Disclosure of Invention
In order to overcome the defects, the invention provides a novel light-emitting device, a preparation method thereof and a backlight module, and effectively solves the problems that the existing LED lamp bead is small in light-emitting angle and needs to be provided with a lens.
The technical scheme provided by the invention is as follows:
a novel light emitting device comprising:
flip-chip LED chip;
the silica gel protective layer is arranged on the light-emitting side surface of the flip LED chip;
the light emitting layer is arranged on the surface of the silica gel protective layer on the light emitting side surface opposite to the electrode side surface in the flip LED chip, and comprises light reflection particles for reflecting part of light emitted from the light emitting side surface;
and the light reflecting layer is arranged on the side surface of the electrode of the flip LED chip and is used for reflecting the light emitted from the side surface of the electrode.
The invention also provides a preparation method of the novel light-emitting device, which comprises the following steps:
forming a light emergent layer containing reflective particles on the surface of the support film;
preparing a first silica gel protective layer on the surface of the light emergent layer;
preparing a second silica gel protective layer with viscosity on the surface of the first silica gel protective layer, wherein the viscosity of the second silica gel protective layer is more than 10000 mpa.s;
arranging a plurality of flip LED chips on the surface of the second silica gel protective layer, and pressing;
curing the second silica gel protective layer after pressing;
preparing a light reflection layer on the side surface of the electrode of the flip LED chip;
and cutting to obtain single novel light-emitting device.
The present invention also provides a backlight module, comprising:
a base plate;
a plurality of novel light emitting devices according to any one of claims 1 to 3 arranged on the surface of the base plate;
and the quantum dot optical film is fixedly arranged above the light-emitting device.
The novel light-emitting device, the preparation method thereof and the backlight module provided by the invention can at least bring the following beneficial effects:
1. set up the light-emitting layer on the light-emitting side surface relative with the electrode side surface in flip-chip LED chip, return partial light reflection that should light-emitting side surface was emergent through the side outgoing to this increases whole novel illuminator's light-emitting angle (reaches 170 °), satisfies the demand to novel illuminator light-emitting angle in the straight following formula scene of being shaded. In addition, the light emitting layer is realized in a film pasting operation mode, and the height and color point of the novel light emitting device can be accurately controlled.
2. The electrode pad is wrapped up by the light reflecting layer around, can avoid the application end in the back of accomplishing with aluminium base board paster, the loss of LED light in base plate department compares in conventional LED lamp pearl, and the backlight unit luminous flux that is formed by this novel illuminator is higher.
3. Can omit lens among this novel illuminator, save material cost and lens and paste the dress cost, make backlight unit thinner simultaneously, OD distance can reach and is less than 1mm (the OD distance of current lamp pearl is greater than 10mm), further reduces the thickness of TV complete machine.
4. The novel light-emitting device and the quantum dot optical film are matched in the backlight module, so that the color gamut of the backlight module is higher than that of an OLED, the performance of the backlight module is higher than that of the OLED, the price of the backlight module is lower than that of the OLED, and the backlight module is more energy-saving than that of the OLED.
Detailed Description
In order to more clearly illustrate the embodiment of the present invention or the technical solutions in the prior art, the following description will explain embodiments of the present invention with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
As shown in fig. 1, the structure of the novel light emitting device provided by the present invention is schematically illustrated, and as can be seen from the figure, the novel light emitting device includes: flip-chip LED chip 10; a silica gel protective layer 20 disposed on a light-emitting side surface of the flip LED chip 10; the light-emitting layer 30 is arranged on the surface of the silica gel protective layer 20 on the light-emitting side surface opposite to the electrode side surface in the flip LED chip 10, and the light-emitting layer 30 contains light-reflecting particles for reflecting part of light emitted from the light-emitting side surface; and a light reflection layer 50 arranged on the electrode side surface of the flip LED chip for reflecting the light emitted from the electrode side surface.
In the novel light-emitting device, the light-emitting layer 30 is prepared from titanium dioxide powder and silica gel in a certain mass ratio, and the mass ratio of the titanium dioxide powder to the silica gel is 0.1: 1-1: 1. For example, in one example, the mass ratio of titanium dioxide powder to silica gel is 0.2: 1; in another example, the mass ratio of titanium dioxide powder to silica gel is 0.5:1, and so on. In the light emitting layer 30, the titanium dioxide powder and the silica gel are uniformly mixed according to the required proportion, and then coated on a support film (such as a transparent PET support film) for high-temperature curing to form a light emitting layer with the thickness of 10-100 μm. In the light-emitting layer 30, because the light-reflecting particle titanium dioxide is included, part of light emitted from the light-emitting side surface opposite to the electrode side surface in the flip-chip LED chip 10 can be reflected back to exit through the side surface, so that the light-emitting angle of the whole novel light-emitting device is increased, and a lens is not required to be further mounted.
The light reflecting layer 50 is similar to the light emitting layer 30, and is designed to reflect light emitted from the side surface of the electrode (light incident on the substrate) back, so as to avoid light flux loss caused by light absorption of the substrate in the SMT mounting process (for a five-sided light emitting CSP chip, approximately 30% of light is emitted toward the substrate), so that the light reflecting layer can have the same composition as the light emitting layer 30, and can also be adjusted in proportion according to actual conditions.
The silicone protective layer 20 is provided on the other 5 side surfaces excluding the electrode side surface in the flip LED chip 10, and the silicone protective layer 20 is made of silicone. In the preparation process, the first silica gel protective layer 20 is coated on the surface of the light emitting layer 30 and is cured and molded to form a double-layer film structure comprising the light emitting layer 30 and the first silica gel protective layer, and then the second silica gel protective layer with viscosity is prepared on the surface of the first silica gel protective layer, so that the flip LED chip 10 can be pressed in the second silica gel protective layer conveniently. Here, the viscosity is specifically a state where the second silicone protective layer is not completely cured, that is, a state where solid and liquid coexist and the second silicone protective layer cannot flow, and the viscosity of the second silicone protective layer is greater than 10000 mpa.s. In order to ensure that the silica gel does not overflow to the side surface of the electrode after the light is emitted from the chip and the chip is pressed, the thickness of the first silica gel protective layer is 50-100 μm, and the thickness of the second silica gel protective layer is 100-200 μm (smaller than the thickness of the flip LED chip, generally speaking, the thickness of the flip LED chip is 150-250 μm).
In one example, the mass ratio of titanium dioxide powder to silica gel in the light emitting layer and the light reflecting layer is 0.5:1, the thickness of the light emitting layer is 50 μm, the thickness of the light reflecting layer is the same as the height of the chip electrode, and the light emitting angle diagram is shown in fig. 2, and as can be seen from the diagram, the light emitting angle reaches 170 degrees, which is obviously improved compared with the existing LED lamp bead.
The present invention also provides a method for manufacturing a novel light emitting device, as shown in fig. 3, the method for manufacturing a novel light emitting device includes the steps of:
a light-emitting layer 30 containing reflective particles is formed on the surface of the support film 60, as shown in fig. 3 (a). Specifically, titanium dioxide powder and silica gel are prepared according to the required mass ratio (the mass ratio range is 0.1: 1-1: 1) to obtain a mixture, and the preparation of slurry is completed; then, the prepared mixture is coated on a support film 60 (such as a transparent PET support film), and is cured at a high temperature to form a titanium dioxide silica gel film with a thickness of 10-100 μm, namely the light-emitting layer 30.
A first silica gel protection layer 21 is formed on the surface of the light-emitting layer 30, as shown in fig. 3 (b). Specifically, a mixture of silica gel a and silica gel B is coated on the surface of the light-emitting layer 30 and cured to form a double-layer film structure including the light-emitting layer 30 and the first silica gel protective layer 21. The first silica gel protection layer 21 has a thickness of 50 to 100 μm. The proportion of the silica gel A and the silica gel B is adjusted randomly according to actual conditions.
A second silicone protective layer 22 with viscosity is prepared on the surface of the first silicone protective layer 21, and the viscosity of the second silicone protective layer 22 is greater than 10000mpa.s, as shown in fig. 3 (c). Specifically, the mixture formed by the silica gel a and the silica gel B is coated on the surface of the first silica gel protective layer 21 and baked at a low temperature to form a second silica gel protective layer 22 with viscosity, so that the flip-chip LED chip 10 can be pressed in the second silica gel protective layer 22 in a subsequent process. The term "viscous" refers to a state in which the second silicone protective layer 22 is not completely cured, i.e., a state in which solid and liquid coexist and cannot flow, and the viscosity of the second silicone protective layer 22 is greater than 10000mpa.s and the thickness is 100 to 200 μm.
Arranging a plurality of flip LED chips 10 on the surface of the second silica gel protective layer 22, putting the flip LED chips into vacuum pressing equipment for pressing, and completely curing the second silica gel protective layer 22 after pressing. Before the lamination, the support film 60 under the light emitting layer 30 is replaced with a high temperature resistant film 70, as shown in fig. 3 (d).
A light reflecting layer 50 is formed on the electrode-side surface of the flip-chip LED chip, as shown in fig. 3 (e). Specifically, titanium dioxide powder and silica gel are prepared according to the required mass ratio (the mass ratio range is 0.1: 1-1: 1) to obtain a mixture, and then the mixture is coated on the side surface of a chip electrode and cured. Then, the semi-finished product shown in fig. 3(e) is polished and thinned by a grinding wheel or a blade until the pad of the electrode 40 (e.g., copper pillar) is exposed, and a metal layer for soldering (e.g., Ni/Au layer) is plated by electroless plating, as shown in fig. 3 (f).
The entire sheet is cut, and the high temperature film 70 is removed to obtain individual novel light emitting devices, as shown in fig. 3(g) and 3 (h).
The invention also provides a backlight module which is applied to liquid crystal display devices such as televisions and the like, and the backlight module comprises a bottom plate, a plurality of novel light-emitting devices arranged on the surface of the bottom plate and a quantum dot optical film fixedly arranged above the light-emitting devices. The number and arrangement of the novel light-emitting devices are set according to actual conditions. By need not use lens among the novel illuminator to this backlight unit is thinner, can satisfy the demand of straight following formula backlight application scene, reduces liquid crystal display device whole thickness. In addition, the backlight module is matched with a quantum dot optical film by using a novel light-emitting device, so that the color gamut of the backlight module is higher than that of an OLED, the performance of the backlight module is higher than that of the OLED, the price of the backlight module is lower than that of the OLED, and the backlight module is more energy-saving than that of the OLED.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.