LED unit plate, preparation method thereof and LED display screen

Abstract

The invention relates to the technical field of LED display, solves the technical problems of high cost and insufficient air tightness protection of an LED unit plate in the prior art, and provides an LED unit plate, a preparation method thereof and an LED display screen. The LED unit board comprises a circuit board which is provided with a light-emitting surface provided with an LED chip and a backlight surface provided with a plurality of electronic components; the via holes are formed in the circuit board, and conductive layers are arranged on the hole surfaces of the via holes, so that the LED chips are electrically conducted with the electronic components; the emergent light sealing layer is arranged on the emergent light surface and is used for sealing the LED chip; and the backlight sealing layer is arranged on the backlight surface and is used for sealing the electronic component. The LED unit plate and the preparation method thereof have the advantages that the cost can be reduced, and high-airtightness protection is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of LED display, and in particular to an LED unit board and a preparation method thereof, and an LED display screen. Background Art

[0002] At present, LED unit boards used in LED display screens generally use PCB boards with a 4-layer circuit design, and only the light-emitting surface of the PCB board, where a light-emitting chip such as an LED chip is set, is sealed with glue, thereby sealing the light-emitting surface to provide airtight protection. However, the existing LED unit boards have at least two shortcomings. On the one hand, the cost is relatively high due to the 4-layer circuit design of the PCB board; and on the other hand, only the light-emitting surface of the PCB board is sealed with glue, but no sealing means is taken for the backlight surface of the PCB board that is opposite to the light-emitting surface and is set with multiple electronic components such as ICs, resulting in a lack of sealing on the backlight surface and even the LED unit board, resulting in insufficient airtight protection.

[0003] Therefore, there is an urgent need to provide an LED unit board and a preparation method thereof that can reduce costs and have very high airtight protection. Summary of the invention

[0004] The present invention aims at the defects of the existing LED unit boards in the above-mentioned prior art, such as high cost and insufficient airtight protection. To achieve one purpose of the present invention, a LED unit board is provided, comprising: a circuit board, which has a light-emitting surface for arranging an LED chip and a backlight surface for arranging a plurality of electronic components; a plurality of vias arranged in the circuit board, wherein the hole surfaces of the vias are provided with a conductive layer so as to electrically conduct the LED chip with the electronic components; a light-emitting sealing layer arranged on the light-emitting surface, for sealing the LED chip; and a backlight sealing layer arranged on the backlight surface, for sealing the electronic components.

[0005] Furthermore, the light-emitting sealing layer is made of the first sealing material or the second sealing material and the adhesive film sequentially stacked on the light-emitting surface, and the backlight sealing layer is made of the first sealing material, the second sealing material or quick-drying packaging glue.

[0006] Furthermore, the first sealing material includes evenly mixed epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% of melanin by mass and 1% to 3% of diffusion powder by mass, the second sealing material includes evenly mixed epoxy glue GH1010A glue and epoxy glue GH1010B glue, the adhesive film includes a laminated acrylic resin layer, a PET film layer and an optical material processing layer, and the optical material processing layer is relatively farthest from the light emitting surface, and the quick-drying packaging glue is an epoxy resin glue.

[0007] To achieve another object of the present invention, a method for preparing an LED unit board is provided, comprising the following steps: S10: providing a circuit board having a light-emitting surface and a backlight surface, wherein a plurality of via holes are arranged in the circuit board, and a conductive layer for electrically connecting the LED chip and the electronic components is arranged on the hole surface of the via holes; S30: arranging the electronic components on the backlight surface, and arranging the LED chip on the light-emitting surface; S50: arranging the light-emitting sealing material and the backlight sealing material on the light-emitting surface and the backlight surface in sequence or simultaneously, thereby forming a light-emitting sealing layer and a backlight sealing layer on the light-emitting surface and the backlight surface, respectively; S70: curing the light-emitting sealing layer and the backlight sealing layer.

[0008] Further, step S50 includes: S51: providing a first sealing material that serves as both a light emitting sealing material and the above-mentioned backlight sealing material; S52: placing the circuit board in a glue injection mold; S53: injecting the first sealing material into the light emitting surface and the backlight surface at the same time, thereby respectively obtaining a light emitting sealing layer as a light emitting sealing layer and a backlight sealing layer as a backlight sealing layer; step S70 includes: S71: heating the light emitting sealing layer and the backlight sealing layer at 100°C to 120°C and curing them for 3 to 5 minutes; S72: heating the light emitting sealing layer and the backlight sealing layer at 130°C to 180°C and curing them for 3 to 5 hours.

[0009] Further, step S50 includes: S51: providing a second sealing material and a glue film as a light-emitting sealing material and a quick-drying sealing glue as a backlight sealing material; S52: placing the circuit board in a glue injection mold; S53: injecting the second sealing material to the light-emitting surface to form a light-emitting sealing layer, S54: pressing the glue film on the light-emitting sealing layer to obtain a glue film layer, and obtaining a light-emitting sealing layer including a stacked light-emitting sealing layer and a glue film layer; S55: applying the quick-drying sealing glue on the backlight surface at least 3 times to obtain a light-emitting sealing layer as a backlight sealing layer. The glue layer is coated with a layer of adhesive, and after each coating is completed, it is left to stand for 20 to 40 minutes before the next coating is performed; step S70 includes: S71: heating the light-emitting sealing glue layer at 100°C to 120°C and curing it for 3 to 5 minutes; S72: heating the light-emitting sealing glue layer at 130°C to 180°C and curing it for 3 to 5 hours; S73: curing the adhesive film layer with UV light for 1 to 3 minutes and then vacuuming it for 25 to 35 minutes to obtain an adhesive film layer with a thickness of 200 to 300 μm; S74: leaving the glue layer to stand at room temperature for 12 to 15 hours.

[0010] Further, step S50 includes: S51: providing a film as a light-emitting sealing material and a quick-drying encapsulation glue as a backlight sealing material; S52: pressing the film on the light-emitting surface to obtain a film layer as a light-emitting sealing layer; S53: applying the quick-drying encapsulation glue on the backlight surface at least 3 times to obtain a glue layer as a backlight sealing layer, and after each application, leaving it to stand for 20 to 40 minutes before the next application; step S70 includes: S71: curing the film layer with UV light for 1 to 3 minutes and then evacuating it for 25 to 35 minutes to obtain a film layer with a thickness of 200 to 300 μm; S72: leaving the glue layer to stand at room temperature for 12 to 15 hours.

[0011] Further, step S10 includes providing a glass-based circuit board as the circuit board, and the glass-based circuit board has a process edge; the preparation method also includes: S41: providing a receiving mold, the receiving mold includes a bottom mold surface and a vertical mold surface surrounding the edge of the bottom mold surface, and a glue injection port is opened on the vertical mold surface; S42: running the glass-based circuit board into the receiving mold through the process edge, so that each side surface of the glass-based circuit board is sealed against the vertical mold surface, and there is a gap between the backlight surface of the glass-based circuit board and the bottom surface of the receiving mold, and the glue injection port is connected to the gap; S43: removing the process edge on the glass-based circuit board; step S50 includes: S51: providing a first sealing material or a film as a light emitting sealing material, and providing a second sealing material as a backlight sealing material; S52: injecting the first sealing material into the light emitting surface to obtain a first light emitting sealing layer as a light emitting sealing layer; or, pressing the film on the light emitting surface to obtain a film layer as a light emitting sealing layer;

[0012] S53: Filling the gap with a second sealing material serving as a backlight sealing material through the injection port to form a backlight sealing layer on the backlight surface; S54: Inverting the glass-based circuit board and the accommodating mold, and then lifting the accommodating mold to be relatively away from the glass-based circuit board; Step S70 includes: S71: heating and curing the first light-emitting sealing layer at 100℃~120℃ for 3~5min, and then heating and curing the first light-emitting sealing layer at 130℃~180℃ for 3~5h, or, curing the film layer with UV light for 1~3 minutes and then evacuating for 25~35min to obtain a film layer with a thickness of 200~300μm; S72: heating and curing the backlight sealing layer at 100℃~120℃ for 3~5min, and then heating and curing the backlight sealing layer at 130℃~180℃ for 3~5h.

[0013] Furthermore, the first sealing material includes uniformly mixed epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% by mass of melanin and 1% to 3% by mass of diffusion powder;

[0014] Furthermore, the adhesive film includes an acrylic resin layer, a PET film layer and an optical material processing layer which are stacked, and the optical material processing layer is relatively farthest from the light emitting surface; the second sealing material is prepared by uniformly mixing epoxy glue GH1010A glue and epoxy glue GH1010B glue.

[0015] To achieve another purpose of the present invention, an LED display screen is provided, which includes at least one LED display module, each LED display module includes an LED unit board, and the LED unit board is the LED unit board described in any of the preceding items, or the LED unit board is prepared by the preparation method of the LED unit board described in any of the preceding items.

[0016] The beneficial effects of the present invention are:

[0017] The LED unit board and preparation method thereof of the present invention realize a two-layer circuit design of the circuit board by respectively arranging LED chips and electronic components on the light-emitting surface and the backlight surface, thereby reducing costs. In addition, the light-emitting surface and the backlight surface of the circuit board are double-sided sealed to provide a high airtightness protection effect for the LED chips and electronic components on each surface, and are also beneficial to prolonging the service life of the LED unit board and the LED display module and LED screen to which it is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for use in the embodiment of the present invention will be briefly introduced below. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work, and these are all within the protection scope of the present invention.

[0019] Figure 1 A schematic diagram of the structure of an LED unit board embodiment provided by the present invention when a light-emitting sealing layer and a backlight sealing layer are not arranged;

[0020] Figure 2 A structural schematic diagram of a method for preparing an LED unit board provided by the present invention when a glue injection mold is arranged on the LED unit board in the first embodiment;

[0021] Figure 3 A schematic diagram of the structure of an LED unit board prepared by each LED unit board preparation method embodiment provided by the present invention;

[0022] Figure 4 A schematic diagram of the overall process of the method for preparing the LED unit board provided by the invention;

[0023] Figure 5 A schematic diagram of the arrangement of the LED chips in an LED display module of an LED unit board provided by the invention;

[0024] Figure 6 A schematic flow chart of a first embodiment of a method for preparing an LED unit board provided by the invention;

[0025] Figure 7 A schematic flow chart of a second embodiment of a method for preparing an LED unit board provided by the invention;

[0026] Figure 8 A schematic flow chart of a third embodiment of a method for preparing an LED unit board provided by the invention;

[0027] Fig. 9 A schematic flow chart of a fourth embodiment of a method for preparing an LED unit board provided by the invention;

[0028] Description of reference numerals:

[0029] 1-circuit board; 2-LED chip; 3-electronic components; 4-conducting hole; 5-light-emitting sealing layer; 6-backlight sealing layer; 7-upper mold edge; 8-lower mold edge. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described in conjunction with the drawings in the embodiment of the present invention. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In the description of the present invention, it should be understood that the orientation or position relationship indicated by the terms "inverted", "up", "down", "front", "back", "horizontal", "vertical", "top", "bottom", "inside", "outside", "rise", "fall" and the like is based on the orientation or position relationship shown in the drawings, which 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, and therefore cannot be understood as a limitation of the present invention. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or device. In the absence of further restrictions, the elements defined by the phrase "comprising..." do not exclude the existence of other identical elements in the process, method, article or device comprising the elements. If there is no conflict, the embodiments of the present invention and the various features in the embodiments can be combined with each other and are all within the protection scope of the present invention.

[0031] refer to Figures 1 to 3, Figure 5 As an object of the present invention, an LED unit board is provided, which includes a circuit board, a plurality of vias, a light-emitting sealing layer and a backlight sealing layer. The circuit board has a light-emitting surface on which an LED chip is arranged, which may also be referred to as an LED surface, and a backlight surface on which a plurality of electronic components are arranged, which may also be referred to as an IC surface. The circuit board may be, for example, a glass-based circuit board, a PCB board, a silicon-based circuit board, etc. Circuit layers electrically connected to the LED chip and the electronic components are provided on both the light-emitting surface and the backlight surface. A plurality of vias are provided in the circuit board, and the hole surface, i.e., the hole wall, of the via is provided with a copper conductive layer by, for example, copper electroplating, so that the LED chip is electrically connected to each electronic component; the light-emitting sealing layer is provided on the light-emitting surface, so as to seal the LED chip, and the backlight sealing layer is provided on the backlight surface, so as to seal the electronic components. In this case, the circuit board adopts a two-layer circuit design to reduce costs. In addition, the light-emitting surface and backlight surface of the circuit board are double-sided sealed to provide a highly airtight protection effect for the LED chips and electronic components on each surface, which is beneficial to extend the service life of the LED unit board and the LED display module and LED screen to which it is applied.

[0032] Specifically, the light-emitting sealing layer is made of a first sealing material or a film or a second sealing material and a film sequentially stacked on the light-emitting surface, and the backlight sealing layer is made of a first sealing material, a second sealing material or a quick-drying sealing glue. In this way, the sealing material, the film and the quick-drying sealing glue can selectively obtain reliable and high airtight protection for the light-emitting surface and the backlight surface.

[0033] Specifically, the first sealing material includes uniformly mixed epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% by mass of melanin and 1% to 3% by mass of diffusion powder, wherein the main component of the melanin is carbon powder, and the main component of the diffusion powder is light diffusing agent and ethylene bisstearamide. The second sealing material includes epoxy glue GH1010A glue and epoxy glue GH1010B glue that are evenly mixed. In addition, for the epoxy glue GH1010A glue and epoxy glue GH1010 B glue in the first sealing material and the second sealing material, their mass percentages can be selected and adjusted between 1:1 and 10:1. The adhesive film includes a laminated acrylic resin layer, a PET film layer and an optical material processing layer, and the optical material processing layer is relatively farthest from the light emitting surface, that is, the acrylic resin layer serves as the LED chip contact layer, the PET film layer serves as the middle layer, and the optical material processing layer serves as the glue surface layer. The quick-drying packaging glue is an epoxy resin glue. After repeated experiments by the applicant, and in combination with reference to Table 1 below, the components and mass percentages of the sealing material can be further determined according to the light output rate of the screen determined when the product development sample is developed, and when the sealing material and the film layer are set to the above-mentioned specific situations, the expected excellent airtight protection effect can be obtained.

[0034] As another object of the present invention, in conjunction with reference Figure 4 The present invention also provides a method for preparing an LED unit board. In the absence of conflict, the preparation method described below is correspondingly applicable to the LED unit boards of the above embodiments, and the relevant repeated contents are not repeated here. The preparation method comprises the following steps:

[0035] S10: Provide a circuit board with a light emitting surface and a backlight surface. A plurality of via holes can be set in the circuit board by mechanical drilling. A conductive layer such as a copper-plated layer is set on the surface of the via holes. The conductive layer electrically connects the LED chip with the electronic components.

[0036] S30: soldering electronic components on the backlight surface, for example, by SMT process, for example, transferring the LED chip to the light emitting surface by a transfer device, and in addition, the LED chips may be four, and the RGBG LED chips are arranged in a rectangular form on the light emitting surface. Figure 5 The arrangement of LED chips R, LED chips G, LED chips B and LED chips G of each LED unit board on an LED display module is shown.

[0037] S50: Arrange the light emitting sealing material and the backlight sealing material on the light emitting surface and the backlight surface in a sequential order or simultaneously, so as to form a light emitting sealing layer and a backlight sealing layer on the light emitting surface and the backlight surface respectively. The sequential order or simultaneous order can be determined according to different situations such as the surface area of ​​the circuit board, the number of LED chips and electronic components, the conditions of the preparation equipment, and the preparation materials.

[0038] S70: performing a curing process on the light-emitting sealing layer and the backlight sealing layer, for example, using UV light.

[0039] Therefore, by adopting the preparation method of the LED unit board of the present invention, not only can a light-emitting surface and a backlight surface be formed on the two back sides of the circuit board, but also the LED chip on the light-emitting surface and the electronic components on the backlight surface can be electrically connected by using the conducting holes with a conductive layer provided in the circuit board, thereby realizing a two-layer circuit design and achieving the purpose of reducing costs. Moreover, a sealing material is used to seal both the light-emitting surface and the backlight surface, so that the two opposite sides of the LED unit board both obtain a very high airtight protection effect.

[0040] Please refer to Figure 6 As a first embodiment of the method for preparing the LED unit board of the present invention, specifically, step S50 includes:

[0041] S51: providing a first sealing material that serves as both a light-emitting sealing material and a backlight sealing material,

[0042] S52: placing the circuit board in the injection mold;

[0043] S53: injecting the first sealing material to the light emitting surface and the backlight surface at the same time, which can be specifically implemented by using a molding device with an upper injection port and a lower injection port, the molding device is provided with a storage container for storing the first sealing material, and accordingly, the above-mentioned injection mold is a mold that satisfies the upper and lower injections, the injection mold comprises an upper mold edge surrounding the area where the first sealing material needs to be injected on the light emitting surface and a lower mold edge surrounding the area where the first sealing material needs to be injected on the backlight surface, the upper mold edge and the lower mold edge form an upper glue inlet and a lower glue inlet, the respective heights of the upper mold edge and the lower mold edge are respectively greater than the respective thicknesses of the light emitting sealing layer and the backlight sealing layer, the upper injection port and the lower injection port simultaneously inject the first sealing material from the storage container toward the light emitting surface and the backlight surface respectively, thereby obtaining a light emitting sealing layer as a light emitting sealing layer and a backlight sealing layer as a backlight sealing layer, respectively.

[0044] Step S70 includes:

[0045] S71: heating the light-emitting sealant layer and the backlight sealant layer at 100° C. to 120° C. and curing for 3 to 5 minutes;

[0046] S72: The light-emitting sealant layer and the backlight sealant layer are heated at 130° C. to 180° C. and cured for 3 to 5 hours.

[0047] As described above, for the first embodiment of the preparation method of the LED unit board, since the first sealing material is injected into the light-emitting surface and the backlight surface at the same time, it is particularly suitable for the situation where the surface area of ​​the light-emitting surface and the backlight surface is relatively large, thereby significantly improving the injection efficiency and the curing efficiency, and is beneficial to ensure the consistency of the thickness, air tightness, etc. of the light-emitting sealing layer and the backlight sealing layer.

[0048] Please refer to Figure 7 As a second embodiment of the method for preparing an LED unit board of the present invention, the contents that are the same or similar to those of the first embodiment can be obtained by reference and will not be repeated here. Specifically, step S50 includes:

[0049] S51: providing a second sealing glue material and a glue film as a light-emitting sealing material and a quick-drying packaging glue as a backlight sealing material.

[0050] S52: Place the circuit board in the injection mold.

[0051] S53: injecting a second sealing material into the light emitting surface to form a light emitting sealing layer with a thickness of 200 to 500 μm. Specifically, a molding device with an upper injection port is used, and the injection mold is a mold with an upper injection port. The second sealing material is injected into the light emitting surface through the upper injection port.

[0052] S54: For example, a roller is used to press a glue film on the light-emitting sealant layer to obtain a glue film layer, so that the light-emitting sealing layer includes a stacked light-emitting sealant layer and a glue film layer.

[0053] S55: Apply quick-drying encapsulation glue on the backlight surface at least 3 times and preferably no more than 5 times to obtain a glue layer as a backlight sealing layer, and let it stand for 20 to 40 minutes after each application before the next application. The application can be applied with an artificial brush;

[0054] Step S70 includes:

[0055] S71: heating the light-emitting sealant layer at 100° C. to 120° C. and curing for 3 to 5 minutes;

[0056] S72: heating the light-emitting sealant layer at 130° C. to 180° C. and curing for 3 to 5 hours;

[0057] S73: UVA light exposure to the film layer is 365nn and 6000MJ / cm 2 The standard UV light is cured for 1 to 3 minutes, and then vacuumed for 25 to 35 minutes to obtain a film layer with a thickness of 200 to 300 μm;

[0058] S74: The glue layer is left to stand at room temperature for 12 to 15 hours, and the room temperature may specifically be 25±5°C.

[0059] As described above, compared with the first embodiment of the preparation method of the LED unit board, in the second embodiment, since a glue film is also pressed on the light-emitting sealing layer, it can not only improve the overall wear resistance of the light-emitting sealing layer but also improve the tightness of the fit between the light-emitting sealing layer and the light-emitting surface. Moreover, since quick-drying packaging glue is applied on the backlight surface, the backlight surface does not need to be thermally cured, which is particularly suitable for situations where electronic components that are sensitive to temperature are used.

[0060] Please refer to Figure 8 As the third embodiment of the method for preparing the LED unit board of the present invention, the contents identical or similar to those of the first and second embodiments above can be obtained by reference and will not be repeated here. Specifically, step S50 includes:

[0061] S51: providing a film as a light-emitting sealing material and a quick-drying packaging glue as a backlight sealing material;

[0062] S52: Laminating an adhesive film on the light-emitting cover to obtain an adhesive film layer serving as a light-emitting sealing layer;

[0063] S53: Apply quick-drying encapsulation glue on the backlight surface at least 3 times and preferably no more than 5 times to obtain a glue layer as a backlight sealing layer, and let it stand for 20 to 40 minutes after each application before applying the next time.

[0064] Step S70 includes:

[0065] S71: The film layer is subjected to 365 nn and 6000 MJ / cm 2 After UV curing for 1 to 3 minutes, vacuum is drawn for 25 to 35 minutes to obtain a film layer with a thickness of 200 to 300 μm.

[0066] S72: Leave the glue layer to stand at room temperature for 12 to 15 hours.

[0067] As described above, compared with the first and second embodiments of the preparation method of the LED unit board, in the third embodiment, since the adhesive film is directly pressed on the light-emitting surface, the sealing step is omitted, the preparation efficiency is improved, and quick-drying packaging glue is applied on the backlight surface, so that neither the light-emitting surface nor the backlight surface requires heat curing treatment, which not only further improves the preparation efficiency, but also further enhances the applicability to electronic components that are more sensitive to temperature.

[0068] Please refer to Fig. 9, as the fourth embodiment of the method for preparing the LED unit board of the present invention, the contents that are the same or similar to the above first to third embodiments can be obtained by reference, and will not be repeated here. Specifically, step S10 includes providing a glass-based circuit board as a circuit board, the glass-based circuit board has a process edge, and the process edge is specifically arranged in the area outside the pad when the LED chip is fixed to the light-emitting surface by welding. The process edge can be used by the transfer equipment to transfer the circuit board on its track to the accommodating mold (not shown). In addition, the transfer equipment used for mass transfer occasions can also be applicable.

[0069] The method for preparing the LED unit board also includes:

[0070] S41: providing a receiving mold, the receiving mold comprising a bottom mold surface and a vertical mold surface surrounding an edge of the bottom mold surface, and a glue injection port is provided on the vertical mold surface.

[0071] S42: For example, a transfer device is used to transfer the glass-based circuit board to the receiving mold through the process edge, so that the side surfaces of the glass-based circuit board are sealed against the vertical mold surface, so that the first sealing material and the second sealing material will not leak between the glass-based circuit board and the receiving mold, and there is a gap between the backlight surface of the glass-based circuit board and the bottom surface of the receiving mold, and the glue injection port is connected to the gap.

[0072] S43: removing the process edge on the glass-based circuit board. In this way, after the glass-based circuit board is transferred, in order to prevent the process edge from interfering with the subsequent use of the LED unit board for splicing LED display modules, the process edge needs to be removed by, for example, cutting.

[0073] Step S50 includes:

[0074] S51: providing a first sealing material or a film as a light-emitting sealing material, and providing a second sealing material as a backlight sealing material.

[0075] S52: injecting a first sealing material onto the light emitting surface to obtain a first light emitting sealing layer as a light emitting sealing layer; or, laminating a glue film onto the light emitting surface to obtain a glue film layer as a light emitting sealing layer.

[0076] S53: filling the gap with a second sealing material as a backlight sealing material through the injection port to form a backlight sealing layer on the backlight surface, that is, the accommodating mold temporarily accommodates at least part of the glass-based circuit board and the backlight sealing layer.

[0077] S54: Invert the glass-based circuit board and the containing mold, and then lift the containing mold to be relatively away from the glass-based circuit board. By first inverting the glass-based circuit board and the containing mold so that the backlight sealing layer faces upward, when the containing mold is lifted away from the glass-based circuit board, under the action of the backlight sealing layer's own gravity and the surface adhesion force between the backlight sealing layer and the backlight surface, the backlight sealing layer maintains an intact layer shape when the containing mold is moved away.

[0078] Step S70 includes:

[0079] S71: Heat the first light-emitting sealant layer at 100°C-120°C and cure it for 3-5 minutes, then heat the first light-emitting sealant layer at 130°C-180°C and cure it for 3-5 hours, or, cure the film layer with UV light of, for example, 365nn and 6000MJ / cm2 for 1-3 minutes, and then evacuate for 25-35 minutes to obtain a film layer with a thickness of 200-300μm.

[0080] S72: The backlight sealing glue layer is heated at 100° C. to 120° C. and cured for 3 to 5 minutes, and then the backlight sealing glue layer is heated at 130° C. to 180° C. and cured for 3 to 5 hours.

[0081] As described above, compared with the first to third embodiments of the preparation method of the LED unit board, the fourth embodiment is particularly suitable for a glass-based circuit board as one of the circuit boards. In this case, for the glass-based circuit board, the preparation method of this embodiment utilizes a backlight sealing layer formed in the gap between the backlight surface and the bottom mold surface of the LED unit board, which can not only reliably obtain a backlight sealing layer with a precise thickness, thereby providing airtight protection for the backlight surface, but also prevent the glass substrate of the glass-based circuit board from being fragile.

[0082] As a preferred embodiment, the first sealing material includes epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% melanin by mass, and 1% to 3% diffusion powder by mass. For the adhesive film, it includes a laminated acrylic resin layer, a PET film layer, and an optical material processing layer. The optical material processing layer is relatively farthest from the light-emitting surface. The optical material processing layer is arranged in the adhesive film to improve the light-emitting effect. For the second sealing material, it is obtained by uniformly mixing epoxy glue GH1010A glue and epoxy glue GH1010 B glue. The mass percentages of epoxy glue GH1010 A glue and epoxy glue GH1010 B in the first sealing material and the second sealing material can be selected and adjusted between 1:1 and 10:1.

[0083] To further illustrate the beneficial technical effects of the present invention represented by the PCT test failure rate, based on the applicant's experiments, the following Table 1 lists the experimental data of the preparation method examples for the above-mentioned LED unit boards in combination with the preferred implementation methods.

[0084] Table 1: Experimental data comparison table of different LED unit board preparation methods

[0085]

[0086] Explanation of terms in Table 1 : Epoxy glue: mixed epoxy glue GH1010 A glue and epoxy glue GH1010 B; Adhesive film: laminated acrylic resin layer, PET film layer and optical material treatment layer; PCT experiment: airtightness verification experiment, the test conditions are 2 atmospheres, 100℃ boiling water, and boiling for 12h; Test the LED chip failure rate before and after the LED unit board experiment; ppm: one part per million.

[0087] According to Table 1 above, in Examples 1 to 4 of the method for preparing the LED unit board of the present invention and in combination with the preferred implementation mode, the PCT test failure rate is less than or equal to 5 ppm, that is to say, the failure rate of the LED chip is very low, so that the LED unit board has a high airtight protection effect.

[0088] Please refer to Figure 5 As another object of the present invention, an LED display module is provided, which includes a plurality of LED unit boards of any one of the above or LED unit boards prepared by any embodiment of the method for preparing the LED unit board and a bottom shell (not shown), the bottom shell is made of aluminum and is used to fix a plurality of LED unit boards together thereon to form an LED display module, each LED unit board is fixed on the bottom shell, and each LED unit board has four LED chips arranged in an RGBG rectangular form or LED chips arranged in an RGB manner. The LED display module can obtain the beneficial effects brought by any LED unit board, thereby having the advantages of reducing costs and high airtightness protection.

[0089] As another object of the present invention, an LED display screen is provided, which includes a plurality of LED display modules of any of the above types arranged in a spliced ​​manner. The LED display screen can obtain the beneficial effects brought by any of the LED display modules, thereby having the advantages of reducing costs and high airtightness protection.

[0090] Finally, it should be explained that the above-mentioned circuit board is specifically a thin plate body with a rectangular or square cross-section, the bottom mold surface of the accommodating mold is rectangular or square, and the vertical mold surface encloses a rectangular or cube cavity to accommodate the glass-based circuit board. In addition, the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above-mentioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above-mentioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An LED unit board, characterized in that: include: A circuit board having a light emitting surface on which an LED chip is arranged and a backlight surface on which a plurality of electronic components are arranged; A plurality of via holes are provided in the circuit board, and a conductive layer is provided on the hole surface of the via hole so as to electrically connect the LED chip with the electronic component; A light-emitting sealing layer is provided on the light-emitting surface, and is used to seal the LED chip; The backlight sealing layer arranged on the backlight surface is used to seal the electronic components.

2. The LED unit board according to claim 1, characterized in that: The light-emitting sealing layer is made of a first sealing material or a second sealing material and a film sequentially stacked on the light-emitting surface, and the backlight sealing layer is made of the first sealing material, the second sealing material or quick-drying packaging glue.

3. The LED unit board according to claim 2, characterized in that: The first sealing material includes evenly mixed epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% melanin by mass and 1% to 3% diffusion powder by mass; the second sealing material includes evenly mixed epoxy glue GH1010A glue and epoxy glue GH1010 B glue; the adhesive film includes a laminated acrylic resin layer, a PET film layer and an optical material processing layer, and the optical material processing layer is relatively farthest from the light emitting surface; the quick-drying packaging glue is an epoxy resin glue.

4. A method for preparing an LED unit board, characterized in that: The steps include: S10: providing a circuit board having a light emitting surface and a backlight surface, wherein a plurality of via holes are arranged in the circuit board, and a conductive layer for electrically connecting the LED chip and the electronic component is arranged on the hole surface of the via hole; S30: Arranging electronic components on the backlight surface and arranging LED chips on the light emitting surface; S50: arranging a light-emitting sealing material and a backlight sealing material on the light-emitting surface and the backlight surface in sequence or simultaneously, thereby forming a light-emitting sealing layer and a backlight sealing layer on the light-emitting surface and the backlight surface respectively; S70: curing the light-emitting sealing layer and the backlight sealing layer.

5. The method for preparing the LED unit board according to claim 4, characterized in that: The step S50 comprises: S51: providing a first sealing material that serves as both the light-emitting sealing material and the backlight sealing material; S52: placing the circuit board in a glue injection mold; S53: injecting the first sealing material to the light emitting surface and the backlight surface simultaneously, thereby obtaining a light emitting sealing layer as the light emitting sealing layer and a backlight sealing layer as the backlight sealing layer respectively; The step S70 includes: S71: heating the light-emitting sealant layer and the backlight sealant layer at 100° C. to 120° C. and curing them for 3 to 5 minutes; S72: The light-emitting sealant layer and the backlight sealant layer are heated at 130° C. to 180° C. and cured for 3 to 5 hours.

6. The method for preparing the LED unit board according to claim 4, characterized in that: The step S50 comprises: S51: providing a second sealing glue material and a glue film as a light-emitting sealing material and a quick-drying packaging glue as a backlight sealing material; S52: placing the circuit board in the injection mold; S53: injecting a second sealing material into the light emitting surface to form a light emitting sealing layer; S54: pressing the adhesive film on the light-emitting sealant layer to obtain an adhesive film layer, and obtaining the light-emitting sealing layer including the stacked light-emitting sealant layer and the adhesive film layer; S55: applying the quick-drying encapsulation glue on the backlight surface at least three times to obtain a glue layer as the backlight sealing layer, and leaving it to stand for 20 to 40 minutes after each application before applying the next one; The step S70 includes: S71: heating the light-emitting sealant layer at 100° C. to 120° C. and curing it for 3 to 5 minutes; S72: heating the light-emitting sealant layer at 130° C. to 180° C. and curing for 3 to 5 hours; S73: curing the adhesive film layer with UV light for 1 to 3 minutes and then evacuating the film layer for 25 to 35 minutes to obtain an adhesive film layer with a thickness of 200 to 300 μm; S74: Leave the glue layer to stand at room temperature for 12 to 15 hours.

7. The method for preparing the LED unit board according to claim 4, characterized in that: The step S50 comprises: S51: providing a film as a light-emitting sealing material and a quick-drying packaging glue as a backlight sealing material; S52: Laminating the adhesive film on the light emitting surface to obtain an adhesive film layer as the light emitting sealing layer; S53: applying the quick-drying encapsulation glue on the backlight surface at least three times to obtain a glue layer as the backlight sealing layer, and leaving it to stand for 20 to 40 minutes after each application before applying the next one; The step S70 includes: S71: curing the adhesive film layer with UV light for 1 to 3 minutes and then evacuating the film layer for 25 to 35 minutes to obtain an adhesive film layer with a thickness of 200 to 300 μm; S72: Leave the glue layer to stand at room temperature for 12 to 15 hours.

8. The method for preparing the LED unit board according to claim 4, characterized in that: The step S10 includes providing a glass-based circuit board as the circuit board, wherein the glass-based circuit board has a process edge; The preparation method further comprises: S41: providing a receiving mold, the receiving mold comprising a bottom mold surface and a vertical mold surface surrounding an edge of the bottom mold surface, and a glue injection port is provided on the vertical mold surface; S42: moving the glass-based circuit board into the receiving mold through the process edge, so that each side surface of the glass-based circuit board is sealed against the vertical mold surface, and there is a gap between the backlight surface of the glass-based circuit board and the bottom surface of the receiving mold, and the glue injection port is connected with the gap; S43: removing the process edge on the glass-based circuit board; The step S50 comprises: S51: providing a first sealing material or a film as a light-emitting sealing material, and providing a second sealing material as a backlight sealing material; S52: injecting the first sealing material onto the light emitting surface to obtain a first light emitting sealing layer as the light emitting sealing layer; or laminating the adhesive film onto the light emitting surface to obtain an adhesive film layer as the light emitting sealing layer; S53: filling a second sealing material as a backlight sealing material into the gap through the glue injection port to form a backlight sealing layer on the backlight surface; S54: inverting the glass-based circuit board and the receiving mold, and then lifting the receiving mold to be relatively away from the glass-based circuit board; The step S70 includes: S71: heating the first light-emitting sealant layer at 100° C. to 120° C. and curing it for 3 to 5 minutes, and then heating the first light-emitting sealant layer at 130° C. to 180° C. and curing it for 3 to 5 hours, or curing the film layer with UV light for 1 to 3 minutes and then vacuuming it for 25 to 35 minutes to obtain a film layer with a thickness of 200 to 300 μm; S72: heating the backlight sealant layer at 100° C. to 120° C. and curing it for 3 to 5 minutes, and then heating the backlight sealant layer at 130° C. to 180° C. and curing it for 3 to 5 hours.

9. The method for preparing the LED unit board according to claim 5 or 8, characterized in that: The first sealing material includes uniformly mixed epoxy glue GH1010A glue, epoxy glue GH1010 B glue, 3% to 8% by mass of melanin and 1% to 3% by mass of diffusion powder.

10. The method for preparing the LED unit board according to claim 6 or 8, characterized in that: The adhesive film includes an acrylic resin layer, a PET film layer and an optical material processing layer which are stacked, and the optical material processing layer is relatively farthest from the light emitting surface; the second sealing material is prepared by uniformly mixing epoxy glue GH1010A glue and epoxy glue GH1010 B glue.

11. An LED display screen, characterized in that: The LED display screen includes at least one LED display module, each LED display module includes an LED unit board, and the LED unit board is the LED unit board described in any one of claims 1 to 3, or the LED unit board is prepared by the preparation method of the LED unit board described in any one of claims 4-9.

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