JP7776180B2 - Printing method and manufacturing method of electronic device - Google Patents

Description

The present invention relates to a printing method, a method for manufacturing an electronic device, and a porous member.

Technologies have been proposed for forming metal wiring for electronic components by applying metal nanoparticle ink to a substrate. For example, Patent Document 1 describes a technology in which ultraviolet light is irradiated onto the surface of a polymer layer formed on a substrate to form a reactive surface, and then metal nanoparticle ink is applied to that reactive surface to form a metal layer.

JP 2015-44373 A

However, the technology described in Patent Document 1 uses a blade to apply ink to a flat surface, and does not take into consideration applying ink to non-flat objects such as curved surfaces. Furthermore, the technology described in Patent Document 1 is significantly limited in the types of substrate surfaces and inks that can be used, leaving it with limited versatility.

The present invention was made in consideration of these circumstances, and one of its exemplary purposes is to provide a printing method, a manufacturing method for an electronic device, and a porous member that can easily produce a desired printing pattern.

In order to solve the above problem, a printing method of one embodiment of the present invention includes a member preparation step of preparing a porous member whose pores are filled with ink, an object preparation step of preparing a printing object having a pattern area formed on its surface, and an attachment step of adhering the ink filled in the pores to the pattern area by sweeping the porous member over the surface of the printing object.

Another aspect of the present invention is a method for manufacturing an electronic device using the above-mentioned printing method.

Another aspect of the present invention is a porous member. The porous member comprises a porous body having pores and a molecular modification film formed to cover the inner surfaces of the pores, and the pores have multiple openings and constitute the pore portions of the porous body.

In addition, any combination of the above components, and conversions of the present invention into methods, devices, systems, etc., are also valid aspects of the present invention.

The present invention makes it possible to easily create desired printing patterns.

1 is a diagram showing a schematic configuration of a printing member according to an embodiment of the present invention; 1 is a flowchart illustrating the flow of a printing method according to an embodiment of the present invention. 10A to 10C are diagrams illustrating an example of a film forming step according to the embodiment. FIG. 1 is a diagram for explaining the contact angle of a water droplet. FIG. 5(a) is a side view of a printing object according to one embodiment of the present invention, and FIG. 5(b) is a top view of a printing object according to one embodiment of the present invention. FIG. 6A is a diagram showing the state when the sweeping of the printing member starts, and FIG. 6B is a diagram showing the state after the sweeping of the printing member. FIG. 2 is a top view of an example of a print target after printing by the printing method according to the embodiment. 10A and 10B are diagrams showing the printed results of electrode wiring according to Example 1. FIG. 10 is a photograph showing the appearance of the surface of the printing object after printing in Example 2, observed with an optical microscope. FIG. 10 is a photograph showing the appearance of a print object after printing in Example 3. FIG. 10 is a diagram showing a printed result of wiring according to Example 4. FIG. 10 is a diagram showing a printing result of an organic semiconductor according to Example 5. Figure 13(a) is a diagram showing the surface of a printing object on which a pattern area according to Example 6 has been formed, and Figure 13(b) is a diagram showing the surface of the printing object after printing according to Example 6. FIG. 13 is a diagram showing a print result according to Example 7. FIG. 15 is a photograph of the surface of the printing object after printing in Example 8, observed with an optical microscope.

[background]
Toward a future society in which humans and computers are more comfortably connected, there is a strong demand for lightweight, flexible, and free-form information input/output devices. However, current processes such as photolithography lack the means to form wiring and electronic circuits on complex three-dimensional shapes, such as free-form curved surfaces. Furthermore, significant limitations exist not only in terms of shape but also in terms of resolution, such as the width of the wiring (also simply referred to as "line width"). These challenges present a challenge for realizing free-form devices. Here, a free-form shape refers to a shape that cannot be realized by bending or folding a flat surface, such as the shape of a computer mouse.

In addition, with the development of printed electronics, a method has been developed in which wiring patterns are formed by forming patterns with different surface free energies on the surface of a substrate and then applying ink (Supernap (registered trademark) method, hydrophilic-hydrophobic patterning method). However, the above issues have not yet been resolved, and there is a need to develop a "method and printing method for applying ink evenly to curved surfaces."

[Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted as appropriate. Furthermore, the configurations described below are examples and do not limit the scope of the present invention in any way.

Figure 1 is a diagram showing the schematic configuration of a printing member 10 according to one embodiment of the present invention. The printing member 10 according to this embodiment is a member used for printing on various printing objects. As shown in Figure 1, the printing member 10 comprises a porous member 100 and a supply member 140, and the porous member 100 and the supply member 140 are bonded to each other by an adhesive layer 120.

The porous member 100 is a member having a porous portion, and has a surface (hereinafter also referred to as the "opening surface") on which the openings of the porous portion are formed. For example, multiple openings may be formed on the bottom surface (opening surface 102) and side surface 104 of the porous member 100.

In this embodiment, the voids are filled with various known inks. The ink may be filled into the voids by, for example, seeping in through the openings. The ink may contain a conductive material, an organic semiconductor, or a ferroelectric. When producing a conductive pattern, the ink may contain various conductive materials. In this case, for example, the ink may be a dispersion of metal nanoparticles such as silver nanoparticles in a solvent, or may contain various metals such as gold, copper, and nickel, or may contain a conductive polymer. When producing an organic thin film pattern, the ink may contain various organic materials, such as organic semiconductors. Furthermore, various materials can be used as long as they can be made into ink, and in addition to the above inks, insulating inks can also be used.

The solvent may be a highly polar or a low-polarity solvent. The solvent may be any organic solvent, such as hydrocarbon solvents such as octane and hexane, aromatic hydrocarbon solvents such as xylene and toluene, or halogenated solvents such as chlorobenzene and chloroform. The solvent may also be water or alcohol-based solvents used in water-soluble inks. Furthermore, the solvent may be a mixture of these solvents, and the prepared ink may contain additives such as thickeners and surfactants.

The pore diameter of the pores is not particularly limited, but is preferably in the range of 50 nm to 3 mm. A pore diameter of 50 nm or greater allows ink to be easily filled into the pores. Furthermore, a pore diameter of 3 mm or less allows ink to be well retained in the pores, suppressing ink leakage. The pore diameter of the pores is more preferably in the range of 1 μm to 1000 μm, and even more preferably in the range of 10 μm to 200 μm. Furthermore, the larger the pore diameter of the pores, the more uneven and rough the surface of the porous member 100 becomes, and this disruption of flatness may cause defects such as scratches on the printed object.

The porous member 100 according to this embodiment has a porous body with multiple pores. The pores have multiple openings and constitute the porous portion of the porous member 100. The size of the pores is not particularly limited, but the pores may be micropores with a pore diameter of less than 2 nm, mesopores with a pore diameter in the range of 2 to 50 nm, or macropores with a pore diameter of more than 50 nm. However, depending on the size of the molecules contained in the ink, penetration through micropores and mesopores may be difficult. Therefore, it is preferable that the pores be macropores.

The material of the porous body is not particularly limited, but may be, for example, an inorganic or organic material. It is preferable that the porous body be elastic and flexible. This prevents the porous body from damaging the object to be printed during printing. Furthermore, if the surface of the object to be printed has a three-dimensional shape, such as a curved surface, a flexible porous body will deform to conform to the surface of the object, making it easier to align the openings with the object, making printing easier. Highly flexible materials include porous bodies made of various organic polymer materials, such as polyolefin-based or polyurethane-based polymer materials.

The porous body may be made of a fibrous material such as cloth or nonwoven fabric, or may be a sponge made of carbohydrates such as cellulose. When the porous body is made of a fibrous material, the gaps between the fibers form pores. The size of the air bubbles contained in the sponge may be, for example, an average diameter of 1500 to 3000 μm.

When an organic solvent is used as the solvent, it is preferable that the porous body be difficult to dissolve in the organic solvent. For example, it is preferable that the porous body be made of a polyolefin-based polymer material. Felt and sheets whose fibers are made of fluorine-based organic molecules also have excellent solvent resistance and can be used effectively as porous bodies.

The porous member 100 according to this embodiment has a molecular modification film formed to cover the inner surface of the pores. The molecular modification film according to this embodiment is formed to cover the inner surface of the pores of the porous body, and may be, for example, an organic thin film such as a self-assembled monolayer (SAM). Forming a molecular modification film such as a SAM film in the pores makes it easier for ink to adhere to the printing target and suppresses dissolution of the porous body into the ink.

The supply member 140 is configured to supply ink to the pores of the porous member 100 as needed. For example, the supply member 140 and the adhesive layer 120 may have holes or meshes that communicate with the pores, and ink may be supplied from the supply member 140 to the pores through these holes or meshes. The supply member 140 may also be configured to supply ink to the pores as the ink filled in the pores decreases due to printing.

In this embodiment, an example is described in which ink is supplied using a supply member 140 adhered to the porous member 100 by an adhesive layer 120, but the method of supplying ink to the porous member 100 is not limited to this. For example, ink may be supplied to the porous member using a dispenser such as a syringe. In this case, it is also possible to directly insert a syringe needle into the porous member 100, integrate the porous member 100 and the dispenser, and use the dispenser to supply ink to the porous member while printing. In this case, the dispenser may be fixed directly to the porous member 100 without an adhesive layer or the like.

[Printing method]
2 is a flowchart illustrating the flow of a printing method according to one embodiment of the present invention. As shown in FIG. 2, the printing method according to this embodiment includes a member preparation step (S1), a target object preparation step (S2), and an attachment step (S3). Note that the steps in the printing method do not have to be performed in the order shown in FIG. 2. For example, the target object preparation step may be performed before the member preparation step, or the target object preparation step and the member preparation step may be performed in parallel.

The component preparation process is a process of preparing a porous component whose pores are filled with ink. For example, in the component preparation process, a porous component whose pores are filled with ink may be prepared by filling the pores of the porous component with ink. It is desirable that the amount of ink filled is sufficient to roughly reach saturation. In addition, various filling methods may be used, such as dipping the porous component into an ink container or dispensing.

In the component preparation process, various surface treatments may be performed on the pores before filling them with ink. For example, the component preparation process may include a film formation process in which a molecularly modified film is formed to cover the inner surfaces of the pores. Examples of processes for forming a molecularly modified film include silane coupling treatment, which can be performed using a silane coupling agent such as alkoxysilane, chlorosilane, or alkylchlorosilane. These silane coupling agents may contain amino groups and epoxy groups. Silane coupling treatments include liquid-phase treatments and gas-phase treatments. Gas-phase treatments are preferred because they can be used to treat large areas and large volumes with a small amount of silane coupling agent, and are therefore highly productive and versatile. By performing such surface treatments on a porous material, a porous component can be prepared with a molecularly modified film formed to cover the inner surfaces of the pores.

FIG. 3 is a diagram illustrating an example of a film formation process according to this embodiment. As shown in FIG. 3 , in the film formation process according to this embodiment, a porous body 110 and a liquid film material 24 are placed inside a container 20, and the container 20 is sealed with a lid 22. The porous body may be pretreated using a UV (ultraviolet) ozone cleaner to shield the porous body from direct UV light irradiation and oxidize the porous surface and interior with ozone generated within the cleaner, thereby making the porous body more susceptible to reaction with a silane coupling agent. Here, an example is described in which the porous body 110 is made of a polyolefin-based organic material, and the film material 24 is FAS (1H,1H,2H,2H-Perfluorodecyltriethoxysilane), a fluorine-based material represented by the following chemical formula:

By heating the film material 24, for example, at 65-120°C, and adhering the gasified film material 24 to the interior of the pores of the porous body 110, a molecularly modified film can be formed to cover the inner surfaces of the pores. After the treatment, the porous body 110 may still have unreacted silane coupling agent residue on its surface. Therefore, the treated porous body 110 may be cleaned by immersing it in IPA (isopropyl alcohol) for, for example, 20 minutes, and then dried in a vacuum oven. Forming a molecularly modified film on the inner surfaces of the pores in this manner improves the water repellency of the pores. The film formation process of this embodiment uses a gas-phase treatment, which allows molecules to penetrate deep into the pores of the porous body 110, more reliably molecularly modifying the pore surfaces.

An example of the results of a water-repellent treatment will be described with reference to Figure 4. Figure 4 shows a component 112 for which water repellency is to be measured and a water droplet 26 dropped on its surface. The inventors confirmed that by performing a surface treatment using FAS (heating temperature: 65°C, heating time: 24 hours) on a polyolefin-based organic material to form a molecularly modified film, the water contact angle θ increased from 110° to 130°, improving the water repellency of the organic material. Furthermore, when observing the change in the contact angle over time, it was confirmed that without molecular modification, the water contact angle changed from 110° to 108° five minutes after the water droplet 26 was dropped. On the other hand, with molecular modification, it was confirmed that the water contact angle remained at 130° five minutes after the water droplet 26 was dropped. This change in the contact angle over time indicates the ease with which the pores of the porous component absorb liquid, indicating that the material was molecularly modified with FAS.

The film material 24 is not limited to FAS, but may be, for example, APTES ((3-Aminopropyl)triethoxysilane) represented by the following chemical formula:

In this case, the porous body 110 and membrane material 24 are arranged as shown in Figure 3, and the membrane material 24 is heated, for example, at 65°C for 24 hours. The gasified membrane material 24 adheres to the inside of the pores of the porous body 110, forming a molecularly modified membrane that covers the inner surface of the pores. The inventors have confirmed that when such a surface treatment is performed, the contact angle (with water) becomes 125°, improving water repellency. The cleaning and drying methods after treatment are the same as when using FAS described above.

The object preparation process is a process of preparing a printing object having a pattern area formed on its surface. In the object preparation process, the printing object may be prepared by forming a pattern area having a desired shape on the surface of the substrate of the printing object. The pattern area in this embodiment is configured to be more likely to adhere to or retain ink than other areas on the surface of the printing object.

Specifically, in the object preparation process, a pattern region having a different surface free energy than other regions may be formed on the surface of the substrate of the printing object. For example, a substrate whose surface is made of a polymer material may be prepared, the surface of the substrate may be covered with a mask having the desired pattern, and ultraviolet light may be irradiated onto the surface of the substrate through the mask. The ultraviolet light may be, for example, vacuum ultraviolet light with a wavelength of 200 nm or less (ultraviolet light with a wavelength of 172 to 250 nm), specifically, 172 nm vacuum ultraviolet light generated by a xenon excimer. Irradiating the substrate with ultraviolet light modifies the surface of the substrate to allow metal nanoparticles to be fused, forming a pattern region. In addition to the ultraviolet light treatment method described above, various plasma treatments are also possible.

In addition, in the object preparation process, a pattern area may be realized by forming a hydrophilic surface and a hydrophobic surface on the surface of the printing object. In this case, the pattern area may be composed of a hydrophilic surface. By adjusting the surface wettability between hydrophilic and hydrophobic in this manner, printing using aqueous ink becomes possible, and aqueous ink can be adhered to and retained in the pattern area.

Pattern regions are not limited to those formed by varying the surface free energy from the surrounding area; they may be formed by providing areas with different three-dimensional structures, such as steps and grooves (banks). Alternatively, pattern regions may be formed as areas with different surface free energy and three-dimensional structures from the surrounding area. Areas with different three-dimensional structures can be formed using, for example, photolithography, and various methods, such as etching using light and chemicals, are also possible. Another method for forming pattern regions is heat pressing using a mold. These grooves are configured to hold ink more easily than other areas, and the pattern is formed by utilizing capillary action, which causes the liquid to spread along the steps and grooves. The depth of these grooves may be, for example, 10 nm to 10 μm.

The surface of the printing object on which the pattern area is formed may have various shapes, such as a flat surface, a curved surface, or other three-dimensional or free-form shapes. In this embodiment, an example is described in which the surface of the printing object on which the pattern area is formed is composed of a curved surface.

An example of the configuration of a printing object according to this embodiment will be described with reference to Figures 5(a) and (b). Figure 5(a) is a side view of a printing object 30 according to one embodiment of the present invention, and Figure 5(b) is a top view of a printing object 30 according to one embodiment of the present invention.

As shown in Figures 5(a) and (b), the printing object 30 according to this embodiment has a flat portion 300 and a curved portion 302. As shown in Figure 5(b), a pattern area 304 (area with dotted hatching) is formed in the curved portion 302. Note that the shape of the pattern area 304 is not limited to the rectangular shape shown in Figure 5(b), and may include various shapes such as linear, circular, elliptical, or polygonal.

Figures 6(a) and (b) are diagrams for explaining the adhesion process according to this embodiment. Figure 6(a) is a diagram showing the state when starting to sweep the printing member 10, and Figure 6(b) is a diagram showing the state after sweeping the printing member 10.

The adhesion process is a process in which the porous member 100 is swept over the surface of the printing object 30, thereby adhering the ink filled in the pores of the porous member 100 to the pattern area. In the adhesion process of this embodiment, the opening surface 102 of the porous member 100 of the printing member 10 is pressed against the surface of the curved portion 302 of the printing object 30, and the printing member 10 is swept along that surface. This causes the ink filled in the pores of the porous member 100 to adhere to the pattern area on the surface of the curved portion 302.

At this time, ink can be applied to the pattern area by utilizing the balance between the capillary phenomenon (moisture absorption) created by the pores of the porous member 100 and the capillary phenomenon (coating liquid, coating) between the porous member 100 and the surface (curved surface portion 302) of the printing object 30. According to the printing method of this embodiment, by utilizing (or adjusting) the balance between the magnitudes of the two capillary phenomena, it is possible to more easily create the desired printing pattern. Naturally, areas where a printing pattern is not required must have a surface state that repels ink.

The sweep speed of the printing member 10 is not particularly limited, but may be adjusted depending on the surface tension of the ink, the drying speed of the solvent contained in the ink, and the resolution of the printed pattern. If the sweep speed is too fast, adjacent patterns will not separate, resulting in poor printing; if the sweep speed is too slow, solid matter may precipitate, causing defects such as scratches on the printed object. For example, the sweep speed may be 0.1 to 500 mm/sec, with 1 mm/sec or higher being preferable, and 5 mm/sec or higher being even more practical.

It is preferable to sweep the printing member 10 while pressing it against the surface of the printing object 30. For example, sweeping may be performed while pressing the printing member 10 against the printing object 30 with a load approximately equal to the printing member 10's own weight. In this embodiment, the ink filling state in the pores of the porous member 100 is saturated (or close to saturated). Therefore, during sweeping, a small amount of ink has seeped out onto the surface of the porous member 100. Therefore, when the printing member 10 is pressed against the printing object 30, ink is always present between the porous member 100 and the printing object 30, and the porous member 100 (more specifically, the opening surface 102) is not in direct contact with the printing object 30.

The deposition process according to this embodiment can form a pattern with a thickness of approximately 10 to 2000 nm on the surface of the printing object. If a greater thickness is required, the printing pattern can be made thicker by repeating the deposition process, such as by applying multiple coats.

Figure 7 is a top view of an example of a printing object 32 after printing using the printing method of this embodiment. As shown in Figure 7, ink is applied to area 306 (area with diagonal hatching) corresponding to pattern area 304 in Figure 5 (b), and a printing pattern is printed on the printing object 32.

As described above, the printing method according to this embodiment makes it possible to print print patterns on curved surfaces and to uniformly apply ink to three-dimensional or free-form shapes, achieving high-precision printing. Furthermore, by using the printing method according to this embodiment to form various wiring patterns, for example, a method for manufacturing electronic devices can be provided. Therefore, the printing method according to this embodiment makes it possible to manufacture electronic devices with complex shapes (such as curved free-form shapes) that cannot be realized using current processes. Furthermore, the printing method according to this embodiment can be used with inks containing various materials, not just metals, such as organic semiconductors, providing a highly versatile method for manufacturing electronic devices.

The electronic device manufacturing method according to this embodiment can be used as a manufacturing method for a variety of products, such as products used in the automotive, medical, IoT (Internet of Things) and robotics fields. Specifically, the electronic device manufacturing method according to one embodiment of the present invention can be applied to a wide range of applications, including various display elements, sensors and electronic circuits. The printing method according to this embodiment can be a highly useful industrial technique as a printing technology for objects with three-dimensional structures.

Conventional techniques for printing wiring on curved surfaces include the methods described in the following references.
(References)
[1] Y. Yoshida, H. Wada, K. Izumi, and S. Tokito, “Highly conductive metal interconnects on three dimensional objects fabricated with omnidirectional ink jet printing technology”, JJAP. 56, 05EA01 (2017).
[2] K. Izumi, Y. Yoshida, and S. Tokito, “Novel soft blanket gravure printing technology with an improved ink transfer process”, Flex. Print. Electron. 2, 024003 (2017).
[3] K. Izumi, Y. Yoshida, and S. Tokito, “Soft blanket gravure printing technology for finely patterned conductive layers on three-dimensional or curved surfaces”, JJAP. 56, 05EA03 (2017).
[4] K. Nomura, Y. Kusaka, H. Ushijima, K. Nagase, and H. Ikedo, “Screen-pad printing for electrode patterning on curvy surfaces”, Microsyst Technol. 22, 635-638 (2016).

Conventional printing technologies are limited to limited shapes and the precision of printed objects (such as wiring) is poor, with no ability to form wiring with a line width of 30 μm or less. Furthermore, photolithography has few applications to curved surfaces, and is unable to adapt to objects with steps of, for example, 1.5 cm or more in height, as it is unable to follow the height. The printing method of this embodiment enables high-resolution printing with a line width of 10 μm or less, making it advantageous not only for free-form device creation, but also for miniaturizing devices.

The printing method according to this embodiment also leads to the creation of new applications, making it possible to not only turn the fingertips of robotic hands into sensors, but also to manufacture sensors that completely surround the fingertips. For example, by combining these sensors with myoelectric elements, new prosthetic limbs and robotic hands can be proposed as service robots using AI (Artificial Intelligence). In recent years, attempts have been made to directly bond prosthetic limbs to curved bones, and the printing method according to this embodiment could be useful. Furthermore, because it is possible to construct not only electrode layers but also organic semiconductor layers, the printing method according to this embodiment can be applied to a variety of electronic circuit manufacturing technologies.

In addition, the printing method according to this embodiment allows the entire process to be carried out at a relatively low temperature. For example, with the printing method according to this embodiment, the entire process can be carried out at a temperature of 100°C or less, and by carefully selecting the components, the entire process can be carried out at a temperature of 60°C or less.

[Example]
The present invention will be explained in more detail below using examples, but the following descriptions of printing members, printing objects, inks, etc. do not limit the embodiments of the present invention in any way.

Example 1
In Example 1, a substrate made of a polycarbonate (PC) film was prepared, on the surface of which Cytop (registered trademark) was formed, with a curved portion at the center, like the printing object 30 described with reference to Figure 5. The printing object was prepared by irradiating the surface of the substrate with ultraviolet light having a wavelength of 172 nm through a mask to form a pattern area.

In Example 1, porous bodies made of a polyolefin-based organic material (MAPS, manufactured by Inoac Corporation) were prepared. Here, porous body A (thickness: 2.25 mm, cell diameter: 50 μm, porosity: 85%, density: 0.139 g/cm ³ , tensile strength: 229 KPa, elongation: 220%, hardness: 8 (Asker C)), porous body B (thickness: 1.85 mm, cell diameter: 90 μm, porosity: 80%, density: 0.170 g/cm ³ , tensile strength: 450 KPa, elongation: 170%, hardness: 11 (Asker C)), and porous body C (thickness: 1.50 mm, cell diameter: 200 μm, porosity: 80%, density: 0.2 g/cm ³ , tensile strength: 670 KPa, elongation: 150%, hardness: 35 (Asker C)) were prepared. When the flexibility of these porous bodies was checked, the order of softness was porous bodies A, B, and C. When the moisture absorption was checked, the order of moisture absorption was highest, followed by porous bodies A, B, and C. In Example 1, of these porous bodies, porous body A was used.

This porous body was surface-treated using FAS (heating temperature: 65°C, heating time: 24 hours), forming a molecular modification film in the pores of the porous body to obtain a porous member. This porous member was then impregnated with an ink consisting of silver nanoparticles dispersed in an organic solvent (a mixed solvent of octane, butanol, and methanol). The porous member was then bonded to a supply member to form a printing member. Next, printing was performed by pressing the open surface of the porous member against the surface of the printing object and sweeping the printing member to deposit the ink in the pattern area of the printing object. Additional ink was impregnated into the porous member as needed during printing. Note that to achieve good printing, printing must be performed when the ink filling level in the porous member is saturated or close to saturated; therefore, a dispenser or similar device is useful for supplying ink.

Figure 8 shows the printing result of electrode wiring in Example 1. As shown in Figure 8, the printing object 34 in Example 1 has a flat portion 340 and a curved portion 342, and electrode wiring is printed on the surface of the curved portion 342. In this way, it was confirmed that the printing method in one embodiment of the present invention makes it possible to print electrode wiring on a curved surface.

Example 2
In Example 2, a substrate made of a polycarbonate film with a curved Cytop formed on its surface was prepared, similar to Example 1. The surface of the substrate was irradiated with ultraviolet light having a wavelength of 172 nm through a mask to form multiple 1 mm square pattern areas, thereby preparing a printing object.

In Example 2, the organic semiconductor P3HT (poly(3-hexylthiophene-2,5-diyl)) was dissolved in o-xylene to prepare an ink with a concentration of 0.6 wt %. In Example 2, a porous member was prepared in the same manner as in Example 1, except that the porous body was not surface-treated. A printing member was prepared by filling the porous member with the prepared ink. An array of printing patterns was formed by sweeping this printing member over the surface of the object to be printed.

In Example 2, the porous body was not subjected to a surface treatment such as SAMs, and there was concern that o-xylene might dissolve the polyolefin-based organic material that constitutes the porous body. However, when this example was carried out, no particular abnormalities were observed in the porous body. However, if the porous body is to be used repeatedly, it is considered preferable to apply a surface treatment such as SAMs.

Figure 9 shows a photograph of the surface 350 of the printing object after printing in Example 2, observed with an optical microscope. As shown in Figure 9, it can be seen that an array of 1 mm square printing patterns 352 has been formed on the surface 350 of the printing object.

Example 3
In Example 3, a printing object and a printing member were prepared in the same manner as in Example 2, except for the ink. In Example 3, a flexible ferroelectric substance ([MDABCO][PF6]) described in the following reference was dissolved in a mixed solvent of water and isopropyl alcohol to prepare an ink with a concentration of 5 wt %. A printing member was prepared by filling a porous body with this ink, and printing was performed using this printing member.

(References)
[5] J. Harada, M. Takehisa, Y. Kawamura, H. Takahashi, and Y. Takahashi, “Plastic/Ferroelectric Crystals with Distorted Molecular Arrangement: Ferroelectricity in Bulk Polycrystalline Films through Lattice Reorientation”, Adv. Electron. Mater. 8, 2101415 (2022).

Figure 10 is a photograph showing the appearance of the printing object 354 after printing in Example 3. As shown in Figure 10, an array of 1 mm square printing patterns 358 can be formed on the curved surface 356 of the printing object 354. Furthermore, according to this example, the ink can be prepared using a solvent containing water and alcohol, and the compounds that serve as the ink solute do not contain rare metals, making it possible to print under conditions that place a low burden on the environment.

Example 4
In Example 4, a flat substrate was prepared by attaching a PC film to a glass plate and forming a Cytop film on the PC film. The surface of this flat substrate was irradiated with 172 nm deep ultraviolet light through a mask to form a linear pattern area, preparing a printing object. Next, a printing member was prepared in the same manner as in Example 1, and wiring was printed on the printing object by sweeping the printing member while pressing the open surface of the porous member of the printing member against the surface of the printing object.

Figure 11 shows the results of wiring printing in Example 4. As shown in Figure 11, wiring 362, 364, 366, 368, 370, and 372 with line widths of 1 μm to 50 μm were printed on the surface of the printing object 360. As shown in Figure 11, in Example 4, fine wiring was achieved with high precision.

When the resistivity of these wirings was measured, the resistivity of the wiring with a line width of 7.5 μm was 4.09×10 ⁻⁵ Ω·cm, the resistivity of the wiring with a line width of 10 μm was 3.62×10 ⁻⁵ Ω·cm, the resistivity of the wiring with a line width of 20 μm was 1.95×10 ⁻⁵ Ω·cm, and the resistivity of the wiring with a line width of 50 μm was 1.00×10 ⁻⁵ Ω·cm. Thus, in Example 4, wirings with good electrical conductivity were realized even when the line width was 10 μm or less. The thickness of these wirings was all 50 nm.

Example 5
In Example 5, a flat substrate was prepared by attaching a PC film to a glass plate and forming a Cytop film on the PC film. The substrate was then irradiated with 172 nm deep ultraviolet light through a mask to form multiple rectangular pattern areas. A printing member was then prepared in the same manner as in Example 1, except that the ink was changed to an ink containing P3HT. The printing member was then swept to print multiple rectangular organic semiconductors (organic semiconductor arrays).

Figure 12 shows the printing results of an organic semiconductor array according to Example 5. As shown in Figure 12, in Example 5, multiple rectangular printing patterns were formed on the surface of the printing object 380. As shown in Figure 12, a high-resolution printing pattern was formed, which is equivalent to a resolution of a 200-300 ppi TFT (Thin Film Transistor) array. In the printing pattern shown in Figure 12, the horizontal length was 21.4-21.9 μm, and the vertical length was 34.0-35.2 μm.

Example 6
In Example 6, an epoxy resin-based photoresist (SU-8 3000, manufactured by Nippon Kayaku Co., Ltd.) was used as the substrate for the printing object. First, a film was formed by spin coating under the conditions of Slope/2 seconds → 500 rpm/5 seconds → 3000 rpm/60 seconds, and the film was heated at 95°C/2 minutes using a hot plate. The film was then irradiated with ultraviolet light of 365 nm wavelength and an intensity of 200 mJ/ ^cm² . This formed grooves with a width of approximately 30 μm in the film.

Next, the film was baked at 65°C for 1 minute and then 95°C for 2 minutes during the post-exposure bake (PEB) process. Two PGEMA (propylene glycol monomethyl ether acetate PEGEMIA) baths were prepared. The film was immersed in the first bath for 30 seconds and then in the second bath for another 30 seconds, for a total of 1 minute. The film was then immersed in an IPA (isopropyl alcohol) bath for 1 minute, rinsed with IPA, and spin-dried at 2000 rpm for 40 seconds. The film was then hard-baked at 150°C for 30 minutes to dry. Because the film is a highly wettable material, a water-repellent treatment was applied to adjust its wettability. This improved the water droplet contact angle from 75° to 101°. The water-repellent treated film was used as the printing target.

Figure 13(a) is a diagram showing the surface of a printing object 400 on which a pattern area according to Example 6 has been formed. As shown in Figure 13(a), a printing object 400 was produced in which a rectangular groove 402 measuring 25 μm in length in the vertical direction, 40 μm in length in the horizontal direction, and 6 μm in depth was formed on the surface. Next, a printing member prepared in the same manner as in Example 1 was swept over the surface of the printing object 400, and printing was performed.

Figure 13(b) is a diagram showing the surface of the printing object 400 after printing in Example 6. As shown in Figure 13(b), it was confirmed that ink has entered many of the grooves 412 formed on the surface, and printing has been successful. In this way, it was confirmed that by using the printing method according to one embodiment of the present invention, printing is possible by allowing ink to enter the grooves formed on the surface of the printing object, without forming regions with different surface free energies.

Example 7
In Example 7, a printing object was prepared in the same manner as in Example 6, except that the grooves were linear with a depth of 6 μm and a width of 60 μm, and printing was performed on the surface.

Figure 14 shows the printing results for Example 7. As shown in Figure 14, grooves 422 are formed on the surface of the printing object 420, and it can be seen that ink 424 has penetrated into some of them.

(Example 8)
In Example 8, a printing object was prepared using polydimethylsiloxane (PDMS) (SIM260, manufactured by Shin-Etsu Chemical Co., Ltd.) instead of the photoresist (SU-8) used in Examples 6 and 7. Specifically, a mold having a 6 μm-high convex pattern was subjected to a release treatment, and an elastomer mixture of PDMS and a curing agent was poured into the mold. The mixture was baked at 150°C for 30 minutes to harden the silicone elastomer, which was then peeled off from the mold. This resulted in a molded image of the mold, yielding a flat printing object made of PDMS with grooves (concave patterns).

In Example 8, a printing member was prepared in the same manner as in Example 1, except for the ink. In Example 8, the above-mentioned [MDABCO][PF6] was dissolved in a mixed solvent of aromatic solvent, alcohol, and water to prepare an ink with a concentration of 2.5 wt %. This ink was filled into a porous body to prepare a printing member, and printing was performed.

Figure 15 shows a photograph of the surface 440 of the printing object after printing in Example 8, observed with an optical microscope. As shown in Figure 15, it can be seen that ink 442 is contained in the grooves formed on the surface 440. Although there are also grooves 444 that do not contain ink, it is believed that printing accuracy can be improved by optimizing conditions such as the coating speed, surface tension of the ink, height difference of the grooves, and implementation environment.

[supplement]
The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and treatment processes, and that such modifications are also within the scope of the present invention.

The present invention can be used in printing methods, manufacturing methods for electronic devices, and porous members.

10 Printing member, 30, 32, 34 Printing object, 50 Line width, 100 Porous member, 102 Open surface, 110 Porous body, 120 Adhesive layer, 140 Supply member, 300, 340 Flat portion, 302, 342, 356 Curved portion, 304 Pattern area, 352, 358 Printing pattern, 360, 354, 380, 400 Printing object, 362, 364, 366, 368, 370, 372 Wiring, 424, 442 Ink, 402, 412, 422, 444 Groove

Claims (8)

a member preparation step of preparing a porous member having holes filled with ink;
an object preparation step of preparing a printing object having a pattern area formed on its surface;
an application step of applying the ink filled in the pore portions to the pattern area by sweeping the pore member over the surface of the printing object,
The member preparation step includes a film formation step of forming a molecular modification film on the inner surface of the pore portion of the porous member.
Printing method. The porous member has a porous body,
The film forming step includes a vapor phase treatment for forming a molecular modified film on the inner surfaces of the pores of the porous body.
The printing method according to claim 1 . the ink contains metal nanoparticles;
The pattern region includes a surface-modified region that is formed by irradiating a polymer material with ultraviolet light and that fuses with the metal nanoparticles.
The printing method according to claim 1 or 2 . the ink comprises a conductive material, an organic semiconductor, or a ferroelectric material;
The printing method according to claim 1 or 2 . The pore diameter of the pores is 50 nm to 3 mm.
The printing method according to claim 1 or 2 . The pattern area is composed of grooves.
The printing method according to claim 1 or 2 . The surface of the printing object is composed of a curved surface.
The printing method according to claim 1 or 2 . A method for manufacturing an electronic device using the printing method according to claim 1 or 2 .