Processing method of display module

Abstract

The application provides a processing method of a display module, comprising the following steps: providing a circuit substrate, the front surface of the circuit substrate being provided with pads; providing an ink layer on the region of the front surface of the circuit substrate except the pad region; respectively welding LED chips on the pads; attaching a transparent protective film on the front surface of the LED chip, the transparent protective film having fluidity at a first temperature, the transparent protective film comprising a first region in contact with the front surface of the LED chip and a second region except the first region; heating the first region to a first temperature, the transparent protective film in the first region flowing and covering the front surface and the side surface of the LED chip, and the second region sinking to the ink layer; and heating the transparent protective film to a second temperature to solidify. The thickness of the transparent protective film on the front surface and the side surface of the LED chip is uniform, the thickness of the transparent protective film on the ink layer is uniform, and the light emission consistency of the LED chip is good.

Description

Technical Field

[0001] This invention relates to the field of display modules, and more particularly to a method for processing display modules. Background Technology

[0002] LED direct display screen is a flat panel display technology that uses light-emitting diodes (LEDs) as pixel units to display images. With its advantages such as high brightness, high contrast, wide color gamut, long life and good environmental adaptability, it has been widely used in commercial advertising, stage performances, security monitoring, command and dispatch centers, sports venues and high-end conferences and exhibitions, becoming the mainstream solution for large-size, high-definition dynamic information presentation.

[0003] LED display modules are manufactured by fixing RGB Mini / Micro LED chips to one surface of a circuit board and controlling the display through a driver IC on the other surface. Chinese patent application number CN202310023051.5 discloses a method for manufacturing a display module, a display module, and a rework method. It involves mounting several LED chips on the front side of a substrate, then forming a thin protective layer through "spraying," and finally attaching a protective film to complete the display module manufacturing. Although the thin protective layer is transparent, its thickness and shape can still vary microscopically, thus affecting the light emission effect after the protective film is attached. Summary of the Invention

[0004] The purpose of this invention is to provide a processing method for display modules, so as to solve the problem that in the prior art, the thickness or shape of the thin film protective layer formed by spraying still varies, which affects the light emission effect after the encapsulation film is applied.

[0005] To achieve the above objectives, the present invention provides a method for processing a display module, comprising the following steps: providing a circuit board, wherein a plurality of pads are provided on the front side of the circuit board; forming an ink layer on the front side of the circuit board excluding the pad area; soldering LED chips onto the plurality of pads to form a plurality of light-emitting units; providing a transparent protective film, attaching the transparent protective film to the front side of the plurality of LED chips, the transparent protective film comprising an adhesive material, the transparent protective film being fluid at a first temperature and curing at a second temperature, the first temperature being lower than the second temperature, the transparent protective film comprising a first area in contact with the front side of the LED chip and a second area excluding the first area; heating the first area to raise its temperature to the first temperature, wherein the transparent protective film in the first area flows and covers the front side and side of the LED chip, and the second area sinks to the ink layer; heating the transparent protective film to raise its temperature to the second temperature to cure the transparent protective film to form a thin film protective layer attached to the ink layer, the front side and side of the LED chip.

[0006] Preferably, the step of heating the first region to the first temperature includes: lighting the LED chip to use the heat from the LED chip emitting light to heat the first region to the first temperature.

[0007] Preferably, the step of heating the first region to the first temperature includes: providing a first mask plate having a window corresponding to the first region; placing the first mask plate above the transparent protective film and irradiating the window with a laser to heat the first region to the first temperature.

[0008] Preferably, the first temperature is greater than or equal to 40°C and less than or equal to 60°C, and the second temperature is greater than or equal to 80°C and less than or equal to 150°C.

[0009] Preferably, the step of providing a transparent protective film includes: providing a transparent protective film with a first thickness, wherein the first thickness is greater than or equal to 15 micrometers and less than or equal to 40 micrometers.

[0010] Preferably, the thickness of the thin film protective layer located on the front and side surfaces of the LED chip is a second thickness, which is greater than or equal to 5 micrometers and less than or equal to 20 micrometers, and the thickness of the thin film protective layer located on the ink layer is a third thickness, which is greater than or equal to 15 micrometers and less than or equal to 45 micrometers.

[0011] Preferably, the LED chip is rectangular, and the transparent protective film has multiple through holes in its thickness direction. The diameter of the through holes is smaller than the width of the LED chip. The step of attaching the transparent protective film to the front surface of the multiple LED chips includes: attaching the transparent protective film to the front surface of the multiple LED chips using a roll forming process; and using a vacuum process to extract air from the through holes to press the transparent protective film onto the front surface of the LED chip and remove air bubbles between the transparent protective film and the LED chip.

[0012] Preferably, the step of forming an ink layer on the front side of the circuit board, excluding the pad area, includes: providing a photosensitive solder resist ink film, the photosensitive solder resist ink film being formed by a coating process; attaching the photosensitive solder resist ink film to the front side of the circuit board, the photosensitive solder resist ink film forming a first photosensitive area corresponding to the pad area and a second photosensitive area other than the first photosensitive area; processing the photosensitive solder resist ink film using an exposure and development process to remove the first photosensitive area to expose the pad; and curing the second photosensitive area to form an ink layer on the front side of the circuit board, excluding the pad area.

[0013] Preferably, the photosensitive solder resist film is formed from photosensitive solder resist ink, the components of which include negative photosensitive resin, epoxy resin, photoinitiator, diluent, and carbon black pigment. The step of treating the photosensitive solder resist film with an exposure and development process to remove the first photosensitive area and expose the solder pad includes: treating the second photosensitive area with an exposure process to pre-cure the second photosensitive area; and treating the photosensitive solder resist film with a development process to remove the first photosensitive area.

[0014] Preferably, after heating the transparent protective film to the second temperature to cure the transparent protective film to form a thin film protective layer attached to the ink layer, the front side, and the side side of the LED chip, the method further includes: providing an encapsulation film, the bottom layer of which is a soft adhesive layer; attaching the encapsulation film to the front side of the circuit board through the soft adhesive layer, and filling the gaps between adjacent LED chips with the soft adhesive layer; and curing the encapsulation film to encapsulate the LED chip.

[0015] Compared with the prior art, the present invention attaches a transparent protective film to the front of the LED chip and heats only the first area to further attach the transparent protective film in the first area to the side of the LED chip. This makes the thickness of the transparent protective film on the front and side of the LED chip uniform, and the thickness of the transparent protective film on the ink layer uniform, thereby ensuring good flatness after the encapsulation film is attached and effectively ensuring good light output consistency of the LED chip. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the circuit board structure in an embodiment of the present invention.

[0017] Figure 2 This is a structural diagram of the circuit board after a photosensitive solder resist film has been attached to it, according to an embodiment of the present invention.

[0018] Figure 3 This is a structural diagram of the photosensitive solder resist ink film after being processed by exposure and development process and then cured to form an ink layer in an embodiment of the present invention.

[0019] Figure 4 This is a structural diagram of the LED chip after it has been soldered onto the pads in an embodiment of the present invention.

[0020] Figure 5 This is a structural diagram of the second carrier layer, the transparent protective film, and the second protective film in an embodiment of the present invention.

[0021] Figure 6 This is a structural diagram of the LED chip after a transparent protective film has been attached to the front side in an embodiment of the present invention.

[0022] Figure 7 This is a structural diagram of the transparent protective film after it has been heated and cured to form a thin film protective layer in an embodiment of the present invention.

[0023] Figure 8 This is a structural diagram of a display module formed by attaching an encapsulation film to a transparent protective layer in an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached diagram: 1. Circuit board; 11. Pad; 111. Positive electrode pad; 112. Negative electrode pad; 2. Photosensitive solder resist film; 21. First photosensitive area; 22. Second photosensitive area; 3. Ink layer; 4. Second carrier layer; 5. LED chip; 51. Positive electrode; 52. Negative electrode; 61. First carrier layer; 62. Transparent protective film; 621. First area; 622. Second area; 63. First protective film; 7. Thin film protective layer; 71. First thin film section; 72. Second thin film section; 8. Encapsulation film; 10. Display module. Detailed Implementation

[0025] To illustrate the technical content, structural features, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0026] like Figures 1 to 8 As shown, this embodiment of the invention provides a method for processing a display module, including the following steps: S1. A circuit board 1 is provided, and a plurality of pads 11 are provided on the front side of the circuit board 1; specifically, such as Figure 1 As shown, the circuit board 1 can be a PCB board, glass board, BT board, or other circuit board. The pads 11 are used to solder the LED chips 5, and the pads 11 can be arranged in an array. It should be noted that the pads 11 here can be a single positive pad 111 and a single negative pad 112 for contacting the positive electrode 51 and negative electrode 52 of a single LED chip 5, or it can be a group of pads consisting of three positive pads 111 and three corresponding negative pads 112 for contacting the positive electrodes 51 and negative electrodes 52 of red, green, and blue LED chips respectively. Specifically, as shown... Figure 1 The pad 11 is shown in the dashed box. In addition, there are a large number of pads 11, for example, there can be thousands or even tens of thousands of pads 11, and the gap between adjacent pads 11 is very small, reaching the millimeter level.

[0027] S2. An ink layer 3 is applied to the front side of the circuit board 1, excluding the pad area; specifically, as shown in the example... Figure 3 As shown, by setting the ink layer 3, the ink color of the display module 10 is effectively guaranteed to be consistent when it is not lit.

[0028] S3. Solder LED chips 5 onto several pads 11 to form multiple light-emitting units; specifically, as shown in the figure. Figures 5 to 4 As shown, there are multiple LED chips 5, usually arranged in an array. The LED chips 5 are Mini LED chips or Micro LED chips. The positive electrode 51 and negative electrode 52 of each LED chip 5 are respectively soldered to a corresponding positive electrode pad 111 and a negative electrode pad 112. Each light-emitting unit may include only one LED chip 5, or it may be an LED package containing three colors of light: red LED chip, green LED chip and blue LED chip.

[0029] S4. A transparent protective film 62 is provided and attached to the front side of multiple LED chips 5. The transparent protective film 62 includes an adhesive material. The transparent protective film 62 is fluid at a first temperature and cures at a second temperature, where the first temperature is lower than the second temperature. The transparent protective film 62 includes a first region 621 in contact with the front side of the LED chips 5 and a second region 622 excluding the first region 621. Specifically, as shown... Figure 6As shown, the transparent protective film 62 includes an adhesive material, which is one or more of epoxy resin, silicone resin, acrylic resin, and polyurethane. The transparent protective film 62 may also include a diffusing powder, which is silica. The diffusing powder helps to transform the dot-shaped light spot of the LED chip 5 into a planar light spot. When the transparent protective film 62 is heated to a first temperature, its viscosity decreases significantly and its fluidity increases; when heated to a second temperature, its fluidity decreases and the colloid permanently cures. The first temperature can be greater than or equal to 40°C and less than or equal to 60°C, and the second temperature can be greater than or equal to 80°C and less than or equal to 150°C. The application of the transparent protective film 62 can be performed in a cleanroom with a cleanliness level of Class 1000 or higher. The application temperature of the transparent protective film 62 can be greater than or equal to 20°C and less than or equal to 25°C, and the application humidity of the transparent protective film 62 can be greater than or equal to 50% RH and less than or equal to 60% RH.

[0030] S5. The first region 621 is heated to a first temperature. The transparent protective film 62 in the first region 621 flows and covers the front and sides of the LED chip 5, while the second region 622 sinks onto the ink layer 3; specifically, as shown... Figures 6 to 7 In this step, only the first region 621 is heated, while the second region 622 is not heated. This differentiated heating softens and allows the transparent protective film 62 in the first region 621 to flow and further adhere to the side of the LED chip 5. This reduces the thickness of the transparent protective film 62 on the front of the LED chip 5, while the transparent protective film 62 in the second region 622 is less affected by heat and naturally sinks to the ink layer 3. The heating time and specific first temperature in this step can be set according to actual needs, as long as the front and side of the LED chip 5 have transparent protective films 62. This embodiment of the invention heats only the first region 621, allowing the transparent protective film 62 in the first region 621 to further adhere to the side of the LED chip 5. This results in uniform thickness of the transparent protective film 62 on the front and side of the LED chip 5, and uniform thickness of the transparent protective film 62 on the ink layer 3. This ensures good flatness of the encapsulation film 8 after application in subsequent steps S7 and S8, and good light emission consistency of the LED chip.

[0031] S6. The transparent protective film 62 is heated to a second temperature to cure it, forming a thin film protective layer 7 attached to the ink layer 3, the front and sides of the LED chip 5. Specifically, the thin film protective layer 7 can effectively protect the LED chip 5 and prevent damage to the normal LED chip 5 when the outermost encapsulation film 8 is removed during subsequent repairs of individual damaged LED chips 5.

[0032] In this embodiment of the invention, a transparent protective film 62 is attached to the front side of the LED chip 5, and only the first region 621 is heated so that the transparent protective film 62 in the first region 621 is further attached to the side of the LED chip 5. This makes the thickness of the transparent protective film 62 on the front and side of the LED chip 5 uniform, and the thickness of the transparent protective film 62 on the ink layer 3 uniform. This ensures good flatness of the encapsulation film 8 after it is attached, and effectively ensures good light emission consistency of the LED chip 5.

[0033] In this embodiment of the invention, step S5, which involves heating the first region 621 to a first temperature, includes: S51. Light up the LED chip 5 to heat the first region 621 to a first temperature using the heat generated when the LED chip 5 emits light. Specifically, lighting up the LED chip 5 can also detect whether the LED chip 5 soldered in step S3 can be continuously lit or work normally.

[0034] In some other specific embodiments of the present invention, step S5, which involves heating the first region 621 to a first temperature, includes: S501. A first mask is provided, the first mask having a window set corresponding to the first region 621.

[0035] S502. Place the first mask plate above the transparent protective film 62, and use a laser to irradiate the window to heat the first region 621 to a first temperature. Specifically, the window position is directly opposite the position of the first region 621 so that the laser passes through the window to irradiate the first region 621 to heat the first region 621.

[0036] In this embodiment of the invention, step S4, providing the transparent protective film 62, includes: S41. A transparent protective film 62 with a first thickness is provided, the first thickness being greater than or equal to 15 micrometers and less than or equal to 40 micrometers. Specifically, the first thickness is less than the height of the LED chip 5, the height of the LED chip 5 being typically greater than or equal to 80 micrometers and less than or equal to 150 micrometers.

[0037] In this embodiment of the invention, the thickness of the thin film protective layer 7 located on the front and side surfaces of the LED chip 5 is a second thickness, which is greater than or equal to 5 micrometers and less than or equal to 20 micrometers. The thickness of the thin film protective layer 7 located on the ink layer 3 is a third thickness, which is greater than or equal to 15 micrometers and less than or equal to 45 micrometers. Specifically, as shown... Figure 7As shown, the thin film protective layer 7 located on the front and side of the LED chip 5 is the first thin film portion 71, and the thin film protective layer 7 located on the ink layer 3 is the second thin film portion 72. The thickness of the second thin film portion 72 can remain basically unchanged.

[0038] In this embodiment of the invention, the LED chip 5 is rectangular, and the transparent protective film 62 has multiple through holes in its thickness direction. The diameter of the through holes is smaller than the width of the LED chip 5. Step S4, which involves attaching the transparent protective film 62 to the front surface of the multiple LED chips 5, includes: S42. A transparent protective film 62 is attached to the front side of multiple LED chips 5 using a roll forming process. Specifically, the transparent protective film 62 is formed through a coating process, ensuring that the thickness error of the transparent protective film 62 can be controlled within ±1 micrometer, resulting in a very uniform thickness and thus guaranteeing the consistency of light output from the LED chips 5. The coating process can be one of the following: slot coating, double-roller extrusion coating, micro-recessed coating, or comma blade coating. Figure 5 As shown, a transparent protective film 62 is typically disposed on a first carrier layer 61. The first carrier layer 61 is a heavy release film, and the material of the first carrier layer 61 is PET, PC, or TPU. The thickness of the first carrier layer 61 is greater than or equal to 50 μm and less than or equal to 200 μm. The release force between the first carrier layer 61 and the transparent protective film 62 is greater than or equal to 45 g / inch and less than or equal to 100 g / inch. A first protective film 63 is also disposed on the transparent protective film 62. The first protective film 63 is a light release film, and the material of the first protective film 63 is PE. The thickness of the first protective film 63 is greater than or equal to 25 μm and less than or equal to 50 μm. The release force between the first protective film 63 and the transparent protective film 62 is greater than or equal to 5 g / inch and less than or equal to 15 g / inch. When the transparent protective film 62 is needed, simply peel off the first protective film 63 to expose the transparent protective film 62. Then, attach the transparent protective film 62 to the front of the LED chip 5 and lightly press it together using a rolling process. The rolling pressure is greater than or equal to 1 MPa and less than or equal to 2.5 MPa. After rolling, the bonding force between the transparent protective film 62 and the LED chip 5 is greater than the release force between the first carrier layer 61 and the transparent protective film 62. Therefore, the first carrier layer 61 can be peeled off without affecting the transparent protective film 62.

[0039] S43. A vacuum process is used to evacuate air from the through-hole to press the transparent protective film 62 onto the front side of the LED chip 5 and remove air bubbles between the transparent protective film 62 and the LED chip 5. Specifically, the size of the through-hole is greater than or equal to 50 nanometers and less than or equal to 5 micrometers. The size of the through-hole is much smaller than the length and width of the LED chip 5. The through-hole can be set only in the first region 621. The setting of the through-hole facilitates the evacuation of vacuum between the transparent protective film 62 and the front side of the LED chip 5.

[0040] In this embodiment of the invention, step S2, which involves setting an ink layer 3 on the front side of the circuit board 1, excluding the area of ​​the solder pads 11, includes: S21. Provide a photosensitive solder resist ink film 2, which is formed by a coating process; specifically, such as... Figures 2 to 3 As shown, the thickness error of the photosensitive solder resist ink film 2 formed by the coating process can be controlled within ±1 micrometer. The thickness of the photosensitive solder resist ink film 2 is very uniform, ensuring the consistency of ink color. The coating process can be one of the following: slit coating, double-roller extrusion coating, micro-recessed coating, or comma blade coating.

[0041] S22. The photosensitive solder resist film 2 is attached to the front side of the circuit board 1. The photosensitive solder resist film 2 forms a first photosensitive area 21 corresponding to the area of ​​the solder pad 11 and a second photosensitive area 22 other than the first photosensitive area 21. Specifically, when not in use, the photosensitive solder resist film 2 is usually disposed on the second carrier layer 4. The second carrier layer 4 is a release film. The material of the second carrier layer 4 is PET, PC or TPU. The thickness of the second carrier layer 4 is greater than or equal to 50um and less than or equal to 200um. The release force between the second carrier layer 4 and the photosensitive solder resist film 2 is greater than or equal to 45 g / inch and less than or equal to 100 g / inch. A second protective film is also covered on the photosensitive solder resist film 2. The second protective film is a lightweight release film made of PE material, with a thickness greater than or equal to 25 μm and less than or equal to 50 μm. The release force between the second protective film and the transparent protective film 62 is greater than or equal to 5 g / inch and less than or equal to 15 g / inch. When the photosensitive solder resist film 2 needs to be used, simply peel off the second protective film to expose the photosensitive solder resist film 2, and then attach the photosensitive solder resist film 2 to the front side of the circuit board 1. Figure 3As shown, a rolling process is used for bonding, with a rolling pressure greater than or equal to 3 MPa and less than or equal to 5 MPa. Alternatively, a vacuum process can be used to bond the photosensitive solder resist ink film 2 onto the circuit board 1, removing air bubbles between the photosensitive solder resist ink film 2 and the circuit board 1. The vacuum level of the vacuum process can be greater than or equal to -0.98 MPa and less than or equal to -0.85 MPa, ensuring more reliable adhesion between the photosensitive solder resist ink film 2 and the circuit board 1. The thickness of the photosensitive solder resist ink film 2 is greater than or equal to 15 micrometers and less than or equal to 25 micrometers, ensuring that the thickness of the cured ink layer 3 in step S24 is greater than the thickness of the solder pad 11, and the difference in thickness between the two is less than 3 micrometers. The application of the photosensitive solder resist film 2 can be carried out in a cleanroom with a cleanliness level of Class 1000 or higher. The application temperature of the photosensitive solder resist film 2 can be greater than or equal to 20°C and less than or equal to 25°C. The application humidity of the photosensitive solder resist film 2 can be greater than or equal to 50% RH and less than or equal to 60% RH.

[0042] S23. The photosensitive solder resist film 2 is processed using an exposure and development process to remove the first photosensitive area 21 to expose the solder pad 11. Specifically, as follows... Figures 2 to 3 As shown, the first photosensitive area 21 is removed by the exposure and development process, thereby exposing the pad 11, while the second photosensitive area 22 is retained as a barrier between adjacent pads 11.

[0043] S24. The second photosensitive area 22 is cured to form an ink layer 3 on the front side of the circuit board 1, excluding the area of ​​the solder pad 11. Specifically, the circuit board 1 and the second photosensitive area 22 retained on the circuit board 1 can be baked at a first temperature for a first time. The first temperature is greater than or equal to 140 degrees Celsius and less than or equal to 160 degrees Celsius, preferably 150 degrees Celsius, and the first time can be greater than or equal to 1 hour and less than or equal to 4 hours. After high-temperature baking and curing, the second photosensitive area 22 of the photosensitive solder resist ink film 2 is firmly attached to the surface of the circuit board 1. It has extremely low fluidity and is not easily changed by environmental conditions such as light and high temperature. It is also not easily worn during the subsequent processing of the display module 10, and the ink color of the circuit board 1 is highly consistent.

[0044] In this embodiment of the invention, the photosensitive solder resist film 2 is formed from photosensitive solder resist ink. The components of the photosensitive solder resist ink include negative photosensitive resin, epoxy resin, photoinitiator, diluent, and carbon black pigment. In step S23, the photosensitive solder resist film 2 is treated with an exposure and development process to remove the first photosensitive area 21 to expose the solder pad 11. The step includes: S231. The second photosensitive area 22 is treated using an exposure process to preliminarily cure the second photosensitive area 22; specifically, the first photosensitive area 21 of the photosensitive solder resist film 2 is shielded using a second mask, and the second photosensitive area 22 is irradiated with a UV lamp with a wavelength of 365 nm or 395 nm, wherein the energy density of the UV lamp is greater than or equal to 3500 mJ / cm². 2 Alternatively, a mercury lamp can be used to irradiate the second photosensitive area 22, causing it to undergo a cross-linking reaction. After the cross-linking reaction, the second photosensitive area 22 becomes insoluble in the developing solution used in step S232. Furthermore, the second carrier layer 4 can be removed after the exposure process to allow the photosensitive solder resist film 2 to undergo subsequent developing processes. The bonding force between the second photosensitive area 22 and the circuit board 1 is greater than the release force between the second carrier layer 4 and the second photosensitive area 22, thus allowing the second carrier layer 4 to be removed without affecting the second photosensitive area 22.

[0045] S232. The photosensitive solder resist film 2 is processed by a developing process to remove the first photosensitive area 21. Specifically, the circuit board 1 and the photosensitive solder resist film 2 are placed in a developing solution. The photosensitive solder resist ink in the second photosensitive area 22 after exposure is insoluble in the developing solution, while the photosensitive solder resist ink in the first photosensitive area 21 is soluble in the developing solution, thereby removing the first photosensitive area 21 and retaining only the second photosensitive area 22.

[0046] It should be noted that when the components of photosensitive solder resist ink include negative photosensitive resin, epoxy resin, photoinitiator, diluent, and carbon black pigment, the photosensitive solder resist ink is a photolithographic negative resist with added carbon black pigment. The negative photosensitive resin can be one or more of cyclized polyisoprene, bisphenol A type epoxy resin, polymethyl methacrylate (PMMA), or modified acrylate. The photoinitiator can be a diazid compound, benzophenone, or benzoin ether. The diluent can be xylene, propylene glycol methyl ether acetate, or ethylene glycol monoethyl ether. The first developer generally uses organic solvents such as xylene or propylene glycol methyl ether acetate (PGMEA). Of course, the photolithographic negative resist and the corresponding developer are conventional photolithography process materials, and the specific materials can be selected according to actual needs, which will not be elaborated here.

[0047] Of course, in some other specific embodiments, the components of the photosensitive solder resist ink may also include positive photosensitive resin, epoxy resin, photoacid generator, diluent, and carbon black pigment. That is, the photosensitive solder resist ink is a photoresist with added carbon black pigment. The positive photosensitive resin can be linear phenolic resin, acrylate, or fluorinated resin. The photoacid generator can be triphenylsulfonate or sulfonate. The diluent can be propylene glycol methyl ether acetate, ethyl lactate, or cyclohexanone. Correspondingly, the developer is generally an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH). In this case, a third mask can be used to shield the second photosensitive area 22 of the photosensitive solder resist ink film 2. The first photosensitive area 21 can be irradiated with a UV lamp with a wavelength of 365 nm or 395 nm. Alternatively, a mercury lamp can be used to irradiate the first photosensitive area 21, so that the first photosensitive area 21 can be dissolved in the corresponding developer to remove the first photosensitive area 21, leaving only the second photosensitive area 22. Of course, photoresist and the corresponding developer are conventional photoresist materials. The specific materials can be selected according to actual needs, and will not be elaborated here.

[0048] In this embodiment of the invention, after heating the transparent protective film 62 to a second temperature to cure the transparent protective film 62 to form a thin film protective layer 7 attached to the ink layer 3, the front side, and the side side of the LED chip 5, step S6 further includes: S7. A packaging film 8 is provided. The bottom layer of the packaging film 8 is a soft adhesive layer. The packaging film 8 is attached to the front side of the circuit board 1 through the soft adhesive layer, and the soft adhesive layer fills the gap between adjacent LED chips 5. Specifically, in this embodiment, the soft adhesive layer is an OCA soft adhesive layer. The soft adhesive layer can be formed by a coating process. Of course, other elastic adhesive materials can also be selected as the soft adhesive layer, not limited to OCA soft adhesive. The packaging film 8 also includes a PET transparent layer formed on the soft adhesive layer and a black ink layer 3 formed on the PET transparent layer. The packaging film 8 also includes a functional layer formed on the black ink layer 3. The functional layer is an AG layer, an AR layer, or an AF layer, etc. Among them, the AR (Anti-Reflection) layer is an anti-reflection film layer or glass, the AG (Anti-Glare) layer is an anti-glare film layer or glass, and the AF (Anti-Fingerprint) layer is an anti-fingerprint film layer or glass. The soft adhesive layer contains a diffusion powder material, which helps to convert the dot-shaped light spot of the LED chip 5 into a surface light spot. The diffuser powder is made of silicon dioxide, and the thickness of the soft adhesive layer is greater than or equal to 100 micrometers, specifically 150 micrometers. This thickness can be appropriately increased or decreased depending on the size of the LED chip 5. Since the encapsulation film 8 has functional layers, no additional carrier layer is required. A third protective film, a light release film made of PE, is also covered on the encapsulation film 8. The thickness of the third protective film is greater than or equal to 25 μm and less than or equal to 50 μm, and the release force between the third protective film and the transparent protective film 62 is greater than or equal to 5 g / inch and less than or equal to 15 g / inch. When the encapsulation film 8 is required, simply peel off the third protective film to expose the encapsulation film 8. Then, attach the encapsulation film 8 to the front side of the circuit board 1 and press it using a roll forming process. The roll forming pressure is greater than or equal to 3 MPa and less than or equal to 5 MPa. Alternatively, a vacuum process can be used to press the encapsulation film 8 onto the thin film protective layer 7, removing air bubbles between the encapsulation film 8 and the thin film protective layer 7. The vacuum degree of the vacuum process can be greater than or equal to -0.98 MPa and less than or equal to -0.85 MPa to ensure more reliable adhesion between the encapsulation film 8 and the thin film protective layer 7. The attachment of the encapsulation film 8 can be performed in a cleanroom with a cleanliness level of Class 1000 or higher. The attachment temperature of the encapsulation film 8 can be greater than or equal to 20°C and less than or equal to 25°C, and the attachment humidity can be greater than or equal to 50% RH and less than or equal to 60% RH.

[0049] It should be noted that in some other specific embodiments, the encapsulation film 8 includes a carbon black layer formed on the soft adhesive layer and a PET transparent layer formed on the carbon black layer. Of course, other ink materials can be used to make the ink to replace the carbon black layer, and it is not limited to carbon black. Similarly, other transparent insulating materials can be used to make the transparent layer to replace the PET transparent layer, and it is not limited to PET. The encapsulation film 8 also includes a functional layer formed on the PET transparent layer. The functional layer can be an AG layer, an AR layer, or an AF layer, etc.

[0050] S8. The encapsulation film 8 is used to encapsulate the LED chip 5. The soft adhesive layer is baked at 70-80°C for 3-5 minutes, followed by UV curing. This curing process improves the adhesion between the soft adhesive layer and the protective film 7. It should be noted that the adhesion between the protective film 7 and the LED chip 5, as well as the ink layer 3, is greater than the adhesion between the protective film 7 and the soft adhesive layer. Therefore, when the display module 10 needs rework and the encapsulation film 8 is removed, the contact surface between the soft adhesive layer and the protective film 7 becomes a separation interface, while the protective film 7 remains adhered to the surfaces of the LED chip 5 and the circuit board 1, thus protecting the normally functioning LED chip 5.

[0051] In this embodiment of the invention, a photosensitive solder resist ink film 2, a transparent protective film 62, and an encapsulation film 8 are formed through a coating process. This ensures good thickness consistency among the photosensitive solder resist ink film 2, the transparent protective film 62, and the encapsulation film 8, thereby guaranteeing good ink color consistency in the manufactured display module 10 and good light emission performance of the LED chip 5. Furthermore, the photosensitive solder resist ink film 2, the transparent protective film 62, and the encapsulation film 8 of this invention all employ a lamination process, effectively saving processing time and improving production efficiency.

[0052] The above-disclosed examples are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for processing a display module, characterized in that, Includes the following steps: A circuit board is provided, wherein a plurality of pads are provided on the front side of the circuit board; An ink layer is formed on the front side of the circuit board, excluding the pad area. LED chips are soldered onto several of the aforementioned pads to form multiple light-emitting units; A transparent protective film is provided and attached to the front side of the LED chip. The transparent protective film includes an adhesive material, is fluid at a first temperature, and is cured at a second temperature, wherein the first temperature is lower than the second temperature. The transparent protective film includes a first area in contact with the front side of the LED chip and a second area other than the first area. The first region is heated to the first temperature, the transparent protective film in the first region flows and covers the front and side of the LED chip, and the second region sinks onto the ink layer; The transparent protective film is heated to the second temperature to cure it and form a thin film protective layer attached to the ink layer, the front side and the side side of the LED chip.

2. The processing method of the display module as described in claim 1, characterized in that, The step of heating the first region to raise its temperature to the first temperature includes: The LED chip is lit up so that the heat generated when the LED chip emits light can be used to heat the first area to raise its temperature to the first temperature.

3. The processing method of the display module as described in claim 1, characterized in that, The step of heating the first region to raise its temperature to the first temperature includes: A first mask is provided, the first mask having a window disposed corresponding to the first region; The first mask is placed above the transparent protective film, and the window is irradiated with a laser to heat the first area to the first temperature.

4. The processing method of the display module as described in claim 1, characterized in that, The first temperature is greater than or equal to 40°C and less than or equal to 60°C, and the second temperature is greater than or equal to 80°C and less than or equal to 150°C.

5. The processing method of the display module as described in claim 1, characterized in that, The steps for providing a transparent protective film include: A transparent protective film with a first thickness is provided, wherein the first thickness is greater than or equal to 15 micrometers and less than or equal to 40 micrometers.

6. The processing method of the display module as described in claim 5, characterized in that, The thickness of the thin film protective layer located on the front and side surfaces of the LED chip is a second thickness, which is greater than or equal to 5 micrometers and less than or equal to 20 micrometers. The thickness of the thin film protective layer located on the ink layer is a third thickness, which is greater than or equal to 15 micrometers and less than or equal to 45 micrometers.

7. The processing method of the display module as described in claim 1, characterized in that, The LED chip is rectangular, and the transparent protective film has multiple through holes in its thickness direction. The diameter of the through holes is smaller than the width of the LED chip. The step of attaching the transparent protective film to the front side of the multiple LED chips includes: The transparent protective film is attached to the front side of multiple LED chips using a roll forming process; A vacuum process is used to extract air from the through-hole to press the transparent protective film onto the front side of the LED chip and remove air bubbles between the transparent protective film and the LED chip.

8. The processing method of the display module as described in claim 1, characterized in that, The step of applying an ink layer on the front side of the circuit board, excluding the pad area, includes: A photosensitive solder resist ink film is provided, the photosensitive solder resist ink film being formed by a coating process; The photosensitive solder resist film is attached to the front side of the circuit board, and the photosensitive solder resist film forms a first photosensitive area corresponding to the solder pad area and a second photosensitive area other than the first photosensitive area. The photosensitive solder resist film is processed using an exposure and development process to remove the first photosensitive area and expose the solder pads; The second photosensitive area is cured to form an ink layer on the front side of the circuit board, excluding the pad area.

9. The processing method of the display module as described in claim 8, characterized in that, The photosensitive solder resist film is formed from photosensitive solder resist ink, the components of which include negative photosensitive resin, epoxy resin, photoinitiator, diluent, and carbon black pigment. The step of processing the photosensitive solder resist film using an exposure and development process to remove the first photosensitive area and expose the solder pads includes: The second photosensitive area is processed using an exposure process to pre-cure the second photosensitive area; The photosensitive solder resist film is processed by a developing process to remove the first photosensitive area.

10. The processing method of the display module as described in claim 1, characterized in that, After heating the transparent protective film to the second temperature to cure it and form a thin film protective layer attached to the ink layer, the front side, and the side side of the LED chip, the method further includes: An encapsulation film is provided, the bottom layer of which is a soft adhesive layer. The encapsulation film is attached to the front side of the circuit board through the soft adhesive layer, and the soft adhesive layer fills the gap between adjacent LED chips. The encapsulation film is cured to encapsulate the LED chip.

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