KR20230050594A - Pen Nib Printing Methods And Apparatus For The Same - Google Patents

Abstract

Disclosed is a print electronic technology of a pen nip type. The present invention, in a method for printing a pattern by a capillary pen comprising a pen nip for contacting a printing surface and an ink chamber connected to the pen nip and accommodating an ink, provides the method for printing the pattern by the capillary pen comprising: a step of forming a meniscus of liquid ink by contacting the pen nip of the capillary pen with a printing surface; and a step of printing a pattern corresponding to a trajectory of the capillary pen by moving the printing surface while the pen nip of the capillary pen is in a contact state with the printing surface. Therefore, the present invention is capable of printing a precise pattern.

Description

Pen nib-based printing method and device thereof {Pen Nib Printing Methods And Apparatus For The Same}

The present invention relates to printed electronics technology, and more particularly to pennip type printed electronics technology.

Compared to the complicated and expensive conventional photolithography, printed electronics have the advantage of simplifying the process by directly printing a desired shape and producing fast and inexpensive circuit elements on various substrates.

In particular, as interest in the development of flexible and stretchable electronic technologies increases, there is an increasing demand for technologies capable of effectively implementing them. As a result, more and more attention is paid to discovering and developing technology elements closely related to flexible electronic devices (e.g., substrates, conductive materials, and manufacturing techniques) to manufacture electronic devices with improved performance and reduced cost. However, the development of fast and cost-effective manufacturing strategies for the implementation of flexible and stretchable electronics is attracting attention.

Until now, various technologies such as coating, sputtering, gravure printing, flexo printing, offset printing, inkjet printing, screen printing, etc. have been developed for manufacturing flexible electronic devices, but these sophisticated technologies have long coating processing times and high energy consumption of sputtering. and the inevitability of using expensive specialized equipment, etc., it may not be able to meet the new demand for low cost, easy accessibility and rapid fabrication for flexible electronic device manufacturing.

Recently, as a solution in this respect, various results have been reported in which various types of writing pens such as brushes, nibs (pen nibs), and ballpoint pens are used as substitute parts that discharge ink instead of existing nozzles. This strategy provides a simple, inexpensive and fast way to print functional parts to manufacture electronic devices.

However, pen-based printing to date has technical limitations in that the viscosity range of usable ink is fixed according to the type of pen and the line width of the pattern cannot be controlled.

(1) Z. L, Hao et al, "Recent Advances in Pen-Based Writing Electronics and their Engineering Applications", Adv. Funct. Mater. 2016, 26, 165-180 (2) B. Kang et al, "Directly Drawn Organic Transistors by Capillary Pen: A New Facile Patterning Method using Capillary Action for Soluble Organic Materials", Adv. Mater. 2013

In order to solve the problems of the prior art, an object of the present invention is to provide a pennip-based printing method capable of controlling the line width of a printed pattern by controlling the amount of ink ejected in the printing process.

In addition, an object of the present invention is to provide a pennip-based printing method capable of extending the viscosity range of printable ink.

Another object of the present invention is to provide a pennip-based printing method capable of controlling the line width of a printed pattern by applying a negative pressure and/or a positive pressure to ink.

In order to achieve the above technical problem, the present invention provides a pattern printing method using a capillary pen, which includes a pennip for contacting a printing surface and an ink chamber connected to the pennip and accommodating ink, wherein the capillary pen forming a meniscus of the liquid ink by contacting the pen nib of the pen nib with the printing surface; and printing a pattern corresponding to the trajectory of the capillary pen by moving the printing surface while the pen nib of the capillary pen is in contact with the printing surface. to provide.

In the present invention, the pen nip may include one or more capillary channels extending between a front end in contact with the printing surface and a rear end connected to the ink chamber. At this time, the capillary channels may be arranged in a net shape or arranged in parallel.

In the printing step of the present invention, back pressure may be applied to the ink in the ink chamber.

In addition, when the ink is a Newtonian fluid or a low-viscosity (1 to 100 mPa·sec) fluid-like fluid, the back pressure applied to the ink may be a negative pressure. At this time, the negative pressure may be 1 to 5 kPa.

Further, when the ink is a fluid-like behavior fluid with high viscosity (100 mPa·sec or more), the back pressure may be a positive pressure. At this time, the positive pressure may be 5 ~ 500 kPa.

In addition, the present invention may further include plating the printed pattern.

In the present invention, the line width of the printed pattern may be 10 to 500 μm.

In order to achieve the above other technical problem, the present invention provides a pen nip including a single or a plurality of capillary channels extending between a front end in contact with the printing surface and a rear end connected to the ink chamber; an ink chamber connected to the pennip and accommodating ink; and an ink back pressure adjusting mechanism for applying a back pressure to the ink in the ink chamber.

In the present invention, the ink back pressure adjusting mechanism may include a pneumatic pump.

At this time, the ink back pressure adjusting mechanism may apply a negative pressure to the ink.

In the pennip of the present invention, the capillary channels may be arranged in a net shape or in parallel.

According to the present invention, it is possible to provide a pennip-based printing method capable of controlling the line width of a printed pattern by controlling the amount of ink ejected during the printing process. In addition, according to the present invention, it is possible to expand the viscosity range of printable ink by applying negative/positive pressure to the ink, and it is possible to control the line width of the printed pattern. Specifically, by applying negative pressure to the ink, the line width of the pattern can be reduced. This makes it possible to print precise patterns.

1A to 1C are diagrams schematically illustrating a capillary pen-based printing technique according to an embodiment of the present invention.
Figure 2a is a view for explaining the behavior of ink discharged through the pennip according to the back pressure of the ink in the present invention.
2B is a diagram for explaining the behavior of ink when it comes into contact with a printing surface.
3a and 3b are graphs showing the flow characteristics of ink prepared according to an embodiment of the present invention.
4A and 4B are graphs showing flow characteristics of ink prepared according to another embodiment of the present invention, respectively.
Figure 5a is a photograph of observing the behavior of ink droplets according to the back pressure.
5B is a photograph showing the behavior of the ink meniscus according to the back pressure.
6 is a graph showing the results of measuring the line width of a printed pattern according to an embodiment of the present invention.
7 is a photograph of a grid pattern printed according to another embodiment of the present invention.
8 is a photograph of a state in which thermochromic ink is printed according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention.

1A is a diagram for schematically explaining a capillary pen-based printing technique according to an embodiment of the present invention.

Referring to FIG. 1A , a capillary pen 100 includes a pen nib 110 contacting a printing surface 10 at an end, an ink chamber 120 connected to the pen nib and accommodating ink 130, and the ink chamber It includes an ink back pressure adjusting mechanism 150 for adjusting the pressure of ink inside.

The pen nip 110 may be, for example, a thin columnar structure extending in the longitudinal direction of the capillary pen. The pen nip 110 has one or more capillaries connected to the ink chamber 120 inside the structure between the front and rear ends of the pen nip 110, and the ink in the chamber 120 is supplied with the single or plurality of capillaries. Through it, it flows to the front end of the pennip and is discharged.

The ink back pressure adjusting mechanism 150 adjusts the discharge pressure of the ink contained in the ink chamber. For example, in the present invention, the ink back pressure adjusting mechanism 150 may provide positive pressure and negative pressure to the ink. In the specification of the present invention, positive pressure refers to a state in which a back pressure higher than atmospheric pressure is applied to the ink, and negative pressure refers to a state in which a back pressure lower than atmospheric pressure is applied to the ink. In the present invention, the ink back pressure adjusting mechanism 150 may be a pneumatic pump or a hydraulic pump.

1b and 1c are electron micrographs of the side and bottom of the pennip end of the capillary pen, respectively.

Referring to the drawing, it can be seen that a plurality of capillaries formed on the surface of the front end of the pennip. The capillary conduit or capillary channel extends from the front end of the pennip to the back end of the pennip on the opposite side. As shown, the capillary tubes may be connected to each other in a networked manner, but the present invention is not limited thereto. Illustratively, a plurality of capillary channels extending from the front end to the rear end of the pennip may be arranged parallel to each other.

For example, the capillary structure of the pennip may be formed using a fiber bundle or an open pore channel, or may be implemented using a ballast phenomenon by extruding molten plastic from a thin hole.

In the present invention, the diameter of the capillary tube formed in the pennip is preferably 5 to 30 μm.

Figure 2a is a view for explaining the behavior of ink discharged through the pennip according to the back pressure of the ink in the present invention.

As shown in FIG. 2A , the surface of the pennip is wetted by ink at the back pressure P ₀ in an unpressurized state, and ink droplets are formed. At this time, the wettability of the ink may be determined by the capillary force of the capillary channel and the surface tension of the ink on the surface of the pennip.

Here, if a negative pressure (P _n ) is applied to the inside of the ink chamber, the ink on the surface of the pennip is sucked into the inside of the pennip, and conversely, if a positive pressure (P _p ) is applied to the inside of the ink chamber, the ink is ejected.

In the present invention, the negative pressure of the ink may change according to the viscosity of the fluid, and preferably, the negative pressure may be designed differently according to the fluid. A low negative pressure can be used, for example, when the ink is a Newtonian fluid. On the other hand, in the case of ink exhibiting a fluid-like behavior of low viscosity (1 to 100 mPa·sec), a larger negative pressure than that of Newtonian ink can be applied. In the present invention, the preferred negative pressure range is preferably in the range of 1 to 5 kPa. In addition, the preferred positive pressure range in the present invention is preferably 5 to 500 kPa.

2B is a diagram for explaining the behavior of ink when a pen nib contacts a printing surface by writing pressure.

Referring to FIG. 2B , when writing pressure is applied in a state where the ink back pressure is zero (P ₀ ) and the pennip comes into contact with a printing surface such as a substrate, the ink droplet forms a meniscus between the surface of the pennip and the substrate. form At this time, the area where the ink meniscus contacts the substrate (A _m ) changes according to the amount of ink droplets (Q _i ). In addition, the amount of ink droplets (Q _i ) may affect printing continuity and line width (W _L ) of a printed pattern.

As shown in FIG. 2B, if a negative pressure (P _n ) is applied to the inside of the ink chamber, the ink is sucked into the pennip, and the contact area (Am) of the ink meniscus with the substrate is reduced. Conversely, the ink It can be seen that when a positive pressure (P _p ) is applied inside the chamber, the contact area of the ink meniscus with the substrate increases.

Hereinafter, preferred embodiments of the present invention will be described.

<Manufacture of ink>

A. Ag catalyst ink

Ag catalyst was prepared by mixing 0.5 g of silver nitrate (AgNO3, 99.8%, Daejung Chemicals & Metals Co., Ltd), 0.1 g of APTES (3-Aminopropyltriethoxysilane, 99%, Sigma-Aldrich), and 9.4 g of HPC (hydroxypropyl cellulose) aqueous solution. ink was prepared. HPC aqueous solution was prepared by mixing HPC (99%, Mw = 100,000, Sigma-Aldrich) and deionized water at a ratio of 1:93 in a vortex mixer (VM-10, Daihan Scientific Co.).

The prepared ink was analyzed for rheological properties using a rheometer. Flow characteristics of the prepared ink are shown in FIGS. 3a and 3b. As shown, the prepared Ag catalyst ink exhibits Newtonian behavior with a constant viscosity in the shown shear rate range.

B. Ag-PEDOT:PSS Ink

Ag-PEDOT:PSS ink was prepared by mixing 5 mg AgNO3 with 4.995 g PEDOT:PSS aqueous solution (aqueous solution in which 3.0-4.0 wt% PEDOT:PSS aqueous solution and PEDOT:PSS colloid were dispersed).

Flow characteristics of the prepared ink are shown in FIG. 4a. It can be seen that the prepared ink exhibits viscoelastic properties in which the viscosity changes in the shear rate range.

C. thermochromic pigment inks

Four types of pigment particles with different color transition temperatures (red: 50 °C, orange: 40 °C, yellow: 37 °C, and green: 33 °C) were prepared. A polyvinylpyrrolidone (PVP) aqueous solution was prepared by mixing 0.5 g PVP (Mw = 360,000, Sigma-Aldrich) and 4.35 g deionized water. By adding 0.15 g of pigment particles to the PVP aqueous solution, color-changing ink was prepared for each type of pigment particle.

Flow characteristics of the prepared ink are shown in FIG. 4B. It can be seen that the prepared ink exhibits viscoelastic properties in which the viscosity changes in the shear rate range.

<Pennip-based printing device>

The pennip was removed from the capillary pen (0.05 mm) and washed in deionized water for 30 minutes. The washed pennip was assembled into a 3mL syringe using a plastic Luer-lock.

In order to implement a multi-pennip printer head, a 3D plastic head capable of mounting 4 pennips was manufactured. The fluid dispenser was mounted in the center of the plastic head and pneumatics were applied.

The printer head produced by the 3-axis printing system was precisely controlled.

<Change of ink meniscus according to back pressure>

The behavior of ink droplets and ink meniscus according to back pressure was observed using Ag catalyst ink in the above-described pennip-based printing device.

Figure 5a is a photograph of observing the behavior of ink droplets according to the back pressure.

As shown in FIG. 5A , it can be seen that the size of the ink droplets decreases in the negative pressure (P _n ) state and increases in the positive pressure (P _p ) state compared to the no-pressure state (P ₀ ). At this time, P _n was set to about 4 kPa and Pp was set to 35 kPa.

5B is a photograph of the actual behavior of the ink meniscus according to back pressure. It can be seen that the contact area between the ink meniscus and the substrate increases in the positive pressure state, whereas the contact area between the ink meniscus and the substrate decreases in the negative pressure state.

<Production Example 1>

Using the Ag catalyst ink described above in a pennip-based printing device, a change in line width of a printed pattern according to back pressure was observed. At this time, the back pressure of the ink was changed to 2 kPa and 4 kPa as a negative pressure, and an FR4 substrate was used as the printing surface. After pattern printing, copper electroless plating (plating at 60 °C for 30 min) was applied to form a Cu pattern. On the other hand, in order to understand the effect of the pattern line width according to the sweep speed of the pennip, the sweep speed was changed to 40 mm/s, 80 mm/s, and 120 mm/s.

6 is a graph showing the results of measuring the line width of the plated copper pattern according to the back pressure of the ink. The picture on the right of FIG. 6 is a picture of the pattern line width according to the sweep speed of the pennip at a negative pressure of 2 kPa.

Referring to FIG. 6 , when the sweep speed increases from 40 mm/s to 120 mm/s in a non-pressurized state (P ₀ ), it can be seen that the line width decreases from about 187 μm to 49 μm. This is because an increase in the sweep speed decreases the contact area (A _m ) of the ink meniscus. On the other hand, it can be confirmed that the negative pressure (P _n ) also contributes to the reduction of the contact area (A _m ). At a negative pressure of about 2 kPa, the line width decreased to about 38 μm. In addition, although the minimum line width in this embodiment was 38 μm, it is of course possible to print a pattern having a minimum line width of 10 μm by controlling the surface tension of the ink.

The electrical conductivity of the Cu pattern prepared in this example was about 4.26 Х 107 S·m-1 (at 25 °C), which corresponds to about 76% of the bulk Cu electrical conductivity.

<Production Example 2>

Ag-PEDOT:PSS heater patterns were printed using the Ag-PEDOT:PSS ink described above in a pennip-based printing device. A flexible PET sheet was used as the substrate.

As shown in FIG. 4a, the Ag-PEDOT:PSS ink exhibits a shear-thinning behavior in which the viscosity decreases as the shear rate increases, and the storage modulus (G') is greater than the loss modulus (G"). Since the Ag-PEDOT:PSS ink exhibits a viscosity of about 650 mPa s (shear rate 1 s ^-1 ) when loaded in a syringe of a printing device, it exhibits a low fluid-like behavior, and therefore, capillary action Therefore, in this experiment, positive pressure (P _p ) was applied to the ink to print.

7 is a photograph of a grid pattern printed on a PET sheet using a positive pressure of 72 kPa. At this time, the positive pressure was 82.7 kPa (sweep speed v _t = 40 mm·s -1 ).

<Production Example 3>

Alphabets were printed on a hemispherical substrate by loading a pennip-based printing device with a syringe containing the four types of thermochromic inks described above. At this time, the sweep speed (v _t ) was 1 mm·s ^-1 , and Pp = 55.1 kPa.

8 is a photograph of a state in which thermochromic ink is printed. Referring to FIG. 8 , it can be seen that the thermochromic ink is uniformly applied on the 3D surface. In addition, as shown in the right picture of FIG. 8, the thermochromic ink has a transition temperature (33 °C (green), 37 °C (yellow), 40 °C (orange), and 50 °C (red)) It can be seen that it loses its own color and maintains the original ink properties.

In the above, the present invention has been described in detail through the embodiments of the present invention, but the above description is an illustration of the present invention, and the present invention is not limited thereto. Anyone with ordinary knowledge in the field to which the invention pertains without departing from the appended claims and the gist of the present invention should be considered to be within the scope of the present invention to the extent that various changes can be made.

100 capillary pen
110 pen nib
120 ink chamber
130 ink
150 ink back pressure adjustment mechanism

Claims (14)

A pattern printing method using a capillary pen comprising a pen nib for contacting a printing surface and an ink chamber connected to the pen nib and containing ink,
contacting the pen nib of the capillary pen to a printing surface to form a meniscus of liquid ink; and
and printing a pattern corresponding to the trajectory of the capillary pen by moving the printing surface while the pen nib of the capillary pen is in contact with the printing surface. According to claim 1,
The pen nip includes a plurality of capillary channels extending between a front end in contact with the printing surface and a rear end connected to the ink chamber. According to claim 1,
A pattern printing method using a capillary pen, characterized in that the capillary channels are arranged in a net shape or in parallel. According to claim 2,
A pattern printing method using a capillary pen, characterized in that back pressure is applied to the ink in the ink chamber. According to claim 3,
The ink is a Newtonian fluid,
The pattern printing method by a capillary pen, characterized in that the back pressure is negative pressure. According to claim 5,
The pattern printing method by a capillary pen, characterized in that the negative pressure is 1 to 5 kPa. According to claim 3,
the ink is a fluid with fluid-like behavior;
The pattern printing method by a capillary pen, characterized in that the back pressure is a positive pressure. According to claim 1,
The positive pressure is a pattern printing method by a capillary pen, characterized in that 5 ~ 500 kPa. According to claim 1,
The pattern printing method further comprising the step of plating the printed pattern. According to claim 1,
Pattern printing method, characterized in that the line width of the printed pattern is 40 μm or less. a pennip comprising a plurality of capillary channels extending between a front end in contact with the printing surface and a rear end connected to the ink chamber;
an ink chamber connected to the pennip and accommodating ink; and
and an ink back pressure adjusting mechanism for applying a back pressure to the ink in the ink chamber. According to claim 11,
The capillary pen-based printing device according to claim 1, wherein the ink back pressure regulating mechanism includes a pneumatic pump. According to claim 11,
The capillary pen-based printing device according to claim 1, wherein the ink back pressure adjusting mechanism applies a negative pressure to the ink. According to claim 11,
The capillary pen-based printing device, characterized in that the capillary channels are arranged in a net shape or arranged in parallel.

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