Display panel and method of manufacturing the same

Abstract

A display panel includes a drive substrate, a plurality of solder pads, a reflective layer, and a plurality of light-emitting units. The drive substrate includes a plurality of traces of a drive circuit for the display panel. The plurality of solder pads are disposed on the drive substrate and electrically connected to the plurality of traces of the drive circuit in the drive substrate. Each pair of solder pads is disposed in pairs. Each solder pad comprises a frustum. The reflective layer is disposed between two adjacent pairs of solder pads. The reflective layer is made of a photocurable reflective ink. Each light-emitting unit is electrically connected to a pair of solder pads.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a display panel with a high-reflectivity bevel pad. Background Art

[0002] With the advancement of display technology, various types of display panels have emerged. Compared to liquid crystal (LC) and organic light-emitting diode (OLED) display technologies, mini-light-emitting diode (mini-LED) display technology offers advantages such as superior response speed, display color gamut, contrast, resolution, and energy efficiency. Furthermore, mini-LED display technology can achieve precise dimming across a large number of display zones. Therefore, its promising development prospects have made it a hotspot for major display panel manufacturers.

[0003] In display panels that utilize the mini LED display technology, in order to improve brightness and light extraction efficiency, and reduce energy consumption, the prior art applies a layer of reflective ink to the surface of the display panel's driver substrate, so that the light emitted by the mini LEDs in the display panel is reflected as much as possible. The reflectivity of the display panel can be adjusted by adjusting the coating thickness of the reflective ink and the accuracy of the window opening. Currently, the most common method for manufacturing the reflective ink is to apply the reflective ink to the display panel's driver substrate via inkjet printing or screen printing, and then cure the reflective ink through exposure and development, and open windows to expose multiple pads for bonding the mini LEDs.

[0004] Please refer to Figure 1 , which is a partial structural diagram of a display panel in the prior art. The display panel includes a driver substrate 100', multiple solder pads 200', reflective ink 300', and multiple mini LEDs 400'. A pair of solder pads 200' electrically connects a mini LED 400' and multiple traces 110' in the driver substrate 100'. The reflective ink 300' is located between two adjacent pairs of solder pads 200' to reflect the light emitted by the multiple mini LEDs 400'.

[0005] In order to maximize the reflectivity of the display panel, the prior art designs the coating thickness of the reflective ink to be around 60 microns. However, since the reflective ink 300' is a light-curing material, the reflective ink 300' near the surface can be fully cured due to sufficient light exposure, but the reflective ink 300' near the bottom layer cannot be fully cured due to insufficient light exposure. The incompletely cured reflective ink 300' will be washed away by the developer in the subsequent process, thus forming the following Figure 1 According to simulation experiments and calculations by the inventors, the defects of the undercut shapes UC of the reflective ink 300' will cause the reflectivity of the display panel to drop by 15% to 20%, seriously reducing the display effect of the display panel.

[0006] The display panel in the prior art has a technical problem that the reflective ink cannot be fully cured. Therefore, a display panel with a high-reflectivity bevel pad is needed to solve the above technical problem. Summary of the Invention

[0007] The present invention provides a display panel having high-reflectivity beveled pads. The display panel includes a drive substrate, a plurality of pads, a reflective layer, and a plurality of light-emitting units. The drive substrate includes a plurality of traces of a drive circuit for the display panel. The plurality of pads are disposed on the drive substrate and electrically connected to the plurality of traces of the drive circuit in the drive substrate. Every two pads are disposed in pairs. Each pad comprises a frustum. The reflective layer is disposed between two adjacent pairs of pads. The reflective layer is made of a light-curable reflective ink. Each light-emitting unit is electrically connected to a pair of pads.

[0008] In one embodiment, the angle between at least one side surface and the bottom surface of the frustum of each pad is in a range of 40 degrees to 50 degrees.

[0009] In one embodiment, each of the pads is a truncated quadrangular pyramid or a truncated cone.

[0010] In one embodiment, the material of the plurality of pads includes copper, aluminum, silver, cobalt, palladium, iron, cadmium, nickel, and combinations thereof.

[0011] In one embodiment, the height of each of the pads ranges from 8 microns to 10 microns.

[0012] In this embodiment, the thickness of the reflective layer ranges from 55 micrometers to 60 micrometers.

[0013] The present invention also provides a method for manufacturing a display panel. The method for manufacturing a display panel comprises the following steps:

[0014] forming a driving substrate, wherein the driving substrate includes a plurality of traces of a driving circuit of the display panel;

[0015] forming a plurality of pads on the driving substrate, the plurality of pads being electrically connected to the plurality of traces of the driving circuit in the driving substrate, wherein every two pads are arranged in pairs, and each pad is formed into a frustum;

[0016] forming a reflective layer on the driving substrate, wherein the reflective layer is formed between two adjacent pairs of the pads, and a material of the reflective layer includes a light-curable reflective ink; and

[0017] The light emitting unit is electrically connected to each pair of the pads.

[0018] In one embodiment, the step of forming a plurality of pads on the driving substrate further includes the following steps:

[0019] forming an electroplating seed layer on the surface of the driving substrate;

[0020] forming a photoresist on the electroplating seed layer;

[0021] patterning the photoresist to form a frustum-shaped cavity in a region where each pad is to be formed;

[0022] electroplating the photoresist and the electroplating seed layer to form the pads filling the cavities of the photoresist;

[0023] removing the photoresist; and

[0024] The plurality of pads and the electroplating seed layer are etched to remove the electroplating seed layer outside the region where the plurality of pads are formed.

[0025] In this embodiment, the depth of the cavity is greater than or equal to the height of each of the pads, and the difference between the depth of the cavity and the height of each of the pads is in a range of 0 micrometers to 5 micrometers.

[0026] In this embodiment, the thickness of the photoresist ranges from 10 microns to 12 microns.

[0027] The present invention provides a display panel and a manufacturing method thereof. The display panel includes the drive substrate, the plurality of solder pads, the reflective layer, and the plurality of light-emitting units. The drive substrate includes a plurality of traces of the drive circuit of the display panel. The plurality of solder pads are arranged on the drive substrate and electrically connected to the plurality of traces of the drive circuit in the drive substrate. Every two solder pads are arranged in pairs. Each solder pad includes the frustum. The reflective layer is arranged between two adjacent pairs of solder pads. The material of the reflective layer includes the photocurable reflective ink. Each light-emitting unit is electrically connected to a pair of solder pads. Since each solder pad includes the frustum, the present invention can utilize the plurality of solder pads with high-reflectivity inclined surfaces to solve the technical problem that the prior art cannot fully cure the photocurable reflective ink of the reflective layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. 1 is a schematic diagram of a partial structure of a display panel in the prior art.

[0029] Figure 2 FIG. 4 is a schematic diagram of a partial structure of a display panel of the present invention.

[0030] Figure 3 It is a three-dimensional schematic diagram of the solder pad of the display panel of the present invention.

[0031] Figure 4 Another stereoscopic schematic diagram of the solder pad of the display panel of the present invention.

[0032] Figures 5 to 12 It is a structural schematic diagram of the manufacturing process of the display panel of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above and other objects, features and advantages of the present invention more clearly understood, preferred embodiments of the present invention will be specifically described below in detail with reference to the accompanying drawings.

[0034] Please refer to Figure 2, which is a partial structural diagram of the display panel of the present invention. The display panel includes a driving substrate 100, a plurality of pads 200, and a plurality of light-emitting units 400. The driving substrate 100 includes a plurality of traces 110 of the driving circuit of the display panel. The plurality of pads 200 are arranged on the driving substrate 100 and are electrically connected to the plurality of traces 110 of the driving circuit in the driving substrate 100. The plurality of pads 200 serve as binding pads for binding the light-emitting units 400, and every two of the pads 200 are arranged in pairs. The light-emitting units 400 are electrically connected to a pair of the pads 200, that is, each pair of the pads 200 includes an anode and a cathode to electrically connect the plurality of traces 110 of the driving substrate 100.

[0035] In order to improve the brightness and light extraction efficiency of the display panel and reduce the energy consumption of the display panel, the present invention provides a reflective layer 300 on the driving substrate 100 of the display panel so that the light emitted by the light-emitting unit 400 is reflected out of the display panel as much as possible. In one embodiment, the reflective layer 300 is provided between two adjacent pairs of the pads 200, that is, surrounding the area where the light-emitting element is predetermined to be bound. The material of the reflective layer 300 includes a reflective ink with a main color of white, preferably, includes a light-curing reflective ink. Through the inventor's simulation test, when its thickness ranges from 55 microns to 60 microns, the reflectivity can reach more than 92.5%.

[0036] To ensure that the photocurable reflective ink of the reflective layer 300 is fully exposed to light during the exposure process, the present invention configures each pad 200 to have a frustum. The frustum is formed by truncating the top of a conventional cone, and its cross section is parallel to the base 220 of the cone. The frustum is also known as a parallelepiped, a frustum, or a mesa.

[0037] Because at least one side surface 230 of each of the solder pads 200 of the present invention is configured as a sloped surface, during the exposure process of the light-curable reflective ink on the reflective layer 300, the curing light is reflected to the area of ​​the reflective layer 300 near the bottom layer. Thus, the reflective layer 300 near the surface can be fully cured due to sufficient exposure to light, and the reflective layer 300 near the bottom layer can also be fully cured due to sufficient exposure to light reflected from the multiple solder pads 200.

[0038] Please refer to Figure 3, which is a three-dimensional schematic diagram of one of the pads 200 of the display panel of the present invention. In this embodiment, each of the pads 200 is a truncated quadrangular pyramid, preferably, a truncated regular quadrangular pyramid. Each of the pads 200 includes a top surface 210, a bottom surface 220, and four side surfaces 230. In each of the pads 200, the top surface 210 is parallel to the bottom surface 220, and the four side surfaces 230 connect the top surface 210 and the bottom surface 220. As shown in the figure, the present invention configures one of the side surfaces 230 of each of the pads 200 to have an angle θ with the bottom surface 220 in the range of 40 degrees to 50 degrees, preferably 45 degrees.

[0039] Please refer to Figure 4 , which is another stereoscopic schematic diagram of one of the pads 200 of the display panel of the present invention. In this embodiment, each of the pads 200 can also be a truncated cone, preferably, a truncated right cone. Each of the pads 200 includes a top surface 210, a bottom surface 220, and a side surface 230. In each of the pads 200, the top surface 210 is parallel to the bottom surface 220, and the side surface 230 connects the top surface 210 and the bottom surface 220. As shown in the figure, the present invention configures the side surface 230 of each of the pads 200 to form an angle θ with the bottom surface 220 in the range of 40 degrees to 50 degrees, preferably 45 degrees.

[0040] Compared to Figure 3 The soldering pad 200 in the shape of a truncated quadrangular pyramid or a truncated circular cone can more evenly reflect the curing light to the reflective layer 300 close to the bottom layer, so that the light-curing reflective ink in the reflective layer 300 is cured more completely.

[0041] In one embodiment, to reflect the curing light as closely as possible to the reflective layer 300 near the bottom layer, allowing the light-curable reflective ink on the reflective layer 300 to fully cure, the solder pads 200 are constructed from a highly reflective metal. Preferably, the solder pads 200 are constructed from copper, aluminum, silver, cobalt, palladium, iron, cadmium, nickel, and combinations thereof. Furthermore, the solder pads 200 are highly conductive, enabling them to serve as bonding pads for the light-emitting units 400, ensuring a stable current supply to the light-emitting units 400.

[0042] It should be noted that the inventors' simulations have shown that when the thickness of the reflective layer 300 is set between 55 and 60 microns, the reflective layer 300 may exhibit an undercut defect approximately 10 microns in height after undergoing a conventional patterning process. Therefore, the present invention configures at least one side surface 230 of each pad 200 to have an angle θ between 40 and 50 degrees with the bottom surface 220, and also configures the height of each pad 200 to be between 8 and 10 microns.

[0043] Thanks to the structural design of the multiple solder pads 200 of the present invention, the photocurable reflective ink of the reflective layer 300 can be cured integrally after the patterning process, thereby avoiding the undercut defects that occur in the reflective layer of conventional display panels due to incomplete curing. This enables the reflective layer 300 of the display panel of the present invention to achieve a reflectivity exceeding the theoretical value, namely, a reflectivity of the reflective layer 300 exceeding 92.5%, thereby enhancing the display quality of the display panel and reducing its energy consumption.

[0044] The present invention also provides a method for manufacturing a display panel. The method for manufacturing a display panel includes the following steps S1 to S4. Figures 5 to 12 , which is a structural schematic diagram of the manufacturing process of the display panel of the present invention.

[0045] S1. Form the driving substrate 100. The driving substrate 100 includes the plurality of traces 110 of the driving circuit of the display panel.

[0046] S2. Form the plurality of pads 200 on the driving substrate 100. The plurality of pads 200 are electrically connected to the plurality of traces 110 of the driving substrate. To form the plurality of pads 200, this step further includes the following steps S21 to S26.

[0047] S21. Forming an electroplating seed layer 500 on the surface of the driving substrate 100. Figure 5 As shown, in order to form the plurality of metal pads 200 on the surface of the non-metallic driving substrate 100, a metal film of the electroplating seed layer 500 must first be formed. Preferably, the thickness of the electroplating seed layer 500 can be 0.6 microns.

[0048] In this step, in order to make the multiple pads 200 to be formed subsequently homogeneous with the electroplating seed layer 500, the electroplating seed layer 500 can be made of the same material as the multiple pads 200, such as copper, aluminum, silver, cobalt, palladium, iron, cadmium, nickel, and combinations thereof.

[0049] S22. Form a photoresist 600 on the electroplating seed layer 500. Figure 6 As shown, the present invention then forms the photoresist 600 with a thickness ranging from 10 microns to 12 microns on the electroplating seed layer 500. Since the predetermined height range of the plurality of pads 200 is between 8 microns and 10 microns, the predetermined thickness range of the photoresist 600 of the present invention is configured to be greater than or equal to the predetermined height range of the plurality of pads 200.

[0050] S23. Pattern the photoresist 600 to form a frustum-shaped cavity 610 in the predetermined area of ​​each pad 200. Figure 7 As shown, through patterning processes such as mask exposure, development, and rinsing, the photoresist 600 is opened to form a plurality of truncated pyramidal cavities 610, thereby providing spaces for the subsequent formation of the plurality of bonding pads 200. In one embodiment, the depth of the cavities 610 is greater than or equal to the predetermined height of each bonding pad 200, and the difference between the depth of the cavities 610 and the predetermined height of each bonding pad is in a range of 0 microns to 5 microns.

[0051] It should be noted that the material of the photoresist 600 of the present invention includes a negative photoresist 600. Preferably, the negative photoresist 600 can be selected from commercially available models such as Merck CPT-100. Due to the characteristics of the negative photoresist 600, after the photoresist 600 is patterned, the following will be formed: Figure 7 The shape of the undercut structure, such as the bevel angle, can be adjusted by adjusting the exposure level, development time, or baking time of the photoresist 600. In this way, a plurality of predetermined frustum-shaped cavities 610 can be formed according to actual implementation needs.

[0052] S24. Electroplating the photoresist 600 and the electroplating seed layer 500 to form the pad 200 filling the cavity 610 of the photoresist 600. Figure 8 As shown, after the plurality of cavities 610 are opened in the photoresist 600, the materials of the plurality of pads 200, such as copper, aluminum, silver, cobalt, palladium, iron, cadmium, nickel, and combinations thereof, can be filled into the cavities 610 of the plurality of frustums under the guidance of the electroplating seed layer 500 through an electroplating process such as wet electroplating to form each of the pads 200 of the frustum.

[0053] S25. Remove the photoresist 600. Figure 9As shown, after the plurality of pads 200 are formed in the plurality of cavities 610 of the photoresist 600 , the photoresist 600 can be stripped from the electroplating seed layer 500 and the plurality of pads 200 .

[0054] S24. Etching the plurality of pads 200 and the electroplating seed layer 500 to remove the electroplating seed layer 500 outside the region where the plurality of pads 200 are formed. Figure 10 As shown, since step S21 first forms a whole layer of the electroplating seed layer 500, in this case, the multiple traces 110 of the driving substrate 100 are all electrically connected to the electroplating seed layer 500. In order to insulate each of the pads 200 from each other and electrically connect each of the multiple traces 110 of the driving circuit in the driving substrate 100, the electroplating seed layer 500 outside the area where the multiple pads 200 are formed must be removed.

[0055] In this step, the electroplating seed layer 500 can be removed outside the region where the plurality of pads 200 are formed by etching the entire surface of the plurality of pads 200 and the electroplating seed layer 500. Since the thickness of the electroplating seed layer 500 is approximately 0.6 microns, only a thin surface of the plurality of pads 200 needs to be sacrificed to achieve insulation between the pads 200.

[0056] S3. Form a reflective layer 300 on the driving substrate 100. Figure 11 As shown, after step S2 is completed, the reflective layer 300 is formed between two adjacent pairs of pads 200. The light-curable reflective ink of the reflective layer 300 is applied to the drive substrate 100 by inkjet printing or screen printing. The light-curable reflective ink of the reflective layer 300 is then completely cured through a pre-bake process, an exposure process, a development process, and a main bake process. In this step, the exposure process can preferably be a laser direct imaging (LDI) process.

[0057] like Figure 11 As shown, when the light-curable reflective ink on the reflective layer 300 is exposed, because at least one side surface 230 of each of the pads 200 is configured as a slope, the light-curable reflective ink on the reflective layer 300 is able to reflect the curing light to the area of ​​the reflective layer 300 near the bottom layer during the exposure process. As a result, the reflective layer 300 near the surface can be fully cured due to sufficient light exposure, and the reflective layer 300 near the bottom layer can also be fully cured due to sufficient light reflected from the multiple pads 200.

[0058] S4. Electrically connect one of the light emitting units 400 to each pair of the pads 200. Figure 12 As shown, after step S3 is completed, the plurality of light emitting units 400 can be electrically connected to the plurality of pads 200. In this step, the plurality of light emitting units 400 are bonded to a pair of pads 200 by a mass reflow bonding process.

[0059] The present invention provides a display panel and a manufacturing method thereof. The display panel includes a drive substrate 100, a plurality of solder pads 200, a reflective layer 300, and a plurality of light-emitting units 400. The drive substrate 100 includes a plurality of traces 110 of the display panel's drive circuit. The plurality of solder pads 200 are disposed on the drive substrate 100 and electrically connected to the plurality of traces 110 of the drive circuit in the drive substrate 100. Every two solder pads 200 are disposed in pairs. Each solder pad 200 includes a frustum. The reflective layer 300 is disposed between two adjacent pairs of solder pads 200. The material of the reflective layer 300 includes the photocurable reflective ink. Each light-emitting unit 400 is electrically connected to a pair of solder pads 200. Because each solder pad 200 includes a frustum, the present invention can utilize the plurality of solder pads 200 having a high-reflectivity inclined surface to solve the technical problem of the prior art that the photocurable reflective ink in the reflective layer cannot be fully cured.

[0060] The above are only preferred embodiments of the present invention. It should be pointed out that those skilled in the art may make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A display panel, characterized in that: include: a driving substrate, comprising a plurality of wirings of a driving circuit of the display panel; a plurality of pads disposed on the driving substrate and electrically connected to the plurality of traces of the driving circuit in the driving substrate, wherein every two pads are disposed in pairs, and each pad comprises a frustum; a reflective layer disposed between two adjacent pairs of the pads, wherein the reflective layer is made of a light-curable reflective ink; and a plurality of light-emitting units, each of the light-emitting units being electrically connected to a pair of the pads; The sidewall of the pad is arranged opposite to the lower portion of the reflective layer, and the pad is configured to reflect light to the lower portion of the reflective layer when exposed to light.

2. The display panel according to claim 1, wherein The angle between at least one side surface and the bottom surface of the frustum of each pad is in a range of 40 degrees to 50 degrees.

3. The display panel according to claim 1, wherein Each of the pads is a truncated quadrangular pyramid or a truncated cone.

4. The display panel according to claim 1, wherein: Materials of the plurality of pads include copper, aluminum, silver, cobalt, palladium, iron, cadmium, nickel, and combinations thereof.

5. The display panel according to claim 1, wherein The height of each pad is between 8 microns and 10 microns.

6. The display panel according to claim 5, wherein: The thickness of the reflective layer ranges from 55 microns to 60 microns.

7. A method for manufacturing a display panel, characterized in that: A display panel according to any one of claims 1 to 6 is prepared, wherein the method for manufacturing the display panel comprises the following steps: forming a driving substrate, wherein the driving substrate includes a plurality of traces of a driving circuit of the display panel; forming a plurality of pads on the driving substrate, the plurality of pads being electrically connected to the plurality of traces of the driving circuit in the driving substrate, wherein every two pads are arranged in pairs, and each pad is formed into a frustum; forming a reflective layer on the driving substrate, wherein the reflective layer is formed between two adjacent pairs of the pads, and a material of the reflective layer includes a light-curable reflective ink; and The light emitting unit is electrically connected to each pair of the pads.

8. The method for manufacturing a display panel according to claim 7, wherein: The step of forming a plurality of pads on the driving substrate further includes the following steps: forming an electroplating seed layer on the surface of the driving substrate; forming a photoresist on the electroplating seed layer; patterning the photoresist to form a frustum-shaped cavity in a region where each pad is to be formed; electroplating the photoresist and the electroplating seed layer to form the pads filling the cavities of the photoresist; removing the photoresist; and The plurality of pads and the electroplating seed layer are etched to remove the electroplating seed layer outside the region where the plurality of pads are formed.

9. The method for manufacturing a display panel according to claim 8, wherein: The depth of the cavity is greater than or equal to the height of each of the pads, and the difference between the depth of the cavity and the height of each of the pads is in a range of 0 micrometers to 5 micrometers.

10. The method for manufacturing a display panel according to claim 8, wherein: The thickness of the photoresist ranges from 10 microns to 12 microns.

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