Patent ID: 12218295

DETAILED DESCRIPTION

FIGS.1through8, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system or device.

Hereinafter, various embodiments of the disclosure are described with reference to the accompanying drawings. However, it should be appreciated that this is not intended to limit the technological features set forth herein to particular embodiments and include various changes, equivalents, or replacements for an embodiment of the disclosure. With regard to the description of the drawings, similar reference numerals may be used to refer to similar or related elements.

FIG.1is a cross-sectional view illustrating a structure of a micro Light Emitting Diode (LED) display according to various embodiments of the disclosure.

Referring toFIG.1, a display device10according to an embodiment may be a display device in which a plurality of micro LED chips20are plated, as a display element using a structure in which a plurality of light emitting elements are arrayed on a substrate11. According to an embodiment, the display device10may include the substrate11, a polymer adhesive layer12, and the plurality of micro LED chips20. Hereinafter, the display device10will be referred to as a micro LED display.

According to an embodiment, a plurality of light emitting elements, e.g., the micro LED chips20, are made conductive after plating on the substrate11by means of the polymer adhesive layer12and function as a light source of the display. For example, the micro LED chip20has a size approximately less than or equal to 100 μm, and in general, may have a size of tens of μm. According to an embodiment, the micro LED chip20may include a light emitting body21and a connection pad22. According to an embodiment, one face21aof the light emitting body21is a face from which light is emitted, and the other face21bmay be a face to which the connection pad22is disposed. According to an embodiment, the plurality of micro LED chips20may be arrayed and attached arrayed on the polymer adhesive layer12in a connection pad-down state. According to an embodiment, in each of the plurality of micro LED chips20, a first portion201may be located inside the polymer adhesive layer12on the adhesive layer12, and a second portion202may be located outside the polymer adhesive layer12. According to an embodiment, the micro LED chip20may be disposed such that the connection pad22is located inside the polymer adhesive layer12so as to be connected to metal particles112.

According to an embodiment, the micro LED chip20may be disposed such that the first portion201occupies approximately less than or equal to 50%, and the second portion202occupies greater than or equal to 50%. According to an embodiment, since there is a need for a structure in which the connection pad22is located inside the polymer adhesive layer12, the micro LED chip20may be disposed such that the first portion201occupies less than or equal to 10%, and the second portion202occupies greater than or equal to 90%.

According to an embodiment, the substrate11may be a support base for plating a plurality of electric elements, i.e., the micro LED chips20used as a light emitting element of a display, in an aligned state. For example, the substrate11may be constructed of any one of a glass material, a sapphire material, a transparent synthetic resin, and a transparent ceramic material. According to an embodiment, the substrate11may be constructed of a rigid material or a flexible material. According to an embodiment, the substrate11may have a circuit portion110constructed of a conductive material on one face to which the micro LED chips20are connected. For example, the circuit portion110may be a Thin Film Transistor (TFT) circuit. According to an embodiment, the circuit portion110may be disposed to one face of the substrate11in a layer shape. According to an embodiment, the circuit portion110may be disposed in a protruding shape or a recessed shape on one face of the substrate11.

According to an embodiment, the polymer adhesive layer12may be constructed on one face of the substrate11. According to an embodiment, the polymer adhesive layer12is a layer cured after coating an adhesive solution on one face11aof the substrate11, and may include the plurality of metal particles112dispersed with each other. The metal particles112may have a nano size approximately in the range of 50 nm to 500 nm. According to an embodiment, the metal particles112may be disposed inside the polymer adhesive layer12in a uniform or non-uniform state. According to an embodiment, at least one or more of the metal particles112may have a conductive structure for electrically connecting the connection pad22of the micro LED chip and the circuit portion110of the substrate11. For example, the metal particle112may have a size in the range of 50 nm to 500 nm. According to an embodiment, the polymer adhesive layer12coated on the substrate11may be coated with a thickness in the range of 100 nm to 1000 nm.

According to an embodiment, the polymer adhesive layer12may be a support structure for supporting each of the arrayed micro LED chips20, and since the plurality of metal particles112are included, may be part of a conductive structure for electrically connecting the micro LED chip20to the circuit portion110of the substrate11.

According to an embodiment, the micro LED display10may have a conductive structure of the micro LED chip20due to a connection structure between the connection pad22of the micro LED chip20, the plurality of metal particles112, and the circuit portion110of the substrate11.

FIG.2is a cross-sectional view illustrating an annealing process of a micro LED display according to various embodiments of the disclosure.

Referring toFIG.2, according to an embodiment, a micro LED chip20arrayed on a polymer adhesive layer12may be subjected to a heating and pressing process to construct a conductive structure between a substrate11and a connection pad22of the micro LED chip20. According to an embodiment, as shown inFIG.2(a), the plurality of micro LED chips20plated on the polymer adhesive layer12physically bonded may be subjected to the heating and processing process through a chemical reaction to construct a conductive structure between a circuit portion110of the substrate11and the connection pad22of the micro LED chip20.

According to an embodiment, the polymer adhesive layer12including a metal particle112disposed on the substrate11may be subjected to the heating or pressing process to form a physical bond, i.e., a conductive structure, between the metal particle112and the connection pad22of the micro LED chip20. In addition, the physical bond, i.e., the conductive structure, may be formed between the metal particle112and the circuit portion110of the substrate11. The conductive structure may be constructed between the connection pad22of the micro LED chip20and the metal particle112and the circuit portion110of the substrate11due to the physical bond formed around the metal particle112. According to such a process, the plurality of micro LED chips20may be bonded on the substrate11.

According to an embodiment, a micro LED display may be cooled after a chemical bond is achieved through an annealing process in an atmosphere state or an inert gas environment. After the annealing process, the conductive structure of the micro LED chip20for which the chemical bond is achieved is cured. Through the metal particle112, the connection pad22may be electrically connected to the circuit board110more reliably and stably than before the annealing process.

FIG.3AtoFIG.3Dare cross-sectional views sequentially illustrating a manufacturing process of a micro LED display according to various embodiments of the disclosure.

A method of manufacturing a micro LED display according to an embodiment will be described below with reference toFIG.3AtoFIG.3D.

Referring toFIG.3A, a polymer adhesive solution13in which a metal particle112is dispersed on a prepared substrate11may be coated with a first thickness. For example, the first thickness may be a sufficiently thin thickness. According to an embodiment, the first thickness of the polymer adhesive solution13may be in the range of 100 nm to 1000 m. According to an embodiment, in a coating method of the polymer adhesive solution13, large-area coating may use a spin coating method due to a low viscosity of the adhesive solution13, and local coating may use a printing or jetting method. For example, the polymer adhesive solution13may have an adhesive strength of at least 1 Mn/m2. According to an embodiment, the polymer adhesive solution13may contain a UV curing agent. When UV rays are irradiated to the polymer adhesive solution13, the adhesive strength of the irradiated portion may be removed.

According to an embodiment, the plurality of metal particles112contained in the polymer adhesive solution13coated on the substrates11and10are arrayed uniformly or non-uniformly, and may be arrayed on a circuit portion110of the substrates11and10. According to an embodiment, the plurality of metal particles112contained in the polymer adhesive solution13may have a nano size, for example, in the range of 50 nm to 500 nm. According to an embodiment, the metal particles112contained in the polymer adhesive solution13are alloyed with metal materials in the circuit portion110of the substrates11and10at a temperature in the range of 50° C. to 300° C., or may have a melting point at a temperature equal to or lower than that.

A plurality of micro-sized electronic elements, such as a plurality of micro LED chips20, prepared on the substrates11and10coated with the polymer adhesive solution13may be prepared at a desired position. According to an embodiment, in each of the micro LED chips20, a connection pad may be located on the polymer adhesive solution13in a connection pad-down state. For example, the micro LED chip20may have a size in the range of 10 μm to 100 μm, and may be generally constructed to have a size of tens of μm.

Referring toFIG.3B, according to an embodiment, the plurality of arrayed micro LED chips20may be attached by falling on the coated polymer adhesive solution13by their own weight. According to an embodiment, since the viscosity of the liquid polymer adhesive solution13is low, the micro LED chip20may gradually descend from an upper face of the polymer adhesive solution13by its own weight, heating, and pressure.

Referring toFIG.3C, according to an embodiment, the plurality of micro LED chips20descending by a first distance may have a space in which the metal particle112and a connection pad22are partially spaced apart from each other when energy is applied to the polymer adhesive solution13by heating (simple heat treatment at a temperature approximately less than or equal to 100° C.) and pressing (low pressure less than or equal to 1 N/m2) in an atmosphere state.

Referring toFIG.3D, through a continuous heating and pressing process of the polymer adhesive solution13, the circuit portion110of the substrate11, the metal particle112, and the connection pad22may be physically bonded, that is, electrically connected. According to an embodiment, the UV curable polymer adhesive solution13may be used to remove adhesion except for a desired portion. Since a chemical bond is achieved between the circuit portion110of the substrate11and a pad of an electronic element through the heating and pressing process performed between the substrate11and the micro LED chip20which are physically connected, a more stable and reliable bonding and conductive structure can be constructed between the micro LED chip20and the substrate11.

The micro LED chip20in this state may be cooled through an annealing process in the atmosphere state. After the annealing process, the conductive structure of the micro LED chip20for which the chemical bond is achieved may be cured, and the connection pad22may be stably electrically connected to the circuit portion110through the metal particles112.

FIG.4is a cross-sectional view illustrating a partial structure of a micro LED display10according to various embodiments of the disclosure.

Referring toFIG.4, a bonding structure between a micro LED chip20and a substrate11is different from the bonding structure between the micro LED chip20and the substrate11shown inFIG.1in terms of only a conductive structure between a connection pad22and a circuit portion110, and the remaining structures are identical. Therefore, the identical structure will be omitted to avoid redundancy, and only different structures will be described.

According to an embodiment, the micro LED chip20and the circuit portion110of the substrate11may be electrically connected by a 3-dimensional conductive structure30. According to an embodiment, the circuit portion110may be disposed on one face of the substrate11, and the 3-dimensional conductive structure30may be disposed on one face of the circuit portion110. According to an embodiment, the 3-dimensional conductive structure30may be constructed on the substrate11in a layer shape. For example, the 3-dimensional conductive structure30may be a plating layer containing a metal element such as indium or gold. According to an embodiment, the 3-dimensional conductive structure30may be constructed repeatedly by alternating a ridge portion and a valley portion. For example, the circuit portion110may be a TFT circuit.

According to an embodiment, a polymer adhesive layer12disposed on the circuit portion110of the substrate11is a support structure for supporting the plurality of arrayed micro LED chips20, and may be constructed of an insulating material. According to an embodiment, the polymer adhesive layer12is a solution having a low viscosity before being cured, and the plurality of arrayed micro LED chips20may descend by a specific distance through heating, pressing, and their own weight and then may be physically in contact with a peak of a ridge portion of the 3-dimentional conductive structure30. Subsequently, through a cold welding process of forming a metal-metal bond through additional pressing, the arrayed connection pads22and the peak may be chemically bonded to construct a stable conductive structure.

According to an embodiment, a height h0of the 3-dimensional conductive structure30may be less than or equal to 5 μm, and a length11thereof may be less than or equal to 30 μm. For example, the height h0of the 3-dimensional conductive structure30may be a height from a bottom to the peak of the ridge portion, and the length11of the 3-dimensional conductive structure30may be a width from the peak of the ridge portion to a next peak of a next adjacent ridge portion. Subsequently, after the cold welding performed between the connection pad22and the peak, the connection pad22and the peak are chemically bonded to complete a conductive structure and bonding between the micro LED chip20and the substrate11.

FIG.5AtoFIG.5Dare cross-sectional views sequentially illustrating a manufacturing process of a micro LED display according to various embodiments of the disclosure.

A method of manufacturing a micro LED display will be described as follows according to an embodiment with reference toFIG.5AtoFIG.5D.

Referring toFIG.5A, a substrate11having a circuit portion constructed on one face thereof may be prepared. A 3-dimensional conductive structure may be constructed on the prepared substrate. According to an embodiment, the 3-dimensional conductive structure may have a convex-concave shape, for example, may have a shape in which a ridge portion and a valley portion are constructed alternately. The ridge portion and the valley portion may be constructed on the circuit portion.

According to an embodiment, after the 3-dimensional conductive structure is constructed on the substrate, a polymer adhesive solution13may be coated with a first thickness. For example, the first thickness of the polymer adhesive solution13may be in the range of 100 nm to 1000 m. According to an embodiment, in a coating method of the polymer adhesive solution13, large-area coating may use a spin coating method due to a low viscosity of the adhesive solution13, and local coating may use a printing or jetting method. For example, the polymer adhesive solution13may have an adhesive strength of at least 1 Mn/m2. According to an embodiment, the polymer adhesive solution13may contain a UV curing agent. When UV rays are irradiated to the polymer adhesive solution13, the adhesive strength of the irradiated portion may be removed.

A plurality of micro-sized electronic elements, such as a plurality of micro LED chips20, prepared on the substrate11coated with the polymer adhesive solution13may be prepared at a desired position. According to an embodiment, in each of the micro LED chips20, a connection pad22may be located on the polymer adhesive solution13in a connection pad-down state. For example, the micro LED chip20may have a size in the range of 10 μm to 100 μm, and may be generally constructed to have a size of tens of μm.

Referring toFIG.5B, according to an embodiment, the plurality of arrayed micro LED chip20may be attached on the coated polymer adhesive solution13. According to an embodiment, since the viscosity of the liquid polymer adhesive solution13is low, the micro LED chip20may gradually descend from an upper face of the polymer adhesive solution13by its own weight, heating, and pressure.

Referring toFIG.5C, according to an embodiment, the plurality of micro LED chips20descending by a first distance may have a space in which a peak140and the connection pad22are partially spaced apart from each other when energy is applied to the polymer adhesive solution13by heating (simple heat treatment at a temperature approximately less than or equal to 100 ° C.) and pressing (low pressure less than or equal to 1N/m2) and thus a distance between the connection pad and a peak of a ridge portion of a 3-dimensional conductive structure112reaches within the first distance, in an atmosphere state.

Referring toFIG.5D, through a continuous heating and pressing process of the polymer adhesive solution13, the peak140of the substrate11and the connection pad22may be physically in contact. That is, a conductive structure that can be electrically connected may be constructed. Since a chemical bond is achieved through a cold welding process of forming a metal-metal bond between the 3-dimensional conductive structure112and the connection pad22through an additional pressing process performed between the substrate11and the micro LED chip20which are physically connected, a more stable and reliable bonding and conductive structure can be constructed between the micro LED chip20and the substrate11.

After the cold welding process, the conductive structure of the micro LED chip20for which the chemical bond is achieved may be cured, and the connection pad22may be stably electrically connected to the circuit portion110through the 3-dimensional conductive structure112.

FIG.6AtoFIG.6Eare cross-sectional views sequentially illustrating a manufacturing process of a micro LED display according to various embodiments of the disclosure.

A method of manufacturing a micro LED display will be described as follows according to an embodiment with reference toFIG.6AtoFIG.6E.

Referring toFIG.6A, a substrate11having a circuit portion110constructed on one face may be prepared. According to an embodiment, a plating layer40may be constructed on the prepared substrate11. According to an embodiment, the plating layer40may be coated on the substrate11with a specific thickness. According to an embodiment, the plating layer40may be a 3-dimensional conductive structure. For example, the plating layer40may be a conductive layer containing a metal element such as gold. According to an embodiment, the plating layer40may have an upper face constructed in such a manner that a concave-convex shape is repeated, for example, by alternating a ridge portion and a valley portion. According to an embodiment, the circuit portion110may be a TFT circuit.

Referring toFIG.6B, according to an embodiment, after the plating layer40is constructed on the substrate11in a layer shape, the plating layer40may be present only on the circuit portion110through a masking and etching process. The plating layer40may not be present on a non-circuit portion of the substrate11. For example, the plating layer disposed only on the circuit portion110is denoted by a reference numeral400.

Referring toFIG.6C, according to an embodiment, a polymer adhesive solution14may be coated with a first thickness on the substrate11in which the plating layer400is constructed on the circuit portion110. For example, the first thickness of the polymer adhesive solution14may be in the range of 100 nm to 1000 m. According to an embodiment, in a coating method of the polymer adhesive solution14, large-area coating may use a spin coating method due to a low viscosity, and local coating may use a printing or jetting method. For example, the polymer adhesive solution14may have an adhesive strength of at least 1 Mn/m2.

A plurality of micro-sized electronic elements, such as a plurality of micro LED chips20, prepared on the substrate11coated with the polymer adhesive solution14may be prepared at a desired position. According to an embodiment, in each of the micro LED chips20, the connection pad22may be located on the polymer adhesive solution14in a pad-down state. For example, the micro LED chip20may have a size in the range of 10 μm to 100 μm, and may be generally constructed to have a size of tens of

Referring toFIG.6D, according to an embodiment, the plurality of arrayed micro LED chips20may be attached on the coated polymer adhesive solution14. According to an embodiment, since the viscosity of the liquid polymer adhesive solution14is low, the micro LED chip20may gradually descend from an upper face of the polymer adhesive solution14by its own weight, heating, and pressure.

According to an embodiment, the plurality of micro LED chips20descending by a first distance may have a space in which the upper face of the plating layer400and a connection pad22are partially spaced apart from each other when energy is applied to the polymer adhesive solution14by heating (simple heat treatment at a temperature approximately less than or equal to 100° C.) and pressing (low pressure less than or equal to 1N/m2) in an atmosphere state.

Referring toFIG.6E, through an additional heating and pressing process of the polymer adhesive solution14, a conductive structure capable of physically bonding, i.e. electrically connecting, the plating layer400and the connection pad22, may be constructed. Since a chemical bond is achieved between the plating layer40and the connection pad22through an additional pressing process performed between the substrate11and the micro LED chip20which are physically connected, a more stable and reliable bonding and conductive structure can be constructed between the micro LED chip20and the substrate11.

Then, after a cold welding process of forming a metal-metal bond through the pressing process of the plating layer40and the connection pad22of the micro LED chip20, the conductive structure of the micro LED chip20for which the chemical bond is achieved may be cured, and the connection pad22may be electrically connected to the circuit portion110through the plating layer400.

Referring toFIG.7, a micro LED display500which is componentized may be mounted on a main board to be manufactured as a large-screen display, and may be manufactured as a display of various sizes.

FIG.8is a plan view illustrating a large-sized display combined with a micro LED display610manufactured using a display manufacturing method according to various embodiments of the disclosure.

Referring toFIG.8, the plurality of micro LED displays610manufactured through the manufacturing process ofFIG.3AtoFIG.3Dmay be assembled to manufacture a micro LED display600(e.g., a large TV, a billboard, or the like) with more various widths.

Various embodiments of the disclosure disclosed in the present specification and the drawing are merely a specific example presented for clarity and are not intended to limit the scope of the embodiments of the present disclosure. Therefore, in addition to the embodiments disclosed herein, various changes in forms and details made without departing from the technical concept of the various embodiments of the disclosure will be construed as being included in the scope of the various embodiments of the present disclosure.

Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.