Glass-based Mini LED backlight substrate and preparation method thereof

Abstract

The invention discloses a glass-based Mini LED backlight substrate and a preparation method thereof, and belongs to the technical field of backlight display. According to the invention, the groove line with a certain depth is etched on the glass substrate, then Cu slurry (or Ag slurry or electroplated Cu) is used for filling to form the circuit wiring, the positive wiring and the negative wiring are arranged in the glass substrate, and the glass substrate can be used as an insulating medium layer, so that the problem of poor gaps of solder mask ink caused by poor step coverage is eliminated, and the production efficiency is improved. And meanwhile, the characteristics of natural high compactness, high insulation and the like of the glass are utilized, so that an electrochemical migration path between the wiring of the positive electrode and the wiring of the negative electrode can be effectively blocked, and the reliability of the product is improved.

Description

Technical Field

[0001] The present invention relates to the field of backlight display technology, and in particular to a glass-based Mini LED backlight substrate and a preparation method thereof. Background Art

[0002] The biggest feature of OLED is self-luminescence. Each pixel behind the display device can be controlled individually, so it performs well in terms of brightness and contrast. Its extra thinness and bendability are favored by electronic equipment manufacturers. Among them, Mini-LED, as a new type of liquid crystal backlight technology of LCD display technology, uses a diode light source with a smaller unit. Compared with the traditional direct-down backlight technology, the lamp beads of Mini-LED are only 1 / 40 of the size of traditional lamp beads, which means that there will be more dimming areas in the same area; when the Mini-LED backlight partitions increase exponentially, it can bring ultra-high contrast, ultra-high brightness and ultra-high color gamut, and will not produce the afterimage and burn-in problems caused by the long-term opening of the OLED screen, so Mini-LED is more suitable for large-screen display devices, such as TVs or e-sports screens.

[0003] The current glass-based Mini LED backlight products deposit a thick Cu film on the glass substrate, and complete the metal patterning by exposure and etching to form the positive and negative wiring of the LED and the multi-channel wiring of the driver IC. After that, the solder mask ink (reflective white oil) with insulating isolation is applied, and the Pad window opening and gold immersion process are performed, and finally the LED chip packaging process is completed. In this scheme, the Cu (or Ag) metal wiring is distributed on the surface of the glass substrate, and the positive and negative wirings are isolated by the coated organic glue material solder mask ink, that is, reflective white oil. Due to the high metal wiring step difference, gaps and other defects caused by poor step coverage often occur in the glue coating process. At the same time, although the organic glue material has certain insulation properties, it is inevitable that there will be more pinhole gaps inside it during the coating process. In the reliability aging test of subsequent products, these gaps, pinholes and other defects will become the transmission channels of water vapor and oxygen, causing the organic dielectric layer to deteriorate, and ultimately leading to poor electrochemical migration between the positive and negative electrode wirings, and the product will fail.

[0004] Based on the above problems, a glass-based Mini LED backlight substrate and a preparation method thereof are proposed. Summary of the invention

[0005] The object of the present invention is to provide a glass-based Mini LED backlight substrate and a preparation method thereof to solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides a glass-based Mini LED backlight substrate and a preparation method thereof. S1. According to the designed metal wiring arrangement structure, the glass substrate is irradiated with laser to induce degeneration in the irradiated area; S2, attaching a protective film to the back of the glass substrate processed in S1, performing HF etching on the front of the glass substrate, rapidly etching the induced denaturation area, and controlling the time to form a wiring groove on the glass substrate; S3, filling the wiring groove with conductive Cu paste, and after curing, polishing and flattening the entire surface of the glass substrate to remove excess Cu film on the substrate surface, and forming Cu circuit traces on the glass substrate; S4, remove the protective film on the back, apply solder mask ink on the front of the glass substrate, and then expose and develop the pad position of the wiring to open a window; S5. Perform gold deposition on the pad position after the window is opened. After completion, perform LED packaging, complete the die bonding and packaging of the LED chip, and obtain a glass-based Mini LED backlight substrate.

[0007] Preferably, in S2, the HF etching process is to immerse the glass substrate in a hydrofluoric acid or KOH solution, and control the etching depth by the etching time, and the etching time is 10 to 30 minutes.

[0008] Preferably, in S2, the protective film is applied by pasting a PET protective film or applying a UV blue film.

[0009] Preferably, in S3, the operation of filling the conductive Cu paste is specifically to fill the blanks by screen printing or 3D printing, and the curing process uses nitrogen curing, and the curing temperature is 180-220°.

[0010] Preferably, in S3, the operation of filling with conductive Cu paste is replaced by filling with conductive Ag paste or electroplating Cu.

[0011] Preferably, in S4, a mask is used to expose the pad position, and the exposed glass substrate is placed in a developer, and the unexposed solder mask ink is dissolved to expose the pad position to be soldered, thereby forming an opening.

[0012] Preferably, in S5, the glass substrate is pickled, activated, and subjected to nickel deposition and then gold deposition.

[0013] Preferably, the LED packaging process in S5 is to place the LED chip on the Pad position after the immersion gold treatment, use welding materials to fix the chip on the Pad, connect the electrodes of the LED chip with the Cu circuit traces through the Solder Bump to ensure good electrical connection, and use kens packaging glue to cover the LED chip to protect the chip from the influence of the external environment and provide mechanical support.

[0014] Therefore, the present invention provides a glass-based Mini LED backlight substrate and a preparation method thereof, by etching groove lines of a certain depth on the glass substrate, and then using Cu paste (or Ag paste, or electroplated Cu) to fill and form circuit wiring, and placing the positive and negative electrode wiring inside the glass substrate. The glass substrate can be used as an insulating dielectric layer, thereby eliminating the problem of poor gaps in the solder mask ink due to poor step coverage. At the same time, the natural high density, high insulation and other properties of the glass itself are utilized, so that the electrochemical migration path between the positive and negative electrode wiring can be effectively blocked, thereby improving the reliability of the product.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a glass substrate after being processed in step 1 according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a glass substrate after being processed in step 2 according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a glass substrate after being processed in step 3 according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a glass substrate after being processed in step 4 according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a glass substrate after the gold immersion treatment in step 5 according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a glass substrate after the LED packaging process in step 5 in an embodiment of the present invention; Figure 7 Schematic diagram of the positive and negative electrodes of the backlight substrate in an embodiment of the present invention; Figure 8 A schematic diagram of electrochemical migration leading to product failure in the conventional method of the present invention; Reference numerals: 1. Glass substrate; 2. Protective film; 3. Solder resist ink; 4. Immersion gold; 5. LED chip; 6. Lens encapsulation glue; 7. Solder Bump; 8. Wiring groove; 9. Cu circuit routing. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0019] Example This embodiment prepares a glass-based Mini LED backlight substrate, specifically as follows: S1. According to the pre-designed metal wiring arrangement structure, the glass substrate 1 is irradiated with laser, so that the area pre-filled with metal wiring is denatured due to the irradiation of high-energy laser, such as Figure 1 As shown; S2, a PET protective film 2 is attached to the back of the glass substrate 1 after S1 treatment to protect the back from corrosion by the etching solution, and then HF etching is performed on the front of the glass substrate 1 to quickly etch the induced denaturation area, and the time is controlled to form a wiring groove 8 on the glass substrate 1, as shown in FIG. Figure 2 As shown; S3, fill the wiring groove 8 with conductive Cu paste, solidify and shape it to completely fill the entire wiring groove 8, then perform CMP grinding and polishing on the entire surface of the glass substrate 1 to remove the excess Cu film on the substrate surface, and finally form the required Cu circuit trace 9 in the prefabricated glass wiring groove, such as Figure 3 As shown; S4. Carefully remove the previously adhered protective film 2 from the back of the glass substrate 1, ensuring that the wiring structure on the front is not damaged, apply solder mask ink 3 on the front of the glass substrate 1, and use a mask to expose the position to be welded (i.e., the pad position of the wiring). During the exposure process, ultraviolet light is irradiated onto the solder mask ink 3 through the mask, causing the ink in these areas to undergo chemical changes, which is convenient for subsequent development; put the exposed glass substrate 1 into the developer, the unexposed solder mask ink 3 will be dissolved, exposing the pad position to be welded, forming a window, such as Figure 4 shown.

[0020] S5, pickling, activating, nickel deposition and then gold deposition are performed on the pad position after the window is opened, and a layer of gold is covered on the surface of the copper layer, such as Figure 5 After completion, LED packaging is performed, the LED chip 5 is placed on the Pad position after the immersion gold 4 treatment, the chip is fixed on the Pad using welding materials, the electrode of the LED chip 5 is connected to the Cu circuit trace 9 through the SolderBump 7 to ensure good electrical connection, and the LED chip 5 is covered with Lens packaging glue 6 to protect the chip from the influence of the external environment and provide mechanical support, and the solid crystal bonding and packaging of the LED chip 5 are completed, as shown. Figure 6 shown.

[0021] The traditional method uses a swing arm or needle-piercing die bonding machine to package the chip on the glass substrate 1. As the high temperature / high humidity aging test progresses, the dielectric layer between the positive and negative electrode metal traces loaded with high bias voltage begins to deteriorate, and electrochemical migration occurs. Finally, a short circuit occurs between the positive and negative electrode metal traces, resulting in product failure. Figure 7 shown.

[0022] The glass-based Mini LED backlight substrate prepared by the above embodiment is compared with the traditional method. In this embodiment, a conductive line is arranged in the groove, and a glass insulator is placed between the two grooves. This effectively prevents the short circuit problem caused by ion migration of Cu wire or Ag wire under high temperature and high humidity charged operation. Figure 8 shown.

[0023] Therefore, the present invention provides a glass-based Mini LED backlight substrate and a preparation method thereof, by etching groove lines of a certain depth on the glass substrate, and then using Cu paste (or Ag paste, or electroplated Cu) to fill and form circuit wiring, and placing the positive and negative electrode wiring inside the glass substrate. The glass substrate can be used as an insulating dielectric layer, thereby eliminating the problem of poor gaps in the solder mask ink due to poor step coverage. At the same time, the natural high density, high insulation and other properties of the glass itself are utilized, so that the electrochemical migration path between the positive and negative electrode wiring can be effectively blocked, thereby improving the reliability of the product.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a glass-based Mini LED backlight substrate, characterized in that: The following steps are involved: S1. According to the designed metal wiring arrangement structure, the glass substrate is irradiated with laser to induce degeneration in the irradiated area; S2, covering the back of the glass substrate processed in S1 with a protective film, performing HF etching on the front of the glass substrate, rapidly etching the induced denaturation area, and controlling the time to form a wiring groove on the glass substrate; S3, filling the wiring groove with conductive Cu paste, and after curing, polishing and flattening the entire surface of the glass substrate to remove excess Cu film on the substrate surface, and forming Cu circuit traces on the glass substrate; S4, remove the protective film on the back, apply solder mask ink on the front of the glass substrate, and then expose and develop the pad position of the wiring to open a window; S5. Perform gold deposition on the pad position after the window is opened. After completion, perform LED packaging, complete the die bonding and packaging of the LED chip, and obtain a glass-based Mini LED backlight substrate.

2. The method for preparing a glass-based Mini LED backlight substrate according to claim 1, characterized in that: In S2, the HF etching process is to immerse the glass substrate in a hydrofluoric acid or KOH solution, and control the etching depth by the etching time, and the etching time is 10 to 30 minutes.

3. The method for preparing a glass-based Mini LED backlight substrate according to claim 2, characterized in that: In S2, the protective film is applied by pasting a PET protective film or applying a UV blue film.

4. The method for preparing a glass-based Mini LED backlight substrate according to claim 1, characterized in that: In S3, the operation of filling the conductive Cu paste is specifically to fill the blanks by screen printing or 3D printing, and the curing process uses nitrogen curing at a curing temperature of 180-220°.

5. The method for preparing a glass-based Mini LED backlight substrate according to claim 1, characterized in that: In S3, the operation of filling with conductive Cu paste is replaced by filling with conductive Ag paste or electroplating Cu.

6. The method for preparing a glass-based Mini LED backlight substrate according to claim 1, characterized in that: In S4, a mask is used to expose the pad position, and the exposed glass substrate is placed in a developer, and the unexposed solder mask ink is dissolved to expose the pad position to be soldered, thereby forming an opening.

7. The method for preparing a glass-based Mini LED backlight substrate according to claim 1, characterized in that: In S5, the glass substrate is pickled, activated, and nickel-deposited and then gold-deposited.

8. A glass-based Mini LED backlight substrate, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.

Images