Packaging method based on LED flip chip fluorescent powder pre-coating process

Abstract

The invention provides a packaging method based on an LED flip chip fluorescent powder pre-coating process. The packaging method comprises the steps that a flip chip is pre-coated with a fluorescent powder layer; carrying out photoelectric testing on the flip chips to obtain color coordinate data of each flip chip, and generating a distribution diagram; obtaining a color point combination area of the flip chip; judging whether all the flip chips are located in the color point combination area or not according to the distribution diagram and the color point combination area; when one or more flip chips are out of the color point combination area, controlling die bonding equipment to combine the flip chips out of the color point combination area into the color point combination area for die bonding based on the distribution diagram and a preset die bonding algorithm, so that all the flip chips are positioned in the color point combination area; through the packaging method provided by the invention, the lamp beads which do not meet the color area requirement are not generated, so that the packaging yield is greatly improved, and the packaging yield can reach 100%.

Description

Technical Field

[0001] This invention relates to the field of LED packaging technology, and in particular to a packaging method based on LED flip-chip phosphor pre-coating process. Background Technology

[0002] LED white lighting packaging devices have entered the mature market, and industry competition is now focused on improving product luminous efficacy, production yield, production efficiency, and cost reduction. The current packaging process involves: using a standard-mount chip, first performing die bonding, then wire bonding, then applying phosphor coating to the chip, and finally conducting a spectral analysis to separate and package the LEDs that meet the color tolerance requirements.

[0003] However, existing packaging processes use upright chips. On the one hand, the light emission efficiency is limited because the front electrode of the upright chip is blocked. On the other hand, since the phosphor coating process is done later, it is difficult to accurately control the uniformity of the phosphor particle distribution, resulting in a discrete color coordinate distribution of the finished LED beads. During the spectral separation process, a large number of products fall outside the target color tolerance range, resulting in low packaging yield. Especially for the strict three-level color tolerance standard, the yield is usually less than 90%. In addition, the wire bonding and phosphor coating processes are complex and time-consuming, and highly dependent on equipment and manpower, resulting in low production efficiency and high costs.

[0004] Therefore, existing packaging methods suffer from low light extraction efficiency and yield rates typically below 90%. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a packaging method based on LED flip chip phosphor pre-coating process, which aims to solve the technical problems of low light extraction efficiency and yield of less than 90% in the existing packaging methods.

[0006] According to an embodiment of the present invention, a packaging method based on LED flip-chip phosphor pre-coating process is provided, the packaging method comprising: A phosphor layer is pre-coated onto the flip chip using a coating technique to fix the phosphor layer onto the flip chip; Photoelectric testing was performed on flip chips coated with phosphor layers to obtain the color coordinate data of each flip chip, and a distribution map was generated based on the color coordinate data of each flip chip. Obtain the color dot combination area of ​​the flip chip; Based on the distribution map and the color dot combination area, determine whether all flip chips are located within the color dot combination area; When one or more flip chips are outside the color dot combination area, the die bonding equipment is controlled based on the distribution map and the preset die bonding algorithm to combine the flip chips located outside the color dot combination area into the color dot combination area for die bonding, so that all flip chips are located within the color dot combination area. The adhesive is applied to the flip chip using a dispensing device.

[0007] Furthermore, in the step of controlling the die bonding device to combine the flip chip located outside the color dot combination area into the color dot combination area for die bonding based on the distribution map and the preset die bonding algorithm when one or more flip chips are outside the color dot combination area, the preset die bonding algorithm includes: establishing a virtual frame with the color coordinate data in the distribution map, wherein the range selected by the virtual frame includes all the color dot coordinate data; Multiple horizontal reference lines and multiple vertical reference lines are established within the virtual frame, thereby creating multiple cells within the virtual frame; When one or more flip chips are outside the color dot combination area, obtain the distance between each cell and the color dot combination area; Based on the priority of the distance between each cell and the color dot combination area, the die bonding device is controlled to combine the flip chips in the cell into the color dot combination area for die bonding.

[0008] Furthermore, the step of establishing multiple horizontal reference lines and multiple vertical reference lines in the virtual frame to create multiple cells in the virtual frame also includes: The enclosed area formed by each of the aforementioned cells is equal.

[0009] Furthermore, in the step of controlling the die bonding device to bond the flip chips in the cell to the color dot combination area based on the priority of the distance between each cell and the color dot combination area, the method further includes: The die bonding device first bonds at least one flip chip from the cell closest to the color dot combination region to the color dot combination region for die bonding.

[0010] Furthermore, after the step of dispensing adhesive onto the flip chip using a dispensing device, the method further includes: inspecting the dispensed flip chip using a testing device.

[0011] Furthermore, the detection equipment is an AOI (Automated Optical Inspection) device.

[0012] Furthermore, the die bonding equipment is a die bonder.

[0013] Furthermore, after the step of inspecting the flip chip through the testing equipment after dispensing, the method further includes packaging the qualified flip chip.

[0014] Furthermore, in the step of dispensing adhesive onto the flip chip using a dispensing device, the adhesive used for dispensing is a transparent adhesive.

[0015] Furthermore, the dispensing equipment is a dispensing machine.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: Current packaging processes use conventional chip mounting, involving die bonding, wire bonding, phosphor coating, and finally spectral analysis to separate LEDs meeting color tolerance requirements. This method suffers from low light extraction efficiency and a yield typically below 90%. The present invention, however, uses flip chips. A phosphor layer is pre-coated onto the flip chip using a coating technique to fix it in place. Photoelectric testing is then performed on the phosphor-coated flip chips to obtain color coordinate data for each chip, and a distribution map is generated based on this data. The color dot combination regions of the flip chips are then identified. Based on the distribution map and color dot combination regions, it is determined whether all flip chips are located within the color dot combination regions. If one or more flip chips are outside the color dot combination regions... Based on the distribution map and a preset die-bonding algorithm, the die-bonding equipment is controlled to assemble flip chips located outside the color dot combination area into the color dot combination area for die bonding, ensuring that all flip chips are located within the color dot combination area. Finally, adhesive is applied to the flip chips using a dispensing equipment. On the one hand, since there are no electrodes on the front side of the flip chips, the light extraction efficiency is not limited. On the other hand, before the dispensing process, the die-bonding equipment has already been controlled based on the distribution map and the preset die-bonding algorithm to assemble flip chips located outside the color dot combination area into the color dot combination area for die bonding. This means that the beam splitting process (i.e., the LED selection process) is moved forward, preventing the generation of LEDs that do not meet the color zone requirements. This greatly improves the packaging yield, achieving a 100% packaging yield. This effectively solves the technical problems of low light extraction efficiency and yield typically less than 90% in existing technologies. Attached Figure Description

[0017] Figure 1 This is a flowchart of the packaging method based on LED flip-chip phosphor pre-coating process in this invention; Figure 2 This is a distribution map generated from the color coordinate data in this invention; Figure 3 This is a schematic diagram of the virtual frame in this invention; Figure 4This is a schematic diagram illustrating how all flip chips are assembled within the color dot combination area in this invention; Figure 5 This is a schematic diagram of the flip chip in this invention; Figure 6 This is a schematic diagram of a conventionally mounted chip. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figure 6 As shown, this is a standard-mount chip used in existing packaging methods. Figure 6 It is known that the electrodes on the chip can cause blockage, thus limiting the light output efficiency.

[0022] Example This invention provides a packaging method based on LED flip-chip phosphor pre-coating process, comprising the following steps: S10: A phosphor layer is pre-coated onto the flip chip using a coating technique to fix the phosphor layer onto the flip chip.

[0023] For a better understanding of this case, please refer to [link / reference]. Figure 5 As shown, this is the standard chip in this example, which has no electrodes.

[0024] S20: Perform photoelectric testing on the flip chip coated with phosphor layer to obtain the color coordinate data of each flip chip, and generate a distribution map based on the color coordinate data of each flip chip; For a better understanding of the distribution diagram in this embodiment, please refer to [link / reference]. Figure 2 As shown, Figure 2 Each point in the graph represents the color coordinate data of each flip chip, and the graph is composed of multiple color coordinate data.

[0025] S30: Obtain the color dot combination area of ​​the flip chip; It should be noted that the area of ​​color dot combination is Figure 2 The area selected by the ellipse, given Figure 2 This is an example to facilitate the explanation of the color dot combination area, and is not intended to limit the scope of the color dot combination area. Color dot combination areas with other shapes and outlines are all within the scope of this application. Since color dot combination areas with other shapes and outlines are conventional prior art in this field, they are not specifically limited here.

[0026] S40: Determine whether all flip chips are located within the color dot combination area based on the distribution map and the color dot combination area; S50: When one or more flip chips are outside the color dot combination area, the die bonding equipment is controlled based on the distribution map and the preset die bonding algorithm to combine the flip chips located outside the color dot combination area into the color dot combination area for die bonding, so that all flip chips are located within the color dot combination area. Specifically, in the step of controlling the die bonding device to combine the flip chip located outside the color dot combination area into the color dot combination area for die bonding when one or more flip chips are outside the color dot combination area based on the distribution map and the preset die bonding algorithm, the preset die bonding algorithm includes: establishing a virtual frame with the color coordinate data in the distribution map, and the range of the virtual frame includes all the color dot coordinate data. Create multiple horizontal and vertical reference lines within a virtual frame, thus creating multiple cells within the virtual frame; When one or more flip chips are outside the color dot combination area, obtain the distance between each cell and the color dot combination area; Based on the priority of the distance between each cell and the color dot combination area, the flip chip combination in the cell of the die bonding device is controlled to be placed within the color dot combination area for die bonding.

[0027] It should be noted that the enclosed area formed by each cell is equal. For a better understanding of this case, please refer to [link / reference needed]. Figure 3 As shown.

[0028] Specifically, the step of controlling the flip chip assembly in the die bonding equipment cell to be within the color dot combination area for die bonding, based on the priority of the distance between each cell and the color dot combination area, also includes: The die bonding equipment first bonds at least one flip chip from the cell closest to the color dot combination area to the color dot combination area for die bonding.

[0029] It should be noted that, to improve die bonding efficiency, in this implementation, the die bonding equipment will first bond at least one flip chip from the cell closest to the color dot combination area to the color dot combination area for die bonding, and then sequentially bond other flip chips to the color dot combination area according to their distance. This improves die bonding efficiency. It should be noted that the die bonding equipment is a die bonder; please refer to [link to relevant documentation] for details. Figure 4 As shown.

[0030] S60: Apply adhesive to the flip chip using a dispensing device.

[0031] Furthermore, in the step of dispensing adhesive onto the flip chip using dispensing equipment, the adhesive used is transparent adhesive. It should be noted that the dispensing equipment is a dispensing machine.

[0032] S70: Further, after the step of dispensing adhesive onto the flip chip using a dispensing device, the method further includes: inspecting the dispensed flip chip using a testing device.

[0033] Furthermore, the inspection equipment is an AOI device, which is used for external inspection and unloading.

[0034] S80: After the flip chip is inspected by the testing equipment after dispensing, the process also includes packaging the qualified flip chip.

[0035] In summary, the packaging method based on LED flip-chip phosphor pre-coating process in the first embodiment of the present invention has at least the following advantages compared with the packaging methods of the prior art that use conventional chips: Current packaging processes use conventional chip mounting, involving die bonding, wire bonding, phosphor coating, and finally spectral analysis to separate LEDs meeting color tolerance requirements. This method suffers from low light extraction efficiency and a yield typically below 90%. The present invention, however, uses flip chips. A phosphor layer is pre-coated onto the flip chip using a coating technique to fix it in place. Photoelectric testing is then performed on the phosphor-coated flip chips to obtain color coordinate data for each chip, and a distribution map is generated based on this data. The color dot combination regions of the flip chips are then identified. Based on the distribution map and color dot combination regions, it is determined whether all flip chips are located within the color dot combination regions. If one or more flip chips are outside the color dot combination regions... Based on the distribution map and a preset die-bonding algorithm, the die-bonding equipment is controlled to assemble flip chips located outside the color dot combination area into the color dot combination area for die bonding, ensuring that all flip chips are located within the color dot combination area. Finally, adhesive is applied to the flip chips using a dispensing equipment. On the one hand, since there are no electrodes on the front side of the flip chips, the light extraction efficiency is not limited. On the other hand, before the dispensing process, the die-bonding equipment has already been controlled based on the distribution map and the preset die-bonding algorithm to assemble flip chips located outside the color dot combination area into the color dot combination area for die bonding. This means that the beam splitting process (i.e., the LED selection process) is moved forward, preventing the generation of LEDs that do not meet the color zone requirements. This greatly improves the packaging yield, achieving a 100% packaging yield. This effectively solves the technical problems of low light extraction efficiency and yield typically less than 90% in existing technologies.

[0036] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A packaging method based on LED flip-chip phosphor pre-coating process, characterized in that, Encapsulation methods include: A phosphor layer is pre-coated onto the flip chip using a coating technique to fix the phosphor layer onto the flip chip; Photoelectric testing was performed on flip chips coated with phosphor layers to obtain the color coordinate data of each flip chip, and a distribution map was generated based on the color coordinate data of each flip chip. Obtain the color dot combination area of ​​the flip chip; Based on the distribution map and the color dot combination area, determine whether all flip chips are located within the color dot combination area; When one or more flip chips are outside the color dot combination area, the die bonding equipment is controlled based on the distribution map and the preset die bonding algorithm to combine the flip chips located outside the color dot combination area into the color dot combination area for die bonding, so that all flip chips are located within the color dot combination area. The adhesive is applied to the flip chip using a dispensing device.

2. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 1, characterized in that, In the step of controlling the die bonding device to combine the flip chip located outside the color dot combination area into the color dot combination area for die bonding based on the distribution map and the preset die bonding algorithm when one or more flip chips are outside the color dot combination area, the preset die bonding algorithm includes: establishing a virtual frame with the color coordinate data in the distribution map, and the range selected by the virtual frame includes all the color dot coordinate data; Multiple horizontal reference lines and multiple vertical reference lines are established within the virtual frame, thereby creating multiple cells within the virtual frame; When one or more flip chips are outside the color dot combination area, obtain the distance between each cell and the color dot combination area; Based on the priority of the distance between each cell and the color dot combination area, the die bonding device is controlled to combine the flip chips in the cell into the color dot combination area for die bonding.

3. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 2, characterized in that, The step of establishing multiple horizontal reference lines and multiple vertical reference lines in the virtual frame, thereby establishing multiple cells in the virtual frame, further includes: The enclosed area formed by each of the aforementioned cells is equal.

4. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 3, characterized in that, The step of controlling the die bonding device to bond the flip chips in the cell to the color dot combination area based on the priority of the distance between each cell and the color dot combination area further includes: The die bonding device first bonds at least one flip chip from the cell closest to the color dot combination region to the color dot combination region for die bonding.

5. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 1, characterized in that, After the step of dispensing adhesive onto the flip chip using a dispensing device, the method further includes: inspecting the dispensed flip chip using a testing device.

6. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 5, characterized in that, The detection equipment is an AOI device.

7. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 1, characterized in that, The die bonding equipment is a die bonder.

8. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 5, characterized in that, After the flip chip is inspected by the testing equipment following the dispensing process, the method further includes packaging the qualified flip chip.

9. The packaging method based on LED flip-chip phosphor pre-coating process according to any one of claims 1-8, characterized in that, In the step of dispensing adhesive onto the flip chip using a dispensing device, the adhesive being dispensed is a transparent adhesive.

10. The packaging method based on LED flip-chip phosphor pre-coating process according to claim 9, characterized in that, The dispensing equipment is a dispensing machine.

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