A small-pitch display screen and a production process thereof

Abstract

The application relates to the technical field of light-emitting devices, and discloses a small-pitch display screen and a production process thereof, which comprises a light-emitting device, the light-emitting device comprises a flip chip and a light-emitting film, the light-emitting film covers the top surface and the outer periphery of the flip chip, the bottom surface of the flip chip is connected with two spaced conductive sheet units, the flip chip comprises two electrodes, one electrode is electrically connected with one conductive sheet unit, the edge of the conductive sheet unit extends along the outer side direction of the flip chip, and the edge of the conductive sheet unit is arranged to protrude from the outer periphery of the flip chip. The small-pitch display screen and the production process thereof improve the light-emitting angle uniformity of the micro light-emitting device, increase the light-emitting angle, improve the product yield, and reduce the difficulty of repair.

Description

Technical Field

[0001] This invention relates to the technical field of light-emitting devices, and in particular to a small-pitch display screen and its manufacturing process. Background Technology

[0002] Currently, the small chip size used in the production of small-pitch displays leads to smaller electrode sizes, requiring higher precision equipment and more skilled technicians in the overall mounting process, thus increasing the difficulty of rework. Furthermore, the overall potting and encapsulation process makes it difficult to control the uniformity of light emission.

[0003] Due to the small chip size, when multiple chips are densely arranged on a PCB board, the limited operating space increases the difficulty of connecting the chip electrodes to the PCB board, resulting in a lower yield rate.

[0004] The existing chip is mounted on a bracket, which surrounds the outer periphery of the chip. Due to the bracket, the chip's light emission angle is limited, resulting in a small light emission angle. Summary of the Invention

[0005] The purpose of this invention is to provide a small-pitch display screen and its manufacturing process, which improves the uniformity of the light emission angle of micro-light-emitting devices, increases the light emission angle, improves the product yield, and reduces the difficulty of rework.

[0006] To achieve the above objectives, the present invention provides a small-pitch display screen, including a light-emitting device. The light-emitting device includes a flip chip and a light-emitting film. The light-emitting film covers the top surface and outer periphery of the flip chip. The bottom surface of the flip chip is abutted against and connected to two spaced conductive sheet units. The flip chip includes two electrodes, one of which is electrically connected to one of the conductive sheet units. The edge of the conductive sheet unit extends along the outer direction of the flip chip and protrudes beyond the outer periphery of the flip chip.

[0007] As a preferred embodiment, the device includes a PCB board and a plurality of light-emitting devices, the light-emitting devices being fixed at intervals to the PCB board, and the conductive sheet unit being electrically connected to the PCB board.

[0008] As a preferred embodiment, the top surface of the conductive sheet unit is electrically connected to the electrode, the bottom surface of the conductive sheet unit is electrically connected to the PCB board, and the top surface and the bottom surface of the conductive sheet unit are planes arranged parallel to each other.

[0009] As a preferred embodiment, one of the two conductive sheet units is provided with an electrode marking.

[0010] As a preferred embodiment, the surface of the conductive sheet unit is coated with a brightening layer.

[0011] A manufacturing process for a small-pitch display screen includes the following steps:

[0012] A conductive sheet is provided, the conductive sheet including an insulating layer and a plurality of the conductive sheet units, with adjacent conductive sheet units fixed to the insulating layer at intervals;

[0013] Multiple flip chips are respectively fixed in the conductive sheet, and the two electrodes of the flip chip are electrically connected to two adjacent conductive sheet units through adhesive to form a light-emitting device unit. The outer periphery of the conductive sheet unit protrudes from the outer periphery of the flip chip.

[0014] A light-emitting film is provided, which is then laid on the top surface of the flip chip, and the light-emitting film is cured on the top surface of the flip chip and the outer periphery of the flip chip by a molding process;

[0015] Cut the light-emitting device unit along the outer periphery of the conductive sheet unit;

[0016] A PCB board is provided, and the light-emitting device unit is fixed to the PCB board by means of surface mounting or die bonding.

[0017] As a preferred embodiment, the light-emitting device unit is cut by wire cutting or laser cutting.

[0018] As a preferred embodiment, the conductive sheet includes an insulating layer and a conductive layer. Before the step of providing the conductive sheet, the conductive layer is fixed to the surface of the insulating layer. The conductive layer is formed into the conductive sheet unit by etching. Adjacent conductive sheet units are spaced apart.

[0019] As a preferred embodiment, one of the conductive sheet units in the light-emitting device unit is provided with an electrode mark, which is an electrode mark notch, and the electrode mark notch is formed simultaneously in the conductive layer etching step.

[0020] As a preferred embodiment, before providing the conductive sheet, the surface of the conductive layer is electroplated to form a brightening layer.

[0021] Compared with existing technologies, the present invention discloses a small-pitch display screen and its manufacturing process. The advantages are as follows: The two electrodes of the flip chip are respectively connected to two spaced-apart conductive sheet units. The edges of the conductive sheet units extend along the outer side of the flip chip and protrude from the outer periphery of the flip chip. By using these conductive sheet units and connecting them to the PCB board, the size of the two electrodes of the flip chip is expanded, facilitating the connection and installation of the flip chip electrodes to the PCB board. This reduces the difficulty of connecting and installing the flip chip electrodes to the PCB board, decreases reliance on equipment precision and the professional level of technicians, increases the contact area between the chip electrodes and the PCB board, and improves product yield. The chip's outer periphery is unobstructed by a support structure, allowing for a larger emission angle for the micro-light-emitting devices, increasing the emission angle from 120° to greater than 160°. The light-emitting film covers the top surface and outer periphery of the chip, improving the refractive index and reflectivity of the micro-light-emitting devices, resulting in more uniform light emission. Therefore, it is more conducive to ensuring the consistency of color points on the display screen. Attached Figure Description

[0022] Figure 1 This is a side view of the overall structure of an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the conductive sheet in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of a conductive sheet with a flip chip mounted on it, according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of the light-emitting device according to an embodiment of the present invention.

[0026] Figure 5 This is a side view of the overall structure of an embodiment of the present invention.

[0027] Figure 6 This is a top view of the overall structure of an embodiment of the present invention.

[0028] In the picture:

[0029] 10. Light-emitting devices; 11. PCB board;

[0030] 20. Flip chip; 21. Light-emitting film;

[0031] 30. Conductive sheet; 31. Conductive sheet unit; 32. Electrode marking; 33. Conductive layer; 34. Insulating layer; 35. Insulating gap; 36. Lower extension. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0034] In the description of this invention, it should be understood that the terms "connected," "linked," and "fixed," etc., used in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or a welded connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] like Figures 1 to 6 As shown in the preferred embodiment of the present invention, a small-pitch display screen includes a light-emitting device 10. The light-emitting device 10 includes a flip chip 20 and a light-emitting film 21. The light-emitting film 21 covers the top surface and the outer periphery of the flip chip 20. The bottom surface of the flip chip 20 is abutted against and connected to two spaced conductive sheet units 31. The flip chip 20 includes two electrodes, one of which is electrically connected to one conductive sheet unit 31. The edge of the conductive sheet unit 31 extends along the outer side of the flip chip 20 and protrudes from the outer periphery of the flip chip 20.

[0036] In the small-pitch display of the present invention, the two electrodes of the flip chip 20 are respectively connected to two spaced conductive sheet units 31. The edges of the conductive sheet units 31 extend along the outer direction of the flip chip 20 and protrude from the outer periphery of the flip chip 20. Through the arrangement of the conductive sheet units 31 and their connection to the PCB board 11, the size of the two electrodes of the flip chip 20 is expanded, facilitating the connection and installation of the electrodes of the flip chip 20 to the PCB board 11. This reduces the difficulty of connecting and installing the electrodes of the flip chip 20 to the PCB board 11, reduces reliance on equipment precision and the professional level of technicians, increases the contact area between the electrodes of the flip chip 20 and the PCB board 11, and improves the product yield. The conductive sheet units 31 of the present invention replace the existing brackets for fixing the flip chip 20. Without bracket obstruction on the outer periphery of the flip chip 20, the light emission angle of the micro-light-emitting device 10 is increased from 120° to greater than 160°. The light-emitting film 21 covers the top surface and outer periphery of the flip chip 20, improving the refractive index and reflectivity of the micro-light-emitting device 10, making the light emission more uniform, and thus making it easier to ensure the consistency of the color points of the display screen.

[0037] As a preferred option, such as Figure 4 As shown, the light-emitting film 21 includes titanium dioxide and silicone. The film is formed by mixing titanium dioxide and silicone. Titanium dioxide has good reflection and refraction effects, so that the light emitted by the light-emitting device 10 is more uniform after reflection and refraction.

[0038] Furthermore, such as Figure 5 As shown, the light-emitting device includes an insulating layer 34 and conductive sheet units 31. A lower extension 36 is formed by extending downwards from the inner side of the conductive sheet unit 31 within the same light-emitting device. The insulating layer 34 is located outside the lower extension 36, with its side surface connected to the lower extension 36. The top surface of the insulating layer 34 abuts against the conductive sheet unit 31, and two conductive sheet units 31 are spaced apart. Preferably, the bottom surface of the insulating layer 34 is flush with the bottom surface of the lower extension 36, which helps improve the flatness of the light-emitting device installation and enhances the uniformity of the light-emitting angle of the light-emitting device in the display screen.

[0039] Furthermore, such as Figure 1As shown, the display includes a PCB board 11 and multiple light-emitting devices 10. The light-emitting devices 10 are fixed to the PCB board 11 at intervals, and the conductive sheet unit 31 is electrically connected to the PCB board 11. Since each of the multiple light-emitting devices 10 is individually electrically connected to the PCB board 11 through the conductive sheet unit 31, the connection area between the conductive sheet unit 31 and the PCB board 11 is relatively large, increasing the operating space between the conductive sheet unit 31 and the PCB board 11. This is more conducive to the operation of small-pitch displays, reduces the difficulty of connecting the flip chip 20 to the PCB board 11, and improves the yield rate of small-pitch displays. At the same time, since the multiple light-emitting devices 10 are independent of each other, maintenance is easier, improving maintenance efficiency. In case of failure, there is no need to replace the entire display; only the damaged light-emitting device 10 needs to be replaced, reducing usage and after-sales costs.

[0040] Furthermore, such as Figure 1 As shown, the top surface of the conductive sheet unit 31 is electrically connected to the electrode, and the bottom surface of the conductive sheet unit 31 is electrically connected to the PCB board 11. The top and bottom surfaces of the conductive sheet unit 31 are parallel planes. The electrodes of the chip and the PCB board 11 are fixed together by solder paste to form a micro-sized light-emitting device 10. After the solder paste melts, the flip chip 20 cannot be mounted perpendicular to the PCB board 11, which makes it difficult to unify the light emission angle of the flip chip 20, resulting in a low product yield. Because the conductive sheet unit 31 increases the area of ​​connection between the electrodes of the flip chip 20 and the PCB board 11, the top surface of the conductive sheet unit 31 is connected to the electrodes by adhesive. The adhesive is located between the bottom surface of the flip chip 20 and the top surface of the conductive sheet unit 31. Since the top surface of the conductive sheet unit 31 is flat, the adhesive is easy to spread and flatten under the gravity of the flip chip 20. At the same time, the bottom surface of the conductive sheet unit 31 is bonded to the PCB board 11 by adhesive. Since the bottom surface of the conductive sheet unit 31 is flat, the adhesive is easy to spread and flatten. Since the top surface and the bottom surface of the conductive sheet unit 31 are set parallel to each other, the flip chip 20 is mounted perpendicular to the PCB board 11, improving the uniformity of the light emission angle of the micro light-emitting device 10.

[0041] Furthermore, such as Figure 4 As shown, one of the two conductive sheet units 31 is provided with an electrode mark 32 to facilitate identification of the positive and negative terminals of the flip chip 20 when connected to the PCB board 11.

[0042] As a preferred option, such as Figure 4 As shown, electrode mark 32 is a notch mark. The notch mark is easy to process and helps to improve the processing efficiency of the micro-light-emitting device 10.

[0043] Furthermore, the surface of the conductive sheet unit 31 is covered with a brightening layer. The brightening layer is treated with a brightening process, such as silver plating on the surface of the conductive sheet unit 31, to increase the surface reflectivity of the conductive sheet unit 31 and prevent the conductive sheet unit 31 from being oxidized, thereby extending the service life of the conductive sheet unit 31.

[0044] A manufacturing process for a small-pitch display screen includes the following steps:

[0045] like Figure 2 As shown, a conductive sheet 30 is provided. The conductive sheet 30 includes an insulating layer 34 and a plurality of conductive sheet units 31, with adjacent conductive sheet units 31 fixed to the insulating layer 34 at intervals.

[0046] like Figure 3 As shown, multiple flip chips 20 are fixed in conductive sheets 30 respectively. The two electrodes of the flip chip 20 are electrically connected to two adjacent conductive sheet units 31 through adhesive to form a light-emitting device unit. The outer periphery of the conductive sheet unit 31 protrudes from the outer periphery of the flip chip 20.

[0047] like Figure 3 As shown, a light-emitting film 21 is provided, which is laid on the top surface of the flip chip 20, and the light-emitting film 21 is cured on the top surface and the outer periphery of the flip chip 20 by a molding process.

[0048] like Figure 4 - Figure 5 As shown, the light-emitting device unit is cut along the outer periphery of the conductive sheet unit 31;

[0049] like Figure 6 As shown, a PCB board 11 is provided, and the light-emitting device unit is fixed to the PCB board 11 to form a small-pitch display screen.

[0050] The manufacturing process of the small-pitch display screen of the present invention involves fixing multiple flip chips 20 in a conductive sheet 30 containing multiple conductive sheet units 31, and covering the top surface of the flip chips 20 with a light-emitting film 21. Multiple flip chips 20 are then thermo-pressed together using a single light-emitting film 21. After the light-emitting film 21 is cured in each flip chip 20, each light-emitting device unit is segmented, enabling mass production of the light-emitting device units. The manufacturing process is simple, low-cost, and improves the production efficiency of the light-emitting device units. The outer periphery of the conductive sheet unit 31 protrudes from the outer periphery of the flip chip 20. Individual light-emitting device units are formed by cutting along the outer periphery of the conductive sheet unit 31 to increase the connection area between the light-emitting device unit and the PCB board 11. This ensures that the electrode size is comparable to the overall finished product size, guaranteeing a high yield rate while minimizing the size of the light-emitting device units, which is more conducive to small-pitch display screen operation. The final size of the light-emitting device unit is minimized to 0.4mm * 0.2mm * 0.15mm.

[0051] Furthermore, such as Figure 4 - Figure 5 As shown, the light-emitting device unit is cut using processes such as wire cutting and laser cutting, resulting in a smooth, burr-free outer periphery, high product precision, and high production efficiency.

[0052] Of course, the cutting of the light-emitting device unit can also be achieved in other ways, simply by cutting along the outer periphery of the conductive sheet unit 31.

[0053] Furthermore, such as Figure 3 As shown, the conductive sheet 30 includes an insulating layer 34 and a conductive layer 33. Before the step of providing the conductive sheet 30, the conductive layer 33 is fixed to the surface of the insulating layer 34. The conductive layer 33 is etched to form conductive sheet units 31, and adjacent conductive sheet units 31 are spaced apart.

[0054] It should be noted that the insulating layer 34 is made of insulating material, and an insulating gap 35 is formed in the insulating layer 34.

[0055] Furthermore, such as Figure 4 As shown, one of the two conductive sheets 30 in the light-emitting device unit is provided with an electrode mark 32, which is an electrode mark notch. The electrode mark notch is formed simultaneously during the etching of the conductive sheet unit 31. The simultaneous formation of the electrode mark notch during the conductive layer etching step simplifies the production process, improves the production efficiency of the light-emitting device unit, and enhances the identification of the positive and negative electrodes in the light-emitting device unit, facilitating the correct installation of the light-emitting device unit onto the PCB board 11 and improving the yield rate.

[0056] Furthermore, prior to providing the conductive sheet 30, a brightening layer is formed by electroplating the surface of the conductive layer 33. This brightening treatment increases the surface reflectivity and prevents oxidation of the conductive layer 33. The brightening layer is composed of a highly reflective material, such as silver. A silver brightening layer is formed by plating silver onto the surface of the conductive layer 33.

[0057] Preferably, the conductive layer 33 is copper foil, which has excellent conductivity, and the thickness of the conductive sheet 30 is set at 15-18 μm.

[0058] Furthermore, such as Figure 2As shown, the conductive sheet 30 includes multiple conductive strips and a connecting frame. The conductive strips are conductive layers 33, and the connecting frame is an insulating layer 34. The multiple conductive strips are connected by the connecting frame to form a whole. The conductive strips are laid flat, and insulating gaps 35 are formed between adjacent conductive strips. Multiple conductive sheet units 31 are formed along the extension direction of the conductive strips. Two adjacent conductive strips form a chip connection group. The conductive sheet units 31 in the same chip connection group are positioned correspondingly. The electrodes of the flip chip 20 are electrically connected to the corresponding conductive sheet units 31 in the chip connection group. The adjacent conductive strips are spaced apart, so that the two conductive strips are distributed at opposite ends of the flip chip 20. The conductive strips are etched to form conductive sheet units 31 to meet the installation requirements of the flip chip 20 electrodes, which facilitates mass production and improves production efficiency. Multiple flip chips 20 are fixed sequentially along the extension direction of the conductive strips, which facilitates mass cutting and improves production efficiency.

[0059] In summary, this invention provides a small-pitch display screen and its manufacturing process. The fabrication process of the light-emitting device 10 is simple, low-cost, and easy to mass-produce. When applied to a display screen, the addition of a conductive sheet unit 31 at the bottom makes product yield easier to control, reducing reliance on equipment precision and skilled operators. Simultaneously, the light-emitting device 10 can be miniaturized, for example, to 0.4mm * 0.2mm * 0.15mm, while ensuring that the electrode size is comparable to the overall finished product size. This ensures yield while miniaturizing the device, making it more suitable for small-pitch display screen applications. Furthermore, compared to traditional packaged devices, the light-emitting angle can be increased from 120° to greater than 160°, and the use of titanium dioxide with good refractive index and reflectivity as a cover layer results in more uniform light emission, making it more suitable for display screen applications.

[0060] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A small-pitch display screen, characterized in that: The device includes a light-emitting device comprising a flip chip and a light-emitting film. The light-emitting film covers the top surface and outer periphery of the flip chip. Two spaced-apart conductive sheet units are attached to the bottom surface of the flip chip. The flip chip includes two electrodes, one of which is electrically connected to one of the conductive sheet units. The edges of the conductive sheet units extend outward from the flip chip and protrude beyond the outer periphery of the flip chip. The inner side of the conductive sheet unit extends downward to form a lower extension. An insulating layer is provided on the outer side of the lower extension. The side surface of the insulating layer is connected to the lower extension, the top surface of which abuts against the conductive sheet unit, and the bottom surface of the insulating layer is flush with the bottom surface of the lower extension.

2. The small-pitch display screen according to claim 1, characterized in that: It includes a PCB board and a plurality of light-emitting devices, the light-emitting devices being fixed at intervals on the PCB board, the conductive sheet unit being electrically connected to the PCB board; adjacent light-emitting devices are connected through the insulating layer.

3. The small-pitch display screen according to claim 2, characterized in that: The top surface of the conductive sheet unit is electrically connected to the electrode, and the bottom surface of the conductive sheet unit is electrically connected to the PCB board. The top surface and the bottom surface of the conductive sheet unit are planes that are parallel to each other.

4. The small-pitch display screen according to claim 1, characterized in that: One of the two conductive sheet units is provided with an electrode marking.

5. The small-pitch display screen according to claim 1, characterized in that: The surface of the conductive sheet unit is covered with a brightening layer.

6. A manufacturing process for a small-pitch display screen, characterized in that: The method for producing the small-pitch display screen according to any one of claims 1-5 includes the following steps: A conductive sheet is provided, the conductive sheet including an insulating layer and a plurality of the conductive sheet units, with adjacent conductive sheet units fixed to the insulating layer at intervals; Multiple flip chips are respectively fixed in the conductive sheet. The two electrodes of the flip chip are electrically connected to two adjacent conductive sheet units through adhesive to form a light-emitting device unit. The outer periphery of the conductive sheet unit protrudes from the outer periphery of the flip chip. A light-emitting film is provided, which is then laid on the top surface of the flip chip, and the light-emitting film is cured on the top surface of the flip chip and the outer periphery of the flip chip by a molding process; Cut the light-emitting device unit along the outer periphery of the conductive sheet unit; A PCB board is provided, and the light-emitting device unit is fixed to the PCB board by means of surface mounting or die bonding.

7. The manufacturing process of the small-pitch display screen according to claim 6, characterized in that: The light-emitting device unit is cut using wire cutting or laser cutting processes.

8. The manufacturing process of the small-pitch display screen according to claim 6, characterized in that: The conductive sheet includes an insulating layer and a conductive layer. Before the step of providing the conductive sheet, the conductive layer is fixed to the surface of the insulating layer. The conductive layer is formed into the conductive sheet unit by etching. Adjacent conductive sheet units are spaced apart.

9. The manufacturing process of the small-pitch display screen according to claim 8, characterized in that: One of the conductive sheet units in the light-emitting device unit is provided with an electrode mark, which is an electrode mark notch, and the electrode mark notch is formed simultaneously in the conductive layer etching step.

10. The manufacturing process of the small-pitch display screen according to claim 8, characterized in that: Before providing the conductive sheet, the surface of the conductive layer is electroplated to form a brightening layer.

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