Register measuring device for printed pattern on flexible substrate

Abstract

The present invention provides a register measuring device for a printed pattern on a flexible substrate, comprising: a sensor configured to face a printed pattern transferred onto a moving flexible substrate to measure the distance to a forward object; and a control unit that synchronizes with the moving speed of the flexible substrate and generates a three-dimensional profile of the printed pattern on the flexible substrate based on distance information measured by the sensor.

Description

Technology Field

[0001] The present invention relates to a register measuring device for a pattern printed on a flexible substrate. Background Technology

[0002] When mass-producing solar cells, secondary batteries, multi-layer ceramic capacitors (MLCC), touchscreen panels (TSP), etc., multiple layers of patterns can be formed sequentially on a substrate, and each layer must have an accurate positional relationship with other adjacent layers.

[0003] Patterns are formed by transferring functional inks and insulating materials onto a flexible substrate through printing processes such as gravure, inkjet, and screen. As high-performance products require miniaturization of line widths and circuit sizes, as well as high integration, positional control at the level of tens of micrometers between printed patterns is essential.

[0004] It is necessary to precisely define the relative positional relationship between layers or patterns, and an indicator of this positional precision is called a register. In other words, a register can be a measure indicating how well printed patterns match their designed positions.

[0005] Conventional register control utilized a register mark formed at a specific location on a substrate. As a specific example, FIG. 1 illustrates a screen printing process for forming a conventional multilayer electrode structure, in which a register mark with a specific pattern can first be imprinted on a substrate using a laser (see FIG. 1(a)). Subsequently, a pattern of the first layer can be printed on the substrate using a screen and a squeegee with functional ink (see FIG. 1(b)). Then, before and after a calendering process (see FIG. 1(d)) to make the printed pattern uniform in thickness and surface condition, and before printing the pattern of the second layer (see FIG. 1(f)), the register mark printed on the substrate is identified using a camera (see FIG. 1(c) and (e)), and the position of the substrate or the pattern printed thereon is aligned.

[0006] This method has limitations in that it cannot measure the actual positions of patterns transferred to the substrate within the printing area, and also, since register control using register marks is limited to two-dimensional position information, it has limitations in determining three-dimensional information such as the thickness or roughness of the printed pattern.

[0007] Recently, especially in the case of secondary batteries, there are limitations to planar positional alignment alone. This is because if the thickness between layers is misaligned, the current path may be distorted or the layers may be damaged, which can lead to product performance degradation as well as accidents such as battery thermal runaway.

[0008] Therefore, in order to improve product quality or mass production yield, there is a growing demand for technologies related to measurement and control of heights, such as the thickness of layers or surface roughness. Prior art literature

[0009] (Patent Document 0001) KR 10-0953475 B1(Patent Document 0002) KR 10-2011-0134822 A(Patent Document 0003) KR 10-1260344 B1 The problem to be solved

[0010] The present invention is intended to provide a register measuring device for a printed pattern on a flexible substrate that can measure three-dimensional information, such as the thickness or roughness of the printed pattern, by directly measuring the flexible substrate and the printed pattern formed thereon using a sensor. means of solving the problem

[0011] To solve the above problem, the present invention provides a register measuring device for a printed pattern on a flexible substrate, comprising: a sensor configured to face a printed pattern transferred onto a moving flexible substrate to measure the distance to a forward object; and a control unit that synchronizes with the moving speed of the flexible substrate and generates a three-dimensional profile of the printed pattern on the flexible substrate based on distance information measured by the sensor.

[0012] According to one embodiment, the sensor may be a laser sensor for measuring distance by irradiating a line laser in the width direction of the moving flexible substrate and using light reflected by the forward object.

[0013] According to one embodiment, the control unit may extract an unprinted portion without the printing pattern from the width-direction profile of the flexible substrate, obtain a first interpolation profile that approximates the extracted portion, and then correct the width-direction profile based on the deviation between the width-direction profile including the printing pattern and the first interpolation profile.

[0014] According to one embodiment, the first interpolation profile may be an n-th degree polynomial curve that approximates the profile for the unprinted portion, and may be a first reference baseline for correcting the width-direction profile.

[0015] According to one embodiment, the control unit may determine that the unprinted portion extracted for obtaining the first interpolation profile is a portion located between the printed patterns on both sides.

[0016] According to one embodiment, the control unit may extract an unprinted portion without the printing pattern from the longitudinal profile of the flexible substrate, obtain a second interpolation profile that approximates the extracted portion, and then correct the longitudinal profile based on the deviation between the longitudinal profile including the printing pattern and the second interpolation profile.

[0017] According to one embodiment, the control unit can perform modeling using the thickness of the corrected printing pattern, with the tension (T) of the flexible substrate, the moving speed (V) of the flexible substrate, and the curing energy (E) for the ink as factors.

[0018] According to one embodiment, the control unit can remove disturbance frequency components originating from the device for moving the flexible substrate when generating the three-dimensional profile. Effects of the invention

[0019] A register measuring device for a printed pattern on a flexible substrate according to one embodiment of the present invention can measure three-dimensional information such as the thickness or roughness of a printed pattern by directly measuring the flexible substrate and the printed pattern formed thereon using a sensor. Brief explanation of the drawing

[0020] Figure 1 is a diagram showing a screen printing process for forming a conventional multilayer electrode structure. FIG. 2 is a configuration diagram of a register measuring device for a printed pattern on a flexible substrate according to one embodiment of the present invention. FIG. 3 is a drawing showing a flexible substrate and a printed pattern measured by a line laser according to one embodiment of the present invention. FIG. 4 is a conceptual diagram of a flexible substrate and a printed pattern according to one embodiment of the present invention. FIG. 5 is a diagram illustrating the process of correcting measurement results for a deformed flexible substrate according to one embodiment of the present invention. FIG. 6 is a diagram showing the thickness and thickness variation of a pattern printed on a flexible substrate according to one embodiment of the present invention. FIG. 7 is a diagram showing the result of implementing a register measuring device according to one embodiment of the present invention. Specific details for implementing the invention

[0021] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols will be assigned the same reference number, and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not inherently possess distinct meanings or roles. Furthermore, in describing embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description will be omitted. Additionally, the attached drawings are intended only to facilitate easy understanding of the embodiments disclosed in this specification; the technical concept disclosed in this specification is not limited by the attached drawings and should be understood to include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0022] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0023] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0024] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0026] FIG. 2 is a configuration diagram of a register measuring device for a printed pattern on a flexible substrate according to one embodiment of the present invention.

[0027] As illustrated in FIG. 2, a register measuring device (100) for a printed pattern on a flexible substrate according to one embodiment of the present invention may include a sensor (10) for measuring the distance to a forward object, which is arranged to face a printed pattern (2) transferred on a moving flexible substrate (1), and a control unit (20) that generates a three-dimensional profile of the printed pattern (2) on the flexible substrate (1) based on distance information measured by the sensor (10), while synchronizing with the moving speed of the flexible substrate (1).

[0028] By using a sensor (10) arranged to face the printed pattern (2) on the flexible substrate (1) in this way, the flexible substrate (1) and the printed pattern (2) can be directly measured, thereby allowing for the measurement of three-dimensional information such as the thickness or roughness of the printed pattern (2).

[0029] We will examine each component in detail below.

[0031] A flexible substrate (1) on which a printed pattern (2) has been transferred to one side can be moved in a predetermined direction at a predetermined speed, and at this time, a sensor (10) is positioned on the flexible substrate (1) at a predetermined distance apart, and can be directed toward the printed pattern (2) transferred to one side of the flexible substrate (1).

[0032] In order to transfer a printing pattern (2) onto a flexible substrate (1), the present invention is not specifically limited, but as a specific example, a roll-to-roll continuous production method may be used. That is, as shown in FIG. 2, a printing pattern (2) can be printed on one side of a flexible substrate (1) using a printing roll (3) for transferring ink onto a flexible substrate (1) and a nip roll (4) for holding the flexible substrate (1) together with the printing roll (3) to transfer ink from the printing roll (3) onto the flexible substrate (1) uniformly.

[0033] A printing roll (3) may have cells (31) formed in a predetermined pattern on its surface engraved thereon, and a chamber doctor (32) provided adjacent to the printing roll (3) may uniformly fill the cells (31) or patterns on the surface of the printing roll (3) with ink. Accordingly, the printing roll (3) receives ink from the chamber doctor (32) on the cells (31) formed in a predetermined pattern on its surface, and then transfers the printing pattern (2) onto the flexible substrate (1) by bringing the cells (31) or patterns into contact with the flexible substrate (1). That is, as the flexible substrate (1) passes through the contact point or area between the printing roll (3) and the nip roll (4), the flexible substrate (1) is stably adhered to the surface of the printing roll (3) by the nip roll (4), so that the ink of the cells (31) on the surface of the printing roll (3) can be uniformly transferred to the flexible substrate (1).

[0034] Meanwhile, the sensor (10) is positioned to face the flexible substrate (1) and / or the printing pattern (2) transferred to one side thereof, which are moved by the rotation of the flexible substrate (1) and / or the printing roll (3), so as to measure depth information (or height information) thereon. To this end, the sensor (10) may be a laser sensor, specifically a line laser sensor, and the line laser irradiated from the sensor (10) may be positioned in the width direction of the flexible substrate (1).

[0035] The sensor (10) may be a line laser sensor capable of irradiating a line laser in the width direction of a moving flexible substrate (1) and measuring the distance between the sensor (10) and the object in front using light reflected by the object in front of the sensor (10).

[0036] Accordingly, the control unit (20) can generate a three-dimensional profile of the flexible substrate (1) and the printed pattern (2) transferred thereon by measuring the distance to the forward object according to a predetermined period using the sensor (10), and at this time, the measurement period using the sensor (10) by the control unit (20) is synchronized with the movement speed of the flexible substrate (1) or the rotation speed of the printing roll (3) and / or the nip roll (4), so that three-dimensional information about the forward object can be measured in conjunction with the movement speed of the flexible substrate (1) or the rotation speed of the printing roll (3) and / or the nip roll (4).

[0037] The results of this are shown in FIG. 3. That is, FIG. 3 is a drawing showing a flexible substrate and a printed pattern measured by a sensor (10) using a line laser according to one embodiment of the present invention.

[0038] Meanwhile, FIG. 4 is a conceptual diagram of a flexible substrate and a printed pattern according to an embodiment of the present invention. As shown in FIG. 4(a), the printed pattern (2) can be arranged in various forms on the flexible substrate (1), and as shown in FIG. 4(b), the printed pattern (2) on the flexible substrate (1) can form a predetermined thickness. Each of the reference numerals 21 to 24 in FIG. 4 may indicate a specific shape of the printed pattern (2) transferred onto the flexible substrate (1).

[0039] In the present specification, as illustrated in FIG. 4, the printed pattern (2) on the flexible substrate (1) may have a predetermined width (w), length, and thickness, and the printed pattern (2) on the flexible substrate (1) may have a register (Rx) in the MD direction, which is the length direction of the flexible substrate (1), a register (Ry) in the CD direction, which is the width direction, and a register (Rz) in the ZD direction, which is the height direction.

[0040] However, among these registers, displacement in the ZD direction, which is the height direction, may occur due to oscillation or wrinkling of the flexible substrate (1). In particular, when printing a printing pattern (2) on the flexible substrate (1) according to a continuous production method such as roll-to-roll, such displacement may continue to occur as the flexible substrate (1) moves, so it may be necessary to correct for such displacement.

[0041] FIG. 5 is a diagram illustrating the process of correcting measurement results for a deformed flexible substrate according to one embodiment of the present invention.

[0042] As illustrated in FIG. 5, a control unit (20) according to one embodiment of the present invention can correct based on the width direction of the flexible substrate (1) and / or correct based on the length direction, which is the movement direction of the flexible substrate (1).

[0043] When the control unit (20) performs width-direction sampling (S1) of the flexible substrate (1) using the sensor (10), a profile such as m1 can be generated. The control unit (20) can extract an unprinted portion of the width-direction profile (m1) that does not have a printed pattern (2) and obtain a first interpolation profile (c1) that approximates the extracted portion.

[0044] Here, the first interpolation profile (c1) may be an n-th degree polynomial curve that approximates the profile for the unprinted portion, and although the present invention is not particularly limited, the n-th degree polynomial curve may be, for example, a second-degree polynomial curve (c1), and by obtaining the coefficients of the polynomial through the least squares method, ax 2 A second-order polynomial curve (c1) of the form +bx+c can be obtained.

[0045] The control unit (20) can use this first interpolation profile (c1) as a first reference baseline and correct the width-direction profile (m1) based on it. That is, when generating the first interpolation profile (c1), the control unit (20) can generate the first interpolation profile (c1) by using at least one of the parts between the two spaced-apart printing patterns (25, 26) as an unprinted part without a printing pattern (2), and then correct the width-direction profile (m1) including the printing pattern (2) using it.

[0046] The control unit (20) can correct the width-direction profile (m1) based on the deviation between the first interpolation profile (c1) and the width-direction profile (m1), and according to a specific embodiment, the control unit (20) can correct the width-direction profile (m1) by subtracting the first interpolation profile (c1) from the width-direction profile (m1) to remove the component of the main curve included in the first interpolation profile (c1).

[0047] It can be seen that the width-direction profile (m1') corrected in this way is formed based on the first interpolation profile (c1') that was flattened, as shown in FIG. 5. As described above, the corrected width-direction profile (m1') may include correction for the printing pattern (2) regarding vibration or wrinkles of the flexible substrate (1), specifically correction for the thickness of the printing pattern (2).

[0048] Meanwhile, the control unit (20) according to one embodiment of the present invention can correct vibrations or wrinkles of the flexible substrate (1) not only for the width direction profile (m1) but also for the length direction profile (m2) of the flexible substrate (1).

[0049] That is, by using the result of sampling (S1) in the width direction of the flexible substrate (1) repeatedly at a predetermined period using the sensor (10), a profile such as m2 can be generated by using any one sampling (S2) arbitrarily selected in the length direction of the flexible substrate (1). The control unit (20) can extract an unprinted portion without a printed pattern (2) from the length direction profile (m2) and obtain a second interpolation profile (c2) that approximates the extracted portion.

[0050] Here, the second interpolation profile (c2) may be an n-th degree polynomial curve that approximates the profile for the unprinted portion, and although the present invention is not particularly limited, the n-th degree polynomial curve may be, for example, a second-degree polynomial curve (c2), and by obtaining the coefficients of the polynomial through the least squares method, ax 2 A second-order polynomial curve (c2) of the form +bx+c can be obtained.

[0051] The control unit (20) can use this second interpolation profile (c2) as a second reference baseline and correct the lengthwise profile (m2) based on it. That is, when generating the second interpolation profile (c2), the control unit (20) can generate the second interpolation profile (c2) by using at least one of the parts between the two spaced-apart printing patterns (27, 28) as an unprinted part without a printing pattern (2), and then correct the widthwise profile (m2) including the printing pattern (2) using this.

[0052] The control unit (20) can correct the longitudinal profile (m2) based on the deviation between the second interpolation profile (c2) and the longitudinal profile (m2), and according to a specific embodiment, the control unit (20) can correct the longitudinal profile (m2) by subtracting the second interpolation profile (c2) from the longitudinal profile (m2) to remove the component of the main curve included in the second interpolation profile (c2).

[0053] It can be seen that the longitudinal profile (m2') corrected in this way is formed based on the second interpolation profile (c2') that is flattened as shown in FIG. 5, and as described above, the corrected longitudinal profile (m2') may include correction for the printing pattern (2) for vibration or wrinkles of the flexible substrate (1), specifically correction for the thickness of the printing pattern (2).

[0054] Meanwhile, a control unit (20) according to one embodiment of the present invention can perform modeling using the thickness of the corrected printing pattern (2) as factors, the tension (T) of the flexible substrate (1), the movement speed (V) of the flexible substrate (1), and the curing energy (E) for the ink of the printing pattern (2).

[0055] FIG. 6 is a drawing showing the thickness and thickness change of a pattern printed on a flexible substrate according to one embodiment of the present invention. As shown in FIG. 6, the printed pattern (2) on the flexible substrate (1) can be formed on the flexible substrate (1) by stacking ink transferred by a plurality of printing rolls (5, 6), thereby forming a plurality of layers (L1, L2) of printed patterns (2).

[0056] Each of the unexplained reference numerals 52 and 62 in FIG. 6 may indicate a chamber doctor for supplying ink to a cell (51, 61) formed on each of the printing rolls (5, 6).

[0057] At this time, when the printing pattern (2) is sequentially transferred to the flexible substrate (1), the height of the printing pattern (2) that is first stacked by the front printing roll (5) may be h1, and the height of the printing pattern (2) that is additionally stacked by the back printing roll (6) thereafter may be h2-h1, and accordingly, the height of the entire printing pattern (2) may be h2.

[0058] A register measuring device (10) according to one embodiment of the present invention can measure the height (or thickness) of a printed pattern (2) on a flexible substrate (1) using a sensor (10) that uses a line laser, and can model the height of the printed pattern (2) using this. Specifically, the control unit (20) can derive a model of the height of the printed pattern (2) on a flexible substrate (1) using the Design of Experiments (DOE) and regression analysis, as shown in Equation 1 below, with the tension (T) of the flexible substrate (1), the moving speed (V) of the flexible substrate (1), and the curing energy (E) of the ink of the printed pattern (2) as factors.

[0059] That is, the control unit (20) can derive the relationship between the factors (T, V, E) and the height of the print pattern (2) by performing regression analysis based on the factors (T, V, E) repeatedly input by the user and the thickness of the print pattern (2) measured by the sensor (10) accordingly.

[0060] [Mathematical Formula 1]

[0061] Rz(x,y) = f(T, V, E)

[0062] Here, T is the tension of the flexible substrate (1), V is the movement speed of the flexible substrate (1), and E can represent the curing energy for the ink of the printed pattern (2).

[0063] At this time, according to a preferred embodiment, the control unit (20) can derive the thickness of a single printed pattern (2) on a flexible substrate (1), as well as the thickness of a printed pattern (2) stacked on a single layer, i.e., the thickness change, as shown in Equation 2 below (see FIG. 6).

[0064] [Mathematical Formula 2]

[0065] h2(x,y) - h1(x,y) = Rz(x,y)

[0066] Here, Rz(x,y) is equal to Equation 1 above.

[0067] Meanwhile, the control unit (20) according to one embodiment of the present invention can remove disturbance frequency components originating from a device for moving a flexible substrate (1), including rolls (3, 4), in addition to the above, when generating a three-dimensional profile corrected in the width direction (or transverse direction) and / or length direction (or longitudinal direction), that is, a three-dimensional profile including a printed pattern (2) corrected in the thickness direction.

[0068] Specifically, the control unit (20) preferably removes periodic or non-periodic noise generated from a device for moving the flexible substrate (1), and to this end, specifically, the disturbance frequency component can be removed using a Fast Fourier Transform (FFT) or a Wavelet Transform.

[0069] Meanwhile, FIG. 7 is a diagram showing the result of implementing a register measuring device according to one embodiment of the present invention.

[0070] A control unit (20) of a register measuring device (100) according to one embodiment of the present invention generates a width-direction profile as shown in FIG. 7(b1) using a sensor (10) for a flexible substrate (1) on which a printed pattern (2) has been transferred, as shown in FIG. 7(a), extracts a portion of the profile to generate a first interpolation profile, and then corrects the width-direction profile using the first interpolation profile as shown in FIG. 7(b2).

[0071] Also, as shown in FIG. 7(b), for a flexible substrate (1) on which a printed pattern (2) has been transferred, a longitudinal profile such as FIG. 7(c1) is generated using a sensor (10), a part of which is extracted to generate a second interpolation profile, and then, as shown in FIG. 7(c2), the longitudinal profile is corrected using the second interpolation profile.

[0072] The result for the height (or thickness) of the printed pattern (2) shown in FIGS. 7(b2) and 7(c2) is 10 to 15 μm, which is similar to the height (or thickness) of the pattern measured by the interferometer, 10 to 17 μm, as shown in FIG. 7(d).

[0074] Preferred embodiments of the present invention have been described in detail above with reference to the drawings. The description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without changing the technical concept or essential features of the present invention.

[0075] Accordingly, the scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning, scope, and equivalent concepts of the claims should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0076] 100: Register measuring device 1: Flexible substrate 2: Print pattern 3, 5, 6: Printing roll 31: Cell 32, 52, 62: Chamber Doctor 4: Niproll 10: Sensor 20: Control unit

Claims

Claim 1 A register measuring device for a printed pattern on a flexible substrate, comprising: a sensor configured to face a printed pattern transferred onto a moving flexible substrate to measure the distance to a forward object; and a control unit that synchronizes with the moving speed of the flexible substrate and generates a three-dimensional profile for the printed pattern on the flexible substrate based on distance information measured by the sensor. Claim 2 A register measuring device for a printed pattern on a flexible substrate, characterized in that, in claim 1, the sensor is a laser sensor for measuring distance by irradiating a line laser in the width direction of the moving flexible substrate and using light reflected by the forward object. Claim 3 A register measuring device for a printed pattern on a flexible substrate according to claim 1, wherein the control unit extracts an unprinted portion without the printed pattern from the width-direction profile of the flexible substrate, obtains a first interpolation profile approximating the extracted portion, and then corrects the width-direction profile based on the deviation between the width-direction profile including the printed pattern and the first interpolation profile. Claim 4 A register measuring device for a printed pattern on a flexible substrate, characterized in that, in claim 3, the first interpolation profile is an n-th degree polynomial curve that approximates the profile for the unprinted portion, and is a first reference baseline for correcting the width-direction profile. Claim 5 A register measuring device for a printed pattern on a flexible substrate, wherein, in claim 3, the control unit is characterized in that the unprinted portion extracted for obtaining the first interpolation profile is a portion located between the printed patterns on both sides. Claim 6 A register measuring device for a printed pattern on a flexible substrate according to claim 1, wherein the control unit extracts an unprinted portion without the printed pattern from the longitudinal profile of the flexible substrate, obtains a second interpolation profile that approximates the extracted portion, and then corrects the longitudinal profile based on the deviation between the longitudinal profile including the printed pattern and the second interpolation profile. Claim 7 A register measuring device for a printed pattern on a flexible substrate, wherein, in any one of claims 3 to 6, the control unit performs modeling using the thickness of the corrected printed pattern as factors for the tension (T) of the flexible substrate, the moving speed (V) of the flexible substrate, and the curing energy (E) for the ink. Claim 8 A register measuring device for a printed pattern on a flexible substrate, wherein, in claim 1, the control unit removes disturbance frequency components originating from a device for moving the flexible substrate when generating the three-dimensional profile.

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