CN112103384A - Mini LED screen structure and packaging method thereof - Google Patents

Abstract

The invention discloses a packaging method for a Mini LED screen. A TFT driving device is produced, a metal reflective film is formed on the back of the TFT driving device, the electrodes of the TFT driving device pass through the metal reflective film; an LED light-emitting unit is fabricated on the metal reflective film, and the LED The electrode of the light-emitting unit is connected with the electrode of the TFT driving device, and the LED light-emitting unit array is arranged on the metal reflective film; the packaging glue is made, and the height of the sealing glue is lower than the height of the LED light-emitting unit; the transparent water and oxygen absorption layer is made to absorb water and oxygen The layer is covered on the encapsulation glue and the LED light-emitting unit; the nitride encapsulation film is made on the water and oxygen absorption layer. It protects the Mini LED chip and prolongs the life of the Mini LED screen. The nitride encapsulation film isolates the entry of external water and oxygen, and the metal reflective film reflects the light emitted by the TFT drive device back to the direction of the screen, increasing the brightness of the display. .

Description

A Mini LED screen structure and its packaging method

technical field

The invention belongs to the field of Mini LED screens, and in particular relates to a Mini LED screen structure and a packaging method thereof.

Background technique

Mini LED (mini Light Emitting Diode) is a sub-millimeter light-emitting diode, which is characterized by lightness and thinness, low power consumption, good flexibility, high bendability, good color gamut range, and can finely adjust the dimming zone performance to achieve higher HDR and contrast. It has become the focus of market attention now.

Mini LED backlight technology adopts the form of flip-chip packaging, which avoids the need for lens secondary optical design in traditional edge-lit backlights, achieves uniform light mixing, and achieves higher contrast effects; and Mini LED backlights are driven by arrays to achieve dynamic areas. Dimming, to achieve higher and finer toning, make the LCD screen higher contrast, improve the screen display effect;

Mini LED backlight has high brightness and higher power consumption than OLED. Currently, a reflective film is attached to the metal plate of the backlight source, and the light irradiated by the LED on the metal plate is reflected on the LCD substrate through the emissive film to improve the light of the LED. The utilization rate is high, and more precise high-brightness dimming is realized; however, the cost of the reflective film is high, and the posting of the reflective film increases the cost of the product and the process steps;

At present, MinilLED screens are mostly driven by metal oxide TFTs, but metal oxide TFTs use IGZO film as the active layer. IGZO film is very sensitive to water and oxygen, and in the packaging process of MiniLED display, the LED lamp is fixed and then coated with silica gel for packaging. Silica gel has poor blocking ability to water and oxygen, and the side of the LED chip is easily eroded by water vapor, and the active layer IGZO film in the underlying TFT driver is prone to device failure due to water and oxygen infection.

SUMMARY OF THE INVENTION

To this end, it is necessary to provide a Mini LED screen structure and its packaging method, which can improve the brightness of the Mini LED screen, adjust the dimming zone more finely, improve the contrast of the liquid crystal display, and enable the Mini LED screen to have good isolation of water, oxygen and The ability to absorb water and oxygen that has invaded the film improves the stability and service life of the metal reflective film and the TFT drive device, thereby achieving a higher brightness display effect.

In order to achieve the above purpose, the present application provides a packaging method for a Mini LED screen, comprising the steps of:

making a TFT driving device, and making a metal reflective film on the back of the TFT driving device, and the electrode of the TFT driving device passes through the metal reflective film;

A plurality of LED light-emitting units are fabricated on the metal reflective film, electrodes of the LED light-emitting units are connected to electrodes of the TFT driving device, and a plurality of the LED light-emitting unit arrays are arranged on the metal reflective film;

Making an encapsulant, the height of the encapsulant is lower than the height of the LED light-emitting unit;

making a transparent water-oxygen absorbing layer, the water-oxygen absorbing layer covering the encapsulant and the LED light-emitting unit;

A nitride encapsulation film is fabricated on the water-oxygen absorbing layer.

Further, it also includes the steps:

A stress buffer layer is formed on the nitride encapsulation film.

Further, the metal reflective film is an Ag reflective film.

Further, the encapsulating glue is encapsulating silica gel, and the encapsulating silica gel is used to fix the position of the LED light-emitting unit.

Further, the nitride encapsulation film is a silicon nitride encapsulation film.

Further, the stress buffer layer is a polyimide stress buffer layer, and the polyimide stress buffer layer is used for releasing stress and protecting the Mini LED screen.

In order to achieve the above purpose, the present application also provides a Mini LED screen structure, including: a TFT drive device, a metal reflective film, an LED light-emitting unit, an encapsulation glue, a water-oxygen absorption layer and a nitride encapsulation film;

A metal reflective film is arranged on the back of the TFT driving device, and the electrodes of the TFT driving device pass through the metal reflective film; a plurality of LED light-emitting units are arranged on the metal reflective film, and the electrodes of the LED light-emitting units are connected to the The electrodes of the TFT driving device are connected, and a plurality of the LED light-emitting unit arrays are arranged on the metal reflective film; the plurality of the LED light-emitting units in the array are directly filled with the encapsulant, and the encapsulant The height is lower than the height of the LED light-emitting unit; the water-oxygen absorption layer covers the encapsulation glue and the LED light-emitting unit; a nitride packaging film is arranged on the water-oxygen absorption layer.

Further, it also includes: a stress buffer layer; a stress buffer layer is provided on the nitride encapsulation film, and the stress buffer layer is used for releasing stress and protecting the Mini LED screen.

Further, the thickness of the metal reflective film ranges from 0.05um to 0.2um.

Further, the height of the water and oxygen absorbing layer is equal to that of the nitride encapsulation film.

Different from the prior art, the above technical solution distributes the LED light-emitting units in an array on the TFT driving device with the metal reflective film, and connects the electrode pads of the LED light-emitting unit with the electrodes of the corresponding TFT driving device, and then coats the The encapsulation glue is used for encapsulation. The height of the encapsulation glue is not higher than the height of the LED light-emitting unit. A transparent water and oxygen absorbing layer is used to fill the pores between the LED light-emitting units. The water and oxygen absorbing layer is used to absorb the water and oxygen that penetrates into the Mini LED screen. , plays the role of protecting the Mini LED chip and prolonging the life of the Mini LED screen. Finally, a layer of nitride encapsulation film is deposited for film encapsulation to isolate the entry of external water and oxygen, and the metal reflective film reflects the light emitted by the TFT drive device back. To the direction of light output from the screen, it can increase the brightness of the display and reduce the influence of the LED light-emitting unit on the side of the underlying TFT driving device, thereby improving the stability of the driving device.

Description of drawings

FIG. 1 is a structural diagram of the Mini LED screen;

FIG. 2 is a flow chart of manufacturing the encapsulant and the LED light-emitting unit according to the specific embodiment;

FIG. 3 is a flow chart of making the water-oxygen absorbing layer in a specific embodiment;

FIG. 4 is a step diagram of a packaging method of a Mini LED screen according to the specific embodiment.

Description of reference numbers:

1. TFT drive device; 2. Encapsulation glue; 3. LED light-emitting unit; 4. Metal reflection film; 5. Nitride packaging film; 6. Water and oxygen absorption layer; 7. Stress buffer layer.

Detailed ways

In order to describe in detail the technical content, structural features, achieved objectives and effects of the technical solution, the following detailed description is given in conjunction with specific embodiments and accompanying drawings.

Referring to FIGS. 1 to 4 , this embodiment provides a packaging method for a Mini LED screen, including the steps of: fabricating a TFT driving device 1 , and fabricating a metal reflective film 4 on the back of the TFT driving device 1 , and the TFT driving device 1 The electrodes of the device 1 pass through the metal reflective film 4; a plurality of LED light-emitting units 3 are fabricated on the metal reflective film 4, and the electrodes of the LED light-emitting units 3 are connected to the electrodes of the TFT driving device 1. The LED light-emitting units 3 are arranged in an array on the metal reflective film 4; an encapsulant 2 is made, and the height of the encapsulant 2 is lower than the height of the LED light-emitting unit 3; a transparent water and oxygen absorption layer 6 is made, so The water-oxygen absorbing layer 6 is covered on the encapsulant 2 and the LED light-emitting unit 3; a nitride encapsulation film 5 is made on the water-oxygen absorbing layer 6; that is, the encapsulant 2 is placed in a plurality of Between the LED light-emitting units 3, the gap between the LED light-emitting unit 3 and the LED light-emitting unit 3 is filled; similarly, the water-oxygen absorption layer 6 covers the plurality of the LED light-emitting units 3, and fills the gap between the LED light-emitting units 3 and the LED light-emitting units 3; The gap between the LED light-emitting unit 3 and the LED light-emitting unit 3 . The encapsulating glue 2 is encapsulating silica gel. It should be noted that, in the present application, the motor connecting the TFT driving device 1 and the LED light-emitting unit 3 is exposed from the metal reflective film 4 to facilitate connection with the electrodes of the LED light-emitting unit 3 . It should be further noted that, before the Mini LED screen is flip-chip transferred to the TFT drive device 1 process, a metal reflective film 4 is prepared and deposited on the back of the TFT drive, as the reflective layer of the LED light-emitting unit 3, which serves to illuminate the LED light. The light entering the TFT driving direction is reflected in the opposite direction, which can improve the brightness of the display and protect the stability of the TFT driving device 1 . Due to the limited ability of the traditional encapsulant 2 to isolate water and oxygen; after making the LED light-emitting unit 3, please refer to FIG. 2 to encapsulate the encapsulant 2, and the height of the encapsulant 2 does not exceed the LED light-emitting unit. 3 height, a transparent water and oxygen absorbing layer 6 is coated between the LED light-emitting units 3, please refer to FIG. The light-emitting unit 3 is completely covered, that is, the sum of the heights of the water-oxygen absorbing layer 6 and the encapsulation layer is greater than the height of the LED light-emitting unit 3 . The water and oxygen absorbing layer 6 and the encapsulation layer avoid the defect of the limited water and oxygen isolation capability of the encapsulant 2, thereby protecting the life of the Mini LED screen and preventing the erosion of the metal reflective film 4 by water and oxygen. Then, a layer of nitride encapsulation film 5 is deposited on the device by PECVD (chemical vapor deposition), and the ability of the nitride encapsulation film 5 to isolate water and oxygen can reach WVRT (water vapor transmission rate)≤5E-05 (g/m2 -day), which plays a role in completely isolating water and oxygen. In the above technical solution, the LED light-emitting units 3 are distributed in an array on the TFT driving device 1 with the metal reflective film 4, and the electrode pads of the LED light-emitting unit 3 are connected with the electrodes of the corresponding TFT driving device 1, and then coated and packaged. Glue 2 is used for encapsulation, and the height of the encapsulation glue 2 does not completely exceed the height of the LED light-emitting unit 3. A transparent water and oxygen absorbing layer 6 is used to fill the pores between the LED light-emitting units 3. The water and oxygen absorbing layer 6 is used to absorb and penetrate into the Mini LED. The water and oxygen in the screen play a role in protecting the Mini LED chip and prolonging the life of the Mini LED screen. Finally, a layer of nitride encapsulation film 5 is deposited for film encapsulation to isolate the entry of external water and oxygen, and the metal reflective film 4 plays the role of directing the light to the TFT. The light emitted by the driving device 1 is reflected back to the direction of light output from the screen, which increases the brightness of the display and reduces the influence of the LED light-emitting unit 3 on the lower TFT driving device 1 side, thereby improving the stability of the driving device.

Referring to FIG. 1 , in order to further protect the Mini LED screen, in some embodiments, a step of forming a stress buffer layer 7 on the nitride encapsulation film is further included. It should be noted that the material of the last coating layer of the stress buffer layer 7 is PI (polyimide); it plays the role of stress releasing and buffering external impact, and this laminated thin film package replaces the traditional single-layer silica gel Encapsulation improves the ability of the device to block water and oxygen, prolongs the service life of the Mini LED screen, improves the stability of the TFT drive device 1, and realizes high-brightness and high-contrast display of the display.

It should be further noted that the metal reflective film 4 is an Ag reflective film. The encapsulating glue 2 is encapsulating silica gel, and the encapsulating silica gel is used to fix the position of the LED light-emitting unit 3 . The nitride encapsulation film 5 is a silicon nitride encapsulation film. The stress buffer layer 7 is a polyimide stress buffer layer 7, and the polyimide stress buffer layer 7 is used for releasing stress and protecting the Mini LED screen. specific,

In order to improve the utilization rate of the LED light-emitting unit 3 of the backlight, the light reflected from the TFT driving device 1 needs to be re-reflected. Due to the low extinction coefficient and high reflectivity of the metal reflective film 4, the metal reflective film 4 can be deposited by PVD. A layer of metal Ag (silver), the reflectivity of the metal thin film silver can reach 98.8%, the reflective film material selection is no less than aluminum, chromium, platinum, and its thickness ranges from 0.05um to 0.2um, preferably 0.15um. Since the metal film reflective layer is easy to react with external water vapor and oxygen, a transparent water-oxygen absorbing layer 6 is coated between the LED light-emitting units 3 above the encapsulant 2. The water-oxygen absorbing layer 6 can be made of magnesium oxide or oxide Barium, etc., preferably magnesium oxide, and the thickness of the water-oxygen absorbing layer 6 ranges from 0.1um to 0.3um, preferably 0.15um. A layer of nitride encapsulation film 5 is deposited on the water and oxygen absorption layer 6. The nitride encapsulation film 5 can be SiNx. The nitride encapsulation film 5 plays the role of protecting the LED light-emitting unit 3 and the metal reflective film 4. The thickness of the thin film 5 ranges from 0.1 um to 0.3 um, preferably 0.15 um. The outermost organic buffer layer in the Mini LED screen structure is coated with an organic film by IJP or a coating machine.

Please refer to FIG. 4 . The specific process is as follows. The glass substrate is cleaned and baked by a cleaning machine and a baking machine to make a metal oxide TFT driving device 1 , and then the metal reflective film 4 is prepared by PVD on the back of the TFT driving device 1 , and then The LED light-emitting unit 3 is arrayed on the TFT driving device 1, and the LED light-emitting unit 3 and the TFT driving device 1 are cured by coating the encapsulant 2 and then curing, and the electrodes forming the LED light-emitting unit 3 are welded. The disk is connected to the electrodes of the TFT driving device 1, and a layer of the water-oxygen absorbing layer 6 is prepared between the plurality of the LED light-emitting units 3 to absorb the water vapor and oxygen that have invaded from the outside, and then deposit nitrogen from the outside by PECVD. Finally, a layer of stress buffer layer 7 is coated by Coater for stress release and external impact buffer layer, and finally the preparation of Mini LED screen is formed.

Referring to FIG. 1 , this embodiment provides a Mini LED screen structure, including: a TFT driving device 1 , a metal reflective film 4 , an LED light-emitting unit 3 , an encapsulant 2 , a water-oxygen absorption layer 6 and a nitride encapsulation film 5 ; A metal reflective film 4 is arranged on the back of the TFT driving device 1, and the electrodes of the TFT driving device 1 pass through the metal reflective film 4; a plurality of LED light-emitting units 3 are arranged on the metal reflective film 4, and the The electrodes of the LED light-emitting units 3 are connected to the electrodes of the TFT driving device 1, and a plurality of the LED light-emitting units 3 are arranged in an array on the metal reflective film 4; the plurality of the LED light-emitting units 3 in the array are directly filled with There is the encapsulant 2, and the height of the encapsulant 2 is lower than the height of the LED light-emitting unit 3; the water-oxygen absorption layer 6 covers the encapsulant 2 and the LED light-emitting unit 3; A nitride encapsulation film 5 is arranged on the water and oxygen absorption layer 6 . The encapsulating glue 2 is encapsulating silica gel. The encapsulating glue 2 is encapsulating silica gel. It should be noted that, in the present application, the motor connecting the TFT driving device 1 and the LED light-emitting unit 3 is exposed from the metal reflective film 4 to facilitate connection with the electrodes of the LED light-emitting unit 3 . It should be further noted that the metal reflective film 4 is used as the reflective layer of the LED light-emitting unit 3 to irradiate the LED light into the TFT driving direction, and reflect it in the opposite direction, which can improve the brightness of the display and protect the TFT driving Device 1 stability. Because the traditional encapsulation glue 2 has limited ability to isolate water and oxygen; after the LED light-emitting unit 3 is arranged, an encapsulation glue 2 is provided, and the encapsulation glue 2 is encapsulated silica gel, and the height of the encapsulation glue 2 does not exceed all The height of the LED light-emitting unit 3, a transparent water-oxygen absorbing layer 6 is arranged between the LED light-emitting units 3 to absorb the water and oxygen that penetrates into the film layer from the outside; 3 is completely covered, that is, the sum of the heights of the water-oxygen absorbing layer 6 and the encapsulation layer is greater than the height of the LED light-emitting unit 3 . The water-oxygen absorbing layer 6 and the encapsulation layer avoid the defect that the encapsulation glue 2 has limited ability to isolate water and oxygen, thereby protecting the life of the Mini LED screen and preventing the erosion of the metal reflective film 4 by water and oxygen. The nitride encapsulation film 5 disposed on the water-oxygen absorbing layer 6 can isolate water and oxygen up to WVRT (water vapor transmission rate) ≤ 5E-05 (g/m2-day), thus achieving complete isolation The role of water oxygen. In the above technical solution, the LED light-emitting units 3 are distributed in an array on the TFT driving device 1 with the metal reflective film 4, and the electrode pads of the LED light-emitting unit 3 are connected with the electrodes of the corresponding TFT driving device 1, and then coated and packaged. Glue 2 is used for encapsulation, and the height of the encapsulation glue 2 does not completely exceed the height of the LED light-emitting unit 3. A transparent water and oxygen absorbing layer 6 is used to fill the pores between the LED light-emitting units 3. The water and oxygen absorbing layer 6 is used to absorb and penetrate into the Mini LED. The water and oxygen in the screen play a role in protecting the Mini LED chip and prolonging the life of the Mini LED screen. Finally, a layer of nitride encapsulation film 5 is deposited for film encapsulation to isolate the entry of external water and oxygen, and the metal reflective film 4 plays the role of directing the light to the TFT. The light emitted by the driving device 1 is reflected back to the direction of light output from the screen, which increases the brightness of the display and reduces the influence of the LED light-emitting unit 3 on the lower TFT driving device 1 side, thereby improving the stability of the driving device.

Referring to FIG. 1, in order to further protect the Mini LED screen, in some embodiments, it further includes: a stress buffer layer 7; a stress buffer layer 7 is provided on the nitride encapsulation film, and the stress buffer layer 7 is used for Relieve stress and protect MiniLED screen. The stress buffer layer 7 plays the role of stress release and buffering of external impact. This laminated thin film package replaces the traditional single-layer silicone package, which improves the device's ability to block water and oxygen, prolongs the service life of the Mini LED screen, and improves the TFT drive. The stability of the device 1 realizes high brightness and high contrast display of the display.

In order to improve the utilization rate of the LED light-emitting unit 3 of the backlight, the light reflected from the TFT driving device 1 needs to be re-reflected. Due to the low extinction coefficient and high reflectivity of the metal reflective film 4, the metal reflective film 4 can be deposited by PVD. A layer of metal Ag (silver), the reflectivity of the metal thin film silver can reach 98.8%, the reflective film material selection is no less than aluminum, chromium, platinum, and its thickness ranges from 0.05um to 0.2um, preferably 0.15um. The height of the water and oxygen absorption layer 6 is equal to the height of the nitride encapsulation film 5 . Since the metal film reflective layer is easy to react with external water vapor and oxygen, a transparent water-oxygen absorbing layer 6 is coated between the LED light-emitting units 3 above the encapsulant 2. The water-oxygen absorbing layer 6 can be made of magnesium oxide or oxide Barium, etc., preferably magnesium oxide, and the thickness of the water-oxygen absorbing layer 6 ranges from 0.1um to 0.3um, preferably 0.15um. A layer of nitride encapsulation film 5 is deposited on the water and oxygen absorption layer 6. The nitride encapsulation film 5 can be SiNx. The nitride encapsulation film 5 plays the role of protecting the LED light-emitting unit 3 and the metal reflective film 4. The thickness of the thin film 5 ranges from 0.1 um to 0.3 um, preferably 0.15 um. The outermost organic buffer layer in the Mini LED screen structure is coated with an organic film by IJP or a coating machine.

It should be noted that, although the above embodiments have been described herein, it does not limit the scope of the patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications to the embodiments described herein, or equivalent structures or equivalent process transformations made by using the contents of the description and drawings of the present invention, directly or indirectly apply the above technical solutions In other related technical fields, all are included within the scope of patent protection of the present invention.

Claims (10)

1. A method for packaging a Mini LED screen is characterized by comprising the following steps:

manufacturing a TFT driving device, and manufacturing a metal reflecting film on the back surface of the TFT driving device, wherein an electrode of the TFT driving device penetrates through the metal reflecting film;

manufacturing a plurality of LED light-emitting units on the metal reflective film, wherein electrodes of the LED light-emitting units are connected with electrodes of the TFT driving device, and the LED light-emitting units are arrayed on the metal reflective film;

manufacturing packaging glue, wherein the height of the packaging glue is lower than that of the LED light-emitting unit;

manufacturing a transparent water and oxygen absorption layer, wherein the water and oxygen absorption layer covers the packaging adhesive and the LED light-emitting unit;

and manufacturing a nitride packaging film on the water-oxygen absorption layer.

2. The method for encapsulating a Mini LED screen according to claim 1, further comprising the steps of:

and manufacturing a stress buffer layer on the nitride packaging film.

3. The method for encapsulating a Mini LED screen according to claim 1, wherein the metal reflective film is an Ag reflective film.

4. The method for packaging a Mini LED screen according to claim 1, wherein the packaging adhesive is packaging silica gel, and the packaging silica gel is used for fixing the position of the LED light-emitting unit.

5. The method for encapsulating a Mini LED screen according to claim 1, wherein the nitride encapsulation film is a silicon nitride encapsulation film.

6. The method for encapsulating the Mini LED screen according to claim 2, wherein the stress buffer layer is a polyimide stress buffer layer, and the polyimide stress buffer layer is used for releasing stress and protecting the Mini LED screen.

7. A Mini LED screen structure, comprising: the LED packaging structure comprises a TFT driving device, a metal reflecting film, an LED light-emitting unit, packaging glue, a water-oxygen absorption layer and a nitride packaging film;

arranging a metal reflecting film on the back surface of the TFT driving device, wherein an electrode of the TFT driving device penetrates through the metal reflecting film; a plurality of LED light-emitting units are arranged on the metal reflecting film, electrodes of the LED light-emitting units are connected with electrodes of the TFT driving device, and the LED light-emitting units are arrayed on the metal reflecting film; the packaging glue is directly filled in the plurality of LED light-emitting units of the array, and the height of the packaging glue is lower than that of the LED light-emitting units; the water and oxygen absorption layer covers the packaging adhesive and the LED light-emitting unit; and arranging a nitride packaging film on the water-oxygen absorption layer.

8. The Mini LED screen structure of claim 7, further comprising: a stress buffer layer; and arranging a stress buffer layer on the nitride packaging film, wherein the stress buffer layer is used for releasing stress and protecting the Mini LED screen.

9. The Mini LED screen structure of claim 7, wherein the thickness of the metal reflective film is in the range of 0.05um to 0.2 um.

10. The Mini LED panel structure of claim 7, wherein the water oxygen absorption layer is at the same height as the nitride encapsulation film.

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