KR20210048216A - Pattern film for transferring display pixel and method for manufacturing thereof - Google Patents

Abstract

A method for manufacturing a pattern film for display pixel transfer according to an exemplary embodiment of the present application includes the steps of: preparing a master mold having a groove pattern; forming a polydimethylsiloxane-based coating layer and a base layer on the master mold; and removing the master mold. The step of forming the polydimethylsiloxane-based coating layer and the base layer on the master mold is performed in a roll-to-roll process.

Description

Pattern film for display pixel transfer and its manufacturing method {PATTERN FILM FOR TRANSFERRING DISPLAY PIXEL AND METHOD FOR MANUFACTURING THEREOF}

The present application relates to a pattern film for transferring a display pixel and a method of manufacturing the same.

Recently, lighting equipment composed of LED (Light Emitting Diode) has a longer lifespan, relatively low power consumption, and does not emit pollutants in the manufacturing process compared to conventional incandescent or fluorescent lamps, and the demand has exploded. In addition, LEDs are applied not only to display devices using light emission, but also to backlight devices of lighting devices or LCD display devices.

In particular, LEDs can be driven with a relatively low voltage, but have low heat generation and long lifespan due to high energy efficiency. As a technology capable of providing white light with high luminance, which was difficult to implement in the past, has been developed, most of the currently used It is expected to be able to replace the light source device.

Korean Patent Publication No. 10-2015-0033169

The present application is to provide a pattern film for display pixel transfer and a method of manufacturing the same.

An exemplary embodiment of the present application,

Preparing a master mold having a groove pattern;

Forming a polydimethylsiloxane-based coating layer and a base layer on the master mold; And

Including the step of removing the master mold,

The step of forming the polydimethylsiloxane-based coating layer and the base layer on the master mold is performed by a roll-to-roll process, providing a method of manufacturing a pattern film for display pixel transfer.

In addition, another exemplary embodiment of the present application,

It is manufactured according to the above manufacturing method,

Base layer; And a polydimethylsiloxane-based coating layer provided on the substrate layer and including a protrusion pattern on a surface thereof.

In addition, another exemplary embodiment of the present application,

Preparing a pattern film for transferring the display pixels;

Providing a display pixel on the surface of the protruding pattern; And

Transferring the display pixel to an electrode substrate for a display

It provides a method of manufacturing a display comprising a.

According to an exemplary embodiment of the present application, since the protrusion pattern is formed on the surface of the polydimethylsiloxane-based coating layer, the contact surface between the electrode surface and the polydimethylsiloxane-based coating layer can be reduced when transferring the display pixel, and transfer of the display pixel After that, the release property of the polydimethylsiloxane-based coating layer is excellent.

In addition, according to an exemplary embodiment of the present application, in the case of using the display pixel transfer pattern film, only light emitting device chips having a specific interval are selectively contacted among the light emitting device chips formed on the wafer, thereby preventing contamination of the wafer. There are features that can be used.

In addition, according to an exemplary embodiment of the present application, by forming a roll-to-roll process so that the polydimethylsiloxane-based coating layer and the substrate layer are provided in direct contact with each other, conventionally, between the substrate and the polydimethylsiloxane-based film. An adhesive layer (such as a PSA layer) provided in the can be excluded.

In addition, according to the exemplary embodiment of the present application, there is a feature capable of improving dimensional accuracy and stability over time of the display pixel transfer pattern film.

1 is a diagram schematically illustrating a method of manufacturing a pattern film for transferring a display pixel according to an exemplary embodiment of the present application.
2 is a diagram schematically illustrating a pattern film for transferring a display pixel according to a second embodiment, as an exemplary embodiment of the present application.
3 is a diagram schematically illustrating a method of calculating an area ratio occupied by a protruding pattern as an exemplary embodiment of the present application.
4 is a schematic diagram illustrating a pattern film for transferring a display pixel according to an exemplary embodiment of the present application.
5 is a diagram schematically illustrating a pattern film for transferring a display pixel according to Comparative Example 1 of the present application.

Hereinafter, the present application will be described in detail.

Transfer is a series of actions that transfer single or multiple micro LEDs to a counter substrate. As a method of transferring a single chip of an existing LED, it has been applied in the packaging process using Pick & Place equipment, but as the size of the LED is reduced to several microns, a technology to transfer it with high precision is required. To this end, technology has been developed in two ways, direct transfer and print transfer. Direct transfer is a technology that directly bonds a material or thin film to be transferred to a target substrate, and print transfer can be defined as a technique that utilizes an intermediate medium such as electrostatic or bonding stamp. Representative technologies of direct transfer and print transfer are as follows.

The direct transfer method is a method in which p-type GaN is separated into several microns by an etching process and then directly bonded to a substrate on which a fine switching device such as CMOS is formed. If necessary, a silicon or sapphire substrate used as a growth substrate may be removed, and individual GaN devices with a size of several microns separated into a single size may be combined with a switching microelectronic device to facilitate operation current control. This method has the advantage of easy LED manufacturing and transfer, but quality control of each device becomes a very important factor.

It is known that there are two methods of printing type transfer until now. As the first method, Luxvue of the United States proposed a method using an electrostatic head. It is a principle that the contact force with the micro LED is generated by the charging phenomenon by applying a voltage to the head made of silicon material. Although this method has the advantage of being able to selectively transfer a desired area or a single element, there may be a problem of damage to the micro LED due to charging due to a voltage applied to the head during induction of a power outage. The second method, developed by X-Celeprint of the United States, is a method of transferring the LED on the wafer to a desired substrate by applying a transfer head with an elastic polymer material. Compared to the electrostatic head method, there is no problem for damage to the LED, but in the transfer process, the micro LED can be stably transferred when the adhesive force of the elastic transfer head is greater than that of the target substrate, and there is a disadvantage that an additional process for forming an electrode is required. . In addition, maintaining the adhesive force of the elastic polymer material continuously acts as a very important factor.

As the adhesive material for the transfer process, when a conventional master mold and PDMS having excellent replication properties are used, it is very difficult to remove them after transfer to the electrode substrate due to the self-adhesive properties of the surface of the PDMS. In order to accurately transfer a fine pixel pattern for display purposes, a flat plate type face-to-face transfer is inevitable.

In order to solve the above problem, even if a transfer pattern PDMS film to which a specific protrusion pattern shape is added is used, deformation of the protrusion due to pressure during partial transfer may be accumulated depending on equipment precision or thickness uniformity of the pattern film. When unnecessary contact with the bottom PDMS layer occurs due to deformation, it may be difficult to detach the electrode substrate, the detachment speed may be lowered, and the tack time may increase.

When a structure for copying and transferring a specific pattern is formed using PDMS, etc., dimensional distortion may easily occur depending on the lamination method and structure of each layer. When the size of the transfer pattern film is severely distorted, a pixel lighting failure may be caused due to a difference in connection position between the display pixel electrode and the wiring electrode.

Accordingly, in the present application, it is intended to provide a pattern film for display pixel transfer, which can improve dimensional accuracy and stability over time.

A method of manufacturing a pattern film for display pixel transfer according to an exemplary embodiment of the present application includes: preparing a master mold having a groove pattern; Forming a polydimethylsiloxane-based coating layer and a base layer on the master mold; And removing the master mold, wherein the forming of the polydimethylsiloxane-based coating layer and the base layer on the master mold is performed in a roll-to-roll process.

In addition, the display pixel transfer pattern film according to the exemplary embodiment of the present application is manufactured according to the above manufacturing method, and includes a substrate layer; And a polydimethylsiloxane-based coating layer provided on the base layer and including a protrusion pattern on a surface.

In the exemplary embodiment of the present application, the polydimethylsiloxane-based coating layer including a protrusion pattern on the surface may be manufactured from a master mold including a groove pattern corresponding to the protrusion pattern.

Since the polydimethylsiloxane-based coating layer has excellent mold replication and releasability, it can be more effectively applied to the pattern film for display pixel transfer according to the present application. The conventional UV-curable polyurethane-based resin (PUA, Poly Urethane Acrylate), which is mainly used for replication, has a disadvantage in that it is difficult to impart proper hardness and adhesion that affect the transfer characteristics.

Conventionally, due to the self-adhesive property of the surface of the polydimethylsiloxane-based coating layer, it has been very difficult to release the polydimethylsiloxane-based coating layer after transferring a display pixel to a desired electrode substrate. However, in the present application, by forming a protrusion pattern having a specific area ratio and height on the surface of the polydimethylsiloxane-based coating layer, the contact surface between the electrode surface and the polydimethylsiloxane-based coating layer can be reduced when the display pixel is transferred. After transfer, the polydimethylsiloxane-based coating layer has an advantage of excellent release characteristics.

The thickness of the polydimethylsiloxane-based coating layer may range from 100 µm to 500 µm, and may range from 100 µm to 200 µm in consideration of dimensional deformation and the like. When the thickness of the polydimethylsiloxane-based coating layer is less than 100 μm, there is a risk of damage to the micro LED display pixel by impact. In addition, when the thickness of the polydimethylsiloxane-based coating layer exceeds 500 μm, the thickness (height) uniformity and dimensional accuracy of the protrusion pattern may be deteriorated due to deformation of the polydimethylsiloxane-based coating layer having a relatively low hardness.

In the exemplary embodiment of the present application, the polydimethylsiloxane-based coating layer may be a UV-curable polydimethylsiloxane-based coating layer. In the present application, by applying a UV-curable polydimethylsiloxane-based coating layer, it is possible to improve the aging stability of the polydimethylsiloxane-based coating layer compared to conventional room temperature curing. In addition, in the step of forming the polydimethylsiloxane-based coating layer and the base layer on the master mold, the coating process and the curing process of the polydimethylsiloxane-based material can be performed collectively as shown in FIG. Problems such as inflow can be improved.

In the exemplary embodiment of the present application, the display pixel may be a light emitting device chip (LED CHIP). The size of the light emitting device chip may be 10 μm to 100 μm in width and length, respectively, and may be 25 μm to 50 μm.

In the exemplary embodiment of the present application, the substrate layer may be a glass substrate or a transparent plastic substrate having excellent transparency, surface smoothness, ease of handling, and waterproofness, but is not limited thereto, and any transparent substrate commonly used in electronic devices Not limited. Specifically, as the transparent substrate, glass; Polycarbonate resin; Urethane resin; Polyimide resin; Polyester resin; (Meth)acrylate-based polymer resin; It may be made of a polyolefin resin such as polyethylene or polypropylene.

The thickness of the substrate may be 100 μm to 1,000 μm, and may be 300 μm to 700 μm, but is not limited thereto. When the thickness of the substrate is less than 100 μm, dimensional deviation may occur due to tension, and when it exceeds 1,000 μm, the roll-to-roll manufacturing process may not be possible.

In particular, in the exemplary embodiment of the present application, the base layer may be a base layer subjected to a heat treatment process at a temperature of 120°C to 180°C for 10 minutes to 1 hour, and at a temperature of 130°C to 170°C for 20 minutes to It may be a substrate layer subjected to a heat treatment process for 40 minutes. When the substrate layer is a substrate layer subjected to the above-described heat treatment process, heat shrinkage and dimensional deformation can be prevented in the curing process of the polydimethylsiloxane-based coating layer.

In an exemplary embodiment of the present application, based on the entire upper surface of the polydimethylsiloxane-based coating layer, the area ratio occupied by the protrusion pattern may be 5% or less, 1% to 5%, and 1% to 3.5 It can be %. Based on the entire upper surface of the polydimethylsiloxane-based coating layer, if the area ratio occupied by the protrusion pattern exceeds 5%, it may be difficult to detach it from the electrode substrate during the transfer process, and if it is less than 1%, the upper surface of the protrusion On the other hand, a positional alignment defect may occur due to insufficient free space in which the light emitting device chip can be seated in the correct position.

The ratio of the area occupied by the protrusion pattern may be calculated by the following FIG. 3 and Equation 1.

[Equation 1]

The percentage of the area occupied by the protrusion pattern (%) = [(a × b) / Pitch ² ] × 100

In Equation 1,

(a × b) is the upper area of the protrusion, and Pitch is the pitch of the protrusion pattern.

In the exemplary embodiment of the present application, the shape of the protrusion constituting the protrusion pattern may be a polygonal column or a cylindrical shape. In addition, the upper surface of the protrusion may have a flat shape, a convex shape, a concave shape, a combination of these shapes, or the like.

In the exemplary embodiment of the present application, the shape of the protrusion constituting the protrusion pattern is a polygonal column or a cylindrical shape, and the upper surface of the protrusion is a flat shape. More specifically, the shape of the protrusion constituting the protrusion pattern may be a pillar shape such as a square pillar or a cylinder, and the surface of the protrusion has a flat shape to reduce the risk of damage to the light emitting device chip. . In the present application, the "flat shape" shall mean that the surface roughness of 10 points is 0.5 μm or less based on Rz. The Rz can be measured with a Mitutoyo SJ301 measuring device.

The upper area of the protrusion may vary depending on the display resolution and design structure, and more specifically, may be 10 to 20 times the size of the display pixel, but is not limited thereto. In addition, the shape of the protrusion constituting the protrusion pattern may be a square pillar, and in this case, the upper area of the square pillar may be 100 μm × 200 μm, 100 μm × 150 μm, or the like.

In the exemplary embodiment of the present application, the height of the protrusion pattern may be 10 μm to 50 μm. If the height of the protrusion pattern is less than 10 μm, the height difference is not sufficient, so even a very weak transfer pressure causes the deformation of the polydimethylsiloxane-based coating layer to make full contact, and if it exceeds 50 μm, the pattern There is a disadvantage that it becomes difficult to duplicate and supply and demand a master mold.

In addition, the spacing between the protruding patterns, that is, the pitch of the protruding patterns, may be determined by display resolution, and a repetition type of subpixels in consideration of a yield and the like may be included. More specifically, the pitch of the protrusion pattern may be 700 μm to 900 μm, and may be about 800 μm, but is not limited thereto.

The pitch of the protrusion pattern may be arbitrarily changed according to the display resolution, but if the protrusion pitch is less than a certain amount, the contact area during transfer may be relatively increased, which is disadvantageous for detachment. Therefore, in the present application, it is preferable that the pitch of the protrusion pattern for selective transfer of the light emitting device chip is 700 μm to 900 μm. When the pitch of the protrusion pattern is less than 700 μm, there is a disadvantage that it is difficult to apply, such as the size of the pixel (pixel) to be transferred is designed to be too small.

In the exemplary embodiment of the present application, the protrusion pattern is for selectively transferring the LED chip on the wafer by a specific pixel pitch, and by selectively contacting and transferring only specific pixel chips, unnecessary contact , Contamination, etc. can be prevented, and the light emitting device chip can be easily detached.

In the present application, the adhesive force of the surface of the protrusion pattern ^{may be 600 gf/cm 2} or less. The adhesive force of the protruding pattern surface is the maximum load applied when the glass substrate having an area of 1 cm x 1 cm is brought into contact with the protruding pattern surface for 30 seconds under a load of 1,000 gf for 30 seconds and then released. In addition, the adhesive force of the protrusion pattern surface may be ^{300 gf/cm 2 or more.} When the adhesive force of the protrusion pattern surface is ^{less than 300 gf/cm 2} , the light emitting device chip may fall off due to insufficient adhesive force during handling between processes, or unnecessary rotation may occur.

In the present application, the base layer and the polydimethylsiloxane-based coating layer may be provided in direct contact with each other. That is, according to the exemplary embodiment of the present application, since a separate adhesive layer is not provided between the base layer and the polydimethylsiloxane-based coating layer, the manufacturing process can be simplified and pattern dimensional accuracy can be improved.

In the exemplary embodiment of the present application, after forming the polydimethylsiloxane-based coating layer and the base layer on the master mold, the step of forming a cushion layer and a second base layer on the base layer may be further included. I can.

The second base layer may be formed of the same material as the material of the base layer.

The material of the cushion layer is preferably the same as the material of the polydimethylsiloxane-based coating layer, and hardness and thickness may be adjusted for appropriate cushioning performance. The Shore A rubber hardness of the cushion layer may be 20 to 50, and the thickness may be 200 μm to 500 μm.

A pattern film for transferring a display pixel according to an exemplary embodiment of the present application is schematically illustrated in FIGS. 1 and 4 below.

As shown in FIG. 1, a pattern film for display pixel transfer according to an exemplary embodiment of the present application includes: a base layer; And a polydimethylsiloxane-based coating layer provided on the base layer and including a protrusion pattern on a surface. In addition, as shown in FIG. 4 below, the pattern film for display pixel transfer according to an exemplary embodiment of the present application may further include a cushion layer and a second base layer.

In addition, a method of manufacturing a pattern film for transferring a display pixel according to an exemplary embodiment of the present application is schematically illustrated in FIG. 1 below.

In addition, a method of manufacturing a display according to an exemplary embodiment of the present application includes: preparing a pattern film for transferring the display pixels; Providing a display pixel on the surface of the protruding pattern; And transferring the display pixel to an electrode substrate for a display.

The step of providing the display pixel on the surface of the protrusion pattern may be performed by a lift-off technique using a laser, but is not limited thereto.

In the step of transferring the display pixels to an electrode substrate for a display, a method of attaching the display pixels to an electrode substrate to which an adhesive function is imparted by an appropriate transfer pressure may be used.

In addition, according to an exemplary embodiment of the present application, in the case of using the display pixel transfer pattern film, only light emitting device chips having a specific interval are selectively contacted among the light emitting device chips formed on the wafer, thereby preventing contamination of the wafer. There are features that can be used.

Hereinafter, exemplary embodiments described in the present specification are illustrated through examples. However, it is not intended to limit the scope of the embodiments by the following embodiments.

< Example >

< Example 1>

A certain amount of PDMS (Shinetsu, UV curable) was evenly coated on the master mold, and at the same time, a PC (polycarbonate) substrate was laminated without an adhesive (PSA), and the PDMS was cured by irradiation with UV (standard curing condition: 365nm LED lamp. (100 mW/cm ² ), 80 sec). At this time, the prepared PDMS thickness was set to 400 μm, and a polycarbonate having a thickness of 500 μm was used as the substrate.

In addition, the height of the protrusion pattern provided on the surface of the prepared PDMS was 20 μm, the pitch was 800 μm, and the upper area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

< Example 2>

The same was performed as in Example 1, except that the thickness of the PDMS was adjusted to 150 μm and the substrate was used as a PET having a thickness of 250 μm.

The pattern film for display pixel transfer according to the second embodiment is schematically shown in FIG. 2 below.

< Example 3>

It was carried out in the same manner as in Example 2, except that PET used as a substrate was heat-treated (standard heat treatment conditions: 150° C., 30 minutes).

< Comparative example 1>

A certain amount of PDMS (Shinetsu, room temperature curing type) was uniformly coated on the master mold, and after curing it at room temperature (25° C., 24 hours), double-sided pressure sensitive adhesive (PSA) and PC substrate were sequentially laminated. The thicknesses of the PDMS, PSA and PC substrates were prepared at 400 μm, 100 μm and 500 μm, respectively.

In addition, the height of the protrusion pattern provided on the surface of the prepared PDMS was 20 μm, the pitch was 800 μm, and the upper area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

A pattern film for display pixel transfer according to Comparative Example 1 is schematically shown in FIG. 5 below.

< Experimental example >

The dimensional variations of the pattern films for display pixel transfer prepared in Examples 1 to 3 and Comparative Example 1 were measured and shown in Table 1 below. More specifically, the dimensional variation deviation was measured for the dimensional variation deviation compared to the design value for 7 days based on the design value, and the defective rate was evaluated by evaluating the appearance and the presence or absence of foreign matter.

[Table 1]

As described above, according to an exemplary embodiment of the present application, by forming the polydimethylsiloxane-based coating layer and the substrate layer in direct contact with each other by a roll-to-roll process, the conventional substrate and the polydimethylsiloxane An adhesive layer (such as a PSA layer) provided between the acid-based films can be excluded.

In addition, according to the exemplary embodiment of the present application, there is a feature capable of improving dimensional accuracy and stability over time of the display pixel transfer pattern film.

Claims (11)

Preparing a master mold having a groove pattern;
Forming a polydimethylsiloxane-based coating layer and a base layer on the master mold; And
Including the step of removing the master mold,
The step of forming the polydimethylsiloxane-based coating layer and the base layer on the master mold is performed by a roll-to-roll process. The method of claim 1, wherein the polydimethylsiloxane-based coating layer is a UV-curable polydimethylsiloxane-based coating layer. The method according to claim 1, wherein the polydimethylsiloxane-based coating layer comprises a protrusion pattern corresponding to the groove pattern,
The height of the protrusion pattern is 10㎛ to 50㎛ method of manufacturing a pattern film for display pixel transfer. The method of claim 1, wherein the polydimethylsiloxane-based coating layer has a thickness of 100 μm to 500 μm. The method of claim 1, wherein the base layer and the polydimethylsiloxane-based coating layer are provided in direct contact with each other. The method of claim 1, wherein the base layer is a base layer subjected to a heat treatment process at a temperature of 120°C to 180°C for 10 minutes to 1 hour. The method according to claim 1, after the step of forming a polydimethylsiloxane-based coating layer and a base layer on the master mold,
The method of manufacturing a pattern film for display pixel transfer further comprising the step of forming a cushion layer and a second base layer on the base layer. The method of claim 1, wherein the display pixel is a light emitting device chip (LED CHIP). It is prepared according to any one of claims 1 to 8,
Base layer; And a polydimethylsiloxane-based coating layer provided on the base layer and including a protrusion pattern on a surface of the substrate layer. Preparing a pattern film for display pixel transfer of claim 9;
Providing a display pixel on the surface of the protruding pattern; And
Transferring the display pixel to an electrode substrate for a display
A method of manufacturing a display comprising a. The method of claim 10, wherein the display is a transparent light emitting device display.

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