JP2012005970A - Method of forming line by inkjet method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a line capable of forming a line having excellent linearity by an inkjet method without using a bank or a mask.SOLUTION: This method of forming a line is used for forming a linear line on a substrate by ejecting two or more droplets of an ink composition from a nozzle by an inkjet method. In the method of forming a line, contact angles θ (°) between a substrate and the droplets and landing diameters D (μm) of the droplets having landed on the substrate are previously obtained, the landing pitches p (μm) of the droplets on the substrate are controlled, and the line is formed so that p/D is included in a region surrounded by three expressions of the following expressions (1) to (3). Expression (1): p/D=0.0045×θ+0.7326, expression (2): p/D=0.0209×θ+0.0672, expression (3): θ=0.

Description

  The present invention relates to a line forming method for forming a straight line by discharging a droplet of an ink composition onto a substrate by an ink jet method.

  The inkjet method using an inkjet printer or the like is not only used as an output means to a conventional paper medium, but also in the formation of each pixel in a color filter, and producing a printed wiring board by discharging conductive ink. The use in the field of electronic devices such as semiconductor devices is also increasing.

  This is due to the fact that the inkjet method is superior in controlling the amount of droplets discharged from the nozzle and the discharge position, and its use is expected to expand in various fields in the future. .

  By the way, there is no problem when droplets are ejected into a predetermined area partitioned by partition walls, as in the case of forming a pixel of a color filter. For example, when a circuit of a printed wiring board is formed. In this case, it is necessary to form a line through a predetermined mask, and it has been difficult to form a circuit or the like by directly discharging droplets onto a substrate. In other words, when droplets are ejected to a region partitioned by a bank such as a partition wall or a mask, the adjacent droplets gather to form a predetermined coating film. In addition, the junction between the droplets does not become a problem. Therefore, for example, as disclosed in Patent Document 1, a method has been proposed in which banks are formed in advance on a substrate and droplets are ejected between the banks to manufacture an electronic device. Further, as in Patent Document 2, a technique for ejecting droplets containing a predetermined resin material onto a substrate having a light-shielding partition is also based on the above-described concept.

  However, if a straight line is formed without using a bank or a mask, the droplets ejected at a predetermined pitch spread out on the substrate and merge with adjacent droplets in a specific direction. It will grow. At that time, if the distance between the droplets becomes too large, unevenness due to the droplets may be formed at a period of one droplet, so-called jaggy. Conversely, if the distance between the droplets becomes too close, the droplets ejected later may be absorbed by the droplets that have landed on the substrate first, and the droplets may concentrate on a specific part, In some cases, so-called bulges, non-uniform wetting and spreading of droplets may be formed. Therefore, in order to avoid such a phenomenon, it has been necessary to form a bank and use a mask when forming a straight line on the substrate. However, forming these in advance not only leads to an increase in cost, but is also undesirable from the viewpoint of shortening the manufacturing process. Therefore, establishment of a technique capable of forming a line directly on a substrate without forming a bank or a mask is desired.

  Therefore, for example, in Patent Document 3, when two or more adjacent droplets are managed as one set, and a plurality of sets are landed on a substrate, the gap between the droplets at the ends of the adjacent sets is determined. A method has been proposed in which a line is formed using a wet spread on a substrate by providing a gap in the substrate. In this way, attempts have been made to reduce the probability of jaggies and bulges by managing droplets in pairs.

JP 2003-317945 A JP 2009-244406 A JP 2009-233612 A

  However, although the method proposed in Patent Document 3 can reduce the occurrence probability of jaggies and bulges, it does not enable line formation while fundamentally eliminating these phenomena. Therefore, in reality, it is necessary to adjust the droplet landing pitch while checking the occurrence of jaggies and bulges by ejecting droplets onto the substrate to form a line, which puts a burden on the work. In addition, there remains a problem in terms of the reproducibility of enabling the formation of a line having good linearity.

  Therefore, the present inventors have repeated trial and error on a technique for forming a line having good linearity while suppressing the occurrence of jaggies and bulges without using a bank or a mask. The relationship between the contact angle of the droplet, the landing diameter of the droplet landed on the substrate, and the landing pitch of the droplet on the substrate on the line shape by three parameters was found, and a relational expression using these parameters was obtained. Based on this, it is possible to predict the shape of the line formed on the substrate in advance, which can greatly improve the work so far and draw lines with good linearity with good reproducibility. Thus, the present invention has been completed.

  Accordingly, an object of the present invention is to provide a line forming method capable of forming a line having good linearity by using an ink jet method without using a bank or a mask.

That is, the present invention is a line forming method in which two or more ink composition droplets are ejected from a nozzle by an ink jet method to form a linear line on a substrate. The angle θ (°) and the landing diameter D (μm) of the droplet landed on the substrate are obtained, and the landing pitch p (μm) of the droplet on the substrate is controlled. A line forming method by an ink jet method, wherein the line is formed so as to be included in a region surrounded by the three formulas (1) to (3).
Formula (1): p / D = 0.0045 × θ + 0.7326
Formula (2): p / D = 0.0209 × θ + 0.0672
Formula (3): θ = 0

  In addition, the present invention provides the ink jet method according to the above, wherein the line is formed after adjusting the contact angle θ (°) by subjecting the surface of the substrate to a liquid repellent treatment or a lyophilic treatment. This is a line forming method.

  According to the line forming method by the ink jet method in the present invention, it becomes possible to predict the line shape formed on the substrate in advance, while suppressing the occurrence of jaggies and bulges without using banks or masks. A line having good linearity can be formed. Therefore, it is possible to save time and effort such as adjusting the landing pitch of droplets and adjusting the landing diameter by controlling the discharge amount of the ink composition after actually forming a line on the substrate. The operation can be greatly improved, and a line having good linearity can be formed with good reproducibility.

FIG. 1 is a graph showing a p / D region necessary for line formation in the present invention. FIG. 2 is a schematic explanatory diagram when the contact angle θ between the substrate and the droplet is calculated by the θ / 2 method. FIG. 3 is a schematic explanatory view showing the relationship between the landing diameter D of the droplets landed on the substrate and the landing pitch p. FIG. 4 is a graph showing the relationship between the contact angle θ and the relational expression p / w. FIG. 5 is a graph showing an example and a comparative example in a graph showing a p / D region necessary for line formation in the present invention.

  First, in the present invention, the ink jet apparatus used for forming a line by the ink jet method is not particularly limited as long as the discharge amount of the ink composition can be adjusted. For example, an ink jet manufactured by Konica Minolta IJ Heads (KM512S [4pL / drop], KM512L [42pL / drop]) are suitable. In addition, it is more preferable to have a high-precision XY stage (resolution 0.5 μm) that can control the discharge position by a linear encoder because the ink jet discharge pitch can be arbitrarily defined.

  In general, an ink jet head of a piezoelectric element, the physical properties of an ink composition in which droplets are stably formed vary depending on the configuration of the head, but the viscosity is 3 mPa · sec to 150 mPa at the temperature inside the head. -It is good that it is sec, Preferably it is 4mPa * sec-30mPa * sec. When the viscosity value is larger than this, it becomes impossible to discharge the droplets. Conversely, when the viscosity value is smaller than this value, the discharge amount of the droplets is not stable. Further, the temperature inside the head varies depending on the stability of the ink composition to be used, but it is desirable to use it at room temperature of 20 ° C to 45 ° C. In particular, in order to increase the solid content in the ink composition and improve the film thickness, a temperature of about 35 to 40 ° C. is generally employed in order to obtain a stable dischargeable viscosity.

In the present invention, when the contact angle θ (°) between the ink composition droplet and the substrate is obtained in advance, it can be calculated by the following method. That is, the contact angle θ is calculated by the θ / 2 method from the wetting spread diameter (landing diameter) D of the droplet after landing on the substrate and the inkjet discharge amount v. This is schematically shown in FIG. For example, the droplet wetting spread diameter D immediately after landing on the substrate is measured by an optical interference type 3D shape observation device or the like, and the ejection amount v (the amount of one droplet ejected from the nozzle) defined by the following equation (4): The droplet height h can be obtained, and the contact angle θ can be obtained from the equation (5).

Hereinafter, the line forming method by the ink jet method of the present invention will be specifically described.
The ink composition is charged into an ink jet head liquid supply bin of an ink jet apparatus, a substrate is set on a drawing stage, and the clearance between the ink jet head ejection surface and the substrate is set to an arbitrary distance of 0.1 to several mm, for example, drawing The Y axis is driven while the X axis of the stage is fixed, and at the same time, a line is drawn with good linearity by discharging droplets at an arbitrary inkjet discharge pitch.

  At this time, in order to set a line drawing condition with good linearity, first, for the purpose of evaluating the wettability between the substrate and the ink composition, as shown in FIG. In a region where the droplet landing pitch (inkjet discharge pitch) p is p / D> 1, that is, a dot is formed with a sufficient distance so that the droplets do not combine with each other. A wetting spread diameter (landing diameter) D is measured by a shape observation device. Then, from the landing diameter D of the droplet that has landed on the substrate and spread wet, and the ejection amount v of one droplet of the droplet ejected from the nozzle of the inkjet head, the above formula (4) ) To obtain the droplet height h, and further to obtain the contact angle θ from the equation (5).

When the contact angle θ has been confirmed, the relational expression p / D between the landing pitch p of the droplets ejected from the nozzles of the inkjet head and the landing diameter D, as shown in FIG. A line drawing with good linearity can be performed by setting so as to be within the region surrounded by the equations (2) and (3). In FIG. 1, in the region where the contact angle θ is low, a wide margin can be taken with respect to the ink jet discharge pitch, but in the region where the contact angle θ is high, the ink jet discharge pitch margin becomes narrow. If the discharge pitch cannot be found in the area surrounded by the formulas (1), (2), and (3), the substrate surface is subjected to a liquid repellent treatment such as deep-UV treatment or a lyophilic solution. The inkjet discharge pitch may be newly set by performing processing and changing the value of the contact angle θ.
Formula (1): p / D = 0.0045 × θ + 0.7326
Formula (2): p / D = 0.0209 × θ + 0.0672
Formula (3): θ = 0

  By the way, the above formulas (1) and (2) are obtained by the inventors confirming and analyzing the limit region of line quality by various experiments. Of these, Equations (1) and (2) indicate the boundaries of “waveform line”, “line with good linearity”, and “bulge” determined according to the criteria for determining whether or not the line is good. This confirmation method is performed by evaluating and confirming the state of the line by drawing the line by changing the landing pitch p on the same substrate for a certain contact angle. In the region formed by the expressions (1) to (3), the region with good linearity is wide in the region where the contact angle is low, and the region with good linearity becomes narrower as the contact angle increases. Show. That is, in the present invention, by setting p / D so as to fall within the region (iii) surrounded by these formulas (1) to (3), it has good linearity without using a bank or a mask. Line can be formed. This region (iii) includes points (points included in the formula) on the respective straight lines of the formulas (1) to (3). When p / D deviates from the region (i) above the formula (1), a wave-shaped line called jaggy is formed. On the other hand, when p / D is out of the region (ii) below the formula (2), the result is that the droplets spread out in a non-uniform manner called a bulge, and a good linear line shape cannot be obtained. Note that in the region of p / D> 1, the lines are not connected correctly, and the droplets ejected from the nozzles of the ink jet apparatus form dots. Further, in the region where θ (1) and (2) cross each other and θ and p / D> 1, the droplets are split and do not form a line.

  In addition, the width w of the line formed by the method of the present invention can be controlled in principle by the droplet discharge amount, the landing pitch, and the contact angle (wetting property). A good line can be formed. The line width w formed by the present invention is preferably 60 μm to 500 μm.

  Further, the relationship between the line width w and the contact angle θ can be obtained experimentally, and it has been found that there is a correlation as shown in FIG. In the region surrounded by the a line and the b line in FIG. 4, a line with good linearity can be formed. That is, an appropriate landing pitch p and contact angle θ for forming a line having a desired line width w can be obtained from FIG. The relationship shown in FIG. 4 is preferably satisfied within the line width condition. The a line and b line forming the boundary region in FIG. 4 can be obtained as follows. In FIG. 1 described above, the wetting and spreading diameter is determined at a certain contact angle, and the landing pitch at the upper and lower limits of the line region having good linearity is determined. From the contact angle and the landing pitch at that time, the maximum value of line width (on line b: minimum value of p) and minimum value (on line a: maximum value of p) are obtained by experiment, and the result is expressed in the form of p / w. This is shown in FIG.

  In the present invention, examples of the composition of the ink composition used for line formation include, for example, resins for imparting properties such as insulation and heat resistance, a solvent for dissolving them, and a colorant added as necessary. It consists of. The resin for imparting characteristics such as insulation and heat resistance may be a resin that is soluble in a solvent described later, but may be a resin that is curable by light or heat. In order to have light or thermosetting properties, light or by introducing a functional group such as an ethylenically unsaturated group such as a (meth) acryl group or a vinyl group, a group having an oxirane ring such as an epoxy group or an oxetane group. It can be thermosetting.

  Moreover, when making it sclerosis | hardenability by light or a heat | fever, the light or the thermal initiator which responds to light or a heat | fever and generate | occur | produces a radical can be added. These can use light or thermal initiators as generally known. Furthermore, as another resin component, for example, a compound having a functional group capable of crosslinking reaction with a resin having a functional group that is cured by light or heat can be added. By adding a compound having a functional group capable of crosslinking, a three-dimensional crosslinked structure is formed by reacting and curing with the resin having the functional group, thereby improving the strength and adhesion of a line formed by inkjet drawing. be able to.

  As the solvent for dissolving the resins, a solvent suitable for the ink jet method can be used. From the viewpoint of preventing the clogging of the ink jet head, the boiling point is preferably 140 ° C. or higher, more preferably 200 ° C. or higher. It is preferable to use a solvent. For the purpose of improving the solubility, a mixed solvent with a low boiling point solvent may be used, but the high boiling point solvent is preferably 50% or more in the solvent component. Moreover, as a coloring agent, well-known things, such as dye and a pigment, can be used. In addition to the purpose of coloring, a filler such as silica may be blended for the purpose of imparting thixotropy to the ink composition.

  The substrate used for line formation is not particularly limited, but preferably has a uniform and smooth surface, and examples thereof include glass, silicon wafers, plastic substrates, etc. Not. Further, as described above, the substrate surface can be subjected to a lyophilic process such as a cleaning process with a volatile solvent such as acetone, a liquid repellent process with a fluorine-based liquid repellent, or a deep-UV process, if necessary.

  Hereinafter, the present invention will be described more specifically based on examples and the like, but the present invention is not limited to these contents. The ink jet devices used in the following examples and comparative examples are as follows.

<Inkjet device>
The inkjet device used in the following example is equipped with a Konica Minolta IJ Piezo-element Driven Inkjet Head (KM512L) capable of ejecting a droplet volume of 42pL / drop, and a highly accurate XY capable of controlling the ejection position with a linear encoder. A stage (resolution 0.5 μm) is provided, and a predetermined inkjet discharge pitch (landing pitch p) can be defined.

<Preparation of ink composition>
Alkaline developing photo-curing resin V-259ME (manufactured by Nippon Steel Chemical Co., Ltd., solid content 56.5%, propylene glycol methyl ether acetate solvent) 200 parts, mixture DPHA of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (Japan) 50 parts by Kayaku Co., Ltd., 25 parts by biphenyl type epoxy resin (YX4000HK by Japan Epoxy Resin), 5 parts by Irgacure 907 (by Ciba Japan), 4,4'-N, N-diethyl-4,4'-diphenyl 0.8 parts of EAB-F (Hodogaya Chemical), 1.9 parts of silane coupling agent S-510 (manufactured by Chisso), 0.5 parts of silicon surfactant BYK325 or BYK330 (manufactured by Big Chemi Japan), and 608 parts of diethylene glycol monoethyl ether acetate Were mixed uniformly. This was filtered through a 0.2 μm microfilter to prepare a test ink composition having a solid content concentration of 22 wt%, a viscosity of 11.3 mPa · sec (23 ° C.), and a density of 1049 kg / m ³ (23 ° C.).

<Board>
The substrate is a 5-inch glass substrate (thickness 0.7 mm) and a Si wafer (thickness 0.7 mm). The glass substrate is cleaned only with acetone (glass substrate 1), followed by a fluorine-based liquid repellent ( αFA-70D6 (manufactured by Daikin Industries) was used to prepare a liquid-repellent treatment (glass substrate 2). In addition, the Si wafer was subjected to deep-UV treatment using a short wavelength ultraviolet irradiation device (manufactured by Oak Manufacturing Co., Ltd., VUM-3073) having a main wavelength of 254 nm. This Deep-UV treatment uses a short-wavelength ultraviolet irradiation device (VUM-3073, manufactured by Oak Manufacturing Co., Ltd.) with a main wavelength of 254 nm (even shorter wavelengths, such as 185 nm) to stain organic components on the substrate surface. Etc. were removed.

<Measurement of contact angle>
The previously prepared ink composition is charged into an ink jet head liquid supply bottle of an ink jet apparatus, a substrate is set on a drawing stage, the clearance between the ink jet head ejection surface and the substrate is 0.5 mm, and the X axis is fixed. Dots are formed by driving the shaft and ejecting droplets at a sufficiently long inkjet ejection pitch (landing pitch) p so that the droplets that have landed on the substrate do not come into contact with each other. The wetting spread diameter (landing diameter) D was measured with an interference type 3D shape observation apparatus. From the wetting spread diameter D and the discharge amount v per droplet, the droplet height h is obtained from the above equation (4) of the contact angle calculation method, and the contact angle θ is obtained from the equation (5). .

<Quality judgment of line shape>
When an intermediate value between the maximum value and the minimum value of the line width in one line is defined as the average value N of the line width, the fluctuation of the line width is within ± 5% of the average value. Time was defined as a line with good linearity.

[Example 1]
Using the prepared ink composition, the wet spread diameter D and the contact angle θ were determined for the glass substrate 2 subjected to the liquid repellent treatment as described above. Next, as shown in FIG. 5, the inkjet discharge pitch p is set to 75 μm so that the p / D is contained in the region iii surrounded by the expressions (1), (2), and (3), and the mask A straight line having a line width w = 69.6 μm was drawn with less. Table 1 shows the line formation conditions according to Example 1.

  The line formed under the above conditions was observed with a stereomicroscope and an optical interference type 3D shape observation apparatus. As a result, bulges and jaggies were not confirmed, and when evaluated according to the above good / bad judgment, the linearity was good. A good line was formed.

  About the board | substrate which formed the line above, after drying the solvent from the ink composition which formed the line on the conditions of 80 degreeC x 3min using a hotplate, further post-baking (oven 230 degreeC x 30min) Curing treatment was performed. As a result, a cured line having good linearity was finally obtained in substantially the same manner as drawn with the ink jet apparatus.

[Examples 2 to 5, Comparative Examples 1 to 3]
In the same manner as in Example 1, the wetting spread diameter D and the contact angle θ were measured and calculated for each substrate, and line drawing was performed under the conditions shown in Table 1, respectively. As shown in FIG. 4, in Examples 2 to 5 where p / D falls within the region iii surrounded by the formulas (1), (2), and (3), good linearity can be obtained. Although confirmed, in Comparative Examples 1 to 3 outside this region iii, a good straight line was not obtained.

  According to the present invention, it is possible to form a line having good linearity without using a bank or a mask. Moreover, according to the present invention, the line shape formed on the substrate can be predicted in advance, so that the work process can be greatly shortened and the yield can be improved. For this reason, the line forming method of the present invention is suitable for forming a line-shaped light-shielding film, etc., as well as for forming a line-shaped insulating film on various devices, and also applicable to forming circuits, wirings, etc. It is.

Claims (2)

A line forming method in which two or more ink composition droplets are ejected from a nozzle by an inkjet method to form a linear line on a substrate,
In advance, the contact angle θ (°) between the substrate and the droplet and the landing diameter D (μm) of the droplet landed on the substrate are obtained.
By controlling the landing pitch p (μm) of droplets on the substrate, the line is formed so that p / D is included in the region surrounded by the following three formulas (1) to (3). A line forming method by an ink jet method.
Formula (1): p / D = 0.0045 × θ + 0.7326
Formula (2): p / D = 0.0209 × θ + 0.0672
Formula (3): θ = 0   The line formation by the ink jet method according to claim 1, wherein the line is formed after the surface of the substrate is subjected to a liquid repellent treatment or a lyophilic treatment to adjust the contact angle θ (°). Method.

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