Method for classifying and transferring light emitting diode crystal grains

Abstract

The invention discloses a method for classifying and transferring light-emitting diode crystal grains, which comprises the following steps of: a) obtaining characteristic distribution of a plurality of light-emitting diode crystal grains on a bearing substrate so as to classify the light-emitting diode crystal grains; and b) moving the light emitting diode crystal grains of the same classification to a target substrate. Therefore, the method can classify the light-emitting diode crystal grains according to the characteristics of the light-emitting diode crystal grains, and transfer the light-emitting diode crystal grains with the same classification to the same target substrate, so as to solve the problem of non-uniform characteristic distribution of the light-emitting diode crystal grains.

Description

Technical Field

[0001] The invention relates to the technical field of light emitting diode wafers, in particular to a method for classifying and transferring light emitting diode crystal grains. Background Art

[0002] The existing LED wafer has multiple LED dies. Since the LED dies are affected by the process conditions during the manufacturing process, the LED dies distributed in different areas of the wafer often have different optical or electrical properties. If the LED dies are not classified according to their characteristics and directly applied to related products (such as panels or displays), it is easy to cause uneven light emission of the product, thereby affecting the efficiency of the product. Therefore, the LED dies are classified according to their three-dimensional characteristics, and the LED dies of the same classification level are transferred to a specific area to facilitate subsequent use. Summary of the invention

[0003] In view of the deficiencies of the prior art, the main purpose of the present invention is to provide a method for classifying and transferring LED chips, which can concentrate LED chips with the same characteristics in one area to solve the problem of uneven distribution of characteristics of LED chips.

[0004] To achieve the above main purpose, the method of classifying and transferring LED chips of the present invention includes the following steps: a) obtaining the characteristic distribution of multiple LED chips on a carrier substrate to classify each of the LED chips; and b) moving the LED chips of the same classification to a target substrate.

[0005] Preferably, the step a) includes using an optical camera to obtain an optical image of the LED chips on the carrier substrate, and using an image analyzer to analyze the optical image to obtain the characteristics of each LED chip, and classifying each LED chip according to the characteristics of each LED chip, wherein the characteristics include wavelength or chromaticity.

[0006] Preferably, in the step a), each of the LED chips is classified into a first category and a second category; in the step b), another target substrate is further included, and the LED chips of the first category are moved to the target substrate, and the LED chips of the second category are moved to the other target substrate.

[0007] Preferably, in the step a), another carrier substrate having a plurality of LED grains is further included, and each of the carrier substrates classifies each of the LED grains into a first category and a second category; in the step b), another target substrate is further included, and the LED grains of the first category of each of the carrier substrates are moved to the target substrate, and the LED grains of the second category of each of the carrier substrates are moved to the other target substrate.

[0008] Preferably, in the step b), a transposition device is further included, the transposition device includes a plurality of pick-up heads, each of the pick-up heads has a pick-up range and a plurality of attachment parts located within the pick-up range, and the attachment parts of each of the pick-up heads are used to pick up different numbers of the light-emitting diode chips.

[0009] Through the above technical features, the method of classifying and transferring LED chips of the present invention can classify the LED chips according to their characteristics and transfer the LED chips of the same classification level to the target substrate to solve the problem of uneven distribution of the characteristics of the LED chips.

[0010] The detailed steps and features of the method for classifying and transferring light emitting diode dies provided by the present invention will be described in detail in the subsequent embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A flow chart of the method for classifying and transferring light emitting diode dies of the present invention;

[0012] Figure 2 is a schematic diagram showing a wafer placed in a transfer device, the LED dies of the first category are moved to one substrate, and the LED dies of the second category are moved to another substrate;

[0013] Figure 3 is a schematic diagram showing two wafers, wherein the IE LED dies of the first classification of each wafer are moved to one substrate, and the LED dies of the second classification of each wafer are moved to another substrate;

[0014] Among them, the reference numerals

[0015] 1,2- Method for sorting and transferring light emitting diode dies;

[0016] 10, 10'-wafer;

[0017] 11, 11'-light emitting diode die;

[0018] 20-Transposition device;

[0019] 21- workbench;

[0020] 211-First working area;

[0021] 212- Second working area;

[0022] 213-the third working area;

[0023] 22, 23, 24, 25 - Pickup head;

[0024] 221, 231, 241, 251 - Pickup range;

[0025] 222, 232, 242, 252 - attachment portion;

[0026] 26- transfer device;

[0027] 27- junction;

[0028] 30A, 30B-target substrate;

[0029] C1-first category;

[0030] C2 - second category;

[0031] S1, S2-steps. DETAILED DESCRIPTION

[0032] In order to explain the technical features of the present invention in detail, the method of classifying and transferring light-emitting diode chips of the present invention is described below with reference to the accompanying drawings. It should be noted that the accompanying drawings of the present invention are only schematic diagrams for explaining the technical features of the present invention and are not drawn according to actual size and proportion.

[0033] Please read first Figure 1 The method 1 for classifying and transferring light-emitting diode dies according to the first embodiment of the present invention comprises the following steps:

[0034] a) If Figure 1 In step S1 , characteristic distribution of a plurality of light emitting diode dies on a carrier substrate is obtained to classify each of the light emitting diode dies.

[0035] like Figure 2As shown, in this step S1, a carrier substrate such as a wafer 10 or other supporting substrate for fixing LED chips 11. In this embodiment, the wafer 10 is taken as an example, and the wafer 10 has a plurality of LED chips 11, and these LED chips 11 are arranged in an array. First, a photoluminescence detection method (PL) is used to detect the characteristic distribution of the LED chips 11 of the wafer 10. The PL detection method uses an optical camera (not shown) to photograph the wafer 10 to obtain an optical image of the wafer 10, and then uses an image analyzer (not shown) to analyze the optical image of the wafer 10 to obtain the characteristics of the light emitted by each LED chip 11 (such as wavelength, chromaticity or brightness, etc.). Then, according to the wavelength of the light emitted by each LED chip 11, the distribution of each LED chip 11 on the wafer 10 is confirmed for subsequent classification. In this embodiment, each LED chip 11 of the wafer 10 is classified into a first category C1 (for example, the wavelength of light is 616 nanometers, such as the area within the solid line frame) and a second category C2 (for example, the wavelength of light is 620 nanometers, such as the area outside the solid line frame). The characteristics described above are based on wavelength as an example, but in other embodiments, the parameters or characteristics selected can also be optical parameters such as chromaticity or brightness.

[0036] In other embodiments, the range of each classification may be more irregular or scattered, and there may be more classifications, but the wavelength distribution of light of each LED die 11 can be confirmed through PL detection to facilitate subsequent classification work.

[0037] In addition, step S1 can also be obtained from characteristic classification directly provided by the outside. For example, when the characteristic distribution of the LED die on the carrier substrate is known, that is, the detection has been completed in advance, step S1 allows omitting the PL detection and directly using the detection results for subsequent classification. In addition to PL detection, other detection methods can also be used, such as electroluminescence (EL) detection, which tests the LED die by powering on to obtain the characteristic distribution of the die.

[0038] b) If Figure 1 In step S2, the light emitting diode dies of the same category are moved to a target substrate.

[0039] like Figure 2As shown, in this step S2, a transfer device 20 and two target substrates 30A, 30B need to be provided in advance. The transfer device 20 includes a workbench 21, four pick-up heads 22, 23, 24, 25 and a transfer device 26. The workbench 21 has a first work area 211, a second work area 212 and a third work area 213. The wafer 10 is placed in the first work area 211, and the two target substrates 30A and 30B are placed in the second work area 212; four pick-up heads 22, 23, 24, and 25 are placed in the third work area 213, the pick-up head 22 has a pick-up range 221 and a plurality of attachment portions 222 located in the pick-up range 221, the pick-up head 23 has a pick-up range 231 and a plurality of attachment portions 232 located in the pick-up range 231, the pick-up head 24 has a pick-up range 241 and a plurality of attachment portions 242 located in the pick-up range 241, and the pick-up head 25 has a pick-up range 251 and a plurality of attachment portions 252 located in the pick-up range 251, and each attachment portion 222, 232, 242, and 252 is used to contact and pick up the light-emitting diode chips 11. Since the picking ranges 221, 231, 241, 251 of the picking heads 22, 23, 24, 25 are different, the numbers of the LED chips 11 that can be picked up by the attachment parts 222, 232, 242, 252 are also different. That is, the picking range 221 of the picking head 22 includes 4*4 attachment parts 222, and can pick up 4*4 LED chips 11; the picking range 231 of the picking head 23 includes 3*3 attachment parts 232, and can pick up 3*3 LED chips 11; the picking range 241 of the picking head 24 includes 2*2 attachment parts 242, and can pick up 2*2 LED chips 11; the picking range 251 of the picking head 25 includes three attachment parts 252, and can pick up three LED chips 11. Moreover, each attachment portion 222, 232, 242, 252 picks up the LED chips 11 by a picking force, and the picking force may be (but not limited to) vacuum force, electrostatic force, magnetic force, van der Waals force, mechanical force, etc. The transfer device 26 is connected to the workbench 21, and the transfer device 26 has a coupling portion 27 that can move relative to the workbench 21, and the coupling portion 27 can selectively be combined with one of the four pickup heads 22, 23, 24, 25. In actual operation, the combining portion 27 first moves to the third working area 213 to replace any pick-up head 22, 23, 24, 25. The selected pick-up head 22, 23, 24, 25 moves with the combining portion 27 to the first working area 211 to pick up the LED chips 11 of the wafer 10. The picked-up LED chips 11 move with the combining portion 27 to the second working area 212, so that the picked-up LED chips 11 are moved to the target substrate 30A or another target substrate 30B.

[0040] In this step, the transfer device 20 is used to move the LED dies 11 of the wafer 10 to the target substrate 30A or another target substrate 30B. Specifically, the LED dies 11 of the first category C1 are moved to the target substrate 30A. Since the pick-up head 22 has a pick-up range 221 with the largest area, the joint part 27 uses the pick-up head 221 to move the LED dies 11 of the first category C1 to achieve the purpose of picking up the most LED dies 11 at a time. Next, the remaining LED dies 11 on the wafer 10 are the aforementioned second category C2. The LED dies 11 of the second category C1 are moved to another target substrate 30B. The joint part 27 then uses the pick-up head 23, the pick-up head 24 and the pick-up head 25 to transfer the LED dies 11 of different sizes to another target substrate 30B. In this way, the LED chips 11 of the first and second categories C1 and C2 can be concentrated on the target substrates 30A and 30B respectively, so that the light emitting performance of the LED chips 11 of the first and second categories C1 and C2 is more consistent. In other embodiments, the picking range and picking quantity of the picking head can be changed, and are not limited to the embodiment described.

[0041] However, the present invention is not limited to the first embodiment. Figure 3 , Figure 3 The method 2 for classifying and transferring LED chips according to the second embodiment of the present invention is shown. In this embodiment, step a) includes another wafer 10', the wafer 10' has a plurality of LED chips 11', and each LED chip 11' is classified into the first classification C1 and the second classification C2 according to step a), and then according to step b), the LED chips 11, 11' of the first classification C1 of each wafer 10, 10' are moved to the target substrate 30A respectively, and the LED chips 11, 11' of the second classification C2 of each wafer 10, 10' are moved to the target substrate 30B respectively. In this way, the LED chips 11, 11' of each wafer 10, 10' can be moved to the target substrate 30A or the target substrate 30B according to their classification.

[0042] In summary, the methods 1 and 2 of classifying and transferring LED chips of the present invention can classify the LED chips 11 and 11' according to their characteristics, and transfer the LED chips 11 and 11' of the same classification level to two target substrates 30A and 30B, respectively, to solve the problem of uneven distribution of the characteristic conditions of the LED chips 11 and 11'. Subsequently, the classified LED chips 11 and 11' of the same characteristics on the target substrates 30A and 30B can be used for applications such as mass transfer, and the substrate can be a temporary substrate or a circuit substrate. Furthermore, the actual distribution of the LED chips 11 and 11' of the same characteristic conditions is picked up by different pickup heads to effectively use the chips and avoid chip waste.

[0043] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which belong to the protection scope of the present invention.

Claims

1. A method for sorting and transferring light emitting diode dies, characterized in that: The method comprises the following steps: a) obtaining characteristic distribution of a plurality of light emitting diode dies on a carrier substrate to classify each of the light emitting diode dies; and b) moving the light emitting diode dies of the same classification to a target substrate.

2. The method according to claim 1, characterized in that In the step a), an optical camera is used to obtain an optical image of the LED chips on the carrier substrate, and an image analyzer is used to analyze the optical image to obtain the characteristics of each LED chip, and each LED chip is classified according to the characteristics of each LED chip, which characteristics include wavelength or chromaticity.

3. The method according to claim 1 or 2, characterized in that: In the step a), each of the LED chips is classified into a first category and a second category; in the step b), another target substrate is further included, and the LED chips of the first category are moved to the target substrate, and the LED chips of the second category are moved to the other target substrate.

4. The method according to claim 1 or 2, characterized in that: In the step a), another carrier substrate having a plurality of LED chips is further included, and each of the carrier substrates classifies each of the LED chips into a first category and a second category; in the step b), another target substrate is further included, and the LED chips of the first category of each of the carrier substrates are moved to the target substrate respectively, and the LED chips of the second category of each of the carrier substrates are moved to another of the target substrates respectively.

5. The method according to claim 1, characterized in that In the step b), a transfer device is further included. The transfer device includes a plurality of pick-up heads. Each of the pick-up heads has a pick-up range and a plurality of attachment portions located within the pick-up range. The attachment portions of each of the pick-up heads are used to pick up different numbers of the light-emitting diode dies.

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