KR102673659B1 - Apparatus and method for repairing micro LED display - Google Patents

Abstract

The present invention relates to a micro LED display repair device and method. More specifically, it can repair defects in a micro LED display that cannot be repaired with conventional repair devices and can precisely remove defective parts made of various materials. It relates to a micro LED display repair device and method.
The micro LED display repair device of the present invention is a repair device for repairing defects in a micro (ultra-small) LED display, comprising: a stage for holding a micro LED display including a micro LED chip and a circuit pattern for driving the micro LED chip; A laser source that supplies a laser to remove a defective part of the micro LED display, and a laser source that irradiates the laser generated from the laser source by changing the path of the laser to repair the defective part of the micro LED display. An optical module and a control unit that controls the stage, laser source and optical module, wherein the control unit removes a preset first area including the defective area and then removes a second area smaller than the first area. It is characterized by controlling one or more of the stage, laser source, and optical module to do so.

Description

Micro LED display repair device and method {Apparatus and method for repairing micro LED display}

The present invention relates to a repair device and method for repairing a defective micro LED display. More specifically, devices for repairing defects occurring in conventional LCD and OLED displays repair defective areas by cutting or connecting the circuit pattern of the TFT array, but the micro LED display of the present invention is suitable for micro LED displays rather than the conventional method. The present invention relates to a repair device and method for repairing a micro LED display by removing a defective micro LED chip and installing a normally operating micro LED chip.

Recently, flat panel displays such as LCD and OLED, commonly known as FPD (Flat Panel Display), are widely used as displays for TVs and smartphones. However, not only LCD but also OLED have many disadvantages, so research is being actively conducted on displays using micro LED, and micro LED displays with large areas and ultra-high resolution are gradually becoming popular.

There are various shortcomings in the case of LCD and OLED. LCD has limitations in color reproduction, and does not emit light on its own, so it requires a light source such as a backlight, making it difficult to implement in a thin form and difficult to implement in a flexible display. In the case of OLED, it has various advantages such as color reproduction and perfect contrast ratio, but it has a fatal problem called burn-in (afterimage).

Micro LED is a display that can solve all the problems of conventional LCD and OLED and displays images by arranging very small LED chips. Recently, as the size of LED chips can be manufactured very small, it is possible to achieve almost the same resolution as that of LCD and OLED displays. Unlike LCD, self-luminous light is possible, there is no problem such as burn-in of OLED, and the luminance is lower than that of LCD and OLED displays. It is in the spotlight as a next-generation display.

During display manufacturing, defects in which pixels do not turn on or off due to various foreign substances occur. When such defects occur, the entire display must be discarded due to defects, which increases the manufacturing cost. In order to reduce manufacturing costs and defect rates, a repair process to repair defects is essentially included in the manufacturing process.

Conventionally, the defect rate has been lowered through a repair process that repairs defects caused by foreign substances, etc. during the FPD manufacturing process. In the conventional repair process, if the wires included in the FPD are short-circuited, the short-circuited part is cut with a laser, or if the wire is broken, the short-circuited part is cut with a laser. It was performed as a process to connect broken wiring using a metal source and laser.

This conventional repair process was carried out by repairing defects occurring in the TFT array that corresponds 1:1 to the pixel. In addition to these defects, in the case of micro LED displays, the LED chip itself corresponding to the pixel does not operate. There are also defects, and these defects cannot be repaired using conventional repair processes.

In addition, the micro LED display includes not only defective micro LED chips but also various components such as protective films, and is transferred using a first dummy substrate 14, as in the repair method disclosed in Korean Patent Publication No. 10-2021-0070326. /As the peeling process is used, the repair process is complicated, the success rate is low, and the repair tact time is long, leading to low productivity.

The present invention is intended to solve the above problems, and is a micro LED display that can repair defects in a micro LED display that cannot be repaired with conventional repair devices and can precisely remove defective parts made of various materials. To provide a repair device and method.

In order to achieve the above object, the micro LED display repair device of the present invention is a repair device that repairs defects in a micro (ultra-small) LED display, and includes a micro LED chip and a circuit pattern for driving the micro LED chip. A stage for holding an LED display, a laser source for supplying a laser to remove a defective part of the micro LED display, and a laser generated from the laser source to repair the defective part of the micro LED display. It includes an optical module that changes the path of the laser to irradiate, and a control unit that controls the stage, the laser source, and the optical module, wherein the control unit removes the preset first area including the defective area and then removes the first area. It is characterized by controlling one or more of the stage, laser source, and optical module to remove the second area smaller than the area.

In addition, the control unit is characterized in that it adjusts the area of the first area based on the size of the micro LED chip mounted in the defective portion of the micro LED display.

In addition, the area of the first area is characterized by being adjusted based on the shorter length of the horizontal/vertical length of the micro LED chip mounted in the defective area.

In addition, the area of the first area may be adjusted to within twice the shorter of the horizontal/vertical lengths of the micro LED chip.

In addition, the optical module is characterized by including a scanner that changes the laser path to irradiate the laser supplied from the laser source to the defective part of the micro LED display.

In addition, the optical module further includes a cleaning module for cleaning foreign substances remaining after removing defective areas in the micro LED display by irradiating a laser.

In addition, the control unit adjusts the characteristics of the laser, including the wavelength and output of the laser supplied from the laser source, depending on the material in the first area or the second area when removing the laser by irradiating the first area or the second area. It is characterized by:

In addition, in order to achieve the above object, the micro LED display repair method of the present invention is a method of repairing defects in a micro LED display, a micro LED display including a micro LED chip and a circuit pattern for driving the micro LED chip. moving to the stage; The laser supplied from the laser source for removing the defective part of the micro LED display is changed through an optical module and irradiated to the micro LED display to remove the preset first area including the defective part. step; and removing a second area smaller than the first area after removing the first area.

In addition, the step of removing the first area further includes adjusting the area of the first area based on the size of the micro LED chip mounted in the defective area of the micro LED display.

In addition, in the step of adjusting the area of the first area, the area of the first area is adjusted based on the shorter length of the horizontal/vertical length of the micro LED chip mounted in the defective area.

In addition, in the step of adjusting the area of the first area, the area of the first area is adjusted to within twice the shorter of the horizontal/vertical lengths of the micro LED chip.

In addition, the method further includes removing the first area or the second area by irradiating a laser through the optical module and then cleaning remaining foreign substances through a cleaning module.

In addition, when removing the first area or the second area by irradiating the laser through the optical module, the wavelength and output of the laser supplied from the laser source are adjusted depending on the material in the first area or the second area. It is characterized by controlling the characteristics of the laser, including:

The present invention configured as described above has the effect of repairing defects in a micro LED display that cannot be repaired using conventional repair methods.

In addition, in order to repair a defective LED chip, the success rate of repair can be maximized by removing a certain area and then cleaning it.

In addition, by removing the defective part in two steps, the defective part can be removed in a form suitable for mounting a normal micro LED chip, which has the effect of precisely removing defective parts made of various materials.

In addition, by removing the defective part to a state where a normal micro LED chip can be mounted, there is no need to prepare a separate circuit pattern for repair, which has the effect of repairing a high-resolution display.

1 is a perspective view of a micro LED display repair device according to an embodiment of the present invention;
Figure 2 is a diagram showing the process of removing a certain portion using a laser using the micro LED display repair device of the present invention;
Figure 3 is a diagram showing a state in which the first area is removed using the micro LED display repair device of the present invention;
Figure 4 is a diagram showing a state in which the second area is removed through the micro LED display repair device of the present invention;
Figure 5 is a flowchart showing the micro LED display repair method of the present invention.

Hereinafter, the micro LED display repair device and method according to the present invention will be described in detail with reference to the drawings.

Figure 1 is a perspective view of a micro LED display repair device according to an embodiment of the present invention, Figure 2 is a diagram showing the process of removing a certain portion using a laser through the micro LED display repair device of the present invention, and Figure 3 is A diagram showing a state in which the first area has been removed through the micro LED display repair device of the present invention, Figure 4 is a diagram showing a state in which the second region has been removed through the micro LED display repair device of the present invention, and Figure 5 is a diagram showing the state in which the second region has been removed through the micro LED display repair device of the present invention. This is a flowchart showing the micro LED display repair method.

Until recently, LCD and OLED were the representative displays for FPD, but as explained earlier, LCD is not a self-emitting display, so it requires a light source such as a backlight, and due to the limitations of the backlight, a curved display with a certain degree of curvature is possible, but a folder There is a problem that it cannot be applied to flexible displays such as LEDs, and in the case of OLED, self-luminescence is possible, but there is a problem of low durability such as burn-in due to the use of organic light-emitting materials. Because of these problems with FPDs such as conventional LCDs and OLEDs, micro LED displays that are capable of self-emitting and do not have problems such as burn-in are attracting attention.

Conventional FPDs produce defective pixels due to foreign substances during the manufacturing process and essentially include a repair process to ensure that these defective pixels operate normally. In order to solve the problem of pixels not operating normally due to foreign substances during the FPD manufacturing process, the main process is a cutting process to cut off the wiring connecting the circuit pattern when a disconnection occurs due to a foreign substance and when a short circuit occurs. achieve Micro LED displays also have a board with circuit patterns for the operation of the micro LED display. Of course, the conventional repair process can be applied as is to the circuit pattern board of such an LED. However, if a defect occurs in the micro LED chip that makes up the micro LED display, it needs to be repaired. This defect requires repair using a method other than the conventional repair process. The present invention provides a micro LED chip that repairs the defects unique to the micro LED display. This relates to an LED display repair device and method.

The micro LED repair device of the present invention includes a stage 100 for holding the micro LED display at the top to repair defects in the micro LED display with a micro LED chip and a circuit pattern for driving the chip, and a defective portion of the micro LED display. In order to repair, a laser source 200 that supplies a laser, an optical module 300 and a stage 100 that change the path of the laser supplied from the laser source 200 to irradiate the laser to the defective area, a laser source 200, and It includes a control unit 400 that controls the micro LED repair device including an optical module 300.

As described above, the micro LED display is constructed by mounting LED chips on a circuit pattern. After mounting the micro LED chip 20 on the circuit pattern, a protective film 40 is usually formed to protect the display. There are various types of protective films 40, and may be made of a transparent material, but may also be made of an opaque material to prevent light leakage.

In addition, it must have durability to prevent damage to the mounted micro LED chip 20. As an example of the protective film 40, ACF (Anisotropic Conductive Film), which is an anisotropic conductive film that conducts electricity in only one direction, can be used. The main reason for using ACF, an anisotropic conductive film, is to protect the LED chip mounted on the board, but the fine conductive particles in ACF also have the effect of strengthening the connection between the LED chip and the circuit of the board. Of course, the protective film 40 also serves to maintain the micro LED chip 20 mounted on the circuit pattern 30, that is, to securely support the micro LED chip 20.

When removing a certain area of the micro LED display through the optical module 300, it is desirable to process it to a depth that exposes the circuit pattern 30 provided under the protective film 40, such as ACF.

In addition, since the materials of the protective film 40 and the micro LED chip 20 are different, it is necessary to adjust the characteristics of the irradiated laser in order to precisely and accurately remove the defective area, so the defective area is removed in two stages depending on the area to be removed. It is desirable to do so. Through this, a normal micro LED chip (20) can be mounted on the removed area, improving the precision and accuracy of repair. In other words, as the micro LED display 10 becomes more high-resolution and miniaturized, the gap or pitch between LED chips narrows, making it difficult to secure a separate auxiliary circuit pattern. Therefore, the defective micro LED chip 20 must be removed and the corresponding location may be removed. This is because it is advantageous to mount a micro LED chip 20 that operates normally.

The stage 100 of the present invention is configured to hold and fix the micro LED display 10 on the top to perform a repair process of the micro LED display 10. The size of the stage 100 is preferably configured according to the size of the micro LED display 10 to be repaired. It can be configured to use sound pressure to prevent the display from moving during the repair process, or transparent for lighting when lighting is needed at the bottom. Of course, the detailed configuration of the stage 100 can be configured in various ways depending on the repair process environment.

The laser source 200 of the present invention is configured to supply laser to perform a repair process. The laser supplied from the laser source 200 may be a CW laser or a pulsed laser depending on the characteristics of the micro LED display 10 to be repaired. In addition, it is desirable to use an appropriate wavelength range of the laser for the efficiency of the removal process, and the same applies to the output of the laser.

The optical module 300 of the present invention changes the path of the laser supplied from the laser source 200 to irradiate it to an appropriate location to repair defects. The optical module 300 is generally composed of a number of mirrors and lenses. A scanner is used to directly irradiate the laser supplied from the laser source 200 to the micro LED display 10, and an objective lens with an appropriate focal length is used. It can be broadly divided into the methods used. The method using a scanner has the advantage of simplifying the configuration of the optical module 300 and enabling quick path changes by directly irradiating the laser. However, if an image module to photograph the repair process is additionally configured, the laser irradiation process and image acquisition are separate. Because it consists of a configuration, it has the disadvantage of being cumbersome to match the coordinate system and difficult to organically control the repair process. The method of using multiple mirrors and objective lenses has the disadvantage of complicating the configuration, but since the optical system for laser irradiation and the optical system for image taking can be processed in one configuration, laser irradiation and image taking can be performed within one coordinate system. It has the advantage of being able to handle the repair process organically. Any method can be applied to the repair process of a micro LED display, and it is advisable to decide taking into account the environment and characteristics of the repair process.

The optical module 300 removes the part to be repaired by irradiating a laser to the defective micro LED display. As described above, the micro LED chip 20 and the micro LED chip 20 that do not operate normally are placed in the defective area. It is made of various materials, including a protective film 40 to protect the micro LED display 10. Therefore, in order to accurately remove various materials, it is necessary to adjust the characteristics of the laser according to the material. For this purpose, the first area 50 containing the protective film 40 is removed under the control of the control unit 400, and after removing the first area 50, a micro LED chip smaller than the first area 50, for example, is removed. The path of the laser is changed to remove the second area 60, which is equal to or slightly larger than the size of (20). Of course, the characteristics of the laser can be adjusted when removing the first area 50 and the second area 60. By removing the defective part in this two-step manner, there is an advantage that a normally operating micro LED chip 20 can be mounted on the defective part without going through a separate auxiliary line for repair when a defect occurs. In other words, there is an advantage in that a normally operating micro LED chip 20 can be mounted at a defective location, enabling high-quality repair and flexibly performing a repair process in response to various circuit patterns. In addition, when removing the first area 50 and the second area 60, the protective film 40 is removed to a depth D at which the circuit pattern is revealed at the bottom so that a normally operating micro LED chip 20 can be mounted. It is desirable to do so.

After removing the defective part through the optical module 300, a process of mounting a normally operating micro LED chip 20 is required. Through this, the repair process is completed. To this end, to remove foreign substances that may remain on the circuit pattern, A cleaning module (not shown) may be needed to clean foreign substances, and preferably, a mounting module (not shown) for mounting the micro LED chip 20 that operates normally after cleaning is completed is further included to enable repair in one equipment. This is desirable in that the process can be completed in one go.

The cleaning method of the cleaning module can be either using a cleaning liquid or an air blower method that blows cleaning gas. In the case of using a cleaning liquid, the cleaning effect is excellent, but a separate configuration to recover the cleaning liquid must be prepared, and it must be used in a clean room environment. As the repair process is carried out, the cleaning process and post-processing can be very difficult. In the case of the air blow method, the cleaning effect may be lower than the method using cleaning liquid, but the cleaning process is very simple and the configuration of the cleaning module can be simplified. The gas used for cleaning can be selected depending on the composition of the protective film 40 of the micro LED display, and it is preferable to use carbon dioxide to maximize the cleaning effect.

The mounting module is configured to remove the protective film 40 in a certain area through the optical module 300, remove foreign substances on the circuit pattern through the cleaning module, and then perform the process of mounting the LED chip. For mounting an LED chip, it is preferable to use an ink spraying method in which conductive ink such as silver (Ag) is sprayed onto the circuit pattern through a nozzle as an embodiment of the mounting module of the present invention. When using the ink injection method, there is an advantage in that electrical contact between the LED chip and the circuit pattern can be established very simply and a small amount of ink can be accurately sprayed onto the circuit pattern with a very fine width. It is desirable to use an EHD (electrohydrodynamics) ink injection method to properly spray a small amount of ink at the correct location. Of course, the mounting module may include not only a configuration for ink injection, but also a transfer module that accurately positions the normally operating micro LED chip 20 at the location where ink is sprayed.

The control unit 400 of the present invention controls the micro LED repair device of the present invention, including the stage 100, the laser source 200, and the optical module 300. In particular, as described above, the control unit 400 controls the optical module 300 to apply a laser to the first area 50, which occupies most of the protective film 40, in order to accurately and precisely remove various materials constituting the defect area. The laser source 200 and the optical module 300 are controlled to irradiate, remove, and remove the second area 60 containing the micro LED chip 20. The first area 50 and the second area 60 containing the defective area can be adjusted in size to suit the characteristics of the micro LED display 10, including the size of the micro LED chip 20. ), it is desirable to adjust it to within twice the length based on the shorter of the horizontal and vertical lengths. This has the advantage of securing a minimum space for the cleaning process and mounting a normally operating micro LED chip 20 while minimizing the removed part. In addition, as described above, the characteristics of the laser can be adjusted to accurately and precisely remove defects according to various materials through a two-step removal process, and a normally operating micro LED chip (20) is installed in the subsequent process. In order to do this, a removal process can be performed to accurately reveal the circuit pattern, which has the advantage of maximizing the repair success rate.

Hereinafter, the micro LED display repair method of the present invention will be described with reference to FIG. 5, but redundant description will be omitted.

The micro LED display repair method of the present invention moves the micro LED display to repair defects containing the micro LED chip and the circuit pattern for driving the chip to the stage 100, and then repairs the micro LED display 10 through sound pressure, etc. (S100) Change the path of the laser supplied from the laser source 200 to the micro LED display fixed on the stage 100 through the optical module 300 to create the first area 50 of the micro LED display. The corresponding area is removed by irradiating the laser. (S110) After removing the first area 50, the corresponding area is removed by irradiating the laser to the second area 60 through the optical module 300. (S120)

Stage: 100 Laser Source: 200
Optical module: 300 Control unit: 400

Claims (13)

In a repair device that repairs defects in a micro (ultra-small) LED display,
A stage for holding a micro LED display including a micro LED chip and a circuit pattern for driving the micro LED chip,
a laser source that supplies laser to remove defective portions of the micro LED display;
an optical module that irradiates the laser generated from the laser source by changing the path of the laser to repair defective areas of the micro LED display;
Including a control unit that controls the stage, laser source, and optical module,
The control unit controls one or more of a stage, a laser source, and an optical module to remove a preset first area including the defective area and then remove a second area smaller than the first area,
The area of the first area is adjusted based on the size of the micro LED chip mounted on the defective area of the micro LED display, and the area of the first area is determined by the width/length of the micro LED chip mounted on the defective area. It is adjusted within twice the shorter length of the vertical length.
When removing a laser by irradiating a first area or a second area, the characteristics of the laser are adjusted, including the wavelength and output of the laser supplied from the laser source, depending on the material in the first area or the second area. Micro LED display repair device.
delete delete delete In claim 1,
The optical module is a micro LED display repair device characterized in that it includes a scanner that changes the laser path to irradiate the laser supplied from the laser source to the defective part of the micro LED display.
In claim 1,
A micro LED display repair device further comprising a cleaning module for cleaning foreign substances remaining after the optical module removes defective areas within the micro LED display by irradiating a laser.
delete In the method of repairing defects in a micro LED display,
Moving a micro LED display including a micro LED chip and a circuit pattern for driving the micro LED chip to the stage;
changing the path of a laser supplied from a laser source for removing a defective part of the micro LED display through an optical module to remove a preset first area including the defective part;
After removing the first area, it includes removing a second area smaller than the first area,
In the step of removing the first area,
Further comprising adjusting the area of the first area based on the size of the micro LED chip mounted in the defective portion of the micro LED display,
In the step of adjusting the area of the first area,
The area of the first area is adjusted to within twice the shorter length of the horizontal/vertical length of the micro LED chip mounted in the defective area,
When removing the first area or the second area by irradiating the laser through the optical module, the wavelength and output of the laser supplied from the laser source are included depending on the material in the first area or the second area. A micro LED display repair method characterized by adjusting the characteristics of the laser.
delete delete delete In claim 8,
A micro LED display repair method further comprising removing the first or second area by irradiating a laser through the optical module and then cleaning remaining foreign matter through a cleaning module.
delete