CN114863829A - Miniature LED display device - Google Patents

Abstract

A micro LED display device comprising: a color conversion layer; the group of micro LEDs are attached with a color conversion layer, the micro LEDs are electrified to emit same color light, the color conversion layer converts the color light into light and emits the light, and each micro LED is provided with an N pole pad and a P pole pad; an electrical connection layer comprising: a set of cathode circuits electrically connected to the N-pole pads; a group of anode circuits electrically connected with the P pole pad; a group of driving IC, a group of conductors are arranged in the driving IC, one metal pad on the first surface of the driving IC is connected with one welding pad on the second surface of the driving IC through the conductors, and the metal pad is electrically connected with a cathode circuit or an anode circuit; and one circuit substrate is electrically connected with the bonding pads of the group of driving ICs. The circuit substrate is connected to the metal pad on the first surface part through the bonding pad on the second surface of the driving IC to conduct the conducting operation of the signal and the power supply, and the residual metal pad on the first surface of the driving IC is connected with the N pole pad and the P pole pad through a cathode circuit and an anode circuit to precisely control the light emission of the micro LED.

Description

Miniature LED display device

Technical Field

The invention relates to the field of display, in particular to a micro LED display device.

Background

Generally, a conventional LED display device is dispensed on a Substrate (Substrate) to fix a Light-Emitting Diode (LED) on the Substrate. The LED is presented as a crystal or chip, and the foregoing process is collectively referred to as a Die Bonding (Die Bonding) step.

And exposing the P electrode representing the positive electrical property and the N electrode representing the negative electrical property on the same side of the LED, and respectively covering a mass of tin material (Solder) to complete the step of crystal solidification after Flip Chip (Flip Chip). The flip chip type LED can be electrically connected with a circuit substrate through packaging steps such as cutting, die bonding and the like.

In general, the fineness of a display device is measured in terms of pixel density (Pixels Per inc., abbreviated PPI). Generally, the higher the pixel value per inch of a screen made of LEDs is, the more the number of dots representing the pixels is, and the higher the resolution of the screen is. However, the size of micro LED (micro LED) is below 100 μm, which is about 1% of the general LED size specification, and the following problems are encountered in the fabrication of the display device:

for example, millions of micro LEDs are transferred in bulk from at least one native substrate (e.g., a sapphire substrate or a gallium arsenide substrate) to a Thin Film Transistor (TFT) glass substrate or circuit substrate. Conventional machines or equipment can transfer general LEDs, but are not suitable for transferring micro LEDs with small volume. Currently, the same industry is still working on technical research and development in an attempt to overcome the bottleneck of mass transfer.

Next, the number of the micro LEDs is also large, and the number of the contacts of the circuit board is also large. In order to lay out the micro LEDs with high pixel density on the display device, not only is the circuit for splicing the wires complicated and the cost of precise control is relatively increased, but also the massive transfer of single micro LEDs is not favorable, so that the reject ratio is always high in the production process of the LED display device.

Therefore, how to solve the drawbacks of the micro LED display device becomes a problem to be solved in the present invention.

Disclosure of Invention

In view of the above, the present inventors propose a micro LED display device, and one of the main objects is to: the LED display device has the advantages that the high-precision and complicated processes of single cutting, arranging, transferring, placing and the like of LEDs in mass transfer are avoided, the LED display device can be assembled quickly, and the problem of connection of wires of the traditional display device can be solved.

The invention discloses a micro LED display device, which mainly aims to: the complexity of connecting the driving IC and the micro LED is simplified, and the manufacturing cost is saved.

The invention discloses a micro LED display device, which mainly aims to: the accuracy of the butt joint of the huge number of micro LEDs with respect to the micro electrodes (namely the N pole and the P pole) is improved, and the qualification rate of the display device is improved.

In view of the above, a first embodiment of the micro LED display device of the present invention comprises: a color conversion layer; the group of micro LEDs are attached to the color conversion layer, the micro LEDs are electrified to emit same color light, the color conversion layer converts the color light into light and emits the light, and each micro LED is provided with an N pole pad and a P pole pad; an electrical connection layer comprising: a set of cathode circuits electrically connected to the N-pole pads; a group of anode circuits electrically connected with the P pole pad; a group of driving IC, a group of conductors are arranged in the driving IC, one metal pad on the first surface of the driving IC is connected with one welding pad on the second surface of the driving IC through the conductors, and the metal pad is electrically connected with a cathode circuit or an anode circuit; and one circuit substrate is electrically connected with the bonding pads of the group of driving ICs.

Wherein, the cathode circuits and the anode circuits are criss-cross and are not connected.

Furthermore, the electrical connection layer includes: two groups of pins are arranged in a staggered way, and the pins are electrically connected with the cathode circuit and the N pole pad.

In addition, the color conversion layer is a quantum dot color filter.

The second embodiment of the micro LED display device of the present invention comprises: three groups of micro LEDs are electrified to respectively emit red light, green light and blue light, and each micro LED is provided with an N pole pad and a P pole pad; an electrical connection layer comprising: a set of cathode circuits electrically connected to the N-pole pads; a group of anode circuits electrically connected with the P pole pad; a group of driving IC, a group of conductors are arranged in the driving IC, one metal pad on the first surface of the driving IC is connected with one welding pad on the second surface of the driving IC through the conductors, and the metal pad is electrically connected with a cathode circuit or an anode circuit; and one circuit substrate is electrically connected with the bonding pads of the group of driving ICs.

Therefore, the circuit substrate is connected to the metal pad on the first surface part through the welding pad on the second surface of the driving IC to conduct the conducting operation of signals and power supply, and the residual metal pad on the first surface of the driving IC is connected with the N pole pad and the P pole pad through a cathode circuit and an anode circuit, so that the light emitting of the micro LED can be precisely controlled.

Meanwhile, the miniature LED display device can directly cut miniature LEDs with proper sizes without going through the complicated manufacturing processes of high-precision alignment, such as single cutting, mass transfer, packaging and the like of the miniature LEDs.

Secondly, the complexity of connecting the driving IC and the micro LED is simplified, so as to save the manufacturing cost. Meanwhile, the accuracy of butt joint of a huge number of micro LEDs with respect to micro electrodes (namely an N electrode and a P electrode) is improved, and the qualification rate of the display device is improved.

The features and advantages of the present invention will become more readily apparent from the following detailed description of the specific structure of at least one embodiment of the invention, when taken in conjunction with the accompanying drawings. However, the embodiments described above are not intended to limit the scope of the present invention in terms of order, shape, or size.

Drawings

Fig. 1 is a perspective view showing a specific structure of a driver IC.

Fig. 2 is also a perspective view showing the relationship between the native substrate and the light-emitting unit.

Fig. 3 is a plan view showing the relationship of the light emitting cells and the electrical connection layers.

Fig. 4 is a perspective view illustrating the driving IC electrically connected to the light emitting unit.

FIG. 5 is a side view depicting an embryonic form of a preferred embodiment of the micro LED display device.

Fig. 6 is a side view showing the completed micro LED display device.

Fig. 7 is a circuit layout diagram showing a circuit of the micro LED display device.

Fig. 8 is a plan view showing an application of the micro LED display device to a large area light emitting unit.

Description of reference numerals: 10-micro LED display device; 11-a drive IC; 12-a base; 13-a first surface; 14-a second surface; 15-a metal pad; 16-an electrical conductor; 17-a pad; 18-pin; 20-a circuit substrate; 21-power and signal lines; 22-a controller; a 24-cathode circuit; 25-anode circuit; 28-an electrical connection layer; 30-a native substrate; 31-a crystal layer; 32-epitaxial layer; 33-a light-emitting unit; 34. 35-residual materials; 36-N pole pad; 37-P pole pad; 39-micro LED; 40-color conversion layer; 41-light emitting direction; x, Y-axis.

Detailed Description

Referring to fig. 1 to 7, a preferred embodiment of a micro LED display device 10 is illustrated, which comprises a set of driving transistors, at least one circuit substrate 20, and at least one set of micro LEDs 39.

In fig. 1, a single drive crystal has a base 12 with a set of metal pads 15 disposed on a first surface 13 of the base 12. The second surface 14 of the base 12 is opposite the first surface 13. A set of bonding pads 17 is disposed on the second surface 14, the set of bonding pads 17 and the metal pads 15 are opposite to each other. A set of electrical conductors 16 is formed inside the base 12 by Through-Silicon Via (TSV) technology, each electrical conductor 16 connecting a corresponding metal pad 15 and a bonding pad 17 together to maintain an electrical connection between the two sides of the base 12, which is an Integrated Circuit (IC), so the driving crystal is also referred to as a driving IC 11.

As can be readily appreciated from fig. 2, a piece of native substrate 30 is grown with a new crystalline epitaxial layer 32 on a piece of crystalline layer 31 (e.g., sapphire), known as the epitaxial (epitoxy) technique of semiconductors. The epitaxial layer 32 is typically an LED structure, and is grown to a thickness in the crystal layer 31 by an epitaxial technique. In this embodiment, a part of the original substrate 30 is cut, and a plurality of excess materials 34 and 35 are discarded to obtain the light emitting unit 33 having an appropriate size.

As shown in fig. 3, the light emitting unit 33 is coupled to an electrical connection layer 28, and the electrical connection layer 28 includes: two sets of pins 18, a set of cathode circuits 24 and a set of anode circuits 25, the set of cathode circuits 24 and the set of anode circuits 25 are criss-cross and are not connected with each other. Each pin 18 is electrically connected to the cathode circuit 24, and displays, from one side of the light emitting unit 33: one set of pins 18 arranged from the upper left to the lower right is just staggered with the other set of pins 18 arranged from the upper right to the lower left. Therefore, the two sets of pins 18 are arranged alternately on the set of cathode circuits 24.

As for the technologies for coupling the light emitting unit 33 to the electrical connection layer 28, there are various technologies, such as: photolithography using Mask or Reticle (Reticle) is used to lay out the electrical connection layer 28. The photolithographic technique, as referred to herein, generally refers to the production or deposition of multiple layers of thin films of different materials that are stacked one on top of the other to form a precisely designed circuit.

In fig. 4, the first surface of a single driver IC 11 is electrically connected to a local pin 18, so that the driver IC 11 and the set of cathode circuits 24 are electrically connected. The first surface of the same driving IC 11 is electrically connected to the set of anode circuits 25, so that the bonding pads 17 on the second surface 14 of the driving IC 11 are electrically connected to the light emitting units 33.

The micro-LEDs 39 are grown from the crystal layer 31 to the epitaxial layer 32, so that the epitaxial layer 32 is positioned on the driving IC 11.

As shown in FIG. 5, each micro LED39 has an N-pad 36 and a P-pad 37, which are positioned on the driver IC in alignment. The N-pole pad 36 contacts the cathode circuit 24 to receive a negative current, and the P-pole pad 37 contacts the anode circuit 25 to receive a positive current. Since the bonding pads 17 are electrically connected to the circuit board 20, the light emitting unit 33, the electrical connection layer 28, the driver IC 11, and the circuit board 20 form an electrical circuit for supplying power necessary for the micro LED39 to emit light.

In the figure, the Circuit Substrate 20 is selected from one of a Printed Circuit Board (abbreviated as PCB, or Printed Wire Board, abbreviated as PWB), a Polyimide (abbreviated as PI) Board, and a Glass Substrate (Glass Substrate). The circuit board 20 is connected to at least one controller 22 via at least one power and signal line 21. The controller 22 is programmable to operate the driver IC 11 to power on or off through the electrical connection layer 28.

In fig. 6, the epitaxial layer 32 is separated from the crystal layer by Laser Lift Off (LLO) technique, and the Lift Off operation is completed so that the set of micro LEDs 39 still attach the driving IC 11 to the alignment.

In the figure, a Color conversion layer 40 is disposed on top of the set of micro LEDs 39, and the Color conversion layer 40 is a Quantum Dot Color Filter (QDCF).

During the power supply of the circuit substrate 20, the group of micro LEDs 39 emit a plurality of light beams in the light emitting direction 41 to be incident on the color conversion layer 40. The color conversion layer 40 converts light having a uniform color into three colors of red, green, and blue (RGB), and emits the three colors of light to the outside of the micro LED display device 10. The controller 22 is able to calibrate the brightness of the micro-LEDs 39 to achieve the color and brightness requirements of the display device.

In fig. 7, the cathode circuits 24 of the group are arranged in the X-axis direction, and are not connected to each other. The anode circuits 25 are arranged along the Y-axis direction and are also not connected to each other. Even if a single cathode circuit 24 energizes the N-pole pad 36 of multiple micro-LEDs 39, these micro-LEDs 39 do not emit light. Likewise, the single anode circuit 25 energizes the P-pad 37 of the plurality of micro-LEDs 39, and the micro-LEDs 39 do not emit light. Therefore, the micro LEDs 39 of the intersection of the cathode circuit 24 and the anode circuit 25 can emit light, so that the circuit layout of the entire micro LED display device facilitates current or voltage control of the individual LEDs.

As shown in fig. 8, if a plurality of light emitting units 33 are combined together, it represents that the area of the micro LED display device is large. According to the circuit layout, the light emitting units 33 arranged side by side are electrically connected to the first surfaces of the set of pedestals 12, the circuit substrate is electrically connected to the pads 17 on the second surface 14 of the set of pedestals 12, and the set of driving ICs 11 can also control the current or voltage of the single LED.

It is assumed that the combined PPI of the light emitting cells 33 is 180 × 180 and the PPI of each of the driving ICs 11 is 30 × 30. The entire micro LED display device can be operated simply and conveniently by arranging the six driving ICs 11 in a group diagonally on the large-area light emitting unit 33.

In some embodiments, the micro LED display device does not have a quantum dot color filter, but three groups of micro LEDs respectively emitting red light, green light and blue light are mounted on a driving IC, and the driving IC is electrically connected to a circuit substrate to form an electrical circuit. Of course, the color conversion layer is not important after this architecture has matured to a great extent. Therefore, the micro LED display device does not use a color conversion layer, and can save some manufacturing cost, which is also within the allowable scope of the present invention.

In summary, the micro LED display device of the present invention has several advantages, which are detailed as follows:

firstly, the miniature LED with the proper size is directly cut without going through the complicated manufacturing processes of the miniature LED, such as single cutting, mass transfer, packaging and the like which need high-precision alignment.

Secondly, the complexity of connecting the driving IC and the micro LED is simplified, so that the manufacturing cost is saved.

And thirdly, the accuracy of butt joint of a huge number of micro LEDs with respect to micro electrodes (namely an N electrode and a P electrode) is improved, and the qualification rate of the display device is improved.

The embodiments are intended to explain the principles and features of the invention and to enable others skilled in the art to understand the invention for various embodiments and with the aid of examples. However, the described embodiments are not intended to limit the scope of the invention, which is defined by the claims appended hereto, and all equivalent changes and modifications that are possible in light of the foregoing disclosure are intended to be embraced therein.

Claims (7)

1. A miniature LED display device, comprising:

a color conversion layer;

the group of micro LEDs are attached to the color conversion layer, the micro LEDs are electrified to emit same color light, the color conversion layer converts the color light into light and emits the light, and each micro LED is provided with an N pole pad and a P pole pad;

an electrical connection layer comprising: a set of cathode circuits electrically connected to the N-pole pads; a group of anode circuits electrically connected with the P pole pad;

a group of driving IC, a group of conductors are arranged in the driving IC, one metal pad on the first surface of the driving IC is connected with one welding pad on the second surface of the driving IC through the conductors, and the metal pad is electrically connected with a cathode circuit or an anode circuit; and

a circuit substrate is electrically connected to the pads of the set of driver ICs.

2. The micro LED display device of claim 1, wherein the set of cathode circuits is criss-crossed and unconnected to the set of anode circuits.

3. The micro LED display device of claim 1, wherein the electrical connection layer comprises: two groups of pins are arranged in a staggered way, and the pins are electrically connected with the cathode circuit and the N pole pad.

4. The micro LED display device of claim 1, wherein the color conversion layer is a quantum dot color filter.

5. A micro LED display device, comprising:

three groups of micro LEDs are electrified to respectively emit red light, green light and blue light, and each micro LED is provided with an N pole pad and a P pole pad;

an electrical connection layer comprising: a set of cathode circuits electrically connected to the N-pole pads; a group of anode circuits electrically connected with the P pole pad;

a group of driving IC, a group of conductors are arranged in the driving IC, one metal pad on the first surface of the driving IC is connected with one welding pad on the second surface of the driving IC through the conductors, and the metal pad is electrically connected with a cathode circuit or an anode circuit; and

a circuit substrate is electrically connected to the pads of the set of driver ICs.

6. The micro LED display device of claim 5, wherein the set of cathode circuits is criss-crossed and disconnected from the set of anode circuits.

7. The micro LED display device of claim 5, wherein the electrical connection layer comprises: two groups of pins are arranged in a staggered way, and the pins are electrically connected with the cathode circuit and the N pole pad.

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