Backlight and liquid crystal display

1. A backlight, comprising:

a circuit substrate;

a plurality of LED chips, the plurality of LED chips being fixed by means of die bond on the circuit substrate;

a first silica gel layer, the first silica gel layer being applied to the circuit substrate and wrapping the plurality of LED chips;

a phosphor layer applied to the first silica gel layer, the phosphor layer having a thickness less than 0.15 mm; and

a second silica gel layer disposed on the phosphor layer, the second silica gel layer being a silica gel layer mixed with diffusion powder;

wherein a surface of the first silica gel layer is flat, the surface of the first silica gel layer comprises a pattern of trenches, and a depth of each of the trenches is less than 0.05 mm.

2. The backlight according to claim 1 , wherein the first silica gel layer has a silica gel refractive index greater than 1.4, and the first silica gel layer has a thickness greater than 0.2 mm.

3. The backlight according to claim 1 , wherein a length of each LED chip is less than 0.5 mm; a width of each LED chip is less than 0.5 mm; and a height of the LED chip is less than 0.2 mm.

4. The backlight according to claim 1 , wherein the plurality of LED chips are fixed in an array by means of die bond on the circuit substrate.

5. The backlight according to claim 1 , wherein a distance between adjacent chips of the plurality of LED chips is less than 5 mm.

6. The backlight according to claim 1 , wherein a thickness of the circuit substrate is less than 0.5 mm.

7. A backlight, comprising:

a circuit substrate;

a plurality of LED chips disposed on the circuit substrate;

a reflective film disposed on the circuit substrate and comprising a plurality of openings corresponding to the plurality of LED chips; and

a diffusing layer disposed on the plurality of LED chips, the diffusing layer comprising a silica gel layer and a plurality of three-dimensional microstructures disposed on a surface of the silica gel layer, and the surface of the silica gel layer being away from the LED chip, wherein the silica gel layer is a transparent organosilica gel layer or an organosilica gel layer mixed with phosphor or quantum dots, and a thickness of the silica gel layer is between 0.1 mm and 1 mm.

8. The backlight according to claim 7 , wherein a reflectivity of the reflective film is greater than 90%, and a material of the reflective film comprises a polymer or a metal.

9. The backlight according to claim 7 , wherein the plurality of LED chips are distributed in a rectangular array, a circular array, or a special-shaped array on the circuit substrate.

10. The backlight according to claim 9 , wherein a distance between any two adjacent LED chips of the plurality of LED chips is between 0.1 mm and 10 mm.

11. The backlight according to claim 7 , wherein the LED chip has a length of between 0.05 mm and 0.5 mm, a width of between 0.05 mm and 0.5 mm, and a thickness of between 0.05 mm and 0.3 mm.

12. A liquid crystal display, comprising a display panel and the backlight according to claim 1 .

13. A method for manufacturing the backlight according to claim 7 , comprising:

providing the plurality of LED chips on the circuit substrate;

providing the plurality of openings in the reflective film corresponding to the plurality of LED chips;

providing the reflective film on the circuit substrate; and

providing the silica gel layer and the plurality of three-dimensional microstructures on the LED chips.

14. The method for manufacturing the backlight according to claim 13 , the providing the silica gel layer and the plurality of three-dimensional microstructures on the LED chips comprises:

providing a mask layer on the LED chips, the mask layer having a plurality of through-holes and microstructures;

forming the silica gel layer on the LED chips through the plurality of through-holes, and forming the plurality of three-dimensional microstructures on a surface of the silica gel layer and at positions corresponding to the microstructures of the mask layer;

curing the silica gel layer, on which the plurality of three-dimensional microstructures are formed; and

removing the mask layer.