Display module and PCB thereof

Abstract

The invention provides a display module and a PCB (Printed Circuit Board) thereof. The PCB comprises a substrate, a plurality of bonding pads and a plurality of solder mask parts. A plurality of bonding pad areas are arranged on the surface of the substrate at intervals. And each bonding pad area is provided with a bonding pad or at least two bonding pads which are distributed at intervals. The plurality of solder mask parts are convexly arranged on the surface of the substrate at intervals, and each solder mask part is correspondingly and annularly arranged on the periphery of one bonding pad area, so that molten solder can be prevented from deviating or flowing to the substrate in the subsequent welding process. Moreover, when the light-absorbing ink layer is subsequently arranged to cover the surface of the PCB, the light-absorbing ink layer part with a certain thickness can be accommodated at the interval between the adjacent solder mask parts, so that the linear distance between the surface, deviating from the substrate, of the light-absorbing ink layer and the surface of the substrate is reduced under the condition of ensuring that the total thickness of the light-absorbing ink layer meets the requirement, and the yield of the PCB is improved. The light-emitting surface shielding caused by the light-absorbing ink layer covering the outer side of the light-emitting main body of the light-emitting unit can be avoided, so that the display effect of the product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of display screens, and particularly to a display module and its PCB board. Background Art

[0002] Light-emitting diodes (LEDs) have been widely used in the fields of lighting and display due to their advantages such as high brightness, long lifespan, low energy consumption, fast response speed, and environmental friendliness.

[0003] Currently, an LED packaging module is formed by placing LED light-emitting units sized 100 - 300 microns on the pads of a PCB board printed with solder paste through equipment, and then through reflow soldering and encapsulating with encapsulation glue by die pressing. In order to prevent the solder paste set on the pads from shifting or flowing during reflow soldering, a solder mask ink layer is often covered on the surface of the substrate of the PCB board located on the outer periphery of the pads to block the solder paste melted at high temperature. And, in order to improve the ink color consistency of the LED display module and increase the contrast, a light-absorbing ink layer with a thickness of 40 - 60 um is covered by bottom inkjet on the surface of the PCB board after the light-emitting units are soldered to cover the background color of the PCB board.

[0004] However, the setting of the solder mask ink layer fills the interval between adjacent pads, making the overall structure composed of the solder mask ink layer and the substrate have a relatively large thickness, and making the interval between the surface of the solder mask ink layer facing away from the substrate and the light-emitting body of the light-emitting unit relatively small, and this interval distance is less than the thickness requirement of the subsequent light-absorbing ink layer for covering the background color of the PCB board. Therefore, under the condition that the thickness of the light-absorbing ink layer can completely cover the background color of the PCB board, while filling the interval between the solder mask ink layer and the light-emitting body of the light-emitting unit, the light-absorbing ink layer will also cover the side surface of the light-emitting body of the light-emitting unit, which will affect the side light emission of the light-emitting unit, resulting in phenomena such as dark and bright, and mosaic on the LED packaging module, thus affecting the display effect of the LED display screen. Summary of the Invention

[0005] The purpose of the present invention is to provide a display module and its PCB board, by improving the PCB board, to solve the problems of dark and bright, and mosaic on the display module caused by the covering of the side surface of the light-emitting body of the light-emitting unit, thereby improving the display effect of the display module.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] According to one aspect of the present application, the present application provides a PCB board, including:

[0008] A substrate, on whose surface there are multiple pad areas arranged at intervals;

[0009] Multiple pads, each pad area is provided with one of the pads or at least two of the pads distributed at intervals;

[0010] Multiple solder mask parts, protruding from the surface of the substrate at intervals, and each solder mask part is correspondingly disposed around the outer periphery of one pad area.

[0011] In some embodiments, the surface of the solder mask part facing away from the substrate is not lower than the surface of the pad facing away from the substrate.

[0012] In some embodiments, the thickness of the solder mask part is H, and the thickness of the pad is h, where H - h ≤ 30um.

[0013] In some embodiments, each pad area is provided with one pad, and the inner periphery of the solder mask part is in contact with the outer periphery of the pad; or,

[0014] Each pad area is provided with at least two pads arranged at intervals, and the outer periphery of the whole formed by all the pads in the pad area is in contact with the inner periphery of the solder mask part.

[0015] In some embodiments, the outer contour of the solder mask part is rectangular, and the solder mask part includes four solder mask edges connected end to end in sequence, and each solder mask edge protrudes from the surface of the substrate.

[0016] In some embodiments, the width of each solder mask edge is 20μm - 40μm.

[0017] In some embodiments, the thickness of each solder mask edge is 15μm - 50μm.

[0018] In some embodiments, the solder mask part is formed by screen printing, exposure, development and curing of solder resist ink in sequence.

[0019] According to another aspect of the present application, the present application further provides a display module, including a plurality of light-emitting units, an absorbing ink layer and a PCB board as described in any one of the above; all the pads in each pad area of the PCB board are used for connecting and fixing with one of the light-emitting units; the absorbing ink layer covers the surface of the PCB board.

[0020] In some embodiments, the light-emitting unit includes a light-emitting body and pins connected to the light-emitting body, and the pins protrude from the surface of the light-emitting body, and the pins are used for connecting and fixing with the pads;

[0021] The surface of the absorbing ink layer facing away from the PCB board is in contact with the surface of the light-emitting body close to the PCB board;

[0022] The thickness of the absorbing ink layer is 40μm - 60μm.

[0023] As can be seen from the above technical solutions, the present invention has at least the following advantages and positive effects:

[0024] In the present application, since a solder mask portion is provided on the outer periphery of each pad region, during the subsequent soldering process, the molten solder can be blocked from shifting or flowing onto the substrate, thereby preventing the problem of short circuit of the circuit on the substrate caused by solder bridging, and thus achieving the purpose of protecting the circuit on the substrate.

[0025] Moreover, since multiple solder mask portions are spaced apart on the surface of the substrate, a part of the surface of the substrate can be exposed. During the subsequent process of setting the light-absorbing ink layer to cover the surface of the PCB board, the above design enables the light-absorbing ink layer to first fill the intervals between adjacent solder mask portions and then spread to cover the surfaces of the solder mask portions and the pads. That is, in the present application, the solder mask layer in the prior art is divided into multiple solder mask portions that are independently and spaced apart. This enables a certain thickness of the light-absorbing ink layer portion to be first accommodated in the intervals between adjacent solder mask portions. Under the condition that the total thickness of the light-absorbing ink layer meets the requirements, the linear distance between the surface of the light-absorbing ink layer facing away from the substrate and the surface of the substrate is reduced, and it can be avoided that the light-absorbing ink layer covers the outside of the light-emitting body of the light-emitting unit due to too large a linear distance, thereby solving the problem that the light-absorbing ink layer covers the side surface of the light-emitting unit and affects its side surface light emission, resulting in problems such as uneven brightness and color distortion of the product, improving the light-emitting effect of the light-emitting unit, and thus enabling the product produced using the PCB board provided in the present application to have a better display effect and enhancing the user experience. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of the PCB board in this embodiment.

[0027] Figure 2 is Figure 1 a schematic structural diagram of the PCB board in [reference] along the A-A direction.

[0028] Figure 3 is a schematic structural diagram of the display module in this embodiment.

[0029] Figure 4 is Figure 3 an enlarged structural diagram at B in [reference].

[0030] The description of the reference numerals is as follows:

[0031] 100, display module; 1, light-emitting unit; 11, light-emitting body; 12, pin; 2, light-absorbing ink layer; 3, PCB board; 31, substrate; 311, pad region; 32, pad; 33, solder mask portion; 331, solder mask edge; 4, solder paste layer; 5, encapsulation layer. Detailed Embodiments

[0032] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments, all of which do not depart from the scope of the present invention, and the descriptions and illustrations therein are for illustrative purposes in nature and not intended to limit the present invention.

[0033] In the description of the present application, it should be understood that in the embodiments shown in the drawings, the indication of the direction or positional relationship (such as up, down, left, right, front, and back, etc.) is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. When these elements are in the positions shown in the drawings, these descriptions are appropriate. If the description of the positions of these elements changes, then the indication of these directions also changes accordingly.

[0034] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality of" means two or more, unless otherwise specifically defined.

[0035] The present application provides a PCB board for use in the field of display screens.

[0036] The following, in conjunction with the drawings, details the specific embodiments of the PCB board of the present application.

[0037] Figure 1 is a schematic structural diagram of the PCB board 3 in this embodiment, Figure 2 is Figure 1 a schematic structural diagram of the PCB board 3 along the A-A direction.

[0038] Referring to Figure 1 and Figure 2 , the PCB board 3 includes a substrate 31, a plurality of pads 32, and a plurality of solder mask parts 33.

[0039] A plurality of pad areas 311 are provided at intervals on the surface of the substrate 31. Specifically, the plurality of pad areas 311 are arranged in an array.

[0040] Among them, each pad area 311 is provided with one pad 32 or at least two pads 32 distributed at intervals. Specifically, when each pad area 311 is provided with one pad 32, the pad area 311 is the contact surface of the pad 32 and the substrate 31. When at least two pads 32 are provided at intervals within each pad area 311, the pad area 311 is: the area on the surface of the substrate 31 occupied by the whole formed by all the pads 32 located within the pad area 311.

[0041] In this embodiment, it is described by taking an example that each pad area 311 is provided with four pads 32, and among them, the four pads 32 are arranged in an array.

[0042] The pad 32 is made of copper material, which enables the pad 32 to have good electrical conductivity and so on.

[0043] A plurality of solder mask portions 33 protrude from the surface of the substrate 31 at intervals, and each solder mask portion 33 is correspondingly disposed around the outer periphery of a pad area 311.

[0044] In this application, since a solder mask portion 33 is provided on the outer periphery of each pad area 311, during the subsequent soldering process, it can block the molten solder from shifting or flowing onto the substrate 31, so as to prevent the problem of short - circuit of the circuit on the substrate 31 caused by solder bridging, thereby achieving the purpose of protecting the circuit on the substrate 31.

[0045] Moreover, since the plurality of solder mask portions 33 are arranged at intervals on the surface of the substrate 31, a part of the surface of the substrate 31 can be exposed. During the subsequent process of setting the light - absorbing ink layer 2 to cover the surface of the PCB board 3, the above design enables the light - absorbing ink layer 2 to first fill the intervals between adjacent solder mask portions 33, and then spread to cover the surfaces of the solder mask portions 33 and the pads 32. That is to say, in this application, the existing solder mask layer is divided into a plurality of solder mask portions 33 that are independently and spaced apart. This enables a certain thickness of the light - absorbing ink layer 2 to be first accommodated in the intervals between adjacent solder mask portions 33. Under the condition that the total thickness of the light - absorbing ink layer 2 meets the requirements, the linear distance between the surface of the light - absorbing ink layer 2 facing away from the substrate 31 and the surface of the substrate 31 is reduced, and it can be avoided that due to the too large linear distance, the light - absorbing ink layer 2 covers the outside of the light - emitting body 11 of the light - emitting unit 1, thereby solving the problem that the light - absorbing ink layer 2 covers the side of the light - emitting unit 1 and affects its side - emitting, resulting in problems such as dark - bright and mosaic on the product, so as to improve the light - emitting effect of the light - emitting unit 1, and thus enabling the product produced by using the PCB board 3 provided in this application to have a good display effect and enhancing the user experience.

[0046] It should be noted that the thickness in this application refers to the dimension in the direction perpendicular to the surface of the substrate 31.

[0047] Continue to refer to Figure 1 and Figure 2, when at least two pads 32 are arranged at intervals within each pad area 311, the outer periphery of the whole formed by all the pads 32 within the pad area 311 fits with the inner periphery of the solder mask portion 33. In this way, during the subsequent soldering process, the flow range of the melted solder can be precisely restricted to prevent the melted solder from shifting or flowing onto the substrate 31, effectively preventing the problem of short - circuit of the circuit on the substrate 31 caused by solder bridging. And, through the solder mask portion 33, the boundary of the whole formed by all the pads 32 within the pad area 311 can also be defined, ensuring that the solder only adheres to the exposed pad area 311, avoiding soldering defects or insufficient solder joint strength caused by solder diffusion. In addition, the above design enables the solder mask portion 33 to cover the outer peripheral surface of the pad 32 to form a physical barrier to block pollutants such as moisture, dust, and acidic gases from directly contacting the copper - based pad 32, significantly reducing the oxidation risk of the pad 32.

[0048] Alternatively, when only one pad 32 is provided in each pad area 311, the inner periphery of the solder mask portion 33 fits with the outer periphery of the pad 32.

[0049] In this embodiment, the surface of the solder mask portion 33 facing away from the substrate 31 is not lower than the surface of the pad 32 facing away from the substrate 31. This enables the solder mask portion 33 to form an effective physical barrier. During the subsequent soldering process, the melted solder can be strictly restricted within the pad area 311, significantly reducing the risk of the melted solder shifting or flowing onto the substrate 31, thereby achieving the purpose of protecting the circuit on the substrate 31.

[0050] Specifically, the thickness of the solder mask portion 33 is H, and the thickness of the pad 32 is h, where H - h ≤ 30um. The thickness direction in this article refers to the direction perpendicular to the surface of the substrate 31, and the same applies hereinafter.

[0051] The outer contour of the solder mask portion 33 is rectangular. The solder mask portion 33 includes four solder mask edges 331 connected end - to - end in sequence, and each solder mask edge 331 protrudes from the surface of the substrate 31.

[0052] In this embodiment, the cross - section of each solder mask edge 331 is rectangular, which is convenient for the inner side surface of each solder mask edge 331 to fit with the outer side of the pad 32. In other embodiments, the cross - section of the solder mask edge 331 can also be trapezoidal or other shapes.

[0053] The width of each solder mask edge 331 is 20 μm to 40 μm. The thickness of each solder mask edge 331 is 15 μm to 50 μm. The above settings enable the solder mask edge 331 to effectively stop the melted solder while having a smaller width, thereby expanding the interval between adjacent solder mask parts 33 to expose more of the surface of the substrate 31, avoiding excessive occupation of the surface of the substrate 31 by the solder mask parts 33, increasing the contact area between the surface of the substrate 31 and the light-absorbing ink layer 2, enabling most of the light-absorbing ink layer 2 to directly cover the surface of the substrate 31, ensuring that under the condition of meeting the requirements for the thickness of the light-absorbing ink layer 2, there is a smaller linear distance between the surface of the light-absorbing ink layer 2 facing away from the substrate 31 and the surface of the substrate 31, and avoiding the light-absorbing ink layer 2 covering the outside of the light-emitting body 11 of the light-emitting unit 1 due to an excessive linear distance, thereby solving the problem that the light-absorbing ink layer 2 covers the side of the light-emitting unit 1, ensuring the light-emitting effect of the light-emitting unit 1, and achieving an improvement in the display effect of the product produced using the PCB board 3 provided by the present application. In addition, the above design can also reduce the materials required to form the solder mask edge 331 and lower the production cost.

[0054] In this embodiment, the solder mask part 33 is formed by using solder resist ink. Specifically, the solder mask part 33 is formed by successively performing screen printing, exposure, development, and curing on the solder resist ink. Among them, screen printing: The liquid solder resist ink is coated on the outer periphery of the pad area 311 by screen printing. Exposure: The solder resist ink is exposed using ultraviolet light through a negative film, and the solder resist ink is selectively cured. At this time, the unexposed area remains soluble. Development: The solder resist ink in the unexposed area is dissolved by an alkaline solution to remove the excess solder resist ink, exposing the pad 32, and initially forming a rectangular shape. Curing: The solder resist ink is completely cured by high-temperature baking to form the solder mask part 33 described above.

[0055] Among them, between screen printing and exposure, there is also a pre-baking treatment, that is: the liquid solder resist ink is pre-baked to transform it from a liquid state to a semi-cured state to avoid adhesion to the negative film during subsequent exposure.

[0056] In this embodiment, the solder resist ink for forming the solder mask part 33 can be colors such as black, white, and green.

[0057] The present application also provides a display module 100. The following will describe in detail the embodiments of the display module 100 in the present application with reference to the accompanying drawings.

[0058] Figure 3 is a schematic structural diagram of the display module 100 in this embodiment, Figure 4 is Figure 3 the enlarged structural diagram at position B in

[0059] Refer to Figure 3 andFigure 4 , the display module 100 includes a plurality of light-emitting units 1, an absorbent ink layer 2, and a PCB board 3 as described above.

[0060] Among them, each light-emitting unit 1 is correspondingly fixedly connected to all pads 32 within a pad area 311.

[0061] The light-emitting unit 1 includes a light-emitting body 11 and pins 12. The pins 12 are connected to the light-emitting body 11, and the pins 12 protrude from the surface of the light-emitting body 11. The pins 12 are used for fixedly connecting to the pads 32. Among them, the surface of the light-emitting unit 1 facing away from the substrate 31 and its peripheral side surfaces are all light-emitting surfaces.

[0062] In this embodiment, each light-emitting unit 1 includes four pins 12. The four pins 12 are arranged in an array, and the four pins 12 are fixedly connected to four pads 32 in the pad area 311 in a one-to-one correspondence. Among them, the surface area of the pad 32 facing away from the substrate 31 is larger than the surface area of the pin 12 facing away from the light-emitting body 11, which can ensure sufficient contact between the pin 12 and the pad 32.

[0063] Specifically, the pin 12 and the pad 32 are fixed by solder. Among them, the solder is solder paste. The solder paste is first melted by high temperature to form liquid tin. During the continuous heating process, the liquid tin solidifies between the pin 12 of the light-emitting unit 1 and the pad 32 to form a solder paste layer 4, so as to fix the pin 12 and the pad 32. At this time, the design that the surface area of the pad 32 facing away from the substrate 31 is larger than the surface area of the pin 12 facing away from the light-emitting body 11 can also enable more solder paste to adhere to the surface of the pad 32, so as to ensure that the solder paste layer 4 after melting and solidifying can at least completely cover the surface of the pin 12 close to the pad 32, so as to increase the welding reliability and improve the connection strength between the light-emitting unit 1 and the pad 32.

[0064] The absorbent ink layer 2 covers the surface of the PCB board 3. And, the absorbent ink layer 2 is located outside the pins 12 of the light-emitting unit 1. Specifically, in the direction parallel to the PCB board 3, the absorbent ink layer 2 covers the surface of the substrate 31 at the interval between adjacent solder mask parts 33, the surface of the solder mask parts 33, and the surface of one end of the pad 32 close to the solder mask part 33.

[0065] In this embodiment, the surface of the light-absorbing ink layer 2 facing away from the PCB board 3 is in contact with the surface of the light-emitting body 11 close to the PCB board 3. In this way, while ensuring that the thickness of the light-absorbing ink layer 2 meets the requirements, it is possible to avoid blocking the light-emitting surface on the periphery of the light-emitting body 11, thereby improving the light-emitting effect of the light-emitting body 11. Specifically, in the direction perpendicular to the surface of the substrate 31, the light-absorbing ink layer 2 completely covers the side surface of the solder mask portion 33, the side surface of the solder paste layer 4 close to the solder mask portion 33, and the side surface of the portion of the lead 12 of the light-emitting unit 1 protruding from the light-emitting body 11 close to the solder mask portion 33. This design enables the light-absorbing ink to absorb the stray light leaking from the lead 12 area of the light-emitting unit 1, avoiding interference with the main optical path or causing light pollution, thereby improving the display effect of the display module 100.

[0066] Among them, the light-absorbing ink layer 2 is made of a black light-absorbing ink material. Specifically, a black light-absorbing ink material can be set in the intervals between multiple solder mask portions 33 through a printing device, and the black light-absorbing ink material is allowed to flow to the side surface of the lead 12 of the light-emitting unit 1 close to the solder mask portion 33, so that in the direction parallel to the substrate 31, the black light-absorbing ink material can cover the surface of the substrate 31 at the intervals between adjacent solder mask portions 33, the surface of the solder mask portion 33, and the surface of the pad 32 close to the solder mask portion 33, and, in the direction perpendicular to the surface of the substrate 31, can completely cover the side surface of the solder mask portion 33, the side surface of the solder paste layer 4 close to the solder mask portion 33, and the side surface of the portion of the lead 12 of the light-emitting unit 1 protruding from the light-emitting body 11 close to the solder mask portion 33. Then, it is heated and cured to obtain the light-absorbing ink layer 2.

[0067] The thickness of the light-absorbing ink layer 2 is 40μm - 60μm. This design enables the light-absorbing ink layer 2 to effectively absorb the stray light of the light-emitting unit 1, while not blocking the main optical path, achieving a balance between absorbing stray light and maintaining the light effect, improving the light-emitting uniformity and contrast, and at the same time being able to improve the ink color consistency of the display module 100, thereby improving the display effect of the display module 100.

[0068] Reference Figure 3 , the display module 100 further includes a packaging layer 5. The packaging layer 5 covers the light-emitting unit 1 and the light-absorbing ink layer 2. The packaging layer 5 can provide physical protection for the light-emitting unit 1 and the circuits on the substrate 31 to prevent external pollutants such as dust and moisture from entering the interior of the display module 100, protecting the light-emitting unit 1, the circuits, etc. from being damaged, and being able to prevent damage caused by external forces such as collision and vibration. Moreover, the packaging layer 5 can also improve the refraction and reflection of the light emitted by the light-emitting unit 1, and can evenly disperse the light, reducing color difference, ensuring the color consistency of the display module 100, and improving the display effect of the display module 100.

[0069] Among them, the material of the encapsulation layer 5 can be one or several of epoxy resin, silicone resin, silicone-modified epoxy resin, etc.

[0070] As can be seen from the above technical solutions, the present invention has at least the following advantages and positive effects:

[0071] In this application, since a solder mask portion is provided on the outer periphery of each pad area, it can prevent the molten solder from shifting or flowing onto the substrate during the subsequent soldering process, so as to prevent the problem of short circuit of the circuit on the substrate caused by solder bridging, thereby achieving the purpose of protecting the circuit on the substrate.

[0072] Moreover, since multiple solder mask portions are arranged at intervals on the surface of the substrate, a part of the surface of the substrate can be exposed. During the subsequent process of setting the light-absorbing ink layer to cover the surface of the PCB board, the above design enables the light-absorbing ink layer to first fill the intervals between adjacent solder mask portions, and then spread to cover the surfaces of the solder mask portions and the pads. That is to say, in this application, the solder mask layer in the prior art is divided into multiple solder mask portions arranged independently at intervals, which enables a certain thickness of the light-absorbing ink layer portion to be accommodated in the intervals between adjacent solder mask portions first. Under the condition that the total thickness of the light-absorbing ink layer meets the requirements, the linear distance between the surface of the light-absorbing ink layer away from the substrate and the surface of the substrate is reduced, and it can be avoided that the light-absorbing ink layer covers the outside of the light-emitting body of the light-emitting unit due to too large a linear distance, thereby solving the problem that the light-absorbing ink layer will cover the side surface of the light-emitting unit and affect its side light emission, resulting in problems such as dark and bright or mosaic on the product, so as to improve the light-emitting effect of the light-emitting unit, and thus enable the display module produced by the PCB board provided by this application to have a good display effect and improve the user experience.

[0073] Although the present invention has been described with reference to several exemplary embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be broadly construed within the spirit and scope defined by the appended claims. Therefore, all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A PCB board, characterized in that: include: A substrate, a surface of which is provided with a plurality of pad areas at intervals; A plurality of pads, each pad area being provided with one pad or at least two pads spaced apart from each other; A plurality of soldering protection parts are protruded and arranged on the surface of the substrate at intervals, and each of the soldering protection parts is correspondingly arranged around the periphery of one of the pad areas.

2. The PCB board according to claim 1, characterized in that: The surface of the solder resist facing away from the substrate is not lower than the surface of the pad facing away from the substrate.

3. The PCB board according to claim 2, characterized in that: The thickness of the solder mask is H, and the thickness of the pad is h, wherein Hh≤30 um.

4. The PCB board according to claim 1, characterized in that: Each pad area is provided with a pad, and the inner periphery of the solder mask is in contact with the outer periphery of the pad; or, At least two pads are arranged at intervals in each pad area, and the outer periphery of the whole formed by all the pads in the pad area is in contact with the inner periphery of the solder resist.

5. The PCB board according to claim 1, characterized in that: The outer contour of the soldering-proof part is rectangular, and the soldering-proof part comprises four soldering-proof ribs which are connected end to end in sequence, and each of the soldering-proof ribs is arranged to protrude from the surface of the substrate.

6. The PCB board according to claim 5, characterized in that: The width of each solder resist rib is 20 μm to 40 μm.

7. The PCB board according to claim 5, characterized in that: The thickness of each solder resist rib is 15 μm to 50 μm.

8. The PCB board according to claim 1, characterized in that: The solder resist is formed by sequentially screen printing, exposure, development and curing of solder resist ink.

9. A display module, characterized in that: It comprises a plurality of light-emitting units, a light-absorbing ink layer and a PCB board as claimed in any one of claims 1 to 8; all pads in each pad area of ​​the PCB board are used to be connected and fixed with one of the light-emitting units; the light-absorbing ink layer covers the surface of the PCB board.

10. The display module according to claim 9, characterized in that: The light-emitting unit comprises a light-emitting body and pins connected to the light-emitting body, and the pins protrude from the surface of the light-emitting body, and the pins are used to be connected and fixed to the pads; The surface of the light-absorbing ink layer facing away from the PCB board is in contact with the surface of the light-emitting body close to the PCB board; The thickness of the light-absorbing ink layer is 40 μm to 60 μm.

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