KR101067276B1 - Method for Forming Micro-Pattern by Near-Field Electro-Spinning Technique - Google Patents

Abstract

The present invention relates to a method for forming a micropattern using a direct printing method of a near field electrospinning method. The method for forming a micropattern according to the present invention comprises the steps of preparing an electrospinning solution by mixing a material for producing a pattern in an organic solvent; Discharging the electrospinning solution from the spray nozzle with a voltage applied thereto; And attaching the electrospinning solution discharged from the spray nozzle to the surface of the substrate positioned on the collector having the grounding property to form a fine pattern, wherein the spray nozzle is designed in the form of a tapered tip to have a line width of 20 μm or less. A fine pattern is formed.

Electrospinning, Near Field, Direct Impression, Printed Circuit Board, Photoresist

Description

Method for Forming Micropattern by Direct Printing Method of Near Field Electrospinning Method {Method for Forming Micro-Pattern by Near-Field Electro-Spinning Technique}

The present invention relates to a method for forming a fine pattern using a direct printing method of near field electrospinning. More specifically, the present invention relates to a method of forming a fine pattern through a close-up electrospinning method by manufacturing a conductive material, photoresist and / or insulating materials in an electrospinning solution.

In general, a printed circuit board expresses electrical wiring connecting circuit components in a wiring diagram based on a circuit design, and completes it as a wiring diagram on a substrate by techniques such as pattern printing and etching. Is as follows. After attaching a thin film of copper to a thin substrate made of epoxy or bakelite resin as an insulator, a resist is printed on the circuit wiring which is desired to remain as a copper film. When the printed substrate is immersed in an etching solution that can dissolve copper, the portion free of resist is melted, and then the resist is removed, leaving only the copper thin film in a desired pattern.

The conventional printed circuit board mainly uses a screen printing method, which is manufactured by performing an exposure and development process through a separate process of manufacturing a screen, that is, a plate making process of adhering the screen to a frame. Therefore, a large amount of facility investment is required to produce the screen, and a lot of manpower and time are also wasted. Also, the printing of the screen lacks the accuracy of the printed image, making it difficult to print fine images.

That is, as the screen is adhered to the substrate and the printing is performed, local deformation and damage of the printed image occurs due to the pressure of the squeegee of the screen. Considering the recent tendency of miniaturization of printed circuit boards, Deformation and damage lead to fatal defects. In particular, in the case of a double-sided printed circuit board, it is necessary to control the exact position of the front and back of the printed image, that is, the printed image on both sides. The printing using the screen matches the printing on both sides because the screen is printed after printing on one side. It takes a lot of trouble to get it done.

In the case of printing using a screen, the thickness of the printed image is thick, and thus, the process of curing the ink requires high brightness and a lot of time. In order to solve this problem, it is possible to use the thin film manufacturing process used in the existing semiconductor process, but this technology also can be used for photo-mask fabrication, photoresist and organic / inorganic composite coating, exposure, development and etching. There is a problem of going through the process and using expensive equipment.

In addition, since the semiconductor thin film manufacturing process basically uses an etching liquid which is a highly oxidizing chemical, there is a fundamental environmental problem that the process is very harmful to human body and nature.

As described above, the pattern has recently been used as an alternative to the conventional circuit pattern fabrication method which has problems such as generation of human hazardous substances and industrial wastes due to chemical etching, formation of limited precision printing patterns, and low productivity due to the complexity of the process. Direct writing technology, which produces a pattern by directly printing a surface of a substrate to be manufactured, has attracted attention.

Direct patterning technology produces the pattern by direct printing method instead of the complicated manufacturing method that used expensive vacuum process and photolithography process in forming the pattern for manufacturing electronic parts. This is a technology that can overcome economic and technical limitations. In FIG. 1, a micropattern manufacturing process using a direct printing method and a pattern manufacturing process using a conventional photolithography method are compared. As shown in FIG. 1, the direct printing technique is a technique of selectively applying a required material only to a necessary part on a substrate to form a pattern. After raising a necessary material on the entire substrate, a photosensitive agent is applied, a partial exposure through a photomask, development, and etching. In addition, the complex process of removing the photoresist can radically simplify the four steps or the process steps compared to the conventional method of producing patterns.

Direct printing technology enables innovative patterns to be processed at atmospheric pressure with simplified process steps, resulting in very low cost compared to traditional patterning technologies that require expensive vacuum equipment. Because of the coating method, the material cost reduction effect is also very large compared to the existing patterning technology that generates a large amount of material waste. In addition, because it is a very simple way to form a pattern by selectively applying the required material on the substrate, unlike the conventional patterning technology that has a variety of constraints on the choice of applied substrate and material by complex process steps, glass, Various substrates such as a polymer film and paper may be considered, and application of various materials such as an organic material and an inorganic material may be considered in terms of materials.

Direct printing technology is a technology that can secure market competitiveness through the dramatic reduction in manufacturing costs in the manufacturing of electrical / electronic devices including nanoelectronic components, as shown in Figure 2 disposer that can be processed immediately after use It is a key core technology that can be applied to various new industries such as flexible electronics and flexible electronics, which can be used to secure the leading market dominance in new industries. have. In addition, the present invention can be applied as a repair technology for improving the yield of devices in existing industrial fields including the semiconductor and display fields, which are country-based industries.

Among the direct printing methods, the inkjet method is most commonly used for manufacturing printed circuit boards. However, the inkjet technology has a limitation in that it is difficult to form a thick film having a thickness of several μm or more, and a high resolution pattern having a line width of 50 μm or less is difficult. The low viscosity causes the ink droplets to spread and fail to maintain their shape after contact with the substrate, resulting in a thinner pattern and a wider pattern.

Attempts have been made to improve this spreading through surface modification of the substrate, but the inkjet-produced line width is still very wide, about 50 μm, which is not a fundamental solution. When the size of physically sprayed droplets is 20 µm or less, surface energy is dominated because the kinetic energy added to the ink droplets in the direction of the substrate is insufficient, and the impact group is not properly formed. The width of the pattern is 1.5 times the diameter of the ink droplets. Considering that it is generally formed to be about 2 times, there is a fundamental problem in forming a pattern having a resolution of 20 μm or less by the inkjet method.

The fabrication of highly integrated printed circuit boards using direct printing requires patterning techniques ranging from tens of micrometers to hundreds of nanometers in resolution, and there are no commercially available techniques for patterning in this area. Therefore, in order to improve the performance and high value of a device that is implemented by a direct printing method, a technology for implementing an active device by a direct printing method is required, and a resolution of 20 μm or less is required for the direct printing of an active device. Since there is no corresponding technology, the development of technology for this part is urgently required.

In addition, in the pattern made of the conventional conductive ink composed of metal nanoparticles, a binder and a solvent, the movement of the electrons inside the pattern is prevented by the binder as an insulator, so that the electrical resistance is 4 to 5 times higher than that of the metal itself. There is a basic problem that is increased over. This is one of the biggest obstacles in producing highly integrated and high performance circuits for processing large amounts of information in a short time.

In the modern industry, the realization of products that are smaller, thinner and lighter while maximizing their function is the most important task of the high-tech electronic industry. For example, as devices such as memory and CPUs of electronic products are becoming smaller and more integrated, various electronic chips that are materials for these devices and printed circuit boards for mounting the chips have become smaller and thinner in recent years. ought. Therefore, printed circuit boards and electronic chips for future multi-functional high-speed information devices require much smaller line widths than now. Modern device devices that output data faster and more require much higher interconnect density, and in order to meet this, a minimum line width smaller than 50 μm, which is the line width limit of current inkjet printing method, can be achieved. Technology development is urgently needed.

In addition, 1) conductive material such as mercury nanoparticles, 2) semiconductor circuit patterning material such as AZ-5214 and Sipley-1200, and 3) insulating nano like Al ₂ O ₃ Development of micropattern fabrication technology using insulating materials composed of particles and polymer materials such as PSS, PPE, P3HT, PEDOT, and collagen should also be developed.

Accordingly, an object of the present invention is to provide a method of forming a fine pattern by a direct printing method by a near field electrospinning method capable of producing a fine pattern having a line width of 20 μm or less.

In order to solve the above problems, the present invention

Preparing an electrospinning solution by mixing a pattern preparation material in an organic solvent;

Discharging the electrospinning solution from the spray nozzle with a voltage applied thereto; And

A method of forming a micropattern using a near field electrospinning method comprising attaching an electrospinning solution discharged from a spray nozzle to a surface of a substrate positioned on a collector having a grounding property to form a micropattern.

In the method of forming a fine pattern according to the present invention, the spray nozzle is designed in the form of a taper tip, the nozzle width of which is narrowed toward the end, so that the droplet size of the solution formed at the nozzle tip is 100 μm or less, and the tapered tip structure It is preferable that the spray nozzle of is a nozzle team machining angle between 20 and 45 degrees, the distance between the nozzle and the collector is 3 mm or less, and the material of the nozzle is Teflon, plastic or stainless steel.

In the method for forming a micropattern according to the present invention, the organic solvent for preparing the electrospinning solution is preferably isopropyl alcohol, DMF, THF or water, and PVA (polyvinyl acetate), PEO ( It is preferable to further contain an organic compound such as polyethylene oxide) or PVP (poly-4-vinylphenol).

In the method for forming a micropattern according to the present invention, the material for producing a pattern includes a conductive material, an organic-inorganic composite, a photoresist or an insulating material, and the conductive material is P3HT (poly-3-hexylthiophene), PEDOT ( A polymer selected from the group consisting of poly (3,4-ethylenedioxythiophene)), PSS (poly (styrenesulfonate)) and PPE (polyphenylene ether), or nanoparticles selected from the group consisting of silver, copper and gold The photoresist is preferably a HOECHST series photoresist such as AZ-5214 sold by Hoechst, or a Shipley series photoresist such as S-1400 sold by Shipley, and Al ₂ O ₃ as an insulating material. Is preferably a ceramic or diamond selected from the group consisting of SiO ₂ and c-BN (boron-nitride).

In the method for forming a micropattern according to the present invention, in order to form a micropattern having a line width of 20 μm or less, the spray nozzle has a tapered-tip structure and is designed such that the nozzle radius inside is 20 μm to 50 μm, and Adjust the distance between the nozzle and the collector of the spinning device at a distance of 500 μm to 3 mm, adjust the voltage applied to the nozzle to 3 to 15 kV, and move the nozzle in the XYZ direction at 5 to 15 cm / sec. It is desirable to adjust.

In the method for forming a micropattern according to the present invention, after the formation of the micropattern, the method may further include removing an organic solvent and residual organic components by heat treatment, plasma treatment, or UV O ₃ treatment.

The present invention has the following effects.

First, by designing the tip of the nozzle in a tapered shape, not only can the size of the droplets formed at the end of the nozzle be smaller than before, but also no droplets are generated. The fine pattern which is 20 micrometers or less can be produced. Through this, it is possible to manufacture a high-precision printed circuit board with improved mounting density of the pattern.

Second, it is possible to develop a fine pattern manufacturing technology for various materials constituting the printed circuit board by the direct printing method at the same time the pattern line width is reduced.

Third, compared to the conventional semiconductor patterning process, it is possible to produce a fine pattern by a simple direct printing method, thereby saving the overall process time and process cost required for manufacturing a printed circuit board.

Fourth, through the introduction of the near-field electrospinning method, it is possible to overcome the difficulty of controlling the clogging and fine line width of the nozzle of the inkjet method, which is a conventional direct printing method.

Sixth, the emission of environmental pollutants such as etching and developing solutions can be reduced.

Seventh, it is possible to print computer-designed graphic files directly on the substrate surface in a robot-controlled mode. This eliminates the need to establish new photomasks and new process conditions for every design change.

Hereinafter, with reference to the drawings, the present invention will be described in more detail.

3 is a process flowchart illustrating a method for forming a micropattern using a direct printing method of a near field electrospinning method according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the method of forming a micropattern using the direct printing method of the near field electrospinning method according to the present invention includes preparing a electrospinning solution by mixing a material for producing a pattern in an organic solvent (S11); Discharging the electrospinning solution from the spray nozzle in a state where a voltage is applied (S12); And attaching the electrospinning solution discharged from the spray nozzle to the surface of the substrate positioned on the collector having the grounding property to form a fine pattern (S13).

The method for forming a micropattern using the near field electrospinning method according to the present invention begins by preparing an electrospinning solution by mixing a material for producing a pattern in an organic solvent (S11).

The material for pattern production may be a variety of materials such as conductive materials, organic and inorganic composites, photoresist, or insulating materials, specifically, the conductive material is a polymer selected from the group consisting of P3HT, PEDOT, PSS, PPE or collagen Nanoparticles selected from the group consisting of mercury, silver, copper and gold may be used, and organic and inorganic complexes may include organic materials such as P3HT, PEDOT, PSS or PPE, CNT, oxide or charge mobility. Composites of inorganic materials having good properties can be used. As the photoresist, a HOECHST series photoresist such as AZ-5214 or a Shipley series photoresist such as Sipley-1200 may be used. The insulating material may be Al ₂ O ₃ , SiO _2, and boron-nitride (c-BN). Such as ceramic or diamond selected from the group may be used, but is not limited thereto.

Isopropyl alcohol, DMF, THF, or water may be used as the organic solvent in which the pattern preparation material is mixed. Alternatively, an organic compound such as PVA, PEO, or PVP may be optionally used for proper dispersion.

In this case, the electrospinning solution preferably has a viscosity in the range of 30 cps or more to 500 cps or less.

Subsequently, the electrospinning solution is discharged from the spray nozzle in a state in which a voltage is applied (S12), and then the ejection from the spray nozzle is attached to the substrate surface located on the collector having the grounding characteristic to form a fine pattern (S13). )

Here, the near field electrospinning apparatus according to FIG. 4 is used. The near field electrospinning apparatus includes an injection nozzle 10 through which an electrospinning solution is discharged, a syringe 20 for discharging the electrospinning solution from the injection nozzle 10, and a power supply device 30 for applying a voltage to the injection nozzle 10. ), A ground collector 40 having a grounding characteristic relative to the voltage applied to the nozzle, and a syringe pump 50 for applying pressure to the syringe.

Therefore, the manner in which the electrospinning solution is discharged through the near field electrospinning apparatus of FIG. 4 is as follows. The electrospinning solution contained in the syringe 20 is discharged from the injection nozzle 10 by the pressure applied through the syringe pump 50 from the inside of the syringe 20 to form a small droplet in the nozzle end. At this time, the droplet is in equilibrium with the surface tension to maintain the circular and the electric field applied between the spray nozzle 10 and the ground collector 40. After that, the power supply device 30 gradually increases the intensity of the DC voltage, and when it becomes larger than the threshold potential, the balance of the surface tension and the applied voltage is broken, and the linear fluid column starts to be ejected from the circular droplet. Since the fluid is charged, conduction current flows to compensate for the discharged charge by the ejected amount. Therefore, the sprayed in the form of a charged solution, the droplets injected from the nozzle tip is not scattered by the surface tension, and adheres to the ground collector 40 at the same time by the electrostatic repulsion to the voltage applied to the needle.

Here, the injection nozzle 10 may be used having a diameter of 20 ~ 500 ㎛ made of a metal or plastic material, the syringe 20 is discharged from the injection nozzle at a rate of several ml to several μl / minute per hole (hole) What can be used can be used, the power supply 30 may be used to apply a high voltage of several tens to thousands of volts, but is not limited thereto.

In order to reduce the line width of the pattern, the end of the injection nozzle 10 may be designed in the form of a tapered tip as shown in FIG. As can be seen in Figure 5, by designing the nozzle to have a tapered-tip structure that becomes thinner toward the end, it is possible to reduce the size of the droplets generated at the nozzle end or to prevent the formation of droplets at all. . For example, it is preferable to make the size of a droplet 100 micrometers or less. The change in the size and shape of the droplets generated in the case where the tip of the injection nozzle 10 is a tapered-tip structure b and in the case of the general nozzle a is shown in FIG. 6.

The distance between the nozzle 10 and the ground collector 40 is preferably adjusted to be 3 mm or less, much closer than 5 to 30 cm, which is the distance to be maintained in the case of a general electrospinning method.

Fine patterns arranged in the desired direction at the desired position by making a fine pattern by direct writing while adjusting the distance between the nozzle and the ground collector, the moving speed of the nozzle in the XYZ direction, the applied voltage and the size of the nozzle The width of the pattern may have a line width of 20 μm or less depending on the formation conditions.

For example, using a nozzle having a tapered-tip structure as proposed in the present invention, the distance between the nozzle and the collector of the electrospinning apparatus is controlled at a distance of 500 μm to 3 mm, and the nozzle radius inside the metal tip is adjusted. 20 micrometers or less of line width by adjusting the voltage applied to a nozzle to 3-15 kV in the state small adjusted to 20 micrometers-50 micrometers, and adjusting the moving speed of a nozzle to XYZ direction at 5-15 cm / sec. It can produce a fine pattern having.

Subsequently, a step of removing residual organic solvent and other organic components after pattern formation may be performed. In this case, general methods in the art can be used, but preferably can be removed by heat treatment, plasma treatment or UV O ₃ treatment.

7 is a process diagram schematically illustrating a process of fine patterning of a printed circuit board according to an exemplary embodiment of the present invention.

The copper thin film 101 is formed on the substrate 100, and the photoresist 102 is mixed in an organic solvent on the copper thin film 101 to prepare an electrospinning solution, which is shown in FIG. 4. And the photoresist 102 is attached onto the substrate on which the copper film 101 on the ground collet is formed. Next, the copper thin film 101 is etched. Subsequently, the remaining photoresist is removed to fabricate a printed circuit board composed of only a fine patterned copper thin film 101.

FIG. 8 shows a printed circuit board having a photoresist micropattern formed before etching (a) and a printed circuit board finally manufactured by removing residual photoresist after etching.

The micropattern forming method using the near-field electrospinning direct printing method according to the present invention can be applied to highly integrated printed circuit boards, biosensors, or printed electronic circuits such as RFID and electronic paper.

1 is a view showing a comparison between a fine pattern manufacturing process by a direct printing method and a pattern manufacturing process by a conventional photolithography method.

Figure 2 illustrates a major application that can be produced by applying a direct pattern (Direct Patterning) method.

3 is a process chart showing a micropattern forming process using the direct printing method of the near-field electrospinning method according to an embodiment of the present invention.

4 is a system schematic diagram (a) and an actual device diagram (b) schematically showing the near-field electrospinning apparatus used in the manufacture of the micropattern according to the present invention.

5 is a view showing a spray nozzle designed in a tapered-tip structure in the near-field electrospinning apparatus used when producing a fine pattern according to the present invention.

6 is a view showing a change in the size of the droplets according to the spray nozzle designed in the tapered-tip structure of Figure 5, (a) is the shape of the droplets generated during the conventional electrospinning process, (b) taper-tip It shows the shape and size of the droplet by using the nozzle of the structure.

7 is a process diagram schematically illustrating a process of fine patterning of a printed circuit board according to an exemplary embodiment of the present invention.

FIG. 8 is a view showing before (a) and after etching (b) of etching a printed circuit board finely patterned by a near field electrospinning direct printing method according to an embodiment of the present invention.

Claims (9)

Preparing an electrospinning solution by mixing a pattern preparation material in an organic solvent; Discharging the electrospinning solution from the spray nozzle with a voltage applied thereto; And And attaching the electrospinning solution discharged from the spray nozzle to a surface of a substrate positioned on the collector having a grounding property to form a fine pattern. Here, the spray nozzle has a taper-tip shape in which the nozzle width becomes narrower toward the end, and the droplet size of the solution ejected through the nozzle end is controlled to within 100 μm. . delete The method of claim 1, The tapered-tip spray nozzle has a nozzle team machining angle between 20 and 45 °, a distance between the nozzle and the collector between 500 μm and 3 mm, and the material of the nozzle is Teflon, plastic or stainless steel. Micro pattern formation method using an electrospinning method. The method of claim 1, Method for forming a fine pattern using a near-field electrospinning method is isopropyl alcohol, DMF, THF or water as the container solvent for producing the electrospinning solution. The method of claim 1, In the manufacturing step of the electrospinning solution, fine pattern formation method using a near-field electrospinning method further comprises an organic compound of PVA, PEO or PVP. The method of claim 1, A fine pattern forming method using a near field electrospinning method comprising a conductive material, an organic-inorganic composite, a photoresist or an insulating material as a material for producing a fine pattern. The method of claim 6, The conductive material is a polymer selected from the group consisting of P3HT, PEDOT, PSS and PPE, or nanoparticles selected from the group consisting of mercury, silver, copper and gold, The photoresist is selected from HOECHST series photoresist or Shipley series photoresist, The insulating material is Al ₂ O ₃ , SiO ₂ and c-BN (boron-nitride) is a fine pattern forming method using an electrospinning method is a ceramic or diamond selected from the group consisting of. The method of claim 1, In order to form a fine pattern having a line width of 20 μm or less, the injection nozzle has a taper-tip structure and the inside nozzle radius is designed to be 20 μm to 50 μm, and the distance between the nozzle and the collector of the electrospinning apparatus is Fine control using an electrospinning method to adjust the distance to 500㎛ to 3mm at a short distance, to adjust the voltage applied to the nozzle to 3 to 15 kV, and to adjust the moving speed of the nozzle in the XYZ direction to 5 to 15 cm / sec Pattern formation method. The method of claim 1, After forming the fine pattern, the method of forming a fine pattern using a near-field electrospinning method further comprising the step of removing the organic solvent and residual organic components by heat treatment, plasma treatment or UV O ₃ treatment.

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