JP2012057036A - Method of preparing ink and pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably remove an aggregate of nano-particles from an ink, thereby forming a pattern excellent in functionality.SOLUTION: A method of preparing the ink containing the nano-particles includes: centrifuging the ink; and removing the aggregate of the nano-particles.

Description

  The present invention relates to an ink preparation method and a pattern formation method.

Conventionally, a method of forming a pattern such as a fine wiring pattern by a printing method has been proposed.
Specifically, a pattern is formed by patterning nano ink containing a pattern forming material as nanoparticles having a particle diameter of 1 μm or less on a substrate as an ink, and baking the patterned ink.

  In recent years, attempts have been made to form a fine pattern having a line width of about 10 μm by the above printing method. However, the nanoparticles contained in the ink may be aggregated. When a fine pattern is formed using ink containing such an aggregate, the shape of the aggregate remains in the pattern, and the surface of the pattern is not smooth, and a protruding portion is generated.

Such protrusions are desirably eliminated because they lead to deterioration of pattern functions such as deterioration of conductivity.
For this reason, Patent Documents 1 and 2 propose techniques for dispersing nanoparticle aggregates.

JP 2006-312130 A Japanese Patent Laid-Open No. 2005-5198 JP 2004-319172 A

However, even when the above-described method for dispersing the aggregates of nanoparticles was used, the projections on the pattern surface could not be sufficiently eliminated.
This is presumably because the protective colloid coated on the nanoparticles in order to prevent fusion is peeled off during the transporting process and the nanoparticles are fused. Since the nanoparticles thus fused are integrated by fusion, they cannot be dispersed by a method of dispersing an aggregate of nanoparticles.

  In addition, as shown in Patent Document 3, proposals have been made to remove aggregates such as aggregates and fusion bodies of nanoparticles by filtering ink, but the aggregates of nanoparticles are sufficiently removed. The projection on the pattern surface could not be eliminated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to more reliably remove an aggregate of nanoparticles from an ink and thereby form a pattern having excellent functionality.

  The present invention adopts the following configuration as means for solving the above-described problems.

  A first invention is a method for preparing an ink containing nanoparticles, and employs a configuration in which the ink is centrifuged to remove the aggregate of the nanoparticles.

  According to a second aspect of the present invention, in the first aspect of the present invention, a configuration is adopted in which the rotation speed and time of the centrifugal separation are set according to the viscosity of the ink.

  The third invention adopts a configuration in which the viscosity of the ink is adjusted prior to the centrifugation in the second invention.

  A fourth invention is the ink according to any one of the first to third inventions, wherein the supernatant of the ink after centrifugation is collected as a prepared ink, and the remaining liquid is centrifuged again to prepare the supernatant. The configuration of collecting as is adopted.

  According to a fifth aspect of the present invention, there is provided a patterning step of patterning an ink prepared by the ink preparation method according to any one of the first to fourth aspects of the invention on a substrate, and the ink disposed on the substrate in the patterning step. A configuration is adopted in which a baking process is performed to form a pattern by baking.

  In a sixth aspect based on the fifth aspect, the patterning step includes an inking step for filling the concave portion of the intaglio with the ink, and a acceptance step for accepting the ink filled in the concave portion of the intaglio with a blanket. And a transfer step of transferring the ink received by the blanket onto a substrate.

  According to the present invention, the aggregate of nanoparticles is removed by centrifugation. As a result, it is possible to remove the aggregate of nanoparticles than in the past, and it is possible to form a pattern with no protrusions on the surface and having excellent functionality.

It is a flowchart of the pattern formation method in one Embodiment of this invention. It is a schematic block diagram of the printing apparatus used with the pattern formation method in one Embodiment of this invention. It is a block diagram which shows the electrical connection of the printing apparatus used with the pattern formation method in one Embodiment of this invention. It is the microscope picture of the fine pattern formed with the fine pattern formed with the conventional method, and the pattern formation method in one Embodiment of invention.

  Hereinafter, an embodiment of an ink preparation method and a pattern formation method according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

FIG. 1 is a flowchart of a pattern forming method in the present embodiment.
As shown in this figure, the pattern forming method in the present embodiment includes a centrifugation step S1, a patterning step S2, and a baking step S3.

  Centrifugation step S1 is a step of preparing ink using the ink preparation method of the present invention, and is a step of removing an aggregate of nanoparticles previously contained in the ink by centrifuging the ink.

  More specifically, the ink is centrifuged by, for example, a horizontal rotor type or an angle rotor type centrifuge. As a result, the weight of the aggregate in which the nanoparticles are gathered moves away from the center of rotation of the centrifuge. For this reason, the supernatant liquid after centrifugation does not contain an aggregate of nanoparticles, and this supernatant liquid is recovered as a prepared ink.

  As the ink, for example, a silver nano ink in which the nanoparticles are silver particles and the dispersion medium is alcohol can be used. However, the present invention is not limited to this, and the target nanoparticles are inks including one or more of copper particles, ITO (indium tin oxide) particles, tin particles, silicon particles, alloy particles, and the like. Can do. Furthermore, the ink dispersion medium is not limited to an alcohol type, and may be an aqueous type or an organic solvent type.

  The aggregate of nanoparticles in the present embodiment is not limited to a fused body in which nanoparticles are fused, but includes an aggregate in which nanoparticles are aggregated.

In the present embodiment, the rotation speed and time of the centrifugation are set according to the viscosity of the ink.
The sedimentation (separation) time T of the particles in the centrifugation is expressed by the following formula (1).

Note that in (1), K represents the K factor, the following equation (2), S represents a value obtained by ^{10 13} fold compared constants, represented by the following formula (3).

Here, in Equation (2), N is the number of rotations during centrifugation, Rmax is the maximum rotation radius of the centrifuge tube, and Rmin is the minimum rotation radius of the centrifuge tube.
In equation (3), d is the diameter of the particle diameter (an aggregate of nanoparticles to be removed), σ is the density of the particle, ρ is the density of the solution, and η is the viscosity of the solution.

  As can be seen from the equations (1) to (3), the rotation and time of the centrifugal separation use the viscosity of the ink as a parameter. Therefore, the rotation speed and time of the centrifugation can be set according to the viscosity of the ink.

In addition, since the rotation speed in the centrifuge is limited, if the viscosity is too high, as can be seen from the formulas (1) to (3), a very long time is required to remove the aggregate of nanoparticles. turn into.
For this reason, if it is only for shortening the time required for centrifugation, it is so preferable that the viscosity of an ink is low.

However, inks that are too low in viscosity cannot be patterned using printing methods. That is, the ink having a too low viscosity cannot be used in the subsequent patterning step S2.
For this reason, it is preferable that the viscosity of the ink is as low as possible within a range that can be patterned using a printing method.

  Therefore, it is preferable to adjust the viscosity of the ink prior to centrifugation. Specifically, the viscosity of the ink can be adjusted by adjusting the amount of the dispersion medium of the ink. For example, the viscosity of the ink decreases by adding the dispersion medium, and the viscosity of the ink can be increased by volatilizing the dispersion medium.

  The viscosity at which the centrifugation time is 1 hour and the pattern can be formed by the printing method is 0.1 (Pa · s) to 1 (Pa · s).

As described above, the supernatant liquid after centrifugation is recovered as a prepared ink. However, all particles contained in the residual liquid are not aggregates of nanoparticles, and the residual liquid contains It contains single nanoparticles that are not aggregated.
For this reason, it is preferable to centrifuge the residual liquid again and collect the supernatant liquid as a prepared ink. Thus, the efficiency of ink use can be increased by performing centrifugal separation a plurality of times.

  Patterning process S2 and baking process S3 are the processes of forming a pattern by the gravure offset printing method which is one of the printing methods using the ink after preparation. In the case of forming a pattern by the gravure offset printing method, it is preferable to use an organic solvent-based dispersion medium because the water-based dispersion medium is not compatible with a blanket described later.

  The patterning step S2 is a step of patterning the ink on the substrate after the centrifugation step S1 performed using the above-described ink preparation method. As shown in FIG. 1, the inking step S2a and the receiving step S2b are performed. And a transfer step S2c.

The inking step S2a is a step of filling the concave portions of the intaglio with the ink prepared in the centrifugal separation step S1.
The accepting step S2b is a step in which the blanket accepts the ink filled in the concave portion of the intaglio.
The transfer step S2c is a step of transferring the ink received by the blanket onto the substrate.

FIG. 2 is a schematic configuration diagram of the printing apparatus S for performing the patterning step S2. FIG. 3 is a block diagram showing electrical connections of the printing apparatus S.
As shown in FIGS. 2 and 3, the printing apparatus S of the present embodiment includes a gantry 1, an intaglio stage apparatus 2, a substrate stage apparatus 3, an inking apparatus 4, a transfer apparatus 5, and an alignment apparatus 6. And a control device 7 (not shown in FIG. 2).

On the upper surface of the gantry 1, a rail 10 that is shared by the intaglio stage device 2 and the substrate stage device 3 is laid and supports the inking device 4, the transfer device 5, and the alignment device 6 along the rail 10. is doing.
In the following description, the extending direction of the rail 10 is described as the X direction, and the vertical direction orthogonal to the X direction is described as the Z direction.

  The intaglio stage device 2 supports an intaglio X having a recess corresponding to the ink pattern, and moves the intaglio X in the X direction. A linear device 2a using the rail 10 as a stator, an intaglio stage 2b, It has. In the present embodiment, the intaglio X has a flat plate shape.

  The linear device 2 a includes a rail 10 and a moving element 2 a 1 that moves by electromagnetic induction along the rail 10. Under the control of the control device 7, the moving element 2 a 1 is placed at an arbitrary position with respect to the rail 10. It can be moved.

  The intaglio stage 2b is mounted with the intaglio X and is fixed to the mover 2a1 of the linear device 2a, and is movable in the X direction by the movement of the mover 2a1.

  The substrate stage device 3 supports the substrate Y on which ink is patterned, and moves the substrate Y in the X direction. The substrate stage device 3 includes a linear device 3a using the rail 10 as a stator, and a substrate stage 3b. Yes.

  The linear device 3 a includes a rail 10 and a mover 3 a 1 that moves by electromagnetic induction along the rail 10. Under the control of the control device 7, the mover 3 a 1 is placed at an arbitrary position with respect to the rail 10. It can be moved.

  The substrate stage 3b is fixed to the moving element 3a1 of the linear device 3a on which the substrate Y is installed, and is movable in the X direction by the movement of the moving element 3a1.

  The inking device 4 disposes ink in the concave portion of the intaglio X moved by the intaglio stage device 2, and includes a plurality of doctor blades 4a, a lifting device 4b provided for each doctor blade 4a, And an ink supply device 4c.

The doctor blade 4a moves the ink arranged on the intaglio X on the intaglio X, a pushing blade 4a1 that pushes the ink into the concave portion of the intaglio, and a scraping blade 4a2 that scrapes off excess ink. And a return blade 4a3 for returning the ink to the initial position.
These doctor blades 4a are arranged at an inclination angle at which the lower end slides on the upper surface of the intaglio X to move the ink and achieve the above functions.

  The lifting device 4b lifts and lowers the doctor blade 4a under the control of the control device 7. The lifting blade lifting device 4b1 lifts and lowers the pushing blade 4a1, and the scraping blade 4a2 lifts and lowers the scraping blade lifting device 4b2. It is comprised by the return blade raising / lowering apparatus 4b3 which raises / lowers the return blade 4a3.

  The ink supply device 4c discharges ink onto the intaglio X at the front stage of the doctor blade 4a.

  The transfer device 5 receives the ink pattern formed by filling the concave portion of the intaglio X from the intaglio X and transfers it to the substrate Y, thereby patterning the ink on the substrate Y. The blanket A roll 5a (a blanket), a rotating device 5b, and an elevating device 5c are provided.

  The blanket roll 5a is a cylindrical member that receives ink by contacting the intaglio X and transfers ink by contacting the substrate Y, and includes a core portion 5a1 and a blanket cushion 5a2.

The core 5a1 is a part that is directly moved by the rotating device 5b and the lifting device 5c, and has a cylindrical shape.
The blanket cushion 5a2 is wound around the peripheral surface of the core part 5a1 with a material softer than the core part 5a1, and is bonded to the core part 5a1.

The rotation device 5b rotates the blanket roll 5a under the control of the control device 7, and is configured such that the rotation angle and rotation direction of the blanket roll 5a can be arbitrarily set.
The lifting device 5 c moves the blanket roll 5 a up and down (Z direction) under the control of the control device 7.

  The alignment device 6 captures an image of the intaglio X or the substrate Y, detects the amount of deviation between the intaglio X and the substrate Y from the imaged result, and includes a plurality of image sensors 6a.

  The control device 7 controls the entire operation of the printing device S of the present embodiment. As shown in FIG. 3, the intaglio stage device 2, the substrate stage device 3, the inking device 4, the transfer device 5, and the alignment device. 6, the ink is patterned on the substrate Y by controlling each of these electrically connected devices.

  In the printing apparatus S of the present embodiment configured as described above, ink is patterned on the substrate Y under the control of the control device 7. Specifically, first, the intaglio X is set on the intaglio stage 2b of the intaglio stage apparatus 2, and ink is applied onto the intaglio X by the ink supply device 4c.

Subsequently, an ink pattern is formed by filling the recesses of the intaglio X with ink.
More specifically, first, ink is pushed into the concave portion of the intaglio X by the pushing blade 4a1 of the inking device 4, and then the ink protruding from the concave portion of the intaglio X is scraped by the scraping blade 4a2 to form the concave portion. Push outside the area. As a result, ink is disposed only in the recesses of the intaglio X, and an ink pattern is formed.

Subsequently, the ink patterned by the intaglio X is received by the transfer device 5.
More specifically, the intaglio X in which the ink is disposed in the concave portion is conveyed to the transfer device 5 by the intaglio stage device 2. Then, when the blanket roll 5a is rotated in synchronization with the movement of the intaglio X while the silicon blanket 20 is pressed against the intaglio X, the ink moves from the intaglio X to the blanket roll 5a, thereby patterning on the intaglio X. The completed ink is received on the surface of the silicon blanket 20.

  The intaglio X after the ink is received by the transfer device 5 is returned again to the inking device 4 by the intaglio stage device 2, and the ink brought to one end side is returned to the initial position by the return blade 4a3. After that, it waits at the ink supply position.

Subsequently, the ink received by the transfer device 5 is transferred to the substrate Y.
More specifically, the substrate Y is transported to the transfer device 5 by the substrate stage device 3. Then, when the blanket roll 5a is rotated in synchronization with the movement of the substrate Y while the silicon blanket 20 is pressed against the substrate Y, the ink moves from the blanket roll 5a to the substrate Y, thereby the surface of the silicon blanket 20 Then, the patterned ink is transferred to the surface of the substrate Y.

  Returning to FIG. 1, the baking step S3 is a step of baking the substrate Y on which the ink has been patterned in the patterning step S3 in a baking furnace to evaporate the ink dispersion medium, thereby forming a pattern.

  According to such a pattern forming method, a wiring pattern can be formed by using conductive nanoparticles as ink.

  Then, according to the ink preparation method used in this embodiment, the aggregate of nanoparticles is removed by centrifugation. As a result, it is possible to remove the aggregate of nanoparticles than in the past, and it is possible to form a pattern with no protrusions on the surface and having excellent functionality.

  FIG. 4 shows a fine pattern (wiring pattern with a line width of 12 μm) formed by a conventional pattern forming method in which the pattern forming ink is not centrifuged, and a fine pattern formed by the pattern forming method of this embodiment. It is the photograph for comparing with a pattern, (a) is a photograph of the fine pattern formed by the conventional method, (b) is a photograph of the fine pattern formed by the pattern formation method of this embodiment. is there. In the drawing, black portions indicate between fine patterns, and gray portions indicate fine patterns. Further, in FIG. 4A, all black dots visible on the fine pattern are protrusions of 1 μm or more.

When the photograph shown in FIG. 4 is taken, in the pattern forming method of the present embodiment, alcohol-based silver nanoink is used as the ink, and the viscosity of the silver nanoink is adjusted to 0.5 (Pa · s). Using a horizontal rotor type centrifuge, the rotation speed was 5000 rpm, the operation time was 1 h, and the supernatant liquid (1.5 to 3.0 ml) after centrifugation was recovered.
In the conventional method, the same process as the pattern forming method of the present embodiment is performed except that the ink is not centrifuged.

As shown in FIG. 4, in the conventional method, a plurality of protrusions of 1 μm or more are formed on the fine pattern, but according to the pattern forming method of the present embodiment, the protrusions of the fine pattern can be completely eliminated. did it.
In addition, even when the centrifugal separation was performed using an angle rotor type centrifugal separator at a rotational speed of 15000 rpm and an operation time of 1 h, a fine pattern having no protrusions could be formed as shown in FIG. .

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the method for patterning the adjusted ink by the gravure offset printing method has been described.
However, the present invention is not limited to this. The adjusted ink can be used for other printing methods (for example, letterpress printing method).

Further, in the above-described embodiment, a configuration in which ink is used for forming a wiring pattern has been described.
However, the present invention is not limited to this, and can also be applied to the preparation of ink used for forming other functional patterns.

Moreover, in the said embodiment, the structure in which the intaglio X had a flat plate shape in the printing apparatus S was demonstrated.
However, the present invention is not limited to this, and it is also possible to use a cylindrical intaglio.

  DESCRIPTION OF SYMBOLS 1 ... Stand, 2 ... Intaglio stage device, 3 ... Substrate stage device, 4 ... Inking device, 5 ... Transfer device, 5a ... Blanket roll (blanket), 6 ... Alignment device, 7 ... Control device, S ... Printing device, X ... Intaglio, Y ... Substrate

Claims (6)

A method for preparing an ink comprising nanoparticles, comprising:
A method for preparing an ink, wherein the ink is centrifuged to remove the aggregate of nanoparticles.   2. The ink preparation method according to claim 1, wherein the rotation speed and time of the centrifugal separation are set according to the viscosity of the ink.   3. The ink preparation method according to claim 2, wherein the viscosity of the ink is adjusted prior to the centrifugation.   The supernatant liquid of the ink after centrifugation is collected as a prepared ink, and the residual liquid is centrifuged again to collect the supernatant liquid as a prepared ink. Ink preparation method. A patterning step of patterning the ink prepared by the ink preparation method according to claim 1 on a substrate;
And a baking step for forming a pattern by baking the ink disposed on the substrate in the patterning step. The patterning step includes
An inking step of filling the concave portion of the intaglio with the ink,
A receiving step in which a blanket receives the ink filled in the concave portion of the intaglio;
The pattern forming method according to claim 5, further comprising: a transfer step of transferring the ink received by the blanket onto a substrate.