CN114497103B

CN114497103B - A modular display module, its fabrication method, and a display device.

Info

Publication number: CN114497103B
Application number: CN202011157264.XA
Authority: CN
Inventors: 陈启燊; 秦快; 郭恒; 谢宗贤; 欧阳小波; 张雪
Original assignee: Foshan NationStar Optoelectronics Co Ltd
Current assignee: Foshan NationStar Optoelectronics Co Ltd
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2025-11-04
Anticipated expiration: 2040-10-26
Also published as: CN114497103A

Abstract

This invention discloses a splicable display module, its fabrication method, and a display device. The display module includes a light-transmitting carrier substrate, a circuit board, a driving module, and multiple LED light-emitting chips. By separately placing the LED light-emitting chips and the driving module on opposite sides of the circuit board, there is no need to designate an area for fixing the driving module on the side of the circuit board where the LED light-emitting chips are located. That is, there is no area without LED light-emitting chips at the edge of this side. Consequently, in the spliced display screen, there is no area without LED light-emitting chips at the splicing seam between two spliced LED display modules, thus reducing the pixel pitch at the splicing seam, improving the display screen resolution, and optimizing the display effect. By pre-transferring the LED light-emitting chips onto a die-bonding structure on the carrier substrate, and then bonding the carrier substrate carrying the LED light-emitting chips to the circuit board, the efficiency and positional accuracy of fixing the LED light-emitting chips to the circuit board are improved.

Description

Display module capable of being spliced, preparation method and display device

Technical Field

The invention relates to the technical field of LED display, in particular to a display module capable of being spliced, a preparation method and a display device.

Background

The LED display screen is a flat panel display, which is formed by splicing small LED display modules and is used for displaying various information such as characters, images, videos, video signals and the like. Because the LED display screen has good area ductility, the LED display screen is often applied to the fields of advertising and the like which need large-size display screens.

However, as the user's resolution increases, this requires smaller and smaller spacing between pixels in the display. In the existing LED display screen, the problem that the splicing seams are too large exists at the splicing positions of mutually spliced LED modules, so that the pixel spacing of the local area at the splicing seams is too large, and the overall display effect of the display screen is affected.

Disclosure of Invention

The embodiment of the invention provides a display module capable of being spliced, a preparation method and a display device, which can reduce the pixel spacing at a splice joint when the display module is spliced and improve the resolution of a display screen.

In a first aspect, an embodiment of the present invention provides a display module capable of being spliced, including a light-transmitting carrier substrate, a circuit board, a driving module, and a plurality of LED light emitting chips;

The circuit board comprises a first bonding pad layer, a second bonding pad layer and at least one layer of circuit layer, wherein the first bonding pad layer and the second bonding pad layer are oppositely arranged, the at least one layer of circuit layer is positioned between the first bonding pad layer and the second bonding pad layer, an insulating layer is arranged between two adjacent layers in the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer, and the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer are electrically connected through a conductive via hole penetrating through the insulating layer;

the LED luminous wafer is arranged on the first bonding pad layer and is electrically connected with the first bonding pad layer, and the driving module is arranged on the second bonding pad layer and is electrically connected with the second bonding pad layer;

The carrier substrate is provided with a light-transmitting die bonding structure for fixing the LED light-emitting wafer, and the LED light-emitting wafer is fixed on the die bonding structure.

Optionally, the die bonding structure includes a positioning groove formed by a protrusion disposed on the carrier substrate, and the LED light emitting chip is fixed in the positioning groove.

Optionally, the LED light emitting wafer is a vertical wafer, the die bonding structure further includes a die bonding pad formed on the carrier substrate, and the bump is disposed on at least one edge of two opposite sides of the die bonding pad;

The first bonding pad layer comprises a plurality of first bonding pads and a plurality of second bonding pads, the first electrode of the vertical wafer is electrically connected with the first bonding pad corresponding to the vertical wafer, the die bonding pad is used as the second electrode of the vertical wafer, and the die bonding pad is electrically connected with the second bonding pad corresponding to the vertical wafer.

Optionally, the bump is a conductive bump, an anisotropic conductive adhesive is disposed between the circuit board and the carrier substrate, the first electrode of the vertical wafer is electrically connected to the first pad through the anisotropic conductive adhesive, and the bump is electrically connected to the second pad through the anisotropic conductive adhesive.

Optionally, the vertical wafer includes a first electrode, a conductive layer, a distributed bragg reflection layer, a P-type layer, a light emitting layer, and an N-type layer stacked in sequence.

Optionally, the side wall of the vertical wafer is provided with an insulating protection layer.

Optionally, the circuit board sequentially includes a first pad layer, a first insulating layer, a first circuit layer, a second insulating layer, a second circuit layer, a third insulating layer and a second pad layer;

The first insulating layer is close to the surface of the carrier substrate, the area outside the bonding pad is coated with an ink layer, or the area outside the die bonding structure is coated with an ink layer on the surface of the carrier substrate close to the circuit board.

Optionally, the insulating layer is glass, and the circuit in the circuit layer is a nano silver wire, a carbon nano tube, an ITO nano wire or a zinc oxide nano wire.

Optionally, the aperture of the conductive via is in the range of 10 μm to 15 μm.

In a second aspect, an embodiment of the present invention further provides a method for manufacturing a display module capable of being spliced, where the method is characterized by including:

Providing a circuit board, wherein the circuit board comprises a first bonding pad layer and a second bonding pad layer which are oppositely arranged, and at least one layer of circuit layer positioned between the first bonding pad layer and the second bonding pad layer, an insulating layer is arranged between two adjacent layers in the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer, and the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer are electrically connected through a conductive via penetrating through the insulating layer;

Providing a light-transmitting carrier substrate;

Forming a light-transmitting die bonding structure for fixing the LED luminous wafer on the carrier substrate;

fixing the LED luminous wafer on the die bonding structure on the carrier substrate;

Pressing the carrier substrate and the circuit board to electrically connect the LED luminous wafer and the first bonding pad layer;

And fixing the driving module on the second bonding pad layer, wherein the driving module is electrically connected with the second bonding pad layer.

Optionally, the LED light emitting wafer is a vertical wafer, and a light-transmitting die bonding structure for fixing the LED light emitting wafer is formed on the carrier substrate, including:

Forming a plurality of light-transmitting die bonding pads on the carrier substrate;

And forming conductive bulges on the edges of at least one opposite side of the die bonding pad, wherein the conductive bulges form positioning grooves.

Optionally, forming conductive bumps on edges of at least one opposite side of the die bond pad, including:

And forming the conductive bumps on at least one edge of two opposite sides of the die bonding pad in a printing mode.

Optionally, the first pad layer includes a plurality of first pads and a plurality of second pads, and the laminating the carrier substrate and the circuit board includes:

coating anisotropic conductive adhesive on one side of the carrier substrate, on which the die bonding pad is arranged, and/or on one side of the circuit board, on which the first pad layer is arranged;

And pressing the carrier substrate and the circuit board so that the first electrode of the vertical wafer is electrically connected with the first bonding pad corresponding to the vertical wafer through the anisotropic conductive adhesive, and the bump is electrically connected with the second bonding pad corresponding to the vertical wafer through the anisotropic conductive adhesive.

In a third aspect, an embodiment of the present invention further provides a display apparatus, including a display module capable of being spliced according to the first aspect of the present invention.

The display module capable of being spliced comprises a light-transmitting carrier substrate, a circuit board, a driving module and a plurality of LED luminous wafers, wherein the circuit board comprises a first bonding pad layer and a second bonding pad layer which are oppositely arranged, at least one layer of circuit layer is arranged between the first bonding pad layer and the second bonding pad layer, an insulating layer is arranged between two adjacent layers in the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer, the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer are electrically connected through conductive through holes penetrating through the insulating layer, the LED luminous wafers are arranged on the first bonding pad layer and are electrically connected with the first bonding pad layer, and the driving module is arranged on the second bonding pad layer and is electrically connected with the second bonding pad layer. Through setting up LED luminescent wafer and drive module in the both sides that the circuit board is relative respectively, like this, be provided with the one side of LED luminescent wafer on the circuit board, need not to set up the region that is used for fixed drive module, the edge of this side does not have the region that does not have LED luminescent wafer, and then in the display screen that the concatenation formed, splice seam department between two LED display modules of mutual concatenation does not have the region that does not have LED luminescent wafer, and then reduced the pixel interval of splice seam department, improved the resolution ratio of display screen, optimized the display effect. The carrier substrate is provided with the light-transmitting die bonding structure for fixing the LED luminous wafer, the LED luminous wafer is transferred onto the die bonding structure on the carrier substrate in advance, and then the carrier substrate bearing the LED luminous wafer is pressed and attached with the circuit board, so that the efficiency and the position accuracy of fixing the LED luminous wafer on the circuit board are improved.

Drawings

The invention is described in further detail below with reference to the drawings and examples.

Fig. 1 is a schematic structural diagram of a display module capable of being spliced according to a first embodiment of the present invention;

fig. 2 is a schematic structural diagram of a display module capable of being spliced according to a second embodiment of the present invention;

FIG. 3 is an enlarged view of area A of FIG. 2;

FIG. 4 is a schematic view of a vertical wafer structure according to an embodiment of the present invention;

Fig. 5 is a schematic flow chart of a method for manufacturing a display module capable of being spliced according to a third embodiment of the present invention;

fig. 6 is a schematic flow chart of a method for manufacturing a display module capable of being spliced according to a fourth embodiment of the present invention;

Fig. 7 is a schematic structural diagram of a circuit board according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a die bond pad formed on a carrier substrate according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of forming conductive bumps on a die bond pad according to an embodiment of the present invention;

FIG. 10 is a top view of the conductive bump of FIG. 9;

FIG. 11 is a schematic diagram of transferring a vertical wafer into a positioning slot according to an embodiment of the present invention;

Fig. 12 is a schematic view of an anisotropic conductive paste coated on a side of a carrier substrate provided with a die bonding pad according to an embodiment of the present invention;

fig. 13 is a schematic diagram of laminating a carrier substrate and a circuit board according to an embodiment of the present invention;

fig. 14 is a schematic diagram of fixing a driving module on a second pad layer according to an embodiment of the present invention.

Detailed Description

In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.

In the description of the present invention, unless explicitly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may, for example, be fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for providing a special meaning.

As described above, in the existing tiled display screen, the stitching seam is too large at the stitching position, so that the pixel pitch of the local area at the stitching seam is too large, and the overall display effect of the display screen is affected. The inventor has found that the existing LED display module generally has the LED light emitting die and the driving module disposed on the same side of the circuit board, such that there is a region for fixing the driving module on the side of the circuit board, and the region has no LED light emitting die. In order to facilitate the splicing, the edge of the circuit board is usually arranged in the area, so that when the display screen is formed by splicing, an area without an LED luminous wafer exists at the splicing joint between two mutually spliced LED display modules, and the pixel spacing of a local area at the splicing joint is too large, so that the overall display effect of the display screen is affected.

Example 1

In view of the above problems, fig. 1 is a schematic structural diagram of a display module capable of being spliced according to the first embodiment of the present invention, and as shown in fig. 1, the display module capable of being spliced includes a circuit board 110, a driving module 120, a plurality of LED light emitting chips 130 and a light-transmitting carrier substrate 140.

The circuit board 110 includes a first pad layer and a second pad layer disposed opposite to each other, and at least one circuit layer disposed between the first pad layer and the second pad layer, wherein an insulating layer is disposed between two adjacent layers of the first pad layer, the second pad layer and the at least one circuit layer. In the embodiment of the present invention, the number of the circuit layers is not limited, and may be specifically set according to the complexity of the circuit, for example, the more complex the circuit is, the more the number of the circuit layers can be. Illustratively, in one embodiment of the present invention, the wiring board 110 includes a first pad layer 111, a first insulating layer 112, a first wiring layer 113, a second insulating layer 114, a second wiring layer 115, a third insulating layer 116, and a second pad layer 117, which are sequentially stacked.

The LED light emitting chip 130 is disposed on the first pad layer 111 and electrically connected to the first pad layer 111, and the driving module 120 is disposed on the second pad layer 117 and electrically connected to the second pad layer 117. The first pad layer 111, the second pad layer 117, the first line layer 113 and the second line layer 115 are electrically connected through conductive vias 118 penetrating through the insulating layer, thereby realizing that the driving module 120 is electrically connected with the LED light emitting chip 130, so that the LED light emitting chip 130 can emit light in response to a driving signal emitted from the driving module 120. Specifically, the driving module 120 may include components such as resistors, capacitors, memories, etc., which are not limited herein.

Specifically, in the above embodiment, the conductive via 118 is a hole penetrating through the insulating layer, and the inner wall of the hole is provided with a conductive material, so that the two layers connected by the conductive via 118 are conducted. The conductive via 118 may connect two adjacent layers of the first pad layer 111, the second pad layer 117, the first line layer 113, and the second line layer 115, or may connect two non-adjacent layers of the first pad layer 111, the second pad layer 117, the first line layer 113, and the second line layer 115, which is not limited herein. It should be noted that the locations and numbers of the conductive vias 118 in the above embodiments are exemplary illustrations of embodiments of the present invention and are not limiting. In other embodiments of the present invention, the location and number of conductive vias 118 may vary accordingly depending on the circuit design requirements.

Through setting up LED luminescent wafer 130 and drive module 120 respectively in the opposite both sides of circuit board 110, like this, be provided with the one side of LED luminescent wafer 130 on circuit board 110, need not to set up the region that is used for fixed drive module 120, the edge of this side does not have the region that does not have LED luminescent wafer 130, and then in the display screen that the concatenation formed, the splice seam department between two LED display modules of mutual concatenation does not have the region that does not have LED luminescent wafer 130, and then reduced the pixel interval of splice seam department, improved the resolution of display screen, optimized the display effect.

In addition, the first pad layer 111, the second pad layer 117, the first line layer 113 and the second line layer 115 are electrically connected through the conductive via 118 penetrating through the insulating layer, and no wiring from the side wall of the line board 110 is required, so that the problem that the side wall wiring is easy to break due to bending of the side wall wiring is avoided.

The carrier substrate 140 may be transparent glass or polyimide, the carrier substrate 140 is provided with a transparent die bonding structure 141 for fixing the LED light emitting wafer 130, and the LED light emitting wafer 130 is fixed on the die bonding structure 141. Specifically, the die bonding structure 141 may be a limiting groove with a limiting effect or an adsorption pad with an adsorption effect, which is used for capturing the LED light emitting wafer 130 in the process of transferring the LED light emitting wafer 130 onto the carrier substrate 140, so that the LED light emitting wafer 130 is fixed on the die bonding structure 141.

The LED lighting chip 130 may be a Mini-LED or a Micro-LED, and since the LED lighting chip 130 is small in size, if the LED lighting chip 130 is fixed to the circuit board 110 one by one, the fixing efficiency will be very low. Therefore, in the embodiment of the present invention, the LED light emitting wafer 130 may be first transferred onto the carrier substrate 140 by a mass transfer manner, so that the LED light emitting wafer 130 is fixed on the die bonding structure 141. Then, the carrier substrate 140 carrying the LED light emitting chip 130 is bonded with the circuit board 110, so that the LED light emitting chip 130 is electrically connected with the first pad layer 111 on the circuit board 110, and further the fixing efficiency and the position accuracy of the LED light emitting chip 130 are improved. Light emitted from the LED light emitting die 130 exits through the light transmissive carrier substrate 140.

In the above-described embodiments, the type of the LED light emitting wafer is not limited, and may be a front-mounted wafer, a flip-chip, or a vertical wafer. The two electrodes of the front-mounted wafer are positioned on the light-emitting surface of the LED light-emitting wafer, the two electrodes of the flip-chip are positioned on the backlight surface opposite to the light-emitting surface of the LED light-emitting wafer, and the two electrodes of the vertical wafer are respectively positioned on the light-emitting surface and the backlight surface of the LED light-emitting wafer.

It should be noted that, the circuit board in the embodiment of the present invention is not limited to the printed circuit board (Printed Circuit Board, PCB) in the general sense, and may also include a glass substrate on which a circuit is printed, printed or etched on a glass or polyimide substrate in order to further improve resolution and reduce line width and line spacing, which is not limited herein.

The display module capable of being spliced comprises a light-transmitting carrier substrate, a circuit board, a driving module and a plurality of LED luminous wafers, wherein the circuit board comprises a first bonding pad layer and a second bonding pad layer which are oppositely arranged, at least one layer of circuit layer is arranged between the first bonding pad layer and the second bonding pad layer, an insulating layer is arranged between two adjacent layers in the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer, the first bonding pad layer, the second bonding pad layer and the at least one layer of circuit layer are electrically connected through conductive through holes penetrating through the insulating layer, the LED luminous wafers are arranged on the first bonding pad layer and are electrically connected with the first bonding pad layer, and the driving module is arranged on the second bonding pad layer and is electrically connected with the second bonding pad layer. The carrier substrate is provided with a light-transmitting die bonding structure for fixing the LED light-emitting wafer, and the LED light-emitting wafer is fixed on the die bonding structure. Through setting up LED luminescent wafer and drive module in the both sides that the circuit board is relative respectively, like this, be provided with the one side of LED luminescent wafer on the circuit board, need not to set up the region that is used for fixed drive module, the edge of this side does not have the region that does not have LED luminescent wafer, and then in the display screen that the concatenation formed, splice seam department between two LED display modules of mutual concatenation does not have the region that does not have LED luminescent wafer, and then reduced the pixel interval of splice seam department, improved the resolution ratio of display screen, optimized the display effect. In addition, the efficiency and the position accuracy of fixing the LED light-emitting wafer on the circuit board are improved by transferring the LED light-emitting wafer onto the die bonding structure on the carrier substrate in advance and then bonding and pressing the carrier substrate carrying the LED light-emitting wafer with the circuit board.

The highest precision of the PCB is only 1.5mil (38 μm) at present, and the pad pitch of LED luminous chips with Mini LEDs below P1.0 (i.e. pixel pitch of 1.0 mm), especially below P0.5, is only 50 μm, so that the precision is very difficult to improve in consideration of the material and the manufacturing process of the PCB. Therefore, in some embodiments of the present invention, a glass substrate is used as a wiring board to improve the accuracy of the wiring, thereby improving the resolution.

Specifically, in the above embodiment, the first insulating layer 112, the second insulating layer 114, and the third insulating layer 116 in the circuit board 110 are glass. Since the glass has good flatness, the first and second pad layers 111 and 117 may be formed on the first and third insulating layers 112 and 116, respectively, by evaporation, the first line layer 113 may be formed on a side of the first insulating layer 112 away from the first pad layer 111, or on a side of the second insulating layer 114 close to the first insulating layer 112, by inkjet printing, screen printing, or the like, and the second line layer 115 may be formed on a side of the second insulating layer 114 close to the third insulating layer 116, or on a side of the third insulating layer 116 close to the second insulating layer 114, by inkjet printing, screen printing, or the like. In one embodiment of the present invention, adjacent insulating layers are bonded by lamination, and in a corresponding manner, two or more conductive vias 118 in the first pad layer 111, the second pad layer 117, the first circuit layer 113, and the second circuit layer 115 penetrate through the glue between the insulating layers.

In the above embodiment, the first circuit layer and the second circuit layer are respectively located at two sides of the second insulating layer, and the first circuit layer and the second circuit layer are communicated through conductive vias penetrating through the insulating layer. In other embodiments of the present invention, the first circuit layer is located at a side of the first insulating layer away from the first pad layer, the second circuit layer is located at a side of the second insulating layer close to the first insulating layer, a glue layer is disposed between the first circuit layer and the second circuit layer, and a conductive via hole for connecting the first circuit layer and the second circuit layer is formed on the glue layer, and the glue layer is simultaneously used for bonding the first insulating layer and the second insulating layer. According to the scheme, the number of holes punched in glass can be reduced, the production cost is reduced, and the through holes in the colloid layer between the first circuit layer and the second circuit layer can be formed in an exposure etching mode, so that the size precision of the through holes is improved.

The lines in the first line layer 113 and the second line layer 115 are nano silver lines, carbon nanotubes, ITO nanowires, zinc oxide nanowires, or the like. Specifically, a precursor liquid for forming the circuit can be printed on glass in an inkjet printing mode to form a required pattern, and then the glass comprising the pattern is subjected to heat treatment to sinter the liquid circuit into a solid circuit.

Since the insulating layer in the circuit board 110 is glass, the minimum aperture that can be obtained by the existing mechanical drilling method is 0.2mm, the required precision is not achieved, and the mechanical drilling easily causes glass cracking. Thus, in the embodiment of the present invention, the conductive via 118 is formed by laser drilling, and the aperture of the conductive via 118 is in the range of 10 μm to 15 μm.

Example two

Fig. 2 is a schematic structural diagram of a display module capable of being spliced according to a second embodiment of the present invention, and fig. 3 is an enlarged view of a region a in fig. 2, as shown in fig. 2 and 3, in this embodiment, the display module capable of being spliced includes a circuit board 210, a driving module 220, a plurality of LED light emitting chips 230, and a light-transmitting carrier substrate 240.

The circuit board 210 includes a first pad layer 211, a first insulating layer 212, a first circuit layer 213, a second insulating layer 214, a second circuit layer 215, a third insulating layer 216, and a second pad layer 217, which are stacked in this order.

The LED light emitting die 230 is disposed on the first pad layer 211 and electrically connected to the first pad layer 211, and the driving module 220 is disposed on the second pad layer 217 and electrically connected to the second pad layer 217. The first pad layer 211, the second pad layer 217, the first line layer 213 and the second line layer 215 are electrically connected through the conductive via 218 penetrating the insulating layer, thereby realizing the electrical connection of the driving module 220 and the LED light emitting chip 230, so that the LED light emitting chip 230 can emit light in response to the driving signal emitted from the driving module 220. The conductive via 218 is a hole penetrating through the insulating layer, and the inner wall of the hole is provided with a conductive material, so that two layers connected by the conductive via 218 are conducted. In other embodiments of the present invention, the first circuit layer is located at a side of the first insulating layer away from the first pad layer, the second circuit layer is located at a side of the second insulating layer close to the first insulating layer, a glue layer is disposed between the first circuit layer and the second circuit layer, and a conductive via hole for connecting the first circuit layer and the second circuit layer is formed on the glue layer, and the glue layer is simultaneously used for bonding the first insulating layer and the second insulating layer. According to the scheme, the number of holes punched in glass can be reduced, the production cost is reduced, and the through holes in the colloid layer between the first circuit layer and the second circuit layer can be formed in an exposure etching mode, so that the size precision of the through holes is improved.

The first insulating layer 212, the second insulating layer 214, and the third insulating layer 216 in the wiring board 210 are glass. The wires in the wire layer in the wire board 210 are nano silver wires, carbon nanotubes, ITO nanowires or zinc oxide nanowires. The conductive vias 218 have a pore size in the range of 10 μm to 15 μm.

The carrier substrate 240 may be transparent glass or polyimide, a transparent die bonding structure 241 for fixing the LED light emitting wafer 230 is disposed on the carrier substrate 240, and the LED light emitting wafer 230 is fixed on the die bonding structure 241. Specifically, the die bonding structure 241 may be a limiting groove with a limiting effect or an adsorption pad with an adsorption effect, which is used for capturing the LED light emitting wafer 230 in the process of transferring the LED light emitting wafer 230 onto the carrier substrate 240, so that the LED light emitting wafer 230 is fixed on the die bonding structure 241.

The LED lighting die 230 may be Mini-LEDs or Micro-LEDs, and since the LED lighting die 230 is small in size, if the LED lighting die 230 is fixed to the circuit board 210 one by one, the fixing efficiency will be very low. Therefore, in the embodiment of the present invention, the LED light emitting chip 230 is first transferred onto the carrier substrate 240 by mass transfer, so that the LED light emitting chip 230 is fixed on the die bonding structure 241. Then, the carrier substrate 240 carrying the LED lighting chip 230 is attached to the circuit board 210, so that the LED lighting chip 230 is electrically connected to the first pad layer 211 on the circuit board 210, thereby improving the fixing efficiency of the LED lighting chip 230.

In one embodiment of the present invention, as shown in fig. 3, the die attach structure 241 includes a positioning groove formed by the protrusions 2411 disposed on the carrier substrate 240, and the LED lighting chip 230 is fixed in the positioning groove. The number of the protrusions 2411 forming the positioning groove may be four for surrounding the circumference of the LED light emitting wafer 230, or the number of the protrusions 2411 forming the positioning groove may be two for surrounding the opposite sides of the LED light emitting wafer 230, and in the embodiment of the present invention, the present invention will be described by taking two protrusions 2411 forming the positioning groove as an example. The positioning groove can improve the position accuracy of the LED lighting chip 230 on the carrier substrate 240, so that the carrier substrate 240 has higher position accuracy when being pressed with the circuit board 210.

In the above-described embodiments, the type of the LED light emitting wafer is not limited, and may be a front-mounted wafer, a flip-chip, or a vertical wafer. In one embodiment of the present invention, the LED light emitting die 230 is a vertical die that has a smaller size relative to the front-side die and the flip-chip die, and the same area can be provided with more light emitting dies, i.e., the pixel density (Pixels Per Inch, PPI) of the display module is increased. Fig. 4 is a schematic structural diagram of a vertical wafer according to an embodiment of the present invention, where the vertical wafer includes a first electrode 231, a conductive layer 232, a distributed bragg reflection layer 233, a P-type layer 234, a light emitting layer 235, and an N-type layer 236 stacked in sequence.

Specifically, the first electrode 231 may be silver, the conductive layer 232 may be Indium Tin Oxide (ITO), the distributed bragg reflection layer 233 is a periodic structure formed by alternately arranging two materials with different refractive indexes, the optical thickness of each layer of material is 1/4 of the central reflection wavelength, and the reflectivity of the distributed bragg reflection layer 233 can reach more than 99%, so that light emitted by the light emitting layer 235 is emitted by the N-type layer 236 after being reflected, and the light is used for improving the brightness of the LED. The P-type layer 234 may be P-type gallium nitride, the light emitting layer 235 may be a Multi Quantum-Well (MQW), and the N-type layer 236 may be N-type gallium nitride.

As shown in fig. 3, the die attach structure 241 further includes a die attach pad 2412 formed on the carrier substrate 240, and the protrusions 2411 are disposed on at least one edge of opposite sides of the die attach pad 2412, and in an exemplary embodiment of the invention, the protrusions 2411 are disposed on one edge of opposite sides of the die attach pad 2412. Illustratively, the first wiring layer 213, the second wiring layer 215, and the conductive via 218 are electrically connected by a suitable arrangement such that the same column or row of die bonding pads 2412 are electrically connected such that the same column or row of LED light emitting chips are simultaneously driven to emit light.

As shown in fig. 3, the first pad layer 211 includes a plurality of first pads 2111 and a plurality of second pads 2112, the first electrode 231 of the vertical wafer is electrically connected to the first pad 2111 corresponding to the vertical wafer, the die bonding pad 2412 is used as the second electrode of the vertical wafer, and the die bonding pad 2412 is electrically connected to the second pad 2112 corresponding to the vertical wafer.

Illustratively, the bump 2411 is a conductive bump, an anisotropic conductive paste 250 is disposed between the circuit board 210 and the carrier substrate 240, the anisotropic conductive paste 250 has a property of conducting in a vertical direction, the first electrode 231 of the vertical wafer is electrically connected to the first pad 2111 through the anisotropic conductive paste 250, the bump 2411 is electrically connected to the second pad 2112 through the anisotropic conductive paste 250, and the die bonding pad 2412 is electrically connected to the second pad 2112.

Illustratively, as shown in fig. 3 and 4, in one embodiment of the present invention, the sidewalls of the vertical wafer are provided with an insulating protective layer 237. The insulating protective layer 237 serves to isolate layers in the vertical wafer from the protrusions 2411, avoiding shorting of the protrusions 2411 to layers in the vertical wafer.

In the embodiment of the present invention, since the insulating layer in the circuit board 210 is made of transparent glass, in order to avoid the electronic components on the circuit board 210 from affecting the display, in some embodiments of the present invention, the first insulating layer 212 in the circuit board 210 is near the surface of the carrier substrate 240, the area outside the bonding pad is coated with an ink layer (not shown in the figure) or other dark treatment, or the surface of the carrier substrate 240 near the circuit board 210, the area outside the die bonding structure 241 is coated with an ink layer (not shown in the figure) or other dark treatment, or a black transparent glass substrate is used as the carrier substrate 240, so as to shield the electronic components on the circuit board 210 from affecting the normal display, and improve the contrast ratio of the display device.

According to the display module capable of being spliced, the LED light emitting wafers and the driving modules are respectively arranged on two opposite sides of the circuit board, so that one side of the circuit board, on which the LED light emitting wafers are arranged, is not required to be provided with a region for fixing the driving modules, namely, the edge of the side is not provided with a region without the LED light emitting wafers, and further, in a display screen formed by splicing, a region without the LED light emitting wafers does not exist at a splicing joint between two mutually spliced LED display modules, and therefore, the pixel interval at the splicing joint is reduced, the resolution of the display screen is improved, and the display effect is optimized. The glass substrate is used as a circuit board to improve the circuit precision and further improve the resolution. The LED luminous wafer is transferred to the proper position on the carrier substrate in advance, and then the carrier substrate carrying the LED luminous wafer is attached to the circuit board, so that the efficiency and the position accuracy of fixing the LED luminous wafer on the circuit board are improved.

Example III

Fig. 5 is a schematic flow chart of a method for manufacturing a display module capable of being spliced according to the third embodiment of the present invention, as shown in fig. 5, and the method specifically includes the following steps:

S11, providing a circuit board.

Specifically, the circuit board includes first pad layer and second pad layer that relative set up to and be located at least one deck circuit layer between first pad layer and the second pad layer, be provided with the insulating layer between adjacent two-layer in first pad layer, second pad layer and the at least one deck circuit layer, first pad layer, second pad layer and at least one deck circuit layer are connected through the conductive via electricity that runs through the insulating layer. Specifically, the structure of the circuit board may refer to the content of the first embodiment of the present invention and fig. 1, and the embodiment of the present invention is not described herein again.

S12, providing a light-transmitting carrier substrate.

In particular, the carrier substrate may be a light-transmitting glass or polyimide.

S13, forming a light-transmitting die bonding structure for fixing the LED luminous wafer on the carrier substrate.

Specifically, a light-transmitting die bonding structure for fixing the LED light emitting wafer can be formed on the carrier substrate in a printing manner, and the die bonding structure can be a limiting groove with a limiting function or an adsorption pad with an adsorption function and is used for capturing the LED light emitting wafer in the process of transferring the LED light emitting wafer to the carrier substrate, so that the LED light emitting wafer is fixed on the die bonding structure. For example, the die attach structure on the carrier substrate may refer to the content of the first embodiment of the present invention and the embodiment of fig. 1, which are not described herein.

S14, fixing the LED luminous wafer on the die bonding structure on the carrier substrate.

Specifically, the LED light emitting wafer may be transferred to the carrier substrate by a mass transfer method or the like, so that the LED light emitting wafer is fixed on the die bonding structure, and the specific transfer method is not limited herein in the embodiment of the present invention.

And S15, pressing the carrier substrate and the circuit board to electrically connect the LED luminous wafer with the first bonding pad layer.

Specifically, a carrier substrate carrying an LED light emitting wafer is attached to a circuit board, so that the LED light emitting wafer is electrically connected with a first bonding pad layer on the circuit board. The bonding method may be hot pressing, bonding, etc., and the embodiment of the present invention is not limited herein.

S16, fixing the driving module on the second bonding pad layer, and electrically connecting the driving module with the second bonding pad layer.

Specifically, the driving module may be fixed on the second pad layer by welding, gluing, or the like, which is not limited herein. After the driving module is fixed, the driving module is electrically connected with the second bonding pad layer.

After the above steps, the specific structure of the obtained display module may refer to the content described in the first embodiment of the present invention and fig. 1, and the embodiment of the present invention is not described herein again.

It should be noted that, in the embodiment of the present invention, the specific order of the steps is not limited, and in other embodiments of the present invention, step S16 may be performed first, and after the driving module is fixed on the second pad layer, steps S12 to S15 may be performed.

In the present embodiment, the type of the LED light emitting chip is not limited, and may be a front-mounted chip, a flip chip, or a vertical chip.

According to the preparation method of the display module capable of being spliced, the LED light-emitting wafers and the driving modules are respectively arranged on two opposite sides of the circuit board, so that one side of the circuit board, on which the LED light-emitting wafers are arranged, is not required to be provided with a region for fixing the driving modules, namely, the edge of the side is not provided with a region without the LED light-emitting wafers, and further, in a display screen formed by splicing, a region without the LED light-emitting wafers is not provided at a splicing joint between two mutually spliced LED display modules, and therefore, the pixel interval at the splicing joint is reduced, the resolution of the display screen is improved, and the display effect is optimized. Through being provided with the solid brilliant structure that is used for fixing the printing opacity of LED luminescent wafer at the carrier substrate, transfer the LED luminescent wafer to the solid brilliant structure on the carrier substrate in advance, then laminate carrier substrate and the circuit board that bear the weight of the LED luminescent wafer, improve the efficiency and the positional accuracy that the LED luminescent wafer was fixed to the circuit board.

Example IV

Fig. 6 is a schematic flow chart of a method for manufacturing a display module capable of being spliced according to a fourth embodiment of the present invention, as shown in fig. 6, the method specifically includes the following steps:

S21, providing a circuit board.

Fig. 7 is a schematic structural diagram of a circuit board according to an embodiment of the present invention, and as shown in fig. 7, a circuit board 310 includes a first pad layer 311, a first insulating layer 312, a first circuit layer 313, a second insulating layer 314, a second circuit layer 315, a third insulating layer 316, and a second pad layer 317 stacked in sequence. The first pad layer 311, the second pad layer 317, the first line layer 313, and the second line layer 315 are electrically connected through conductive vias 318 penetrating the insulating layer. The conductive via 318 is a hole penetrating through the insulating layer, and the inner wall of the hole is provided with a conductive material, so that two or more layers connected by the conductive via 318 realize conduction.

The first insulating layer 312, the second insulating layer 314, and the third insulating layer 316 in the wiring board 310 are glass. The first pad layer 311 and the second pad layer 317 may be formed on the first insulating layer 312 and the third insulating layer 316, respectively, by evaporation, and the first line layer 313 may be formed on a side of the first insulating layer 312, which is far from the first pad layer 311, or a side of the second insulating layer 314, which is close to the first insulating layer 312, by inkjet printing, screen printing, or the like, and the second line layer 315 may be formed on a side of the second insulating layer 314, which is close to the third insulating layer 316, or a side of the third insulating layer 316, which is close to the second insulating layer 314, by inkjet printing, screen printing, or the like. And the adjacent insulating layers are bonded in a pressing mode.

The lines in the first line layer 313 and the second line layer 315 are nano silver lines, carbon nanotubes, ITO nanowires, zinc oxide nanowires, or the like. Specifically, a precursor liquid for forming the circuit can be printed on glass in an inkjet printing mode to form a required pattern, and then the glass comprising the pattern is subjected to heat treatment to sinter the liquid circuit into a solid circuit.

The conductive via 318 is formed by laser drilling, and the aperture of the conductive via 318 ranges from 10 μm to 15 μm.

The first pad layer 311 includes a plurality of first pads 3111 and a plurality of second pads 3112.

S22, providing a light-transmitting carrier substrate.

S23, forming a plurality of light-transmitting die bonding pads on the carrier substrate.

Fig. 8 is a schematic diagram of forming a die bond pad on a carrier substrate according to an embodiment of the present invention, as shown in fig. 8, a plurality of light-transmitting die bond pads 3412 distributed in an array may be formed on a carrier substrate 340 by vapor deposition, and the die bond pads 3412 may be light-transmitting ITO layers.

S24, forming conductive bulges on at least one edge of two opposite sides of the die bonding pad, wherein the conductive bulges form positioning grooves.

Fig. 9 is a schematic diagram of forming conductive bumps on a die bonding pad according to an embodiment of the present invention, and fig. 10 is a top view of the conductive bumps in fig. 9, where, as shown in fig. 9 and fig. 10, conductive bumps 3411 are formed on edges of opposite sides of the die bonding pad 3412 by inkjet printing, so as to form positioning grooves. The positioning groove can improve the position accuracy of the LED lighting chip 330 on the carrier substrate 340, so that the subsequent carrier substrate 340 has higher position accuracy when being pressed with the circuit board 310.

Further, after step S25, it may further include coating an ink layer (not shown) or other dark color treatment on the surface of the first insulating layer 312 in the circuit board 310, or coating an ink layer (not shown) or other dark color treatment on the surface of the carrier substrate 340 provided with the die bonding pad 3412, or coating an ink layer (not shown) or other dark color treatment on the area of the carrier substrate 340, or using a black transparent glass substrate as the carrier substrate 340, for shielding the electronic components on the circuit board 310 from affecting normal display, and improving the contrast of the display device.

S25, transferring the vertical wafer into the positioning groove.

Fig. 11 is a schematic diagram of transferring vertical wafers into positioning slots according to an embodiment of the present invention, as shown in fig. 11, a plurality of vertical wafers 330 are transferred onto a carrier substrate 340 at a time by a mass transfer device M, wherein each vertical wafer 330 is fixed in a corresponding positioning slot. The vertical wafer 330 includes a first electrode, a conductive layer, a distributed bragg reflection layer, a P-type layer, a light emitting layer, and an N-type layer, which are stacked in this order. The specific structure of the vertical wafer may refer to the second embodiment of the present invention and fig. 4, and the embodiment of the present invention is not described herein again. When the vertical wafer 330 is secured in the positioning slots, the N-type layer of the vertical wafer 330 is in contact with and electrically connected to the die bond pads 3412 on the carrier substrate 340.

The mass transfer device M of the present embodiment has a suction plate having a plurality of suction positions thereon, each suction position being capable of sucking a vertical wafer 330. In the transfer process, the plurality of vertical wafers 330 are first adsorbed on the adsorption plate, and then the adsorption plate is moved to a predetermined station above the carrier substrate 340, and the vertical wafers 330 are released so that the vertical wafers 330 fall into the positioning grooves formed by the conductive bumps 3411.

It should be noted that, the mass transfer device in the embodiment of the present invention may use electrostatic adsorption, magnetic adsorption or negative pressure adsorption to adsorb the vertical wafer, which is not limited herein.

S26, coating anisotropic conductive adhesive on one side of the carrier substrate, on which the die bonding pad is arranged.

Specifically, the anisotropic conductive adhesive is coated on the side of the carrier substrate on which the die bonding pad is disposed, or the anisotropic conductive adhesive is coated on the side of the circuit board on which the first pad layer is disposed, or the anisotropic conductive adhesive is simultaneously coated on the side of the carrier substrate on which the die bonding pad is disposed and the side of the circuit board on which the first pad layer is disposed, which is not limited herein. Fig. 12 is a schematic diagram of an embodiment of applying an anisotropic conductive paste on a side of a carrier substrate provided with a die bond pad, and as shown in fig. 12, an exemplary embodiment of applying an anisotropic conductive paste 350 on a side of a carrier substrate 340 provided with a die bond pad 3412, wherein the anisotropic conductive paste 350 covers an upper surface of a vertical wafer 330.

And S27, pressing the carrier substrate and the circuit board.

Specifically, the carrier substrate and the circuit board are pressed together in a hot pressing mode, wherein the hot pressing process has the parameters that the heating condition is 100-120 ℃, the pressing time is 1s-2s, and the pressing pressure is 8kg/mm ²-12kg/mm². Fig. 13 is a schematic diagram of bonding a carrier substrate to a circuit board according to an embodiment of the present invention, as shown in fig. 13, an anisotropic conductive paste 350 has a characteristic of conducting in a vertical direction, a first electrode of a vertical die 330 after bonding is electrically connected to a first bonding pad 3111 corresponding to the vertical die 330 through the anisotropic conductive paste 350, and a conductive bump 3411 is electrically connected to a second bonding pad 3112 corresponding to the vertical die 330 through the anisotropic conductive paste 350, so that a die bonding pad 3412 is electrically connected to the second bonding pad 3112. Specifically, the specific connection structure between the vertical wafer and the first pad and the specific connection structure between the vertical wafer and the second pad may refer to the second embodiment of the present invention and fig. 3, and the embodiments of the present invention are not described herein again.

And S28, fixing the driving module on the second bonding pad layer, and electrically connecting the driving module with the second bonding pad layer.

Specifically, the driving module can be fixed on the second bonding pad layer in a welding mode, a cementing mode and the like, and after the driving module is fixed, the driving module is electrically connected with the second bonding pad layer. Fig. 14 is a schematic diagram of fixing a driving module on a second pad layer according to an embodiment of the present invention, as shown in fig. 14, the second pad layer 317 may include a plurality of pads, and the driving module 320 is fixed on one or more of the pads and electrically connected to one or more of the pads, so that the driving module 320 can send a driving signal to the vertical die 330 through the circuit board 310, thereby lighting the vertical die 330. The other pads of the second pad layer 317 may serve as interfaces with external circuits for connecting external power and data signals.

According to the preparation method of the display module capable of being spliced, the LED light-emitting wafers and the driving modules are respectively arranged on two opposite sides of the circuit board, so that one side of the circuit board, on which the LED light-emitting wafers are arranged, is not required to be provided with a region for fixing the driving modules, namely, the edge of the side is not provided with a region without the LED light-emitting wafers, and further, in a display screen formed by splicing, a region without the LED light-emitting wafers is not provided at a splicing joint between two mutually spliced LED display modules, and therefore, the pixel interval at the splicing joint is reduced, the resolution of the display screen is improved, and the display effect is optimized. The glass substrate is used as a circuit board to improve the circuit precision and further improve the resolution. Through forming solid brilliant pad on carrier substrate, form conductive protruding on solid brilliant pad, conductive protruding forms the constant head tank, can improve the position accuracy of LED luminescent wafer on carrier substrate for carrier substrate has higher position accuracy when pressing with the circuit board.

The embodiment of the invention also provides a display device which comprises the spliced display module provided by the embodiment, and particularly the display device is formed by splicing a plurality of spliced display modules. Because LED luminescence wafer and drive module set up in the opposite both sides of circuit board respectively, like this, be provided with the one side of LED luminescence wafer on the circuit board, need not to set up the region that is used for fixing drive module, the edge of this side does not have the region that does not have LED luminescence wafer, and then in the display screen that the concatenation formed, the splice seam department between two LED display modules of mutual concatenation does not have the region that does not have LED luminescence wafer, and then reduced the pixel interval of splice seam department, improved the resolution ratio of display screen, optimized the display effect. In addition, the efficiency and the position accuracy of fixing the LED light emitting wafer on the circuit board are improved by transferring the LED light emitting wafer onto the die bonding structure on the carrier substrate in advance and then attaching the carrier substrate carrying the LED light emitting wafer to the circuit board.

In the description herein, it should be understood that the terms "upper," "lower," "left," "right," and the like are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and to simplify operation, rather than to indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

In the description herein, reference to the term "one embodiment," "an example," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples.

Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in the foregoing embodiments, and that the embodiments described in the foregoing embodiments may be combined appropriately to form other embodiments that will be understood by those skilled in the art.

The technical principle of the present invention is described above in connection with the specific embodiments. The description is made for the purpose of illustrating the general principles of the invention and should not be taken in any way as limiting the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of this specification without undue burden.

Claims

1. The display module capable of being spliced is characterized by comprising a light-transmitting carrier substrate, a circuit board, a driving module and a plurality of LED luminous wafers;

the carrier substrate is provided with a light-transmitting die bonding structure for fixing the LED luminous wafer, and the LED luminous wafer is fixed on the die bonding structure;

The LED luminous wafer is a vertical wafer, the first bonding pad layer comprises a plurality of first bonding pads and a plurality of second bonding pads, the bulges are conductive bulges, anisotropic conductive adhesive is arranged between the circuit board and the carrier substrate, a first electrode of the vertical wafer is electrically connected with the first bonding pads through the anisotropic conductive adhesive, and the bulges are electrically connected with the second bonding pads through the anisotropic conductive adhesive.

2. The tileable display module of claim 1, wherein the LED lighting die is secured within the detent.

3. The tileable display module of claim 2, wherein the die attach structure further comprises die attach pads formed on the carrier substrate, the bumps being disposed on edges of at least one opposing side of the die attach pads;

The first electrode of the vertical wafer is electrically connected with the first bonding pad corresponding to the vertical wafer, the die bonding pad is used as the second electrode of the vertical wafer, and the die bonding pad is electrically connected with the second bonding pad corresponding to the vertical wafer.

4. The tiled display module of claim 1, wherein the vertical wafer comprises a first electrode, a conductive layer, a distributed bragg reflective layer, a P-type layer, a light emitting layer, and an N-type layer, stacked in that order.

5. The tiled display module according to claim 1, wherein the sidewalls of the vertical wafers are provided with an insulating protective layer.

6. The tileable display module according to any one of claims 1-5, wherein the wiring board comprises, in order, a first pad layer, a first insulating layer, a first wiring layer, a second insulating layer, a second wiring layer, a third insulating layer, and a second pad layer;

7. The tileable display module of claim 6, wherein the insulating layer is glass and the wires in the wire layer are nano-silver wires, carbon nanotubes, ITO nanowires, or zinc oxide nanowires.

8. The tileable display module of claim 1, wherein the conductive via has a pore size ranging from 10 μιη to 15 μιη.

9. The preparation method of the display module capable of being spliced is characterized by comprising the following steps of:

Providing a light-transmitting carrier substrate;

Fixing a driving module on the second bonding pad layer, wherein the driving module is electrically connected with the second bonding pad layer;

The LED light-emitting wafer is a vertical wafer, and a light-transmitting die bonding structure for fixing the LED light-emitting wafer is formed on the carrier substrate, and the LED light-emitting wafer comprises:

forming conductive protrusions on at least one edge of two opposite sides of the die bonding pad, wherein the conductive protrusions form positioning grooves;

the first bonding pad layer comprises a plurality of first bonding pads and a plurality of second bonding pads, and is used for pressing the carrier substrate and the circuit board, and the method comprises the following steps:

10. The method of claim 9, wherein forming conductive bumps on at least one of two opposite sides of the die pad comprises:

11. A display device comprising a tiled display module according to any of claims 1-8.