TWI878663B - Light-emitting substrate with active elements - Google Patents

Abstract

The present invention discloses a light-emitting substrate with active elements, and the light-emitting substrate comprises a carrier, a redistribution layer, a plurality of active elements and an encapsulation layer. The redistribution layer is disposed on the carrier and comprises a plurality of circuits. The plurality of active elements each respectively have a body and a plurality of pins, and the active elements are disposed on the redistribution layer. The plurality of pins of the plurality of active elements are respectively electrically connected to the plurality of circuits of the redistribution layer. The encapsulation layer is disposed on the redistribution layer. The bodies of the plurality of active elements are disposed in the encapsulation layer.

Description

Light-emitting substrate with active components

This invention relates to a light-emitting substrate, in particular to a light-emitting substrate having active components.

The packaging method of displays with active micro-light-emitting diodes (Micro LEDs) is usually to transfer the light-emitting diodes to a thin-film transistor (TFT) backplane through mass transfer technology and assemble them into the required size on the TFT backplane. However, this transfer packaging method will produce many problems.

Since the electrodes of thin film transistors are usually made of indium tin oxide (ITO) or oxide film, and the electrodes of LEDs are usually formed by nickel-gold plating or pure gold layer. However, since the thickness of the electrodes is usually micron-level, while the thickness of the electrodes of thin film transistors is only nano-level, that is, the thickness of the LED electrodes is thicker than that of the thin film transistor electrodes. Therefore, when the two are transferred to the thin film transistor backplane, due to the difference in mechanical bonding force, the thin film transistor electrodes (pins) are prone to fracture, thereby reducing the overall bonding yield of the LED and the thin film transistor.

In addition, since the thin film transistor backplane has a relatively large area, when it has a large area, it not only makes the subsequent packaging process difficult, but also easily causes warpage problems in the structure.

Furthermore, after the production of a large-size thin-film transistor backplane is completed, if there are defects in the thin-film transistors or light-emitting diodes in the backplane, it will be more difficult to repair and test the entire large-size backplane. In addition, the repair operation on the large-size backplane needs to be further performed through repair equipment, which not only increases the difficulty of repair and reduces the yield of the product, but also increases the difficulty of manufacturing large backplane size and high unit pixel displays.

Please refer to Figure 6, which is a cross-sectional view of a known active micro-LED display structure. The current active micro-LED display structure 4 is to transfer the micro-LED 41 to the redistribution circuit layer 42, the redistribution circuit layer 42 is connected to the thin film transistor backplane 43, and then the transferred thin film transistor backplane 43 is spliced with the carrier plate 44 to assemble into the required display size. However, this splicing method not only requires the additional production of the thin film transistor backplane 43 for bonding, but also increases the production cost of the display.

Therefore, how to provide a light-emitting substrate with active components has become a topic that urgently needs to be studied.

In view of the above problems, this invention discloses a light-emitting substrate with active components, including a carrier, a redistribution circuit layer, a plurality of active components and a packaging layer. The redistribution circuit layer is disposed on the carrier and has a plurality of circuits. The plurality of active components each have a body and a plurality of pins, disposed on the redistribution circuit layer, and the plurality of pins are electrically connected to the plurality of circuits of the redistribution circuit layer. The packaging layer is disposed on the redistribution circuit layer, and the bodies of the plurality of active components are disposed in the packaging layer.

As mentioned above, before the active components are transferred to the redistribution wiring layer, the pins of the active components can be adjusted to achieve coplanar characteristics, thereby increasing the yield of the active components transferred to the redistribution wiring layer. Furthermore, by directly connecting the pins of the active components through the wiring of the redistribution wiring layer, the process steps of opening holes and connecting wiring on the redistribution wiring layer can be saved. In addition, this invention has the advantages of cutting the active components and micro-LEDs into small units, and testing them before placing them on the redistribution wiring layer, so as to improve the yield of the active components and micro-LEDs, further reduce the difficulty of subsequent repairs on large-area panels, and avoid the problem of warping, and connect the micro-LEDs and redistribution wiring layer through the method of mass transfer. The circuit layer uses each independent thin film transistor small unit or complementary metal oxide semi-conductor field effect transistor small unit to control each micro-LED respectively, thereby reducing the need for thin film transistor backplane and reducing the overall thickness, thereby simplifying the process of transferring the LED to the thin film transistor backplane and then connecting it to the carrier board, so that the light-emitting substrate with active components in this invention can be widely used in the existing micro-LED mass transfer technology.

1: Light-emitting substrate with active components

11: Active components

11A: Active components

11B: Passive components

111: Pin connection

112: Body

113: Surface

12: Adhesive layer

13: First temporary substrate

14: Packaging layer

15: Second temporary substrate

16: Re-layout the circuit layer

161: Line

162: Soldering layer

17: Carrier plate

18: Filling layer

2: Light-emitting substrate with active components

21: First carrier plate

211: Surface

22: Second carrier plate

221: Line

222: Soldering layer

23: Connection layer

3: Light-emitting substrate with active components

31: First carrier plate

32: Second carrier plate

4: Active micro-LED display structure

41: Micro LEDs

42: Re-layout the circuit layer

43: Thin film transistor backplane

44: Carrier plate

Figures 1A to 1G are step flow charts for making the first embodiment of the light-emitting substrate with active elements of the present invention; Figures 2A to 2C are step flow charts for making the second embodiment of the light-emitting substrate with active elements of the present invention; Figure 3 is a cross-sectional view of the third embodiment of the light-emitting substrate with active elements of the present invention; Figure 4 is a cross-sectional view of the fourth embodiment of the light-emitting substrate with active elements of the present invention; Figures 5A to 5C are cross-sectional views of the fifth embodiment of the light-emitting substrate with active elements of the present invention; and Figure 6 is a cross-sectional view of the structure of a known active micro-light-emitting diode display.

Please refer to FIG. 1A to FIG. 1G, which are flow charts of the first embodiment of the step of manufacturing the light-emitting substrate with active elements of the present invention. In the step of FIG. 1A, a plurality of active elements 11 are arranged on a first temporary substrate 13 having an adhesive layer 12, and the adhesive layer 12 is arranged on the first temporary substrate 13, so that the pins 111 of the plurality of active elements 11 are bonded to the adhesive layer 12. In the steps of FIG. 1B and FIG. 1C, a second temporary substrate 15 having a molding layer 14 is provided, and the molding layer 14 is arranged on the second temporary substrate 15, and the active elements 11 on the first temporary substrate 13 and the adhesive layer 12 are connected, so that the plurality of active elements 11 are buried in the molding layer 14. In the step of FIG. 1D, the first temporary substrate 13 and the adhesive layer 12 are removed to separate the active element 11 from the first temporary substrate 13 and the adhesive layer 12. In the step of FIG. 1E, the thickness of the packaging layer 14 is reduced to expose the pins 111 of the plurality of active elements 11. In the steps of FIG. 1F and FIG. 1G, the plurality of active elements 11 are docked on the carrier board 17 having the redistribution circuit layer 16, so that the pins 111 of the plurality of active elements 11 are respectively connected to the circuits 161 of the redistribution circuit layer 16, and the second temporary substrate 15 is removed to complete the light-emitting substrate 1 with active elements.

In the step of FIG. 1A , the active element 11 includes a plurality of active elements 11A and a plurality of passive elements 11B. The active element 11A is a thin film transistor or a complementary metal oxide semi-conductor field effect transistor, and the passive element is a light-emitting diode. In the diagram, the active element 11 having three pins 111 is the active element 11A, such as a thin film transistor or a complementary metal oxide semi-conductor field effect transistor, and the active element 11 having two pins 111 is the passive element 11B, such as a light-emitting diode. The light-emitting diode includes a light-emitting diode that can emit red light (R), green light (G) and blue light (B). The active element 11 is a die cut from a wafer, and is picked and placed on the adhesive layer 12 of the first temporary substrate 13 by using micro-electromechanical (MEMS) array technology or elastic mold (Elastomer) or other die transfer methods using electrostatic, Van der Waals force, and magnetic force. The adhesive layer 12 is set on the surface of the first temporary substrate 13 and has adhesiveness. The pins 111 of the active element 11 can be adhered and fixed on the first temporary substrate 13 through the adhesive layer 12. In this embodiment, the number of the plurality of active elements 11A included in the active element 11 is the same as the number of the plurality of passive elements 11B, and they correspond one to one, that is, each active element 11A corresponds to a passive element 11B connected to the control. Furthermore, by inputting high and low voltage level signals to the active element 11A, the opening and closing of the active element 11A can be controlled, and the operation of the passive element 11B can be further controlled, that is, whether the light-emitting diode emits light or not.

In the steps of FIG. 1B and FIG. 1C , the first temporary substrate 13, the adhesive layer 12 and the active components 11 are pressed onto the second temporary substrate 15 having the encapsulation layer 14, and after the encapsulation layer 14 is cured by a thermal curing reaction, the plurality of active components 11 are fixedly embedded in the encapsulation layer 14. In the embodiment of the present invention, the encapsulation layer 14 comprises an epoxy resin material. In addition, it should be noted that in the steps of Figures 1B and 1C, the first temporary substrate 13, the adhesive layer 12 and the active component 11 are pressurized from the top of the second temporary substrate 15 after being flipped 180 degrees, but this is not limited in the present invention, that is, the first temporary substrate 13, the adhesive layer 12 and the active component 11 can also be pressurized from the top of the first temporary substrate 13 downward without being flipped as shown in Figure 1A. In addition, regardless of the direction of pressurization, since in the step of FIG. 1A , the pins 111 of each active component 11 are jointly disposed on the surface of the adhesive layer 12 , therefore, in the step of pressurizing the active component 11 to the packaging layer 14 in FIG. 1B and FIG. 1C , the pins 111 of each active component 11 can have a coplanar characteristic.

In the step of FIG. 1D , the adhesive layer 12 on the first temporary substrate 13 and the pins 111 of the plurality of active components 11 can be separated by heating or irradiation, so as to facilitate the removal of the first temporary substrate 13 and the adhesive layer 12. It should be noted that after the first temporary substrate 13 and the adhesive layer 12 are separated from the packaging layer 14, the pins 111 of the active component 11 are exposed and do not protrude from the surface of the packaging layer 14, and the body 112 of the active component 11 is completely covered by the packaging layer 14.

In the step of FIG. 1E , the thickness of the packaging layer 14 is reduced by plasma etching so that the pins 111 of the active component 11 protrude from the surface of the packaging layer 14.

In the step of FIG. 1F , a carrier plate 17 is provided, and a redistribution wiring layer 16 is disposed on the carrier plate 17. The redistribution wiring layer 16 includes a plurality of wirings 161 and a welding layer 162. The welding layer 162 is disposed on the wiring 161 and corresponds to the pins 111 of the active component 11 and the welding layer 162 of the redistribution wiring layer 16. The material of the welding layer 162 includes silver glue or solder paste. The redistribution wiring layer 16 can be configured and designed according to the positions of the wirings 161 and the welding layer 162 of the redistribution wiring layer 16 connected to the plurality of active components 11. Furthermore, in the step of FIG. 1F , the pins 111 of the plurality of active components 11 are connected in alignment according to the positions of the circuits 161 and the soldering layer 162 on the surface of the redistribution circuit layer 16 , thereby reducing the process of opening holes and connecting circuits in the redistribution circuit layer 16 . In the embodiment of the present invention, the carrier board 17 includes a circuit board (PCB), a glass board or a soft board.

In the step of FIG. 1G , the light-emitting substrate 1 with active components further includes a filling layer 18 disposed between the redistribution circuit layer 16 and the packaging layer 14 to facilitate bonding of the circuit 161 of the redistribution circuit layer 16 and the pin 111 of the active component 11. For example, the filling layer 18 is an underfill or an anisotropic conductive film (ACF). When the filling layer 18 is an anisotropic conductive film, the redistribution circuit layer 16 and the packaging layer 14 can be connected through the anisotropic conductive film. In this case, the welding layer 162 can be omitted on the redistribution circuit layer 16. Furthermore, in the step of FIG. 1G, taking the active element 11 of the LED as an example, in order to increase the brightness of the LED, the thickness of the packaging layer 14 can be further reduced to expose the body of the LED. The method of reducing the packaging layer 14 includes plasma surface etching. In addition, it should be noted that in the cross-sectional views of FIG. 1F and FIG. 1G, since the cross-sectional view is only a cross-sectional position of the overall structure, the arrangement position and connection relationship of the line 161 and the welding layer 162 of the re-arranged circuit layer 16 are only for illustration and do not represent the actual circuit structure.

Please refer to Figures 2A to 2C, which are flow charts of the steps of the second embodiment of the present invention for making a light-emitting substrate with active elements. In the step of Figure 2A, a plurality of active elements 11 and a packaging layer 14 are arranged on the surface 211 of the first carrier plate 21, wherein the surfaces 113 of the plurality of active elements 11 are flat against the surface 211 of the first carrier plate 21, and the packaging layer 14 is used to package and cover the body 112 of the active element 11, and the bottom of the pin 111 of the active element 11 is exposed. In the step of FIG. 2B , a redistribution circuit layer 16 is provided on the packaging layer 14. The redistribution circuit layer 16 includes a circuit 161 and a bonding layer 162, and the circuit 161 of the redistribution circuit layer 16 is connected to the pin 111 of the active component 11. It should be noted that the pin 111 of the active component 11 is still buried in the packaging layer 14, and only the bottom of the pin 111 is exposed on the surface of the packaging layer 14 to facilitate alignment and connection with the circuit 161 of the redistribution circuit layer 16. In the step of FIG. 2C , a second carrier plate 22 having a circuit layer 221 and a soldering layer 222 is provided, and the first carrier plate 21, the packaging layer 14, the redistributed circuit layer 16 and the active element 11 are flipped up and down 180 degrees, so that the redistributed circuit layer 16 is connected and arranged on the surface of the second carrier plate 22 through a connecting layer 23, and after removing the first carrier plate 21, the light-emitting substrate 2 having the active element is completed.

In the step of FIG. 2A , the first carrier plate 21 includes a glass plate. The active element 11 includes a thin film transistor, a complementary metal oxide semi-conductor field effect transistor, and a light-emitting diode. In the diagram, the active element 11 with three pins 111 is a thin film transistor or a complementary metal oxide semi-conductor field effect transistor, and the active element 11 with two pins 111 is a light-emitting diode. The light-emitting diode includes a light-emitting diode that can emit red light (R), green light (G), and blue light (B). In addition, the encapsulation layer 14 is cured by a thermal curing reaction, and then the plurality of active elements 11 are fixedly embedded in the encapsulation layer 14.

In the step of FIG. 2B , the re-arranged wiring layer 16 is a layer-added structure. In the embodiment of the present invention, the layer-added structure is not limited to a single-layer or multi-layer wiring structure. In addition, in the step of FIG. 2B , the wiring 161 of the re-arranged wiring layer 16 is protrudingly arranged on the surface of the re-arranged wiring layer 16 , but in other embodiments, the wiring 161 can also be buried under the surface of the re-arranged wiring layer 16 , which is not limited in the present invention.

In the step of FIG. 2C , the connection layer 23 is disposed on the lower surface of the redistribution circuit layer 16 and electrically connected to the soldering layer 222 of the second carrier plate 22 and the soldering layer 162 of the redistribution circuit layer 16. In one embodiment of the present invention, the connection layer 23 is a solder ball. Furthermore, when the connection layer 23 is a solder ball, the light-emitting substrate with active components further includes a filling layer 18 disposed between the lower surface of the redistribution circuit layer 16 and the second carrier plate 22. In addition, after removing the first carrier plate 21, the surface 113 of the active component 11 is exposed to the packaging layer 14, and the body 112 of the active component 11 is surrounded by the packaging layer 14.

Please refer to Figure 3, which is a cross-sectional view of the third embodiment of the light-emitting substrate with active components of the present invention. In the embodiment of Figure 3, the connection layer 23 is anisotropic conductive glue, which is arranged between the lower surface of the redistribution circuit layer 16 and the second carrier plate 22, so as to facilitate the bonding of the redistribution circuit layer 16 and the second carrier plate 22, and electrically connect the line 221 of the second carrier plate 22 and the line 161 of the redistribution circuit layer 16. In the embodiment of the present invention, the second carrier plate 22 includes a circuit board, a glass plate or a soft board. In addition, after removing the first carrier plate 21, the surface 113 of the active component 11 is exposed to the packaging layer 14, and the body 112 of the active component 11 is covered by the packaging layer 14.

Please refer to FIG. 4, which is a cross-sectional view of the fourth embodiment of the light-emitting substrate with active elements of the present invention. In this embodiment, the light-emitting substrate 3 with active elements includes a plurality of active elements 11, a redistribution circuit layer 16 and a first carrier plate 31. The redistribution circuit layer 16 is disposed on the first carrier plate 31, and has a plurality of circuits 161 and a welding layer 162, and the welding layer 162 is respectively connected to the pins 111 of the plurality of active elements 11. The difference from the above-mentioned embodiment is that the plurality of active elements 11 are respectively and individually disposed on the redistribution circuit layer 16, that is, each active element 11 is individually disposed correspondingly according to the position configuration of the circuits 161 on the redistribution circuit layer 16.

The first carrier board 31 includes a circuit board (PCB), a glass board or a soft board. The structures of the active component 11 and the redistribution circuit layer 16 are as described in the above embodiment and will not be elaborated here.

Please refer to Figures 5A to 5C, which are the fifth embodiment step flow chart of the present invention of the light-emitting substrate with active elements. In the step of Figure 5A, the surfaces 113 of a plurality of active elements 11 are disposed on the second carrier plate 32. In the step of Figure 5B, a first carrier plate 31 with a redistribution circuit layer 16 is provided, the redistribution circuit layer 16 is disposed on the first carrier plate 31, and the second carrier plate 32 and the active element 11 are flipped up and down 180 degrees, so that the pin 111 of the active element 11 is connected and disposed on the circuit 161 of the redistribution circuit layer 16. In the step of Figure 5C, after removing the second carrier plate 32, the light-emitting substrate 3 with active elements is completed accordingly.

In an embodiment of the present invention, the second carrier plate 32 comprises a glass plate. The structures of the active element 11, the first carrier plate 31 and the redistribution circuit layer 16 are as described in the above embodiment and will not be described in detail here.

In summary, the invention can adjust the pin setting height of the active components before the active components are transferred to the redistribution wiring layer, so that the pins of each active component can achieve coplanar characteristics, thereby increasing the yield of the active components transferred to the redistribution wiring layer. Furthermore, by directly connecting the pins of each active component through the wiring of the redistribution wiring layer, it is possible to save the process steps such as opening holes and connecting wires on the redistribution wiring layer. In addition, the invention has a light-emitting substrate with active components. The active components and micro-LEDs are cut into small units, and the active components and micro-LEDs are tested before being placed on the redistribution line layer to improve the yield of the active components and micro-LEDs, further reduce the difficulty of subsequent repairs on large-area panels, and avoid the problem of warping. The micro-LEDs and redistribution lines are bonded by mass transfer. The circuit layer uses each independent thin film transistor small unit or complementary metal oxide semi-conductor field effect transistor small unit to control each micro-LED respectively, thereby achieving the purpose of reducing the thin film transistor backplane, thereby simplifying the process of transferring the LED to the thin film transistor backplane and then connecting it to the carrier plate, and reducing the overall thickness, so that the light-emitting substrate with active components of this invention can be widely used in the existing micro-LED mass transfer technology.

1: Light-emitting substrate with active components

11: Active components

111: Pin connection

14: Packaging layer

16: Re-layout the circuit layer

161: Line

162: Soldering layer

17: Carrier plate

18: Filling layer

Claims (14)

A light-emitting substrate with active components, comprising: a carrier plate; a redistribution circuit layer, disposed on the carrier plate, having a plurality of circuits; a plurality of active components, each having a body and a plurality of pins, disposed on the redistribution circuit layer, and the plurality of pins are electrically connected to the plurality of circuits of the redistribution circuit layer; and a packaging layer, disposed on the redistribution circuit layer; wherein the active component comprises a plurality of active components and a plurality of passive components, and by burying the packaging layer and reducing the thickness of the packaging layer, the plurality of pins of the plurality of active components protrude from a surface of the packaging layer. The light-emitting substrate with active elements as described in claim 1, wherein the carrier plate is a circuit board, a glass plate or a flexible board. A light-emitting substrate with active elements as described in claim 1, wherein the plurality of circuits are arranged in the redistribution circuit layer. A light-emitting substrate with an active element as described in claim 1, wherein the active element includes at least one thin film transistor or at least one complementary metal oxide semi-conductor field effect transistor, and the passive element includes a light-emitting diode. A light-emitting substrate with active elements as described in claim 4, wherein the plurality of active elements and the plurality of passive elements are connected in a one-to-one correspondence. The light-emitting substrate with active elements as described in claim 1 further includes a filling layer disposed on an upper surface of the redistribution circuit layer and between the surface of the packaging layer. A light-emitting substrate with active elements as described in claim 6, wherein the filling layer is an anisotropic conductive glue or a primer. A light-emitting substrate with an active element as described in claim 1, wherein the packaging layer is epoxy resin. A light-emitting substrate having active elements as described in claim 1, wherein the packaging layer covers the body of the plurality of active elements and exposes one surface of the plurality of active elements. A light-emitting substrate having active elements as described in claim 1, wherein the packaging layer exposes the main bodies of the plurality of active elements. A light-emitting substrate with active elements as described in claim 1, wherein the packaging layer completely covers the main body of the plurality of active elements. The light-emitting substrate with active elements as described in claim 1 further includes a connection layer disposed on a lower surface of the redistribution circuit layer, connecting the carrier board and the plurality of circuits. A light-emitting substrate with active elements as described in claim 12, wherein the connecting layer is a solder ball or anisotropic conductive paste. The light-emitting substrate with active elements as described in claim 12 further includes a filling layer disposed between the lower surface of the redistribution circuit layer and the carrier plate.

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