Micro LED light source module and its preparation method, LED printing equipment

Abstract

This invention provides a micro-LED light source module, its fabrication method, and a printing device. The fabrication method includes: providing a substrate to fabricate multiple micro-LED chips; providing a fan-out substrate with multiple chip receiving areas, each chip receiving area for receiving a number of micro-LED chips; transferring multiple micro-LED chips to the multiple chip receiving areas to rearrange the multiple micro-LED chips on the fan-out substrate into multiple light-emitting array units, and cutting the multiple light-emitting array units to form corresponding multiple splicing modules, wherein each splicing module has fan-out pads, and the number of fan-out pads is less than the number of chip electrodes in each light-emitting array unit; and providing a carrier substrate, the carrier substrate including splicing areas and multiple pad electrodes, fixing the multiple splicing modules in the splicing areas, and electrically connecting the multiple fan-out pads and the multiple pad electrodes to obtain the micro-LED light source module.

Description

Technical Field

[0001] This invention relates to the field of printing technology, and in particular to a micro-LED light source module used in LED (light-emitting diode) printing equipment and its preparation method. Background Technology

[0002] Existing printers can be divided into two-dimensional (2D) printers and three-dimensional (3D) printers. 2D printers, based on their printing principles, can be further categorized into inkjet printers, laser printers, and LED printers. LED printers, in particular, utilize a set of light-emitting diodes (LEDs) to achieve scanning and photosensitive imaging. Specifically, a dense array of micro-LEDs serves as the light emitter, converting the electrical signals of the data information into light signals, which are then emitted onto a photosensitive drum to form an image.

[0003] 3D printing, also known as additive manufacturing, can be categorized based on the type of product or material used. The International Organization for Standardization (ISO) classifies it into seven types: material extrusion, reduction polymerization, powder bed fusion, material jetting, binder jetting, directional energy deposition, and sheet lamination. Reduction polymerization typically uses a point light source to selectively cure (or harden) a photosensitive polymer resin. The light source is usually a laser paired with a galvanometer (DLP) or a UV light source paired with a liquid crystal display (LCD), or it can be provided by a dense micro-LED chip array. Dense micro-LED chip arrays offer advantages such as high resolution and more precise light source drive control.

[0004] Therefore, how to fabricate dense microLED chip arrays for use as light source modules in 2D and 3D printers has become an urgent technical problem to be solved. Currently, OKI printers in Japan propose first bonding a compound semiconductor thin film onto a driver chip (silicon-based IC), then etching a microLED chip array using semiconductor processes. Finally, the microLED chips are electrically connected to the silicon-based IC via wire bonding to form a microLED display module. Many microLED display modules are then spliced ​​onto a circuit board (PCB), and finally, wire bonding is used to electrically connect the silicon-based IC of each module to the PCB. However, the above process has the following drawbacks: The process of transferring a semiconductor thin film onto a driver chip (silicon-based IC) before fabricating the microLED array results in wasted areas of the semiconductor thin film corresponding to the silicon-based IC, leading to low utilization of the semiconductor thin film and directly causing high manufacturing costs for microLED display modules. Furthermore, because the microLED structure is fabricated on a silicon-based IC, the silicon-based IC can only be placed on one side of the microLED array. Therefore, the silicon-based IC needs to be densely arranged, which negatively impacts the luminous efficiency of the microLEDs, such as reducing luminous efficiency.

[0005] Therefore, this application proposes a new method for fabricating micro-LED array light sources to overcome the defects in existing micro-LED light source array fabrication processes for printers. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a micro-LED light source module and its fabrication method, as well as an LED printing device. By adopting a fabrication scheme of "mass-transferring micro-LED chips on a wafer, fanning them out for interconnection, and then modularly splicing them," the invention solves the problems of high fabrication cost, poor electrical connection reliability, and inadequate heat dissipation of micro-LED array light sources in existing printing devices.

[0007] This application provides a fan-out fabrication method for a micro-LED light source module, comprising: A substrate is provided, on which a plurality of microLED chips are fabricated; A fan-out substrate is provided, wherein the fan-out substrate is provided with a plurality of chip receiving areas, and each chip receiving area is used to receive a plurality of microLED chips; Multiple microLED chips are transferred to multiple chip receiving areas to rearrange the microLED chips into multiple light-emitting array units on the fan-out substrate, and the multiple light-emitting array units are cut to form corresponding multiple splicing modules, wherein each splicing module has a fan-out pad, and the number of fan-out pads is less than the total number of chip electrodes in each light-emitting array unit; and A carrier substrate is provided, the carrier substrate including a splicing area and multiple pad electrodes, the multiple splicing modules are fixed in the splicing area, and the multiple fan-out pads and multiple pad electrodes are electrically connected to obtain the micro LED light source module.

[0008] As an optional technical solution, the fan-out substrate has a pre-set fan-out line and a plurality of fan-out pads, the fan-out line and the fan-out pads being located outside the receiving area of ​​each chip.

[0009] As an optional technical solution, the fan-out substrate does not have pre-set fan-out lines and multiple fan-out pads, and further includes: A molding compound is formed on the fan-out substrate, the molding compound covering the plurality of microLED chips, and the chip electrode of each microLED chip is exposed from the molding compound; The fan-out lines and the plurality of fan-out pads are electrically connected on the molding compound; and Multiple connection electrodes are formed on the molding layer. The multiple connection electrodes are electrically connected to the corresponding fan-out line and the chip electrode of the corresponding micro LED chip. The number of connection electrodes is less than the total number of chip electrodes in each corresponding light-emitting array unit.

[0010] As an optional technical solution, the multiple fan-out pads and the chip electrodes of the multiple microLED chips are located on the same side of the fan-out substrate, or the multiple fan-out pads and the corresponding chip electrodes of the multiple microLED chips are located on opposite sides of the fan-out substrate.

[0011] As an optional technical solution, when the chip electrodes of the multiple fan-out pads and the multiple microLED chips are located on the same side of the fan-out substrate, wire bonding is used to connect the multiple chip electrodes and the multiple fan-out pads. When the multiple fan-out pad electrodes and the corresponding multiple microLED chip electrodes are located on opposite sides of the fan-out substrate, the multiple chip electrodes and the multiple fan-out pads are flip-chip bonded.

[0012] As an optional technical solution, it also includes forming a reflective layer in one of the multiple chip receiving areas.

[0013] As an optional technical solution, multiple microLED chips are transferred to multiple chip receiving areas, and a light-blocking barrier is formed between any adjacent microLED chips.

[0014] As an optional technical solution, multiple microLED chips are transferred to multiple chip receiving areas, and a microlens structure is fabricated on each microLED chip. The microlens structure is used to converge the emission angle of the microLED chip.

[0015] As an optional technical solution, multiple microLED chips are transferred to multiple chip receiving areas, a transparent adhesive layer is prepared on the fan-out substrate, the transparent adhesive layer is patterned, the transparent adhesive layer covers the microLED chips, and the light transmittance of the transparent adhesive layer is >90%.

[0016] As an optional technical solution, multiple microLED chips are transferred to multiple chip receiving areas, wherein in each chip receiving area, multiple microLED chips are linearly arranged at equal intervals along a row or column direction; or... In each of the chip receiving areas, multiple micro-LED chips form multiple first minimum repeating units, and the multiple first minimum repeating units are arranged at equal intervals along the row direction or column direction.

[0017] As an optional technical solution, the splicing area is a long strip-shaped area preset on the carrier substrate. The number of the long strip-shaped areas is multiple, and the multiple long strip-shaped areas are arranged at equal intervals along the row direction on the carrier substrate, and arranged in a stepped manner along the column direction on the carrier substrate.

[0018] As an optional technical solution, multiple splicing modules are arranged linearly at equal intervals along the row or column direction on the carrier substrate; or... Multiple splicing modules form multiple second minimum repeating units on the carrier substrate, and the multiple second minimum repeating units are arranged at equal intervals and staggered along the row direction or column direction.

[0019] As an optional technical solution, it also includes: forming a fixing adhesive layer between the plurality of splicing modules and the carrier substrate.

[0020] The present invention also provides a micro-LED light source module, which is prepared by the preparation method described in any of the above claims.

[0021] As an optional technical solution, multiple microLED chips are recombined into multiple light-emitting array units. Each light-emitting array unit is divided into C light-emitting sub-units, and each light-emitting sub-unit contains N microLED chips. The N microLED chips are electrically connected in a common cathode or common anode structure. The splicing module includes fan-out pads, which are provided with first fan-out pads and second fan-out pads. The number of second fan-out pads is C, and each second fan-out pad is configured to provide a common electrical signal to a corresponding light-emitting sub-unit. The number of first fan-out pads is at least equal to the N microLED chips in a light-emitting sub-unit, and each first fan-out pad is configured to independently provide a driving electrical signal to the microLED chips located in the same sequence position in the C light-emitting sub-units, so that each microLED chip can be independently lit.

[0022] As an optional technical solution, the C light-emitting sub-units are reorganized into M light-emitting parent units, each of the light-emitting parent units contains at least one light-emitting sub-unit, and M≤C; wherein, each light-emitting parent unit is configured with a set of first fan-out pads, and each set of first fan-out pads is configured to provide driving electrical signals to all light-emitting sub-units within a corresponding light-emitting parent unit, so that each microLED chip can be lit independently; the total number of first fan-out pads in each splicing module is M*N.

[0023] The present invention also provides an LED printing device, the printing device comprising the micro LED light source module as described above.

[0024] In summary, this invention provides a micro-LED light source module and its fabrication method, as well as an LED printing device. The micro-LED light source module fabrication method includes: In the process of first transferring the micro-LED chips fabricated on the compound wafer to the fan-out substrate to form several light-emitting array units, these micron-sized chips can be transferred and temporarily fixed on the fan-out substrate with high precision in one go. Multiple periodically arranged micro-LED chip light-emitting array units with consistent spacing are formed on the fan-out substrate according to a preset spacing. The pre-formation of micro-LED chips results in high utilization of the compound film. Combined with the mass transfer technology, there is a significant cost advantage. Next, the electrodes of the microLED chips in each light-emitting array unit are fanned out to form fan-out pads, thus enlarging the size of the fan-out pads. The fan-out process achieves "enlargement" of the physical size of the electrodes on the microLED chips and a significant reduction in the number of electrodes (common anode / common cathode fan-out pads, multiple light-emitting sub-units in each parent light-emitting unit of the reorganized light-emitting array unit provide drive signal input by sharing a set of fan-out pads). The large-size fan-out pads provide a foundation for reliable interconnection with the pad electrodes of the circuit board in the future. Finally, the multiple light-emitting array units on the fan-out substrate are cut into multiple splicing modules, which are then spliced ​​onto a circuit board (PCB / TGV) with a driver chip. The fan-out pads and the circuit board pad electrodes are electrically connected. Due to their larger physical size, the splicing modules are easier to install and connect. Furthermore, the driver chip is centrally located on the back of the system circuit board or in a non-light-emitting area, physically separated from the light-emitting micro-LED array. This effectively eliminates the direct "thermal interference" of the driver chip's heat on the micro-LED's luminous efficiency (temperature rise leads to efficiency reduction), improving the overall system's thermal stability and electrical performance. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 A flowchart of the preparation method provided in this application.

[0027] Figure 2 This is a schematic diagram illustrating the transfer of a microLED chip array onto a temporary carrier to form a light-emitting array unit, as provided in this application.

[0028] Figure 3 For along Figure 2 A cross-sectional view of the dashed line A.

[0029] Figure 4 To be Figure 2A schematic diagram showing the transfer of the light-emitting array unit to the fan-out substrate.

[0030] Figure 5 For along Figure 4 A cross-sectional view of the dashed line B.

[0031] Figure 6 This is a schematic diagram of the process of fanning out the micro-LED chip electrode through redistribution in one embodiment of this application.

[0032] Figure 7 This is a schematic diagram of the process of flip-chip fan-out microLED chip electrodes in one embodiment of this application.

[0033] Figure 8 To be Figure 4 A top view of the splicing module formed by cutting the fan-out light-emitting array unit in the middle.

[0034] Figure 9 This is a schematic diagram of the arrangement of micro-LED chips in a light-emitting array unit in another embodiment of this application.

[0035] Figure 10 This is a cross-sectional schematic diagram of the light-emitting array unit on the fan-out substrate in another embodiment of this application.

[0036] Figure 11 This is a schematic diagram of the splicing module in a micro LED light source module provided in one embodiment of this application.

[0037] Figure 12 This is a schematic diagram of the splicing module in a micro-LED light source module provided in another embodiment of this application.

[0038] Figure 13 This is a schematic diagram of the splicing module in a micro LED light source module provided in another embodiment of this application.

[0039] Figure 14 A schematic diagram of the printing device provided in this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] It should be understood that when describing the structure of a component, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above the other layer or region, or that it contains other layers or regions between it and the other layer or region. Furthermore, if the component is flipped over, that layer or region will be located "below" or "under" the other layer or region.

[0043] This invention provides a micro-LED light source module and its preparation method, as well as an LED printing device. In the micro-LED light source module preparation method, a modularly splicable light source module is formed by integrating mass transfer and fan-out processes. This solves the problems of low utilization rate of compound epitaxial layers and poor electrical connection reliability caused by wire bonding processes in the preparation of micro-LED array light sources in existing printing devices, and achieves low-cost, high-reliability and high-efficiency micro-LED light source module preparation.

[0044] like Figure 1 As shown, the method 1000 for fabricating a micro-LED light source module provided by the present invention includes: First, a substrate is provided, and multiple microLED chips are fabricated on the substrate; Secondly, a fan-out substrate is provided, which has multiple chip receiving areas, each of which is used to receive a number of microLED chips. Next, multiple micro-LED chips are transferred to multiple chip receiving areas, so that the multiple micro-LED chips are rearranged into multiple light-emitting array units on the fan-out substrate, and the multiple light-emitting array units are cut to form corresponding multiple splicing modules, wherein each splicing module has fan-out pads, and the number of fan-out pads is less than the number of chip electrodes in each light-emitting array unit; and Finally, a carrier substrate is provided, which includes a splicing area and multiple pad electrodes. Multiple splicing modules are fixed in the splicing area and electrically connected to multiple fan-out pads and multiple pad electrodes to obtain a micro LED light source module.

[0045] The following will combine Figure 2 To the diagram Figure 8 Detailed description Figure 1 Method for fabricating a micro-LED light source module 1000.

[0046] First, a substrate 10 is provided, on which a plurality of micro-LED chips are fabricated. The substrate 10 is, for example, a sapphire substrate or a gallium arsenide substrate. The micro-LED chips fabricated on the sapphire substrate are blue and green LED chips, and the micro-LED chips fabricated on the gallium arsenide substrate are yellow and red micro-LED chips.

[0047] For example, a compound epitaxial layer is fabricated on a sapphire substrate, including the sequential growth of N-type gallium nitride, a quantum well light-emitting layer, and P-type gallium nitride. A light-emitting structure is formed by semiconductor processes such as cleaning and photolithography / etching of the compound epitaxial layer. Finally, P-contact electrodes and N-contact electrodes, respectively contacting P-type or N-type gallium nitride, are deposited to form blue and green micro-LED chips. The emission wavelength of the micro-LED chips in this application covers 200-1000 nm, with common wavelengths used for 3D printing including 365 nm, 385 nm, and 405 nm, and for 2D printing including 765 nm and 780 nm.

[0048] It is understandable that yellow and red light micro-LED chips are typically fabricated on gallium arsenide (GaAs) substrates by preparing compound epitaxial layers, including sequentially growing N-type aluminum gallium indium phosphide (AlGaInP), quantum wells, and P-type AlGaInP. Since GaAs substrates are not conducive to mass transfer, the semiconductor thin film can be transferred from the GaAs substrate to a sapphire substrate before semiconductor processing. For example, a sacrificial layer can be pre-prepared on the GaAs substrate, and a compound epitaxial layer can be prepared on the sacrificial layer. The GaAs substrate and the sapphire substrate are then bonded by wafer bonding, and the compound epitaxial layer is separated from the sacrificial layer and transferred to the sapphire substrate by laser lift-off. Semiconductor processing is then performed on the transferred sapphire substrate to form a light-emitting structure, and finally, P-contact electrodes and N-contact electrodes that contact P-type or N-type gallium nitride are formed to obtain red and yellow light micro-LED chips.

[0049] like Figure 2As shown, multiple microLED chips 11 are arrayed on the substrate 10. Each microLED chip has a size of 5*5μm to 100*100μm, and the spacing between two microLED chips is 1-10μm. The microLED chips 11 are passivated with silicon oxide. In some schemes, a reflective layer is also pre-set on P-type gallium nitride or N-type aluminum gallium indium phosphide. The reflective layer is, for example, a distributed Bragg mirror (DBR), a metal Al or Ag reflective layer.

[0050] In order to meet the requirements of the micro-LED light source module fabrication method 100 of this application, the micro-LED chip 11 can preferably be a square-shaped micro-LED chip or a vertical-shaped micro-LED chip.

[0051] Continue to refer to Figures 2 to 4 A fan-out substrate 30 is provided, on which a plurality of chip receiving areas 31 are provided, and each chip receiving area 31 is used to receive a number of micro LED chips 11.

[0052] The substrate 10 can also be regarded as a growth substrate. There is an initial spacing between any two micro LED chips 11 on it. Before being transferred to the fan-out substrate 30, the micro LED chips 11 on the substrate 10 are transferred to the intermediate carrier 20 using the intermediate carrier 20 and the mass transfer process. The micro LED chips 11 transferred to the intermediate carrier 20 have a preset spacing between them. The preset spacing is usually larger than the initial spacing, mainly to provide operability for the subsequent electrical interconnection process.

[0053] like Figure 2 and Figure 3 As shown, the intermediate carrier 20 has a patterned transfer layer 21 pre-set on it. The pickup units on the patterned transfer layer 21 have a preset spacing. The substrate 10 and the intermediate carrier 20 are bonded together. By selectively lifting with a laser, the microLED chips on the substrate 10 are selectively transferred to the patterned transfer layer 21. It is understood that the transfer substrate 20 and the patterned transfer layer 21 thereon are only used for explanation and illustration. This is a pre-processing step before transferring the microLED chips 11 on the substrate 10 to the fan-out substrate 30. It can be adjusted according to the actual process requirements. For example, multiple intermediate carriers 20 can be provided for multiple transfers to obtain a microLED chip array with a preset spacing.

[0054] like Figure 4 and Figure 5 As shown, a bonding transfer substrate 20 and a fan-out substrate 30 are bonded. A laser irradiates one side of the transfer substrate 20, peeling the micro LED chip 11 off from the transfer layer 21. The micro LED chip 11 is transferred to the chip receiving area 31 of the fan-out substrate 30. The spacing between several micro LED chips 11 in the chip receiving area 31 is a preset spacing.

[0055] In this embodiment, the process of transferring the microLED chip 11 on the substrate 10 to the chip receiving area 31 of the fan-out substrate 30 is described using a standard microLED chip 11 as an example. In other embodiments of this application, when the microLED chip has a flip-chip or vertical structure, the above transfer process can be adaptively adjusted based on the change in chip structure. The purpose of the adaptive adjustment is to achieve electrical interconnection after subsequent fan-out.

[0056] Continue to refer to Figure 4 and Figure 5 Multiple microLED chips 11 transferred to the chip receiving area 31 are arranged at a preset spacing and rearranged into a light-emitting array unit on the fan-out substrate 30. In other words, each light-emitting array unit includes multiple microLED chips 11 arranged at a preset spacing. Subsequently, by performing a fan-out process on the light-emitting array unit, the size of the fan-out pads (electrodes) for electrical interconnection is increased and the number is reduced, thereby changing the problems of high operational difficulty and low electrical stability caused by the need for electrical interconnection of the P / N contact electrodes of individual microLED chips 11 in the existing microLED light source module manufacturing process.

[0057] like Figure 10 As shown, in a preferred embodiment of this application, the fan-out substrate 30 is, for example, a silicon wafer, sapphire, quartz, ceramic, etc. A reflective layer 32 may be pre-set in the chip receiving area 31. The reflective layer 32 is used to reflect the light emitted from the microLED chip towards the fan-out substrate 30, thereby increasing the luminous efficiency of the microLED chip. When the reflective layer 32 is a metal reflective layer, an insulating layer is provided between the metal reflective layer and the microLED chip structure to prevent short circuits due to electrical connection issues. The reflection spectrum of the reflective layer 32 is defined according to the wavelength of the microLED chip: 200-1000nm, and the reflectivity is between 70% and 100%.

[0058] like Figure 10 As shown, in the light-emitting array unit, light-blocking barriers 36 are set between the micro-LED chips 11 to avoid light crosstalk, thereby improving the light output effect and meeting the requirements of high-resolution printing equipment.

[0059] In addition, to increase the structural strength of the light-emitting array unit, a transparent protective layer 37 is provided. The transparent protective layer 37 is formed by coating a transparent protective adhesive. The adhesive needs to have a transmittance of more than 90% for the emission wavelength of the micro-LED. Furthermore, the pad areas for electrical interconnection on the fan-out substrate 30 are not provided with a transparent protective layer.

[0060] Furthermore, in other embodiments of this application, each microLED chip in the light-emitting array unit is provided with a microlens to converge and focus the emission angle for accurate imaging on the photosensitive drum of the printing device. Additionally, the microlens can be made of inorganic or organic material and are formed using a photolithography process.

[0061] In this embodiment, multiple micro-LED chips 11 in the light-emitting array unit are arranged linearly at equal intervals along the row and column directions, but this is not a limitation. For example Figure 9 As shown, in another embodiment of this application, multiple microLED chips 11 in the light-emitting array unit form multiple first minimum repeating units, and the multiple first minimum repeating units are arranged at equal intervals along the row direction or column direction.

[0062] like Figure 6 and Figure 7 As shown, in this application, there are two ways to place the microLED chip 11 in the chip region 31 by mass transfer. The figure is illustrated with a cross-sectional structure diagram, which is only for illustration and does not represent the actual film structure.

[0063] like Figure 6 As shown, the fan-out substrate 30 is a glass substrate, and no circuit structure is preset on the glass substrate before receiving the micro LED chip 11.

[0064] Combination Figure 4 and Figure 8 As shown, after the microLED chip is transferred to the chip receiving area 31, a molding compound 50 is formed on the fan-out substrate 30. The patterned molding compound 50 exposes the chip electrodes of the microLED chip 11, including: N-type contact electrodes 111 and P-type contact electrodes 112. Fan-out lines 35 and first fan-out pads 33 and second fan-out pads 34 are formed in the area of ​​the molding compound 50 outside the chip receiving area 31. The fan-out lines 35 and fan-out pads 34 are electrically connected. The fan-out lines 35 are electrically connected to the N-type contact electrodes 111 and P-type contact electrodes 112 through first connecting electrodes 341 and second connecting electrodes 331, respectively. The number of first fan-out pads 33 and second fan-out pads 34 is less than the number of N-type contact electrodes 111 and P-type contact electrodes 112, respectively. The number of first connecting electrodes 341 and second connecting electrodes 331 is also less than the number of N-type contact electrodes 111 and P-type contact electrodes 112, respectively.

[0065] Optionally, the chip electrodes of the microLED chip are electrically connected on the molding layer 50 through a redistribution layer, and the fan-out line 35 and the first fan-out pad 33 and the second fan-out pad 34 are connected through the first connection electrode 341 and the second connection electrode 331.

[0066] like Figure 7 As shown in another embodiment of this application, this is a schematic diagram illustrating the process of fan-out and electrical connection of the electrodes of the microLED chip 11 on the fan-out substrate 30. This embodiment is applicable to the schematic diagram of the microLED chip 11 being fan-out via flip-chip bonding to the fan-out substrate 30.

[0067] In this embodiment, a fan-out line 35 and corresponding first fan-out pads 33 and second fan-out pads 34 are pre-set on the outer side of the chip receiving area 31 of the fan-out substrate 30. A receiving electrode 38 is pre-set in the chip receiving area 31. The receiving electrode 38 can be flip-chip bonded to the P-type contact electrode 112 and N-type contact electrode 111 of the microLED chip 11. The number of receiving electrodes 38 is equal to the number of P-type contact electrodes 112 and N-type contact electrodes 111. Specifically, the P-type contact electrode 112 and N-type contact electrode 111 of the microLED chip 11 are electrically and mechanically connected to the corresponding receiving electrode 38 on the fan-out substrate 30 through bumps (such as gold bumps, tin bumps, etc.) or eutectic bonding (such as gold-tin alloy).

[0068] like Figure 2 and Figure 7 As shown, the temporary carrier 20 temporarily fixes the micro LED chip 11 through the transfer layer 21. Taking the upright micro LED chip 11 as an example, the chip electrode of the micro LED chip 11 is temporarily fixed in the transfer layer 21. In order to enable the micro LED chip 11 to be electrically connected to the fan-out substrate 30, another transition carrier 50 is provided. The transition carrier 50 is provided with a patterned transition transfer layer 51. The transition carrier 50 and the temporary carrier 20 are bonded together. The temporary carrier 20 is irradiated with a laser to transfer the micro LED chip 11 from the temporary carrier 20 to the transition carrier 50. The chip electrode of the micro LED chip 11 is exposed. The micro LED chip 11 is then electrically connected to the receiving electrode 38 in the chip receiving area 31 of the fan-out substrate 30 by flip-chip bonding.

[0069] The above Figure 6 and Figure 7 In the process, the size of the first fan-out pad 33 and the second fan-out pad 34 is greater than 40μm and the spacing is greater than 40μm. The pads can be coplanar with the micro LED chip 11, or through a through hole can be formed on the fan-out substrate 30 by the TSV process, so that the first fan-out pad 33, the second fan-out pad 34 and the micro LED chip are not on the same plane.

[0070] like Figure 8 As shown, Figure 4 Some of the light-emitting array units in the middle are... Figure 6 or Figure 7 In the process flow, after the fan-out substrate 30 is fanned out, it is cut along the preset cutting street on the fan-out substrate 30 to form a single splicing module 40. Figure 8 The fan-out pad arrangement logic of this application is illustrated only by taking part of the fan-out pads and fan-out lines of the micro-LED chips 11 in the light-emitting array unit as an example.

[0071] In this application, it is assumed that the entire micro-LED light source module requires A number of micro-LED chips, each splicing module 40 contains B number of micro-LED chips, and the number of splicing modules 40 is H, where A = B * H.

[0072] Reference Figure 8 In the splicing module 40, the number B micro-LED chips are divided into C light-emitting sub-units 41, and each light-emitting sub-unit 41 contains N micro-LED chips. Figure 8 The number of light-emitting sub-units 41 and the number of micro-LED chips 11 contained therein shown are only for illustrating the arrangement logic of the fan-out line 35 and the first fan-out pad 33 and the second fan-out pad 34. This number does not limit the actual number of light-emitting sub-units 41 and the number of micro-LED chips 11 contained therein in the splicing module 40 produced.

[0073] by Figure 8 For example, the splicing module 40 includes three light-emitting sub-units 41, each of which includes four micro-LED chips. The four micro-LED chips 11 adopt a common cathode structure, that is, the N-type electrodes 111 of the four LED chips 11 are commonly electrically connected to a first connecting electrode 341 (common cathode connecting electrode) on one side, and the first connecting electrode 341 is then connected via a second fan-out pad 34 (common cathode fan-out pad). Optionally, in other embodiments of this application, the N number of micro-LED chips in each light-emitting sub-unit may adopt a common anode structure, that is, the P-type electrodes of the N number of micro-LED chips are commonly electrically connected to a common anode connecting electrode on one side, and the common anode connecting electrode is then electrically connected via a common anode fan-out pad.

[0074] Furthermore, when each light-emitting sub-unit 41 adopts a common cathode structure, the C number of light-emitting units 41 have the same number of second fan-out pads 34, that is, the number of second fan-out pads 34 is C. Optionally, in other embodiments of this application, when each light-emitting sub-unit adopts a common anode structure, the C number of light-emitting units have the same number of common anode fan-out pads, that is, the number of common anode fan-out pads is C.

[0075] Continue to refer to Figure 8 Each light-emitting subunit 41 adopts a common cathode structure. The P-type electrodes 112 of the four (number N) micro-LED chips 11 in each light-emitting subunit 41 are electrically connected to the corresponding first fan-out pads 33 (anode fan-out pads) via fan-out lines 35 and second connecting electrodes 331 (common anode connecting electrodes). In this embodiment, there are four fan-out lines 35 and four first fan-out pads 33.

[0076] In the printing equipment, each microLED chip 11 in the microLED array light source module formed by splicing multiple splicing modules 40 needs to be individually driven and lit. For each microLED chip 11 to be lit, it needs to simultaneously receive electrical signals through its corresponding N-type contact electrode 111 and P-type contact electrode 112. Figure 8 The arrangement of each microLED chip 11 in the illustrated light-emitting subunit 41 illustrates the individual driving light-emitting logic.

[0077] Specifically, the anode electrical signal is input through the first anode fan-out pad 33a and flows into the P-type contact electrode 112 through the first fan-out line 35a, and the cathode electrical signal is input through the first cathode fan-out pad 34a and flows into the N-type contact electrode 111. At this time, the first micro-LED chip 11 in the light-emitting sub-unit 41 is lit.

[0078] Similarly, when it is necessary to drive the second, third, and fourth microLED chips in the first light-emitting subunit 41 in the row direction, electrical signals can be sequentially and independently input through the second anode fan-out pad 33b, the third anode fan-out pad 33c, and the fourth anode fan-out pad 33d, and then flow into the P-type contact electrodes 112 of the corresponding second, third, and fourth microLED chips 11 via the corresponding second fan-out line 35b, the third fan-out line 35c, and the fourth fan-out line 35d, thereby enabling each microLED chip 11 in the first light-emitting subunit 41 to be lit sequentially. Optionally, in other embodiments of this application, the first to fourth microLED chips can also be selectively lit according to the photosensitive pattern requirements.

[0079] in, Figure 8The driving method of each microLED chip 11 in the second and third light-emitting sub-units 41 in the row direction is the same as that of each microLED chip 11 in the first light-emitting sub-unit 41. The difference is that lighting up each microLED chip 11 in the second light-emitting sub-unit 41 requires inputting a cathode driving signal from the second cathode fan-out pad 34b; lighting up each microLED chip 11 in the third light-emitting sub-unit 41 requires inputting a cathode driving signal from the third cathode fan-out pad 34c. In this application, each first fan-out pad 33 is configured to independently provide driving electrical signals to the microLED chips 11 located in the same sequence position in the C light-emitting sub-units 41, so that each microLED chip 11 can be addressed and lit independently. In this context, "identical sequence" refers to the first micro-LED chip 11 in the first light-emitting sub-unit 41, the first micro-LED chip 11 in the second light-emitting sub-unit 41, and the first micro-LED chip 11 in the third light-emitting power supply 41 in the row direction. These three first micro-LED chips 11 are respectively connected to the first fan-out line 35a through a P-type contact electrode 112, and then electrically connected to the first anode fan-out pad 33a through a first connection electrode 331. The anode drive signal driving these three first micro-LED chips 11 is input from the first anode fan-out pad 33a. At the same time, the cathode drive signal is input from the corresponding first, second, and third cathode fan-out pads 34a, 34b, and 34c in the common cathode structure, so that the three first micro-LED chips can be lit independently.

[0080] in addition, Figure 8 In the splicing module 40 shown in the diagram, three light-emitting sub-units 41 share a fan-out line 35. It is understood that in the fabrication of the micro-LED array light source module, the actual number C of light-emitting sub-units 41 in each splicing module 40 is significantly greater than 3, and the actual number N of micro-LED chips 11 in each light-emitting sub-unit 41 is significantly greater than 4. Considering that the fan-out line 35 is usually made of metal, its resistance increases with length, which can easily cause signal delay and obstruction during long-distance transmission of electrical signals on the fan-out line 35. Optionally, multiple sets of fan-out lines 35 can be set near the light-emitting sub-units 41. Specifically, C light-emitting sub-units 41 are reorganized into M light-emitting parent units 42, where M ≤ C. Each light-emitting parent unit 42 shares a set of fan-out lines 35, and the number of lines in each set of fan-out lines 35 is the same as the number N of micro-LED chips in each light-emitting sub-unit 41 (or, in a common cathode structure, the number of fan-out lines is equal to the number of anode electrodes of the micro-LED chips in the light-emitting sub-unit). Correspondingly, each parent light-emitting unit 42 can share a set of first fan-out pads 33, and the number of first fan-out pads 33 is the same as the number N of micro-LED chips in each child light-emitting unit 41.

[0081] Combination Figure 8As can be seen, in this application, the fan-out logic of the fan-out line 35 and the first fan-out pad 33 and the second fan-out pad 34 can be summarized as follows: When the light-emitting sub-unit 41 adopts a common cathode structure or a common anode structure, the second fan-out pad 34, as a common cathode pad or a common anode pad, is configured to provide cathode or anode electrical signal input to each light-emitting sub-unit 41 as a whole. Therefore, the number of second fan-out pads 34 is equal to the number of light-emitting sub-units 41, C. The first fan-out pad 33 is configured to provide opposite anode or cathode driving electrical signal input to each micro-LED chip 11 in each light-emitting sub-unit 41. Therefore, the number of first fan-out pads 33 is equal to the number of each micro-LED chip 11 in each light-emitting sub-unit 41, N. Since C light-emitting sub-units 41 are recombined into M light-emitting parent units 42, and each light-emitting parent unit 42 shares N first fan-out pads 33, the total number of first fan-out pads 33 in each splicing module 40 is M*N. In addition, each light-emitting parent unit 42 shares a set of fan-out lines 35. The number of fan-out lines 35 is the same as the number of first fan-out pads 33, so that the first fan-out pads 33 provide driving signals to the micro LED chips 11 in all light-emitting sub-units 41 of each light-emitting parent unit 42.

[0082] In this application, a light-emitting array unit composed of multiple micro-LED chips 11 is divided into M parent light-emitting units 42. Each parent light-emitting unit 42 includes at least one child light-emitting unit 41, and each child light-emitting unit includes N micro-LED chips 11. Each parent light-emitting unit 42 shares a set of first fan-out pads 33. By sharing the first fan-out pads 33 and using second fan-out pads 34 with common cathode or common anode structures for each child light-emitting unit 41, the physical size of the electrodes on the multiple micro-LED chips 11 in the light-emitting array unit is "enlarged" by the first fan-out pads 33 and the second fan-out pads 34. At the same time, the number of P-type contact electrodes 112 and N-type contact electrodes 111 of the micro-LED chips 11 is significantly reduced. The large size and significantly reduced number of the first fan-out pads 33 and the second fan-out pads 34 provide a basis for reliable interconnection of the pad electrodes between the subsequent splicing module 40 and the circuit board 60.

[0083] Figures 11 to 13 Different splicing arrangements of multiple splicing modules 40 mounted on the carrier substrate 60 are illustrated.

[0084] like Figure 11As shown, multiple splicing modules 40 are arranged in a stepped manner within the splicing area 61 of the carrier substrate 60, with equal spacing along the row direction but staggered along the column direction. The splicing modules 40 are then fixed sequentially within these elongated splicing areas 61. This arrangement can integrate longer effective light-emitting line segments through multi-level stepped splicing without significantly increasing the width of a single carrier board, making it suitable for linear printheads that require ultra-large format or longer scanning width. Furthermore, the carrier substrate 60 is provided with a driving chip unit 62 to drive each splicing module 40. Alignment marks 63 are provided on the carrier substrate 60, providing a reference for the accurate mounting of the splicing modules 40 within the splicing area 61.

[0085] like Figure 12 As shown, multiple splicing modules 40 are arranged linearly at equal intervals along the row direction on the carrier substrate 60.

[0086] like Figure 13 As shown, multiple splicing modules 40 form a second minimum repeating unit on the carrier substrate 60, and these second minimum repeating units are then arranged at equal intervals along the row or column direction. The second minimum repeating unit can be four splicing modules 40 in the row direction or two splicing modules in the column direction.

[0087] In all the splicing embodiments above, the splicing module 40 is fixed to the carrier substrate 60 by a fixing adhesive layer (such as silver paste with good thermal conductivity, silicone adhesive, or transparent optical adhesive with high light transmittance).

[0088] The fan-out pads 34 and 33 of the splicing module 40 and the corresponding driving chip units 62 on the carrier substrate 60 can be electrically connected by wire bonding (when the pads and the micro LED chip 11 are on the same side of the fan-out substrate 30) or flip-chip bonding (when the pads and the micro LED chip 11 are on opposite sides of the fan-out substrate 30).

[0089] In addition, the carrier substrate 60 also integrates the driver chip 63 and other necessary passive components such as capacitors and resistors. These components are usually mounted in the non-light-emitting area or back of the substrate through SMT (surface mount technology) or flip-chip bonding process, thereby effectively isolating them from the light-emitting unit in terms of physical and thermal properties, and avoiding the direct negative impact of the heat generated by the driver circuit on the luminous efficiency of the micro LED.

[0090] Multiple splicing modules 40 are mounted on the carrier substrate 60 as follows: Figures 11 to 13 Different arrangements are made to form the micro-LED light source module of this application, wherein the micro-LED light source module is a point light source module.

[0091] like Figure 14As shown, this application also provides a schematic diagram of an LED printing device. The printing device includes at least one micro-LED light source module 100 prepared by the method described in any of the above embodiments. This micro-LED light source module 100 serves as the core exposure light source, emitting high-density, high-uniformity, and high-reliability modulated light. Driven by an internal control circuit (not shown), the printing device scans and exposes the imaging medium according to the image data or slice layer data to be printed.

[0092] For example, in a 2D laser printer architecture, light from the micro-LED light source module 100 is irradiated onto the surface of the photosensitive drum 300 via a lens array 200 to form an electrostatic latent image. In a 3D printer based on reduction polymerization (such as SLA or DLP-like), light selectively cures the resin in the photosensitive resin tank through surface exposure or scanning exposure. The micro-LED light source module 100 provided by this invention, due to its high density, high reliability, and excellent heat dissipation design, can provide an ideal light source solution for next-generation high-speed, high-resolution, and long-life 2D / 3D printing equipment.

[0093] In summary, this invention provides a micro-LED light source module and its fabrication method, as well as an LED printing device. The micro-LED light source module fabrication method includes: In the process of first transferring the micro-LED chips fabricated on the compound wafer to the fan-out substrate to form several light-emitting array units, these micron-sized chips can be transferred and temporarily fixed on the fan-out substrate with high precision in one go. Multiple periodically arranged micro-LED chip light-emitting array units with consistent spacing are formed on the fan-out substrate according to a preset spacing. The pre-formation of micro-LED chips results in high utilization of the compound film. Combined with the mass transfer technology, there is a significant cost advantage. Next, the electrodes of the microLED chips in each light-emitting array unit are fanned out to form fan-out pads, thus enlarging the size of the fan-out pads. The fan-out process achieves "enlargement" of the physical size of the electrodes on the microLED chips and a significant reduction in the number of electrodes (common anode / common cathode fan-out pads, multiple light-emitting sub-units in each parent light-emitting unit of the reorganized light-emitting array unit provide drive signal input by sharing a set of fan-out pads). The large-size fan-out pads provide a foundation for reliable interconnection with the pad electrodes of the circuit board in the future. Finally, the multiple light-emitting array units on the fan-out substrate are cut into multiple splicing modules, which are then spliced ​​onto a circuit board (PCB / TGV) with a driver chip. The fan-out pads and the circuit board pad electrodes are electrically connected. Due to their larger physical size, the splicing modules are easier to install and connect. Furthermore, the driver chip is centrally located on the back of the system circuit board or in a non-light-emitting area, physically separated from the light-emitting micro-LED array. This effectively eliminates the direct "thermal interference" of the driver chip's heat on the micro-LED's luminous efficiency (temperature rise leads to efficiency reduction), improving the overall system's thermal stability and electrical performance.

[0094] The present invention has been described by the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. Furthermore, the technical features involved in the different embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A method for fabricating a micro-LED light source module, characterized in that, The preparation method includes: A substrate is provided, on which a plurality of microLED chips are fabricated; A fan-out substrate is provided, wherein the fan-out substrate is provided with a plurality of chip receiving areas, and each chip receiving area is used to receive a plurality of microLED chips; Multiple microLED chips are transferred to multiple chip receiving areas to rearrange the microLED chips into multiple light-emitting array units on the fan-out substrate, and the multiple light-emitting array units are cut to form corresponding multiple splicing modules, wherein each splicing module has a fan-out pad, and the number of fan-out pads is less than the total number of chip electrodes in each light-emitting array unit; and A carrier substrate is provided, the carrier substrate including a splicing area and multiple pad electrodes, the multiple splicing modules are fixed in the splicing area, and the multiple fan-out pads and multiple pad electrodes are electrically connected to obtain the micro LED light source module.

2. The preparation method according to claim 1, characterized in that, The fan-out substrate has a pre-set fan-out line and a plurality of fan-out pads, and the fan-out line and fan-out pads are located outside the receiving area of ​​each chip.

3. The preparation method according to claim 1, characterized in that, The fan-out substrate does not have pre-set fan-out lines and multiple fan-out pads, and also includes: A molding compound is formed on the fan-out substrate, the molding compound covering the plurality of microLED chips, and the chip electrode of each microLED chip is exposed from the molding compound; The fan-out lines and the plurality of fan-out pads are electrically connected on the molding compound; and Multiple connection electrodes are formed on the molding layer. The multiple connection electrodes are electrically connected to the corresponding fan-out line and the chip electrode of the corresponding micro LED chip. The number of connection electrodes is less than the total number of chip electrodes in each corresponding light-emitting array unit.

4. The preparation method according to claim 2 or 3, characterized in that, The multiple fan-out pads and the chip electrodes of the multiple microLED chips are located on the same side of the fan-out substrate, or the multiple fan-out pads and the corresponding chip electrodes of the multiple microLED chips are located on opposite sides of the fan-out substrate.

5. In the preparation method according to claim 4, the characteristic is that, When the chip electrodes of the multiple fan-out pads and the multiple microLED chips are located on the same side of the fan-out substrate, wire bonding is performed to connect the multiple chip electrodes and the multiple fan-out pads. When the multiple fan-out pads and the corresponding chip electrodes of the multiple microLED chips are located on opposite sides of the fan-out substrate, the multiple chip electrodes and the multiple fan-out pads are flip-chip bonded.

6. The preparation method according to claim 1, characterized in that, Also includes: A reflective layer is formed in one or more of the chip receiving regions.

7. The preparation method according to claim 1, characterized in that, Multiple microLED chips are transferred to multiple chip receiving areas, and light-blocking barriers are formed between any adjacent microLED chips.

8. The preparation method according to claim 1, characterized in that, Multiple microLED chips are transferred to multiple chip receiving regions, and a microlens structure is fabricated on each microLED chip. The microlens structure is used to converge the emission angle of the microLED chip.

9. The preparation method according to claim 1, characterized in that, Multiple microLED chips are transferred to multiple chip receiving areas, a transparent adhesive layer is prepared on the fan-out substrate, the transparent adhesive layer is patterned, the transparent adhesive layer covers the microLED chips, and the light transmittance of the transparent adhesive layer is >90%.

10. The preparation method according to claim 1, characterized in that, Multiple microLED chips are transferred to multiple chip receiving areas, wherein in each chip receiving area, the multiple microLED chips are linearly arranged at equal intervals along a row or column direction; or... In each of the chip receiving areas, multiple micro-LED chips form multiple first minimum repeating units, and the multiple first minimum repeating units are arranged at equal intervals along the row direction or column direction.

11. The preparation method according to claim 1, characterized in that, The splicing area is a long strip-shaped area preset on the carrier substrate. There are multiple long strip-shaped areas, which are arranged at equal intervals along the row direction and in a stepped manner along the column direction on the carrier substrate.

12. The preparation method according to claim 1, characterized in that, Multiple splicing modules are arranged linearly at equal intervals along the row or column direction on the carrier substrate; or, Multiple splicing modules form multiple second minimum repeating units on the carrier substrate, and the multiple second minimum repeating units are arranged at equal intervals and staggered along the row direction or column direction.

13. The preparation method according to claim 1, characterized in that, Also includes: A fixing adhesive layer is formed between the multiple splicing modules and the carrier substrate.

14. A micro-LED light source module, characterized in that, The microLED light source module is prepared by the method described in any one of claims 1-13.

15. The micro-LED light source module according to claim 14, characterized in that, Multiple microLED chips are recombined into multiple light-emitting array units, each light-emitting array unit is divided into C light-emitting sub-units, each light-emitting sub-unit contains N microLED chips, and the N microLED chips are electrically connected in a common cathode or common anode structure; The splicing module includes fan-out pads, which are provided with a first fan-out pad and a second fan-out pad; the number of second fan-out pads is C, and each second fan-out pad is configured to provide a common electrical signal to a corresponding light-emitting sub-unit as a whole; The number of the first fan-out pads is at least equal to the N microLED chips in one of the light-emitting subunits. Each of the first fan-out pads is configured to independently provide a driving electrical signal to the microLED chips located in the same sequence position in the C light-emitting subunits, so that each microLED chip can be lit independently.

16. The micro-LED light source module according to claim 15, characterized in that, The C light-emitting subunits are recombined into M light-emitting parent units, each of the light-emitting parent units contains at least one of the light-emitting subunits, and M≤C; Each light-emitting parent unit is configured with a set of first fan-out pads. Each set of first fan-out pads is configured to provide driving electrical signals to all light-emitting sub-units within a corresponding light-emitting parent unit, so that each micro-LED chip can be lit independently. The total number of first fan-out pads in each splicing module is M*N.

17. An LED printing device, characterized in that, The printing device includes the micro-LED light source module as described in claims 14-16.

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