A multilayer film for MiniLED packaging and a method of using the same

Abstract

The present invention discloses a multilayer film applied to MiniLED packaging. The multilayer film contains at least two layers: a black layer and a translucent layer, and the multilayer film can soften and flow at high temperature. The black layer plays the function of filling the space between MiniLED chips to cover the original color of the substrate, and the translucent layer covers the top of the chip. Precision coating technology is used to first prepare a multilayer adhesive film with uniform thickness and uniform black color, and then a good pressing process is used to assist in solving the problems of black uniformity of the MiniLED display module and side light leakage of the module during assembly. At the same time, the problems of large thickness tolerance caused by the use of liquid resin and the covering of the top of the MiniLED chip by the black liquid resin are solved. One-time pressing and molding improves production efficiency and yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of MiniLED display screen packaging, and specifically relates to a multilayer film applied to MiniLED packaging and a use method thereof. Background Art

[0002] MiniLED display screens have become one of the hot spots in the development of display technology in recent years. Compared with LCD screens, they have the characteristics of high contrast and high brightness. Compared with organic light-emitting semiconductors (OLEDs), they have the characteristics of no screen burn-in, long service life, and seamless splicing. With the development of solid crystal technology for mass transfer in recent years, several leading domestic LED packaging companies have been able to mass-produce MiniLEDs below P1.0, which can be viewed at close range indoors. Usually, MiniLED display screens use a certain number of small MiniLED display modules to seamlessly splice into large-sized MiniLED display screens. Usually, MiniLED display modules fix red, green, and blue MiniLED chips on a substrate. Each substrate cannot guarantee black uniformity due to the influence of different process processes during its production process. In addition, the problem of side light leakage during the assembly of MiniLED display modules also needs to be solved.

[0003] To solve the above problems, patent application number 201911149485.X and patent application number 201911150719.2 use black liquid resin to fill between MiniLEDs. In order to prevent the top of the MiniLED chip from being covered by black resin, the two patent application numbers respectively use the process of pre-protecting the top of the chip and post-etching to remove the lamination layer to leak out the light exit window. There are tens of thousands of MiniLED chips on each MiniLED display module, and some chips will be offset when the chips are fixed. It is difficult to achieve precise pre-protection and post-etching on the top of each chip to leak out the light exit window, and it is difficult to achieve mass production.

[0004] Patent application number 202110394045.7 and patent application number 202110273519.7 use glue spraying and glue dispensing to fill the black liquid resin between the MiniLED chips respectively. There is no mention of whether the top of the MiniLED chip will also be covered with black resin and the corresponding removal process. Patent application number 202110394045.7 mentions that the glue spraying tolerance is ±15μm. Even if the same black liquid resin is used, a large thickness tolerance will also cause inconsistent blackness in human vision. For this reason, we propose a multilayer film and method of use for MiniLED packaging. Summary of the invention

[0005] The object of the present invention is to provide a multilayer film applied to MiniLED packaging and a method of use to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a multi-layer film applied to MiniLED packaging, the multi-layer film contains at least two layers: a black layer and a translucent layer, and the multi-layer film can soften and flow at high temperature, the black layer serves to fill the space between the MiniLED chips to cover the original color of the substrate, and the translucent layer covers the top of the chip.

[0007] Preferably, the black layer is a semi-cured resin composition, and the black layer is pressed between the MiniLED chips and between the positive and negative electrode soldering feet of the chips by hot pressing.

[0008] Preferably, the black layer is a semi-cured resin composition with carbon black added, with a transmittance of 0.1%-30% and a thickness of 1-100μm, and a semi-cured transparent layer is arranged between the black layer and the translucent layer. During the lamination process, the resin of the semi-cured transparent layer can squeeze out the black resin remaining directly above the MiniLED chip. The transmittance of the semi-cured transparent layer is 50%-95%, and the thickness is 10-100μm.

[0009] Preferably, a resin layer is provided under the black layer, the thickness of the resin layer is 1-30 μm, and the sum of the thickness of the resin layer and the black layer is less than the height of the MiniLED chip.

[0010] Preferably, the semi-transparent layer is a resin composition added with carbon black, the transmittance is preferably 30-90%, and the thickness is preferably 10-300 μm.

[0011] Preferably, a hardened hydrophobic layer is provided on the translucent layer, the thickness of the hardened hydrophobic layer is preferably 1-10 μm, and the hardness after curing is 5-7H.

[0012] A method for using a multilayer film applied to MiniLED packaging, wherein the multilayer film is placed on a substrate with a MiniLED chip by hot pressing. After heating and curing, the multilayer film covers the original color of the substrate, giving each substrate the same black color, and the ink color of multiple substrates is consistent after assembly.

[0013] Preferably, the multilayer film is placed on the substrate with the MiniLED chip by hot pressing, using one of a roller pressing process and a flat plate pressing process.

[0014] Preferably, the temperature of the hot roller in the rolling process is 100-200°C, and the pressure is 0.2-2.0MPa. The substrate with the MiniLED chip is placed on the fixture with the MiniLED chip facing outward. The multilayer film is placed on the MiniLED chip through the hot roller and then transferred to the oven for curing.

[0015] Preferably, the flat-plate pressure transfer process is to place the multilayer film on the MiniLED chip, press the fake sticker, place the multilayer film and the MiniLED chip face down on the hot plate, evacuate the closed cavity first and then press it, the pressing temperature is 70-180°C; the vacuuming time is 30-300 seconds; the pressing time is 30-300 seconds; the pressure is 0.2-2Mpa, and after pressing, it is transferred to the oven for curing.

[0016] Preferably, the multi-layer film is provided with a release film on the upper and lower sides respectively. The release film on one side of the black layer is torn off before lamination, and the release film on one side of the translucent layer is torn off after complete curing.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. In the present invention, a multi-layer adhesive film with uniform thickness and uniform black color is first prepared by precision coating technology, and then a good pressing process is used to solve the problems of uniform black color of the MiniLED display module and side light leakage of the module during assembly. At the same time, the problems of large thickness tolerance caused by the use of liquid resin and the black liquid resin covering the top of the MiniLED chip are solved. One-time pressing and molding improves production efficiency and yield.

[0019] 2. In the present invention, the multilayer film must contain a black layer and a translucent layer, while the transparent layer and the hardened hydrophobic layer are selectively arranged to give the film multiple functions; the thickness of the black layer (including the transparent layer arranged under the black layer) is less than the height of the MiniLED chip. After lamination, the black layer (including the transparent layer arranged under the black layer) is filled between the MiniLED chips and between the positive and negative electrode pads to cover the original color of the substrate, giving each substrate the same black color, and achieving ink color consistency after assembling multiple substrates, while improving the contrast; the translucent layer covers the top of the MiniLED chip to isolate it from damage by water vapor, pollutants or corrosive substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram for comparing different layered structures of the multilayer film of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The present invention uses precision coating technology to first coat the resin composition on a roll of release film, and then bake the solvent in an oven to dry the resin into a semi-cured state, and then roll the material. The precision coating technology can accurately control the coating thickness to ±2μm, and the roll-shaped continuous coating production efficiency is high.

[0023] Specifically, the present invention must contain a black layer and a translucent layer. In order to be able to fill the resin under the chip, a transparent layer with the best fluidity under high temperature conditions can be added under the black layer. The thickness of the transparent layer plus the thickness of the black layer is less than the height of the MiniLED chip. Preferably, the sum of the thicknesses of the two layers is 60%-80% of the height of the MiniLED chip. Taking the current mass-produced MiniLED chip height of generally 100μm as an example, the preferred black layer thickness is 40±10μm, and the transparent layer under the black layer is 10±10μm.

[0024] According to needs, the present invention can also add a transparent layer without carbon black between the black layer and the translucent layer. The fluidity of the transparent layer at high temperature is worse than that of the black layer. The black layer residue left on the top of the MiniLED chip can be squeezed out to improve the brightness and visual effect of the MiniLED after lighting. The thickness of this layer should not be too thick, preferably 10-100μm, and the transmittance is 50%-95%.

[0025] The present invention must contain a translucent layer, which contains a small amount of carbon black. This layer and the black layer can effectively reduce the problem of light leakage after the MiniLED substrate is assembled, and slightly reduce the brightness of the MiniLED to reduce the glare. After lamination, this layer covers the entire substrate and is higher than the MiniLED chip by a certain height, thereby protecting the entire substrate and chip from erosion by water vapor and pollutants. The preferred thickness of this layer is 10-300μm, and the transmittance is 30%-90%.

[0026] According to the needs, some application scenarios require the display screen to have higher hardness and hydrophobicity to ensure that it is not easy to leave fingerprints and not scratched by nails. For this purpose, a hardened hydrophobic layer was invented and designed. The specific implementation method is to first apply the hardened hydrophobic layer on the release film, dry the solvent in an oven to enter a semi-cured state, roll it up, and then apply a translucent layer on the layer. Since the hardness of this layer is relatively large and it needs to be rolled up, it is not easy to apply thickly. The preferred coating thickness is 1-20μm, and the hardness after curing is 4-7H.

[0027] First, each layer in the invention is coated into a roll of semi-cured adhesive film, and then combined according to actual application requirements. The combination process is also achieved by roll-to-roll rolling, and continuous production is finally performed. The roll of multi-layer film is die-cut into a sheet with the same shape as the substrate, so as to encapsulate the substrate with the MiniLED chip.

[0028] Specifically, the sheet-like multilayer film and the substrate with the MiniLED chip are hot pressed together by hot pressing. The multilayer film of the present invention is suitable for both roller pressing and flat plate pressing. When using the roller pressing process, the temperature of the hot roller is preferably 100-200°C, and the pressure is preferably 0.2-2.0MPa. The substrate with the MiniLED chip is placed on the fixture, with the MiniLED chip facing outward, and the multilayer semi-cured adhesive film is placed on the MiniLED chip and passed through the hot roller; when using the flat plate pressing process, the multilayer semi-cured film is first placed on the MiniLED chip, and after pressing the fake sticker with the finger, the multilayer film and the MiniLED chip are placed on the hot plate facing down, and the closed cavity is first vacuumed and then pressed; the pressing temperature is preferably 70-180°C; the vacuuming time is preferably 30-300 seconds; the pressing time is preferably 30-300 seconds; the pressure is preferably 0.2-2Mpa. Due to the short pressing time of the two pressing processes, the multilayer film has not been completely cured. After pressing, it is transferred to the oven for curing. The preferred curing process is shown in the following table:

[0029] Phase 1 Phase II Phase 3 Stage 4 Temperature(℃) 120 140 160 Cool down to normal temperature Time (h) 2 2 1 0.5

[0030] After thorough curing, the multilayer film is completely bonded to the MiniLED chip and substrate. The MiniLED chip cannot be corroded by hot and cold shocks, moisture and pollutants, ensuring that the MiniLED chip can be used for a long time.

[0031] Step 1: Laminate the layers and die-cut into sheets according to the table below.

[0032]

[0033]

[0034] Step 2: Lamination

[0035] The embodiment is pressed together with the substrate with the Mini LED chip using a flat plate pressure transfer process. The specific process is as follows: a multi-layer semi-cured film is placed on the Mini LED chip. After pressing the fake sticker, the multi-layer film and the Mini LED chip are placed face down on a hot plate. The closed cavity is first vacuumed and then pressed. The pressing temperature is preferably 70-180°C; the vacuuming time is preferably 30-300 seconds; the pressing time is preferably 30-300 seconds; the pressure is preferably 0.2-2Mpa; after pressing, the film is transferred to an oven for curing.

[0036] Step 3: Curing

[0037] The curing process is shown in the following table:

[0038]

[0039] After cooling to room temperature, tear off the release film, and the multi-layer film packaging of the Mini LED chip substrate is completed. The appearance and performance test are shown in the following table:

[0040]

[0041]

[0042] It should be noted that, in this article, relational terms such as first and second, etc. 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. Moreover, the terms "include", "comprise" or any other variants thereof are 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 other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0043] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A multilayer film for MiniLED packaging, characterized in that: The multilayer film contains at least two layers: a black layer and a translucent layer, and the multilayer film can soften and flow at high temperatures. The black layer fills the space between the MiniLED chips to cover the original color of the substrate, and the translucent layer covers the top of the chip. The black layer is a semi-cured resin composition, and the black layer is pressed between the MiniLED chips and between the positive and negative electrode soldering feet of the chip by hot pressing; The black layer is a semi-cured resin composition added with carbon black, with a transmittance of 0.1%-30% and a thickness of 1-100 μm, and a semi-cured transparent layer is arranged between the black layer and the semi-transparent layer. During the lamination process, the resin of the semi-cured transparent layer can squeeze out the black resin remaining directly above the MiniLED chip. The transmittance of the semi-cured transparent layer is 50%-95%, and the thickness is 10-100 μm. A resin layer is disposed under the black layer, the thickness of the resin layer is 1-30 μm, and the sum of the thickness of the resin layer and the black layer is less than the height of the MiniLED chip; The semi-transparent layer is a resin composition added with carbon black, with a transmittance of 30-90% and a thickness of 10-300 μm; A hardened hydrophobic layer is arranged on the translucent layer. The hardened hydrophobic layer has a thickness of 1-10 μm and a hardness of 5-7H after curing.

2. A method for using a multilayer film for MiniLED packaging, characterized in that: Including the multilayer film as described in claim 1, the multilayer film is placed on the substrate with the MiniLED chip by hot pressing. After heating and curing, the multilayer film covers the original color of the substrate, giving each substrate the same black color, and the ink color of multiple substrates is consistent after assembly.

3. The method for using a multilayer film for MiniLED packaging according to claim 2, characterized in that: Including the multilayer film as described in claim 1, the multilayer film is placed on a substrate with a MiniLED chip by hot pressing, and one of a roller pressing process and a flat plate pressure transfer process is selected.

4. The method for using a multilayer film for MiniLED packaging according to claim 3, characterized in that: Including the multilayer film as described in claim 1, the temperature of the hot roller in the rolling process is 100-200°C, the pressure is 0.2-2.0MPa, the substrate with the MiniLED chip is placed on the fixture, the MiniLED chip faces outward, the multilayer film is placed on the MiniLED chip through the hot roller, and then transferred to the oven for curing.

5. The method for using a multilayer film for MiniLED packaging according to claim 4, characterized in that: Including the multilayer film as described in claim 1, the flat-plate pressure transfer process is to place the multilayer film on the MiniLED chip, press the fake sticker, place the multilayer film and the MiniLED chip face down on the hot plate, close the cavity, evacuate the vacuum first and then press it, the pressing temperature is 70-180°C; the vacuum time is 30-300 seconds; the pressing time is 30-300 seconds; the pressure is 0.2-2Mpa, and after pressing, it is transferred to the oven for curing.

6. The method for using a multilayer film for MiniLED packaging according to claim 5, characterized in that: The multilayer film comprises the multilayer film as claimed in claim 1, wherein a release film is respectively provided on the upper and lower sides of the multilayer film, and the release film on one side of the black layer is torn off before lamination, and the release film on one side of the translucent layer is torn off after complete curing.

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