Double-sided transparent display panel and preparation method thereof

Abstract

The application relates to the technical field of display, in particular to a double-sided transparent display panel and a preparation method thereof, which comprises an LED device, a thin film transistor and a light-transmitting substrate, the LED device and the thin film transistor are arranged on the transparent substrate, the LED device and the thin film transistor are electrically connected through a metal lap joint line, the LED device, the thin film transistor and the metal lap joint line are transparently encapsulated on the light-transmitting substrate; the light-emitting surface of the LED device is directly attached on the light-transmitting substrate, and the electrode is arranged on the side away from the substrate, so that the shielding of the LED light-emitting by solder in traditional welding is avoided, the electrode size of the LED device and the width of the metal lap joint line are optimized, the area of the metal connection part is minimized, and the light shielding is further reduced; finally, the light emitted by the LED device can be more uniformly transmitted from both sides of the display panel, and the brightness uniformity of the double-sided display is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically to a double-sided transparent display panel and its preparation method. Background Technology

[0002] With the rapid development of display technology, LED displays, with their high brightness, high contrast, and long lifespan, are widely used in various display fields. Among current Micro-LED and Mini LED technologies, transparent display technology has attracted much attention, as it enables the display unit to be transparent, suitable for the special needs of double-sided displays. However, in existing technologies, transparent displays typically connect the LEDs to the driving circuitry via reflow soldering on metal pads. This method has the following problems:

[0003] Light blocking issue: Since solder is usually an opaque material (such as tin-based alloy), the solder position will block some of the light emitted by the LED device, resulting in uneven brightness on both sides of the display.

[0004] Reliability issues: During long-term use, solder may experience metal migration, which can affect the stability and lifespan of the device.

[0005] Manufacturing process limitations: Traditional soldering methods require a large amount of solder and have wide solder pads, which makes it difficult to meet the miniaturization and high light transmittance requirements of high-precision displays.

[0006] In summary, existing technologies in the field of transparent displays still face key bottlenecks such as light shielding and reliability issues, and there is an urgent need for an improved technical solution to address these problems in order to enhance the brightness uniformity and device stability of double-sided displays. Summary of the Invention

[0007] The present invention aims to solve the technical problems existing in the current transparent display structure, such as uneven brightness on both sides, large light-blocking area, and metal migration affecting reliability. The purpose is to provide a double-sided transparent display panel and its preparation method, which achieves the technical effects of reducing the light-blocking area, optimizing the brightness uniformity of the double-sided display, and improving the overall reliability of the device.

[0008] This invention is achieved through the following technical solution:

[0009] A double-sided transparent display panel includes: an LED device, a thin-film transistor, and a light-transmitting substrate. The LED device and the thin-film transistor are both disposed on the light-transmitting substrate. The LED device and the thin-film transistor are electrically connected by a metal bonding wire. The LED device, the thin-film transistor, and the metal bonding wire are transparently encapsulated on the light-transmitting substrate.

[0010] Specifically, the light-emitting surface of the LED device is attached to the light-transmitting substrate, the electrodes of the LED device are disposed on the side of the light-emitting surface away from the substrate, and the metal bonding wire connects the thin-film transistor and the electrodes of the LED device.

[0011] Optionally, the plurality of LED devices are arranged in an array, and the thin-film transistor is disposed on one side of each of the plurality of LED devices.

[0012] Optionally, the material of the metal bridging wire is one or more of TAT, MAM, Cu, and Ag.

[0013] Optionally, the metal overlay line is prepared by PVD-PH-ETCH, the electrode area of ​​the LED device is controlled between 0.5 square micrometers and 2 square micrometers, the electrode length of the LED device is controlled between 2 micrometers and 10 micrometers, the width is controlled between 2 micrometers and 8 micrometers, and the width of the metal overlay line is controlled between 3 micrometers and 10 micrometers.

[0014] The width of the metal contact line is not greater than the electrode width of the LED device.

[0015] A method for preparing a double-sided transparent display panel, comprising: preparing the double-sided transparent display panel as described above, the method comprising:

[0016] The light-emitting surface of the LED device is attached to a light-transmitting substrate, on which thin-film transistors are pre-installed.

[0017] Prepare metal bonding wires to connect the electrodes of the LED device and the thin-film transistor for electrical connection;

[0018] Transparent encapsulation of LED devices, thin-film transistors, and metal bonding wires.

[0019] Optionally, a method for preparing a metal bridging wire includes:

[0020] Deposit a metal layer using physical vapor deposition;

[0021] The metal layer is photolithographically processed to form the desired pattern of metal overlap lines;

[0022] The unmasked metal layer is removed by etching to obtain the metal overlap line.

[0023] If the metal layer has a TAT structure, then the bottom layer is a titanium layer, the middle layer is an aluminum layer, and the top layer is a titanium layer.

[0024] If the metal layer is a MAM structure, then the bottom layer is a molybdenum layer, the middle layer is an aluminum layer, and the top layer is a molybdenum layer.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] This invention provides a double-sided transparent display panel, including LED devices, thin-film transistors, and a light-transmitting substrate. Both the LED devices and thin-film transistors are disposed on the light-transmitting substrate and electrically connected via metal bonding wires. This invention avoids the blocking of LED light emission by solder in traditional soldering by directly attaching the light-emitting surface of the LED devices to the light-transmitting substrate and placing the electrodes on the side facing away from the substrate. By optimizing the electrode size of the LED devices and the width of the metal bonding wires, the area of ​​the metal connection portion is minimized, further reducing light shading. Ultimately, this allows the light emitted by the LED devices to pass through the display panel more uniformly from both sides, significantly improving the brightness uniformity of the double-sided display. Attached Figure Description

[0027] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0028] Figure 1 This is an isometric view of a double-sided transparent display panel according to the present invention.

[0029] Figure 2 This is a top view of a double-sided transparent display panel according to the present invention.

[0030] Reference numerals: 1-Transparent substrate, 2-Thin film transistor, 3-LED device, 4-Metal connection line, 5-Electrode. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., 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 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. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Micro-LED and Mini LED are important development directions in the field of display technology in recent years, and are widely used in high-end display devices due to their superior display performance. The main difference between the two lies in the size of the LED chip:

[0037] Micro-LED: The chip size is typically less than 100 micrometers, making it suitable for ultra-high resolution displays and high-density pixel arrangements.

[0038] Mini LED: Chip size is typically between 100 and 200 micrometers, making it suitable for local dimming backlight systems or large-size displays.

[0039] Micro / Mini LED displays achieve high brightness, low power consumption, and long lifespan through individually driven LED chips, and excel in color reproduction and dynamic contrast. Their small size and high density make them an ideal choice for future transparent display technologies.

[0040] Double-sided transparent display is a special display technology that allows content to be displayed on both sides of the display device while maintaining high light transmittance and brightness uniformity. Its core technical requirements include: ensuring that light can pass through the display device in both directions to achieve a transparent effect; reducing brightness differences between the two sides of the display unit to provide a consistent visual experience; and ensuring long-term operational stability to avoid performance degradation caused by environmental factors (such as temperature and humidity).

[0041] Existing transparent display technologies typically employ OLED (Organic Light Emitting Diode) or LCD (Liquid Crystal Display). While OLED technology boasts self-emissive properties and high contrast, it is susceptible to brightness decay and screen aging limitations in transparent displays. LCD technology, due to the presence of a backlight module, exhibits relatively low light transmittance in transparent displays, failing to meet the demands for high light transmittance.

[0042] Therefore, Micro / Mini LED technology, with its high brightness, high resolution, and reliability, provides ideal technical support for double-sided transparent displays.

[0043] In existing LED transparent display technology, to achieve double-sided transparent display, a reflow soldering method using metal pads and solder is typically employed to connect the LED device 3 to the driving circuit. A typical process flow for this method is as follows:

[0044] Metal pad design: Metal pads are placed on the transparent substrate. The pads are usually made of opaque tin-based alloys or other metal materials to achieve conductive connection.

[0045] Reflow soldering: By adding solder (such as solder paste) to the pads and fixing the LED device 3 onto the solder, the solder is then melted by heating, thus connecting the LED to the circuit.

[0046] Optical adjustment: After welding, the optical performance of the display unit is further adjusted to try to optimize the brightness of the double-sided display.

[0047] However, existing technologies have the following drawbacks:

[0048] Light blocking issue: Due to the opacity of the solder and pad materials, most of the light emitted by LED device 3 is blocked, especially the side closer to the soldering area, which has weaker brightness, resulting in uneven brightness on both sides of the display.

[0049] Metal migration: During long-term use, solder may migrate metals, resulting in unstable electrical connections or short circuits, which affects the reliability of the device.

[0050] Limited processing precision: Traditional reflow soldering has a large pad area, and it is difficult to precisely control the amount of solder used, which makes it difficult to meet the miniaturization and high precision requirements of transparent displays.

[0051] The process flow used in this invention is briefly described below:

[0052] Physical Vapor Deposition (PVD): This process involves vaporizing a metal material and depositing it onto a substrate surface to form a film. Compared to traditional bonding, PVD technology can achieve thinner and more uniform metal layers, helping to reduce light shading and improve conductivity.

[0053] Photolithography: Photolithography is a microfabrication technique that uses a photomask pattern to precisely transfer the shape of the metal bonding line 4 onto a substrate.

[0054] Etching: Etching is a process for removing excess metal material, and it is divided into dry etching (such as plasma etching) and wet etching (such as chemical etching). In this technical solution, the line width and shape of the metal overlap line 4 can be precisely controlled through the etching process.

[0055] Example 1

[0056] like Figure 1 and Figure 2 As shown, a double-sided transparent display panel is provided. Through a specific structural design and connection method, light shading is reduced and the brightness uniformity and reliability of the double-sided display are improved. The entire structure consists of LED devices 3, thin-film transistors 2 (TFTs), and a light-transmitting substrate 1. The double-sided transparent display function is achieved through optimized arrangement and transparent encapsulation technology.

[0057] The LED device 3 and the thin film transistor 2 are both disposed on the light-transmitting substrate 1. The LED device 3 and the thin film transistor 2 are electrically connected by a metal bonding wire 4. The LED device 3, the thin film transistor 2 and the metal bonding wire 4 are transparently encapsulated on the light-transmitting substrate.

[0058] The light-emitting surface of the LED device 3 is bonded to the light-transmitting substrate, ensuring that the LED light can be partially transmitted to the outside of the substrate, thereby achieving the effect of transparent display.

[0059] The electrode 5 of the LED device 3 is disposed on the side of the light-emitting surface away from the substrate and is used to connect the thin-film transistor 2 (TFT).

[0060] The metal bonding wire 4 connects the electrodes 5 of the thin-film transistor 2 and the LED device 3. The metal bonding wire 4 is designed to achieve low light shading and high conductivity.

[0061] Multiple LED devices 3 are arranged in an array to form an ordered display unit structure. Each of the multiple LED devices 3 has a thin-film transistor 2 on one side, so that each LED device 3 can be individually connected to the thin-film transistor 2 control unit to ensure precise driving of the display device.

[0062] In addition, by selecting appropriate materials and using advanced manufacturing processes, combined with the optimization of the geometry of electrode 5 and metal connection line 4, light shading can be minimized, conductivity improved, and structural reliability enhanced.

[0063] The metal bonding wire 4 is made of one or more of the following: TAT (titanium-aluminum-titanium), MAM (molybdenum-aluminum-molybdenum), Cu (copper), or Ag (silver). TAT and MAM are multilayer metal structures that combine high electrical conductivity with a low coefficient of thermal expansion. Cu and Ag both have good electrical conductivity, but Cu has lower conductivity than Ag and is less expensive; Ag has better conductivity than Cu and is more expensive.

[0064] The metal bonding line 4 is fabricated using PVD-PH-ETCH. The area of ​​the electrode 5 of the LED device 3 is controlled between 0.5 square micrometers and 2 square micrometers, the length of the electrode 5 is controlled between 2 micrometers and 10 micrometers, and the width is controlled between 2 micrometers and 8 micrometers. The width of the metal bonding line 4 is controlled between 3 micrometers and 10 micrometers. These dimensions are only one example and can be adjusted according to actual conditions. The overall requirement is to minimize the LED electrode 5 and the line width of the electrode 5, thereby minimizing the light-blocking area on one side of the LED, which corresponds to maximizing the LED light output. Ultimately, the difference in brightness between the two sides of the transparent display is minimized, and the brightness of the two sides is maximized.

[0065] The width of the metal connection line 4 is no greater than the width of the electrode 5 of the LED device 3. By reasonably controlling the width of the metal connection line 4 and the area of ​​the electrode 5, light shading is significantly reduced, and uniformity of brightness on both sides of the display unit is achieved.

[0066] Example 2

[0067] This embodiment provides a method for preparing a double-sided transparent display panel, including:

[0068] Select a suitable light-transmitting substrate 1, such as a glass substrate or a transparent flexible substrate, to ensure that the light-transmitting substrate 1 has good light transmittance, flatness and heat resistance, and then fabricate a thin film transistor array 2 on the light-transmitting substrate 1.

[0069] The light-emitting surface of the LED device 3 is attached to the light-transmitting substrate 1 with the light-emitting surface of the LED device 3 facing down. That is, the light-emitting surface of the LED device 3 is in direct contact with the light-transmitting substrate 1, and the light emitted by the LED device 3 can be directly emitted from the light-transmitting substrate 1.

[0070] Prepare a metal bonding wire 4, and make the metal bonding wire 4 electrically connect the electrode 5 of the LED device 3 and the thin film transistor 2.

[0071] The LED device 3, thin film transistor 2 and metal bonding wire 4 are transparently encapsulated using transparent encapsulating adhesive (such as epoxy resin, silicone resin, etc.) or other transparent encapsulating materials to prevent the LED device 3, thin film transistor 2, metal bonding wire 4 and transparent substrate 1 from being corroded by environmental factors (such as moisture, dust, oxygen, etc.) while maintaining the transparency of the display panel.

[0072] In addition, this embodiment also provides a method for fabricating a metal bridging line, which uses physical vapor deposition (PVD), photolithography and etching techniques to form a metal bridging line 4 with high precision and low light-shielding characteristics. The fabrication method includes:

[0073] Metal layers are deposited using physical vapor deposition (PVD). PVD involves heating and evaporating metal materials before depositing them onto the substrate surface to form a uniform thin film. The structure of the metal layer can be either TAT (titanium-as-aluminum) or MAM (metal-as-molecular-weighted) layers, or pure Cu or pure Ag, to meet the needs of different applications. If the metal layer has a TAT structure, the bottom layer is a titanium layer, the middle layer is an aluminum layer, and the top layer is a titanium layer. If the metal layer has a MAM structure, the bottom layer is a molybdenum layer, the middle layer is an aluminum layer, and the top layer is a molybdenum layer.

[0074] The metal layer is photolithographically processed to form the desired metal overlap line pattern 4; photoresist is used to cover the surface of the metal layer, and the pattern is transferred by ultraviolet light irradiation. After exposure and development steps, the desired overlap line pattern mask is formed on the surface of the metal layer.

[0075] The unmasked metal layer is removed using an etching process to obtain the metal overlap line 4. Etching processes include dry etching and wet etching. Dry etching (such as plasma etching) removes the metal by bombarding the unmasked area with plasma. Wet etching (such as chemical etching) dissolves the unmasked metal using a specific chemical solution.

[0076] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0077] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A double-sided transparent display panel, characterized in that, include: The LED device (3), the thin film transistor (2) and the light-transmitting substrate (1) are disposed on the light-transmitting substrate (1). The LED device (3) and the thin film transistor (2) are electrically connected by a metal bonding wire (4). The LED device (3), the thin film transistor (2) and the metal bonding wire (4) are transparently encapsulated on the light-transmitting substrate.

2. A double-sided transparent display panel according to claim 1, characterized in that, The light-emitting surface of the LED device (3) is attached to the light-transmitting substrate, and the electrode (5) of the LED device (3) is disposed on the side of the light-emitting surface away from the substrate. The metal bonding wire (4) connects the thin film transistor (2) and the electrode (5) of the LED device (3).

3. A double-sided transparent display panel according to claim 2, characterized in that, The multiple LED devices (3) are arranged in an array, and the thin film transistor (2) is disposed on one side of each of the multiple LED devices (3).

4. A double-sided transparent display panel according to claim 1, characterized in that, The material of the metal bridging wire (4) is one or more of TAT, MAM, Cu, and Ag.

5. A double-sided transparent display panel according to claim 2, characterized in that, The area of ​​the electrode (5) of the LED device (3) is controlled between 0.5 square micrometers and 2 square micrometers, the length of the electrode (5) of the LED device (3) is controlled between 2 micrometers and 10 micrometers, the width is controlled between 2 micrometers and 8 micrometers, and the width of the metal overlay wire (4) is controlled between 3 micrometers and 10 micrometers.

6. A double-sided transparent display panel according to claim 2, characterized in that, The width of the metal bonding wire (4) is not greater than the width of the electrode (5) of the LED device (3).

7. A method for preparing a double-sided transparent display panel, characterized in that, The method for preparing a double-sided transparent display panel as described in any one of claims 1-6 includes: The light-emitting surface of the LED device (3) is attached to the light-transmitting substrate (1), and a thin-film transistor (2) is pre-installed on the light-transmitting substrate (1); Prepare a metal bonding wire (4) to electrically connect the electrode (5) of the LED device (3) and the thin film transistor (2); The LED device (3), thin film transistor (2) and metal bonding wire (4) are transparently packaged.

8. The method for preparing a double-sided transparent display panel according to claim 7, characterized in that, The methods for preparing metal bridging wires (4) include: Deposit a metal layer using physical vapor deposition; The metal layer is photolithographically processed to form the pattern of the required metal overlap line (4); The unmasked metal layer was removed by etching to obtain the metal overlap line (4).

9. The method for fabricating an electrode (5) trace according to claim 8, characterized in that, If the metal layer has a TAT structure, then the bottom layer is a titanium layer, the middle layer is an aluminum layer, and the top layer is a titanium layer.

10. The method for fabricating an electrode (5) trace according to claim 8, characterized in that, If the metal layer is a MAM structure, then the bottom layer is a molybdenum layer, the middle layer is an aluminum layer, and the top layer is a molybdenum layer.

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