LED packaging unit and preparation method thereof

Abstract

The invention discloses an LED packaging unit and a preparation method thereof, and relates to the technical field of LED packaging, and the preparation method of the LED packaging unit comprises the following steps: providing a substrate, an LED chip and a control chip; the control chip is placed on the first surface of the substrate, a port electrode of the control chip is in contact with the first surface, the multiple LED chips with the same light emitting color are randomly distributed in the same target area, and the multiple LED chips located in the same target area form a single-color LED group; a packaging body wrapping the control chip and all the LED chips is arranged at the outer part of the substrate; and preparing a lower wiring layer on the lower surface of the packaging body, and preparing an upper wiring layer on the upper surface of the packaging body. According to the preparation method of the LED packaging unit, the requirement for the position precision of a single LED chip can be lowered, and the use reliability of the prepared LED packaging unit is improved.

Description

Technical Field

[0001] This invention relates to the field of LED packaging technology, and in particular to an LED packaging unit and its manufacturing method. Background Technology

[0002] LED chips (such as Micro LEDs or mini LEDs) are commonly used in light-emitting devices such as displays. Some LED package units include a control chip and three LED chips packaged together. The control chip controls the LED chips to emit light. The three LED chips are usually red, green, and blue LED chips.

[0003] The aforementioned LED packaging units have relatively poor reliability. For example, if one LED chip fails, the entire LED packaging unit will not emit light properly. Moreover, existing LED packaging units require high positional accuracy for the LED chips.

[0004] In addition, since the conductive lines in the wiring layer are usually located in the same layer, the conductive lines connected to the electrodes of the LED chip are generally located on the outside of the LED chip near the LED packaging unit, resulting in a relatively large overall size of the LED packaging unit.

[0005] Therefore, it is necessary to improve the existing technology to overcome the aforementioned defects.

[0006] The above content is only used to help understand the technical solution of this application and does not constitute an admission that the above is prior art. Summary of the Invention

[0007] The purpose of this invention is to provide an LED packaging unit and its manufacturing method to improve the operational reliability of the LED packaging unit.

[0008] To achieve the above-mentioned objectives, the present invention provides a method for preparing an LED packaging unit, characterized by comprising the following steps:

[0009] S1. Provide a substrate, an LED chip, and a control chip, wherein the LED chip includes an electrode pair, and the electrode pair includes a first electrode and a second electrode located on opposite sides of the LED chip;

[0010] S2. The control chip is placed on the first surface of the substrate, with the port electrode of the control chip in contact with the first surface. Multiple LED chips of the same emitting color are randomly scattered in the same target area, and effective LED chips with the second electrode in contact with the first surface and ineffective LED chips with the second electrode not in contact with the first surface are randomly formed. Multiple LED chips located in the same target area constitute a monochrome LED group.

[0011] S3. An encapsulation covering the control chip and all the LED chips is provided on the outside of the substrate;

[0012] S4. A lower wiring layer is prepared on the lower surface of the package, and an upper wiring layer is prepared on the upper surface of the package.

[0013] Furthermore, the LED chips are divided into first-color LED chips, second-color LED chips, and third-color LED chips according to their emission color, and in step S2, three monochrome LED groups are formed.

[0014] Furthermore, in step S2, the number of LED chips contained in the monochrome LED group is no less than 8.

[0015] Furthermore, in step S2, the step of randomly scattering multiple LED chips of the same emission color in the same target area includes: pouring multiple LED chips of the same emission color into the target area.

[0016] Furthermore, in step S2, the step of randomly distributing multiple LED chips of the same emission color in the same target area includes the following steps:

[0017] Multiple LED chips of the same color are placed in a liquid to form an LED paste;

[0018] The LED paste is transferred to the target area.

[0019] Furthermore, the LED paste is transferred to the target area by screen printing, embossing, spraying, or printing.

[0020] Further, in step S4, preparing the lower wiring layer on the lower surface of the package includes the following steps:

[0021] Remove the substrate to expose the second electrode of the active LED chip and the port electrode of the control chip;

[0022] A lower conductive line is formed on the lower surface of the package, the lower surface being the surface of the package that exposes the second electrode of the effective LED chip and the port electrode of the control chip;

[0023] A lower insulating layer is prepared on the lower surface, and the lower insulating layer covers the surface of the lower conductive wire;

[0024] Port pads are prepared on the surface of the lower insulating layer;

[0025] A second metallized via is prepared, communicating with the lower conductive line and the port pad.

[0026] Further, in step S4, preparing a wiring layer on the upper surface of the package includes the following steps:

[0027] An upper conductive line and a first metallized via connecting the upper conductive line and the port pad are prepared on the upper surface of the package.

[0028] An insulating layer is prepared on the upper surface of the package, and the upper insulating layer covers the surface of the upper conductive line.

[0029] Furthermore, in step S4, before preparing the upper wiring layer, the following step is also included: thinning the upper surface of the package to expose the first electrode of the LED chip, wherein the initial thickness of the first electrode 10 is not less than 10 μm.

[0030] Furthermore, the center of gravity of the LED chip is close to the second electrode;

[0031] The LED chip includes a metal mass block connected to its second electrode; and / or,

[0032] The cross-sectional area of ​​the end where the second electrode of the LED chip is located is larger than the cross-sectional area of ​​the end where the first electrode is located.

[0033] Furthermore, the LED chip is in the shape of a cuboid or a cube;

[0034] The LED chip includes two sets of electrode pairs, and the second electrodes of the two sets of electrode pairs are located on two adjacent surfaces of the LED chip; or,

[0035] The LED chip includes three sets of electrode pairs, and the second electrodes of the three sets of electrode pairs are located on three adjacent surfaces of the LED chip.

[0036] Secondly, the present invention provides an LED packaging unit, characterized in that it comprises:

[0037] A single-color LED cluster includes multiple LED chips that emit the same color of light, and each LED chip includes a first electrode and a second electrode located on both sides thereof;

[0038] The control chip includes multiple port electrodes. The position and orientation of the LED chips in the monochromatic LED group are random. LED chips whose second electrode is located on the same plane as the port electrode are called effective LED chips, and LED chips whose second electrode is not located on the same plane as the port electrode are called invalid LED chips.

[0039] The package covers the control chip and all the LED chips.

[0040] An upper wiring layer is disposed on the upper surface of the package; and,

[0041] A lower wiring layer is disposed on the lower surface of the package, and the control chip is electrically connected to the second electrode of the effective LED chip through the lower wiring layer.

[0042] Furthermore, the lower wiring layer includes a port assembly, which includes a plurality of exposed port pads, and the port assembly is electrically connected to the LED chip and the control chip.

[0043] Furthermore, the port assembly includes a power supply port pad and a ground port pad;

[0044] Both the power supply port pad and the grounding port pad are electrically connected to the control chip.

[0045] The active LED chip is electrically connected to the power supply port pad or the grounding port pad.

[0046] Furthermore, all of the port pads are exposed on the same surface of the LED package unit. The upper wiring layer includes an upper conductive line electrically connected to the first electrode of the active LED chip and an upper insulating layer covering the upper conductive line. The upper conductive line and the power supply port pad or the ground port pad are connected through a first metallized via through the package.

[0047] Furthermore, the LED packaging unit includes three monochrome LED groups, each of which has an LED chip with a different emission color. The first electrode of the effective LED chip in each of the three monochrome LED groups is connected to the power supply port pad or the ground port pad via the same upper conductive line.

[0048] Furthermore, the lower wiring layer includes a lower conductive line and a lower insulating layer covering the lower conductive line, and each port pad and the control chip are connected through a second metallized via passing through the lower insulating layer and the lower conductive line;

[0049] The port electrodes of the control chip and the monochrome LED group are connected by a bottom conductive line.

[0050] Furthermore, the lower conductive line connected to the monochrome LED group has a widened connection portion, and the LED chips of the monochrome LED group are located on the connection portion.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] According to at least one embodiment of the present invention, the method for fabricating an LED packaging unit involves randomly distributing multiple LED chips of the same emission color in the same target area to form a monochromatic LED group. Since the monochromatic LED group typically includes a large number of effective LED chips, even if there are damaged LED chips, the monochromatic LED group can still emit light normally, greatly reducing the reliability requirements of the LED chips and increasing the process fault tolerance. In addition, the random distribution method greatly reduces the positional requirements of individual LED chips, avoids the high precision requirements of traditional mass transfer, and eliminates the need for expensive high-precision mass transfer equipment, thus greatly improving production efficiency and reducing production costs. Attached Figure Description

[0053] Figure 1 This is a top view schematic diagram of the control chip and LED chip placed on the substrate in some embodiments of the present invention.

[0054] Figure 2 This is a cross-sectional schematic diagram showing the control chip and LED chip placed on a substrate in some embodiments of the present invention.

[0055] Figure 3 These are schematic diagrams of several different orientations of LED chips in some embodiments of the present invention.

[0056] Figure 4 yes Figure 2 The diagram shown is a schematic of the structure with an encapsulation.

[0057] Figure 5 This is a cross-sectional schematic diagram of an LED packaging unit in some embodiments of the present invention.

[0058] Figure 6 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0059] Figure 7 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0060] Figure 8 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0061] Figure 9 This is a three-dimensional schematic diagram of an LED chip according to some embodiments of the present invention.

[0062] Figure 10 yes Figure 9 The diagram shows the front view of the LED chip.

[0063] Figure 11 This is a three-dimensional schematic diagram of an LED chip according to some embodiments of the present invention.

[0064] Figure 12 This is a schematic diagram showing the positions of the bottom conductive line, port pads, and LED chip in some embodiments of the present invention.

[0065] Figure 13 This is a schematic diagram showing the positions of the lower conductive line, port pad, and upper conductive line in some embodiments of the present invention.

[0066] Figure 14 This is a schematic diagram showing the location of the port pads of the LED packaging unit in some embodiments of the present invention.

[0067] Figure 15 This is a cross-sectional schematic diagram of an LED packaging unit according to some embodiments of the present invention, which is related to... Figure 5 The cross-sectional directions and positions are different.

[0068] Figure 16 yes Figure 4 The diagram shown illustrates the process of removing the substrate from the structure.

[0069] Figure 17 yes Figure 16 The diagram shown illustrates the configuration of the conductive wires.

[0070] Figure 18 This is a schematic diagram showing a lower insulating layer on the lower conductive line, which is similar to... Figure 17 The cross-sectional directions and positions are different.

[0071] Figure 19 yes Figure 18 The diagram shown illustrates the configuration of the port pads.

[0072] Figure 20 yes Figure 19 The diagram shown illustrates the configuration of the second metallized via 522.

[0073] Figure 21 yes Figure 20 The diagram shown illustrates the structure with conductive lines installed.

[0074] Figure 22 This is a top view schematic diagram of the control chip and LED chip placed on the substrate in some embodiments of the present invention.

[0075] Figure 23 This is a cross-sectional schematic diagram of an LED packaging unit in some embodiments of the present invention. Detailed Implementation

[0076] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0077] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0078] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0079] Some embodiments of the present invention provide a method for fabricating an LED packaging unit, which includes the following steps:

[0080] S1. A substrate 6, an LED chip 1, and a control chip 2 are provided. The LED chip 1 includes an electrode pair, comprising a first electrode 10 and a second electrode 11 located on opposite sides of the LED chip 1. One of the first electrode 10 and the second electrode 11 is a positive electrode, and the other is a negative electrode. It is understood that the positions of the first electrode 10 and the second electrode 11 determine the direction of current flow to illuminate the LED chip 1. In some embodiments, the LED chip 1 is a vertically structured LED chip. By using a vertical chip, luminous efficiency can be guaranteed while significantly reducing the size of the LED chip.

[0081] S2. For example Figure 1 and Figure 2 As shown, the control chip 2 is placed on the first surface 60 of the substrate 6, and the port electrode 20 of the control chip 2 is in contact with the first surface 60. Multiple LED chips 1 with the same emission color are randomly scattered in the same target area 61. Multiple LED chips 1 located in the same target area 61 constitute a monochrome LED group. Figure 1The approximate area of ​​the target region 61 is shown in the double-dotted line box. It is understood that the positions and orientations (e.g., electrode orientation) of the randomly distributed LED chips 1 are random. Therefore, the second electrode 11 of the LED chip 1 may or may not be in contact with the first surface 60. LED chips 1 whose second electrode 11 is in contact with the first surface 60 are referred to as valid LED chips 1a, and LED chips 1 whose second electrode 11 is not in contact with the first surface 60 are referred to as invalid LED chips 1b. Figure 3 The diagram shows the possible orientations of several LED chips 1 when they are randomly distributed. LED chips 1 that are in contact with the target area 61 by the second electrode 11 are called effective LED chips 1a because they can be driven to emit light normally. The other LED chips 1 cannot be driven to emit light normally and are called ineffective LED chips 1b.

[0082] It should be noted that the target area 61 is a virtual area defined by the user, and a target area 61 with clear boundaries may not necessarily exist in the actual product. Furthermore, the order in which the LED chip 1 and the control chip 2 are placed is not limited; for example, the control chip 2 can be placed first, followed by the LED chip 1, or vice versa, or they can be placed simultaneously.

[0083] S3. For example Figure 4 As shown, a package 3 covering the control chip 2 and all the LED chips 1 is provided on the outside of the substrate 6.

[0084] S4. For example Figure 5 As shown, a lower wiring layer 52 is prepared on the lower surface of the package 3, and an upper wiring layer 51 is prepared on the upper surface of the package 3. The lower wiring layer 52 electrically connects one port electrode 20 of the control chip 2 to the second electrode 11 of all effective LED chips 1a in the same monochromatic LED group, so that the control chip 2 can control all effective LED chips 1a in the monochromatic LED group to emit light. It is understood that the preparation order of the lower wiring layer 52 and the upper wiring layer 51 can be interchanged.

[0085] It is understandable that although the ineffective LED chip 1b cannot be driven to emit light, as long as there is one emitting LED chip 1 in the monochrome LED group, the monochrome LED group can achieve the function of emitting light. Furthermore, under constant current source driving conditions, when the forward conduction voltage (Vf) of multiple parallel LED chips is similar, the total current output by the constant current source is approximately evenly distributed among the LED chips. Since the total current is constant, the total luminous power and overall brightness remain unchanged regardless of the number of parallel LED chips. In other words, even if the number of effective LED chips 1a in the monochrome LED group is different, as long as the monochrome LED group is driven by a constant current source, the luminous brightness of the monochrome LED group can be nearly uniform. Of course, more accurate uniformity can be further optimized through algorithms. The more emitting LED chips 1 there are in the monochrome LED group, the more uniform the brightness of the pixels corresponding to that monochrome LED group will be.

[0086] Understandably, since a monochrome LED group usually has a large number of effective LED chips 1a, such as two, three or more effective LED chips 1a, even if there are damaged LED chips 1, the monochrome LED group can still emit light normally, which greatly reduces the reliability requirements of LED chips 1, increases the process fault tolerance, and makes the LED packaging unit more reliable in use.

[0087] Understandably, by randomly distributing the LED chips 1 in the target area 61, the positional requirements for each individual LED chip 1 can be greatly reduced, avoiding the high precision requirements of traditional mass transfer. This eliminates the need for expensive, high-precision mass transfer equipment, significantly improving production efficiency and reducing production costs. Furthermore, invalid LED chips 1b can be retained in the target area 61 without requiring processing, greatly simplifying the process.

[0088] LED chip 1 can be a Micro LED chip or a Mini LED chip. Because there is no need for point-to-point mass transfer, the size of LED chip 1 can be made very small, and the cost of a single LED chip 1 is lower. A large number of LED chips 1 can be randomly distributed in a small target area 61, such as a dozen, dozens, hundreds or even more LED chips 1, thereby improving the reliability and uniformity of light emission.

[0089] It is understandable that, given a large number of randomly distributed LED chips 1, it is almost inevitable that there will be a valid LED chip 1a in the target area 61. In addition, the number of valid LED chips 1a in the target area 61 can be further increased through various means.

[0090] In some embodiments, the center of gravity of the LED chip 1 is set close to the second electrode 11. This makes the LED chip 1 more stable when its second electrode 11 is facing downwards, especially when randomly distributed across at least the target region 61. Therefore, the probability of the second electrode 11 of the LED chip 1 facing downwards is significantly increased. As a possible example, refer to... Figure 6 The LED chip 1 includes a metal mass block 110 connected to its second electrode 11. The center of gravity of the LED chip 1 is changed by adding the metal mass block 110. As a feasible example, such as... Figure 7 As shown, the second electrode 11 of the LED chip 1 is widened and / or thickened to bring its center of gravity closer to the second electrode 11. As a possible example, such as... Figure 8 As shown, the cross-sectional area of ​​the end where the second electrode 11 of the LED chip 1 is located is larger than the cross-sectional area of ​​the end where the first electrode 10 is located, and its overall shape is smaller at the top and larger at the bottom, so that its center of gravity is close to the second electrode 11. It can be understood that the above examples can be used in combination to further ensure the effect.

[0091] In some embodiments, the LED chip 1 is in the shape of a cuboid or a cube, and includes at least two sets of electrode pairs. The second electrodes 11 of the two sets of electrode pairs are located on two adjacent surfaces of the LED chip 1. Similarly, each of the two second electrodes 11 is provided with a first electrode 10, and the second electrode 11 and the first electrode 10 of the same electrode pair are located on two opposite surfaces of the LED chip 1. Figure 9 and Figure 10 A schematic diagram is shown when two sets of electrodes are provided on the LED chip 1. Because the number of second electrodes 11 on the surface of the LED chip 1 increases, the probability of the second electrodes 11 of the LED chip 1 contacting the target area 61 can be significantly increased. Specifically, assuming that the probability of each side of the LED chip 1 facing down is the same, then the probabilities of having a downward-facing second electrode 11 are one-sixth and one-third when the second electrodes 11 are provided on only one side and on both sides, respectively. Optionally, as... Figure 11 As shown, the LED chip 1 includes three sets of electrode pairs. The second electrode 11 of the three sets of electrode pairs is located on three adjacent surfaces of the LED chip 1. Assuming that the probability of each surface of the LED chip 1 facing down is the same, when three sets of electrode pairs are set, the probability of the second electrode 11 of the LED chip 1 facing down is one in half, which greatly increases the probability. When the number of randomly distributed LED chips 1 in the target area 61 is 10, the probability of having a valid LED chip 1 can be greater than 99.9%. If combined with the aforementioned center of gravity adjustment or other methods, the probability can be further improved. For example, the center of gravity of the LED chip 1 can be set close to one of the second electrodes 11, or it can be set close to the connection position of two or three second electrodes 11.

[0092] Optionally, the surface of the second electrode 11 is provided with conductive adhesive, so that when the second electrode 11 comes into contact with the target area 61, it is less likely to flip or roll, thereby improving the reliability of the contact between the second electrode 11 and the target area 61.

[0093] Understandably, the probability of the second electrode 11 being on the bottom can also be increased in other ways. For example, the probability can be increased by applying an external magnetic field: a small amount of magnetic metal can be deposited on the side of the second electrode 11 or unidirectional magnetic particles can be adhered, and a magnetic field can be applied below the substrate 6 to align the LED chip 1 in the correct orientation. Alternatively, the probability can be increased by applying an external sound field or electric field.

[0094] Optionally, each group of monochromatic LEDs contains no fewer than 8 LED chips 1 to increase the probability of a valid LED chip 1a appearing.

[0095] In step S2, multiple LED chips 1 with the same emitting color are randomly scattered on the same target area 61, which can be achieved in various ways.

[0096] In some embodiments, the LED chip 1 is directly poured onto the target area 61. Specifically, a large number of LED chips 1 can be placed in a storage container, and then the LED chips 1 are released into the target area 61 through the storage container. Since the posture of the LED chip 1 in the storage container is random, and the randomness of the LED chip 1 is also increased during the falling process, the LED chips 1 are also randomly distributed after falling into the target area 61. Specifically, the position and posture (e.g., the position of the electrodes) of the LED chip 1 are diverse.

[0097] In other embodiments, randomly distributing the LED chips 1 over at least the target area 61 includes the following steps:

[0098] A1. Place multiple LED chips 1 of the same emitting color in a liquid to form an LED slurry.

[0099] A2. Transfer the LED paste to the target area 61.

[0100] It is understandable that the more uniformly the LED chip 1 is distributed in the liquid, the more uniformly the LED chip 1 will be distributed in the target area 61 after it is transferred to the target area 61. When the volume of LED paste carried by each target area 61 is similar, the number of LED chips 1 contained in each target area 61 is also relatively similar, which is conducive to increasing the uniformity of light emission.

[0101] Since the orientation of LED chip 1 in the liquid is random, its position and orientation in the target area 61 are also random after the LED slurry is transferred to the target area 61, resulting in diverse electrode positions for LED chip 1. It is understandable that by controlling the concentration of LED chip 1 (i.e., the number of LED chips 1 contained in a unit volume of slurry), the number of LED chips 1 that may exist in the target area 61 can be controlled, thereby controlling the probability of the presence of effective LED chips 1.

[0102] The liquid can be deionized water, an aqueous solution with added surfactants, an organic solvent, or an inert liquid with a density higher than water. Understandably, the liquid does not dissolve, expand, encapsulate, or bond materials, nor does it undergo electrochemical reactions with metals.

[0103] Understandably, the liquid on substrate 6 can be removed by methods such as solvent evaporation, solution annealing, or capillary drainage. For liquids that can be cured, they can also be cured and retained.

[0104] Optionally, in step A2, the LED paste is transferred to the target area 61 by means of screen printing, embossing, spraying, or printing. In screen printing, the LED paste is embossed onto the target area 61 using a screen mask. In embossing, the LED paste is first applied to an open stencil and then transferred to the target area. In spraying, the LED paste is sprayed onto the surface of the target area. Printing can be, for example, inkjet printing or dispensing printing.

[0105] In some embodiments, LED chips 1 are classified into first-color LED chips, second-color LED chips, and third-color LED chips according to their emission colors. In step S2, as... Figure 1 As shown, three monochromatic LED groups are formed, each consisting of a first-color LED chip, a second-color LED chip, and a third-color LED chip, to emit different light. It can be understood that the different monochromatic LED groups are electrically connected to different port electrodes 20 of the control chip 2, so that the control chip 2 can independently control the light emission of each monochromatic LED group.

[0106] Optionally, among the first-color LED chip, the second-color LED chip, and the third-color LED chip, one is used to emit red light, one is used to emit green light, and one is used to emit blue light, for example, emitting red, green, and blue light respectively. In the figure, LED chip 1 marked with the letters R, G, and B represents the first-color LED chip, the second-color LED chip, and the third-color LED chip, respectively.

[0107] In step S2, LED chips 1 of corresponding light-emitting colors can be randomly distributed in the target areas 61 carrying LED chips of different colors in stages. For ease of description, the target areas 61 used to carry the first-color LED chips, the second-color LED chips, and the third-color LED chips are referred to as the first-color target area 61a, the second-color target area 61b, and the third-color target area 61c, respectively. For example, the LED chips 1 of corresponding light-emitting colors can be randomly distributed in the first-color target area 61a, the second-color target area 61b, and the third-color target area 61c in three stages by means of screen printing or inkjet printing. Specifically, the first-color LED chips 1 are printed on all the first-color target areas 61a first, then the second-color LED chips 1 are printed on all the second-color target areas 61b, and finally the third-color LED chips 1 are printed on all the third-color target areas 61c (of course, the order can be adjusted). When randomly scattering a certain color LED chip 1 by tilting, an auxiliary plate can be set up to block the target area that does not correspond to that color LED chip 1. The auxiliary plate can be configured to only expose the corresponding target area, ensuring that the LED chip 1 is reliably scattered in the desired area. For example, when scattering the first color LED chip 1 in the first color target area 61a, the auxiliary plate can expose the first color target area 61a while blocking other areas. Thus, when tilting the first color LED chip 1, it will not be mistakenly located in the second color target area 61b or the third color target area 61c. A similar method can be used when tilting other color LED chips 1.

[0108] In some embodiments, such as Figure 5 As shown, the lower wiring layer 52 includes a lower conductive line 520 and a lower insulating layer 521 covering the lower conductive line 520, and the upper wiring layer 51 includes an upper conductive line 510 and an upper insulating layer 511 covering the upper conductive line 510. The port electrodes 20 of the control chip 2 and each monochrome LED group are connected through independent lower conductive lines 520, as shown. Figure 12 As shown, Figure 12 A schematic diagram of the distribution of the lower conductive lines 520 in some embodiments is shown. Figure 12 In the control chip 2, each port electrode 20 is connected to each monochrome LED group via lower conductive lines 520a, 520b, and 520c. Each of the lower conductive lines 520a, 520b, and 520c connected to the monochrome LED group has a connection portion 5200. The monochrome LED group is located on the connection portion 5200, and the second electrode 11 of the effective LED chip 1a is electrically connected to the connection portion 5200. For example... Figure 13 As shown, Figure 13A schematic diagram showing the positions of the upper conductive line 510 and the lower conductive line 520 is provided. The upper conductive line 510 is at least partially positioned opposite the connecting portion 5200 and is electrically connected to the first electrode 10 of the active LED chip 1a. The target region 61 corresponds to the area where the projections of the upper conductive line 510 and the connecting portion 5200 overlap along the thickness direction of the package 3. Optionally, the projection of the upper conductive line 510 completely covers the connecting portion 5200; in this case, the outer contour of the connecting portion 5200 can be considered as the region of the target region 61.

[0109] Optionally, the connection portion 5200 is widened to provide a larger area for carrying the LED chip 1.

[0110] In some embodiments, the lower wiring layer 52 further includes a plurality of port pads 40, which are connected to corresponding ports of the control chip 2 via lower conductive lines 520. Optionally, the lower wiring layer 52 includes four port pads 40, such as... Figure 13 and Figure 14 As shown, these are the power supply port pad 40a, the first data port pad 40b, the second data port pad 40c, and the ground port pad 40d. The power supply port pad 40a, the first data port pad 40b, the second data port pad 40c, and the ground port pad 40d are all connected to the corresponding ports of the control chip 2 via independent lower conductive lines 520d, 520e, 520f, and 520g, respectively, to achieve electrical connection with the control chip 2. (Refer to...) Figure 13 and Figure 15 It is understandable that the lower conductive lines 520d, 520e, 520f, 520g and the corresponding port pads 40a, 40b, 40c and 40d are connected through the second metallized via 522.

[0111] The power supply port pad 40a is used to connect to the power supply line to provide a high-level driving voltage for the control chip 2 and the LED chip 1.

[0112] The first data port pad 40b and the second data port pad 40c are used for signal transmission, such as input and output signals, to receive or send data. The control chip 2 can control the effective LED chip 1a within the corresponding monochrome LED group to emit light according to the control signal input from the first data port pad 40b. The control chip 2 can also transmit signals outward through the second data port pad 40c to control the emission of other LED package units. The control chip 2 can also provide feedback on relevant information about the LED package unit itself through either the first data port pad 40b or the second data port pad 40c.

[0113] For example, two or more LED package units can be connected in series. The second data port pad 40c of the preceding LED package unit is connected to the first data port pad 40b of the following LED package unit. The preceding LED package unit receives control signals through its first data port pad 40b and controls the corresponding monochromatic LED group to emit light. At the same time, it transmits the control signals to the following LED package unit through its second data port pad 40c. The following LED package unit controls its monochromatic LED group to emit light according to the control signals. The following LED package unit can also feed back information, such as fault information, to the preceding LED package unit.

[0114] The grounding port pad 40d is used to connect to the ground wire.

[0115] It is understood that the port pad 40 described above is only an example, and the LED packaging unit may include other types of port pads 40, and the number of port pads 40 may also be increased or decreased.

[0116] In some embodiments, all port pads 40 are located on the underside of the package 3 and exposed on the lower surface of the LED package unit, so that the LED package unit can be connected to an external circuit board through its port pads 40.

[0117] The upper conductive line 510 is connected to at least one port pad 40 through a first metallized via 50 passing through the package 3. Specifically, the upper conductive line 510 can be connected to a power supply port pad 40a or a ground port pad 40d. When the first electrode 10 is positive, the upper conductive line 510 is connected to the power supply port pad 40a, and the upper conductive line 510 provides a high-level voltage. The control chip 2 controls the second electrode 11 of the active LED chip 1a to be grounded or connected to a low level to drive the active LED chip 1a to emit light. When the second electrode 11 is negative, the upper conductive line 510 is connected to the ground port pad 40d, and the control chip 2 controls the second electrode 11 of the active LED chip 1a to be connected to a high level to control the active LED chip 1a to emit light.

[0118] In some embodiments, step S4, preparing the lower wiring layer 52 on the lower surface of the package 3, includes the following steps:

[0119] B1. For example Figure 16 As shown, the substrate 6 is removed, exposing the second electrode 11 of the effective LED chip 1 and the port electrode 20 of the control chip 2.

[0120] B2. For example Figure 17 As shown, a lower conductive line 520 is prepared on the lower surface of the package 3. The lower surface is the surface of the package 3 that exposes the second electrode 11 of the effective LED chip 1 and the port electrode 20 of the control chip 2.

[0121] B3. For example Figure 18 As shown, a lower insulating layer 521 is prepared on the lower surface of the package 3, and the lower insulating layer 521 covers the surface of the lower conductive line 520.

[0122] B4. For example Figure 19 As shown, port pads 40 are prepared on the surface of the lower insulating layer 521.

[0123] B5. For example Figure 20 As shown, a second metallized via 522 connected to the lower conductive line 520 and the port pad 40 is prepared on the surface of the lower insulating layer 521. It can be understood that the port pad 40 is electrically connected to the corresponding port electrode 20 of the control chip 2 through the second metallized via 522 passing through the lower insulating layer 521 and the lower conductive line 520 connected to the second metallized via 522.

[0124] In some embodiments, step S4, preparing the upper wiring layer 51 on the upper surface of the package 3, includes the following steps:

[0125] C1. For example Figure 21 As shown, an upper conductive line 510 and a first metallized via 50 connecting the upper conductive line 510 and the port pad 40 are prepared on the upper surface of the package 3. As mentioned above, the port pad 40 can be a power supply port pad 40a or a ground port pad 40d. The port pad 40 is connected through the first metallized via 50 so that the port pads of the LED package unit are all located on the same side, which facilitates connection with external circuits.

[0126] C2. For example Figure 15 As shown, an insulating layer 511 is prepared on the upper surface of the package 3, and the upper insulating layer 511 covers the surface of the conductive wire 510.

[0127] Optionally, the upper wiring layer 51 and the lower wiring layer 52 are fabricated using the RDL (rewiring layer) process.

[0128] In some embodiments, step S4 further includes the following step before fabricating the upper wiring layer 51: thinning the upper surface of the package 3 to expose the first electrode 10 of the LED chip 1. This ensures that the first electrode 10 of the effective LED chip 1 can be reliably electrically connected to the upper conductive line 510 during the fabrication of the upper wiring layer 51. Optionally, the initial thickness of the first electrode 10 (the thickness before thinning) is not less than 10 μm, so that after the thinning process, as many, or even all, of the first electrodes 10 of the effective LED chips 1a are reliably exposed, ensuring electrical connection with the upper conductive line 510.

[0129] The arrangement of the three connecting parts 5200 can be varied. In some embodiments, such as... Figure 1 and Figure 13As shown, the three connection portions 5200 are all located on the same side of the control chip 2 and are spaced apart along a first direction, which is parallel to the upper surface of the package 3. The projection of the upper conductive line 510 along the thickness direction of the package 3 simultaneously covers all the connection portions 5200. In other embodiments, such as Figure 22 As shown, the three connection portions 5200 are all located on the same side of the control chip 2. Two of the connection portions 5200 are spaced apart along the first direction, and the other connection portion 5200 is spaced apart from the two connection portions 5200 along the second direction. In this embodiment, since the distance between the different colored monochrome LED groups is relatively close, the light mixing effect can be improved. Similarly, the projection of the upper conductive line 510 along the thickness direction of the package 3 simultaneously covers all the connection portions 5200.

[0130] The first and second directions are perpendicular and both parallel to the upper surface of the package 3. Optionally, the package 3 is rectangular, and the first and second directions may correspond to the extension directions of the two sides of the LED package unit.

[0131] It is understandable that since the upper conductive line 510 does not need to be placed on the same surface as the lower conductive line 520, it occupies less radial space (referring to the direction perpendicular to the thickness direction of the package 3), and the volume of the LED package unit can be made smaller, which is beneficial to its miniaturization.

[0132] In some embodiments, the substrate 6 is glass, silicon wafer, ceramic, or a thin film. The material of the thin film may be, for example, polyimide (PI, Kapton), polyester film (PET, Mylar), polycarbonate (PC), or polyethylene terephthalate (PEN). The upper conductive line 510 and the lower conductive line 520 may be a metal conductive layer, ITO, or a metal mesh.

[0133] The upper insulating layer 520 is made of transparent material, and the upper conductive line 510 is also transparent. For example, it is made of transparent material or its line width and thickness are controlled so that light can pass through. In this way, the light of the LED chip 1 can be reliably emitted to the outside and observed by the human eye.

[0134] The package 3 can be made of transparent or opaque material. When made of opaque material, crosstalk between light rays can be reduced.

[0135] It is understood that in the illustrated embodiments, the size and position of each component (e.g., target area, LED chip, control chip, etc.) are illustrative. For example, when a smaller LED chip 1 is used, its thickness can be less than that of the control chip 2. In this case, a possible structural schematic diagram of an LED packaging unit is shown below. Figure 23As shown, the first electrode 10 of the effective LED chip 1a can be exposed by thinning a local area (at least corresponding to the target area) on the package 3, which facilitates the arrangement of the upper conductive line 510. Optionally, the outer surface of the upper insulating layer 511 is flat so that the insulating material in the area corresponding to the monochrome LED group is thicker, which is beneficial to improving the protection effect.

[0136] The present invention also proposes an LED packaging unit, which can be prepared by the LED packaging unit preparation method described above.

[0137] like Figure 5 As shown, the LED packaging unit includes a group of monochrome LEDs, a control chip 2, a package 3, an upper wiring layer 51, and a lower wiring layer 52.

[0138] like Figure 1 and Figure 2 As shown, the monochrome LED group includes multiple LED chips 1 that emit the same color light. Each LED chip 1 includes a first electrode 10 and a second electrode 11 located on both sides of it.

[0139] The control chip 2 includes multiple port electrodes 20. The positions and orientations of the LED chips 1 in the monochrome LED group are random. LED chips 1 whose second electrode 11 is located on the same plane as the port electrodes 20 are called effective LED chips 1a, and LED chips 1 whose second electrode 11 is not located on the same plane as the port electrodes 20 are called ineffective LED chips 1b. The control chip 2 is electrically connected to the second electrode 11 of the effective LED chips 1a.

[0140] Since the position and orientation of the LED chip 1 in the monochrome LED group are random, they can be formed by random distribution, which greatly reduces the positional accuracy requirements of the individual LED chip 1, helps to reduce the difficulty of the process, improve production efficiency, and reduce production costs.

[0141] The package 3 covers the control chip 2 and all the LED chips 1.

[0142] An upper wiring layer 51 is disposed on the upper surface of the package 3, and a lower wiring layer 52 is disposed on the lower surface of the package 3. The control chip 2 is electrically connected to the second electrode 11 of the active LED chip 1a through the lower wiring layer 52. Specifically, the upper wiring layer 51 includes an upper conductive line 510 and an upper insulating layer 511 covering the upper conductive line 510, and the lower wiring layer 52 includes a lower conductive line 520 and a lower insulating layer 521 covering the lower conductive line 520. The lower conductive line 520 connects the corresponding monochrome LED group and the corresponding port of the control chip 2.

[0143] like Figure 12 and Figure 13As shown, the port electrode 20 of the control chip 2 and the monochrome LED group are connected via a lower conductive line 520. The lower conductive line 520 connected to the monochrome LED group includes a connecting portion 5200, which carries the monochrome LED group. The monochrome LED group is located between the connecting portion 5200 and the upper conductive line 510. The first electrode 10 and the second electrode 11 of the active LED chip 1a are electrically connected to the upper conductive line 510 and the lower conductive line 520, respectively. The width of the connecting portion 5200 is increased to provide a larger area for connecting more LED chips 1.

[0144] In some embodiments, the lower wiring layer 52 includes a port assembly comprising a plurality of exposed port pads 40, which are electrically connected to the LED chip 1 and the control chip 2. Optionally, the port assembly includes a power supply port pad 40a, a first data port pad 40b, a second data port pad 40c, and a ground port pad 40d, each port pad being electrically connected to a corresponding port of the control chip 2 via a second metallized via 522 and a lower conductive line 520. The first electrode 10 of the LED chip 1 is electrically connected to either the power supply port pad 40a or the ground port pad 40d via an upper conductive line 510 and a first metallized via 50.

[0145] Optionally, all port pads 40 are exposed on the same surface of the LED package unit to facilitate the mounting of the LED package unit.

[0146] In some embodiments, the LED packaging unit includes three monochromatic LED groups, each having an LED chip 1 with a different emission color. For example, each group may include a first-color LED chip, a second-color LED chip, and a third-color LED chip. The first electrode 10 of the effective LED chip 1a of the three monochromatic LED groups is connected to the same upper conductive line 510 and the power supply port pad 40a or the ground port pad 40d to simplify the circuit.

[0147] Optionally, each group of monochrome LEDs includes at least two active LED chips 1a.

[0148] It is understood that other embodiments or structural details of the LED packaging unit can be found in the description above, and will not be repeated here.

[0149] It should be noted that, in the absence of conflict, the various embodiments described herein can be combined with each other to obtain more implementation schemes.

[0150] The above are merely specific embodiments of the present invention, and any improvements made based on the concept of the present invention shall be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating an LED packaging unit, characterized in that, Includes the following steps: S1. Provide a substrate (6), an LED chip (1) and a control chip (2), wherein the LED chip (1) includes an electrode pair, the electrode pair including a first electrode (10) and a second electrode (11) located on opposite sides of the LED chip (1). S2. The control chip (2) is placed on the first surface (60) of the substrate (6), and the port electrode (20) of the control chip (2) is in contact with the first surface (60). Multiple LED chips (1) with the same emitting color are randomly scattered in the same target area (61), and effective LED chips (1a) with the second electrode (11) in contact with the first surface (60) and ineffective LED chips (1b) with the second electrode (11) not in contact with the first surface (60) are randomly formed. Multiple LED chips (1) located in the same target area (61) constitute a monochrome LED group. S3. An encapsulation (3) covering the control chip (2) and all the LED chips (1) is provided on the outside of the substrate (6). S4. A lower wiring layer (52) is prepared on the lower surface of the package (3), and an upper wiring layer (51) is prepared on the upper surface of the package (3).

2. The method for preparing the LED packaging unit as described in claim 1, characterized in that, The LED chip (1) is divided into a first-color LED chip, a second-color LED chip and a third-color LED chip according to its light emission color. In step S2, three monochrome LED groups are formed.

3. The method for preparing the LED packaging unit as described in claim 1, characterized in that, In step S2, the number of LED chips (1) contained in the monochrome LED group is not less than 8.

4. The method for preparing the LED packaging unit as described in claim 1, characterized in that, In step S2, the step of randomly scattering multiple LED chips (1) with the same emitting color in the same target area (61) includes: pouring multiple LED chips (1) with the same emitting color into the target area (61).

5. The method for preparing the LED packaging unit as described in claim 1, characterized in that, In step S2, the step of randomly distributing multiple LED chips (1) of the same emission color in the same target area (61) includes the following steps: Multiple LED chips (1) with the same emitting color are placed in a liquid to form an LED paste; The LED paste is transferred to the target area (61).

6. The method for preparing the LED packaging unit as described in claim 5, characterized in that, The LED paste is transferred to the target area (61) by means of screen printing, embossing, spraying or printing.

7. The method for preparing the LED packaging unit as described in claim 1, characterized in that, In step S4, the preparation of the lower wiring layer (52) on the lower surface of the package (3) includes the following steps: Remove the substrate (6) to expose the second electrode (11) of the effective LED chip (1a) and the port electrode (20) of the control chip (2). A lower conductive line (520) is prepared on the lower surface of the package (3), the lower surface being the surface of the package (3) that exposes the second electrode (11) of the effective LED chip (1a) and the port electrode (20) of the control chip (2); A lower insulating layer (521) is prepared on the lower surface and the lower insulating layer (521) covers the surface of the lower conductive line (520); Port pads (40) are prepared on the surface of the lower insulating layer (521); A second metallized via (522) is prepared to communicate with the lower conductive line (520) and the port pad (40).

8. The method for preparing the LED packaging unit as described in claim 7, characterized in that, In step S4, the fabrication of the upper wiring layer (51) on the upper surface of the package (3) includes the following steps: An upper conductive line (510) and a first metallized via (50) connecting the upper conductive line (510) and the port pad (40) are prepared on the upper surface of the package (3). An upper insulating layer (511) is prepared on the upper surface of the package (3) and the upper insulating layer (511) covers the surface of the upper conductive line (510).

9. The method for preparing the LED packaging unit as described in claim 8, characterized in that, In step S4, before preparing the upper wiring layer (51), the following steps are also included: thinning the upper surface of the package (3) to expose the first electrode (10) of the LED chip (1), wherein the initial thickness of the first electrode 10 is not less than 10 μm.

10. The method for preparing an LED packaging unit according to any one of claims 1 to 9, characterized in that, The center of gravity of the LED chip (1) is close to the second electrode (11). The LED chip (1) includes a metal mass block connected to its second electrode (11); and / or, The cross-sectional area of ​​the end where the second electrode (11) of the LED chip (1) is located is greater than the cross-sectional area of ​​the end where the first electrode (10) is located.

11. The method for preparing an LED packaging unit according to any one of claims 1 to 9, characterized in that, The LED chip (1) is in the shape of a cuboid or a cube; The LED chip (1) includes two sets of electrode pairs, and the second electrodes (11) of the two sets of electrode pairs are located on two adjacent surfaces of the LED chip (1); or, The LED chip (1) includes three sets of electrode pairs, and the second electrodes (11) of the three sets of electrode pairs are located on three adjacent surfaces of the LED chip (1).

12. An LED packaging unit, characterized in that, include: A monochrome LED group includes multiple LED chips (1) that emit the same color light. Each LED chip (1) includes a first electrode (10) and a second electrode (11) located on both sides of it. The control chip (2) includes multiple port electrodes (20). The position and orientation of the LED chips (1) of the monochrome LED group are random. The LED chip (1) whose second electrode (11) is located on the same plane as the port electrode (20) is called a valid LED chip (1a). The LED chip (1) whose second electrode (11) is not located on the same plane as the port electrode (20) is called an invalid LED chip (1b). The package (3) covers the outside of the control chip (2) and all the LED chips (1); An upper wiring layer (51) is disposed on the upper surface of the package (3); as well as, The lower wiring layer (52) is disposed on the lower surface of the package (3), and the control chip (2) is electrically connected to the second electrode (11) of the effective LED chip (1a) through the lower wiring layer (52).

13. The LED packaging unit as described in claim 12, characterized in that, The lower wiring layer (52) includes a port assembly, which includes a plurality of exposed port pads (40) and is electrically connected to the LED chip (1) and the control chip (2).

14. The LED packaging unit as described in claim 13, characterized in that, The port assembly includes a power supply port pad (40a) and a ground port pad (40d). The power supply port pad (40a) and the grounding port pad (40d) are both electrically connected to the control chip (2); The active LED chip (1a) is electrically connected to the power supply port pad (40a) or the grounding port pad (40d).

15. The LED packaging unit as described in claim 14, characterized in that, All of the port pads (40) are exposed on the same surface of the LED package unit. The upper wiring layer (51) includes an upper conductive line (510) electrically connected to the first electrode (10) of the active LED chip (1a) and an upper insulating layer (511) covering the upper conductive line (510). The upper conductive line (510) and the power supply port pad (40a) or the ground port pad (40d) are connected through a first metallized via (50) through the package body (3).

16. The LED packaging unit as described in claim 15, characterized in that, It includes three monochromatic LED groups, each of which has an LED chip (1) with a different emitting color. The first electrode (10) of the effective LED chip (1a) of the three monochromatic LED groups is connected to the power supply port pad (40a) or the ground port pad (40d) through the same upper conductive line (510).

17. The LED packaging unit according to any one of claims 12 to 16, characterized in that, The lower wiring layer (52) includes a lower conductive line (520) and a lower insulating layer (521) covering the lower conductive line (520). Each port pad (40) and the control chip (2) are connected through a second metallized via (522) passing through the lower insulating layer (521) and the lower conductive line (520). The port electrode (20) of the control chip (2) and the monochrome LED group are connected by a lower conductive line (520).

18. The LED packaging unit as described in claim 17, characterized in that, The lower conductive line (520) connected to the monochrome LED group has a widened connection portion (5200), on which the LED chip (1) of the monochrome LED group is located.

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