to claim 1, wherein the droplet discharge method is divided into a plurality of minute droplets.   3. The droplet discharge method according to claim 1, wherein in the first discharge method, the liquid material droplet discharged from the nozzle has a charge repulsive force acting on the droplet larger than a surface tension. In the first ejection method, the surface tension acting on the liquid material droplet ejected from the nozzle is T, the charge amount of the droplet is Q, the radius of the droplet is R, and the dielectric constant of the vacuum The droplet discharge method according to claim 3, wherein the relationship T ≦ Q ² / 64π ² ε ₀ R ³ is satisfied, where ε is ε ₀ and the circumferential ratio is π. 5. The droplet discharge method according to claim 3, wherein the liquid material has an electric conductivity of 1 × 10 ⁻¹² S / m or more and 1 × 10 ⁻² S / m or less.   6. The droplet discharge method according to claim 1, wherein in the second discharge method, the liquid material droplet discharged from the nozzle has a charge repulsive force acting on the droplet smaller than a surface tension. .   The droplet discharge head includes a cavity filled with the liquid material and communicated with the nozzle, and a pressure generating unit that changes the pressure in the cavity, and the piezoelectric element is driven to drive the piezoelectric element from the nozzle. The droplet discharge method according to claim 1, wherein the liquid material is discharged.   8. The droplet discharge method according to claim 1, wherein in the first discharge method, an average droplet diameter of the minute droplets is 1 nm or more and 10 μm or less.   The landing area of the droplets discharged by the first discharge method on the receptor is larger than the landing area of the droplets discharged by the second discharge method on the receptor. The droplet discharge method described.   The droplet discharging method according to claim 1, wherein the liquid material is a liquid material for forming a wiring for forming a conductor pattern on the receptor.   For the wiring that forms the conductor pattern formed on the receptor, the liquid material is supplied by the second supply method, and for the terminal that has a planar shape, the liquid material is supplied by the first supply method. The droplet discharge method according to claim 10.   The droplet discharging method according to claim 10 or 11, wherein the liquid material is obtained by dispersing metal particles in a dispersion medium. A droplet discharge head for discharging a liquid material having charging properties as droplets from nozzles formed on a nozzle plate having conductivity;
An electrode disposed opposite to the liquid droplet ejection head in the liquid material ejection direction;
A potential difference generating means for generating a potential difference between the nozzle plate and the electrode;
By discharging the liquid material as droplets from the nozzle in a state in which a potential difference is generated between the nozzle plate and the electrode by the potential difference generating means, the droplet is made into a plurality of microscopic droplets smaller than the droplet. A first discharge method for supplying a receiver disposed between the droplet discharge head and the electrode in the form of a mist divided into droplets; and a potential difference between the nozzle plate and the electrode. A liquid having a smaller state than that of the first discharge method and capable of selecting a second discharge method for supplying the liquid material droplets discharged from the nozzle to the receiver without being divided into mists. Drop ejection device.

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