TW202236659A - Pixel unit with driver IC and preparation method thereof which can mass-produce pixel units by starting from a micro-dispensing step and through the procedures of mass transfer, heating and curing, photoresist forming, packaging, sputtering and etching, until a cutting step - Google Patents

Abstract

The present invention provides a preparation method, which can mass-produce pixel units by starting from a micro-dispensing step and through the procedures of mass transfer, heating and curing, photoresist forming, packaging, sputtering and etching, until a cutting step. Each pixel unit has a structure of electrode elements matched with driver IC and micro-LED. The tiny micro-LEDs occupy the smallest surface area of the display device and have a better filling rate. Moreover, the solder pads are used as coplanar electrical contact points between the micro-LEDs and the electrodes, which can be directly combined with the drive circuit of the display device to make pixel units having multiple electrical connection points and reduce the number of power distribution wires.

Description

Pixel unit with driver IC and its manufacturing method

The present invention relates to the field of image display, and particularly refers to: a pixel unit with a driving IC capable of maintaining an electrical connection with a display device.

Known display devices include: liquid crystal technology (that is, liquid crystal display panel, abbreviated as LCD) and plasma technology (that is, plasma display panel), which allow the display device to have a light-emitting panel with a large size and a long service life. However, liquid crystal display panels have problems such as power efficiency and directivity, while plasma display panels have problems such as power consumption and screen burn-in.

Alternative technologies developed on the basis of organic light-emitting diodes (Organic Light-Emitting Diode, abbreviated as OLED) have not yet achieved satisfactory results. Even OLEDs with a short lifespan can cause flickering problems in display devices, reducing the willingness of smartphones to use OLEDs for displays.

In addition, the LCD, plasma display panel, OLED and other technologies, the control circuit manufactured by thin film deposition technology is called thin-film transistor (Thin-Film Transistor, abbreviated as TFT). For example, LCD forms 5 to 9 channel regions by continuously depositing thin films of raw materials, and electrically connects components such as transistors, capacitors, and electrical circuits of the control circuit, so the cost of the control circuit manufactured by TFT technology is very expensive. At the same time, the production of large-scale active arrays by TFT technology requires large-area thin-film deposition machines or equipment, which substantially increases the cost of manufacturing and becomes a threshold for a small number of investors to operate high-cost TFT technology.

Therefore, the inventor of this case is committed to the research of light-emitting devices with low cost, high integration and good mass production rate, and has applied for patents in China No. 202010849066.3, US No. 16/999,086, and Taiwan No. 109125291, which are well documented.

However, the inventor of this case is not complacent because of this, and still continues the technical research in related fields, and invented a pixel unit manufacturing method with a driver IC. One of the main purposes is to continue the aforementioned research direction and realize that the pixel unit has a micro LED, which emits red light when it is energized. , green, blue (R, G, B) one of the three colors of light, not only has a pixel with a complete image, but also the small size of the micro-LED occupies the smallest surface area of the display device, and has a better filling rate.

One of the main purposes of the present invention is that the pad is a coplanar electrical contact point between the micro-LED and the electrode, and can be directly combined with the driving circuit of the display device.

One of the main purposes of the present invention is to use micro-LEDs to produce pixel units with multiple electrical connection points to reduce the number of distribution wires.

From the achievement of the above-mentioned purpose, the present invention performs the following steps in sequence:

Coating some adhesives on one side of the substrate;

Using the mode of micro-LEDs with electrode parts and driver ICs, a large number of electrode parts, driver ICs and micro-LEDs are transferred to the adhesive on the substrate;

Dry the adhesive to become a solid attachment part, so that the electrode parts, driver IC and micro LED are fixed on the substrate and maintain the electrical connection;

In addition to the light-emitting surface, a photoresist layer is formed around the micro-LED to prevent light from passing through;

Thermosetting plastics are used to form a transparent non-conductive layer, and the non-conductive layer combined with the substrate is used to seal the electrode parts, driver IC and micro LED;

Through sputtering, a transparent conductive film is arranged on the surface of the electrode parts, non-conductive layer, driver IC and micro LED, and the circuit layout surface inside the conductive film is electrically connected to the electrode parts and each micro LED;

By means of etching, the unused parts of the substrate are removed, and the useful parts are defined as multiple sets of electrical connection pads and multiple sets of electrical connection pads. Each set of electrical connection pads remains on the surface of the driver IC, and each set of electrical connection pads electrically connects the electrode parts to each Micro LEDs; and

The conductive film and the non-conductive layer are cut by laser means to obtain multiple pixel units with transparent shells, and the shells and conductive films are used to cover electrode parts, driver ICs and micro LEDs.

Among them, a plurality of first lines and a plurality of second lines are etched on the conductive film, and the intersecting first lines and second lines form a number of grid areas, and the laser light is guided to cut the conductive film and the non-conductive layer to obtain the size specification like a square. The shell of the grid area. In addition, the conductive film is attached to the light emitting surface of the micro LED.

Making a pixel unit according to the method includes: at least one electrode member; at least one driver IC, a second surface of the driver IC is configured with a plurality of welding pads; at least one micro LED has a first electrode terminal and a second electrode terminal. The electrode terminal, the first electrode terminal is arranged on a light-emitting surface of the micro-LED, and a photoresist layer is formed around the micro-LED, and the photoresist layer does not cover the light-emitting surface; a group of electrical connection sheets and a group of electrical connection pads, The group of electrical connection pads electrically connects the local welding pads of the driver IC to the electrode parts and the second electrode terminals of each micro-LED, and the group of electrical connection pads is electrically connected to the remaining welding pads of the driver IC; a transparent and non-conductive shell encloses the electrodes parts, drive IC and photoresist layer, so that the top surface of the electrode part, the first electrode terminal of the micro LED, the electrical connection sheet and the electrical connection pad are exposed from the shell; and, a transparent conductive film is arranged on the electrode part, the drive IC, the micro LED The surface of the LED and the shell, and a circuit layout surface inside the conductive film are electrically connected to the top surface of the electrode part and the first electrode terminal of the micro LED.

In this way, the method of the present invention produces a pixel unit equipped with a driver IC to realize a micro-LED with red, green, and blue light in the pixel unit, which not only has a pixel with a complete image, but also occupies the smallest surface area of the display device with a small size. With better filling rate.

Secondly, the welding pad is a coplanar electrical contact point between the micro-LED and the electrode, and can be directly combined with the driving circuit of the display device.

Furthermore, micro-LEDs are used to produce pixel units with multiple electrical connection points, reducing the number of distribution wires.

In order to make the purpose, features and advantages of the present invention comprehensible, one or more preferred embodiments will be described in detail below in conjunction with the attached drawings.

In Figure 1, the invention is drawn from a step of micro-dispensing 10, through mass transfer 11, heat curing 12, photoresist molding 13, encapsulation 14, sputtering 15 and etching 16, to a cutting Up to step 17, the production process of a large number of pixel units is shown. As for the process from components to finished products, a full understanding can be obtained from the specific structures in Figures 2 to 9.

In short, some adhesives 21 are coated on one side of the substrate 20 to complete the procedure of micro-dispensing 10 . Three micro-LEDs 41 emitting red, green, and blue (R, G, B) light respectively constitute an LED group 40, and a single electrode piece 22 is used in combination with a single driver IC 30 and a single LED group 40 to combine a large number of electrodes. Components 22, driver IC 30 and LED group 40 are transferred to the adhesive 21 of the substrate 20, and the mass transfer 11 procedure is performed. Then enter the step 12 of heating and curing, drying the adhesive 21 to become a solid attachment part 24, so that the electrode parts 22, the driving IC 30 and the LED group 40 are fixed on the substrate 20 and maintain the electrical connection relationship. In the photoresist forming step 13 , except for the light emitting surface 45 , a photoresist layer 44 is formed around the micro LED 41 to prevent light from passing through. Then, the non-conductive layer 23 is formed by thermosetting plastic, the non-conductive layer 23 combines with the substrate 20 and seals the electrode member 22 , the driving IC 30 and the LED group 40 , and the packaging 14 process is completed. By means of sputtering, a transparent conductive film 25 is arranged on the surface of the electrode member 22, the non-conductive layer 23, the driver IC 30 and the LED group 40, and the circuit layout surface 26 inside the conductive film 25 is electrically connected to the electrode member 22 and each micro-LED 41, Complete the sputtering 15 program. By means of etching, the unused parts of the substrate 20 are removed, and the useful parts are defined as multiple groups of electrical connection pads 50 and multiple groups of electrical connection pads 51, each group of electrical connection pads 51 remains on the surface of the driver IC 30, and each group of electrical connection pads 50 The electrode member 22 is electrically connected to each micro-LED 41 to complete the step of etching 16 . Finally, the conductive film 25 and the non-conductive layer 23 are cut by means of a laser to obtain a plurality of pixel units 60 with casings 61, and the electrode parts 22, the driver IC 30 and the LED group 40 are covered with the casings 61 and the conductive film 25, and the cutting is completed 17 step.

For the precision of the size specifications, usually a plurality of first lines 53 and a plurality of second lines 54 are etched on the conductive film 25, and the intersecting first lines 53 and second lines 54 enclose several grid areas 55 to guide the laser light The conductive film 25 and the non-conductive layer 23 are cut open to obtain the shell 61 whose size is like a grid area 55 .

Throughout the manufacturing process, the substrate 20 is a metal plate, such as a copper plate. Then, the unused part of the substrate 20 is removed by etching, and the remaining electrical connection sheet 50 and electrical connection pad 51 are naturally also copper plates.

In some embodiments, it is also within the scope of the present invention to use other metal plates with conductive properties as the substrate 20 .

As for the adhesive 21 , it can be one of silver glue and solder paste, or other solders with conductive properties. By means of baking or reflow (Reflow) soldering, the adhesive 21 becomes a solid attachment portion 24 (see FIG. 6 ), and the attachment portion 24 is conductive.

The driver IC 30 (see FIG. 4 ) is collectively referred to as a driver integrated circuit, which is a miniaturized circuit manufactured by collectively manufacturing semiconductor devices and passive components. Therefore, the driver IC 30 is also called a microcircuit (Microcircuit), a microchip (Microchip), or a chip (chip). The top surface of the driver IC 30 is defined as a first surface 31 for the conductive film 25 to be formed on the first surface 31 of the driver IC 30 (see FIG. 6 ). The bottom surface of the driver IC 30 is regarded as a second surface 32 , and a plurality of solder pads 33 are arranged on the second surface 32 of the driver IC 30 , and the solder pads 33 are connected to the substrate 20 through the attaching portion 24 . After the substrate 20 is etched, the remaining electrical connection piece 50 and electrical connection pad 51 (see FIG. 9 ) can naturally be connected to the circuit of the driver IC 30 (see FIG. 6 ) through the pad 33 .

The micro-LED 41 is a light-emitting diode (Light-Emitting Diode, abbreviated as LED), and its tiny volume is about 1/100 of the volume of a general LED, and it is usually transported to the target by mass transfer. Mass transfer is not the technical core of this case, so it will not be described in detail.

The micro LED 41 is a semiconductor, and the semiconductor has a first electrode terminal 42 and a second electrode terminal 43 . The first electrode terminal 42 is electrically connected to the electrode member 22 through the circuit layout surface 26 of the conductive film 25 (see FIG. 10 ), and the second electrode terminal 43 is connected to the driver IC 30 through the attachment part 24 and the electrical connection sheet 50. (see Figure 10) connected to the circuit.

The positive power is supplied to the top surface of the electrode part 22 and the first electrode terminal 42 by the circuit layout surface 26 of the conductive film 25, and the negative power is transmitted to the electrode part through the electrical connection piece 50, the electrical connection pad 51 and the attachment part 24 (see Figure 10). 22 bottom surface, the welding pad 33 of the driving IC 30 (see FIG. 6 ) and the second electrode terminal 43. Therefore, the first electrode terminal 42 of the micro LED 41 is positively charged, and the second electrode terminal 43 is negatively charged.

In this embodiment, the thermosetting plastic has non-conductive properties, such as artificial resin (Epoxy Resin), epoxy resin (Epoxy) and the like. The thermosetting plastic becomes a solid non-conductive layer 23 which is transparent. Therefore, the casing 61 is transparent and non-conductive, which does not prevent the micro LED 41 from emitting light to the outside.

The composition of the conductive film 25 includes but not limited to: indium tin oxide (ITO) or tin-doped indium oxide. The indium tin oxide is a mixture of indium (III group) oxide (In ₂ O ₃ ) and tin (IV group) oxide (SnO ₂ ), which is usually colorless and transparent after being sputtered into a thin film state. Therefore, the conductive film 25 is transparent.

The sputtering (Sputter Deposition∕Coating), also known as sputtering (Sputtering), generally refers to the high-energy ions of the plasma hitting the atoms of the solid target (Target) or source (Source), and the atoms leave the solid and enter the gas. physical process. According to the knowledge of electronics or the experience of technicians, sputtering is classified as one of the vapor deposition techniques.

In addition, the photoresist is arranged on the four sides of the micro-LED 41 through the coating equipment, and after being irradiated by light of a certain wavelength (such as ultraviolet light), it becomes a solid photoresist layer 44 and adheres to the surrounding of the micro-LED 41 . Therefore, the housing 61 indirectly covers the micro LED 41 through the photoresist layer 44 .

In some embodiments, the material of the photoresist layer 44 is black resin, such as polyphtalamide (Polyphtalamide, also known as PPA resin) and Epoxy Mold Compound (abbreviated as EMC) containing black carbon. One with black silicon.

After electrification, the micro-LED 41 emits red, green or blue light, and the light beam cannot pass through the electrical connection sheet 50, and the photoresist layer 44 absorbs light of all colors to limit the light incident of the micro-LED 41 to the transparent shell 61, and passes through the transparent conductive The film 25 is refracted to the outside, avoiding the disadvantage of color light mixing in the LED group 40 . Therefore, the side of the micro-LED 41 facing the conductive film 25 is regarded as the light emitting surface 45 (see FIG. 6 ), and the required first electrode terminal 42 is provided on the light emitting surface 45 .

As shown in Figures 4, 9, and 10, the pixel unit 60 produced by the aforementioned method includes: an electrode member 22; a driver IC 30 has a plurality of welding pads 33, and the welding pads 33 are arranged on a second surface of the driver IC 30 32; an LED group 40 is composed of three miniature LEDs 41 that emit red, green and blue light respectively, and the miniature LED 41 has a first electrode terminal 42 and a second electrode terminal 43, and the first electrode terminal 42 is arranged on the miniature A light-emitting surface 45 of the LED 41, a photoresist layer 44 is formed around each micro-LED 41, and the photoresist layer 44 does not cover the light-emitting surface 45; a group of electrical connection sheets 50 and a group of electrical connection pads 51, the group The electrical connection pad 50 makes the local welding pad 33 of the driver IC 30 electrically connect the electrode member 22 and the second electrode terminal 43 of each micro-LED 41, and the group of electrical connection pads 51 is electrically connected to the remaining welding pads 33 of the driver IC 30; transparent and non-toxic A conductive housing 61 encloses the electrode member 22, the drive IC 30 and the photoresist layer 44, so that the top surface of the electrode member 22, the first electrode terminal 42 of the micro-LED 41, the electrical connection sheet 50 and the electrical connection pad 51 are exposed from the housing 61; and, a conductive film 25 is transparent, and it is arranged on the surface of the electrode member 22, the driver IC 30, the LED group 40 and the housing 61, and a circuit layout surface 26 inside the conductive film 25 is electrically connected to the electrode member 22 top surface and the first electrode terminal 42 of each micro LED 41 .

In use, the pixel unit 60 is mounted on a display device (not shown). A simple circuit (not shown) of the display device determines the power supply direction, and controls the LED group 40 to emit one of red, green, and blue (R, G, B) lights, or white light mixed with red, green, and blue colors.

In this way, the pixel unit produced by the method has the following advantages:

1. Realize micro-LEDs with red, green, and blue light in the pixel unit. Not only do they have pixels with complete images, but the tiny micro-LEDs occupy the smallest surface area of the display device and have a better filling rate.

2. The welding pad is a coplanar electrical contact point between the micro-LED and the electrode, and can be directly combined with the driving circuit of the display device.

3. Use micro-LEDs to produce pixel units with multiple electrical connection points, reducing the number of distribution wires.

10: Micro dispensing 11: Mass transfer 12: Heat curing 13: Photoresist forming 14: Encapsulation 15: Sputtering 16: Etching 17: cutting 20: Substrate 21: Subsequent objects 22: electrode parts 23: Non-conductive layer 24: Attachment Department 25: Conductive film 26: Circuit layout surface 30: Driver IC 31: first surface 32: second surface 33: welding pad 40:LED group 41: Micro LED 42: first electrode terminal 43: Second electrode terminal 44: photoresist layer 45: Luminous surface 50: Electrical connection piece 51: Electrical connection pad 53: The first texture 54: Second texture 55: grid area 60: pixel unit 61: Shell

Fig. 1 draws the process flow of the present invention to make the pixel unit. Figures 2 to 9 show the specific structure from components to finished products in the process. Figure 10 shows the internal structure of the pixel unit in a cutaway view.

10: Micro dispensing

11: Mass transfer

12: Heat curing

13: Photoresist forming

14: Encapsulation

15: Sputtering

16: Etching

17: cutting

Claims (10)

A pixel unit comprising: at least one electrode member (22); At least one driver IC (30), a second surface (32) of the driver IC (30) is provided with a plurality of welding pads (33); At least one micro LED (41) has a first electrode terminal (42) and a second electrode terminal (43), the first electrode terminal (42) is set on a light emitting surface (45) of the micro LED (41), the A photoresist layer (44) is formed around the micro LED (41), and the photoresist layer (44) does not shield the light-emitting surface (45); A set of electrical connection pieces (50) and a set of electrical connection pads (51), the set of electrical connection pieces (50) make the local welding pads (33) of the drive IC (30) electrically connect the electrode parts (22) and the micro LED ( 41), the second electrode terminal (43), the group of electrical connection pads (51) is electrically connected to the rest of the pads (33) of the driver IC (30); A transparent and non-conductive shell (61) encloses the electrode part (22), the driver IC (30) and the photoresist layer (44), so that the top surface of the electrode part (22), the first electrode of the micro LED (41) The terminal (42), the electrical connection piece (50) and the electrical connection pad (51) are exposed from the housing (61); and A transparent conductive film (25) is arranged on the surface of the electrode member (22), driver IC (30), micro LED (41) and casing (61), and a circuit layout surface (26) inside the conductive film (25) is electrically The top surface of the electrode member (22) is connected with the first electrode terminal (42) of the micro LED (41). The pixel unit according to claim 1, wherein the micro LED (41) emits red light, green light or blue light when powered on. The pixel unit according to claim 1, wherein the electrical connection sheet (50) and the electrical connection pad (51) are metal plates. The pixel unit according to claim 2, wherein the metal plate is a copper plate. A method for manufacturing a pixel unit with a driver IC, manufacturing the pixel unit described in Claim 1: Coating some adhesives (21) on one side of the substrate (20); Using the mode of micro-LED (41) with electrode part (22) and driver IC (30), transfer a large number of electrode parts (22), driver IC (30) and micro-LED (41) to the bonding object of the substrate (20) (21) on; Dry the adhesive (21) to become a solid attachment part (24), so that the electrode part (22), the driver IC (30) and the micro LED (41) are fixed on the substrate (20) and maintain an electrical connection; In addition to the light-emitting surface (45), a photoresist layer (44) is formed around the micro-LED (41) to prevent light from passing through; A transparent non-conductive layer (23) is formed of thermosetting plastic, and the non-conductive layer (23) is combined with the substrate (20) to seal the electrode part (22), the driving IC (30) and the micro LED (41); By means of sputtering, a transparent conductive film (25) is arranged on the surface of the electrode member (22), the non-conductive layer (23), the driver IC (30) and the micro LED (41), and the circuit layout surface inside the conductive film (25) (26) electrically connecting the electrode piece (22) and each micro-LED (41); By means of etching, the unused part of the substrate (20) is removed, and the useful parts are defined as multiple sets of electrical connection pads (50) and multiple sets of electrical connection pads (51), each set of electrical connection pads (51) is reserved in the driver IC ( 30) On the surface, each group of electrical connecting pieces (50) enables the electrode member (22) to be electrically connected to each micro LED (41); and Cutting the conductive film (25) and the non-conductive layer (23) by means of a laser to obtain a plurality of pixel units (60) with transparent shells (61), and covering the electrode parts with the shells (61) and the conductive film (25) (22), driver IC (30) and micro LED (41). The manufacturing method of a pixel unit with a driving IC as described in Claim 4, wherein a plurality of first lines (53) and a plurality of second lines (54) are etched on the conductive film (25), and the intersecting first lines (53) and The second lines (54) enclose several grid areas (55), guide the laser light to cut the conductive film (25) and the non-conductive layer (23), and obtain the shell (61) whose size is similar to the grid area (55). The method for manufacturing a pixel unit with a driver IC as claimed in claim 4, wherein the adhesive ( 21 ) is made into a conductive attachment portion ( 24 ) by means of baking or reflow soldering. The manufacturing method of a pixel unit with a driver IC as described in claim 6, wherein the plurality of welding pads (33) of the driver IC (30) are respectively combined with the electrical connection piece (50) or the electrical connection pad through the attachment part (24) (51). The manufacturing method of a pixel unit with a driving IC as described in Claim 6, wherein the first electrode terminal (42) of the micro LED (41) is electrically connected to the electrode member (22) via the circuit layout surface (26), and the micro LED (41 ) of the second electrode terminal (43) is electrically connected to the driving IC (30) through the attachment part (24) and the electrical connection sheet (50). The method for manufacturing a pixel unit with a driver IC as claimed in item 4, wherein the conductive film (25) is attached to the light emitting surface (45) of the micro LED (41).

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