Large-angle high-voltage LED device and backlight module

Abstract

The utility model relates to a wide-angle high-voltage LED device and a backlight module. The large-angle high-voltage LED device comprises a substrate and a high-voltage chip array, bonding pads which are insulated from each other are arranged on the surface of the substrate, and the high-voltage chip array is fixed on the substrate and electrically connected with the substrate; the high-voltage chip array comprises n LED chips, n is larger than or equal to 2, the LED chips are arranged at intervals, and the distance between the LED chips is smaller than or equal to 100 micrometers. According to the large-angle high-voltage LED device provided by the utility model, the plurality of LED chips are connected and tightly arranged, so that a high-voltage LED array device with uniform light emission is formed.

Description

Technical Field

[0001] The utility model relates to the field of LED devices, in particular to a large-angle high-voltage LED device and a backlight module. Background Art

[0002] High-voltage LED array devices are formed by multiple LED chips connected in series. They have higher operating voltages, can achieve higher brightness and greater power output, and can achieve brighter lighting effects. They are widely used in indoor and outdoor lighting, automotive lighting and other fields. In addition, high-voltage LED chips can also achieve clearer and longer-distance displays. When the LED chip is an LED chip, multiple high-voltage LED array devices form a backlight product, which is also widely used in display screens, billboards and other fields.

[0003] See also Figure 1 and Figure 2 , which is a top view of an existing high-voltage LED array device and a schematic diagram of the connection method between two LED chips. The high-voltage LED array device of the prior art includes a bracket cup 100, a substrate 200, an LED chipset 300 and a gold wire 400. The substrate 200 is fixed to the bottom surface of the internal space of the bracket cup 100, and a positive electrode pad 220 and a negative electrode pad 230 are arranged on the surface of the substrate 200, and an insulating layer is arranged between the positive electrode pad 220 and the negative electrode pad 230. The LED chipset 300 includes a plurality of LED chips 310, and the LED chips 310 are connected in series through the gold wire 400 and are arranged at a certain distance. The first LED chip 310 and the last LED chip 310 connected in series of the LED chipset 300 are respectively connected to the positive electrode pad 220 and the negative electrode pad 230 through the gold wire 400.

[0004] However, there is a large difference in the brightness of the light emitting center and the surrounding light of the high-voltage LED array device in the prior art, that is, there is a problem of uneven light emission. When the high-voltage LED array device is applied to a display screen as a light-emitting panel, multiple light-emitting panels form an array to form a backlight panel. The smaller the distance (OD value) between the light-emitting surface of the backlight panel and the light-mixing film of the display screen, the thinner the display screen is, but the brightness difference between the center and the surrounding of the light-emitting panel is more obvious on the display screen. When the OD value is fixed, if the number of light-emitting panels on the backlight panel is small, the picture displayed on the display screen will be unevenly bright and dark stripes will appear; if the light of the display screen is to be uniform, the number of light-emitting panels must be increased, the distance between adjacent light-emitting panels on the backlight panel must be reduced (Pitch value), and the OD:Pitch of the display screen must be set to 1:2. Therefore, when the high-voltage LED array device in the prior art is applied to the field of display screens, it will lead to the problem of a large OD:Pitch ratio. Utility Model Content

[0005] Based on this, the purpose of the utility model is to provide a large-angle high-voltage LED device.

[0006] The utility model's large-angle high-voltage LED device includes: a substrate and a high-voltage chip array, wherein mutually insulated pads are arranged on the surface of the substrate, and the high-voltage chip array is fixed on the substrate and electrically connected to the substrate; the high-voltage chip array includes n LED chips, n≥2, and the LED chips are arranged at intervals, and the spacing between the LED chips is ≤100μm. The utility model's large-angle high-voltage LED device connects and arranges multiple LED chips closely, avoiding the problem of uneven light output of the LED device caused by light leaking from the side of a single LED chip, thereby forming a high-voltage LED array device with uniform light output.

[0007] Furthermore, the positive electrode of the LED chip is conductively connected to the negative electrode of the adjacent LED chip through an electrical connection layer, thereby avoiding circuit failure caused by deformation of the connection layer during packaging.

[0008] Furthermore, the spacing between the LED chips is ≥10 μm, so as to avoid short circuit caused by too small spacing between the LED chips.

[0009] Furthermore, a semi-transmissive reflective layer is covered on the area outside the electrode surface on the top of the LED chip to further increase the side light output angle, avoid the problem of uneven light output of the LED device caused by light leakage from the side of a single LED chip, and increase the light output angle.

[0010] Furthermore, insulating grooves are formed at intervals between the LED chips, and the bottom and side surfaces of the insulating grooves are covered with a semi-transmissive reflective layer.

[0011] Furthermore, the bottom surface of the LED chip is covered with a semi-transmissive reflective layer to reduce the light emitted from the top of the LED chip.

[0012] Furthermore, the LED chips are arranged to form a high-voltage chip array matrix, which facilitates the installation of the chips and the connection with the substrate.

[0013] Furthermore, it also includes a substrate, the high-voltage chip array is fixed on the substrate by a bonding adhesive, and the area of ​​the bonding adhesive is ≤ the area of ​​the high-voltage chip array.

[0014] Furthermore, the electrical connection layers at both ends of the diagonal of the high-voltage chip array matrix are electrically connected to the substrate through bonding wires, and the bonding wires extend outward along the diagonal of the high-voltage chip array to form a curved arc, and form the highest point of the upward curved arc above the substrate where the high-voltage chip array is not set.

[0015] Furthermore, a large-angle high-voltage LED backlight module is provided, the large-angle high-voltage LED device mentioned above.

[0016] In order to better understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a top view of the structure of a high-voltage LED array device in the prior art;

[0018] Figure 2 A schematic diagram of the connection between two LED chips spaced apart in a high-voltage LED array device of the prior art;

[0019] Figure 3 This is a front view of the large-angle high-voltage LED device structure of the utility model;

[0020] Figure 4 It is a top view of the large-angle high-voltage LED device structure of the utility model;

[0021] Figure 5 A schematic diagram of the LED chip structure of the large-angle high-voltage LED device of the utility model;

[0022] Figure 6 It is a schematic diagram of a high-voltage chip array of a large-angle high-voltage LED device of the utility model;

[0023] Figure 7 It is a schematic diagram of a 2*3 matrix and a 1*6 matrix formed by arranging LED chips of a large-angle high-voltage LED device of the utility model;

[0024] Figure 8 This is a light output curve diagram of the large-angle high-voltage LED device of the utility model.

[0025] Reference numerals:

[0026] Support cup 100, substrate 200, positive electrode pad 220, negative electrode pad 230, LED chipset 300, LED chip 310, gold wire 400;

[0027] Substrate 10, high-voltage chip array 20, LED chip 22, substrate 222, first semiconductor layer 224, light-emitting layer 225, second semiconductor layer 226, transparent conductive layer 227, first electrode layer 228a, second electrode layer 228b, electrical connection layer 24, semi-transparent reflective layer 26, bracket 30, packaging glue 40. DETAILED DESCRIPTION

[0028] The technical solution of the utility model is described in detail below in conjunction with the accompanying drawings.

[0029] See also Figure 3 and Figure 4 , Figure 3 and Figure 4 The front view and top view of the large-angle high-voltage LED device of the utility model are respectively: the large-angle high-voltage LED device comprises: a substrate 10, a high-voltage chip array 20, a bracket 30 and a packaging glue 40.

[0030] The substrate 10 is made of insulating material, and has a positive electrode pad 12a and a negative electrode pad 12b which are insulated from each other on the surface.

[0031] The high-voltage chip array 20 includes n LED chips 22 (n≥2) and the chips are connected in series and arranged in a matrix. Specifically, in some embodiments, 6 LED chips 22 are included, and the voltage value of the LED chips 22 is 3V, which are arranged in a 2*3 matrix of 2 columns and 3 rows, or a 1*6 matrix of 1 column and 6 rows, forming an 18V high-voltage chip array 20.

[0032] See also Figure 5 , which is a schematic diagram of the structure of the LED chip 22. The LED chip 22 includes a substrate 222, a first semiconductor layer 224, a light-emitting layer 225, a second semiconductor layer 226, a transparent conductive layer 227, and a first electrode layer 228a and a second electrode layer 228b. The first semiconductor layer 224 covers one side of the surface of the substrate 222, so that the surface of the substrate 222 is partially exposed. The light-emitting layer 225 is located on one side of the surface of the first semiconductor layer 224, so that the upper surface of the first semiconductor layer 224 is partially exposed, and the second semiconductor layer 226 covers the light-emitting layer 225. The transparent conductive layer 227 covers the second semiconductor layer 226. The first electrode layer 228a and the second electrode layer 228b are respectively arranged on the surfaces of the first semiconductor layer 224 and the transparent conductive layer 227.

[0033] Among them, the first semiconductor layer 224 is a gallium nitride layer formed by doping into a P-type layer (hole semiconductor layer) or an N-type layer (electron semiconductor layer); when the first semiconductor layer 224 is a P-type layer, the second semiconductor layer 226 is an N-type layer; when the first semiconductor layer 224 is an N-type layer, the second semiconductor layer 226 is a P-type layer. The light-emitting layer 225 is an MQW (multi-quantum well structure layer). When the current flows from the hole semiconductor layer to the electron semiconductor layer, the electrons of the electron semiconductor layer and the holes of the hole semiconductor layer diffuse to the light-emitting layer 225, and the light-emitting layer 225 can improve the recombination efficiency of electrons and holes, promote the recombination of electrons and holes in the light-emitting layer 225, and generate energy in the form of photons when the electrons and holes recombine. The photons formed can be emitted in all directions around. The transparent conductive layer 227 is an indium tin oxide transparent conductive layer, which enables the current injected into the LED chip to diffuse quickly and evenly, improves the current injection efficiency, and improves the light output efficiency of the LED chip.

[0034] The light-emitting characteristics of the LED chip 22 are: with the center of the LED chip 22 as the light-emitting center, the light is radiated to the surrounding areas, the brightness of the light emitted in the vertical direction of the LED chip 22 is higher, and the brightness of the light radiated to the surrounding areas is lower, that is, the light emitted by a single LED chip 22 is concentrated in the vertical direction, and the brightness of the side light is lower than the brightness in the vertical direction.

[0035] When the LED chips 22 are spaced apart, the light emitted from the sides of two adjacent LED chips 22 will leak out from the gap between the chips and overlap with the light emitted from the LED chips in the vertical direction, increasing the brightness of the light in the vertical direction of the LED array. The light emitted from the surrounding of the LED array mainly comes from one of the sides of the LED chips 22 located at the edge of the high-voltage chip array 20. The light with lower brightness is significantly different from the brightness of the center of the LED array, resulting in uneven light emission. Therefore, the gaps between the multiple chips are large, and the light emitted from the sides of the chips leaks out from the gaps, resulting in uneven light emission from the high-voltage LED chips.

[0036] After repeated experiments by technicians, it was found that setting the spacing between chips within the range of ≤100μm can effectively reduce the light leakage from the chips and reduce the difference in light brightness between the center and the surrounding areas of the high-voltage LED chip.

[0037] Each LED chip 22 is spaced apart to form an insulating groove, and the spacing between the LED chips 22 is ≤40μm, preferably ≤20μm. Two adjacent LED chips 22 are connected in series through a wire, one end of the wire is connected to the second electrode layer 228b exposed by one of the LED chips 22, and the other end is connected to the first electrode layer 228a on the surface of the other LED chip 22.

[0038] Although the high-voltage LED device manufactured by the high-voltage chip array 20 can emit relatively uniform light, its manufacturing yield is not high, and some of the manufactured high-voltage LED devices emit unstable light or cannot emit light normally. The technicians further analyzed that when the spacing between the LED chips 22 is set too close, a smaller diameter wire is required to reduce the shadow formed by the light between the chips passing through the wire. However, thinner wires are easy to deform, especially when the packaging glue 40 is wrapped around the high-voltage chip array 20, resulting in poor contact of the wire or even a circuit break. Therefore, some high-voltage LED array devices emit unstable light or cannot emit light normally.

[0039] Based on the above analysis, the above high voltage LED array device is further improved: the above wires are replaced by an electrical connection layer 24. The structure of the high voltage LED array device is described below in conjunction with the accompanying drawings:

[0040] See also Figure 6 The electrical connection layer 24 covers the surface of the insulating groove between two adjacent LED chips 22. One end of the electrical connection layer 24 is connected to the first electrode layer 228a exposed by one of the LED chips 22, and the other end is connected to the second electrode layer 228b on the surface of the other LED chip 22, so that the LED chips 22 are connected to form a series circuit. The material of the electrical connection layer 24 is a metal material, such as gold, copper or alloy. It can be made by metal evaporation technology such as magnetron sputtering or electron beam evaporation.

[0041] The yield rate of the high-voltage LED device manufactured by the above-mentioned high-voltage chip array 20 is improved. However, in further sample testing, technicians found that there are still some high-voltage LED array devices that cannot emit light. The technicians tried to analyze the reasons why the LED devices do not emit light. Through many explorations, technicians found that the spacing between adjacent chips is the key factor that causes the high-voltage LED array device to fail to emit light: on the one hand, the chip spacing is too small, which can easily lead to chip contact short circuit; on the other hand, in a humid environment, water vapor is easily deposited in the insulating grooves between adjacent chips, and there is a high barrier voltage between the unit chips, which makes the conduction circuit abnormal, causing ion migration and causing the chip to short-circuit and fail. Therefore, the structure of the large-angle high-voltage LED device is further improved: the spacing between the LED chips 22 is ≥10μm, preferably ≥15μm.

[0042] Furthermore, in order to increase the light output angle of the high-voltage LED array device of the utility model, reduce the light emitted from the top of the LED device, and improve the consistency of the brightness of the top and side of the LED device, the following configuration is also included: a semi-transparent reflective layer 26 is covered on the horizontal plane of the top of the LED chip 22. The semi-transparent reflective layer 26 reflects the light emitted non-vertically from the top of the LED chip 22 to the side, reduces the light output intensity directly above the LED chip 22, improves the light output intensity from the side of the LED chip 22, and can also play an insulating and protective role. In some embodiments, a semi-transparent reflective layer 26 is also provided at the bottom of the LED chip 22, which can make a part of the light emitted by the LED chip 22 continuously reflected and refracted between the top and the bottom, and emitted from the side of the high-voltage chip array 20, further improving the light output intensity from the side of the LED chip 22. The semi-transmissive reflective layer 26 is a DBR layer (distributed Bragg reflector) and can be prepared into DBR layers of different thicknesses by selecting different materials according to the wavelength of the required high-voltage LED array device, so that the refractive index of the DBR layer meets the wavelength required by the high-voltage LED array device, and the material of the DBR layer includes one or more of silicon oxide, titanium oxide, magnesium fluoride, yttrium oxide, zinc sulfide, zirconium oxide and silicon nitride. In some embodiments, the silicon oxide film layer and the titanium oxide film layer are alternately stacked to form a periodic structure of the DBR layer using ion source assisted vacuum coating technology.

[0043] The high-voltage chip array 20 uses an electrical connection layer to arrange and connect multiple LED chips 22 at a smaller distance, reducing the light leaking from the gaps between the LED chips and emitting to the top, and achieving a large-angle luminous effect.

[0044] The technicians tested the high-voltage chip array 20 and found that although the light emitted from the top was weakened, it was still relatively bright. After further analysis, it was found that the LED chips 22 were separated by insulating grooves, and some light would leak out from the insulating grooves and be emitted from the top of the chip, resulting in brighter light emitted from the top of the LED device. Therefore, the structure of the high-angle high-voltage LED device was further improved: the DBR layer was covered on the bottom and side of the insulating groove to reduce the light emitted from the high-voltage chip array 20 to the top, so that the device emits light evenly and increases the light output angle of the LED device.

[0045] The high-voltage chip array 20 is fixed on the surface of the substrate 10, and the first LED chip 22 and the last LED chip 22 of the matrix series circuit of the high-voltage chip array 20 are respectively connected to the positive electrode pad 12a and the negative electrode pad 12b on the surface of the substrate through bonding wires, and the bonding wires are suspended above the high-voltage chip array 20 and the substrate 10. Further, in order to reduce the shielding of the light of the high-voltage chip array 20 by the bonding wires suspended on the high-voltage chip array 20, the first LED chip 22 and the last LED chip 22 in the matrix series circuit of the high-voltage chip array 20 are respectively arranged at the two ends of one of the diagonals of the high-voltage chip array 20. The distance between the corresponding electrode layer connecting the high-voltage chip array 20 and the pad of the substrate 10 is made closer, thereby shortening the required bonding wire length.

[0046] See also Figure 7 , the specific structure of setting the first LED chip 22 and the last LED chip 22 in the matrix series circuit of the high-voltage chip array 20 at the two ends of one of the diagonals of the high-voltage chip array 20 is: when the LED chips 22 are arranged in a 2*3 matrix, the electrical connection layer 24 is arranged in a "bow" shape on the 2*3 matrix, specifically, the electrical connection layer 24 between the two LED chips in each row is arranged horizontally; the electrical connection layer 24 between the LED chip in the first row and the second column and the LED chip in the second row and the second column is arranged vertically; the electrical connection layer 24 between the LED chip in the second row and the first column and the LED chip in the third row and the first column is arranged vertically. When the LED chips 22 are arranged in a 1*6 matrix, the electrical connection layer 24 is arranged in a "1" shape on the 1*6 matrix, specifically, the electrical connection layer 24 between the LED chip in each row and the LED chip in the next row is arranged vertically.

[0047] In order to further reduce the shadow formed by the bonding wire, the bonding wire extends outward along the diagonal line of the high-voltage chip array 20 to form a curved arc, and forms the highest point of the upward curved arc above the substrate 10 where the high-voltage chip array 20 is not provided, so that the shadow formed by the light emitted by the high-voltage chip array 20 due to the shielding of the bonding wire is minimized. The bonding wire is a gold wire, a copper wire or an alloy wire.

[0048] The high-voltage chip array 20 is fixed on the electrode layer on one side of the substrate 10 by a bonding adhesive. The area of ​​the bonding adhesive is ≤ the area of ​​the high-voltage chip array 20, so that the heat accumulated on the bonding adhesive of the high-voltage chip array 20 is less, ensuring a better chip heat dissipation effect; the bonding adhesive absorbs less light to the high-voltage chip array 20, so as to achieve a better light emitting effect. The bonding adhesive material can be selected from silicone resin glue, silver paste or solder paste. Preferably, a low-reflectivity silicone resin glue bonding adhesive is used to reduce the light reflected from the bottom to the top.

[0049] The bracket 30 is fixed around the edge of the substrate 10 to form a cup-shaped structure with the substrate 10, and the horizontal cross section is rectangular or square. The material of the bracket 30 is one of a thermoplastic material, a thermosetting material EMC (epoxy resin molding compound), and a ceramic substrate. Preferably, the thermoplastic material bracket used is a PCT bracket (polycyclohexylene dimethylene terephthalate resin), and its light transmittance is greater than 50%.

[0050] The encapsulation glue 40 fills the inner space of the cup-shaped structure of the bracket 30, tightly wraps the high-voltage chip array 20, and is hemispherical, with a height between 0.5mm and 1.0mm; the material of the encapsulation glue includes silicone with a refractive index greater than 1.43. The hemispherical encapsulation glue 40 can refract light to the side, thereby increasing the light intensity of the LED chip 22.

[0051] Working principle of the utility model: The distance between multiple LED chips 22 of the large-angle high-voltage LED device of the utility model is small. When a single LED chip 22 emits light, the light emitted obliquely upward from its side cannot leak out from the gap between adjacent chips, which can avoid aggravating the difference in light brightness between the top surface and the side of the high-voltage chip 10 unit. In addition, multiple LED chips 22 are connected by an electrical connection layer 24 to avoid circuit failure caused by deformation of the connection layer during packaging. In addition, setting the chip spacing ≥ 10μm can avoid short circuit problems caused by too close chip spacing. Furthermore, after the semi-transparent reflective layer 26 is set, the light emitted from the top of the light-emitting layer 124 in a non-vertical direction is reflected to the light deviating from the center normal direction, which reduces the light intensity directly above the LED chip 22 and increases the light intensity on the side of the LED chip 22, thereby achieving the effect of increasing the light angle and uniform light output at the same time.

[0052] like Figure 8 The light output angle of the large-angle high-voltage LED device of the utility model is greater than 150°.

[0053] The utility model also provides a backlight module, which is formed by the arrangement of the above-mentioned large-angle high-voltage LED device array. When the large-angle high-voltage LED device is applied to the backlight module, the OD:Pitch ratio reaches 1:3 to 1:3.5, which means that the amount of devices used in the backlight board is reduced by more than 30% while meeting the display effect of the same model. Among them, OD is the distance between the light-emitting surface of the backlight board and the light-mixing film of the display screen; Pitch is the distance between adjacent light-emitting panels (large-angle high-voltage LED devices) on the backlight board.

[0054] Compared with the prior art, the large-angle high-voltage LED device of the utility model connects multiple LED chips in series by means of an electrical connection layer, so that the chips are closely arranged and a DBR layer is set, thereby achieving the effect of large-angle light emission and uniform light output of the LED device. When applied to the backlight module, the OD:Pitch ratio is small.

[0055] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and the utility model is also intended to include these modifications and modifications.

Claims

1. A high-voltage LED device with a large angle, characterized in that: It comprises a substrate and a high-voltage chip array, wherein mutually insulated solder pads are arranged on the surface of the substrate, and the high-voltage chip array is fixed on the substrate and electrically connected to the substrate; the high-voltage chip array comprises n LED chips, n≥2, and the LED chips are arranged at intervals, and the spacing between the LED chips is ≤100μm.

2. The high-voltage LED device with a large angle according to claim 1, characterized in that: The positive electrode of the LED chip is conductively connected to the negative electrode of the adjacent LED chip via an electrical connection layer.

3. The high-voltage LED device with a large angle according to claim 2, characterized in that: The distance between the LED chips is ≥10 μm.

4. The high-voltage LED device with a large angle according to claim 3, characterized in that: The area outside the top electrode surface of the LED chip is covered with a semi-transmissive reflection layer.

5. The high-voltage LED device with a large angle according to claim 4, characterized in that: An insulating groove is formed at the interval between the adjacent LED chips, and the bottom and side surfaces of the insulating groove are covered with a semi-transmissive reflective layer.

6. The high-voltage LED device with a large angle according to claim 5, characterized in that: The bottom surface of the LED chip is covered with a semi-transmissive reflective layer.

7. The high-voltage LED device with a large angle according to claim 6, characterized in that: The n LED chips form a series circuit, and the first LED chip and the last LED chip of the high-voltage chip array series circuit are located at two ends of the diagonal line of the high-voltage chip array.

8. The high-voltage LED device with a large angle according to claim 7, characterized in that: The high-voltage chip array is connected to the substrate via bonding wires, which extend outward along the diagonal of the high-voltage chip array to form a curved arc, and form the highest point of the upward curved arc above the substrate where the high-voltage chip array is not arranged.

9. The high-voltage LED device with a large angle according to claim 8, characterized in that: The high-voltage chip array is fixed on the substrate by a bonding adhesive, and the area of ​​the bonding adhesive is less than or equal to the area of ​​the high-voltage chip array.

10. A large-angle high-voltage LED backlight module, characterized in that: It comprises a plurality of large-angle and high-voltage LED devices as described in any one of claims 1 to 9, wherein the large-angle and high-voltage LED devices are arranged in an array.

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