A Mini-LED display screen

Abstract

The present invention relates to a Mini-LED display screen, comprising a glass substrate, a driving circuit composed of a copper film is provided on the first surface of the glass substrate, a plurality of pairs of pads forming an array are provided on the driving circuit, and an LED is welded on each pair of pads, characterized in that each of the pads comprises a copper bottom layer and a thickened metal layer arranged on the copper bottom layer, the copper bottom layer is composed of the copper film, the thickness of the copper bottom layer is at least 1 μm, and the thickness of the thickened metal layer is greater than or equal to the thickness of the copper bottom layer. This Mini-LED display screen can not only make the pads stronger, reduce the damage to the driving circuit caused by the thermal expansion and contraction of the LED, but also disperse the shear strain and stress caused by the thermal expansion and contraction of the LED in the vertical direction, thereby avoiding the occurrence of failures caused by the breakage of the driving circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of display screens, and in particular to a Mini-LED display screen. Background Art

[0002] The Mini-LED display is a display that uses a large number of tiny LEDs (LEDs with a size of 50 to 300 μm) directly as pixels on the display driver board.

[0003] like Figure 1-Figure 2 As shown, the existing Mini-LED display screen generally uses a flat glass substrate 01 as a driving board, and the driving circuit on the driving board is generally made of a plated copper film 020 (thickness not less than 1μm). Based on the flatness of the glass substrate 01, the accuracy of its driving circuit is higher than that of an ordinary printed circuit board, so that the pixel density of the display screen can be improved, thereby achieving a higher resolution display. However, due to the high hardness of the glass substrate 01, when the copper film 020 is set on the glass substrate 01, the contact interface between the copper film 020 and the glass substrate 01 is prone to peeling due to excessive accumulated stress. This Mini-LED display screen generally uses an LED04 with a flip-chip COB structure. The two pins at the bottom of the LED04 are generally welded to the pads 030 at the ends of the two copper wires 03. During the welding process, the LED04 will experience a significant cooling process, and its thermal expansion and contraction (generally difficult to be consistent with the substrate) will form strain at the ends of the two copper wires 03. The stress generated is likely to cause the pads 030 at the ends of the copper wires 03 to peel off from the glass substrate 01, which may eventually cause the driving circuit to break and cause a failure.

[0004] In addition, the prior art also uses a method of covering the LED of the Mini-LED display with a layer of reinforcing glue layer to solve the above-mentioned problem. However, since the above-mentioned problem generally occurs in the cooling process of LED welding, the method of using a glue layer to reinforce it afterwards still cannot fundamentally solve the problem. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a Mini-LED display screen, which can not only make the solder pad stronger and reduce the damage to the driving circuit caused by the thermal expansion and contraction of the LED, but also disperse the shear strain and stress caused by the thermal expansion and contraction of the LED in the vertical direction, thereby avoiding the occurrence of failures caused by the breakage of the driving circuit. The technical solution adopted is as follows:

[0006] A Mini-LED display screen comprises a glass substrate, a driving circuit composed of a copper film is provided on the first surface of the glass substrate, a plurality of pairs of pads forming an array are provided on the driving circuit, an LED is welded to each pair of pads, and the feature is that each of the pads comprises a copper bottom layer and a thickened metal layer arranged on the copper bottom layer, the copper bottom layer is composed of the copper film, the thickness of the copper bottom layer is at least 1 μm, and the thickness of the thickened metal layer is greater than or equal to the thickness of the copper bottom layer.

[0007] Generally, the glass substrate is a transparent glass substrate with a thickness of 0.3 to 5 mm.

[0008] Generally, the copper film is deposited on the glass substrate by magnetron sputtering technology, and then the required pattern is formed by photolithography technology to form the copper bottom layer of the driving circuit and each pad; the thickened metal layer can be further grown on the copper bottom layer by electroplating or other methods. Generally, a gold film for improving solderability is also provided on the thickened metal layer, such as a gold film with a thickness of 100 to 500 nm.

[0009] In the structure of the above-mentioned Mini-LED display screen, since each soldering pad is composed of a copper base layer and a thickened metal layer, the thickened metal layer is arranged on the copper base layer, thereby increasing the overall thickness of the soldering pad, and then the two pins at the bottom of the LED are welded to the thickened soldering pad, which not only makes the entire soldering pad stronger to reduce the damage to the driving circuit caused by the thermal expansion and contraction of the LED, but also raises the position of the LED, so that the shear strain and stress caused by the thermal expansion and contraction of the LED are dispersed in the vertical direction, thereby avoiding failures caused by breakage of the driving circuit.

[0010] As a preferred solution of the present invention, the thickness of the thickened metal layer is at least 2 μm.

[0011] As a preferred solution of the present invention, the thickened metal layer extends along the surface of the copper bottom layer to outside the pad. Thus, the thickened metal layer can transfer the shear strain caused by the thermal expansion and contraction of the LED to outside the pad, so as to disperse the shear force to the area outside the pad, thereby avoiding the shear force being concentrated at the bottom of the pad and causing damage to the driving circuit.

[0012] As a further preferred embodiment of the present invention, the thickened metal layer is a nickel-phosphorus alloy layer. Generally, in the nickel-phosphorus metal layer, the ratio of the number of phosphorus atoms to the total number of atoms is at least 1:8. This nickel-phosphorus metal layer is an amorphous structure, has a very high hardness, and is also easy to be made through a relatively mature chemical nickel plating process. When it is designed to extend outside the pad along the copper bottom layer, it can more effectively transfer the shearing effect caused by the thermal expansion and contraction of the LED to the outside of the pad, and disperse the shearing force to the area outside the pad, avoiding the damage caused by the shearing force being concentrated at the bottom of the pad.

[0013] As a preferred solution of the present invention, the thickened metal layer is a nickel metal layer. The nickel metal layer can be formed by a chemical nickel plating process, and its manufacturing process is relatively simple.

[0014] As a preferred embodiment of the present invention, a nickel-chromium alloy layer is provided between the copper film and the glass substrate. Generally, the thickness of the nickel-chromium alloy layer is at most 100 nm. The nickel-chromium alloy layer is used to improve the adhesion of the copper film on the glass substrate, and can further prevent the pad from peeling off due to thermal expansion and contraction of the LED.

[0015] As a preferred solution of the present invention, the Mini-LED display screen further includes a cushioning layer, which is arranged under the LED. Thus, the position of the LED can be further raised by the cushioning layer, and the shear strain and stress caused by the thermal expansion and contraction of the LED can be dispersed in the vertical direction by appropriately thickening the solder between the LED and the pad.

[0016] As a further preferred embodiment of the present invention, the thickness of the cushioning layer is 2-10 μm.

[0017] As a further preferred embodiment of the present invention, the cushioning layer is an insulating layer.

[0018] As a further preferred embodiment of the present invention, the cushioning layer is made of resin coating.

[0019] As a further preferred embodiment of the present invention, the padding layer is a photosensitive resin coating, which can be exposed and developed to form a pattern under the LED, thereby avoiding the pad position at least.

[0020] As a further preferred solution of the present invention, the padding layer covers the line ends of the driving circuit, thereby preventing the line ends of the driving circuit from warping.

[0021] As a preferred solution of the present invention, the thickened metal layer forms a convex edge at the line end of the driving circuit, and the convex edge is embedded in the padding layer, thereby improving the combination of the padding layer and the thickened metal layer, and further preventing the line end of the driving circuit from warping.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] This Mini-LED display not only makes the soldering pad stronger, reducing damage to the driving circuit due to thermal expansion and contraction of the LED, but also disperses the shear strain and stress caused by thermal expansion and contraction of the LED in the vertical direction, thereby avoiding failures caused by breakage of the driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a Mini-LED display screen in the prior art.

[0025] Figure 2 yes Figure 1 Schematic diagram of the status of the Mini-LED display when it fails.

[0026] Figure 3 It is a structural schematic diagram of a Mini-LED display screen according to Example 1 of a preferred implementation manner of the present invention.

[0027] Figure 4 It is a structural schematic diagram of a Mini-LED display screen according to Example 2 of a preferred implementation manner of the present invention.

[0028] Figure 5 It is a structural schematic diagram of the Mini-LED display screen of Example 3 of the preferred implementation manner of the present invention. DETAILED DESCRIPTION

[0029] Embodiment 1: Figure 3 As shown, the Mini-LED display screen includes a glass substrate 1, a driving circuit 2 composed of a copper film 20 is provided on the first surface of the glass substrate 1, a plurality of pairs of pads 3 forming an array are provided on the driving circuit 2, and an LED 4 is respectively soldered on each pair of pads 3 (two pins 41 of the LED 4 are soldered to the two pads 3 in a pair through solder 5); each pad 3 includes a copper bottom layer 31 and a thickened metal layer 32 arranged on the copper bottom layer 31, the copper bottom layer 31 is composed of the copper film 20, the thickness of the copper bottom layer 31 is at least 1 μm, and the thickness of the thickened metal layer 32 is greater than or equal to the thickness of the copper bottom layer 31.

[0030] In this embodiment, the glass substrate 1 is a transparent glass substrate with a thickness of 0.3-5 mm.

[0031] In this embodiment, the copper film 20 is deposited on the glass substrate 1 by magnetron sputtering technology, and then the required pattern is formed by photolithography technology to form the copper bottom layer 31 of the driving circuit 2 and each pad 3; the thickened metal layer 32 can be further grown on the copper bottom layer 31 by electroplating or other methods.

[0032] In this embodiment, the thickness of the thickened metal layer 32 is at least 2 μm.

[0033] In this embodiment, the thickened metal layer 32 extends along the surface of the copper bottom layer 31 to the outside of the pad 3, and the thickened metal layer 32 is a nickel-phosphorus alloy layer. As a result, the thickened metal layer 32 can transfer the shear strain caused by the thermal expansion and contraction of the LED 4 to the outside of the pad 3, so as to disperse the shear force to the area outside the pad 3, thereby avoiding the damage to the driving circuit 2 caused by the concentration of the shear force at the bottom of the pad 3. In the nickel-phosphorus metal layer, the ratio of the number of phosphorus atoms to the total number of atoms is at least 1:8. This nickel-phosphorus metal layer is an amorphous structure, which has a very high hardness and is also easy to be made by a relatively mature chemical nickel plating process. When it is designed to extend along the copper bottom layer 31 to the outside of the pad 3, it can more effectively transfer the shearing effect caused by the thermal expansion and contraction of the LED 4 to the outside of the pad 3, disperse the shear force to the area outside the pad 3, and avoid the damage caused by the concentration of the shear force at the bottom of the pad 3.

[0034] Example 2: Reference Figure 4 , when other parts are the same as those of the first embodiment, the difference is that the Mini-LED display screen further includes a cushioning layer 6, which is arranged under the LED 4. Thus, the position of the LED 4 can be further raised by the cushioning layer 6, and the shear strain and stress caused by the thermal expansion and contraction of the LED 4 can be dispersed in the vertical direction by appropriately thickening the solder between the LED 4 and the pad 3.

[0035] In this embodiment, the padding layer 6 is a photosensitive resin coating, and the thickness of the padding layer 6 is 2-10 μm. The photosensitive resin coating can form a pattern under the LED 4 through exposure and development, thereby making it at least avoid the position of the pad 3.

[0036] In this embodiment, the padding layer 6 covers the line end of the driving circuit 2. Therefore, the padding layer 6 can prevent the line end of the driving circuit 2 from being lifted.

[0037] Example 3: Reference Figure 5 , when other parts are the same as those of the second embodiment, the difference is that in this embodiment, the thickened metal layer 32 forms a convex edge 321 at the line end of the driving circuit 2, and the convex edge 321 is embedded in the padding layer 6. This can improve the combination of the padding layer 6 and the thickened metal layer 32, and can further prevent the line end of the driving circuit 2 from warping.

[0038] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles of the patent concept of the present invention are included in the protection scope of the patent of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A Mini-LED display screen, comprising a glass substrate, a driving circuit composed of a copper film is provided on a first surface of the glass substrate, a plurality of pairs of pads forming an array are provided on the driving circuit, and an LED is respectively welded to each pair of pads, wherein: Each of the pads includes a copper bottom layer and a thickened metal layer arranged on the copper bottom layer, the copper bottom layer is composed of the copper film, the thickness of the copper bottom layer is at least 1μm, and the thickness of the thickened metal layer is greater than the thickness of the copper bottom layer; the Mini-LED display screen also includes a padding layer, which is arranged under the LED, the thickness of the padding layer is 2 to 10μm, and the thickened metal layer forms a convex edge at the line end of the driving circuit, and the convex edge is embedded in the padding layer.

2. A Mini-LED display screen according to claim 1, characterized in that: The copper film is deposited on the glass substrate by magnetron sputtering technology, and then the required pattern is formed by photolithography technology to form the copper bottom layer of the driving circuit and each of the pads; the thickened metal layer is grown on the copper bottom layer by electroplating.

3. The Mini-LED display screen according to claim 1, characterized in that: The thickness of the thickened metal layer is at least 2 μm.

4. The Mini-LED display screen according to claim 1, characterized in that: The thickened metal layer extends along the surface of the copper bottom layer and beyond the pad.

5. The Mini-LED display screen according to claim 4, characterized in that: The thickened metal layer is a nickel-phosphorus alloy layer.

6. The Mini-LED display screen according to claim 1, characterized in that: The thickened metal layer is a nickel metal layer.

7. A Mini-LED display according to any one of claims 1 to 6, characterized in that: A nickel-chromium alloy layer is provided between the copper film and the glass substrate.

8. A Mini-LED display according to any one of claims 1 to 6, characterized in that: The cushioning layer is an insulating layer.

9. A Mini-LED display according to any one of claims 1 to 6, characterized in that: The cushioning layer is coated with resin.

10. The Mini-LED display screen according to claim 9, characterized in that: The cushioning layer is coated with a photosensitive resin.

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