KR20210077126A - Appratus for inspection of micro led package - Google Patents

Abstract

The present invention relates to an inspection device and a method of a micro LED package. The inspection device includes: a stage on which a micro LED package including micro LED units for driving a plurality of active matrix (AM) is loaded; a station provided with a plurality of probes respectively contacting pads of the micro LED unit on the stage; an AM driving driver installed at one side of the station to transmit an electrical signal for driving the micro LED unit to the plurality of probes according to an external control command; and a measuring unit installed under the stage to receive light generated by driving the micro LED unit and measure luminous intensity. Therefore, it is possible to quickly and accurately measure the luminous intensity of each LED unit, such as photoluminescence and electroluminescence.

Description

Inspection apparatus and method of micro LED package {APPRATUS FOR INSPECTION OF MICRO LED PACKAGE}

The present invention relates to an apparatus and method for inspecting a micro LED package capable of performing multi-pixel multi-testing of a micro LED package including micro LED units of an active matrix driving method.

In general, an LED manufactured at a level of 10 ~ 100 um is defined as a micro LED, and a display using a micro LED as a light source is called a micro LED display.

Unlike the existing liquid crystal display (LCD), the micro LED can realize various types of flexible displays because the LED chip expresses red, green, and blue (RGB: Red, Green, Blue) colors without a backlight. It has the advantage of being able to miniaturize, and it is possible to create new functions and convergence new products through integration and flexibility.

1 is a schematic diagram for implementing a display using a general micro LED.

Referring to FIG. 1 , in order to manufacture a micro LED display, techniques such as epitaxial growth, chip development, chip separation, and transfer are required.

Epi-growth is a process of generating a compound semiconductor thin film such as an epitaxial layer and an active layer using MOCVD (Metal Organic Chemical Vapor Deposition) on a sapphire or silicon substrate.

For the manufacture of micro LED chips, design technology that can increase the efficiency when injecting current into the chip, ohmic contact technology that can increase the efficiency of injecting current into a narrow electrode area, and the electrode peeling from the epitaxial layer during the complicated chip manufacturing process Adhesion improvement technology to prevent peeling is required.

The transfer technology is a technology for transferring the micro LED device to the target substrate, and can be divided into direct transfer technology and print transfer technology. Existing LEDs have a size of at least 200 μm and it was easy to pick up the LEDs using a die bonding process and mount them at a desired location. However, it is difficult to mount the micro LED in the conventional method using a vacuum hole (80 μm), and in the case of a display having a high resolution, transfer of more than millions of micro LED chips is required, which greatly increases the process time. There are Pick up Heads method proposed by LuxVue, which is a representative transfer technology, and Elastomer Transfer Printing method proposed by X-Celeprint and UIUC.

In a micro LED display, the micro LED chip itself constitutes a pixel, so a micro LED package with a large amount of micro LEDs is required to implement a high resolution and large display.

In order to control the micro LED package, the LED display mainly uses two driving methods: a passive matrix and an active matrix.

2 is a conceptual diagram of a general passive matrix, and FIG. 3 is a circuit diagram for driving a general active matrix and pixels.

2 and 3 , the passive matrix and the active matrix are basically matrix driven, but the active matrix is more complex than the passive matrix.

The passive matrix cheats through continuous scanning in order to display it once, but the active matrix uses a method of just turning it on. That is, as shown in FIG. 2 , in the passive matrix, modeling is simply like a diode, but in the active matrix, driving using a transistor and a capacitor or a capacitor of a parasitic component is required for a mechanism to turn on the pixel. After selecting a pixel to be turned on using a transistor, a voltage is supplied to accumulate a charge in a capacitor connected to the transistor, so that information is maintained in the previous pixel even when a signal is selecting another pixel.

That is, the ridge matrix driving type micro LED continues to emit light until another signal (next pixel) is input according to the signal of the data line when the scan line is sequentially selected, and includes a driving IC for driving the pixel. .

In such a micro LED package or micro LED module, there may be epi defects, chip process defects, defects in transfer and bonding processes, etc., and these defects cause problems such as dead pixels or defective pixels in the future. . If all of the micro LED packages are transferred without knowing that there is a defect, bad pixels are present in the display. Therefore, micro LED measurement and evaluation are performed using post-chip process equipment such as Prober/Sorter and LED tester to improve product yield by identifying defective chips before LED packaging. For example, the sorter device transmits an electrical signal to the anode and cathode of the micro LED chip and checks the turn-on or turn-off state of the pixel to determine the defective chip.

The MEMS prober transmits signals between the wafer and test equipment to test whether the micro LED chips in the wafer are functioning properly. That is, in order to simultaneously test a plurality of micro LED chips fabricated on a board, a fine probe (probe probe) is fixed on a printed circuit board (PCB), and after contacting it with the pad of the micro LED chip to be tested, the test equipment It receives the electrical signal and transmits it to the micro LED chip to determine the bad chip.

When applied to a micro LED package with 3,000 to 10,000 pixels in the panel, pin-type inspection equipment including sorter equipment and MEMS prober cannot measure performance while driving the driver IC for AM driving, and each Since the micro LED is individually inspected, the inspection speed is slow and the production cost rises. In the MEMS prober, if the size of one chip is 10 µm, the gap between the chips is much smaller than 10 µm, so it is possible to inspect multiple chips at the same time. There is a mechanical limitation in manufacturing the probe structure.

In order to solve the above problems, according to an embodiment of the present invention, a micro LED package including micro LED units of an active matrix driving method is multi-tested for defective/good products for each micro LED unit. There is a purpose.

However, the technical task to be achieved by the present embodiment is not limited to the technical task as described above, and other technical tasks may exist.

As a technical means for achieving the above technical problem, the micro LED package inspection apparatus according to an embodiment of the present invention is loaded with a micro LED package including a plurality of active matrix (AM) driving micro LED units. stage to be; a station in which a plurality of probes respectively contacting the pads of the micro LED unit are installed on an upper portion of the stage; an AM driving driver installed at one side of the station and transmitting an electrical signal for driving the micro LED unit to the plurality of probes according to an external control command; and a measuring unit installed under the stage to receive light generated by driving of the micro LED unit and measure the luminous intensity.

In this case, the station arranges a plurality of probes respectively corresponding to the pads of the plurality of micro LED units to face the micro LED units.

At least one metal material selected from among metal materials including copper (Cu), titanium (Ti), tungsten (W), and gold (Au) is adhered to an end of the probe to a predetermined thickness.

The measuring unit includes: a light receiving sensor array installed to face each of the LED elements of R, G, and B of the micro LED unit to measure the light emitted from each LED element; and a transparent plate installed on the light receiving sensor array so that each of the LED elements and the light receiving sensor array have a predetermined separation distance.

The apparatus may further include inspection equipment for evaluating defective/good products for each pixel by checking whether the luminance measured by the measurement unit is included in a preset normal range.

The test equipment is connected to the AM driving driver through wired communication or wireless communication, and transmits a control command to the AM driving driver so that the RGB characteristics of the micro LED unit are emulated through the AM driving driver.

In addition, the inspection apparatus of the micro LED package according to another embodiment of the present invention, an active matrix (Active Matrix, AM) for driving the micro LED package is loaded stage; a backplane provided with a plurality of probes respectively contacting the pads of the micro LED pixels on an upper portion of the stage; a board on which an AM driving driver is installed on the backplane to transmit electrical signals for driving the micro LED unit to the plurality of probes according to an external control command; and a measuring unit installed under the stage to receive light generated by driving of the micro LED unit and measure the luminous intensity.

The backplane has a via hole for connecting the substrate and the probe, and the backplane has a plurality of probes corresponding to pads of the plurality of micro LED units so as to face the micro LED units.

At least one metal material selected from among metal materials including copper (Cu), titanium (Ti), tungsten (W), and gold (Au) is adhered to an end of the probe to a predetermined thickness.

The apparatus may further include inspection equipment for evaluating defective/good products for each pixel by checking whether the light intensity measured by the measurement unit is included in a preset normal range, wherein the inspection equipment communicates with the AM driving driver by wire communication or wireless communication and transmits a control command to the AM driving driver to emulate the RGB characteristics of the micro LED unit through the AM driving driver.

In a method for inspecting a micro LED package according to an embodiment of the present invention, each LED element of R, G, and B and an active matrix (AM) driving IC are arranged and molded on the upper surface of the substrate, and the lower surface of the substrate forming a micro LED unit in which a pad corresponding to each LED element and a driving IC is positioned; generating a micro LED package by cutting the micro LED unit for each package unit; transmitting an electrical signal for AM driving of the micro LED package in a micro LED unit unit to a pad of each micro LED unit, receiving light generated by the driving of the micro LED unit, and measuring the luminous intensity; deriving location information of the defective micro LED unit by checking whether the measured luminous intensity is within a preset normal range and inspecting defective/good products for each micro LED unit; and transferring and assembling the micro LED unit determined to be a good product excluding the defective micro LED unit based on the location information of the defective micro LED unit.

According to the above-described problem solving means of the present invention, defects of each micro LED unit are automatically inspected in such an AM driving micro LED package to calculate a defective micro LED unit, and then can be utilized in a repair process thereafter.

In addition, the luminous intensity such as photoluminescence and electroluminescence can be quickly and accurately measured for each micro LED unit, and time and cost can be saved through mass inspection.

1 is a schematic diagram for implementing a display using a general micro LED.
2 is a conceptual diagram of a general passive matrix.
3 is a circuit diagram for driving a typical active matrix and pixel.
4 is a view showing the configuration of a micro LED package inspection apparatus according to an embodiment of the present invention.
5 is a plan view illustrating a micro LED package for driving AM according to an embodiment of the present invention.
6 is a bottom view (a), a cross-sectional view (b) and a top view (c) for explaining the AM driving micro LED package according to an embodiment of the present invention.
7 is a view for explaining a normal category for evaluation of the micro LED unit of the inspection equipment according to an embodiment of the present invention.
8 is a view showing the configuration of a micro LED package inspection apparatus according to another embodiment of the present invention.
9 is a flowchart illustrating a method of inspecting a micro LED package according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is "connected" with another part, this includes not only the case of being "directly connected" but also the case of being "electrically connected" with another element interposed therebetween. . Also, when a part "includes" a component, it means that other components may be further included, rather than excluding other components, unless otherwise stated, and one or more other features However, it is to be understood that the existence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded in advance.

The following examples are detailed descriptions to help the understanding of the present invention, and do not limit the scope of the present invention. Accordingly, an invention of the same scope performing the same function as the present invention will also fall within the scope of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a view showing the configuration of a micro LED package inspection apparatus according to an embodiment of the present invention, FIG. 5 is a plan view illustrating the AM driving micro LED package according to an embodiment of the present invention, and FIG. 6 is It is a bottom view (a), a cross-sectional view (b), and a top view (c) for explaining the AM driving micro LED package according to an embodiment of the present invention. 7 is a view for explaining a normal category for evaluation of the micro LED unit of the inspection equipment according to an embodiment of the present invention.

Referring to FIG. 4 , the inspection apparatus of the micro LED package includes, but is not limited to, a stage 110 , a station 120 , an AM driving driver 130 , a measurement unit 140 , and an inspection equipment 150 .

The stage 110 is loaded with a micro LED package 10 generated by cutting a plurality of AM driving micro LED units 11 in package units. At this time, the micro LED unit 11 is molded by disposing each of the LED elements 11c of R, G, and B and an active matrix (AM) driving IC 11d on the upper surface of the package substrate 11a, and the package A pad 11b corresponding to each of the LED elements 11c and the driving IC 11d is positioned on the lower surface of the substrate 11a.

The LED package 100 is generated by cutting these LED units 11 for each package unit. One LED unit 11 constitutes one pixel, or one or more LED units 11 are combined to form one pixel. configurable.

In the station 120 , a plurality of probes 121 contacting the pads of the micro LED unit 11 are installed on the top of the stage 110 . The station 120 arranges a plurality of probes 121 respectively corresponding to the pads of the plurality of micro LED units 11 to face the micro LED units 11 . In this case, one or more metal materials among metal materials including copper (Cu), titanium (Ti), tungsten (W), and gold (Au) are adhered to an end of the probe 121 to a predetermined thickness. Therefore, the probe 121 having a metal material adhered to the tip to a predetermined thickness is provided with rigidity due to the metal material when repeating the inspection process several times while transmitting an electrical signal to the micro LED unit 11 . It can prevent wear and prolong the life of the parts of the probe itself.

The AM driving driver 130 is installed on one side of the station 120, and an electrical signal (ie, an AM driving signal) for driving the micro LED unit 11 to the plurality of probes 121 according to an external control command. to send

The measurement unit 140 is installed under the stage 110 and receives the light of the R, G, and B LED elements 11c generated by the driving of the micro LED unit 11 to measure the luminous intensity. The measurement unit 140 includes a light receiving sensor array 141 for measuring the light emitted by each LED element 11c of R, G, and B, and each LED element 11c and the light receiving sensor array 141 are A transparent plate 142 is installed on the light receiving sensor array 141 to have a predetermined separation distance, and communication interface means (not shown) for transmitting the light intensity measured by the light receiving sensor array 141 to the inspection equipment, etc. includes

The biggest difference between the micro LED unit for AM driving and the micro LED unit for PM driving is the presence or absence of a thin film transistor (TFT) that acts as a switch and a storage capacitor that stores information for a preset period of time (eg, 1 frame). to be.

As shown in FIG. 5, the AM driving micro LED package 10 sequentially supplies electrical signals to the scan lines connected to the scan driving ICs, and the voltage applied to the scan lines serves to turn on the TFT switch, When the switch is turned on, information is put in the selected line through the data line from the data driving IC.

As shown in FIG. 6 , the micro LED package 10 for AM driving is modularized through a packaging process after disposing the micro LED unit 11 on the package substrate 11a and transferring the micro LED unit in units of pixels. At this time, the micro LED unit 11 has at least one red (R), green (G), and blue (B) each LED element 11c on the top surface of the package substrate 11a to form one pixel. , and a driving IC 11d for AM driving of each LED element 11c is located. At this time, each of the LED elements 11c of R, G, and B and the driving IC 11d are molded. In addition, electrodes of data, scan, power, and ground are formed on the lower surface of the package substrate 11a in the form of a pad 11b.

Meanwhile, the inspection equipment 150 evaluates the defective/defective product for each pixel by checking whether the luminance measured by the measuring unit 140 is included in a preset normal range. The test equipment 150 is connected to the AM drive driver 130 by wire communication or wireless communication, and transmits a control command to the AM drive driver 130 to apply an electrical signal to the probe 121 , thereby applying a micro LED for AM driving. The driving IC 11d of the unit 11 is driven to emulate the RGB characteristics of the micro LED unit.

Accordingly, as shown in FIG. 7 , the inspection equipment 150 determines the micro LED unit as a good product when the RGB characteristics (eg, grayscale graph) fall within the normal category, and the RGB characteristics out of the normal range. The micro LED unit with

The inspection equipment 150 may be a wireless communication device with guaranteed portability and mobility, and may be, for example, any type of handheld-based wireless communication device such as a smart phone, a tablet PC, or a notebook computer. In addition, the test equipment may be a wired communication device such as a PC that can be connected to another terminal or server through a network.

8 is a view showing the configuration of a micro LED package inspection apparatus according to another embodiment of the present invention.

Referring to FIG. 8 , in the micro LED package inspection apparatus, the micro package inspection apparatus shown in FIG. 4 , the stage 110 , the AM driving driver 130 , the measurement unit 140 , and the inspection equipment 150 are identically configured. . However, in the micro LED package inspection apparatus according to another embodiment of the present invention, a plurality of probes 221 are installed on the backplane 220 including a plurality of cells corresponding to each of the micro LED units, and a plurality of probes 221 are installed between the cells. A via hole 222 is formed so that the substrate 230 and the probe 221 are connected. In this case, the AM driving driver 130 may be installed on one side of the substrate 230 .

Accordingly, the backplane 220 includes cells for individually driving each of the micro LED units 11 , and a plurality of cells are electrically connected on the backplane 220 .

Since the micro LED package 10 for AM driving is connected to the driving IC 11d for each pixel and driven separately, the micro LED package for AM driving operates with low power, but has a noticeable display brightness loss when viewed from the total lighting time. maintain full brightness without

Such an AM driving micro LED package inspection device automatically inspects the defects of each micro LED unit 11 , calculates a defective pixel, and then utilizes it in a repair process.

Applications of micro LED packages use a large number of micro LED units. Therefore, the inspection device of the micro LED package for AM driving can quickly and accurately measure the luminous intensity of each micro LED unit, such as photoluminescence and electroluminescence, and can save time and money through mass inspection. .

9 is a flowchart illustrating a method of inspecting a micro LED package according to an embodiment of the present invention.

Referring to FIG. 9 , the inspection method of the micro LED package generates a micro LED package by cutting the micro LED unit, which can be performed before the cutting process, but in order to calculate the exact location information of the defective micro LED unit It is preferable to carry out after the cutting process to

First, in the micro LED forming process (S1), each LED element 11c of R, G, and B and an active matrix (AM) driving IC 11d are disposed on the upper surface of the package substrate 11a and molded, A micro LED unit 11 in which a pad 11b corresponding to each LED element 11c and a driving IC 11d is positioned is formed on the lower surface of the package substrate 11a.

In the micro LED package creation process (S2), the micro LED unit 11 is cut for each package unit to make a micro LED package.

The inspection process (S3) transmits an electrical signal for AM driving of the micro LED package 10 to the micro LED unit 11 to the pad of each micro LED unit 11, so that the LED element 11c of the micro LED unit 11 is It receives the light generated by driving and measures the luminous intensity.

In the defect detection process (S4), it is checked whether the measured luminous intensity is within a predetermined normal range, and the defective/defective product is inspected for each micro LED unit to derive location information of the defective micro LED unit. As shown in FIG. 5 , in the micro LED package, the location information of the defective micro LED unit has the horizontal axis as the X axis and the vertical axis as the Y axis, and (x, y) of the defective micro LED unit is the location information.

The transfer and assembly process (S5) transfers and assembles the micro LED units determined to be good products except for the defective micro LED units based on the location information of the defective micro LED units.

The inspection method of the micro LED package according to the embodiment of the present invention described above may also be implemented in the form of a recording medium including instructions executable by a computer, such as a program module executed by a computer. Such recording media includes computer-readable media, and computer-readable media can be any available media that can be accessed by a computer, and includes both volatile and nonvolatile media, removable and non-removable media. Computer readable media also includes computer storage media, which include volatile and nonvolatile embodied in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. , both removable and non-removable media.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

10: Micro LED package
11: Micro LED unit
110: stage
120: station
121, 221: probe
130: AM drive driver
140: measuring unit
150: inspection equipment
220: backplane
222: via hole
230: substrate

Claims (14)

a stage on which a micro LED package generated by cutting a plurality of active matrix (AM) driving micro LED units for each package unit is loaded;
a station installed on the stage and provided with a plurality of probes respectively contacting the pads of the micro LED unit;
an AM driving driver installed at one side of the station and transmitting an electrical signal for driving the micro LED unit to the plurality of probes according to an external control command; and
Inspection apparatus of a micro LED package, including a measuring unit installed under the stage to receive light generated by driving of the micro LED unit and measure the luminous intensity. The method of claim 1,
In the station, a plurality of probes corresponding to the pads of the plurality of micro LED units are disposed to face each micro LED unit, the micro LED package inspection apparatus. The method of claim 1,
Inspection apparatus of a micro LED package, wherein one or more metal materials among metal materials including copper (Cu), titanium (Ti), tungsten (W), and gold (Au) are adhered to the tip of the probe to a predetermined thickness . The method of claim 1,
The measuring unit is
a light receiving sensor array installed to face each of the LED elements of R, G, and B of the micro LED unit to measure light emitted from each LED element; and
The inspection device of the micro LED package, including a transparent plate installed on the light receiving sensor array so that each of the LED elements and the light receiving sensor array has a predetermined separation distance. The method of claim 1,
The inspection apparatus of the micro LED package, which further includes inspection equipment for evaluating defective/good products for each pixel by checking whether the luminous intensity measured by the measurement unit is included in a preset normal range. The method of claim 1,
The test equipment is connected to the AM drive driver through wired communication or wireless communication, and transmits a control command to the AM drive driver so that the RGB characteristics of the micro LED unit are emulated through the AM drive driver, micro LED package 's inspection device. a stage on which a micro LED package generated by cutting a plurality of active matrix (AM) driving micro LED units for each package unit is loaded;
a backplane provided with a plurality of probes respectively contacting the pads of the micro LED unit on an upper portion of the stage;
a substrate on which an AM driving driver installed on the backplane and transmitting electrical signals for driving the micro LED unit to the plurality of probes according to an external control command is installed; and
and a measuring unit installed under the stage to receive light generated by driving of the micro LED unit and measure the luminous intensity. 8. The method of claim 7,
The backplane has a via hole for connecting the substrate and the probe, the micro LED package inspection apparatus. 8. The method of claim 7,
In the backplane, a plurality of probes corresponding to pads of a plurality of micro LED units are disposed to face each micro LED unit, respectively. 8. The method of claim 7,
Inspection apparatus of a micro LED package, wherein one or more metal materials among metal materials including copper (Cu), titanium (Ti), tungsten (W), and gold (Au) are adhered to the tip of the probe to a predetermined thickness . 8. The method of claim 7,
The measuring unit is
a light receiving sensor array installed to face each of the LED elements of R, G, and B of the micro LED unit to measure light emitted from each LED element; and
The inspection device of the micro LED package, including a transparent plate installed on the light receiving sensor array so that each of the LED elements and the light receiving sensor array has a predetermined separation distance. 8. The method of claim 7,
The inspection apparatus of the micro LED package, which further includes inspection equipment for evaluating defective/good products for each pixel by checking whether the luminous intensity measured by the measurement unit is included in a preset normal range. 13. The method of claim 12,
The test equipment is connected to the AM drive driver through wired communication or wireless communication, and transmits a control command to the AM drive driver to emulate the RGB characteristics of the micro LED unit through the AM drive driver, micro LED package 's inspection device. Micro LED in which each LED element of R, G, and B and an active matrix (AM) driving IC are arranged and molded on the upper surface of the substrate, and pads corresponding to each LED element and the driving IC are positioned on the lower surface of the substrate forming a unit;
generating a micro LED package by cutting the micro LED unit for each package unit;
transmitting an electrical signal for AM driving of the micro LED package in a micro LED unit unit to a pad of each micro LED unit, receiving light generated by the driving of the micro LED unit, and measuring the luminous intensity;
deriving location information of the defective micro LED unit by checking whether the measured luminous intensity is within a preset normal range and inspecting defective/good products for each micro LED unit; and
The inspection method of the micro LED package, comprising the step of transporting and assembling the micro LED unit determined to be good except for the defective micro LED unit based on the location information of the defective micro LED unit.

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