TOP type LED display panel and TOP type LED display screen

Abstract

The invention discloses a TOP type LED display panel and a TOP type LED display screen, and relates to the technical field of display. The TOP type LED display panel comprises a circuit board, at least one LED lamp bead and a welding material, the circuit board comprises a substrate and at least one bonding pad group, the at least one bonding pad group is arranged on the first surface of the substrate, and each bonding pad group comprises at least two bonding pads; each LED lamp bead is connected to one bonding pad group, each LED lamp bead comprises at least two lamp bead pins, and each lamp bead pin is connected to one bonding pad; the welding material is arranged between the lamp bead pin and the bonding pad; the orthographic projection of each lamp bead pin on each substrate is located within the orthographic projection of the bonding pad on the substrate. According to the Top type LED display screen, the yin-yang color can be effectively improved, the risk of falling of the bonding pad due to light collision can be reduced, the comprehensive performance of the TOP type LED display screen can be improved, and the cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of display technology, specifically relating to a TOP type LED display panel and a TOP type LED display screen. Background Technology

[0002] With the development of light-emitting diodes (LEDs), top-type LED displays have become increasingly popular due to their high production efficiency, wide viewing angle, and good reliability, making them suitable for diverse display scenarios and attracting more and more extensive research and application.

[0003] In current top-mount LED displays, after the surface mount technology (SMT) process is completed, the LEDs on one side of the circuit board in the top-mount LED display panel often tilt, causing a change in the light emission angle of the LEDs. This results in uneven color reproduction and poor display quality. Furthermore, top-mount LED displays are inevitably subject to impacts during assembly, disassembly, and transportation. Impacts can cause the solder pads connecting the LEDs to the LEDs to detach, leading to solder pad loss. This problem is difficult to repair, significantly increasing the cost of top-mount LED displays in addition to their poor display quality, hindering industrial production and application. Summary of the Invention

[0004] The purpose of this application is to overcome the above-mentioned shortcomings of the prior art and provide a TOP type LED display panel and a TOP type LED display screen to solve the problems of LED beads tilting and some pads falling off during LED bead collisions in existing TOP type LED display panels. This ensures that the TOP type LED display screen can effectively improve color balance and reduce the risk of pads falling off due to LED collisions, thereby improving the overall performance of the TOP type LED display screen and reducing costs.

[0005] To achieve the aforementioned objectives, a first aspect of this application provides a TOP-type LED display panel, comprising:

[0006] A circuit board, the circuit board including a substrate and at least one pad group, the at least one pad group being disposed on a first surface of the substrate, each pad group including at least two pads;

[0007] At least one LED bead, each LED bead being connected to one of the pad groups, each LED bead including at least two bead pins, each bead pin being connected to one of the pads;

[0008] Welding material, wherein the welding material is disposed between the lamp bead pin and the solder pad;

[0009] Wherein, the orthographic projection of each of the lamp bead pins on each of the substrates is located within the orthographic projection of the pad on the substrate.

[0010] In some embodiments, the orthographic projection of the periphery of each of the LED pins onto the substrate lies within the orthographic projection of the boundary of the pad onto the substrate.

[0011] Each LED chip includes four chip pins, each pad group includes four pads, and the perimeter of each chip pin is set within the perimeter of its corresponding pad.

[0012] In some embodiments, the length of each LED pin in each LED chip along the first direction is A, the width of each LED pin in each LED chip along the second direction is B, the distance between any two adjacent LED pins in each LED chip along the first direction is D, and the distance between any two adjacent LED pins in each LED chip along the second direction is C.

[0013] The length of each pad in each pad group along the first direction is A1, the width of each pad in each pad group along the second direction is B1, the distance between any two adjacent pads in each pad group along the first direction is D1, and the distance between any two adjacent pads in each pad group along the second direction is C1.

[0014] Where, A1=A+(0.12~0.18)mm, B1=B+(0.08~0.12)mm, C1=C-(0.05~0.10)mm, D1=D-(0.08~0.15)mm.

[0015] In some embodiments, the orthographic projection of the solder material on the substrate is partially offset from the orthographic projection of each of the LED pins on the substrate, and the orthographic projection of the solder material on the substrate is offset to the right relative to the orthographic projection of each of the LED pins on the substrate.

[0016] In some embodiments, the orthographic projection of the solder material on the substrate is partially offset from the orthographic projection of each of the LED pins on the substrate, and the orthographic projection of the solder material on the substrate is offset to the left relative to the orthographic projection of each of the LED pins on the substrate.

[0017] In some implementations, A1 = A + (0.15~0.18) mm, B1 = B + (0.1~0.12) mm, C1 = C - (0.08~0.10) mm, and D1 = D - (0.12~0.15) mm.

[0018] In some embodiments, the circuit board further includes a surface solder resist layer covering the substrate, and the surface solder resist layer has a plurality of discrete and spaced grooves, with each of the solder pads disposed in one of the grooves;

[0019] Along the second direction, the height of the pad is less than the height of the surface solder mask around the groove;

[0020] And / or, the surface solder resist layer is achieved by surface treatment methods such as nickel-gold plating, tin plating, or forming an organic solder resist film on the surface of the solder pad.

[0021] In some embodiments, the substrate includes a glass fiber layer, and the pads are pressed onto the surface of the glass fiber layer and are tightly bonded to the glass fiber layer;

[0022] And / or,

[0023] The pad material includes any one of pure copper, pure copper plated with nickel gold, or pure copper plated with tin.

[0024] In some embodiments, each LED chip further includes an LED chip, bonding wires, a packaging layer, and a chip package. The LED chip is disposed on the side of the chip pin facing away from the pad, and the LED chip is connected to the chip pin via the bonding wires. The packaging layer is used to encapsulate the LED chip, the bonding wires, and a portion of the chip pins. The LED chip, the bonding wires, a portion of the chip pins, and the packaging layer are all integrated in the surface-mount chip package, and the remaining portion of the chip pins are exposed from the chip package and soldered to the pad via the soldering material.

[0025] A second aspect of this application provides a TOP-type LED display screen, including the aforementioned TOP-type LED display panel.

[0026] Compared with the prior art, this application has the following technical effects:

[0027] The TOP-type LED display panel and TOP-type LED display screen provided in this application have optimized the pad design, proposing a new design that combines the pad and LED chip pins. By setting a certain tolerance space for all LED chip pins in their corresponding pads, this structure of the TOP-type LED chip with its inner bent pins allows the LED chip pins to move within the tolerance space of the pads, reducing the risk of LED chip tilting caused by different contact areas between the LED chip pins and the soldering material during the soldering process. This also improves the color temperature variation problem of the TOP-type LED display panel, thus ensuring compatibility with... The various objective tolerances present in the manufacturing of TOP-type LED display panels improve the user experience. On the other hand, when an LED bead is impacted, the force is no longer applied from the edge of the solder pad, but rather the point of force moves to the inside of the solder pad, where the solder material is the first to be subjected to force and tear, thus improving the defect of tearing from the edge of the solder pad when the LED is impacted. This reduces the risk of the solder pad falling off when the LED is bumped, improving reliability. In addition, even after a severe impact, only the solder material of the LED bead pin breaks while the solder pad remains intact. In this case, only the LED bead needs to be replaced, greatly reducing the difficulty and cost of maintenance. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram illustrating the positional relationship between LED beads and a circuit board, provided by related technologies.

[0030] Figure 2 This is another schematic diagram showing the positional relationship between LED beads and the circuit board provided by related technologies;

[0031] Figure 3 This is a schematic diagram of the structure of a TOP type LED display screen provided in an embodiment of this application;

[0032] Figure 4 This is a schematic diagram showing the welding material deflected to the right in a TOP-type LED display screen according to an embodiment of this application;

[0033] Figure 5 This is a schematic diagram showing the welding material deflected to the left in a TOP-type LED display screen according to an embodiment of this application;

[0034] Figure 6This is a schematic diagram of the LED bead offset in a TOP type LED display screen provided in an embodiment of this application;

[0035] Figure 7 This is a schematic diagram of a TOP-type LED display screen with torn solder joints and intact solder pads, provided in an embodiment of this application.

[0036] Figure 8 This is a schematic diagram of the solder pads and the surface solder resist layer in the circuit board of a TOP type LED display provided in an embodiment of this application;

[0037] Figure 9 This is a top view showing the positional relationship between the substrate, pads, and LED beads in a TOP-type LED display screen provided in this application embodiment;

[0038] Figure 10 This is a top view of an LED bead in a TOP-type LED display screen provided in an embodiment of this application;

[0039] Figure 11 This is a top view of the pads in a TOP-type LED display screen provided in an embodiment of this application. Detailed Implementation

[0040] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0042] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0043] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0044] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0045] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a known unit of mass such as μg, mg, g, or kg.

[0046] The terms "first," "second," etc., are used for descriptive purposes only to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0047] With the development of technology, LED displays have received increasingly widespread research and application due to their advantages such as high contrast and wide color gamut, high brightness and wide viewing angle, high refresh rate and low latency. At the same time, LED displays are constantly improving and being perfected, leading to increasingly higher demands on their display effects.

[0048] There are many types of LED displays, and Top-mount LED displays are one of them. Top-mount LED displays use TOPLEDs (Surface Mount Devices, or SMD LEDs) as their core component. Their advantages include high production efficiency, wide viewing angle, and good reliability, making them suitable for diverse display scenarios. Specifically, due to their high brightness, high contrast, and wide viewing angle, Top-mount LED displays can be widely used in indoor commercial displays, outdoor advertising, and stage backdrops. Furthermore, the SMD packaging characteristics allow for smaller pixel pitches, making them suitable for control rooms and conference centers with high resolution requirements.

[0049] In traditional top-mount LED displays, after the surface mount technology (SMT) process is completed, the LEDs on one side of the circuit board often tilt, causing a change in the light-emitting angle of the LEDs. This results in a color imbalance problem across the entire top-mount LED display, leading to poor display quality. It's important to note that the tilt of the LEDs causes a change in their light-emitting angle, resulting in differences in brightness at different viewing angles. This manifests as noticeable color or brightness differences in different areas of the top-mount LED display; for example, an abnormal area may appear brighter from the left viewing angle and darker from the right viewing angle. This is known as color imbalance.

[0050] The aforementioned tilting of LED beads is closely related to various factors, including circuit board consistency, LED bead pin consistency, solder material printing consistency, and LED bead mounting consistency. Furthermore, in actual manufacturing processes, unavoidable tolerances exist in materials, processes, and equipment. Therefore, to ensure consistent display effects for top-type LED displays, it's advisable to improve the fault tolerance of the LED beads and the solder pads on the circuit board. This reduces the impact of objective factors during production, manufacturing, and transportation on the display effect of top-type LED displays. In addition, top-type LED displays inevitably experience bumps and knocks during assembly, disassembly, and transportation. After impact, some solder pads connected to the LED beads may detach, a problem that is often difficult to repair. Therefore, besides the poor display effect caused by the top-type design, it also significantly increases costs, hindering industrial production and application.

[0051] In view of the above problems, the LED beads and pads in the Top-type LED display can be designed to effectively improve the color imbalance problem and reduce the risk of pads falling off due to light collision.

[0052] Currently, there are various methods used in the design of LED chips and pads, for example, Figure 1 This illustrates a single-sided limiting method for the inner limiting of the circuit board 1 and the LED bead 2 in a related art. Figure 1 This illustrates a single-sided limiting method for the outer limiting of the circuit board 1 and the LED bead 2 in a related art. It should be noted that... Figure 1 and Figure 2 The dotted lines in the diagram have no practical meaning; they are only there to indicate the limit. In practical applications, Figure 1 and Figure 2 The pads in circuit board 1 ( Figure 1 and Figure 2 (As shown in the image) There are differences in expansion and contraction, and mark points. During the SMT process, the center of the solder pad will deviate from the surface mount coordinates of LED 2. During reflow soldering, the LED pins in LED 2 ( Figure 1 and Figure 2 (As shown in the diagram) Uneven force can cause LED beads 2 to tilt. For example, when the circuit board shrinks, the LED bead leads on both sides will shift outwards after being mounted, causing the leads on both sides to tilt inwards. The left pad of the circuit board will shift to the right relative to the LED bead leads, causing the LED bead to tilt to the right after soldering. It should be noted that circuit board expansion and contraction refers to the changes in the overall size of the circuit board after the integrated circuit (IC) components are mounted and reflow soldered. The expansion and contraction of each circuit board is different, resulting in the circuit board becoming larger or smaller. This can cause the stencil for printing solder paste or the pick-and-place machine to misalign the points when mounting each LED bead during the subsequent production of LED beads.

[0053] Furthermore, the display effect of Top-type LED displays is affected by various tolerances, including those related to circuit board materials, LED chip pins, soldering material printing, LED chip mounting, fixture deformation, stencil fabrication tolerances, and printing machine precision. These factors can all cause soldering material printing to shift. Once the soldering material shifts, it will cause uneven force on the LED chip pins during reflow soldering, resulting in tilting. Specifically, when the soldering material printing is biased to the right, the bottom of the right LED chip pin lacks soldering material, while the bottom of the left LED chip pin is full of soldering material. During soldering, the contact area between the left and right LED chip pins and the soldering material is different, leading to a difference in wetting force. The right LED chip pin climbs the soldering material first in the vertical direction, generating downward wetting pull earlier, resulting in a solder joint where the left LED chip is higher than the right, and vice versa. Alternatively, when the LED chip pin is biased to the left, the bottom of the left LED chip pin lacks soldering material, while the bottom of the right LED chip pin is full of soldering material, resulting in a solder joint where the left LED chip is lower than the right, and vice versa.

[0054] Furthermore, when existing pads are soldered to LED chips, the LED chip leads on both sides are soldered flush with the outer or inner side of the pads. Therefore, when the LED chip is impacted, the force is applied from the edge of the pad to tear it. This means that the impact on the LED chip can cause the tearing force point to be at the very edge of the pad. This can easily lead to the LED chip peeling off from the pad, causing the pad to fall off. The LED chip cannot be repaired properly, making maintenance difficult or even causing it to be scrapped, which greatly increases maintenance costs.

[0055] Example 1

[0056] Based on the above, this application provides a TOP-type LED display panel. (See reference...) Figures 3 to 11 As shown, the TOP-type LED display panel provided in this application embodiment may include: a circuit board 1, at least one LED bead and soldering material 3. The circuit board 1 includes a substrate 11 and at least one pad group. The at least one pad group is disposed on the first surface m1 of the substrate 11. Each pad group includes at least two pads 12. Each LED bead is connected to a pad group. Each LED bead includes at least two bead pins 21. Each bead pin 21 is connected to a pad 12. Soldering material 3 is disposed between the bead pins 21 and the pads 12.

[0057] In this case, the orthographic projection E1 of each lamp bead pin 21 on the substrate 11 is located within the orthographic projection E12 of each corresponding pad 12 on the substrate 11.

[0058] In practical applications, the aforementioned circuit board 1 can be a printed circuit board (PCB), etc.

[0059] In the case of multiple pad groups in the embodiments of this application, the number, structure, size, etc. of the pads included in each of the multiple pad groups may be the same or different, and no specific limitation is made here.

[0060] Furthermore, when each pad group includes multiple pads 12, the structure, size, etc. of the multiple pads can be the same or different, and no specific limitation is made here.

[0061] It should be understood that the orthographic projection E21 of each LED pin 21 on the circuit board 1 being within the orthographic projection E12 of its corresponding pad 12 on the circuit board 1 means that each pad 12 has a tolerance space reserved outside each corresponding LED pin 21, allowing the LED pin 21 to move within this tolerance space. Specifically, each pad 12 has a tolerance space reserved around its four outer edges outside each corresponding LED pin 21, allowing the LED pin 21 to move within this tolerance space. For example, each LED may include four LED pins 21, and the pad group may include four pads 12, each pad 12 having a tolerance space to accommodate each LED pin 21. Figure 3 Two LED pins 21 are shown. The orthographic projection E21 of one LED pin 21 on the circuit board 1 is located within the orthographic projection E12 of a pad 12 on the circuit board 1. The orthographic projection E21 of the other LED pin 21 on the circuit board 1 is also located within the orthographic projection E12 of a pad 12 on the circuit board 1. The other two LED pins and their orthographic projections are not shown.

[0062] In practical applications, the aforementioned welding material 3 may include solder, specifically solder paste, etc. Thus, the solder paste is disposed between each LED bead pin 21 and the pad 12, for soldering each LED bead pin 21 to a pad 12, thereby enabling at least one pad group to be soldered to the first surface m1 of the substrate 11.

[0063] The TOP-type LED display adopts a PLCC structure, which integrates LED chips, bonding wires, lamp bead pins, and packaging layers into a single surface-mount lamp bead package. This design allows LED beads to be directly and batch-mounted onto the circuit board pads via reflow soldering, significantly improving production efficiency and consistency. The TOP-type LED display emits light perpendicular to the first surface of the substrate 11 on the circuit board, meaning it emits light from the top.

[0064] The TOP-type LED display panel provided in this application embodiment ensures that the orthogonal projection of all LED chip pins on the substrate is within the orthogonal projection of their corresponding pads on the substrate. This, on the one hand, allows for reference... Figures 4 to 7 As shown, whether it's the offset of the soldering material printing or the offset of the LED chip, the LED chip leads can move within the tolerance space of the pad. This ensures that the LED chip leads on both sides are fully soldered after soldering. The increased tolerance of the pad reduces the risk of LED chip tilting due to different contact areas between the LED chip leads and the soldering material during soldering, thus improving the color temperature variation problem of TOP-type LED display panels. On the other hand, due to the enlarged pad and increased adhesion, and the pre-reserved tolerance space on the outside of the LED chip leads, when the LED chip is impacted, the force is no longer applied from the edge of the pad. Instead, the point of force changes, moving to the inside of the pad. The soldering material is the first to be subjected to force and tearing, thus reducing the risk of the pad falling off and protecting it from detachment. Even after a severe impact, only the soldering material on the LED chip leads breaks while the pad remains intact. In this case, only the LED chip needs to be replaced, greatly reducing repair difficulty and cost, which is beneficial for industrial production and application.

[0065] Therefore, the TOP type LED display panel provided in this application provides a tolerance space for each pad pin in the pad design according to the size of the lamp bead pin. That is, the pad is extended to a certain size around the lamp bead pin. This TOP type LED lamp bead has a new lamp bead pin and pad structure with the inner bending of the lamp bead pin, which makes the TOP type LED display better and suitable for outdoor and indoor use scenarios.

[0066] Finally, it should be noted that... Figure 7 The dotted line in the image represents point 4 where the solder pad is torn and subjected to force. The impact force is F, and the direction is as shown by the arrow.

[0067] In some implementations, reference Figure 10 As shown, in the TOP-type LED display panel provided in this application embodiment, the specifications of each LED pin 21 can be set as follows: each LED pin 21 along the first direction ( Figure 10 The length of the pin 21 in the second direction (ox direction) is A, and each LED pin 21 is along the second direction (ox direction) Figure 10 The length of the LED pin 21 in the oy direction is B, the distance between any two adjacent LED pins 21 in the oy direction is C, and the distance between any two adjacent LED pins 21 in the ox direction is D.

[0068] At the same time, refer to Figure 11As shown, the specifications of the pads 12 in each pad group can be set as follows: the length of each pad 12 along the ox direction is A1, the width of each pad 12 along the oy direction is B1, the distance between any two adjacent pads 12 along the oy direction is C1, and the distance between any two adjacent pads 12 along the ox direction is D1.

[0069] Where, A1=A+(0.12~0.18)mm, B1=B+(0.08~0.12)mm, C1=C-(0.05~0.10)mm, D1=D-(0.08~0.15)mm.

[0070] Therefore, the sum of the width of any two adjacent LED pins 21 along the oy direction and the distance between these two LED pins 21 along the oy direction is W, and the sum of the length of any two adjacent LED pins 21 along the ox direction and the distance between these two LED pins 21 along the ox direction is L, that is, 2B+C=W, 2A+D=L.

[0071] Therefore, the sum of the width of any two adjacent pads 12 along the oy direction and the distance between these two pads 12 along the oy direction is W1, and the sum of the length of any two adjacent pads 12 along the ox direction and the distance between these two pads 12 along the ox direction is L1, that is, 2B1+C1=W1, 2A1+D1=L1.

[0072] The TOP-type LED display panel provided in this application embodiment, according to the specifications of the LED chip pins, sets them in a pad. The pad design provides a certain tolerance space for the corresponding LED chip pins, meaning the pad compensates for this tolerance space around the chip pins. This ensures that during the SMT process, regardless of whether solder material or LED chip misalignment occurs, all chip pins, pads, and solder material are matched, guaranteeing good soldering at the bottom of the chip pins and near-balanced force on the left and right chip pins. This improves LED chip tilt and reduces the color distortion problem of the TOP-type LED display panel. Furthermore, after surface mounting, when an LED chip is impacted, the force is no longer torn from the edge of the pad; the force point shifts to the inside of the pad, reducing the risk of the pad falling off. Even after a severe impact, only the solder material of the chip pins breaks, while the pad remains intact. In this case, only the LED chip needs to be replaced, greatly reducing repair difficulty and cost, which is beneficial for industrial production and application.

[0073] In some implementations, reference Figure 4 As shown, the orthographic projection E3 of the welding material 3 on the substrate 11 is partially offset from the orthographic projection E21 of each lamp bead pin 21 on the substrate 11, and the orthographic projection E3 of the welding material 3 on the substrate is offset to the right relative to the orthographic projection E21 of each lamp bead pin 21 on the substrate.

[0074] Or, refer to Figure 5 As shown, the orthographic projection E3 of the welding material 3 on the substrate 11 is partially offset from the orthographic projection E21 of each lamp bead pin 21 on the substrate 11, and the orthographic projection E3 of the welding material 3 on the substrate is offset to the left relative to the orthographic projection E21 of each lamp bead pin 21 on the substrate.

[0075] exist Figure 4 and Figure 5 Medium: A1=A+(0.15~0.18)mm, B1=B+(0.1~0.12)mm, C1=C-(0.08~0.10)mm, D1=D-(0.12~0.15)mm.

[0076] It should be noted that, as Figure 6 As shown, the LED bead can also be offset relative to the welding material 3. Specifically, the LED bead can be offset to the left or to the right relative to the welding material 3. When the LED bead is offset to the left relative to the welding material 3, it can also be regarded as the welding material 3 being offset to the right relative to the LED bead. And when the LED bead is offset to the right relative to the welding material 3, it can also be regarded as the welding material 3 being offset to the left relative to the LED bead.

[0077] exist Figure 6 Medium: A1=A+(0.12~0.15)mm, B1=B+(0.08~0.1)mm, C1=C-(0.05~0.08)mm, D1=D-(0.08~0.12)mm.

[0078] The TOP-type LED display panel provided in this application embodiment, even if each LED pin and its corresponding solder material are misaligned due to various reasons, such as the solder material shifting left or right relative to each LED pin, can still ensure that the LED pin, solder pad, and solder material are matched, given that the pad design provides a certain tolerance space for the corresponding LED pin. This ensures that the LED pin, solder pad, and solder material are well-soldered at the bottom of the LED pin and that the forces on the left and right LED pins are nearly balanced, which can improve the tilting of the LED and reduce the color imbalance problem of the TOP-type LED display panel. On the other hand, after the LED is mounted, when it is impacted, the force is no longer torn from the edge of the solder pad, but the force point is transferred to the inside of the solder pad, thereby reducing the risk of the solder pad falling off. Even after a severe collision, only the solder material of the LED pin will break, but the solder pad will remain intact. In this case, only one LED can be replaced, which greatly reduces the difficulty and cost of maintenance and is beneficial to industrial production and application.

[0079] In some implementations, reference Figure 3 and Figure 8As shown, in the TOP type LED display panel provided in this application embodiment, the circuit board 1 may include a substrate 11 and a surface solder resist layer 13. The surface solder resist layer 13 covers the substrate 11 and has a plurality of discrete and spaced grooves K1. Each pad 12 is disposed in a groove K1. Along the oy direction, the height of the pad 12 is less than the height of the surface solder resist layer 13 around the groove K1.

[0080] In practical applications, the substrate 11 may include a glass fiber layer, and the pads 12 are pressed onto the surface of the glass fiber layer and are tightly bonded to the glass fiber layer.

[0081] The material of the solder pad 12 can be any one of pure copper, pure copper plated with nickel gold, or pure copper plated with tin. The solder pad 12 can be used to solder LED chips and provide a channel for transmitting electrical signals to the LED chips.

[0082] In practical applications, the aforementioned surface solder mask layer 13 can be achieved through surface treatment methods such as nickel-gold plating, tin plating, or forming organic solderability preservatives (OSP). Specifically, the surface solder mask layer 13 can cover the glass fiber layer and the edge of the pad 12. The area of ​​the pad 12 not covered by the surface solder mask layer 13 is the area of ​​the soldering material 3, such as solder. The surface solder mask layer 13 enables the solder to be confined to the exposed area of ​​the pad 12 during the melting process and prevents it from flowing around. Therefore, the solder can be uniformly confined in the area of ​​the pad 12. At the same time, the surface solder mask layer 13 covers part of the edge of the pad 12, which can further improve the adhesion of the pad 12.

[0083] The surface solder resist layer 13 is typically composed of a photosensitive resin material and can be retained in specific areas through processes such as printing and photocuring, photolithography, and inkjet printing. Openings are only left in the pad areas to facilitate soldering, thus preventing solder bridging and short circuits during soldering. Simultaneously, it isolates the conductive layer in the substrate from the external environment, avoiding oxidation and physical damage, and enhances the substrate's scratch and abrasion resistance. The surface solder resist layer material can be selected from green solder mask, white solder mask, black solder mask, etc.

[0084] Among them, the groove K1 in the surface solder mask layer can utilize the "photocuring" property of the photosensitive resin material to selectively remove the surface solder mask layer of the pad area through exposure and development; or, the photosensitive resin material can be selectively printed out by a "screen", and the area where the photosensitive resin material is not printed out is the opening, which is not specifically limited here.

[0085] refer to Figure 8 As shown, along the oy direction, the height of the surface solder mask layer 13 around the groove K1 is greater than the height of the pad 12 by W1.

[0086] The TOP-type LED display panel provided in this application embodiment has a pad height in the second direction that is lower than the surface solder mask height in the second direction. That is, the pad is recessed relative to the surface solder mask on the substrate surface. This allows the pad to provide a certain tolerance space for the LED chip pins, while also ensuring that the LED chip pins have a certain distance from the surface of the circuit board in the second direction. This better ensures that all LED chip pins, pads, and soldering materials are matched during the SMT process, further improving LED chip tilt and reducing the color imbalance problem of the TOP-type LED display panel. On the other hand, after mounting, when the LED chip is impacted, the risk of the pad falling off is further reduced, greatly reducing the difficulty and cost of maintenance, which is beneficial for industrial production and application.

[0087] In some implementations, reference Figure 3 As shown, in the TOP-type LED display panel provided in this application embodiment, each LED bead also includes an LED chip 22, a bonding wire 23, a packaging layer 24, and a bead package 25. The LED chip 22 is disposed on the side of the bead pin 21 away from the pad 12, and the LED chip 22 is connected to the bead pin 21 through the bonding wire 23. The packaging layer 24 is used to encapsulate the LED chip 22, the bonding wire 23, and part of the bead pin 21. The LED chip 22, the bonding wire 23, part of the bead pin 21, and the packaging layer 24 are all integrated in the surface-mount bead package 25, and the remaining part of the bead pin 21 is exposed from the bead package 25 and soldered to the pad 12 through the soldering material 3.

[0088] In practical applications, LED chip 22 may include red LED chip 221, green LED chip 222, and blue LED chip 223. Red LED chip 221, green LED chip 222, and blue LED chip 223 can form an RGB chip, which can be connected to the LED bead pin 21 through at least one bonding wire 23.

[0089] The encapsulation layer 24 can be encapsulating adhesive, which is used to encapsulate the RGB chip, bonding wire 23 and some LED pins 21, thus protecting these structures from external corrosion.

[0090] The LED chip package 25 can be a plastic encapsulation body, which is used to completely wrap the upper half of the entire LED chip and expose a portion of the chip pins 21 in the lower half, which can be used for soldering.

[0091] In practical applications, LED beads are interconnected with circuit boards by soldering materials, such as solder, to bond the LED bead pins 21 to the pads 12. The process for achieving this structure can be as follows: First, solder paste is printed on the pads using a printer; then, the LED beads are mounted onto the pads 12 of the substrate with the printed solder paste using a pick-and-place machine; finally, the solder paste is melted by reflow soldering to form solder, thus completing the soldering of the LED beads.

[0092] The TOP-type LED display panel provided in this application optimizes the pad design by proposing a new design that combines pads and LED chip pins. By providing a certain tolerance space for all LED chip pins within their corresponding pads, this structure of the TOP-type LED chip's inner bent pins allows the pins to move within the tolerance space of the pads. This reduces the risk of LED chip tilting due to uneven contact areas between the pins and the soldering material during soldering, improving the color balance issue of the TOP-type LED display panel. It also accommodates various objective tolerances present in the manufacturing of TOP-type LED display panels, enhancing the user experience. Furthermore, when an LED chip is impacted, the force is no longer applied from the edge of the pad; instead, the force point moves to the inside of the pad, prioritizing the soldering material for breakage. This improves upon the defect of tearing from the pad edge during impact, reducing the risk of pad breakage and increasing reliability. Even after a severe impact, only the soldering material of the LED chip pins breaks while the pad remains intact, allowing for the replacement of only one LED chip, significantly reducing repair difficulty and cost.

[0093] Example 2

[0094] This application provides a TOP type LED display screen, which may include the TOP type LED display panel in Embodiment 1.

[0095] This application provides a TOP-type LED display screen, which optimizes the pad design by proposing a new pad and LED pin combination design. By setting a certain tolerance space for all LED pins in each LED within their corresponding pad, this TOP-type LED pin structure with its inner bent pins allows the LED pins to move within the tolerance space of the pad, reducing the risk of LED tilting caused by different contact areas between the LED pins and the soldering material during soldering. This also improves the color temperature variation problem of the TOP-type LED display screen, thus compatibility with multiple issues present in the manufacturing of TOP-type LED displays. On the one hand, it improves the objective tolerance and enhances the user experience; on the other hand, when the LED bead is impacted, the force is no longer applied from the edge of the pad, but rather the point of force moves to the inside of the pad, where the solder material is the first to be subjected to force and tear, thus improving the defect of the pad being torn from the edge of the pad when the LED is hit. This reduces the risk of the pad falling off when the LED is hit, improving reliability. In addition, even after a severe impact, only the solder material of the LED bead pin breaks while the pad remains intact. In this case, only the LED bead needs to be replaced, which greatly reduces the maintenance difficulty and cost of TOP type LED displays, and is beneficial to industrial production and application.

[0096] This section only introduces the content related to the invention point; the rest can be obtained by referring to relevant technologies, and will not be described in detail here.

[0097] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A TOP-type LED display panel, characterized in that, include: A circuit board, the circuit board including a substrate and at least one pad group, the at least one pad group being disposed on a first surface of the substrate, each pad group including at least two pads; At least one LED bead, each LED bead being connected to one of the pad groups, each LED bead including at least two bead pins, each bead pin being connected to one of the pads; Welding material, wherein the welding material is disposed between the lamp bead pin and the solder pad; Wherein, the orthographic projection of each of the lamp bead pins on each of the substrates is located within the orthographic projection of the pad on the substrate.

2. The TOP-type LED display panel according to claim 1, characterized in that, The orthographic projection of the perimeter of each LED pin on the substrate lies within the orthographic projection of the boundary of the pad on the substrate. Each LED chip includes four chip pins, each pad group includes four pads, and the perimeter of each chip pin is set within the perimeter of its corresponding pad.

3. The TOP-type LED display panel according to claim 2, characterized in that, The length of each LED pin in each LED chip along the first direction is A, the width of each LED pin along the second direction is B, the distance between any two adjacent LED pins along the first direction is D, and the distance between any two adjacent LED pins along the second direction is C. The length of each pad in each pad group along the first direction is A1, the width of each pad in each pad group along the second direction is B1, the distance between any two adjacent pads in each pad group along the first direction is D1, and the distance between any two adjacent pads in each pad group along the second direction is C1. Where, A1=A+(0.12~0.18)mm, B1=B+(0.08~0.12)mm, C1=C-(0.05~0.10)mm, D1=D-(0.08~0.15)mm.

4. The TOP-type LED display panel according to claim 3, characterized in that, The orthographic projection of the welding material on the substrate is partially offset from the orthographic projection of each lamp bead pin on the substrate, and the orthographic projection of the welding material on the substrate is offset to the right relative to the orthographic projection of each lamp bead pin on the substrate.

5. The TOP-type LED display panel according to claim 3, characterized in that, The orthographic projection of the welding material on the substrate is partially offset from the orthographic projection of each of the lamp bead pins on the substrate, and the orthographic projection of the welding material on the substrate is offset to the left relative to the orthographic projection of each of the lamp bead pins on the substrate.

6. The TOP-type LED display panel according to claim 4 or 5, characterized in that, A1=A+(0.15~0.18)mm, B1=B+(0.1~0.12)mm, C1=C-(0.08~0.10)mm, D1=D-(0.12~0.15)mm.

7. The TOP-type LED display panel according to claim 1 or 2, characterized in that, The circuit board further includes a surface solder mask layer that covers the substrate, and the surface solder mask layer has a plurality of discrete and spaced grooves, with each solder pad disposed in one of the grooves; Along the second direction, the height of the pad is less than the height of the surface solder mask around the groove; And / or, the surface solder resist layer is achieved by surface treatment methods such as nickel-gold plating, tin plating, or forming an organic solder resist film on the surface of the solder pad.

8. The TOP-type LED display panel according to claim 1 or 2, characterized in that, The substrate includes a glass fiber layer, and the pads are pressed onto the surface of the glass fiber layer and are tightly bonded to the glass fiber layer; And / or, The pad material includes any one of pure copper, pure copper plated with nickel gold, or pure copper plated with tin.

9. The TOP-type LED display panel according to claim 1 or 2, characterized in that, Each LED chip further includes an LED chip, bonding wires, a packaging layer, and a chip package. The LED chip is disposed on the side of the chip pin facing away from the pad, and the LED chip is connected to the chip pin via the bonding wires. The packaging layer is used to encapsulate the LED chip, the bonding wires, and a portion of the chip pins. The LED chip, the bonding wires, a portion of the chip pins, and the packaging layer are all integrated into the surface-mount chip package. The remaining portion of the chip pins protrudes from the chip package and is soldered to the pad via the soldering material.

10. A TOP-type LED display screen, characterized in that, Includes the TOP type LED display panel as described in any one of claims 1 to 9.

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