Polycrystal display device and preparation method thereof

Abstract

The invention provides a polycrystalline display device and a preparation method thereof, and the preparation method comprises the steps: placing a light-emitting structure which is provided with a first reflection glue layer at the periphery of an LED chip on the surface of a first supporting film; each LED chip is provided with a light-emitting upper surface, a light-emitting side surface and an electrode surface opposite to the light-emitting upper surface, and the light-emitting upper surfaces of the LED chips on the surface of the first supporting film face upwards; the upper surface of the first reflecting glue layer is flush with the light-emitting upper surfaces of the LED chips, and a plurality of LED chips corresponding to at least one polycrystalline display device are regularly arranged in the light-emitting structure; the light conversion layers are attached to the surfaces of LED chips corresponding to the polycrystalline display device respectively; the light conversion layer comprises fluorescent film layers matched with the LED chips one by one, and second reflective glue layers formed around the fluorescent film layers; and cutting along the cutting channels between the adjacent polycrystalline light-emitting structures to obtain the polycrystalline display device. The problem that an existing polycrystalline display device is uneven in light emitting is effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a polycrystalline display device and a preparation method thereof. Background Art

[0002] In polycrystalline CSP (chip scale package) products, during preparation, it is usually necessary to arrange LED chips on the surface of a first support film (such as a UV film, etc.), and then perform an operation of attaching a fluorescent film to each LED chip. Under this packaging method, affected by the placement accuracy, problems such as Figure 1 as shown, the fluorescent film 1 rotates, etc., making it very difficult to make the light source centers of adjacent LED chips consistent; and the distance between adjacent LED chips cannot be further reduced. Based on this, after forming a lens on the surface of the polycrystalline CSP product, there will be a very obvious problem of alternating light and dark in the light pattern, seriously affecting the product application. Summary of the Invention

[0003] In order to overcome the above deficiencies, the present invention provides a polycrystalline display device and a preparation method thereof, effectively solving the problem of uneven light emission of existing polycrystalline display devices.

[0004] The technical solution provided by the present invention is as follows: On the one hand, the present invention provides a preparation method of a polycrystalline display device, including: Placing a light-emitting structure with a first reflective adhesive layer around the LED chips on the surface of the first support film; the LED chips have a light-emitting upper surface, a light-emitting side surface, and an electrode surface opposite to the light-emitting upper surface, and on the surface of the first support film, the light-emitting upper surfaces of the LED chips face upward; the upper surface of the first reflective adhesive layer is flush with the light-emitting upper surface of the LED chips, and at least one plurality of LED chips corresponding to the polycrystalline display device are regularly arranged in the light-emitting structure, and the LED chips in the same polycrystalline display device form a polycrystalline light-emitting structure; Attaching a light conversion layer to the surface of the LED chips corresponding to the polycrystalline display device respectively; the light conversion layer includes a fluorescent film layer that is matched with the LED chips one by one, and a second reflective adhesive layer formed around the fluorescent film layer, and each polycrystalline display device corresponds to a light conversion layer; Cutting along the cutting channels between adjacent polycrystalline light-emitting structures to obtain the polycrystalline display device.

[0005] On the other hand, the present invention provides a polycrystalline display device prepared by using the above preparation method of the polycrystalline display device, and the polycrystalline display device includes: A plurality of regularly arranged LED chips; A light conversion layer formed on the surface of the plurality of LED chips, the light conversion layer includes a fluorescent film layer that is matched with the LED chips one by one, and a second reflective adhesive layer formed around the fluorescent film layer; and The first reflective adhesive layer disposed around the LED chip.

[0006] The polycrystalline display device and its manufacturing method provided by the present invention encapsulate the polycrystalline display device by prefabricating a light conversion layer including a fluorescent film layer and a second reflective adhesive layer, solve the problems of inconsistent luminous center spacing between LED chips and excessive gaps between LED chips, improve the light pattern uniformity of the polycrystalline display device, and simultaneously reduce the luminous area of the entire polycrystalline display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Schematic diagram showing rotation after pasting the fluorescent film sheet in the prior art; Figure 2 Top view schematic diagram of the light-emitting structure in an example of the present invention; Figure 3 For Figure 2 Cross-sectional schematic diagram of the structure shown in the A-A direction; Figure 4 Schematic diagram of the structure of the present invention with the light conversion layer pasted on the surface of the corresponding LED chip of the light-emitting structure; Figure 5 Cross-sectional schematic diagram of the structure of a polycrystalline display device of the present invention; Figure 6 For Figure 5 Top view schematic diagram of the structure shown; Figure 7 Schematic diagram of the structure of the present invention with a fluorescent film layer formed on the second support film; Figure 8 Schematic diagram of the structure of the present invention with the fluorescent film layer cut to form a notch; Figure 9 Schematic diagram of the structure of the present invention with a second reflective adhesive layer formed in the fluorescent film layer; Figure 10 Schematic diagram of the structure of the present invention with the fluorescent film layer cut to form a light conversion layer; Figure 11 Cross-sectional schematic diagram of a light conversion layer of the present invention; Figure 12 For Figure 11 Top view schematic diagram of the structure shown.

[0008] Reference numerals: 1 - Fluorescent film sheet, 2 - First support film, 3 - LED chip, 4 - First reflective adhesive layer, 5 - Polycrystalline light-emitting structure, 6 - Light conversion layer, 7 - Fluorescent film layer, 8 - Second reflective adhesive layer, 9 - Second support film, 10 - Notch. DETAILED DESCRIPTION OF THE INVENTION

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, and other embodiments can also be obtained.

[0010] The first embodiment of the present invention is a method for preparing a polycrystalline display device, including: S10. Place a light-emitting structure with a first reflective adhesive layer around an LED chip on the surface of a first support film; the LED chip has a light-emitting upper surface, a light-emitting side surface, and an electrode surface opposite to the light-emitting upper surface, and the light-emitting upper surfaces of the LED chips on the surface of the first support film face upward. The LED chips in the same polycrystalline display device form a polycrystalline light-emitting structure; the upper surface of the first reflective adhesive layer is flush with the light-emitting upper surface of the LED chip. In the light-emitting structure, at least multiple LED chips corresponding to one polycrystalline display device are regularly arranged. In the example where the LED chips in the polycrystalline display device are arranged in a 5×5 matrix, place a light-emitting structure with a first reflective adhesive layer 4 around an LED chip 3 on the surface of a first support film 2 as Figure 2 and 3 shown, where Figure 2 is a top view schematic diagram, Figure 3 is Figure 2 a cross-sectional schematic diagram in the A-A direction in

[0011] After forming a first reflective adhesive layer around the LED chip, it is placed on the surface of the first support film. The upper surface of the first reflective adhesive layer is flush with the light-emitting upper surface of the LED chip, and the lower surface is flush with the electrode surface of the LED chip. The material of the first reflective adhesive layer is a mixture of resin and light-reflective particles. The resin can be a thermosetting resin such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., preferably thermosetting silicone resin and epoxy resin. The light-reflective particles are generally white inorganic pigments, such as oxides like titanium oxide, zinc oxide, zirconium oxide, carbonates like lead white (lead carbonate), calcium carbonate, and clay minerals like kaolin (kaolinite), etc., preferably titanium oxide. The purpose of forming the first reflective adhesive layer around the light-emitting side of the LED chip is to prevent light emission from the side. Therefore, in application, it is necessary to adjust the doping ratio of the light-reflective particles according to the actual situation to make it have a high reflectivity with a reflectivity reaching a preset value (such as 80%, 90%, 95%, etc.) or more.

[0012] The function of the first support film is to support the light-emitting structure and facilitate subsequent encapsulation processes. It can be a film such as a UV film (ultraviolet irradiation tape) that is easy to peel off after encapsulation. In actual production, there are at least one or more LED chips corresponding to each polycrystalline display device regularly arranged in the light-emitting structure. To improve the encapsulation efficiency, it usually includes multiple (the number is not specifically limited, such as 2, 4, 8, or even more) polycrystalline display devices, that is, encapsulating the polycrystalline display devices in batches and arranging them regularly in the light-emitting structure. As Figure 2 shown in the figure, the polycrystalline light-emitting structures 5 corresponding to 4 polycrystalline display devices are arranged in an array to form the light-emitting structure. In addition, the light-emitting type, chip size, etc. of the LED chips included in the polycrystalline display device are not specifically limited in this embodiment. The same model of LED chips can be encapsulated uniformly, or LED chips of different sizes can be encapsulated, or even LED chips of different sizes with different light-emitting types can be encapsulated. As long as they are arranged regularly based on the encapsulation method of this embodiment for easy encapsulation.

[0013] Before step S10, it also includes the step of forming the light-emitting structure: S01. Regularly arrange the LED chips on the surface of the third support film with the electrode surface facing upward.

[0014] The function of the third support film is to support the LED chips and facilitate subsequent encapsulation processes. It can be a film such as a UV film that is easy to peel off after encapsulation. Each LED chip is arranged according to the encapsulation structure of the polycrystalline display device. For example, in one instance, the LED chips in a single polycrystalline display device are arranged in a 5*5 matrix array; in another embodiment, the LED chips in a single polycrystalline display device are arranged in a 2*6 array.

[0015] S02. Fill the light-reflecting material between the LED chips and bake.

[0016] The upper surface of the light-reflecting material after filling and flowing flat is at least the electrode surface of the LED chip, and generally covers the entire LED chip. The baking conditions are determined according to the actual situation, such as baking at 150 °C for 2 h (hours).

[0017] S03. Grind the light-reflecting material on the surface of the LED chip until the chip electrode is exposed to form a light-emitting structure. On this basis, in step S10, the light-emitting structure with a reflective adhesive layer provided around the LED chip is placed on the surface of the first support film, including: flipping the light-emitting structure from the third support film to the surface of the first support film and removing the third support film.

[0018] S20. Attach the light conversion layer to the surface of the corresponding LED chip of the polycrystalline display device respectively; the light conversion layer includes a fluorescent film layer that matches the LED chip one by one, and a second reflective adhesive layer formed around the fluorescent film layer, and each polycrystalline display device corresponds to a light conversion layer. As Figure 4 shown, the light conversion layer 6 includes a fluorescent film layer 7 and a second reflective adhesive layer 8. The position of the fluorescent film layer 7 corresponds to the LED chip in the polycrystalline display device one by one, and the second reflective adhesive layer 8 is disposed between the fluorescent film layers corresponding to adjacent LED chips.

[0019] The light conversion layer is disposed on the surface above the light emission of the LED chip. The wavelength conversion material in the fluorescent film layer converts the transmitted light into another wavelength. The wavelength conversion material is a phosphor that can be excited by the light emitted by the LED chip. In this way, a display device with a different light color from the light emitted by the LED chip is obtained, and the thickness is 70 μm to 120 μm. The composition of the wavelength conversion material can be at least one or more of the following: garnet-type phosphor, oxynitride phosphor, aluminate phosphor, nitride phosphor, sulfide phosphor, KSF phosphor, etc.

[0020] The material of the second reflective adhesive layer is similar to that of the first reflective adhesive layer and is a mixture of resin and light-reflective particles. The resin can be a thermosetting resin such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., preferably thermosetting silicone resin and epoxy resin. The light-reflective particles are generally white inorganic pigments, such as oxides such as titanium oxide, zinc oxide, zirconium oxide, carbonates such as lead white (lead carbonate), calcium carbonate, and clay minerals such as kaolin (kaolinite), etc., preferably titanium oxide. The purpose of forming the second reflective adhesive layer around the side of the fluorescent film layer is to prevent light from emitting from the side. Therefore, in application, it is necessary to adjust the doping ratio of the light-reflective particles according to the actual situation so that it has a high reflectivity with a reflectivity reaching a preset value (such as 80%, 90%, 95%, etc.) or more. The materials used, doping ratio, etc. of the second reflective adhesive layer can be the same as or different from those of the first reflective adhesive layer, as long as the invention purpose can be achieved.

[0021] For the mounting method of the light conversion layer, any existing method can be adopted, such as vacuum lamination, etc. In order to improve the chip mounting accuracy of the light conversion layer, in one embodiment, the light conversion layer is attached to the surface of the corresponding LED chip of the polycrystalline display device, including: First, an incompletely cured adhesive layer is formed on the surface of the light-emitting structure, and the adhesive layer is close to the light-emitting upper surface of the LED chip; After that, the light conversion layer is respectively attached to the surface of the corresponding adhesive layer of the polycrystalline display device and cured.

[0022] In this embodiment, the material used for the adhesive layer can be a thermosetting resin such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., preferably thermosetting silicone resin and epoxy resin. The function of this adhesive layer is to adhere the light conversion layer. Therefore, after the material of the adhesive layer is coated on the light-emitting upper surface of the LED chip, it is dried to an incompletely cured state. Here, the incompletely cured specifically means that the adhesive layer is not completely cured, so that it has sufficient viscosity to adhere the light conversion layer. Compared with the curing conditions of the completely cured adhesive layer, this incompletely cured state can be achieved by shortening the baking time and / or reducing the baking temperature. After the light conversion layer is attached to the surface of this adhesive layer, it is further baked to cure it, and the film laminating operation of the light conversion layer is completed. Based on the function of this adhesive layer, in order not to affect the light emission of the polycrystalline display device, it is limited that the thickness of this adhesive layer is relatively thin, such as a thickness of 1 µm, 2 µm, 5 µm, etc., and it should not exceed 10 µm (micrometer).

[0023] The preparation method of the light conversion layer is described below: In one embodiment, the preparation process of the light conversion layer includes: S21. Provide a second support film.

[0024] The function of the second support film is as a light conversion layer, which facilitates the subsequent encapsulation process and can be a film such as a UV film that is easy to peel off after encapsulation.

[0025] S22. Form a layer of fluorescent film layer on the surface of the second support film and cure it into shape. The surface on the side away from the second support film is the upper surface. As Figure 7 shown, the fluorescent film layer 7 is formed on the surface of the second support film 9.

[0026] In this step, the fluorescent material and the resin material are uniformly mixed and then coated on the surface of the second support film and cured into shape. The fluorescent material, resin material and their mixing ratio used need to be determined according to the application requirements and are not limited here.

[0027] S23. Cut the fluorescent film layer according to the arrangement of the LED chips in the polycrystalline display device, and form notches between the fluorescent film layers corresponding to adjacent LED chips. As Figure 8 shown, a plurality of notches 10 are formed in the fluorescent film layer 7, and the shape of the notches is set according to the size and shape of the LED, and a whole fluorescent film is isolated into individual small fluorescent films.

[0028] Since the LED chips in the polycrystalline display device are usually arranged in a regular matrix, the fluorescent film layer can be cut based on this arrangement. In order to ensure the light pattern of the light output, notches are formed along the middle position between the fluorescent film layers corresponding to adjacent LED chips, and the width of the formed notches is smaller than the gap width between adjacent LED chips, ensuring that the area of the light conversion layer formed above the light-emitting surface of the LED chip is larger than the area of the light-emitting surface of the LED chip. Compared with the method of pasting a fluorescent film piece for each LED chip alone, the method of forming a light conversion layer for pasting is less affected by the accuracy of the mounter. Therefore, the ratio of the area of the light conversion layer to the area of the light-emitting surface of the LED chip can be made smaller, approaching 1:1 (in a conventional single CSP chip, the area ratio of the light conversion layer to the light-emitting surface of the LED chip reaches 1.2:1 or even larger), thereby further reducing the light output area of the entire polycrystalline display device. In one example, the ratio of the area of the light conversion layer to the area of the light-emitting surface of the LED chip is 1.05:1.

[0029] S24. Fill the formed notches with a light-reflecting glue and cure it into shape to form a second reflective glue layer, and the upper surface of the second reflective glue layer is flush with the upper surface of the fluorescent film layer. As Figure 9 shown, the second reflective glue layer 8 formed after filling the notches with the light-reflecting glue is located between the fluorescent film layers 7 corresponding to the LED chips, and the upper surface of the second reflective glue layer 8 is flush with the upper surface of the fluorescent film layer.

[0030] Generally speaking, the light-reflecting glue filled in the slot has a certain fluidity and is placed in the slot by dispensing. In order to prevent the upper surface of the filled light-reflecting glue from exceeding the upper surface of the light conversion layer after curing, after the light-reflecting glue is cured, a grinding and polishing operation is further performed to remove the excess light-reflecting glue.

[0031] S25. Cut to obtain the light conversion layer for a single polycrystalline display device. As Figures 10 - 12 shown, the obtained light conversion layer 6 after cutting includes a fluorescent film layer 7 and a second reflective glue layer 8. There is a certain proportional relationship between the size of the fluorescent film layer in the light conversion layer and the size of the LED chips in the polycrystalline display device, and the arrangement mode of the fluorescent film layer in the light conversion layer is the same as the arrangement mode of the LED chips in the polycrystalline display device.

[0032] After cutting to obtain the light conversion layer for the polycrystalline display device, peel it off from the surface of the second support film for later use. If a UV film is used, it can be peeled off by irradiating ultraviolet light. After cutting and peeling off the second support film, the obtained Figure 11 and Figure 12 ( Figure 11 is the structural schematic diagram of the light conversion layer of this embodiment, Figure 12 is Figure 11 the top view schematic diagram of the structure shown) the light conversion layer.

[0033] Since in step S23, before cutting the fluorescent film layer, it adheres to the surface of the second support film, after cutting to form the slot, the reflective glue can be directly filled in the slot and cured to obtain the second reflective glue layer.

[0034] In another embodiment, in order to further improve the chip mounting accuracy, step S22 of forming a fluorescent film layer on the surface of the second support film and curing and forming further includes: S221 forming a transparent protective layer on the surface of the second support film; S222 forming a fluorescent film layer on the surface of the transparent protective layer and curing and forming.

[0035] In this embodiment, before coating the fluorescent film layer, a transparent protective layer is first formed on the surface of the second support film, and the two layers are cured together. During the process of cutting the fluorescent film layer to form the slot, it is ensured that after cutting the fluorescent film layer to the transparent protective layer (only cutting the fluorescent film layer), the positions of the fluorescent film layers corresponding to each LED chip will not move. Then, the obtained light conversion layer for a single polycrystalline display device is respectively pasted on the surface of the LED chips corresponding to the polycrystalline display device. The opening side of the slot of the light conversion layer is facing the LED chips and pasted on the surface of the LED chips corresponding to the polycrystalline display device and cured and formed. The light conversion layer includes a fluorescent film layer that matches the LED chips one by one, a second reflective glue layer formed around the fluorescent film layer, and a transparent protective layer formed on the surfaces of the fluorescent film layer and the second reflective glue layer.

[0036] Finally, in step S30, cutting is performed along the dicing streets between adjacent polycrystalline light-emitting structures corresponding to adjacent polycrystalline display devices. The obtained polycrystalline display device includes multiple LED chips arranged regularly, a light conversion layer formed on the surfaces of the multiple LED chips, and a first reflective adhesive layer surrounding the LED chips on all sides. As Figure 5 and Figure 6 ( Figure 5 is a schematic cross-sectional view of the structure of the polycrystalline display device of this embodiment, Figure 6 and Figure 5 as shown in the top view schematic diagram of the structure shown), the polycrystalline display device includes multiple LED chips 3. In fact, in the top view schematic diagram of this polycrystalline display device, 25 LED chips 3 are arranged in a 5×5 matrix. The first reflective adhesive layer 4 is filled between the LED chips. The light conversion layer 6 is formed on the surface above the light-emitting surface of the LED chips. The size and position of the fluorescent film layer 7 in the light conversion layer correspond to the LED chips one by one. The second reflective adhesive layer 8 in the light conversion layer is formed between the fluorescent film layers corresponding to adjacent LED chips. When the light conversion layer includes a transparent protective layer, in addition to the structure of multiple regularly arranged LED chips, a light conversion layer formed on the surfaces of the multiple LED chips, and a first reflective adhesive layer surrounding the LED chips on all sides, the polycrystalline display device also has a transparent protective layer formed on the surface of the light conversion layer. In another embodiment, in order to further improve the chip mounting accuracy, in step S23, the fluorescent film layer is cut according to the arrangement mode of the LED chips in the polycrystalline display device, and a groove is formed between the fluorescent film layers corresponding to adjacent LED chips. Part of the fluorescent film layer is cut, and the cutting depth is the thickness value of the light conversion layer on the surface of the polycrystalline display device (at this time, the thickness of the fluorescent film layer is greater than the thickness of the light conversion layer). On this basis, in step S20, attaching the light conversion layer to the surfaces of the corresponding LED chips of the polycrystalline display device respectively includes: attaching the light conversion layer to the surfaces of the corresponding LED chips of the polycrystalline display device with the opening side of the groove of the light conversion layer facing the LED chips and curing and forming; grinding the surface of the light conversion layer away from the LED chips to remove the uncut thickness part of the fluorescent film layer during the formation of the groove, so that there is no interconnected part between the fluorescent film layers in the finally formed light conversion layer, and each fluorescent film layer in the light conversion layer is independent of each other..

[0037] In this embodiment, the fluorescent film layer formed on the surface of the second support film is thicker than the surface light conversion layer of the polycrystalline display device. The thickness difference can be adjusted according to the process, such as controlling the cutting of 2 / 3 of the fluorescent film layer. In this way, after the fluorescent film layer is cut to form a notch, the fluorescent film layer remains an integral body, ensuring the relative positional relationship between each LED chip and the corresponding fluorescent film layer. After that, after the light conversion layer is attached to the surface of the LED chip, the uncut and interconnected thickness part of the fluorescent film layer can be ground and removed. On this basis, after step S20 attaches the light conversion layer to the corresponding LED chips on the polycrystalline display device respectively, a transparent protective layer is formed on the surface of the light conversion layer, obtaining a polycrystalline display device including a plurality of regularly arranged LED chips, a light conversion layer formed on the surfaces of the plurality of LED chips, a first reflective adhesive layer surrounding the LED chips, and a transparent protective layer formed on the surface of the light conversion layer.

[0038] In the above embodiment, the transparent protective layer covers the surface of the light conversion layer, is used to protect the light conversion layer and has light transmittance at the same time. The light converted by the light conversion layer is emitted through this protective layer, and the thickness is 100 μm to 400 μm. The material can be a thermosetting resin, such as silicone resin, epoxy resin, polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, etc., one or more of them, preferably silicone resin and epoxy resin.

[0039] Another embodiment of the present invention is a polycrystalline display device prepared by using the above preparation method of the polycrystalline display device. The polycrystalline display device includes: a plurality of regularly arranged LED chips; a light conversion layer formed on the surfaces of the plurality of LED chips, the light conversion layer includes a fluorescent film layer that is matched with the LED chips one by one, and a second reflective adhesive layer formed around the fluorescent film layer; and a first reflective adhesive layer surrounding the LED chips.

[0040] In this embodiment, the light conversion layer is disposed on the surface above the light emission of the LED chip. The wavelength conversion material in the fluorescent film layer converts the transmitted light into another wavelength. The wavelength conversion material is a phosphor that can be excited by the light emitted by the LED chip, so as to obtain a display device with a different light color from the light emitted by the LED chip, and the thickness is 70 μm to 120 μm. The composition of the wavelength conversion material can be at least one or more of the following: garnet-type phosphor, oxynitride phosphor, aluminate phosphor, nitride phosphor, sulfide phosphor, KSF phosphor, etc.

[0041] The upper surface of the first reflective adhesive layer is flush with the light-emitting upper surface of the LED chip, and the lower surface is flush with the electrode surface of the LED chip. The material of the first reflective adhesive layer is a mixture of resin and light-reflecting particles. The resin can be a thermosetting resin such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., preferably thermosetting silicone resin and epoxy resin. The light-reflecting particles are generally white inorganic pigments, such as oxides such as titanium oxide, zinc oxide, zirconium oxide, carbonates such as lead white (lead carbonate), calcium carbonate, and clay minerals such as kaolin (kaolinite), etc., preferably titanium oxide. The purpose of forming the first reflective adhesive layer around the light-emitting side of the LED chip is to prevent light from emitting from the side. Therefore, in application, it is necessary to adjust the doping ratio of the light-reflecting particles according to the actual situation so that it has a high reflectivity with a reflectivity reaching a preset value (such as 80%, 90%, 95%, etc.) or more. The materials, doping ratios, etc. used for the second reflective adhesive layer can be the same as or different from those of the first reflective adhesive layer, as long as the invention purpose can be achieved.

[0042] In order to ensure the light pattern of the emitted light, the width between the corresponding fluorescent film layers of adjacent LED chips is smaller than the gap width between adjacent LED chips, ensuring that the area of the light conversion layer formed on the light-emitting upper surface of the LED chip is larger than the area of the light-emitting upper surface of the LED chip. Compared with the method of attaching a fluorescent film piece to each LED chip separately, the method of forming a light conversion layer for attachment is less affected by the accuracy of the mounter. Therefore, the ratio of the area of the light conversion layer to the area of the light-emitting upper surface of the LED chip can be made smaller, approaching 1:1 (in a conventional single CSP chip, the area ratio of the light conversion layer to the light-emitting upper surface of the LED chip reaches 1.2:1 or even larger), thereby further reducing the light-emitting area of the entire polycrystalline display device. In one example, the ratio of the area of the light conversion layer to the area of the light-emitting upper surface of the LED chip is 1.05:1.

[0043] In this embodiment, the light-emitting type, chip size, etc. of the LED chips included in the polycrystalline display device are not specifically limited. The same model of LED chips can be uniformly packaged, or LED chips of different sizes can be packaged, or even different sizes of LED chips of different light-emitting types can be packaged. As long as they are arranged regularly based on the packaging method of this embodiment, it is convenient for packaging.

[0044] Improving the above embodiment, in this embodiment, the polycrystalline display device includes a plurality of regularly arranged LED chips; a light conversion layer formed on the surface of the plurality of LED chips, the light conversion layer includes a fluorescent film layer that matches the LED chips one by one, and a second reflective adhesive layer formed around the fluorescent film layer; and in addition to the first reflective adhesive layer surrounding the LED chips on all sides, it further includes: a bonding adhesive layer formed between the LED chip and the light conversion layer; or a transparent protective layer formed on the surface of the light conversion layer.

[0045] In this embodiment, the material used for the adhesive layer can be thermosetting resins such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc. Thermosetting silicone resin and epoxy resin are preferred. The function of this adhesive layer is to adhere to the light conversion layer. In order not to affect the light output of the polycrystalline display device, the thickness of the adhesive layer is limited to be relatively thin, such as 1 µm, 2 µm, 5 µm, etc., and should not exceed 10 µm.

[0046] The transparent protective layer covers the surface of the light conversion layer, has light transmittance while protecting the light conversion layer, and the light converted by the light conversion layer is emitted through this protective layer, with a thickness of 100 µm to 400 µm. The material can be a curable resin, such as one or more of silicone resin, epoxy resin, polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, etc. Silicone resin and epoxy resin are preferred.

[0047] In the above embodiment, the emission color, size, etc. of the LED chips in the polycrystalline display device are not specifically limited. In actual applications, the LED chips can be arranged according to the emission requirements, and it is only necessary to facilitate grooving and encapsulation between the LED chips. In Figure 12 In the polycrystalline display device shown, 25 LED chips 3 with inconsistent sizes are encapsulated in a polycrystalline display device in a 5×5 matrix arrangement. In other examples, they can be encapsulated in any combination according to this method. For the convenience of encapsulation, in the array arrangement of LED chips with different sizes, the LED chips in the same row have the same size in the column direction, and the LED chips in the same column have the same size in the row direction. If the size in the row direction is defined as the chip length and the size in the column direction is defined as the chip width, then the chip widths of the LED chips in the same row are the same, and the chip lengths of the LED chips in the same column are the same.

[0048] In the above embodiments, the pitch between the LED chips in the polycrystalline display device and the pitch between adjacent fluorescent film sheets can be reduced to a certain extent, thereby reducing the packaging size and the overall light-emitting area of the polycrystalline display device. In one example, the polycrystalline display device includes 9 LED chips with a size of 40 mil (1000 μm) arranged in a 3*3 matrix. The ratio of the area of the fluorescent film layer to the light-emitting upper area of the LED chips is 1.1:1. After packaging by the above preparation method, the pitch between adjacent LED chips in the conventional packaging can be reduced from 400 μm to 200 μm, and the light-emitting edge pitch (the pitch between the fluorescent film layers on the surfaces of adjacent LED chips) can be reduced from 100 μm to 20 μm. The size of the overall module is reduced from 4400 μm * 4400 μm to 3640 μm * 3640 μm, and the light-emitting area is reduced from 4100 μm * 4100 μm to 3340 μm * 3340 μm.

[0049] It should be noted that the above embodiments can be freely combined as needed. The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a polycrystalline display device, characterized in that, Comprising: Placing a light-emitting structure with a first reflective adhesive layer around an LED chip on the surface of a first support film; the LED chip has a light-emitting upper surface, a light-emitting side surface, and an electrode surface opposite to the light-emitting upper surface, and the light-emitting upper surfaces of the LED chips on the surface of the first support film face upward; the upper surface of the first reflective adhesive layer is flush with the light-emitting upper surface of the LED chip, and at least one plurality of LED chips corresponding to a polycrystalline display device are regularly arranged in the light-emitting structure, and the LED chips in the same polycrystalline display device form a polycrystalline light-emitting structure; Attaching a light conversion layer to the surfaces of the LED chips corresponding to the polycrystalline display device respectively; the light conversion layer includes a fluorescent film layer that matches the LED chips one by one, and a second reflective adhesive layer formed around the fluorescent film layer, and each polycrystalline display device corresponds to a light conversion layer; Performing cutting along the cutting channels between adjacent polycrystalline light-emitting structures to obtain polycrystalline display devices, and the cutting channels are located in the second reflective adhesive layer between adjacent polycrystalline light-emitting structures.

2. The method for manufacturing a polycrystalline display device according to claim 1, wherein In the step of attaching the light conversion layer to the surfaces of the LED chips corresponding to the polycrystalline display device respectively, it includes: Forming an incompletely cured adhesive layer on the surface of the light-emitting structure, and the adhesive layer is close to the light-emitting upper surface of the LED chip; Attaching the light conversion layer to the surfaces of the adhesive layers corresponding to the polycrystalline display device respectively and curing.

3. The method for preparing a polycrystalline display device according to claim 1 or 2, characterized in that, The method for preparing a polycrystalline display device further includes the step of preparing a light conversion layer, including: Providing a second support film; Forming a layer of fluorescent film layer on the surface of the second support film and curing it into a shape, and the surface on the side away from the second support film is the upper surface; Cutting the fluorescent film layer according to the arrangement mode of the LED chips in the polycrystalline display device, and forming notches between the fluorescent film layers corresponding to adjacent LED chips; Filling a light-reflective adhesive into the formed notches and curing it into a shape to form a second reflective adhesive layer, and the upper surface of the second reflective adhesive layer is flush with the upper surface of the fluorescent film layer; Cutting to obtain a light conversion layer for a single polycrystalline display device.

4. The method for preparing a polycrystalline display device according to claim 3, wherein In the step of cutting the fluorescent film layer according to the arrangement mode of the LED chips in the polycrystalline display device and forming notches between the fluorescent film layers corresponding to adjacent LED chips, notches are formed along the middle position between the fluorescent film layers corresponding to adjacent LED chips, and the width of the formed notches is smaller than the gap width between adjacent LED chips.

5. The method for preparing a polycrystalline display device according to claim 3, wherein In the step of forming a layer of fluorescent film layer on the surface of the second support film and curing it into a shape, it includes: forming a transparent protective layer on the surface of the second support film; and forming a layer of fluorescent film layer on the surface of the transparent protective layer and curing it into a shape; In the step of cutting the fluorescent film layer according to the arrangement mode of the LED chips in the polycrystalline display device, the fluorescent film layer is cut to the transparent protective layer; The light conversion layer is respectively attached to the surfaces of the LED chips corresponding to the polycrystalline display device. The opening side of the notch of the light conversion layer is oriented towards the LED chip and attached to the surface of the LED chip corresponding to the polycrystalline display device and cured into a shape. The light conversion layer includes a fluorescent film layer that is matched with the LED chip one by one, a second reflective adhesive layer formed around the fluorescent film layer, and a transparent protective layer formed on the surfaces of the fluorescent film layer and the second reflective adhesive layer.

6. The method for manufacturing a polycrystalline display device according to claim 3, wherein, The fluorescent film layer is cut according to the arrangement of the LED chips in the polycrystalline display device. A notch is formed between the fluorescent film layers corresponding to adjacent LED chips. Part of the fluorescent film layer is cut, and the cutting depth is the thickness value of the light conversion layer on the surface of the polycrystalline display device. The step of respectively attaching the light conversion layer to the surfaces of the LED chips corresponding to the polycrystalline display device includes: The opening side of the notch of the light conversion layer is oriented towards the LED chip and attached to the surface of the LED chip corresponding to the polycrystalline display device and cured into a shape. The surface of the light conversion layer away from the LED chip is polished to remove the fluorescent film layer that is not cut during the formation of the notch.

7. The method for manufacturing a polycrystalline display device according to claim 6, wherein, After the light conversion layer is respectively attached to the surfaces of the LED chips corresponding to the polycrystalline display device, the method further includes: the step of forming a transparent protective layer on the surface of the light conversion layer.

8. The method for preparing a polycrystalline display device according to claim 1 or 2 or 4 or 5 or 6 or 7, characterized in that, Before placing the light-emitting structure with the first reflective adhesive layer disposed around the LED chip on the surface of the first support film, it includes: The LED chips are regularly arranged on the surface of the third support film, and the electrode surfaces of the LED chips face upwards. A light-reflective material is filled between the LED chips and baked. The light-reflective material on the surface of the LED chip is polished until the chip electrodes are exposed to form a light-emitting structure. The step of placing the light-emitting structure with the reflective adhesive layer disposed around the LED chip on the surface of the first support film includes: flipping the light-emitting structure from the third support film to the surface of the first support film.

9. A polycrystalline display device, characterized in that, Prepared by using the preparation method of the polycrystalline display device according to any one of claims 1-8, the polycrystalline display device includes: Multiple regularly arranged LED chips; A light conversion layer formed on the surfaces of the multiple LED chips. The light conversion layer includes a fluorescent film layer that is matched with the LED chip one by one, and a second reflective adhesive layer formed around the fluorescent film layer; and A first reflective adhesive layer disposed around the LED chips.

10. The polycrystalline display device according to claim 9, wherein, The polycrystalline display device further includes: an adhesive layer formed between the LED chip and the light conversion layer; or a transparent protective layer formed on the surface of the light conversion layer.

11. The polycrystalline display device according to claim 9 or 10, characterized in that, The polycrystalline display device includes LED chips of multiple sizes.

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