CN117059710A - LED display module, manufacturing method thereof and LED display screen - Google Patents

Abstract

The application provides a manufacturing method of an LED display module, which comprises the following steps: providing a PCB, wherein a layer of solder resist ink is formed on the front surface of the PCB, and a window is formed in the solder resist ink to expose a bonding pad on the PCB; the method comprises the steps of fixing a crystal, providing a pixel unit, wherein the pixel unit comprises a black substrate, a plurality of light emitting chips packaged on the front surface of the black substrate and welding pins formed on the back surface of the black substrate; correspondingly welding the welding feet on the welding pads; the projection outline of the black substrate on the PCB is positioned in the window, and gaps are formed among the black substrate, the solder resist ink and the bonding pads; and (3) ink-jetting, namely, spraying black ink in the solder resist ink and the gaps. The application also provides the LED display module and the LED display screen manufactured by the method. The application not only improves the consistency and contrast of the black screen of the LED display module, but also reduces the requirements on die bonding precision, windowing precision and solder resist ink precision so as to reduce the manufacturing cost.

Description

LED display module, manufacturing method thereof and LED display screen

Technical Field

The application belongs to the technical field of LED display, and particularly relates to an LED display module, a manufacturing method thereof and an LED display screen.

Background

Not only the performance of the LED display panel at the time of lighting display affects the image quality, but also the glossiness, chromaticity, black uniformity, and the like at the time of black display are important to the image quality. When the glossiness of the black screen is too high, the glare is serious, and the watching experience is influenced; when the chromaticity of the black screen is not black enough, the black screen is greatly influenced by ambient light, the low-gray display is easy to turn white, and the contrast of the display picture is low; when the consistency of black is poor, black is not uniform, and pits are serious. The viewing distance of the LED display screen is reduced along with the size of the LED display screen, and the problems of insufficient blackness, poor consistency and the like in the process of screen blacking are more and more obvious.

The film spraying technology is widely used by the LED display screen industry for improving the blackness of a black screen and improving the consistency of black. For COB (chip on Board) technology, black ink is sprayed between pixels to remarkably improve blackness of an LED display screen and cover chromatic aberration caused by a PCB. However, the pixel gap is very small, the precision of the ink-jet process is insufficient to realize ink-jet among pixels, and the difficulty of the film-jet process among pixels is higher and higher along with the reduction of the dot spacing.

In this regard, industry personnel developed a novel package architecture, MIP (Micro LED in package) structure, for Micro LEDs, which implements the organic combination of Micro LEDs and discrete devices by separately packaging a large-area monolithic display panel. Specifically, the MIP structure includes a black substrate, a plurality of light emitting chips encapsulated on the front surface of the black substrate, and solder fillets formed on the back surface of the black substrate. When the LED display module is manufactured, a PCB is manufactured firstly, a layer of solder resist ink is formed on the front surface of the PCB, and a window is formed in the solder resist ink to expose a bonding pad on the PCB; and then welding the welding feet of the black substrate on the welding pads of the PCB. However, the MIP structure has small size and high requirement on the precision of die bonding. If the die bonding precision does not meet the requirement, the situation of distortion and deviation of the MIP structure may occur, the area without solder resist ink may leak out, the problems of reflection, white exposure and the like may be caused, and the consistency and contrast of the black screen may be reduced. At present, the die bonding equipment of display screen manufacturers is difficult to achieve the precision required by the MIP structure, the cost for replacing the die bonding equipment with high precision is high, and the product competitiveness can be greatly reduced. In addition, the requirements on the windowing precision and thickness precision of the solder resist ink on the PCB are also very high. The height of the solder fillets of the MIP structure is only about 20um, and when the thickness of the solder resist ink is too high or the window is too small, the solder fillets can cause the problems of cold joint and the like. If the PCB factory is required to improve the ink-jet precision, the material management and control difficulty is increased, and the material cost of the PCB is also greatly improved, so that the technology is difficult to realize large-scale popularization at the present stage.

Disclosure of Invention

The embodiment of the application aims to provide an LED display module, a manufacturing method thereof and an LED display screen, which are used for solving the technical problems of poor consistency and low contrast of a black screen caused by low die bonding precision, low solder mask ink windowing precision and low thickness precision of an MIP structure in the prior art.

In order to achieve the above purpose, the application adopts the following technical scheme: in a first aspect, a method for manufacturing an LED display module is provided, including the following steps:

providing a PCB, wherein a layer of solder resist ink is formed on the front surface of the PCB, and a window is formed in the solder resist ink to expose a bonding pad on the PCB;

the method comprises the steps of fixing a crystal, and providing a pixel unit, wherein the pixel unit comprises a black substrate, a plurality of light emitting chips packaged on the front surface of the black substrate and welding pins formed on the back surface of the black substrate; correspondingly welding the welding pins on the welding pads; the projection outline of the black substrate on the PCB is positioned in the window, and gaps are formed among the black substrate, the solder resist ink and the bonding pads;

and (3) ink-jetting, namely spraying black ink in the solder resist ink and the gaps.

In one possible design, the blackness of the black ink is greater than the blackness of the solder mask ink.

In one possible design, a shutter is provided above the black substrate to block the black substrate when ink is ejected.

In one possible design, the projection contour of the shielding element on the black substrate is located within a peripheral edge of the black substrate and surrounds the light-emitting chips.

In one possible design, the black ink has a thickness on the solder resist ink after ink jetting that is greater than the height of the black substrate above the solder resist ink; the black ink covers a peripheral edge of the black substrate.

In one possible design, the black ink has a thickness on the solder resist ink after ink jetting that is less than the height of the black substrate above the solder resist ink; the black ink covers a peripheral edge of the black substrate.

In one possible design, the black ink covers less than 10um in width at a peripheral edge of the black substrate;

and/or, the thickness of the black ink covering a peripheral edge of the black substrate is less than 10um.

In one possible design, a transparent oleophobic layer is formed on the front side of the black substrate prior to the ink ejection, the oleophobic layer covering at least each of the light emitting chips.

The manufacturing method of the LED display module provided by the application has the beneficial effects that: according to the manufacturing method of the LED display module, the projection outline of the black substrate on the PCB is positioned in the window, so that a space is reserved between the peripheral outer edge of the black substrate and the peripheral inner edge of the window, even if the black substrate is still positioned in the window due to low die bonding precision and is inclined or deviated, gaps between the solder resist ink and the black substrate can be filled by black ink, the problems of reflection, white exposure and the like are avoided, the consistency and the contrast of the black screen are improved, and meanwhile, the die bonding precision requirement is reduced, so that the die bonding difficulty is reduced. In addition, due to the large window size, the window opening precision is not high or the thickness precision of the solder resist ink is not high, the phenomenon of cold joint cannot occur, and meanwhile, the window opening precision requirement and the thickness precision requirement of the solder resist ink can be reduced, so that the manufacturing difficulty and the manufacturing cost are greatly reduced. In addition, the black ink is sprayed in the solder resist ink and the gaps, so that the gaps can be filled, the phenomena of reflection and white exposure are avoided, and meanwhile, the black consistency and contrast of the LED display module can be improved.

In a second aspect, the application also provides an LED display module, which is manufactured by the manufacturing method of the LED display module;

the LED display module includes:

the PCB is provided with a layer of solder resist ink on the front surface, and the solder resist ink is provided with a window to expose a bonding pad on the PCB;

the pixel unit comprises a black substrate, a plurality of light emitting chips packaged on the front surface of the black substrate and welding pins formed on the back surface of the black substrate; the welding leg is welded on the welding pad; the projection outline of the black substrate on the PCB is positioned in the window, and gaps are formed among the black substrate, the solder resist ink and the bonding pads;

and black ink formed on the solder resist ink and filled in the gaps.

The LED display module provided by the application has the beneficial effects that: the LED display module provided by the embodiment of the application is manufactured by the manufacturing method of the LED display module, so that the black screen of the LED display module is high in blackness and good in black consistency.

In a third aspect, the application further provides an LED display screen, which comprises the LED display module.

The LED display screen provided by the application has the beneficial effects that: according to the LED display screen provided by the embodiment of the application, through the design of the LED display module, the blackness of the LED display screen is high, and the blackness consistency is good.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flow chart of a method for manufacturing an LED display module according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a PCB board of an LED display module according to an embodiment of the present application;

fig. 3 is a schematic side view of a pixel unit of an LED display module according to an embodiment of the present application;

fig. 4 is a schematic top view of a pixel unit of an LED display module according to an embodiment of the present application;

fig. 5 is a schematic bottom view of a pixel unit of an LED display module according to an embodiment of the present application;

fig. 6 is a schematic structural diagram of a bare die of an LED display module according to an embodiment of the present application;

FIG. 7 is a schematic side view of a bare die of the LED display module of FIG. 6;

fig. 8 is a schematic structural diagram of an inkjet board of an LED display module according to an embodiment of the present application;

FIG. 9 is a schematic side view of an ink jet plate of the LED display module of FIG. 8;

fig. 10 is a schematic diagram of a shielding member disposed above an LED display module according to an embodiment of the present application;

FIG. 11 is a schematic diagram of an ink-jet board structure of an LED display module according to an embodiment of the present application;

FIG. 12 is a schematic package diagram of the LED display module of FIG. 11;

fig. 13 is another schematic package diagram of an LED display module according to an embodiment of the present application;

FIG. 14 is an enlarged schematic view of the LED display module of FIG. 13;

fig. 15 is a schematic diagram of another package of an LED display module according to an embodiment of the present application.

Wherein, each reference sign in the figure:

100. a PCB board; 110. a bonding pad; 200. solder resist ink; 210. a window; 300. a pixel unit; 310. a black substrate; 320. welding feet; 330. a light emitting chip; 400. black ink; 500. a slit; 600. an encapsulation layer; 700. an oleophobic layer; 800. a shield.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.

It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

The MIP structure comprises a black substrate, a plurality of light emitting chips encapsulated on the front surface of the black substrate and welding pins formed on the back surface of the black substrate. When the LED display module is manufactured, a PCB is manufactured firstly, a layer of solder resist ink is formed on the front surface of the PCB, and a window is formed in the solder resist ink to expose a bonding pad on the PCB; and then welding the welding feet of the black substrate on the welding pads of the PCB. However, the MIP structure has small size and high requirement on the precision of die bonding. If the die bonding precision does not meet the requirement, the situation of distortion and deviation of the MIP structure may occur, the area without solder resist ink may leak out, the problems of reflection, white exposure and the like may be caused, and the consistency and contrast of the black screen may be reduced. At present, the die bonding equipment of display screen manufacturers is difficult to achieve the precision required by the MIP structure, the cost for replacing the die bonding equipment with high precision is high, and the product competitiveness can be greatly reduced. In addition, the requirements on the windowing precision and thickness precision of the solder resist ink on the PCB are also very high. The height of the solder fillets of the MIP structure is only about 20um, and when the thickness of the solder resist ink is too high or the window is too small, the solder fillets can cause the problems of cold joint and the like. If the PCB factory is required to improve the ink-jet precision, the material management and control difficulty is increased, and the material cost of the PCB is also greatly improved, so that the technology is difficult to realize large-scale popularization at the present stage.

In order to solve the above problems, the embodiment of the application provides a method for manufacturing an LED display module.

Referring to fig. 1, a method for manufacturing an LED display module according to an embodiment of the present application will now be described.

The manufacturing method of the LED display module comprises the following steps:

s10: referring to fig. 2, a PCB board 100 is provided, a layer of solder resist ink 200 is formed on the front surface of the PCB board 100, and a window 210 is formed on the solder resist ink 200 to expose a pad 110 on the PCB board 100;

s20: the die bonding is performed to provide a pixel unit 300, referring to fig. 3 to 5, the pixel unit 300 includes a black substrate 310, a plurality of light emitting chips 330 encapsulated on the front surface of the black substrate 310, and solder fillets 320 formed on the back surface of the black substrate 310; referring to fig. 6 and 7, soldering feet 320 are correspondingly soldered on the bonding pads 110 to obtain a bare chip 1000; the projection contour of the black substrate 310 on the PCB board 100 is located in the window 210, and a gap 500 is formed between the black substrate 310, the solder resist ink 200 and the bonding pad 110;

s30: inkjet, referring to fig. 8 and 9, black ink 400 is sprayed in the solder resist ink 200 and the gap 500 to obtain an inkjet plate 2000.

The solder fillets 320 on the black substrate 310 and the pads 110 on the PCB board 100 are electrically connected and fixed by solder paste, and the solder resist ink 200 is used for preventing the solder paste from flowing randomly to cause short circuit.

In addition, referring to fig. 5, the projection profile of the black substrate 310 on the PCB 100 is located in the window 210, which means that after the black substrate 310 is soldered on the pad 110 of the PCB 100, the projection profile of the black substrate 310 on the PCB 100 is located in the window 210, that is, a space is provided between a peripheral outer edge of the black substrate 310 and a peripheral inner edge of the window 210. For example, when the black substrate 310 and the window 210 are both square, the side length of the black substrate 310 is smaller than the side length of the window 210; when the black substrate 310 and the window 210 are rectangular, the length of the black substrate 310 is smaller than the length of the window 210, and the width of the black substrate 310 is smaller than the width of the window 210; when both the black matrix 310 and the window 210 are circular, the radius of the black matrix 310 is smaller than the radius of the window 210. In summary, the window 210 is enclosed outside the black substrate 310, and a space is provided between the window 210 and the black substrate 310, so that the black substrate 310 is still located inside the window 210 even when the black substrate 310 is skewed or offset due to low die bonding precision, and in addition, the gap 500 between the solder mask ink 200 and the black substrate 310 can be filled by the black ink 400, so that the problems of light reflection, white exposure and the like are not caused, the consistency and contrast of the black screen are improved, and meanwhile, the die bonding precision requirement is reduced, so that the die bonding difficulty is reduced. In addition, due to the large size of the window 210, the window opening precision is not high or the thickness precision of the solder mask ink 200 is not high, the phenomenon of cold joint cannot occur, and meanwhile, the window opening precision requirement and the thickness precision requirement of the solder mask ink 200 can be reduced, so that the manufacturing difficulty and the manufacturing cost are greatly reduced.

In addition, the black ink 400 is sprayed in the solder resist ink 200 and the gap 500, so that the gap 500 can be filled, the phenomena of reflection and white exposure are avoided, and the black consistency and contrast of the LED display module can be improved.

In one embodiment, referring to fig. 2 and fig. 5, a plurality of groups of bonding pads 110 are formed on the PCB board 100, each group of bonding pads 110 is distributed on the PCB board 100 in a matrix, each group of bonding pads 110 includes four bonding pads 110, and the four bonding pads 110 are respectively arranged corresponding to four solder fillets 320 on the black substrate 310. It will be appreciated that in other embodiments of the present application, the distribution of the pads 110 may be set according to actual requirements, and the number of pads 110 in each group may also be set according to the number of fillets 320 on the black matrix 310.

In one embodiment, the black substrate 310 may be a black or dark substrate such as a BT plate, FR-4, silicon plate, BBS, PC, or the like, preferably a black BT plate. The black substrate 310 may have any shape such as a square, a rectangle, or a circle, and is preferably a square. Correspondingly, the shape of the window 210 may be adapted according to the shape of the black matrix 310.

In one embodiment, referring to fig. 2 and 3, assuming that the side length of the window 210 is a and the side length of the black substrate 310 is b, 10% < (a-b)/b <40%, where the value of a-b represents the distance from the outer edge of the black substrate 310 to the inner edge of the window 210. If the distance is too close, when the die bonding precision is insufficient to cause the pixel unit 300 to have a bit of skew, the solder resist ink 200 is easy to block the solder fillets 320 to form a dummy solder, that is, the die bonding precision of the black substrate 310 is increased, and the die bonding difficulty is increased; too far distance results in solder resist ink 200 being too far from bond pad 110, and solder resist ink 200 does not function as a solder resist, and does not function to prevent solder paste from flowing randomly, resulting in a short circuit.

Preferably, 15% < (a-b)/b <25%, by setting the interval between the black matrix 310 and the window 210 within a certain range, it is possible to ensure that enough black ink 400 is sprayed on the solder resist ink 200 to ensure black uniformity of the LED display module, while also avoiding the black ink 400 from being sprayed on the black matrix 310.

Alternatively, the black substrate 310 has a side length of less than 500 μm.

In one embodiment, the light emitting chip 330 is a Micro-LED light emitting chip 330, which may be three primary colors of R/G/B, or may be four primary, five primary or six primary light emitting chips 330. The light emitting chips 330 may be arranged side by side on the black matrix 310, or may be vertically arranged on the black matrix 310 or may be arranged in any form.

In one embodiment, the light emitting chip 330 is encapsulated on the black substrate 310 with a transparent material such as epoxy or sapphire on the surface of the pixel unit 300.

In one embodiment, the black ink 400 has a blackness that is greater than the blackness of the solder mask ink 200. In general, although the solder resist ink 200 is black, the jetness of the solder resist ink 200 is not high, in order to improve the jetness of the whole display module, the application forms a layer of black ink 400 with higher jetness above the solder resist ink 200, and simultaneously fills the gap 500 between the solder resist ink 200 and the black substrate 310 through the black ink 400, thereby improving the black consistency and contrast of the whole LED display module.

Alternatively, the black ink 400 may be selected to have a good wettability of the black ink 400 to ensure that the black ink 400 is able to sufficiently wet the solder resist ink 200 and sufficiently spread on the solder resist ink 200. Specifically, wettability of the black ink 400 can be improved by adjusting an auxiliary having wettability in the black ink 400.

In one embodiment, referring to fig. 10 and 11, a shutter 800 is provided above the black matrix 310 to block the black matrix 310 when ink is ejected. In general, the solder resist ink 200, the black substrate 310 and the slit 500 are printed by an inkjet printer during the ink printing, but in the embodiment of the application, the shielding member 800 is disposed above the black substrate 310, and the black substrate 310 is shielded by the shielding member 800, so that the effect of the light emitting chip 330 being affected by the black ink 400 being sprayed on the light emitting chip 330 can be avoided.

In one embodiment, referring to fig. 10, the projection profile of the shielding member 800 on the black substrate 310 is located within a peripheral edge of the black substrate 310 and is located outside each of the light emitting chips 330, that is, the shielding member 800 completely shields the light emitting chips 330 on the black substrate 310, but does not completely shield the black substrate 310, and the shielding member 800 exposes a peripheral edge of the black substrate 310, so that the black ink 400 is sprayed onto the peripheral edge of the black substrate 310 during ink spraying.

Alternatively, the black matrix 310 has a square shape and the shutter 800 has a square shape, and the side length b of the black matrix 310 is larger than the side length c of the shutter 800. It will be appreciated that in other embodiments of the application, the shape of the shield 800 may also be adapted when the black substrate 310 is rectangular, circular or otherwise.

In one embodiment, referring to FIG. 11, the thickness of black ink 400 on solder mask ink 200 is greater than the height of black substrate 310 above solder mask ink 200; the black ink 400 covers a peripheral edge of the black substrate 310. That is, after the ink is ejected, the upper surface of the black ink 400 is higher than the upper surface of the black substrate 310, and the black ink 400 is covered on the peripheral edge of the upper surface of the black substrate 310, so that when the black ink 400 on the solder mask ink 200 is lower than the black ink 400 on the black substrate 310, the black ink 400 on the black substrate 310 flows to the solder mask ink 200, thereby ensuring that the black ink 400 on the black substrate 310 is uniformly distributed and improving the black consistency of the whole LED display module.

In one embodiment, referring to fig. 11, the width of the black ink 400 covering a peripheral edge of the black substrate 310 is less than 10um, so that the influence of the black ink 400 on the light emitting performance of the light emitting chip 330 can be reduced as much as possible.

Where necessary, the width of the black ink 400 on the black substrate 310 refers to the width from the outer edge to the inner edge of the black ink 400 on the black substrate 310.

In one embodiment, referring to fig. 11, the thickness of the black ink 400 on the black substrate 310 is less than 10um, so that the influence of the black ink 400 on the light emitting performance of the light emitting chip 330 can be reduced as much as possible.

In one embodiment, referring to FIG. 11, black ink 400 covers a peripheral edge of black substrate 310 less than 10um in width; and the thickness of the black ink 400 on the black substrate 310 is less than 10um.

In one embodiment, the ink may be sprayed to a predetermined thickness at a time or may be sprayed to a predetermined thickness several times and cured by ultraviolet light after spraying, at which time the black ink 400 may be selected as a material capable of being cured by ultraviolet light. Among them, the conditions of ultraviolet light curing may depend on the properties of the black ink 400.

In one embodiment, the ink can be cured while being sprayed to reduce the difficulty of the ink spraying process.

Referring to fig. 8, an LED display module after ink jet is shown, wherein except for the light emitting chip 330, only the black substrate 310 and the black ink 400 can be seen on the surface of the LED display module, and then a packaging process, a dicing process and other post-treatment processes are performed to obtain a high-contrast LED display module.

In one embodiment, the method for manufacturing the LED display module further includes the following steps:

s40: referring to fig. 12, the black substrate 310 and the black ink 400 are encapsulated by an encapsulation material to form an encapsulation layer 600.

In one embodiment, the packaging material may be a conventional packaging material such as epoxy resin, silicone, polymethyl methacrylate, thermoplastic such as polyurethane, ethylene-vinyl acetate copolymer, or transparent material such as OCA optical cement. The packaging process can be a lamination process such as mould pressing, hot pressing, vacuum pressing and the like.

In one embodiment, the surface of the encapsulation layer 600 may be a special functional surface obtained by using magnetron sputtering, vapor deposition, inkjet printing, or other processes, or may be a surface-mounted optical film to obtain different optical and physical properties. Preferably a surface-mounted optical film, more preferably an antireflective film (AR film) with an antireflective coating. The transmittance of the AR film material is more than 94%, and the reflectivity is less than 1%; preferably, the transmittance is more than 96% and the reflectance is less than 0.5%.

In the present application, the inkjet plate 2000 using the pixel unit 300 and the bottom inkjet has high blackness, and the AR film can reduce the reflection on the surface of the film material, so that the blackness is high when the whole LED display module is blacked out. Meanwhile, the AR film has high transmittance, and the brightness of the LED display module can be increased when the LED display module is white. Therefore, the whole LED display module has high contrast ratio.

In one embodiment, the LED display screen is formed by connecting the LED display modules through a box body and electric signals.

In another embodiment of the present application, referring to fig. 13 and 14, after the ink is ejected, the thickness of the black ink 400 on the solder resist ink 200 is smaller than the height of the black substrate 310 higher than the solder resist ink 200; the black ink 400 covers a peripheral edge of the black substrate 310. That is, after ink jetting, the upper surface of the black ink 400 on the solder mask ink 200 is lower than the upper surface of the black substrate 310, and the peripheral edge of the upper surface of the black substrate 310 is covered with the black ink 400, so that on one hand, the black ink 400 on the black substrate 310 has enough amount, so that the black ink 400 has enough tension, so that the black ink 400 on the black substrate 310 cannot flow onto the solder mask ink 200, the uniformity of the black ink 400 on the black substrate 310 is ensured, and the black uniformity of the whole LED display module is improved; in addition, the ink jet thickness of the black ink 400 on the solder resist ink 200 can be reduced, and the ink jet time and consumption of the black ink 400 can be reduced, so that the manufacturing cost can be effectively saved while the contrast is improved.

In still another embodiment of the present application, referring to fig. 15, before ink jetting, a transparent oleophobic layer 700 is formed on the front surface of the black matrix 310, and the oleophobic layer 700 at least covers each light emitting chip 330. That is, when the pixel unit 300 is manufactured, the oil-repellent layer 700 is formed on the front surface of the black substrate 310, and the oil-repellent layer 700 has low surface energy, so that the black ink 400 is prevented from covering the front surface of the black substrate 310, at least the black ink 400 is prevented from covering the light emitting chip 330. In other words, by the design of the oleophobic layer 700, it is possible to dispense with the shielding member 800 provided above the black matrix 310, and also to dispense with the need for the dimensional accuracy of the shielding member 800, and also to reduce the risk of ink ejection to the light emitting chip 330.

In one embodiment, oleophobic layer 700 can be a coating with reactive silane or fluorine modified organic groups, with the particular use of the coating being determined by the nature of black ink 400. The size of the oleophobic layer 700 is larger than the size of the light emitting chip 330, i.e., the oleophobic layer 700 covers at least the light emitting chip 330. The oleophobic layer 700 may be formed by spraying, magnetron sputtering, vapor deposition, etc., or may be formed during the production of the pixel cell 300.

Referring to fig. 7, the present application further provides an LED display module, which is manufactured by the manufacturing direction of the LED display module. The LED display module comprises a PCB 100, a pixel unit 300 and black ink 400; wherein, a layer of solder resist ink 200 is formed on the front surface of the PCB 100, and the solder resist ink 200 is formed with a window 210 to expose the bonding pad 110 on the PCB 100; the pixel unit 300 includes a black substrate 310, a plurality of light emitting chips 330 encapsulated on the front surface of the black substrate 310, and bonding pads 320 formed on the back surface of the black substrate 310; the fillets 320 of the pixel unit 300 are correspondingly welded on the bonding pads 110; the projection contour of the black substrate 310 on the PCB board 100 is located in the window 210, and a gap 500 is formed between the black substrate 310, the solder resist ink 200 and the bonding pad 110; the black ink 400 is formed on the solder resist ink 200 and fills in the gaps 500.

The LED display module provided by the embodiment of the application has high blackness, high black consistency and high contrast, and the LED display module has few defects such as cold joint and the like.

In addition, the application also provides an LED display screen which comprises a plurality of LED display modules, a box body and a circuit structure, wherein the LED display modules are respectively arranged on the box body and mutually spliced, and the circuit structure is respectively and electrically connected with the LED display modules.

The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims (10)

1. The manufacturing method of the LED display module is characterized by comprising the following steps of:

providing a PCB, wherein a layer of solder resist ink is formed on the front surface of the PCB, and a window is formed in the solder resist ink to expose a bonding pad on the PCB;

the method comprises the steps of fixing a crystal, and providing a pixel unit, wherein the pixel unit comprises a black substrate, a plurality of light emitting chips packaged on the front surface of the black substrate and welding pins formed on the back surface of the black substrate; correspondingly welding the welding pins on the welding pads; the projection outline of the black substrate on the PCB is positioned in the window, and gaps are formed among the black substrate, the solder resist ink and the bonding pads;

and (3) ink-jetting, namely spraying black ink in the solder resist ink and the gaps.

2. The method of claim 1, wherein the black ink has a blackness greater than that of the solder resist ink.

3. The method of manufacturing an LED display module according to claim 1, wherein a shielding member is provided above the black substrate to shield the black substrate when ink is ejected.

4. The method of claim 3, wherein a projection contour of the shielding member on the black substrate is located within a peripheral edge of the black substrate and surrounds each of the light emitting chips.

5. The method of manufacturing an LED display module according to claim 4, wherein the thickness of the black ink on the solder resist ink after the ink is ejected is greater than the height of the black substrate higher than the solder resist ink; the black ink covers a peripheral edge of the black substrate.

6. The method of manufacturing an LED display module according to claim 4, wherein the thickness of the black ink on the solder resist ink after the ink is ejected is smaller than the height of the black substrate higher than the solder resist ink; the black ink covers a peripheral edge of the black substrate.

7. The method of manufacturing an LED display module according to claim 5 or 6, wherein the black ink covers a peripheral edge of the black substrate with a width of less than 10um;

and/or, the thickness of the black ink covering a peripheral edge of the black substrate is less than 10um.

8. The method of manufacturing an LED display module according to claim 1 or 2, wherein a transparent oil-repellent layer is formed on the front surface of the black substrate before the ink is ejected, and the oil-repellent layer covers at least each of the light emitting chips.

9. An LED display module, characterized in that it is manufactured by the manufacturing method of the LED display module according to any one of claims 1 to 8;

the LED display module includes:

the PCB is provided with a layer of solder resist ink on the front surface, and the solder resist ink is provided with a window to expose a bonding pad on the PCB;

the pixel unit comprises a black substrate, a plurality of light emitting chips packaged on the front surface of the black substrate and welding pins formed on the back surface of the black substrate; the welding leg is welded on the welding pad; the projection outline of the black substrate on the PCB is positioned in the window, and gaps are formed among the black substrate, the solder resist ink and the bonding pads;

and black ink formed on the solder resist ink and filled in the gaps.

10. An LED display screen comprising the LED display module of claim 9.