KR20220122165A - LED Laser Repairing System - Google Patents

Abstract

According to an embodiment of the present invention, a mini and micro LED laser repairing system comprises: a laser which is a light source; a mirror transmitting a laser beam emitted from the laser; a Galvano scanner converting a direction of the laser beam and scanning the same on a substrate; an F-θ lens focusing the laser beam with respect to a defective LED chip on the substrate; a vision camera detecting a position of the substrate; and a stage including a work table on which the substrate is disposed and a driving motor which rotates the work table in an X-axis, Y-axis, and a predetermined angle. In addition, a dual laser beam optical unit is provided between the laser and the Galvano scanner to make a laser focus at a lower end of the F-θ lens into two laser beam spots such that the two laser beam spots are formed on each solder of positive and negative electrode pads of the defective LED chip. Therefore, a defect rate for each defective LED chip removal with respect to very small LED chips can be lowered with high accuracy.

Description

LED laser repairing system {LED LASER REPAIRING SYSTEM}

The present invention relates to a mini & micro LED laser repairing system, and more particularly, for very small LED chips of tens of μm to hundreds of μm of mini or micro LED panels, it is possible to reduce the defect rate for each defective LED chip removal with high accuracy. It relates to a mini & micro LED laser repairing system using a dual laser beam optical unit.

An LED laser repair system refers to a system that removes defective chips from a mini LED panel used as a backlight unit of a display panel and a micro LED panel that directly controls RGB color pixels and attaches a new LED chip.

In general, a mini LED of a mini LED panel has a size of several hundred μm or more, and a micro LED of a micro LED panel has a size of 100 μm or less (currently has a size of approximately 50 μm).

Therefore, the LED repair device requires very high work precision because it is necessary to remove and attach a very small LED chip of several tens of μm to several hundreds of μm.

As shown in FIG. 1, LED chips are arranged n x m on a substrate 10, and each LED chip 11 is composed of a pair, usually three can form a pair based on RGB color. , Each LED chip 11 may form a pair of three or more.

There are tens to millions of LED chips 11 on the mini LED panel substrate 10 , and tens of millions of LED chips 11 may be mounted on the micro LED panel substrate 10 .

In general, the LED chip 11 has each of (+) polarity (11a) and (-) polarity (11b) terminals connected to the electrode pad 13 of the substrate. Solder is provided to the electrode pad 13 , and the LED chip 10 and the electrode pad 13 are welded through the solder.

Therefore, in order to remove the LED chip 11 , the electrode pad 13 and the LED chip 11 are separated by irradiating a laser to the solder portion between the electrode pad 13 and the LED chip 11 .

The laser scan field 30 for laser processing increases proportionally with the effective focal length (EFL) of the f-θ lens.

However, as the EFL increases, the laser spot size of the f-θ lens also increases. In general, it is preferable that the laser scanning range 30 is wide, and the size of the laser focal point is preferably small.

When the size of the laser focus is adjusted according to the laser processing conditions and the scanning range is determined accordingly, the single scanning range 30 of the galvanoscanner cannot cover the entire area of the substrate 10, so the worktable is moved to the x, y motor It is possible to move the laser processing area in the substrate 10 by moving the

The movement path P of the worktable constitutes a path so that the laser scanning range can be moved in the shortest distance.

However, when the laser beam is irradiated to the solder portion through the single laser beam scanning 30 , only one electrode pad can be irradiated and the laser beam is not irradiated to the other electrode pad. At this time, even when a laser is irradiated to one electrode pad 13 , heat is conducted through the LED chip 11 , so that the solder of the other electrode pad 13 ′ is also melted.

However, the laser condition in which the LED chip 11 is separated is very sensitive, so the accuracy is lowered and the repetition rate is low, which may increase the defect rate for the removal of the LED chip 11 .

The present invention has been devised to solve this problem, and an object of the present invention is to reduce the defect rate for each defective LED chip removal with high accuracy for very small LED chips of several tens μm to several hundred μm of a mini or micro LED panel. It is to provide an LED laser repairing system using a dual laser beam optical unit that can.

The mini & micro LED laser repairing system according to an embodiment of the present invention includes a laser as a light source, a mirror for transmitting the laser beam emitted from the laser, a galvanoscanner for scanning on a substrate by changing the direction of the laser beam, the An F-θ lens for focusing a laser beam on a defective LED chip on the substrate, a vision camera for detecting the position of the substrate, and an X-axis, Y-axis, and a predetermined angle between the working table on which the substrate is placed and the working table It includes a stage made of a rotating driving motor, and a dual laser beam optical unit that makes the laser focus at the bottom of the F-θ lens become two laser beam spots between the laser and the galvanoscanner, and the two It is characterized in that a laser beam spot is formed on each solder of the positive and negative electrode pads of the defective LED chip.

A mini & micro LED chip repair method according to another aspect of the present invention comprises the steps of moving a laser processing area containing a defective LED chip in a mini & micro LED substrate by moving the x and y motors of the stage, With respect to the processing area, the wavelength of the laser beam is 343 nm and 355 nm of UV wavelength, and the ultra-short pulse control is performed to emit the laser beam. The first and second laser beams are incident on the galvanoscanner at different angles by a mirror, and the two lasers are spaced apart from each other by passing through the F-θ lens from the galvanoscanner. It may include generating a spot, and irradiating two laser spots passing through the F-θ lens to each solder of the negative and positive electrode pads of the defective LED chip.

According to the LED laser repairing system according to an embodiment of the present invention, it is possible to lower the defect rate for removing each defective LED chip with high accuracy for a very small LED chip of several tens of μm to several hundred μm of a mini or micro LED panel.

1 is a diagram illustrating a laser scanning range and a movement gradient of a laser scanning range in a display substrate.
2 is a conceptual diagram of a mini & micro LED laser repairing system according to an embodiment of the present invention.
3A and 3B are diagrams illustrating the configuration of a dual laser beam unit in a mini & micro LED laser repairing system according to an embodiment of the present invention, respectively.
4 is a conceptual diagram illustrating a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention.
5 is a flowchart illustrating a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention.
6 is a graph illustrating a laser and air nozzle on/off method of a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention.
7A and 7B are conceptual views each illustrating a mini & micro LED laser repairing system according to modified embodiments of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail based on the accompanying drawings.

All technical terms used in the present invention, unless otherwise defined, have the following definitions and have the meanings as commonly understood by one of ordinary skill in the art of the present invention. In addition, although preferred methods and samples are described herein, similar or equivalent ones are also included in the scope of the present invention.

Throughout this specification, unless the context requires otherwise, the terms "comprises" and "comprising" include the steps or elements presented, or groups of steps or elements, but include any other step or element, or It is to be understood that a step or group of elements is meant to be implied not to be excluded.

2 to 3b, the mini & micro LED laser repairing system 100 according to an embodiment of the present invention includes a laser 110 as a light source, and a mirror 111 for transmitting the laser beam 110. ), a galvanoscanner 130 for scanning by switching the direction of the laser beam, an F-θ lens 150 for focusing the laser beam, a vision camera 170 for detecting the position of the substrate, and work A table (Working Table; 191 ) and a stage 190 consisting of X-axis, Y-axis, and Z-axis motors 193 and 195 , and a rotation (θ) motor 197 , the laser 110 and the galvanometer scanner 130 . At least one positive electrode pad PAD(+)(11a) in order to separate the LED chip by mounting a double laser beam optical unit 120 between the F-θ lens 150 and making a plurality of laser focal points at the bottom. and at least one negative electrode pad PAD(-)(11b) part at the same time by irradiating a laser to melt the solder 13, so that the LED chip 11 can be divided.

The mini & micro LED laser repairing system 100 according to an embodiment of the present invention controls the air pressure and flow rate of the laser 110 , the galvano scanner 130 , and the air nozzle 210 to be described later. a control unit 200 for the purpose, and an air nozzle 210 that provides a direct force to separate the LED chip 11 by spraying air to the LED chip 11 in which the solder 13 is melted by the laser 110 . ) and a suction unit 230 for sucking the LED chip separated by the air nozzle 210 .

The air nozzle further has an angle adjusting part 211 for adjusting the angle so as to adjust the direct force that separates the LED chip 11 from the substrate 10 , so that the air pressure and flow rate for the LED chip 11 . can be adjusted.

As described above, the solder 13 portion is melted by the laser beam irradiated by the laser 110 , but in order to actually separate the LED chip 11 , air, for example, Clean Dry Air (CDA) ) to separate the LED chip 11 from the substrate 10, and it can be seen that the LED chip 11 completely separated by the suction unit 230 is sucked and treated.

As shown in FIG. 3A , in general, a laser beam output as a DPSS laser in the laser 110 has a polarization characteristic, for example, a linear polarization characteristic of an S polarity or a P polarity.

The dual laser beam optical unit 120 is a device that splits one laser beam into two on the laser light path from the laser 110 and merges them back into two laser beams having a predetermined angle θ, The double laser beam optical unit 120 is a λ/2 phase retarder (Half-Wave Plate: HWP 121) that rotates the linear polarization of the laser beam to be delayed by λ/2 phase when the laser 110 irradiates the laser beam. ) and the linearly polarized light of the laser 110 having a phase difference by λ/2 phase by the λ/2 phase delay unit 121 to the first laser beam (S-polarized light) and the second laser beam (P-) A polarized beam splitter (Polarized Beam Splitter 123) for splitting into polarized light), a transmission mirror 125 for transmitting the second laser beam, and the first and second laser beams when the first and second laser beams are combined This predetermined angle, for example, a laser beam separation angle θ _b , an angle adjustment mirror (Tilt Angle Adjust Mirror 127), and a laser beam combiner that combines the first laser beam and the second laser beam ( Beam Coupler 129) is included.

The laser beam separation angle θ _b has an angle twice as large as the adjustment angle θ _a of the angle control mirror 127 . The laser beam separation angle θ _b between the first and second laser beams Beam 1 and Beam2 must have a very fine angle, and the laser beam separation angle θ _b is the double laser beam unit 120 . ) and the distance between the galvanoscanner 130 varies.

As shown in FIG. 3B , the dual laser beam optical unit 120 includes optical attenuators 124 and 126 on each path after the first and second laser beams Beam 1 and Beam2 are separated. )), so that the laser powers of the first and second laser beams Beam 1 and Beam2 can be matched equally.

In addition, the optical attenuators 124 and 126 may irradiate a laser beam by adjusting the laser power to the positive or negative electrode pads 11a and 11b (PAD(+) or PAD(-)).

As shown in FIG. 4 , the first and second laser beams Beam 1 and Beam2 passing through the dual laser beam optical unit 120 are incident on the galvanoscanner 130 to form two laser beams respectively. The laser spot having power is divided and irradiated by a predetermined interval, and it is known that the predetermined interval corresponds to the distance between the positive or negative electrode pads 11a, 11b (PAD(+) or PAD(-)). can

Now, referring to FIGS. 5 and 6 , a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention will be described in detail.

5 is a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention, and FIG. 6 is a method for repairing an LED chip on a substrate using a mini & micro LED laser repairing system according to an embodiment of the present invention. It is a graph explaining the laser and air nozzle on/off method of the LED chip repair method.

By moving the x and y motors of the stage, it is possible to move the laser processing area containing defective LED chips in the mini & micro LED substrate.

A laser beam is emitted from the laser 10, the wavelength of the laser 110 is a UV wavelength of 343 nm and 355 nm, a pulse type DPSS (Diode Pumped Solid State) laser, the pulse width is ps (pico-second), fs An ultra-short pulse of (femto-second) is used (S10).

The dual laser beam optical unit 120 separates the laser beam so that the two first and second laser beams have a predetermined laser beam separation angle, and the distance between the first and second laser beam spots is adjusted for the angle. The mirror is controlled to correspond to the gap between the positive and negative electrode pads of the defective LED chip (S20)

Since the defective LED chips 10 do not all have the same size, even if the gaps between the positive and negative electrode pads 11a and 11b PAD(+) and PAD(-) are different, correspondingly, the distance between the laser spots is different. Spacing may be adjustable.

The first and second laser beams Beam 1 and Beam2 are incident at different angles from the mirror 113 of the front end of the galvanoscanner 130 ( S30 ), and the x of the galvanoscanner 130 is When the F-θ lens 150 passes through the , y mirrors 131 and 133, two laser spots spaced apart by a predetermined distance may be generated (S40).

The laser beam incident to the galvanoscanner 30 passes through the x and y mirrors 131 and 133 attached to the x and y motor axes inside the galvanoscanner 130 and passes through the f-θ lens 150 . Each solder of the negative and positive electrode pads of the defective LED chip 11 on the substrate 10 is irradiated through (S50)

The galvanoscanner 130 is equipped with x and y mirrors 131 and 133 on the first and second motor shafts 135 and 137), respectively, and limits the angles of the x and y mirrors 131 and 133. By controlling the repeated rotation (+/- 10 degrees), the direction of the laser beam can be changed and sent to a specific position to be processed.

At this time, the vision 70 is not only the position of the substrate, but also the two laser spots are irradiated with a predetermined power according to the distance between the positive and negative electrode pads and the solder for each solder and melted at the same time. This can be performed through the laser beam, and the controller can control the dual laser beam optical unit 120 according to the inspection result of the vision 70 (S55).

In this way, the spacing of the two laser spots is controlled in response to the spacing between the positive and negative electrode pads of the LED chip, and the corresponding spacing between the positive and negative electrode pads of the LED chip and each LED chip. A predetermined output is provided according to the solder of the positive and negative electrode pads of (11) is separated from the substrate 10, and the separated LED chip 10 is sucked through the suction unit 230 (S70).

Then, the working table (WT 191) can move the substrate 10 x, y and rotationally to a position where another target defective LED chip is mounted (S80).

The air nozzle 210 is controlled by the controller 200 to operate according to the irradiation time of the laser 10 in order to remove the LED chip.

When the laser 110 is irradiated while the air is continuously operated from the air nozzle 210, the periphery of the LED chip 11 on the substrate 10 may be polluted, and the reaction of the laser may be reduced by half. .

Accordingly, as shown in FIG. 6 , the controller 200 controls the operation time of the laser 110 and the control timing of the air nozzle 210 , and immediately before the laser 110 is turned off, the air It can be seen that the LED chip 10 is physically controlled by operating the nozzle 210 to supply air from the air nozzle 210 for a predetermined time immediately after the laser 110 is turned off by operating the nozzle 210 .

Referring now to FIGS. 7A and 7B , a description will be given of a mini & micro LED laser repairing system according to modified embodiments of the present invention.

7A and 7B are conceptual views each illustrating a mini & micro LED laser repairing system according to modified embodiments of the present invention.

The mini & micro LED laser repairing system according to modified embodiments of the present invention includes the arrangement of the mini & micro LED laser repairing system and the vision 170 according to the embodiments of the present invention described with reference to FIGS. 1 to 6 . Except for similar bars, the arrangement of the vision 170 will be described in detail below.

As shown in FIG. 7A , the vision 170 may be a vision camera, and like the galvanoscanner 130, it may be attached to the Z-axis.

The vision 170 finds the position of the LED chip 10 in the area of the vision 170 and moves the galvanoscanner 170 to the area of the galvanoscanner 130 for processing.

The deviation between the position of the vision 170 and the position of the galvanoscanner 130 may be corrected by inputting in advance when setting the mini & micro LED laser repairing system according to modified embodiments of the present invention, respectively.

As shown in Fig. 7b, the vision 170 is a built-in vision (BIV) scanner unit that can find the position of the substrate by sharing the F-θ lens with the galvanoscanner together with the laser beam. may be

By adding one more mirror 117 under the vision 170, the size can be reduced mechanically, and when the reflective coating of the mirror 117 is applied, a narrowband dielectric is reflected in the wavelength band used by the vision 170. Stability can be improved by coating (narrow band-dielectric reflection coating).

110: laser 120: dual laser beam optical unit
130: galvanoscanner 150: F-θ lens
170: Vision 190: Stage

Claims (10)

A laser that is a light source, a mirror that transmits the laser beam emitted from the laser, a galvanoscanner that scans on a substrate by switching the direction of the laser beam, and an F-θ lens that focuses the laser beam on a defective LED chip on the substrate , a vision camera for detecting the position of the substrate, and a stage comprising a work table on which the substrate is disposed and a driving motor for rotating the work table in an X-axis, a Y-axis, and a predetermined angle,
A double laser beam optical unit is provided between the laser and the galvanoscanner to focus the laser at the lower end of the F-θ lens into two laser beam spots, so that the two laser beam spots are positive and negative of the defective LED chip. Mini & Micro LED laser repairing system to be formed on each solder of electrode pad. The method of claim 1,
an air nozzle for spraying air to the defective LED chip in which the respective solders are simultaneously melted by the laser beam;
a suction unit for sucking the defective LED chip separated by the air nozzle;
A mini & micro LED laser repairing system comprising a control unit for controlling the operation of the laser, the galvanoscanner, the air nozzle, and the suction unit. 3. The method of claim 2,
The air nozzle includes an angle adjusting unit for adjusting the air injection angle to control the air pressure and flow rate for separating the defective LED chip from the substrate,
The control unit is a mini & micro LED laser repairing system that controls the air nozzle to be operated just before the laser is turned off. The method of claim 1,
The double laser beam optical unit is a λ/2 phase delay by a λ/2 phase delay and the λ/2 phase delay that rotates the linear polarization of the laser beam to be delayed by a λ/2 phase when the laser is irradiated with the laser beam. A polarization beam splitter that separates the linearly polarized light of the laser with a phase difference as much as a first laser beam and a second laser beam, a transmission mirror that transmits the second laser beam, and the first and second laser beams are combined When the first and second laser beams include an angle-adjustable mirror that has a predetermined laser beam separation angle (θ _b ), and a laser beam combiner that combines the first laser beam and the second laser beam,
The laser beam separation angle is controlled according to the distance between the dual laser beam unit and the galvanoscanner mini & micro LED laser repairing system. 5. The method of claim 4,
After the first and second laser beams are separated, an optical attenuator is mounted on each path to control the laser power of the first and second laser beams with respect to the positive and negative electrode pads of the defective LED chip. Laser repairing system. The method of claim 1,
The vision is a mini & micro LED laser repairing system comprising a built-in vision scanner unit that can find the position of the substrate by sharing with the galvanoscanner and the F-θ lens for the laser beam. 7. The method of claim 6,
A mini & micro LED laser further comprising: a splitter that horizontally divides the laser beam with respect to the vision and the galvanoscanner; and a mirror for vertically moving the laser beam irradiated from the splitter to the vision. repairing system. In the mini & micro LED chip repairing method using the mini & micro LED laser repairing system according to any one of claims 1 to 7,
Moving the laser processing area containing the defective LED chip in the mini & micro LED board by moving it with the x and y motors of the stage;
In the laser, the wavelength of the laser beam with respect to the laser processing area is 343 nm, 355 nm UV wavelength, controlling the ultra-short pulse to emit;
separating the laser beam irradiated from the laser into first and second laser beams by a dual laser beam optical unit;
The first and second laser beams are incident at different angles to the galvanoscanner by a mirror;
Generating two laser spots that are spaced apart from each other by passing through the F-θ lens from the galvanoscanner;
and irradiating two laser spots passing through the F-θ lens to each solder of the negative and positive electrode pads of the defective LED chip. 9. The method of claim 8,
Controlling the dual laser beam optical unit by the controller by inspecting whether the two laser beam spots are irradiated to each solder through a vision and whether a predetermined power is irradiated and melted at the same time according to the solder How to repair mini & micro LED chip. 9. The method of claim 8,
When the respective solders of the positive and negative electrode pads of the defective LED chip are melted at the same time, air is supplied from the air nozzle to the defective LED chip to separate the quantity of the LED chip from the substrate;
A mini & micro LED chip repairing method comprising the step of sucking and removing the separated defective LED chip through a suction unit.

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