Manufacturing Method of Micro & Mini Micro-Pitch LED Display Module

Abstract

The present invention discloses a manufacturing method for Micro&Mini micro-pitch LED display modules, comprising the following steps: preparing Micro&Mini micro-pitch LED display modules: first, perform batch pre-balling on a substrate; then perform batch flux printing on the substrate, and finally transfer MicroLEDs and bake them in a reflow oven to complete soldering; perform inkjet printing on the surface of the PCB with an interval between adjacent LED units to fix the LED chips, and then obtain RGB modules through cutting; prepare LED display screen modules; including the production of BOTTOM substrates and TOP substrates. The present invention uses the OnePixelStructure prepared by MicroPixelLED to transfer to the substrate in the most stable 1by1 manner, improving the process yield, and continuing to use the depreciated original fixed assets and streamlining the process flow to reduce manufacturing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of LED display, and particularly to a manufacturing method for Micro&Mini micro-pitch LED display modules. Background Art

[0002] An LED display screen is a new type of display method that directly emits light based on red, green, and blue chips to display graphics, and is widely used in the fields of professional display, commercial display, and public display. Micro-pitch is a high-end product of current LED display screens, with excellent characteristics such as self-luminescence, low power consumption, high brightness, high refresh rate, ultra-high resolution and color saturation, fast response, long lifespan, and seamless splicing. It has a display effect that surpasses LCD and OLED, and compared with traditional LED display screens, it has the advantage of clearer and more delicate image quality when viewed at close range, and is the current development direction of LED display screens.

[0003] At present, the main packaging forms of micro-pitch LED display screens are SMD (such as 0808, 0606, 0404), N-in-one (such as four-in-one, two-in-one), and the COB technical route. There are also two main research directions for substrates in the market: glass substrates and PCB boards. Micro-pitch LED display screens are a display technology that uses miniaturization and matrix technology. Currently, they are restricted by technical bottlenecks such as accuracy, yield, efficiency, and cost, and are mainly used in professional displays. With the rapid development of technologies such as microchips and mass transfer, the cost has been further reduced, and the civilian market is rapidly opening up. Summary of the Invention

[0004] The object of the present invention is to solve the problems in the above background art, and propose a manufacturing method for Micro&Mini micro-pitch LED display modules.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A manufacturing method for Micro&Mini micro-pitch LED display modules, comprising the following steps:

[0007] Step 1: Prepare a Micro&Mini micro-pitch (less than P0.5) LED display module:

[0008] First, perform batch pre-balling on the substrate; then perform batch flux printing on the substrate, and finally transfer the Micro LED and bake it in a reflow oven to complete welding;

[0009] Perform printing on the surface of the PCB with an interval between adjacent LED units to fix the LED chips, and then obtain an RGB module through cutting;

[0010] Among them, ball planting: Make a silk screen. According to the pad positions and shapes on the MEP substrate, make a silk screen for stenciling solder paste. Under the action of a squeegee, evenly coat the solder on each pad, and then place it in a reflow oven for baking to complete ball planting;

[0011] Printing: Make a silk screen. According to the ball positions and shapes on the MEP substrate, make the silk screen holes for stenciling flux. Under the action of a squeegee, evenly coat the flux on each pad;

[0012] Step 2, prepare the LED display module; including the production of the BOTTOM substrate and the TOP substrate.

[0013] As a further solution of the present invention: In step 1, before ball planting, complete the processes of MEP substrate cutting, cleaning, dehumidification, calibration, and mark processing.

[0014] As a further solution of the present invention: Cutting: Use a dicing saw to evenly divide the MEP substrate with a size of 240mm * 75mm, and cut it into 120mm * 75mm.

[0015] As a further solution of the present invention: Calibration: Through a leveling tooling, level the cleaned MEP substrate, and the warpage is <0.5%.

[0016] As a further solution of the present invention: The specific process of BOTTOM substrate production is as follows:

[0017] Make a silk screen for stenciling solder paste according to the pad positions and shapes on the lamp board;

[0018] Put the IC and resistor-capacitor components into the corresponding positions on the BOT surface of the lamp board through a mounter, and then put it into a reflow oven for baking to complete soldering.

[0019] As a further solution of the present invention: The specific process of TOP substrate production is as follows:

[0020] Make a silk screen for stenciling solder paste according to the pad positions and shapes on the semi-finished lamp board;

[0021] Put the RGB module into the corresponding positions on the TOP surface of the lamp board through a mounter. The lamp board is placed in advance in the tooling for RGB module splicing, and then put it into a reflow oven for baking to complete soldering;

[0022] Perform a surface super-black nano-coating through a coating machine.

[0023] The beneficial effects of the present invention:

[0024] The One Pixel Structure prepared by the present invention using Micro Pixel LED is transferred to the substrate in the most stable 1by1 manner, improving the process yield. The original fixed assets are continued to be depreciated and the process flow is streamlined to reduce the manufacturing cost.

[0025] The present invention adopts an MEP (Moulded Embedded Package) substrate with an embedded IC to solve the problem that the backside IC devices cannot be arranged in a super-small pitch, explore the physical limit of PCB-based LED displays, and accelerate the trend of the civilian market for micro-pitch LED displays.

[0026] The present invention combines the ball mounting process in the field of microelectronics technology. First, ball mounting is completed in batches on the substrate. Then, batch flux printing is carried out on the substrate. Finally, Micro LEDs are transferred and baked in a reflow oven to complete soldering. It effectively solves the problems of solder and printed solder in the die bonding process.

[0027] The present invention precisely sprays on the surface of the PCB at the interval between adjacent LED units, so that the glue penetrates into the bottom of the chip and the gap between chip units to fix the LED chips and solve the problem of light crosstalk in the display unit module.

[0028] The present invention adopts a surface super-black nano-coating technology to eliminate color difference, anti-glare, and low reflection on the surface of the RGB module display, achieving a vivid color and rich detail display effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] Figure 1 is a flowchart for preparing a Micro&Mini micro-pitch (less than P0.5) LED display module of the present invention;

[0031] Figure 2 is a flowchart for preparing a lamp board of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Please refer to Figure 1-2 As shown, the present invention is a method for manufacturing a Micro&Mini micro-pitch LED display module, including the following steps:

[0034] Step 1: Prepare a Micro&Mini micro-pitch (less than P0.5) LED display module:

[0035] The specific process is as follows:

[0036] Step 1, Cutting: To optimize the operation process and improve the operation efficiency, first, use a dicing saw to evenly divide the MEP substrate with a size of 240mm * 75mm and cut it into 120mm * 75mm;

[0037] Step 2, Cleaning: Use ultrapure water greater than 10MΩ and mix it with industrial alcohol in a ratio of 10:1 to clean the cut MEP substrate (120mm * 75mm) to remove surface dirt;

[0038] Step 3, Dehumidification: Use a blast oven to dry the cleaned MEP substrate;

[0039] Step 4, Correction: Use a leveling tooling to level the cleaned MEP substrate to meet the warpage < 0.5%;

[0040] Step 5, MARK treatment: Use 600-mesh sandpaper to clean the dirt and oxides on the surface of the MARK points of the MEP substrate to facilitate the recognition of the equipment camera;

[0041] Step 6, Ball placement: Make a screen, according to the pad positions and shapes on the MEP substrate, make a screen for stencil printing solder paste, and evenly coat the solder on each pad under the action of a squeegee, then put it into a reflow oven for baking to complete ball placement;

[0042] Step 7, FLUX cleaning: Use a semi-aqueous cleaning solvent to clean the residual flux on the MEP substrate;

[0043] Step 8, Baking: Use a blast oven to dry the cleaned MEP substrate;

[0044] Step 9, Printing: Make a screen, according to the positions and shapes of the solder balls on the MEP substrate, make screen holes for stencil printing flux, and evenly coat the flux on each pad under the action of a squeegee;

[0045] Step 10, SPI: Used to check the uniformity of the flux coating on the MEP substrate (including area, volume, height, offset, bridging, etc.);

[0046] Step 11, Die bonding: Use the One Pixel Structure prepared by Micro Pixel LED to transfer it to the substrate in the most stable 1by1 manner, then put it into a reflow oven for baking to complete welding and make a semi-finished product MEP;

[0047] Step 12. Lighting inspection: Check that the semi-finished MEP has no defects such as missing lighting, dim lighting, or over-brightness.

[0048] Step 13. FLUX cleaning: Use a semi-aqueous cleaning solvent to clean the residual flux on the semi-finished MEP.

[0049] Step 14. Desulfurization cleaning: Use industrial alcohol solution to remove the residual s element on the semi-finished MEP.

[0050] Step 15. Dehumidification: Dry the semi-finished MEP through a blast oven.

[0051] Step 16. Lighting inspection: Check whether the semi-finished MEP has defects such as missing lighting, dim lighting, or over-brightness.

[0052] Step 17. Inkjet printing: Perform precise inkjet printing on the surface of the adjacent LED unit interval PCB, so that the glue penetrates into the bottom of the chip and the gap between the chip units.

[0053] Step 18. Molding: Add a certain amount of epoxy resin glue into the metal die, and then heat and press to cure and form a protective film (or colloid) on the surface of the semi-finished MEP.

[0054] Step 19. Baking: Through a blast oven, perform long baking on the surface of the semi-finished MEP to form a protective film for further curing.

[0055] Step 20. Lighting inspection: Check that the semi-finished MEP after molding has no defects such as missing lighting, dim lighting, or over-brightness.

[0056] Step 21. Cutting: Use a dicing saw to evenly divide the molded semi-finished MEP with a size of 120mm * 75mm into RGB modules of 15mm * 15mm.

[0057] Step 22. Dehumidification: Dry the RGB module through a blast oven.

[0058] Step 23. After quality control confirmation, perform vacuum packaging and storage.

[0059] Step two. Prepare the LED display module; including the production of the BOTTOM substrate and the TOP substrate.

[0060] The specific process of making the BOTTOM substrate is as follows:

[0061] Step 1. BOT-printing: Make a screen, and according to the pad positions and shapes on the lamp board, make a screen for stencil printing solder paste, and evenly coat the solder on each pad under the action of a squeegee.

[0062] Step 2, BOT-SPI: Used to check the uniformity of solder paste coating on the BOT side of the lamp board (including area, volume, height, offset, bridging, etc.);

[0063] Step 3, BOT-Patch: Place ICs, resistors, capacitors, etc. onto the corresponding positions on the BOT side of the lamp board through a mounter, and then put them into a reflow oven for baking to complete soldering;

[0064] Step 4, BOT-AOI (before furnace): Confirm whether there are defects such as missing components, offset, reverse, rotation, foreign objects, etc. before passing through the furnace;

[0065] Step 5, BOT-AOI (after furnace): Confirm whether there are defects such as missing components, offset, reverse, rotation, foreign objects, etc. after passing through the furnace;

[0066] Step 6, BOT-Cutting: Cut the process edge of the semi-finished lamp board through a dicing machine;

[0067] Step 7, BOT-Dehumidification: Dry the semi-finished lamp board through a blast oven;

[0068] Step 8, After quality control confirmation, perform vacuum packaging and warehousing;

[0069] The specific process of TOP substrate production is as follows:

[0070] Step 1, TOP-Printing: Make a silk screen. According to the pad positions and shapes on the semi-finished lamp board, make a silk screen for stenciling solder paste, and evenly coat the solder on each pad under the action of a squeegee;

[0071] Step 2, TOP-SPI: Used to check the uniformity of flux coating on the MEP substrate (including area, volume, height, offset, bridging, etc.);

[0072] Step 3, TOP-Patch: Place the RGB module onto the corresponding position on the TOP side of the lamp board through a mounter. The lamp board is placed in advance in the fixture for RGB module splicing, and then put into a reflow oven for baking to complete soldering

[0073] Step 4, TOP-AOI (before furnace): Confirm whether there are defects such as missing components, offset, reverse, rotation, foreign objects, etc. before passing through the furnace;

[0074] Step 5, TOP-AOI (after furnace): Confirm whether there are defects such as missing components, offset, reverse, rotation, foreign objects, etc. after passing through the furnace;

[0075] Step 6, Surface treatment: Apply a super black nano-coating on the surface through a coating machine;

[0076] Step 7, After quality control confirmation, perform vacuum packaging and warehousing.

[0077] Working principle of the present invention: The present invention is composed of a Top-mounted light-emitting chip, light-emitting chip protection treatment, substrate patch, and packaging, which consists of upper and lower substrate layers interconnected by alloy balls. The driving IC die flipchip method is used to the lower surface of the upper substrate. The upper surface of the upper substrate is a flat plate for soldering LEDs, and the lower surface of the lower substrate is a flat plate for driving IC signals and power supplies. All flat plates are LGA flat plates. The internal driving IC is protected by potting. The entire package can perform two soldering operations;

[0078] A method for manufacturing and splicing a Micro&Mini micro-pitch (less than P0.5) LED display module of the present invention solves the problems of insufficient Layout space for ultra-small pitch (below P0.5), high production difficulty of multi-layer high-density substrates, and explores the physical resolution limit of PCB-based LED displays, making technical reserves for LED display products to enter the ultra-high definition 4K / 8K resolution, and accelerating the trend of laying out the civilian market of micro-pitch LED displays.

[0079] The above has described in detail one embodiment of the present invention, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application should still fall within the scope covered by the patent of the present invention.

Claims

1. Manufacturing method of Micro&Mini micro-pitch LED display module, characterized in that, It includes the following steps: Step 1: Prepare the Micro&Mini micro-pitch LED display module: First, perform batch pre-ball planting on the substrate; then perform batch flux printing on the substrate, and finally transfer the MicroLEDs, place them in a reflow oven for baking, and complete the soldering; Use the adjacent LED unit's spaced PCB surface for inkjet printing to fix the LED chips, and then obtain the RGB module through cutting; Among them, ball planting: Make a silk screen. According to the pad positions and shapes on the MEP substrate, make a silk screen for stenciling solder paste. Under the action of a squeegee, evenly coat the solder on each pad, place it in a reflow oven for baking, and complete the ball planting; Printing: Make a silk screen. According to the positions and shapes of the solder balls on the MEP substrate, make the silk screen holes for stenciling flux. Under the action of a squeegee, evenly coat the flux on each pad; Step 2: Prepare the LED display module; including the production of the BOTTOM substrate and the TOP substrate; In Step 1, before ball planting, complete the processes of MEP substrate cutting, cleaning, dehumidification, calibration, and mark processing; Cutting: Use a dicing machine to evenly divide the MEP substrate with a size of 240mm*75mm and cut it into 120mm*75mm; Calibration: Use a leveling tooling to level the cleaned MEP substrate, with a warpage degree <0.5%; 2. The manufacturing method of the Micro&Mini micro-pitch LED display module according to claim 1, wherein The specific process of making the BOTTOM substrate is as follows: According to the pad positions and shapes on the lamp board, make a silk screen for stenciling solder paste; Put the ICs and resistive-capacitive components into the corresponding positions on the BOT surface of the lamp board through a pick-and-place machine, and then put them into a reflow oven for baking to complete the soldering.

3. The manufacturing method of the Micro&Mini micro-pitch LED display module according to claim 1, characterized in that The specific process of making the TOP substrate is as follows: According to the pad positions and shapes on the semi-finished lamp board, make a silk screen for stenciling solder paste; Put the RGB module into the corresponding position on the TOP surface of the lamp board through a pick-and-place machine. The lamp board is pre-placed in the tooling for splicing the RGB modules, put it into a reflow oven for baking, and complete the soldering; Perform a surface super-black nano-coating through a coating machine.

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