JP2014144417A - Pattern drawing device and pattern drawing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize its drawing device at a level endurable against productization, for drawing an optional pattern on-demand with high precision, by using an inkjet device, without treating a surface of a drawing object.SOLUTION: A pattern drawing device comprises at least an inkjet head 101, a stage 102, a controller 103 and a reservoir 104 for storing ink. The inkjet head comprises a discharge port for discharging the ink 105. The ink is dispersion system ink of dispersing a dispersoid particle in a dispersant, and the ink is filled in a space up to the discharge port from the reservoir. The stage comprises a heating mechanism 106 for placing the drawing object 107 and heating a drawing expected area of the drawing object to the uniform temperature, and a distance between the discharge port of the inkjet head and the drawing object is 0.5 mm-20 mm. The controller is constituted for controlling relative operation of the inkjet head and the stage.

Description

The present invention relates to a pattern drawing apparatus that draws a high-definition pattern, and a pattern drawing method that draws a pattern using the apparatus.

In recent years, various electronic device products have been diversified and product cycles have been shortened. Along with this, there is an increasing demand for making a wide variety of products in a short time. Furthermore, since it is a multi-product variety, it is not necessary to mass-produce it, and a multi-product, small-volume, short delivery time is required.

Until now, it was a mass production society, so each company's production line is also suitable for mass production. However, in response to the recent demands for various types, small quantities, short delivery times, and fast product cycles, there is no printing plate, that is, an inkjet printer that can draw arbitrary patterns on demand. There is a great expectation that it will be able to solve market demands by introducing it into the market.

Attempts to make products, especially electronic devices, using various printing technologies, including inkjet, have grown to be called the printed electronics (or printable electronics) field, and functional materials have been developed by various printing methods. Various researches have been conducted to draw an arbitrary pattern with high definition using the.

Japanese Patent No. 3948247 WO2009 / 076023

JSME International Journal Series B, Vol. 47, No. 3, (2004) pp490-496 Nanotechnology Vol.20 (2009) 165303 (pp5)

As shown in the above prior art documents, and the literature cited in the above prior art documents, etc., although research on drawing an arbitrary pattern with high definition on demand using an ink jet device has been carried out very much, Devices that have been manufactured and sold for practical use are not yet one unit even when looking at the inkjet market.

Basically, it is said that inkjet is not suitable for high-definition drawing mainly from the following two viewpoints. First, the ink used for ink jet ejection has a very low viscosity and is usually no more than 15 Pa · s, no matter how high, and spreads even after the ink has landed on the object to be drawn (Non-Patent Document 1). reference). Second, since the wetting spread depends on the surface tension (see Non-Patent Document 1), when drawing on a substrate having a different surface, for example, a metal film is formed on a part of the glass substrate, When drawing on both the glass and the metal, uniform wetting cannot be performed because the way of wetting and spreading differs depending on the surface tension of the outermost material.

Many studies have been conducted to control such “wetting and spreading” and enable high-definition pattern drawing on demand by inkjet. For example, there are a method of ejecting high-viscosity ink so that the influence of surface tension can be ignored, a method of performing surface treatment on a drawing object (hereinafter also referred to as a substrate), and controlling the wetting and spreading of the ink. Among them, as described in Patent Documents 1 and 2 described above, there are many studies on “heating an object to be drawn in advance and drawing with an ink jet”.

First, the above-described inkjet system that ejects high-viscosity ink basically increases the viscosity of the ink immediately before ejection by heating the ink inside the flow path and applying a high voltage to the drive unit. In general, discharge is performed with displacement. In this method, the ink is denatured inside the flow path by heating at a high temperature, and further, the ink is hardened and the flow path is blocked, making it impossible to discharge, or the discharge frequency is very low due to the high viscosity of the ink. (Viscous liquids cannot move quickly. For example, if the applied force is the same, candy cannot be moved as fast as water.) Not in.

In addition, research on surface treatment is very active, and it is a technology that is currently popular with academic societies, etc., but it becomes clear that it is completely useless in view of what the technology is applied to. This is because, as described above, a major purpose of high-definition pattern drawing on demand by inkjet is to produce printed electronics, that is, electronic devices using printing technology. If various functional thin films can be formed by ink jetting, it is easily imagined that a device can be manufactured in many times in a short time and at a low cost.

Electronic devices are formed by laminating various types of functional thin films. Therefore, it is possible to control the surface tension by surface treatment before the first layer to be formed first, but since the second and subsequent layers exist, the surface treatment can be easily performed. Not necessarily.

Generally, the surface treatment is roughly divided into two methods. First, a receiving layer is formed and only the ink solvent is sucked into the receiving layer to prevent wetting and spreading. Second, surface modification with chemicals is performed to prevent wetting and spreading by controlling the surface tension. It is a method. Both may be effective when the first layer is formed, but the second layer or more cannot be applied in most cases because there is a balance with the lower layer. In the first method, a receiving layer is formed between the nth layer (n> 1) and the (n + 1) th layer, and the target laminated device itself cannot be formed. The second method is chemical treatment, which is often treated with acid or alkali, and damages the layer formed before the chemical treatment. In addition, it is almost impossible to form a plurality of types of thin films and perform a chemical treatment on a drawing object having a surface of a different material. For example, when a metal film is formed on a part of a glass substrate and a chemical treatment is performed on both the glass and the metal, a chemical treatment different from the glass surface and the metal surface must be selectively performed. The more complicated the pattern that is formed, the more difficult it is to do such processing.

And, as described in Patent Documents 1 and 2, the method of “drawing an object to be drawn (substrate) in advance and drawing with an ink jet” has been established as well as the number of papers, the number of patent applications, and the like. There are many patents, so it seems reasonable. However, such an inkjet system has not yet been sold as a product by patent holders or other companies. There must be some problem that some kind of barrier is successful at least at the experimental level where papers and patents are written, but not commercialized.

It is considered that these problems are also implicitly shown in the above-mentioned Patent Document 1 to the extent that it can be understood by those skilled in the art. First, in claim 1 of the above-mentioned patent document 1, “(front omitted) a fourth step of moving the ink jet head to a position not overlapping the mounting table and cooling the ink jet head; Have been described. Further reading, in the 22nd paragraph of the twenty-second embodiment of the invention, “the inkjet head H is covered with the (omitted) cooling jacket 11 (cooling means), and the double wall of the cooling jacket 11 is connected through the pair of connection ports 13. There is a description that "the inkjet head H can be cooled with water by circulating cooling water through an internal flow path."

From this description, “ink clogging” is immediately conceived by those skilled in the art of ink jet devices.

In claim 12 of the above Patent Document 1 and inside the specification, there is a description that “the liquid (inkjet ink) contains conductive fine particles”. That is, the ink ejected from the inkjet is not a solution system but a dispersion system ink. When forming a functional thin film by inkjet, the ink used is not a solution system but a dispersion system in which particles of a functional substance are dispersed in a solvent. For example, when forming a conductive thin film, the metal is insoluble in any solvent unless it is made into a salt. Therefore, a dispersed ink in which metal particles are dispersed in a solvent is used.

Dispersed inks are very difficult to handle as inkjet inks. This is because the ink jet has a very small port (hereinafter referred to as a discharge port or an orifice) for discharging ink, and the diameter of the discharge port is 200 μm or less no matter how large. In order to form a high-definition pattern, it is necessary to further reduce the discharge port. Generally, a discharge port diameter of 20 μm or less is employed. When this ejection port is viewed from the drawing object side, the surface of the dispersed ink is exposed only slightly from the small hole. That is, since the drawing object is heated at a short distance of several tens to several hundreds of μm from the discharge port where the dispersion ink is exposed, the solvent of the dispersion ink evaporates and the dispersoid (functional substance) Only particles) remain in the discharge port. Then, the remaining dispersoid solidifies and closes the ejection port, causing “ink clogging”.

Therefore, it is expected from various descriptions that it is difficult to actually set the temperature of the heater to a high temperature that is the boiling point of the ink in the technique disclosed in Patent Document 1. This is because, firstly, in the example of Patent Document 1, there is a description that the surface treatment of the substrate is always performed before the pattern is drawn. Probably, in the configuration of this embodiment, the temperature must be set to such a low level that does not actually block the discharge port, and the heating of the substrate is “expecting suppression of wetting and spreading” of the ink. Second, in preparation for blocking, a “cleaning mechanism 14” is provided, and when the ink is clogged in the inkjet head heated by the hot plate, the ejection port must be cleaned immediately to restore ejection. Those skilled in the art can easily imagine that the heating temperature of the substrate is not so high if the blockage is such that the discharge can be recovered.

Thus, while the substrate heating is advocated as a method of drawing a high-definition pattern by inkjet while suppressing the wetting and spreading of the ink, the prior literature that is actually implemented in combination with the surface treatment of the substrate is very Many.

Japanese Patent Application Laid-Open No. 2004-133867 has been considered as an invention for heating a substrate to such an extent that ink wetting and spreading can be reliably suppressed while minimizing the influence of heat on the inkjet head. It is considered that the influence of heat on the inkjet head is greatly reduced by irradiating only the “landing area” of the ink with laser or infrared rays and heating.

The inventor of the present invention has also studied the technique described in Patent Document 2 above, but immediately encounters a physical limit or a budget limit. First, in order to draw an arbitrary pattern with high-definition ink jet, the distance (hereinafter referred to as working distance or WD) between the discharge port of the ink-jet head and the drawing object is 1 mm or less, preferably 100 μm or less. And need to be very short. Further, since the ink jet head has a certain size, referring to the “landing expected area”, the best mode for carrying out the invention of the above-mentioned Patent Document 2, as shown in FIG. Then, it is general that there is no physical space that can irradiate a laser to “an area 0.5 mm to 50 mm away from the ink landing position”.

Assume that there was such a space, and that it was possible to irradiate the planned landing area. Even with this assumption, the wavelength of the laser is a problem. Currently, lasers with various wavelengths are commercially available, but the wavelengths of lasers that can be heated differ depending on the material of the drawing object. Although the above-mentioned patent document 2 does not mention the detailed laser wavelength and the material of the drawing object, the best mode for carrying out the invention has the paragraph 33 in the paragraph “A quartz glass substrate is used as the substrate, Uses a CO2 laser ".

Of the lasers that are generally sold and can be purchased, CO2 lasers provide high output and fall into an inexpensive category, but are infrared rays with a wavelength of about 10 μm, including the quartz glass described in Patent Document 2 above. Although it is possible to heat soda glass, plastics and other resins, it is not possible to heat silicon that is often used as a substrate for electronic devices and metals that reflect light beyond visible light.

Whether or not heat is generated when light having a specific wavelength is applied is a property unique to the substance, and it is necessary to use a laser having a wavelength of about 1 μm or less for a semiconductor such as silicon and a wavelength shorter than that of visible light for a transition metal. In this way, a laser with a short wavelength is more expensive than that of one inkjet device, and in addition, when there are a plurality of ejection openings, the laser is applied to the expected landing positions of the ink ejected from each ejection opening. Irradiation is necessary. This is a very difficult optical design or installs lasers as many as the number of ejection openings, which becomes impractical in terms of budget.

On-demand high-definition pattern drawing by inkjet, which is positioned as one of printed electronics, is expected as an alternative to the photolithography process that is currently the mainstream of electronic devices. The photolithography process can form a fine pattern with high definition, but requires many kinds of very expensive apparatuses in proportion to the high definition. Printed electronics is an idea to replace the process with an inexpensive printing technology, and therefore, if many expensive lasers as described above are installed, it cannot be a substitute for photolithography.

Nevertheless, in the long history of inkjet, a great deal of research has been done on drawing high-definition patterns on demand by the technique of heating the drawing object. For example, Non-Patent Document 2 is not a research paper for high-definition drawing. This is a research paper that attempts to draw and bake simultaneously by drawing a silver salt ink pattern on a heated drawing object using an inkjet printer. Nevertheless, there is described a result that thin wiring can be drawn while suppressing the wetting and spreading by heating the drawing object to a high temperature. As described above, a lot of research on high-definition pattern drawing by ink jet by heating an object to be drawn has been a great success experimentally, even though it has a big problem for practical use. Maybe because of the fact that it has come. The inventor repeated trial and error in order to tackle the problem of practical use of the ink jet apparatus capable of high-definition pattern drawing by heating the drawing object and commercialization of the apparatus.

First, in the inkjet industry, it is considered that there is a condition (in other words, common sense) that must be satisfied in order to realize high-definition pattern drawing on demand. First, reducing the diameter of the ink droplets ejected from the ejection ports is synonymous with reducing the ejection ports themselves. Second, the working distance is shortened as much as possible, and the ejected ink is reliably landed at the target position. Thirdly, the speed of ink droplets to be ejected is not increased. This is because, as shown in the equation for obtaining Dcmax described in Non-Patent Document 1, the wetting and spreading diameter of the ink that has landed on the drawing object depends on the ejection speed of the ink. This is because the diameter of is increased.

In addition, it is necessary to take into consideration the fact that the ink droplets ejected from the ejection ports are not split and the balance between the speed of the ejected ink and the speed of the stage that moves the drawing target. The ink ejected from the ejection port is often divided into several parts depending on the ejection control method. When small sub-droplets (hereinafter referred to as satellites) are separated before and after the main droplet, the flight direction of the satellite is controlled. It is impossible to draw the target pattern when the satellite appears. Furthermore, since the speed of the ink droplets to be ejected needs to be slowed as described in the third case, if the stage for moving the drawing object moves fast, it becomes impossible to land the ink at the target position. In other words, the discharge speed and the stage speed must be reduced.

Here, the word “high definition” will be described. In this specification, the terms “high definition” and “high definition pattern” are frequently used. This definition is often determined depending on human visibility, and it is difficult to make a precise numerical value. However, the minimum size that humans can see with the naked eye on average is said to be 100 μm (refer to the Olympus website as a representative http://microscopelabo.jp/learn/025/). Therefore, in this specification, high-definition drawing refers to drawing drawn by a collection of ink droplets of 100 μm or less. More specifically, it is assumed that the landing diameter when an ink droplet is landed on the object to be drawn from the drawing apparatus is 100 μm or less.

As described above, the object of the present invention is to provide a high-definition pattern without any surface treatment for a drawing object having any surface state and without causing ink clogging even when the drawing object is heated. A pattern drawing apparatus and a pattern drawing method thereof.

The inventor considers that common sense considered necessary for realizing the above-mentioned high-definition pattern is the reason why high-definition pattern drawing by heating a drawing object is not put into practical use, The present invention was reached by breaking and introducing new technology.

The pattern drawing apparatus of the present invention that solves the above-described problems and enables high-definition pattern drawing on demand includes at least an inkjet head, a stage, a controller, and a reservoir for storing ink. The inkjet head has one or a plurality of ejection openings for ejecting ink, and the ejection openings are holes formed in a flat plate having an area of 1 square cm or more. The ink is a dispersion type ink in which dispersoid particles are dispersed in a dispersion medium, and the ink is filled from the reservoir to the discharge port. The stage has a heating mechanism for placing the drawing object and heating the drawing area of the drawing object to a uniform temperature, and the distance between the ejection port of the inkjet head and the drawing object is 0.5 mm. Above, it is 20 mm or less. The controller is configured to control relative operations of the inkjet head and the stage.

Here, the temperature at which the drawing object is heated varies depending on the system used, for example, the ink solvent, the ink concentration, the shape of the surface of the drawing object, and the like. Since it cannot be determined generally, the details will be described below in the following “Effects of the Invention”.

In the configuration of this drawing apparatus, the flat plate that pierces the discharge port is any one of transition metals, elements of Group 13 and 14 of the periodic table, or alloys thereof, polyimide, PEN (PolyEthylene Naphthalate), and PEEK (PolyEther Ether Ketone). The diameter of the discharge port provided in the flat plate is 20 μm or more and 60 μm or less.

Further, as an example of the composition of the ink used in the drawing apparatus, the dispersoid particles of the ink are nonmagnetic metal particles having an average particle diameter of 20 nm coated on the surface with a dispersant of 2 nm or more and 3 nm or less, The dispersion medium is a nonpolar chain saturated hydrocarbon, and the dispersoid concentration is 35 w% or more and 65 w% or less.

The pattern drawing method of the present invention that solves the above problems and enables high-definition pattern drawing on demand uses at least an inkjet head, a stage, a controller, and an apparatus having a reservoir for storing ink. The inkjet head has one or a plurality of ejection openings for ejecting ink, and the ejection openings are holes formed in a flat plate having an area of 1 square cm or more. The ink is a dispersion ink in which dispersoid particles are dispersed in a dispersion medium, and the ink is filled from the reservoir to the discharge port. A drawing target is placed on the stage, and the drawing target region of the drawing target is heated to a uniform temperature. Then, the inkjet head is arranged so as to be on the drawing scheduled area of the drawing object. At this time, the distance between the ejection port and the drawing object is 0.5 mm or more and 20 mm or less, the state and timing of the ink ejected from the ejection port by the controller, the relative position of the inkjet head and the stage, and the drawing object Ink is discharged from the discharge port by controlling the heating temperature.

According to the present invention, in the pattern drawing method, a pseudo substrate having the same material and the same thickness as the drawing object is disposed, the pseudo substrate is heated to the same temperature as a drawing scheduled area of the drawing object, and the inkjet head is placed on the pseudo substrate. After the ink is ejected in a period of 1 second to 600 seconds, the ink jet head is arranged so as to be on the drawing target region of the drawing object, and the ink can be ejected from the ejection port of the ink jet head. .

In this specification, discharging the ink jet on the pseudo substrate heated as described above is referred to as “preliminary discharge”.

Furthermore, in the pattern drawing method of the present invention, the (n + 1) th (n> 1) th ink droplet ejected from the ejection port is compared with the diameter when the ink droplet ejected from the ejection port has landed on the drawing object. The n-th ink droplet ejected from the ejection port is landed so as to overlap at a distance of 0.1 to 0.8 times.

In the pattern drawing method of the present invention, after the n + 1th ink droplet has landed, the (n + 1) th ink droplet is landed on the drawing object within a time period of 0.1 ms to 10 ms.

In particular, in the pattern drawing method of the present invention,
The dispersion medium of the ejected ink is dodecane, and the dispersoid of the ink is a non-magnetic metal particle having a surface coated with a dispersant of 2 nm to 3 nm, an average particle diameter of 20 nm, and the weight concentration of the dispersoid is 35 w. % To 65 w%. The n + 1th (n> 1) th ink droplet ejected from the ejection port is nth ejected from the ejection port as compared to the diameter when the ink droplet ejected from the ejection port lands on the drawing object. The n + 1th ink droplet is landed at a distance not less than 2 msec and not more than 5 msec after the nth ink droplet has landed. Land on the drawing object in time. At this time, the wiring of a high aspect ratio can be drawn by setting the temperature of the drawing object to be 130 ° C. or more and 150 ° C. or less.

Similarly, in the pattern drawing method of the present invention,
The dispersion medium of the ejected ink is tetradecane, and the dispersoid of the ink is a non-magnetic metal particle having an average particle diameter of 20 nm coated on the surface with a dispersant of 2 nm to 3 nm, and the weight concentration of the dispersoid is 35 w. % To 65 w%. The n + 1th (n> 1) th ink droplet ejected from the ejection port is nth ejected from the ejection port as compared to the diameter when the ink droplet ejected from the ejection port lands on the drawing object. The n + 1th ink droplet is landed at a distance not less than 2 msec and not more than 5 msec after the nth ink droplet has landed. Land on the drawing object in time. At this time, the wiring of the high aspect ratio can be drawn by setting the temperature of the drawing target to 170 degrees or more and 190 degrees or less.

The effect of the present invention seems to be difficult to understand only by the above-mentioned "means for solving the problem", so that it will be explained with reference to the principle of the physical phenomenon caused by the means as an aid for understanding the effect. To do. Of course, the means for solving the problems of the present invention and the physical phenomena described as the explanation thereof are not completely elucidated, and there is no denying the possibility that other interpretations may exist. Therefore, the present invention is not limited by the following phenomenology. However, the effect of the present invention can be obtained by executing means for solving the problems of the present invention.

The configuration of the present invention described in the above “Means for Solving the Problems” is to review the common sense of the inkjet system for high-definition pattern drawing described in the “Problems to be Solved by the Invention” and to come up with a new configuration. The problem is solved.

The pattern drawing apparatus according to the present invention includes the first “reducing the ink droplet diameter (reducing the discharge port)”, the second “reducing the working distance”, the third, which are cited as common sense of high-definition pattern drawing. It has a structure that is against all of the “slow ink drop speed”. That is, the pattern drawing apparatus of the present invention uses an ink jet head that has a larger discharge port diameter, a longer working distance, and a faster ink droplet speed, as compared to a conventional high-definition pattern drawing ink jet system.

Specifically, in the present invention, the diameter of the discharge port of the ink jet head is set to 20 μm or more and 60 μm or less, preferably 30 μm, which is much larger than that generally sold and used for high-definition drawing. As a result, the mass of the ink droplets ejected at a time becomes large, and the ink droplets can be ejected linearly far at a high speed by the mass and inertia. Therefore, the working distance, which has been said to be several hundred μm at the maximum, can be increased to 20 mm.

Furthermore, by forming the discharge port on a flat plate made of metal, it is less susceptible to heat than other materials. Metals tend to be considered to warm easily due to their high thermal conductivity, but because they reflect infrared rays, there is no temperature rise due to radiant heat from the stage or drawing object, and temperature rise near the discharge port can be suppressed. (The flat plate having the discharge port is hereinafter referred to as an orifice plate). Accordingly, it is possible to avoid the problem that the dispersoid of the dispersed ink is hardened at the discharge port due to heat from the stage and the ink is clogged. Further, by increasing the size of the orifice plate of 1 square centimeter, the entire inkjet head is also increased, and the thermal capacity of the inkjet head is increased, so that the temperature rise of the entire inkjet head can be suppressed.

However, that alone does not mean that high-definition patterns can be drawn. What is important with the ink jet head is the composition of the ink.

The ink filled in the pattern drawing apparatus of the present invention needs to be a dispersed ink in which particles are dispersed. For example, J. Magn. Magn. Mater., 125 263 (1993) and the homepage compiled by the first author of the paper “Study on Dispersibility of Magnetic Particles in Magnetic Coatings for Magnetic Recording Media” (http: // hr -inoue.net/zscience/doctor/d-chapter3/d-chapter3.html) As you can see from Chapter 3 etc., the dispersion system has a correlation between the dispersoid weight concentration and viscosity, and the correlation is low. The concentration is linear, but rises rapidly with a high-order function at a certain concentration. The cited reference is a magnetic particle dispersion system, and it is stated that the viscosity rapidly increases from about 20 w% because the magnetic particle dispersion system has an interaction between particles.

Ann. In. Phys., 19, 289 (1906), etc., further cited in the above document, describe a spherical fine particle dispersion system without interaction. Many studies have been conducted on non-interactive dispersions in addition to this document, and depending on the dispersion solvent and particle size of the dispersoid, the viscosity increases rapidly at a higher concentration than the magnetic particles. I know. For example, when metal particles having a diameter of about 20 nm are dispersed in a nonpolar solvent, the viscosity rapidly increases at 50 to 60 w%.

That is, the viscosity of the dispersed ink increases linearly and gently up to a certain density, but rapidly increases in a high-order function at a certain point. Therefore, if the drawing object is heated, the ink droplets that have landed on the drawing object rapidly increase in viscosity due to the evaporation of the solvent, and the solvent drops depending on the temperature of the heated drawing object. When the vapor pressure is reached, an equilibrium state is reached.

In the pattern drawing apparatus of the present invention, it is possible to use ink in which dispersoids having various functions are dispersed, but all of them use ink prepared to a weight concentration before the viscosity rapidly increases. preferable. Thereby, various effects suitable for high-definition drawing can be obtained.

In particular, the case of observing each ink drop will be described with reference to FIG. As shown in FIG. 6A, the moment when the ink droplet 601 ejected from the ejection port of the inkjet head has landed on the drawing object 602 is hemispherical. When this hemispherical shape is viewed microscopically, the thinner end portion (arrow 604) has a larger surface area with respect to the volume than the raised center portion (arrow 603), so the evaporation rate of the solvent is faster and the viscosity is higher. The speed at which is increased is also fast. Therefore, since the end 604 of the landed ink droplet 601 is dried fastest and is fixed to the drawing target 602, the landing width of the ink indicated by the double arrow 605 in FIG. 6A can be suppressed.

As described above, the relationship between the weight concentration and the viscosity related to the particle dispersion system has been known for a long time as can be seen from the oldness of the cited document. The technique of drawing a high-definition pattern has been discovered by the inventors of the present invention. This is because the conventional ink jet system has a common sense that the shorter the working distance, the higher the resolution can be drawn, and the dispersion ink prepared so that the viscosity is rapidly changed by the heat of heating the substrate is used. Because I couldn't.

As described above, the pattern drawing apparatus according to the present invention uses the above-described ink jet head having a long working distance to avoid ink clogging at the ejection port of the ink jet head due to heat, and utilizes the property that the viscosity changes depending on the concentration of the dispersion system. Ink prepared so that the viscosity rapidly increases when the concentration of the dispersoid in the ink droplets increases as the solvent evaporates is used. In addition, by suppressing the wetting and spreading of the ink droplets landed by heating the drawing object, high-definition patterns can be drawn without any surface treatment for controlling the wettability of the drawing object. A drawing apparatus can be realized.

Further, the change in physical properties including the viscosity of the dispersed ink seems to be able to control the spreading direction of the ink landed on the drawing object because the drawing object is heated.

As a simple model, the second ink droplet is landed on the drawing target so as to slightly overlap the first landed ink droplet. The third ink droplet is landed on the second ink droplet so as to overlap with the second ink droplet, and this is repeated, so that the nth ink is overlapped with the n−1th (n> 2) ink droplet. Make a drop land. The case where the (n + 1) th ink droplet is landed so as to overlap with the nth ink droplet and a straight line is drawn will be described with reference to FIGS. 6 (b) and 6 (c). First, the nth ink droplet 606 overlaps the (n−1) th ink droplet 608 and lands on the drawing target 602, and then the (n + 1) th ink droplet 607 overlaps the nth ink droplet 606. When landing on the object to be drawn, the nth ink droplet 606 becomes the (n−1) th ink droplet 608 or the (n + 1) th ink droplet 608 as shown by one of the two arrows in FIG. A phenomenon of anisotropic flow to either ink droplet 607 is observed.

FIGS. 7A and 7B show how this was observed experimentally. In FIG. 7A, it can be seen that the nth ink droplet is flowing toward the (n-1) th ink droplet side. In contrast, in FIG. 7B, the nth ink droplet appears to flow toward the (n + 1) th ink droplet. Such a phenomenon seems to change depending on various factors such as ink density, ink droplet size, landing interval and landing time, and no clear cause is known.

Presumably, due to the drawing object 602 being heated, the dispersion medium suddenly evaporates from the landed ink droplets. When the nth ink droplet 607 lands there, the content of the dispersion medium in the (n + 1) th ink droplet 607 is larger than that in the nth ink droplet 606 at the moment when the (n + 1) th ink droplet 607 is landed. There are many. Thus, when the nth ink droplet 606 and the (n + 1) th ink droplet 607 having different physical properties within a minute time difference come into contact with each other, the nth ink droplet 607 is not isotropic and has the same composition. It is expected that it will tend to flow anisotropically toward the ink droplet side close to.

Various phenomena are considered for the phenomenon that the nth ink droplet flows to the (n−1) th ink droplet side or the (n + 1) th ink droplet side, but various physical properties including viscosity are considered. It is very difficult to prove a clear principle because it is a dynamic phenomenon that flows while fluctuating and a very small system. There are two principles that are anticipated by the inventors as follows.

First, as described above, at the moment when the (n + 1) th ink droplet has landed, the density of the nth ink droplet is higher than that of the (n + 1) th ink droplet. As described above, the viscosity of the dispersion increases as the concentration increases, but the surface tension tends to increase as well. That is, the concept is that the (n + 1) th ink droplet has a lower surface tension than the nth ink droplet, and therefore flows toward the (n + 1) th ink droplet having a higher surface tension.

Second, at the moment when the (n + 1) th ink droplet has landed, the temperature at which the nth ink droplet has landed is slightly reduced due to the removal of the heat of vaporization that volatilizes the solvent contained in the nth ink droplet. If the (n + 1) th ink droplet lands immediately there, the nth ink droplet is considered to have a lower temperature than the position where the (n + 1) th ink droplet landed. Conversely, if the (n + 1) th ink droplet lands after the nth ink droplet has landed and warmed up sufficiently, the (n + 1) th ink droplet landed more than the landed portion of the nth ink droplet. There is a possibility that the temperature at the position is lower due to the influence of the ink temperature. Liquids have the property of flowing from higher to lower when there is a temperature difference (called Marangoni flow). This flow is considered to flow in order to make uniform a small temperature difference in the dispersion, or to flow due to a difference in surface tension due to the temperature difference.

Regardless of which principle is adopted, when the ink droplets ejected from the inkjet head are landed so as to overlap with the pattern drawing device of the present invention, it is possible to draw thin lines by controlling the wetting spread anisotropically. As a result, it is possible to realize an apparatus that draws a high-definition pattern without performing surface treatment of the drawing object.

Further, the effect of the pattern drawing method of the present invention will be described. In the pattern drawing method of the present invention, drawing may be performed by a normal procedure using the pattern drawing apparatus of the present invention, but it is preferable to draw on a drawing object after ejecting an ink jet on a pseudo substrate.

When the ink-jet head is placed on a drawing object heated from a state where it is held at room temperature, the ink-jet head is affected not only by the ambient temperature change but also has a significant effect on ejection. Although the magnitude of this influence depends on the configuration of the ink jet apparatus, the method of the present invention is adopted because it cannot be completely eliminated even with the configuration of the pattern drawing apparatus of the present invention.

In the pattern drawing method of the present invention, in order to eliminate the influence of the temperature change around the ink jet head, the ink jet head and the discharge reach a thermal equilibrium while discharging on the pseudo substrate heated at the same temperature as the drawing object. Wait for. Then, after ink ejection is stabilized, the pattern is drawn by changing the relative position so that the inkjet head is placed on the drawing object heated to a predetermined temperature. Stable drawing can be realized without being affected.

This can be realized because of the structure of the drawing apparatus having an ink jet head that minimizes the influence of heat according to the present invention, and in the case of an ink jet that has a short working distance and a small discharge port diameter that is normally used, thermal equilibrium is achieved. Ink clogging occurs before reaching discharge, making ejection impossible. That is, the pattern drawing method of the present invention is realized by the pattern drawing apparatus of the present invention.

As described above, by using the pattern drawing apparatus and the pattern drawing method of the present invention, an arbitrary pattern can be drawn in high definition without any surface treatment on any substrate. Furthermore, by devising a drawing method, it is possible to form fine wiring with a high aspect ratio, which has been said to be impossible with an ink jet drawing apparatus until now.

As described above, the present invention is formed by intertwining very complicated physical phenomena. However, since the configuration itself is very simple, it is not at an experimental level as in the past, but withstands practical use and commercialization. A great effect of realizing an inkjet drawing apparatus that can be obtained is obtained.

It is a figure explaining the typical structure of the pattern drawing apparatus of this invention. It is a figure explaining the inkjet head which comprises the pattern drawing apparatus of this invention. It is a figure explaining one Embodiment of the pattern drawing apparatus of this invention. It is a figure explaining one Embodiment of the pattern drawing method of this invention. It is a figure explaining one Embodiment of the pattern drawing method of this invention. It is a figure explaining the phenomenon seen with the pattern drawing apparatus of this invention. It is a top view of the SEM image (image image | photographed with the scanning electron microscope) of the line drawn using the pattern drawing apparatus of this invention. It is a figure which shows the example of the voltage pulse applied to the drive part of an inkjet head. It is the top view (a) and sectional drawing (b) of the SEM image of the line drawn using the pattern drawing apparatus of this invention. It is the top view (a) and sectional drawing (b) of the SEM image of the line drawn using the pattern drawing apparatus of this invention.

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following description. It will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments given below. Note that in describing the structure of the present invention with reference to the drawings, the same portions are denoted by the same reference numerals in different drawings.

(Embodiment 1)
First, the most basic embodiment of the pattern drawing apparatus of the present invention is shown in FIG. The pattern drawing apparatus of the present invention includes at least an inkjet head 101, a stage 102, a controller 103, and a reservoir 104 that stores ink 105.

First, ink jets are roughly classified into two types depending on the ejection method. One is often called a continuous type and the other is called a drop-on-demand type. In continuous ink jet, ink is ejected continuously, and the ink is landed on an object to be drawn by bending its orbit as necessary. Unnecessary ink is collected, circulated through the apparatus, and ejected again. On the other hand, in the drop-on-demand method, control is performed so that ink is ejected only when drawing is desired. Accordingly, all of the ejected ink lands on the drawing object.

The ink jet used in the pattern drawing apparatus of the present invention is a drop-on-demand ink jet. Ink jet heads used for the drop-on-demand ink jet include various ejection methods. For example, there are a valve system that controls ejection by an electromagnetic valve, a thermal system that ejects ink by using volume expansion when the ink is heated, and a piezo system that ejects ink by using displacement of a piezoelectric element (hereinafter also referred to as piezo). The piezoelectric method is classified into a bend mode, a push mode, a share mode, and the like depending on how the displacement of the piezoelectric element is used.

Although each has its own characteristics, the thermal mode and piezo mode share mode has been developed to enable high-resolution drawing by ejecting fine droplets because the structure can be made finer. Is. Therefore, long-distance flight of ink droplets required for the configuration of the present invention cannot be expected. Further, since the thermal method heats the ink to the boiling point, it cannot be applied to the ink jet of the present invention using a dispersed ink.

Accordingly, the inkjet head constituting the present invention is a general inkjet head other than the thermal method, and any method can be used as long as the flight distance can be obtained long. Such ink jet heads are widely used as industrial ink jet printers, not home ink jet printers.

The ink jet head may have one ejection port or a plurality of ejection ports. For example, the appearance of an inkjet head is shown in FIG. The inkjet head 203 of the industrial inkjet printer described above varies from one having a discharge port 202 to 7, 8, 32, 128, 500, 600, and more. The discharge port 202 is formed by a hole made in the flat plate 201. FIG. 2 shows an example in which eight discharge ports 202 are provided.

In the present invention, the flat plate (also referred to as an orifice plate) provided with the discharge port is a transition metal (for example, iron or titanium), a periodic table 13 group or 14 group element (for example, silicon or tin), or an alloy thereof ( For example, it is composed of any one of steel steel called SUS in the JIS standard.

However, it is difficult to make a small hole in a hard material such as metal or silicon in terms of processing technology. Of course, there is nothing that cannot be done if the machining cost is ignored as in the case of electric discharge machining, but it is contrary to the concept of an inexpensive device configuration and process required by printed electronics. Therefore, in view of ease of processing, the orifice plate provided with the discharge port may be a plastic plate having excellent heat resistance, such as polyimide, PEN (PolyEthylene Naphthalate), PEEK (PolyEther Ether Ketone), or the like. When such a plastic plate is used, a very thin metal film may be deposited on the outermost surface so that the temperature of the orifice plate does not rise due to radiant heat from the drawing object. Thereby, the said metal film reflects infrared rays, and can suppress the temperature rise of an orifice plate.

There is a reservoir 104 for supplying ink 105 to the inkjet head. The reservoir is an ink tank that stores ink, and this may be separated from the inkjet head and connected from the reservoir to the inkjet head with an ink supply tube, or the reservoir and the head are integrated to form the reservoir. A replaceable cartridge system may be used.

FIG. 1 shows the configuration of a pattern drawing apparatus in which the inkjet head 101 and the reservoir 104 are separated. In this case, the discharge port of the ink jet head 101 and the level of the liquid level of the ink contained in the reservoir 104 need to be substantially the same (as indicated by the dotted line in the figure). Preferably, the ink level is slightly lowered by about 0.05 mm to 0.2 mm. This is because if the ink level is significantly lowered, air is sucked from the ejection port and ink is not ejected from the inkjet head 101. Conversely, if the ink level is made higher than the ejection port, the ink is discharged from the ejection port. This is because it leaks. By making the liquid level of the ink and the ejection port the same (or slightly lowering the liquid level), an ink meniscus is formed in the ejection port, and good ejection performance can be obtained. When the ink jet head and the reservoir are integrated, it is preferable to control the inside of the reservoir to a negative pressure so that ink does not leak from the ejection port.

FIG. 2 shows an inkjet head when the reservoir is installed separately from the inkjet. In this case, a supply port 204 through which ink is supplied from the reservoir is provided. As described above, in the case of a structure in which ink is supplied from the outside, when ink is added, added, or replaced, a large amount of air may be mixed in the ink flow path to cause ejection failure. In preparation for such a case, the inkjet head 203 is preferably provided with an ink outlet 205 for discharging air together with ink. Of course, the apparatus of the present invention may use an ink jet head that is not provided with the ink discharge port 205.

Returning to the description of FIG. 1, the stage 102 has a structure on which the drawing object 107 can be placed. The stage 102 has a heating mechanism 106 such as a heater inside, and can heat the drawing object 107 to a uniform temperature. FIG. 1 shows a diagram in which a flat drawing object 107 is placed on a flat stage 102.

The structure of the stage 102 depends on the shape and material of the drawing object. For example, when the drawing object is flat and has a certain thickness and weight, such as a glass plate or a silicon wafer, the stage only needs to have a heating mechanism such as a hot plate with a flat top surface. If the drawing object is soft and can take any shape like PET, polyimide, PEN, or PEEK film, the stage has a mechanism that can fix the drawing object such as a pin or a vacuum chuck. It is preferable that a heating mechanism that keeps a uniform temperature in close contact with the drawing object is provided.

FIG. 3 shows an example of an apparatus configuration for realizing a method called roll-to-roll (sometimes described as R2R) which is frequently discussed in the printed electronics field. Roll-to-roll is a method of continuously drawing a flexible substrate 301 (which may be described as having flexibility) by a winding method. In such an apparatus configuration, the stage 102 can be provided with a mechanism for supporting the winding substrate, a heating mechanism for supporting the drawing scheduled area, and heating the drawing area uniformly.

The pattern drawing apparatus of the present invention has the above-described ink jet head and stage arranged at appropriate positions, and the distance (working distance) between the ink discharge port of the ink jet head and the drawing object placed on the stage. ) In the range of 0.5 mm to 20 mm.

The working distance is not fixed in general, and other conditions such as the size of the ejected ink droplet, the speed of the ink droplet, the temperature of the drawing object, the composition of the ink, the ink It is necessary to decide in consideration of various conditions such as concentration.

For example, there is a correlation between the size and speed of the ink droplet, and the speed tends to increase as the ink droplet size increases. If the ink droplet speed is fast and the straightness is high, a large working distance can be obtained. If the temperature of the drawing object is high, it is necessary to increase the working distance in order to suppress the influence of heat on the ink jet head. Ink composition and density are also related to ink drop velocity. If the specific gravity of the dispersoid of the dispersed ink is high, the mass of the ink droplet is increased and the speed is increased, so that a large working distance can be obtained. That is, it is very important to determine an appropriate working distance depending on what drawing object and what ink are used and how many times the drawing object is set.

For ink, it is determined by the dispersoid concentration and viscosity. As described in the above “Effects of the Invention”, the viscosity of the dispersion system increases linearly and gently up to a certain weight concentration, but rapidly increases in a high-order function at a certain point. In the present invention, it is preferable to use an ink prepared to a concentration immediately before the viscosity rapidly increases.

The changing point of the viscosity increase varies depending on the nature of the dispersoid, the particle diameter, and the type of the dispersion medium, and thus cannot be defined unconditionally. For example, in the case of a dispersoid having an interaction such as a magnetic substance, it is around 20 w%, and in the case of a metal or polymer having no interaction, it depends on the particle size, but in the case of a diameter of 20 nm, it is around 50 w% to 60 w%. It has been reported that viscosity often increases.

This depends on the area where the dispersoid is in contact with the dispersion medium. Since the surface area per weight increases as the particle size of the dispersoid decreases, generally the contact area with the dispersion medium increases and the viscosity increases. In addition, when a polar solvent is used as the dispersion medium, it is considered that interaction with the dispersoid may occur.

Furthermore, the surface area of the dispersoid needs to consider not only the surface area of the dispersoid itself but also the thickness of the dispersant when a dispersant is arranged on the surface in order to uniformly disperse the dispersoid in the dispersion medium. . For example, metal nanoparticles that are frequently used in the printed electronics field in recent years will be described as an example. The metal as a dispersoid has a specific gravity 10 times or more heavier than that of the dispersion medium, and the metal particles as they are hardly disperse in the dispersion medium. Therefore, the surface of the metal particles is coated with a dispersant so that even if there is a large difference in specific gravity between the dispersoid and the dispersion medium, the metal particles are uniformly dispersed. Although the thickness of this dispersing agent changes with kinds of dispersing agent to be used, it is said that the thickness of the dispersing agent which disperse | distributes metal particles is about 2 nm or more and about 5 nm. Therefore, if the diameter of the metal particles is 20 nm and the thickness of the dispersant is 3 nm, the surface area of the dispersoid must be calculated as 26 nm.

Here, it should be noted that the ink density cannot be determined only under the condition that the viscosity is immediately increased. This is because the drop-on-demand ink jet head constituting the present invention generally cannot eject unless the viscosity is in the range of 8 to 18 cps, preferably 12 to 15 cps. Accordingly, it is desirable to determine the concentration of the ink to be used by measuring the correlation between the concentration and the viscosity when preparing the ink in consideration of the specifications of the ink jet head to be used.

Next, the controller 103 of the pattern drawing apparatus of the present invention is for controlling the operations of both the inkjet head 101 and the stage 102. In the present invention, the configuration of the controller 103 is also very important. This is because the pattern drawing apparatus of the present invention can draw an arbitrary pattern with high definition. Although high definition has been described above, in order to draw an arbitrary pattern, it is necessary to control the relative position between the ejection of the inkjet and the stage.

For example, as shown in FIG. 1, when the stage 102 on which the inkjet target 101 is fixed and the drawing target 107 is placed is movable, the controller 103 moves the stage to a specific position according to the drawing data. It must be controlled to eject ink instantaneously. In this case, the stage is controlled to move in the two axes of the X-axis and Y-axis, or in addition to the rotation θ direction, thereby moving the drawing target position of the drawing object directly below the inkjet head.

In addition, the inkjet head may be movable along the X axis and the stage along the Y axis (or the opposite axis). In this case, the controller controls the position of the inkjet head, the position with the stage on which the drawing target is placed, and the ejection of ink from the inkjet head.

Furthermore, when the drawing object cannot be moved for some reason, for example, in the case of the roll-to-roll method shown in FIG. 3 in the above example, the inkjet head 101 is moved along two axes, the X axis and the Y axis. There is a need for a head drive mechanism 302 that is movable in the direction, or in addition to the direction of rotation θ. At this time, the stage controls the movement of the ink jet, the ejection of the ink, and the heating of the drawing object on the stage. At this time, the stage may have a function of only the placement of the drawing object and the heater, and when the area of the drawing object is large, the latest drawing area can be heated to a predetermined temperature. You may have a function to move.

As in the above example, the pattern drawing apparatus of the present invention can take various forms. Among these, the structure of the inkjet fixing illustrated using FIG. 1 is preferable. This is because a drop-on-demand ink jet head is vulnerable to external force, that is, acceleration when moving, and there is a concern that when it receives an impact, air enters from the ejection port and ink cannot be ejected.

However, when the drawing object is very large, it is unrealistic to move a large stage with a large stroke, and the pattern drawing apparatus of the present invention must take various forms depending on the shape and size of the drawing object. Absent. At that time, speed control when the inkjet head is movable is effective in avoiding ejection failure. In order to prevent large acceleration from being applied to the ink-jet head, when moving the ink-jet head, the speed is gradually increased over a certain period of time during start-up, and then maintained at a constant speed, and then gradually over a certain period of time when stopped. Control to decelerate. Thus, when moving the inkjet head, the controller needs to be configured to control such speed adjustment of the inkjet head.

As described above, the pattern drawing apparatus of the present invention includes at least an ink jet head, a stage, a controller, and a reservoir for storing ink. Then, the pattern drawing apparatus of the present invention is filled with a dispersed ink having an appropriate concentration and viscosity, and the drawing object is uniformly heated to an appropriate temperature, and the distance between the inkjet head and the drawing object is set appropriately. An arbitrary pattern can be drawn with high definition by setting the distance to a small distance and controlling the relative position between the drawing object and the inkjet head and the ejection of ink from the inkjet head by the controller.

Furthermore, in the pattern drawing method of the present invention, it is preferable to draw on the drawing object after ejecting the ink jet on the pseudo substrate. Specifically, the pattern drawing method of the present invention includes an inkjet head and an inkjet head that are ejected on a pseudo substrate having the same material and the same thickness as the drawing object and heated to the same temperature as the drawing object. Wait until the ink discharge from the ink reaches thermal equilibrium (preliminary discharge). Then, after ink ejection is stabilized, the inkjet head is placed on the drawing object and drawing is performed.

Various methods can be adopted as an apparatus configuration for performing the preliminary discharge. For example, as shown in FIG. 4, the drawing object 107 and the spare substrate 401 are installed on the stage 102, and the drawing object 107 and the spare substrate 401 are heated to a predetermined temperature. First, the inkjet head 101 is placed on a heated spare substrate 401 and preliminary ejection is performed (FIG. 4A). Then, after the inkjet head and the discharge are constructed as a system including the influence of the surrounding heat, the inkjet head 101 is arranged so as to come onto the heated drawing object 107 (FIG. 4B). )). As a matter of course, it is preferable to arrange the ink jet head so that the working distance when performing preliminary ejection and when performing drawing are the same.

Further, when there is no space for placing the spare substrate on the stage, for example, when the drawing object is very large, the first stage 501 for placing and heating the spare substrate 401 as shown in FIG. And a second stage 502 on which the drawing object 107 is placed and heated, and preliminary discharge (FIG. 5A) and drawing (FIG. 5B) can be performed on different stages. It is. As described above, the pattern drawing method of the present invention can realize stable drawing without being affected by the heat from the stage or the drawing object by performing preliminary discharge.

(Embodiment 2)
Next, the embodiment of the pattern drawing apparatus used by the inventor for carrying out the present invention will be described in more detail. The configuration of the pattern drawing apparatus shown in the present embodiment is merely a specific example for carrying out the present invention, and the present invention is not limited only by the contents of the embodiment, and is within the range conceived by those skilled in the art. If so, it can be easily changed.

First, as the inkjet head 101 shown in FIG. 1, a “piezoceramics driven drop-on-demand type 32ch head” used in the capital letter printer HQ series by an inkjet printer manufactured by Kishu Giken Kogyo Co., Ltd. was used. In the product catalog of Kishu Giken Kogyo Co., Ltd., the ink jet head has only two specifications of 1 nozzle 3 holes or 1 nozzle 6 holes, but in this embodiment, an ink jet head of 1 nozzle 1 hole is used. did.

Here, 1 nozzle 3 hole means that 3 discharge ports are formed in one discharge portion. This is a form that is often used in industrial inkjet systems, and is intended to make more ink appear by providing a plurality of holes in one ejection part, thereby making the printing appear darker. In this embodiment, since it is not used for such an application, a one-nozzle one-hole inkjet head in which one ejection port is provided in one ejection section as shown in the inkjet head of FIG. 2 is adopted. doing.

The orifice plate of the ink jet head and the ink flow path are formed using a steel steel alloy flat plate defined as SUS304 in JIS standards. The orifice diameters were 50 μm and 34 μm.

As shown in FIG. 1, since the ink jet head is used in a manner in which the ink jet head 101 and the reservoir 104 are separated, a screw bottle type reservoir is prepared separately. The reservoir is divided into a main body and a lid so that ink can be replenished, and the main body is made of glass so that the remaining amount of ink can be seen at a glance. The reservoir and the inkjet head are connected by a liquid feeding tube, and the reservoir to the inkjet head are filled with ink. Further, as shown in FIG. 2, the ink jet head is provided with a discharge port 205 for facilitating removal of mixed air.

Next, the stage 102 shown in FIG. 1 was manufactured by fixing a vacuum chuck with a ceramic heater on which a drawing object 107 can be placed and fixed on a commercially available XY axis automatic linear stage (manufactured by Suruga Seiki). The ceramic heater is sandwiched between alumina with low thermal conductivity to improve temperature uniformity, and the vacuum chuck is provided with a fine hole on the surface to fix the drawing object by connecting a mini pump and reducing the pressure. ing. The automatic linear stage, which is the drive unit, should select the performance and size according to the accuracy of the pattern to be drawn and the size of the drawing object. In this embodiment, the ball guide stepping having a moving distance of 200 mm on both axes. A motor type was adopted.

The drawing object 107 placed on the stage can be a glass substrate, a silicon substrate, or a flexible substrate that is attracting attention in the printed electronics field, for example, a plastic substrate such as polyimide, PET, or PEN. Furthermore, in this embodiment, no surface treatment is performed on any of these drawing objects. Of course, if the surface of the object to be drawn is contaminated with dust or the like, a high-definition pattern cannot be drawn. In such a case, cleaning with purified water or an organic solvent may be performed as appropriate.

The ink used was a silver nanoparticle ink “KGK NANO AGK101” manufactured by Kishu Giken Kogyo Co., Ltd., and a high-density ink produced in a similar manner. The ink dispersoid uses silver particles having a diameter of about 20 nm, and the dispersion medium uses dodecane. The silver particles are coated with a dispersant that can be easily dispersed in an oil-based dispersion medium such as dodecane, and the thickness of the dispersant is about 2 to 3 nm.

As described in the embodiment, it is most preferable to use ink that is adjusted to a concentration before the viscosity rapidly increases due to an increase in the concentration of the dispersoid. However, the viscosity as a discharge condition of the inkjet head must also be taken into consideration. It has been found that when the dispersoid concentration is increased, AGK101 exceeds the viscosity that can be ejected by the inkjet head before the viscosity rapidly increases. Therefore, AGK101 emphasizes the specifications of the ink jet head, and the concentration is set to 35% by weight, which is much before the viscosity increases. The prototype ink had a concentration of 65 w% that satisfies the specifications of the ink jet head just before the viscosity suddenly increases due to the concentration, although it is a similar preparation.

In the present embodiment, as shown in FIG. 1, the inkjet head 101 is fixed, and the pattern is drawn by moving the stage 102. Therefore, the controller 103 controls the relative position between the inkjet head and the drawing object, the ink ejection timing, and the ink ejection itself. To control the relative position, the controller of the above XY axis automatic linear stage made by Suruga Seiki is used, and for ink ejection control, an ink jet printer made by Kishu Giken Kogyo Co., Ltd. The controller HQ5100 was used, and for the discharge timing control for drawing the pattern, a controller was prepared to count the stepping pulse of the XY axis automatic linear stage and control the ink to be discharged when moving to a specific coordinate. . In the present embodiment, some modifications are made in order to link them, but this can be easily realized if there is knowledge of general electric circuits.

In the present embodiment, the configuration of ink ejection control and its observation will be described. In order to draw a high-definition pattern, it is necessary to control the ink droplets ejected from the inkjet head to be stable and free from secondary droplets (satellite). In order to control the ejection of droplets, it is known to devise various voltages applied to the drive unit of the inkjet head. For example, as shown in FIG. 8 (a), a double pulse in which a voltage is applied twice and a triple pulse in which a voltage is applied in three times as shown in FIG. 8 (b) are well known. . In the double pulse and triple pulse, the applied voltage, application time, application interval, and the like can be arbitrarily changed. In addition, as shown in FIG. 8C, there is a method of changing the potential before and after the applied voltage. In particular, as shown in FIG. 8C, it is also possible to control the ink droplet by intentionally delaying the rise time and the fall time when the voltage is applied. In the present embodiment, the ink is ejected with a single pulse as shown in FIG. The voltage was 17-18 V, and the voltage application time was 17-20 μsec.

In order to confirm whether or not the ejection of ink droplets from the inkjet head is unstable due to the influence of heat from the heated drawing object, a ejection observation mechanism is provided. This is to observe ink droplets ejected from an inkjet head by arranging a camera on one side and a light source on the opposite side on the other side of the inkjet head. In this embodiment, a general USB camera is used as a camera and a white LED is used as a light source. By synchronizing the ink ejection pulse of the inkjet head and the light emission timing of the LED, the ejected ink droplet can be observed. Specifically, ink is ejected from the inkjet head at the falling edge of the pulse shown in FIG. By causing the LED to emit light at an arbitrary time after the fall, it is possible to observe the shape of the ink droplet after the arbitrary time from the discharge with the discharge observation mechanism.

The state where the ink ejection is unstable means that the satellite is generated as described above, and that the same position is always observed when a number of ink droplets after an arbitrary time are observed using the ejection observation mechanism. Ink drops are observed, and they appear to be stationary or appear to be flying in the same orbit.

In particular, in the present embodiment, a pattern drawing apparatus resistant to heat can be realized, but the ink ejection performance from the ink jet is affected by heat. For this reason, in this embodiment, an ink jet head is arranged on a heated drawing object or a pseudo substrate so that ink is ejected, and the ejection state at that time is observed with a camera.

The above is the embodiment of the pattern drawing apparatus that realizes the high-definition drawing of the present invention.

(Embodiment 3)
Next, the pattern drawing method of the present invention in which the inventors have drawn a high-definition pattern using the configuration of the pattern drawing apparatus shown in the second embodiment will be specifically described. The pattern drawing method shown in this embodiment is merely a specific example for carrying out the present invention, and the present invention is not limited only by the contents of the embodiment, and is within the scope conceived by those skilled in the art. It can be changed easily.

The pattern drawing method of the present invention is arranged such that the inkjet head is placed on the heated drawing object and the stage is moved (or the inkjet head and the drawing) in the pattern drawing apparatus shown in the second embodiment. An arbitrary pattern is drawn by controlling the ejection of ink (while changing the relative position with the object). Although details have not been described in the configuration shown in the second embodiment, in the present embodiment, the inkjet head is moved and arranged on the drawing target. However, you may operate so that a drawing target object may be arranged under an inkjet head by moving a stage to the bottom of an inkjet head.

In the present embodiment, the case where the AGK 101 described in the second embodiment and the prototype ink are used and the drawing object is a glass substrate will be described. The AGK 101 has a low dispersoid concentration as described in the above embodiment. Therefore, there is a tendency to spread easily after landing on the drawing object. On the contrary, the prototype ink hardly wets and spreads when landing on the drawing object. Even in such a case, a technique for realizing high-definition drawing immediately comes up with a change in the temperature of the drawing object. In the case of using the AGK 101 that easily wets and spreads, it is considered that if the temperature of the drawing object is raised, the volatilization of the dispersion medium can be promoted and the wetting and spreading can be suppressed.

However, the method of changing the drawing object temperature in the experiment cannot obtain a dramatic effect. If the temperature of the object to be drawn was raised too high, the dispersion medium would suddenly boil and a beautiful pattern could not be obtained. From this, it is considered that the set temperature of the drawing object depends on the properties of the dispersion medium used in the dispersion ink, not on the ink concentration. The dispersion medium of AGK101 and the prototype ink is dodecane, and the temperature of the drawing object in this case is preferably 50 degrees or more and 110 degrees or less, and preferably 55 degrees or more and 65 degrees or less.

There are several methods for enabling high-definition drawing even when the temperature of the drawing object is kept constant and inks having different dispersoid concentrations are used. The first is to change the size of the ejection port of the inkjet head. Ink that tends to wet and spread like AGK101 can reduce the amount of ink droplets ejected by using an inkjet head with a small ejection port, and suppress the wetting and spreading. In this embodiment, as described in the second embodiment, an ink jet head having discharge ports with diameters of 50 μm and 34 μm is used. It was confirmed that the landing width can be made smaller by using an inkjet head having an ejection opening with a diameter of 34 μm than when using an inkjet head having an ejection opening with a diameter of 50 μm, for both AGK101 and the prototype ink.

Specifically, as a result of an experiment with the surface temperature of the drawing object set to 58 degrees (setting temperature 65 degrees) and a working distance of 3 mm, when using AGK101, the landing diameter was an average of 135 μm with an orifice of 50 μm and an orifice diameter of 34 μm. The average diameter was 100 μm, and when using prototype ink, the orifice diameter was 50 μm, the landing diameter was 90 μm, the orifice diameter was 34 μm, and the landing diameter was 70 μm on average.

Second is to change the working distance. If the working distance is increased, the time during which the ink is flying increases. In the meantime, the dispersion medium in the flying ink droplets evaporates, and the concentration of the dispersoid in the ink droplets can be increased upon landing. As a specific experiment, when the WD is 3 mm by combining a prototype ink with a surface temperature of 58 degrees (setting temperature 65 degrees), an orifice diameter of 34 μm, the landing diameter is an average of 55 μm, and when WD is 10 mm, the landing diameter is an average of 45 μm. It became.

In addition, it is an effective means to reduce the landing diameter by changing the speed of the ink droplets ejected from the inkjet head, the droplet diameter, etc. by changing the ejection pulse. In a specific operation procedure, all parameters are changed to values that are considered optimal. In other words, by reducing the discharge pulse width and voltage, the droplets discharged from the inkjet head are stabilized, reduced, and speeded up. From the state of the discharged droplets and the pattern to be drawn, the WD and drawing object Fine-tune the surface temperature.

In addition, in order to draw an arbitrary pattern other than drawing a point with a single ink droplet ejected from an inkjet head, it is necessary to land a plurality of ink droplets on a drawing target. At this time, it is necessary that the ink droplets that land on the drawing object overlap each other little by little. Usually, when a high-definition pattern is drawn, it is necessary to overlap the diameter of the ink that has landed on the drawing target by about 0.1 to 0.5 times. As an example of the case where the inventor actually performs the work, when the drawing object is made of glass, the WD is 3 mm, and the temperature of the drawing object is about 60 degrees by using a combination of an inkjet head having an orifice diameter of 34 μm and a prototype ink, If the diameter is 70 μm, the pattern is drawn at a pitch of 60 μm by overlapping each by about 0.14 times n10 μm.

Further, it is more preferable to perform the preliminary discharge described in the above “Mode for Carrying Out the Invention”. If drawing is performed on a heated drawing object without performing preliminary discharge, satellites may be generated in the middle due to the influence of heat from the drawing object, and drawing may be disturbed. In order to prevent this, in this embodiment, after placing the drawing object and the spare substrate on one stage, heating to the same temperature, and performing preliminary discharge on the spare substrate Drawing was performed on the drawing object. In the example implemented by the inventor, the preliminary discharge time is 3 minutes when the drawing object is glass, the WD is 3 mm, and the temperature of the drawing object is 60 ° C., using a combination of an inkjet head having an orifice diameter of 34 μm and a prototype ink. Set to.

This preliminary discharge is performed while observing with the discharge observation mechanism described in the second embodiment. When the ink jet head is placed on the heated spare substrate and the preliminary ejection is started, it is observed that the ejection state changes from 10 seconds at the early stage and from about 10 minutes at the late stage (no change). Many). If the temperature of the drawing object is about 60 degrees, the appearance may change within 1 to 3 minutes. The occurrence of satellites is very common in the change in appearance. In this case, the satellite often disappears when the voltage applied to the ink jet drive unit, V1 shown in FIG. Thus, after observing by the ejection observation mechanism that the ejection of the ink jet has been stabilized by the preliminary ejection, the ink jet head is arranged so as to be on the object to be drawn, and drawing is started.

The above is the embodiment of the pattern drawing method for realizing high-definition drawing of the present invention.

(Embodiment 4)
Next, the pattern drawing method of the present invention for drawing high-definition patterns on various substrates having different surface states using the configuration of the pattern drawing apparatus shown in the second embodiment will be described. The pattern drawing method shown in this embodiment is merely a specific example for carrying out the present invention, and the present invention is not limited only by the contents of the embodiment, and is within the scope conceived by those skilled in the art. It can be changed easily.

In the pattern drawing method of the present invention, as shown in the third embodiment, an ink jet head is placed on a heated drawing object, and an arbitrary pattern is drawn by controlling ink ejection while moving the stage. It is basic to do. In addition, as described in the above “Effects of the Invention”, the material of the drawing object can be selected by using a dispersion ink prepared at a concentration immediately before the viscosity suddenly increases in a high-order function. Arbitrary patterns can be drawn with high definition.

In the experiment, the combination of the inkjet head having an orifice diameter of 34 μm and the prototype ink used in the second and third embodiments was used. The drawing object was glass, a silicon substrate, a solar cell silicon substrate, PET, PEN, polyimide, acrylic, and aluminum. When the temperature of the drawing object was set to 60 ° C., high-definition drawing was possible with glass, silicon substrate, PET, PEN, polyimide, acrylic, and aluminum.

Naturally, the temperature of the drawing object is not the set temperature of the heater built in the stage, but the temperature of the outermost surface of the drawing object. Therefore, the set temperature needs to be slightly changed depending on the thickness of the drawing object. A very thin drawing object such as aluminum, PET, PEN, or polyimide has a set temperature of 65 degrees and a surface temperature of 60 degrees. Thick drawing objects such as acrylic, glass, and silicon substrates had a set temperature of 70 degrees and a surface temperature of 60 degrees. The difference between the set temperature and the actual surface temperature varies depending on the output of the heater used and the experimental environment, so it is considered that such a difference has occurred. In any case, a contact thermometer is used. It is important to manage the surface temperature of the drawing object.

Moreover, among the drawing objects listed above, only the silicon substrate for solar cells could not be finely drawn at a surface temperature of 60 degrees. The same applies to plastics with fine irregularities and scratches on the surface, frosted glass, and the like. As described above, it is understood that when the set temperature is set to 100 degrees and the surface temperature is set to 95 degrees for the silicon substrate for solar cells having unevenness on the surface, wetting spread is suppressed and an arbitrary pattern can be drawn with high definition. It was.

As described above, the tendency for the material having unevenness on the surface to be easily wetted and spread is that an oil-based dispersion medium (in this embodiment, dodecane) having a low surface tension is used as the ink dispersion medium. It is. A liquid having a low surface tension tends to wet and spread, and if there are fine irregularities on the surface of the substrate, it has a function of further enhancing the properties. That is, dodecane ink basically tends to wet and spread, but if the surface has irregularities, it becomes easier to wet and spread. It was found that this wetting and spreading can be solved by increasing the heating temperature of the drawing object.

In the third embodiment, it has been described that the wetting and spreading of the AGK 101 cannot be solved by increasing the heating temperature of the drawing object. This is because a phenomenon such as bumping occurs. However, with respect to the substrate having fine irregularities on the surface, a phenomenon such as bumping did not occur even when the heating temperature was raised, and an arbitrary pattern could be drawn with high definition. This is thought to be due to the fact that the actual surface area is increased due to fine irregularities on the surface, but the principle is unknown.

Of course, also in this embodiment, it is more preferable to perform the preliminary discharge described in the above-mentioned “DETAILED DESCRIPTION OF THE INVENTION”. In the present embodiment, as described in the third embodiment, the drawing object and the spare substrate are placed on one stage, and the two substrates are heated to the same temperature, and then on the spare substrate. The preliminary discharge was performed. Furthermore, during the preliminary discharge, it was confirmed that the discharge of the ink jet was stabilized by the discharge observation mechanism, and then drawing was performed on the drawing target.

The above is the embodiment of the pattern drawing method for realizing high-definition drawing on various substrates according to the present invention.

(Embodiment 5)
In the present embodiment, a pattern drawing method of the present invention for drawing fine wiring having a high aspect ratio will be described using the configuration of the pattern drawing apparatus shown in the second embodiment. The pattern drawing method shown in this embodiment is merely a specific example for carrying out the present invention, and the present invention is not limited only by the contents of the embodiment, and is within the scope conceived by those skilled in the art. It can be changed easily.

Embodiments 1 to 4 of the “DETAILED DESCRIPTION OF THE INVENTION” described the method of drawing an arbitrary pattern with high definition. However, the pattern writing apparatus of the present invention can form fine wiring having a high aspect ratio (the height of the line with respect to the line width) with a slight change in the method of use. Of course, this fine wiring formation can also be applied to various types of substrates without surface treatment of the substrate.

In the present embodiment, the pattern drawing apparatus of the second embodiment is used, and the ink jet heads having the ejection port diameters of 30 μm and 20 μm are used. Also, when drawing the wiring, only one of the plurality of discharge ports that stably discharges ink was used, and control was performed so that ink was not discharged from the other discharge ports. This is because if ink is ejected from all of the plurality of ejection ports, it will interfere with the evaluation of the wiring. In addition, when it is determined that only one ejection port is required for drawing the wiring, an ink jet head having only one ejection port may be used.

As the ink, the prototype ink described in the first to third embodiments is used. This has been explained many times, and is an extremely important factor in forming the high aspect ratio wiring described in this embodiment. As the object to be drawn, a substrate having a flat surface such as glass, silicon, PET, or polyimide was used. As in the fourth embodiment, there was no change in drawing performance due to these base materials.

In the present embodiment, the temperature of the drawing object is heated to 130 ° C. or higher and 150 ° C. or lower. Within this range, high aspect ratio wiring can be formed, and the wiring tends to become slightly thicker as the temperature is lower.

Then, the ejected ink droplets are landed so as to overlap at a distance of 0.5 times or more and 0.8 times or less as compared to the diameter when the ink droplets land on the drawing object. Since the overlapping ratio affects the aspect ratio, particularly the wiring height, the aspect ratio decreases when the ratio is small, and the aspect ratio increases when the ratio is large. However, if the ratio of overlapping inks is increased, the aspect ratio does not continue to increase. If the ink droplets are stacked too much, the ink drying speed cannot keep up, and a line blur called bulge occurs.

Furthermore, the time interval at which the ejected ink droplets overlap, that is, the time interval from the arrival of the nth ink droplet on the drawing object to the arrival of the (n + 1) th ink droplet on the drawing object is 0.1 m. It is necessary that the time is not less than seconds and not more than 10 milliseconds. This is because if it is faster than that, the (n + 1) th ink droplet will land before the nth ink droplet dries, forming a wet spread bulge. On the other hand, if it is slower than that, when the (n + 1) th ink droplet lands, the nth ink droplet is completely dried, and it is impossible to form a wiring with a high aspect ratio. That is, it is considered that when the n + 1th ink droplet lands when the nth ink droplet is in a semi-dry state, these ink droplets have an optimal shape and a high aspect ratio wiring can be drawn. It is done.

As a specific operation, in order to realize an aspect ratio of 0.5, ink droplets were overlapped by 0.7 times the landing diameter, and the landing time interval was set to 0.1 msec. The results are shown in FIGS. 9A and 9B and FIGS. 10A and 10B. 9A and 9B are SEM images when wiring is drawn using an ink jet head having a discharge port diameter of 30 μm. FIG. 9A is a top view and FIG. 9B is a cross-sectional view. 10A and 10B are SEM images when wiring is drawn using an inkjet head having a discharge port diameter of 20 μm. FIG. 10A is a top view and FIG. 10B is a cross-sectional view.

In both results, it can be seen that the wiring having the same thickness as the diameter of the discharge port can be formed, and the height of the wiring is about 0.5 times the width of the wiring. For this reason, when the pattern drawing method of the present embodiment is applied using the pattern drawing apparatus of the present invention, the ink that discharges the landing diameter dcmax from the discharge port while suppressing the wetting spread described in Non-Patent Document 1 above. Can be made substantially the same as the diameter d0 of the wiring, and thus a wiring having the same width as d0 can be formed.

In the present embodiment, an ink in which the solvent is changed from dodecane to tetradecane is also used for the prototype ink. Similarly to the above, when the ink droplets are overlapped by 0.7 times the landing diameter and the landing time interval is 0.1 msec, the temperature of the drawing object is heated to 170 degrees or more and 190 degrees to increase the aspect ratio. A fine wiring with a ratio of 0.5 could be formed. In this example, the diameter of the discharge port of the inkjet head was 30 μm and 20 μm, but the results were not different from those shown in FIGS. 9 and 10. That is, in fine wiring drawing with a high aspect ratio, the properties of the ink dispersion medium greatly affect the set temperature of the drawing object.

Furthermore, in the present embodiment, the same wiring is drawn on two types of glass substrates whose surface tension is greatly changed. One sheet was a normal slide glass, and the other sheet was obtained by dipping the slide glass in an aqueous sodium hydroxide solution for 5 minutes to reduce the surface tension. The wiring drawing conditions were the same as in the above-mentioned dodecane prototype ink, and the same drawing results were obtained for two types of glass.

Moreover, this Embodiment is applicable also to the silicon substrate for solar cells with an uneven surface. In Embodiment 4 described above, it is described that the heating temperature needs to be increased for a substrate with unevenness on the surface. However, when forming a high aspect ratio wiring, the same temperature setting may be used regardless of the unevenness of the surface. I understood.

In this embodiment, only one ejection port of the ink jet head is used. However, when there are a plurality of ejection ports, it is possible to draw a wiring using all of them. When drawing a wiring by ejecting ink from a plurality of ejection openings, it is desirable that the diameter and speed of the ink droplets ejected from all the ejection openings are the same. Otherwise, it is known that wirings having different line widths and aspect ratios are drawn. Therefore, when forming a fine wiring having a high aspect ratio, it is easy to use one ejection port, and in this embodiment, the configuration is shown as an example.

The above is the embodiment of the pattern drawing method for drawing fine wiring having a high aspect ratio using the pattern drawing apparatus of the present invention.

The pattern drawing apparatus and pattern drawing method of the present invention can draw various functional thin films into high-definition patterns on demand without performing any surface treatment on the drawing object. These can be applied to the field of printed electronics. For example, by using a plurality of inks containing functional materials, a thin film transistor, a radio communication antenna, or a radio communication RFID (Radio Frequency IDentification) tag itself Etc. can be produced.

Electronic device products on the market are commercialized after many trial productions. If the functional thin film can be drawn on demand on a high-definition pattern at the prototype stage, the prototype period can be shortened and the product can be delivered quickly.

101 Inkjet Head 102 Stage 103 Controller 104 Reservoir 105 Ink 106 Heater 107 Drawing Object 201 Flat Plate 202 Discharge Port 203 Inkjet Head 204 Ink Supply Port 205 Discharge Port 301 Flexible Substrate 302 Drive Mechanism 401 Preliminary Substrate 501 First Stage 502 Second Stage 601 Ink Drop 602 Drawing Object 603 Center 604 End 605 Landing Width 606 nth Ink Drop 607 n + 1th Ink Drop 608 n−1th Ink Drop

Claims (9)

An inkjet head, a stage, a controller, and a reservoir for storing ink;
The inkjet head has one or more ejection openings for ejecting the ink,
The discharge port is a hole made in a flat plate having an area of 1 cm 2 or more,
The ink is a dispersion ink in which dispersoid particles are dispersed in a dispersion medium,
The ink is filled between the reservoir and the ejection port,
The stage has a heating mechanism for placing the drawing object and heating a drawing scheduled area of the drawing object to a uniform temperature,
The distance between the discharge port of the inkjet head and the drawing object is 0.5 mm to 20 mm,
The pattern drawing apparatus, wherein the controller controls operations of the inkjet head and the stage. In claim 1,
The flat plate is any one of transition metals, Group 13 and Group 14 elements, or alloys thereof, and polyimide, PEN (PolyEthylene Naphthalate), PEEK (PolyEther Ether Ketone),
The pattern drawing apparatus, wherein the discharge port provided in the flat plate has a diameter of 20 μm to 60 μm. In Claim 1 or Claim 2,
The dispersoid particles are non-magnetic metal particles whose surface is coated with a dispersant of 2 nm to 3 nm and whose average particle diameter is 20 nm,
The dispersion medium is a nonpolar chain saturated hydrocarbon,
A pattern drawing apparatus having a dispersoid concentration of 35 to 65 w%. An inkjet head, a stage, a controller, and a reservoir for storing ink;
The inkjet head has one or more ejection openings for ejecting the ink,
The discharge port is a hole made in a flat plate having an area of 1 cm 2 or more,
The ink is a dispersion ink in which dispersoid particles are dispersed in a dispersion medium,
From the reservoir to the ejection port is filled with the ink,
While placing the drawing object on the stage, heating the drawing scheduled area of the drawing object to a uniform temperature,
Arranged so that the inkjet head is on the drawing target area of the drawing object,
The distance between the discharge port and the drawing object is 0.5 mm to 2.0 mm,
The controller controls the state and timing of ink discharged from the discharge port, the relative positions of the inkjet head and the stage, and the heating temperature of the drawing object, and discharges the ink from the discharge port. A characteristic pattern drawing method. In claim 4,
Arrange a pseudo substrate of the same material and the same thickness as the drawing object,
Heating the pseudo substrate to the same temperature as the drawing target area of the drawing object,
After the inkjet head is disposed on the pseudo substrate and ejecting ink for 1 second to 600 seconds,
Arranged so that the inkjet head comes over the drawing target area of the drawing object,
A pattern drawing method, wherein the ink is ejected from the ejection port. In claims 4 to 5,
Compared to the diameter when the ink droplets discharged from the discharge port land on the drawing object,
The (n + 1) th (n> 1) th ink droplet ejected from the ejection port is landed so as to overlap the nth ink droplet ejected from the ejection port at a distance of 0.1 to 0.8 times. A characteristic pattern drawing method. In Claims 4 to 6,
The pattern drawing method, wherein the (n + 1) th ink droplet is landed on the drawing object within a period of 0.1 msec to 10 msec after the nth ink droplet has landed. In claims 4 to 5,
The ink dispersion medium is dodecane,
The dispersoid of the ink is non-magnetic metal particles having a surface coated with a 2 to 3 nm dispersant and an average particle diameter of 20 nm.
The weight concentration of the dispersoid is 35 w% to 65 w%,
Compared to the diameter when the ink droplets discharged from the discharge port land on the drawing object,
The (n + 1) th (n> 1) ink droplet ejected from the ejection port is landed so as to overlap the nth ink droplet ejected from the ejection port at a distance of 0.5 to 0.8 times.
The (n + 1) th ink droplet is landed on the object to be drawn within a period of 2 to 5 milliseconds after the nth ink droplet has landed,
A pattern drawing method, wherein the temperature of the drawing object is 130 to 150 degrees. In claims 4 to 5,
The ink dispersion medium is tetradecane,
The dispersoid of the ink is non-magnetic metal particles having a surface coated with a 2 to 3 nm dispersant and an average particle diameter of 20 nm.
The weight concentration of the dispersoid is 35 w% to 65 w%,
Compared to the diameter when the ink droplets discharged from the discharge port land on the drawing object,
The (n + 1) th (n> 1) ink droplet ejected from the ejection port is landed so as to overlap the nth ink droplet ejected from the ejection port at a distance of 0.5 to 0.8 times.
The (n + 1) th ink droplet is landed on the object to be drawn within a period of 2 to 5 milliseconds after the nth ink droplet has landed,
A pattern drawing method, wherein the temperature of a drawing object is set to 170 degrees to 190 degrees.