KR102166017B1 - Pattern film for transferring display pixel and method for manufacturing display using the same - Google Patents

Abstract

The pattern film for display pixel transfer according to an exemplary embodiment of the present application includes: a substrate; And a polydimethylsiloxane-based film provided on the substrate and including a protrusion pattern on a surface, 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 flat. ), the height of the protrusion pattern is 20 to 50 μm, and the area ratio occupied by the protrusion pattern is 5% or less based on the upper surface of the polydimethylsiloxane-based film.

Description

Pattern film for display pixel transfer and manufacturing method of display using the same {PATTERN FILM FOR TRANSFERRING DISPLAY PIXEL AND METHOD FOR MANUFACTURING DISPLAY USING THE SAME}

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

Recently, luminaires made of LED (Light Emitting Diode) have a longer lifespan than conventional incandescent or fluorescent lamps, consume relatively low power, and have an explosive increase in demand due to the advantages of not emitting pollutants in the manufacturing process. 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 that can provide white light, 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 transfer of display pixels and a method of manufacturing a display using the same.

An exemplary embodiment of the present application,

materials; And

It is provided on the substrate and includes a polydimethylsiloxane-based film including a protrusion pattern on the surface,

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,

The height of the protrusion pattern is 20 to 50 μm,

A display pixel transfer pattern film is provided in which the area ratio occupied by the protrusion pattern is 5% or less based on the upper surface of the polydimethylsiloxane-based film.

In addition, another exemplary embodiment of the present application,

Preparing the display pixel transfer pattern film;

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 film, the contact surface between the electrode surface and the polydimethylsiloxane-based film can be reduced when transferring the display pixel, and transfer of the display pixel After that, the polydimethylsiloxane-based film has excellent release properties.

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.

1 and 2 are diagrams schematically illustrating a pattern film for transferring a display pixel according to 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.

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 in which a material or thin film to be transferred is directly bonded 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, the silicon or sapphire substrate used as the growth substrate may be removed, and individual GaN devices of 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 voltage to the head made of silicon material. This method has the advantage of being able to selectively transfer a desired area or a single element, but 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 failure. 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 only 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 electrode formation is required. . In addition, maintaining the adhesive strength of the elastic polymer material continuously acts as a very important factor.

Accordingly, in the present application, it is intended to provide a transfer pattern film for forming a display pixel having excellent transfer characteristics.

The pattern film for display pixel transfer according to an exemplary embodiment of the present application includes: a substrate; And a polydimethylsiloxane-based film provided on the substrate and including a protrusion pattern on a surface, 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 flat. ), the height of the protrusion pattern is 20 to 50 μm, and the area ratio occupied by the protrusion pattern is 5% or less based on the upper surface of the polydimethylsiloxane-based film.

In 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 to 100 μm in width and length, respectively, and may be 25 to 50 μm.

In the present application, the substrate 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 is not limited. Specifically, as the transparent substrate, glass; Polycarbonate resin; Urethane resin; Polyimide resin; Polyester resin; (Meth)acrylate polymer resin; It may be made of a polyolefin resin such as polyethylene or polypropylene.

The thickness of the substrate may be 100 to 1,000 μm, and may be 300 to 700 μm, but is not limited thereto.

In the present application, based on the upper surface of the polydimethylsiloxane-based film, the area ratio occupied by the protrusion pattern may be 5% or less, 1 to 5%, and 1 to 3.5%. Based on the upper surface of the polydimethylsiloxane-based film, if the area ratio occupied by the protrusion pattern exceeds 5%, it may become difficult to detach from the electrode substrate during the transfer process, and if less than 1%, the upper surface of the protrusion 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 area ratio 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 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 characterized in that it has 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 present application, the height of the protrusion pattern may be 20 to 50 μm. If the height of the protrusion pattern is less than 20 μm, the height level difference is not sufficient, so even a very weak transfer pressure causes the polydimethylsiloxane film to be deformed and is in full contact. 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 the display resolution, and a repetition type of sub-pixels in consideration of a yield and the like may be included. More specifically, the pitch of the protrusion pattern may be 700 to 900 μm, and may be about 800 μm, but is not limited thereto.

The pitch of the protrusion pattern can 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 to 900 μm. If 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 too small.

In 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 polydimethylsiloxane-based film including a protrusion pattern on the surface may be manufactured from a master mold including a groove pattern corresponding to the protrusion pattern. The master mold including the groove pattern may be manufactured using a method known in the art, and more specifically, may be manufactured using a photolithography method, but is not limited thereto.

Since the polydimethylsiloxane-based film has excellent mold reproduction 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 film, it has been very difficult to release the polydimethylsiloxane-based film 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 film, the contact surface between the electrode surface and the polydimethylsiloxane-based film can be reduced when the display pixel is transferred, and After transfer, the polydimethylsiloxane-based film has an advantage of excellent release characteristics.

The thickness of the polydimethylsiloxane-based film may be 200 to 800 μm, and may be 300 to 600 μm in consideration of dimensional change, but is not limited thereto.

In the present application, the adhesive force of the protrusion pattern surface may be 600 gf/cm ² or less. The adhesive force of the protrusion pattern surface is the maximum load applied when the glass substrate having an area of 1 cm × 1 cm is brought into contact with the protrusion 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. If 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 inter-process handling, or unnecessary rotation may occur.

In the present application, an adhesive layer may be additionally included between the substrate and the polydimethylsiloxane-based film.

The adhesive layer may use a material known in the art, more specifically a pressure-sensitive adhesive (PSA), an acrylic adhesive, a synthetic rubber adhesive, etc., but is not limited thereto. In addition, in the exemplary embodiment of the present application, the adhesive layer may use a double-sided PSA, and in this case, one side of the double-sided PSA may include a silicone-based adhesive, and the other side may include an acrylic adhesive, Accordingly, adhesion to different materials may be excellent.

The thickness of the adhesive layer may be 30 to 300 μm, and may be 50 to 150 μm, but is not limited thereto.

A pattern film for transferring a display pixel according to an exemplary embodiment of the present application is schematically illustrated in FIGS. 1 and 2 below.

In addition, a method of manufacturing a display according to an exemplary embodiment of the present application may include 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 the electrode substrate for display, a method of attaching the display pixels to the electrode substrate to which the adhesive function has been 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.

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>

Using a master mold in which a protrusion pattern (20 µm in depth) was formed in an intaglio on a stone table with a flatness of 10 µm or less, polydimethylsiloxane (PDMS, Dow’s mold product) was coated with a gap applicator at a level of about 400 µm at room temperature. Cured for 24 hours. The master mold was fabricated using a photolithography process, etching of silicon or glass, or photoreactive resin.

A silicon-based PSA was covered on the cured PDMS by a coating or laminating method, and a polycarbonate substrate was laminated in that state and gradually duplicated/released from one side to prepare a pattern film for display pixel transfer. The height of the projection pattern of the prepared display pixel transfer pattern film was 20 μm, the pitch was 800 μm, and the top area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

< Example 2>

In Example 1, it was carried out in the same manner as in Example 1, except that the depth of the protrusion pattern formed by engraving the master mold was adjusted to 50 μm. The height of the protrusion pattern of the prepared display pixel transfer pattern film was 50 μm, the pitch was 800 μm, and the top area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

< Comparative example 1>

In Example 1, it was carried out in the same manner as in Example 1, except that the master mold having no protrusion pattern was used.

< Comparative example 2>

In Example 1, it was carried out in the same manner as in Example 1, except that the depth of the protrusion pattern formed by engraving of the master mold was adjusted to 6 μm. The height of the protrusion pattern of the prepared display pixel transfer pattern film was 6 μm, the pitch was 800 μm, and the top area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

< Comparative example 3>

In Example 1, it was carried out in the same manner as in Example 1, except that the depth of the protrusion pattern formed by engraving of the master mold was adjusted to 9 μm. The height of the protrusion pattern of the prepared display pixel transfer pattern film was 9 μm, the pitch was 800 μm, and the top area was (100 μm×200 μm). The area ratio occupied by the protrusion pattern calculated by Equation 1 was 3.1%.

< Experimental example >

The adhesion and transfer evaluation of the films of Examples 1 to 2 and Comparative Examples 1 to 3 were performed, and are shown in Table 1 below.

The following adhesive strength was measured for the maximum load applied when the glass substrate having an area of 1 cm x 1 cm was contacted with a 1,000 gf load for 30 seconds with respect to the protrusion pattern surface, and then released.

The following transcription evaluation was evaluated by the transfer equipment. More specifically, after aligning the positions between the lower electrode substrate and the upper protrusion pattern (w/chip), the transfer process was performed by making contact with each other by pressure. Thereafter, when the upper and lower substrates and the pattern transfer film (100 × 100 mm) were separated (10 μm/sec), the vacuum adsorption state was released and a case in which separation was not possible was judged as a failure.

[Table 1]

As described above, according to the exemplary embodiment of the present application, since the protrusion pattern is formed on the surface of the polydimethylsiloxane-based film, the contact surface between the electrode surface and the polydimethylsiloxane-based film can be reduced when transferring the display pixel, After transfer of the display pixel, the polydimethylsiloxane-based film has excellent release characteristics.

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.

10: description
20: protrusion pattern
30: polydimethylsiloxane-based film
40: adhesive layer

Claims (9)

materials; And
It is provided on the substrate and includes a polydimethylsiloxane-based film including a protrusion pattern on the surface,
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,
The height of the protrusion pattern is 20 to 50 μm,
Based on the upper surface of the polydimethylsiloxane-based film, the ratio of the area occupied by the protrusion pattern is 5% or less,
The area ratio occupied by the protrusion pattern is calculated by Equation 1 below,
The adhesive force of the protrusion pattern surface is 600 gf/cm ² or less for display pixel transfer pattern film:
[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. The pattern film for display pixel transfer according to claim 1, wherein an area ratio occupied by the protrusion pattern is 1 to 3.5% based on an upper surface of the polydimethylsiloxane-based film. delete The pattern film for display pixel transfer according to claim 1, wherein a pitch of the protrusion pattern is 700 to 900 μm. The pattern film of claim 1, wherein the polydimethylsiloxane-based film has a thickness of 200 to 800 μm. The pattern film as set forth in claim 1, wherein the display pixel is a light emitting device chip (LED CHIP). The pattern film for display pixel transfer according to claim 1, further comprising an adhesive layer between the substrate and the polydimethylsiloxane-based film. Preparing a pattern film for display pixel transfer according to any one of claims 1, 2, and 4 to 7;
Providing a display pixel on the surface of the protruding pattern; And
Transferring the display pixel to an electrode substrate for a display
Method of manufacturing a display comprising a. The method of claim 8, wherein the display is a transparent light emitting device display.

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