Micro LED flexible display screen and preparation method thereof
By directly transferring and encapsulating the film chip on the substrate intermediate, combining inorganic colloid filling and metal interconnection, the problems of complex processes and high costs in the prior art are solved, and the effect of simplified flexible display screen preparation and reduced production costs are achieved. .
Patent Information
- Application Number
- CN202411419366.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-01-10
AI Technical Summary
The preparation process of existing microLED flexible display screens is complex and costly, and requires pre-made small MIP packages, including transferring microLED red, green and blue film chips and performing electrical insulation and metal interconnection and thinning cutting.
By directly transferring the thin film chip to the substrate intermediate to form the substrate intermediate, and depositing a flexible substrate and metal interconnect structure thereon, filling the through holes with inorganic colloids to form the encapsulated colloid, simplifying the preparation of the flexible display screen The process avoids the step of pre-made small packages.
The preparation process of flexible display screens is simplified, production costs are reduced, and the function of directly displaying graphics is realized, avoiding complex packaging steps.
Smart Images
Figure CN119300592A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of flexible displays, and in particular to a microLED flexible display screen and a preparation method thereof. Background Art
[0002] MicroLED display technology has the advantages of high luminous efficiency, high resolution, wide color gamut and long life. It is widely used in large-screen and high-brightness information display, especially in flexible display, and has broad application prospects.
[0003] LED flexible display technology usually replaces the PCB substrate used for hard screens with a polyimide film several tens of microns thick, prepares metal wiring and insulation layers on the polyimide, flips the MIP (MicroLED in Package) small package onto the polyimide, and finally packages it into a flexible display. However, this method requires the pre-production of the MIP small package, and the preparation of the existing MIP small package requires the transfer of a large number of MicroLED red, green, and blue thin film chips on a transparent substrate, and then thinning and cutting them into MIP small packages (pixels) after electrical insulation and metal interconnection. The process is complex and the cost is high. Summary of the invention
[0004] In order to solve the above problems, the present invention proposes a microLED flexible display screen and a preparation method thereof.
[0005] The main contents of the present invention include: A microLED flexible display screen, comprising: a flexible substrate comprising a first surface and a second surface; A plurality of basic light-emitting units are arranged on the second surface; the basic light-emitting units are thin-film chips; A metal interconnection structure, deposited on the first surface; the metal interconnection structure includes row and column leads and electrode lines, and the electrode lines are used to electrically connect the basic light-emitting units and the row and column leads; An encapsulating colloid is arranged on a surface of the basic light-emitting unit away from the second surface; the encapsulating colloid is obtained by removing and polishing a substrate intermediate; The substrate intermediate comprises a substrate main body and a plurality of through holes extending through the substrate main body; after the basic light-emitting units are arranged in the through holes, inorganic colloid is filled in the through holes and cured to obtain the substrate intermediate.
[0006] Preferably, the through hole includes a receiving section and a main body section; the basic light-emitting unit is arranged in the receiving section, and the cross-sectional area of the receiving section is larger than the cross-sectional area of the main body section.
[0007] Preferably, the cross-section of the accommodation section is square; and the cross-section of the main body section is circular.
[0008] Preferably, the side length of the cross section of the accommodation section is 10-80 μm; and the diameter of the cross section of the main body section is 5-40 μm.
[0009] Preferably, the through hole further comprises a connecting section, wherein the connecting section is located between the accommodating section and the main body section, and a longitudinal section of the connecting section is trapezoidal.
[0010] Preferably, the encapsulating colloid is an inorganic colloid filled in the connecting section.
[0011] Preferably, the basic light-emitting unit is a red thin-film chip, a green thin-film chip or a blue thin-film chip.
[0012] The present invention also proposes a method for preparing a flexible microLED display screen, comprising the following steps: S1. Prepare a substrate body, wherein the substrate body comprises a base surface and a light-emitting surface arranged opposite to each other and a plurality of through holes penetrating the base surface and the light-emitting surface; the through holes are used to accommodate a basic light-emitting unit; wherein the basic light-emitting unit is a thin-film chip; S2, flip-mounting the basic light-emitting unit in the first opening of the through hole; the first opening is located on the substrate surface; S3, filling the through hole with an inorganic colloid through the second opening of the through hole, and forming a packaging colloid after curing; wherein the second opening is located on the light emitting surface; S4, depositing a dielectric film on the substrate surface to form a flexible substrate; S5, performing a planarization process on the through hole through the light emitting surface; S6, depositing a metal thin film layer on the flexible substrate to obtain a metal interconnect structure; S7, removing the substrate body, polishing and cutting to obtain a flexible display screen of a required size, wherein the surface of the basic light-emitting unit of the flexible display screen away from the dielectric layer retains the encapsulation colloid of a set thickness.
[0013] Preferably, the material of the flexible substrate is silicon dioxide; in step S5, SOG solution is coated on the light emitting surface to fill the through hole and the gap between the through hole and the basic light emitting unit.
[0014] Preferably, S6 further includes forming a passivation layer on a side of the metal film layer away from the flexible substrate.
[0015] Compared with the prior art, the beneficial effects of the microLED flexible display screen and the preparation method thereof proposed in the present invention are: by first directly transferring a large amount of thin-film chips onto a substrate intermediate to form a substrate intermediate, then depositing a flexible base on the substrate intermediate and performing metal interconnection, and finally performing corresponding processing on the substrate intermediate, graphics can be directly displayed without the need to pre-fabricate a small package, thereby simplifying the preparation process of the flexible display screen and reducing production costs to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a structural schematic diagram of the flexible display screen of the present invention; Figure 2-Figure 5 A schematic diagram of the process for preparing the passivation film of the present invention; Reference numerals: 10-flexible substrate; 11-first surface; 12-second surface; 20-basic light-emitting unit; 20a-red thin film chip; 20b-green thin film chip; 20c-blue thin film chip; 30-metal interconnect structure; 30a-electrode line; 40-substrate body; 400-through hole; 400a-accommodating section; 400b-connecting section; 400c-main section; 50-Encapsulation colloid. DETAILED DESCRIPTION
[0017] The technical solution protected by the present invention is described in detail below with reference to the accompanying drawings.
[0018] The present invention aims to solve the problem that the prior art requires first preparing a MIP small package, and then flip-chip attaching the MIP small package to polyimide to make a flexible display screen, which is complicated and costly. The present invention proposes a microLED flexible display screen, comprising a flexible substrate, a plurality of basic light-emitting units arranged on the flexible substrate, and a metal interconnection structure arranged on the flexible substrate and electrically connected to the plurality of basic light-emitting units; specifically, Figure 1As shown, the flexible substrate 10 includes a first surface 11 and a second surface 12 arranged opposite to each other. Row and column leads and electrode lines 30a electrically connected to the row and column leads and the basic light-emitting units 20 are formed on the first surface 11 by etching grooves, filling or sputtering metal materials on the flexible substrate; some of the basic light-emitting units are existing microLED chips, specifically red thin film chips 20a, green thin film chips 20b and blue thin film chips 20c, and the three thin film chips are arranged in a set array; in other embodiments, other full-color display methods can also be used, such as using only blue microLED chips, replacing green light Micro-LED and red light Micro-LED by making green quantum dots and red quantum dots on blue light Micro-LED. The main purpose of this application is to describe how to prepare a flexible display screen when the MIP small package is not encapsulated, and the solution of using only blue microLED chips will not be elaborated in detail for the time being.
[0019] Furthermore, a packaging colloid 50 is arranged on the side of the basic light-emitting unit 20 away from the second surface 12. The main inventive point of the present invention is how to arrange a plurality of basic light-emitting units on the flexible substrate 10 and how to arrange the packaging colloid 50 on the basic light-emitting units. In the present invention, the packaging colloid 50 is obtained by removing and polishing the substrate intermediate; that is, the inventive point of the present invention is to transfer a plurality of basic light-emitting units to the substrate main body 40 in large quantities, and then form the packaging colloid 50 by referring to the TSV and TGV technology; the structure obtained by arranging the basic light-emitting unit 20 and the packaging colloid 50 on the substrate main body 40 is called a substrate intermediate, such as Figure 2 A schematic diagram is given of opening a through hole 400 on a substrate body 40 by referring to TSV and TGV technologies, and disposing a basic light-emitting unit 20 in the through hole 400. Then, the structure of the substrate intermediate is obtained by filling the through hole 400 with a packaging colloid 50.
[0020] That is, the substrate intermediate includes a substrate body 40 and a plurality of through holes 400 extending through the substrate body 40; after the basic light-emitting unit 20 is arranged in the through hole 400, the through hole 400 is filled with an inorganic colloid and cured to obtain the substrate intermediate; specifically, the substrate body 40 can be made of silicon, sapphire or transparent glass.
[0021] Furthermore, in order to ensure the stability and convenience of the assembly of the basic light-emitting unit 20 and taking into account the subsequent processing steps, the through hole 400 includes a receiving section 400a, a connecting section 400b and a main section 400c from top to bottom; in this embodiment, the cross section of the receiving section 400a is square, and the side length of the cross section is 10-80 μm; the cross section of the main section is circular, and the diameter of the cross section is 5-40 μm; that is, the cross-sectional area of the receiving section 400a is greater than the cross-sectional area of the main section 400c. The longitudinal section of the connecting section 400b is trapezoidal, which is used to receive the receiving section 400a and the main section 400c, and also to control the shape of the encapsulation colloid of a single pixel of the final flexible display screen. The basic light-emitting unit 20 is arranged in the accommodation section 400a. After the encapsulation colloid 50 is filled, for the substrate body 40 made of silicon, the substrate body 40 needs to be removed, and the encapsulation colloid 50 located in the main section 400c is removed at the same time, that is, only the encapsulation colloid 50 located in the connecting section 400b is retained; at the same time, in this embodiment, the encapsulation colloid 50 is an inorganic colloid, which is formed after curing, that is, in this way, the packaging stability of the retained encapsulation colloid 50 and the basic light-emitting unit can also be ensured. Specifically, the substrate body 40 can be thinned to the connection between the main section and the connecting section by thinning treatment, and then the remaining substrate body 40 is removed by polishing and the like, and only the remaining encapsulation colloid 50 is retained.
[0022] In other embodiments, if the substrate body 40 is made of a transparent material such as sapphire or transparent glass, the substrate body 40 may be retained without removal, thereby achieving transparent display.
[0023] Please combine Figures 2 to 5 The following is a detailed introduction to the method for preparing the flexible microLED display screen proposed by the present invention, which includes the following steps: S1. Prepare a substrate body 40, wherein the substrate body 40 comprises a base surface and a light emitting surface which are arranged opposite to each other and a plurality of through holes 400 which penetrate the base surface and the light emitting surface; the through holes 400 are used to accommodate the basic light emitting unit 20; S2, flipping the basic light-emitting unit 20 into the accommodating section 400a of the through hole 400; specifically, using the existing mass transfer technology to assemble a certain number of basic light-emitting units 20 into the through hole 400; S3, filling the through hole with an inorganic colloid through the second opening of the through hole 400, and depositing a dielectric film on the substrate surface to form a flexible substrate, wherein the dielectric film may be made of silicon dioxide; S4, then coating the SOG solution into the through hole 400 from the light-emitting surface of the substrate body 40, so that the SOG solution fills the through hole and the gap between the through hole and the basic light-emitting unit, and then forms a packaging colloid after curing; that is, after the base surface and the light-emitting surface of the substrate body 40 are processed accordingly, the through hole is flattened through the light-emitting surface; S6, then, by etching and patterning the flexible substrate, a metal film layer is deposited to obtain a metal interconnect structure, so as to form corresponding row and column leads and electrode lines; S7, removing the substrate body, polishing and cutting to obtain a flexible display screen of a required size, wherein the surface of the basic light-emitting unit of the flexible display screen away from the dielectric layer retains the encapsulation colloid of a set thickness.
[0024] Wherein, S6 further includes forming a passivation layer on a side of the metal film layer away from the flexible substrate.
[0025] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A microLED flexible display screen, characterized in that: include: a flexible substrate comprising a first surface and a second surface; A plurality of basic light-emitting units are arranged on the second surface; The basic light-emitting unit is a thin-film chip; A metal interconnection structure, deposited on the first surface; the metal interconnection structure includes row and column leads and electrode lines, and the electrode lines are used to electrically connect the basic light-emitting units and the row and column leads; An encapsulating colloid is arranged on a surface of the basic light-emitting unit away from the second surface; the encapsulating colloid is obtained by removing and polishing a substrate intermediate; The substrate intermediate comprises a substrate main body and a plurality of through holes extending through the substrate main body; after the basic light-emitting units are arranged in the through holes, inorganic colloid is filled in the through holes and cured to obtain the substrate intermediate.
2. A microLED flexible display screen according to claim 1, characterized in that: The through hole includes a receiving section and a main body section; the basic light emitting unit is arranged in the receiving section, and the cross-sectional area of the receiving section is larger than the cross-sectional area of the main body section.
3. The microLED flexible display screen according to claim 2, characterized in that: The cross section of the accommodation section is square; the cross section of the main body section is circular.
4. The microLED flexible display screen according to claim 3, characterized in that: The side length of the cross section of the accommodation section is 10-80 μm; the diameter of the cross section of the main body section is 5-40 μm.
5. The microLED flexible display screen according to claim 3, characterized in that: The through hole further comprises a connecting section, wherein the connecting section is located between the accommodating section and the main body section, and a longitudinal section of the connecting section is trapezoidal.
6. The microLED flexible display screen according to claim 5, characterized in that: The encapsulating colloid is an inorganic colloid filled in the connecting section.
7. The microLED flexible display screen according to claim 1, characterized in that: The basic light emitting unit is a red thin film chip, a green thin film chip or a blue thin film chip.
8. A method for preparing a flexible microLED display screen, characterized in that: The steps include: S1. Prepare a substrate body, wherein the substrate body comprises a base surface and a light-emitting surface arranged opposite to each other and a plurality of through holes penetrating the base surface and the light-emitting surface; the through holes are used to accommodate a basic light-emitting unit; wherein the basic light-emitting unit is a thin-film chip; S2, flip-mounting the basic light-emitting unit in the first opening of the through hole; the first opening is located on the substrate surface; S3, filling the through hole with an inorganic colloid through the second opening of the through hole, and forming a packaging colloid after curing; wherein the second opening is located on the light emitting surface; S4, depositing a dielectric film on the substrate surface to form a flexible substrate; S5, performing a planarization process on the through hole through the light emitting surface; S6, depositing a metal thin film layer on the flexible substrate to obtain a metal interconnect structure; S7, removing the substrate body, polishing and cutting to obtain a flexible display screen of a required size, wherein the surface of the basic light-emitting unit of the flexible display screen away from the dielectric layer retains the encapsulation colloid of a set thickness.
9. The method for preparing a flexible microLED display screen according to claim 8, characterized in that: The material of the flexible substrate is silicon dioxide. In step S5, SOG solution is coated on the light emitting surface to fill the through hole and the gap between the through hole and the basic light emitting unit.
10. The method for preparing a flexible microLED display screen according to claim 8, characterized in that: S6 then further includes forming a passivation layer on a side of the metal film layer away from the flexible substrate.