Photosensitive transfer resin for LED chip transfer, LED chip transfer method using the photosensitive transfer resin, and method for manufacturing a display device using the same

Abstract

The present invention relates to a photosensitive transfer resin, an LED chip transfer method, and a method for manufacturing a display device, which uses a technology of transferring LED chips formed on a wafer by etching and separating the separated chips to a carrier substrate, and a technology of selectively, sequentially, or at time intervals using a photosensitive transfer resin to transfer a portion of the chips transferred to the carrier substrate to other carrier substrates and a display panel. The photosensitive transfer resin for transferring LED chips in an embodiment of the present invention is a photosensitive transfer resin prepared by mixing a photosensitive resin, a mixed solvent, and a photoactive agent powder to obtain a photoactive agent solution. After the photosensitive transfer resin is exposed, it can be heated to expand without performing a development process, so as to be used for peeling or transferring the LED chip adhered to the photosensitive transfer resin.

Description

Technical Field

[0001] The present invention relates to a technology for transferring LED chips formed on a wafer by etching and separating the separated chips to a carrier substrate, a technology for transferring a part of the chips transferred to the carrier substrate to other carrier substrates and a display panel selectively, sequentially or at time intervals using a photosensitive transfer resin, a LED chip transfer method and a method for manufacturing a display device. Background Art

[0002] A light emitting diode (LED) is a type of light emitting element that emits light when an electric current is applied. A light emitting diode can emit light with high efficiency at a low voltage, and therefore has an excellent energy saving effect.

[0003] Recently, the grayscale problem of light emitting diodes has been greatly improved, and thus they are applied to various devices such as backlight units of liquid crystal display devices, electro-optical panels, displays, and home appliances.

[0004] The size of a micro light emitting diode (μ-LED) is very small, ranging from about 1 to 100 μm. A 40-inch display device requires about 25 million or more pixels.

[0005] Therefore, there is a problem that it takes at least one month to manufacture a 40-inch display device using a simple pick & place method.

[0006] Conventionally, multiple μ-LEDs are manufactured on a sapphire substrate and then transferred one by one to a glass or flexible substrate through a mechanical transfer method called pick & place.

[0007] Since the micro-LEDs are picked up one by one for transfer, it is called a 1:1 pick-and-place transfer method.

[0008] However, the micro LED chips made on the sapphire substrate are small in size and thin in thickness, so during the process of transferring the micro LED chips one by one, problems such as chip breakage, transfer failure, chip alignment failure or chip tilt may occur.

[0009] Furthermore, there is a problem that the transfer process takes too long.

[0010] [Prior art literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Korean Patent No. 10-0853410 Summary of the invention

[0013] Technical issues

[0014] The present invention aims to provide a method for selectively transferring photosensitive resins of multiple chips formed or arranged on a substrate by using UV and heat.

[0015] Furthermore, the present invention aims to provide a method capable of selectively transferring a plurality of chips formed on a base substrate using a predetermined photosensitive resin.

[0016] And, it is intended to provide a method capable of transferring a part of a plurality of chips transferred from a wafer to a first carrier substrate to a second carrier substrate by using a photosensitive resin.

[0017] And, it is intended to provide a method of manufacturing a display device which can transfer a chip selectively transferred to a second carrier substrate to a display panel by using a foam.

[0018] Furthermore, it is intended to provide a method for manufacturing display devices having various sizes and various pitches between pixels.

[0019] Furthermore, an object of the present invention is to provide a method capable of utilizing a wafer having as many RGB pixels as possible within a limited area regardless of the resolution of a display device.

[0020] Furthermore, it is intended to provide a method for rapidly manufacturing a display device.

[0021] The technical problems to be solved by the present invention are not limited to the technical problems described above, and ordinary technicians in the technical field to which the present invention belongs can clearly understand other problems not mentioned through the following description.

[0022] Technical Solution

[0023] The photosensitive transfer resin for transferring LED chips in the embodiment of the present invention is a photosensitive transfer resin prepared from a photoactive agent solution obtained by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder. After the photosensitive transfer resin is exposed, it can be heated to expand without undergoing a development process so as to be used for peeling or transferring the LED chip adhered to the photosensitive transfer resin.

[0024] The specific area of ​​the photosensitive transfer resin is exposed through a mask and UV irradiation to form a photodegradation layer, and when a predetermined heat is applied, the photodegradation layer expands to selectively peel off or transfer only the LED chip located in the photodegradation layer.

[0025] Furthermore, an LED chip transfer device using a photosensitive transfer resin according to an embodiment of the present invention comprises: a substrate; and a photosensitive transfer resin layer formed on the substrate and composed of a photosensitive resin that expands at a predetermined temperature; an LED chip is arranged on the photosensitive transfer resin layer, a specific area of ​​the photosensitive transfer resin layer is exposed through a mask and UV irradiation to form a photodegradation layer, and a predetermined heat is applied to expand the photodegradation layer, which can offset the adhesion of the LED chip located in the photodegradation layer to peel off or transfer the LED chip.

[0026] The photosensitive transfer resin is prepared by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder to obtain a photoactive agent solution, wherein the photoactive agent powder is more than 4 weight %. After the photosensitive transfer resin is exposed, it is not subjected to a development process but is heated to expand and form a transferable state.

[0027] Furthermore, the LED chip transfer method using photosensitive transfer resin in an embodiment of the present invention may include: a substrate preparation step of preparing a substrate; a photosensitive transfer resin layer forming step of forming a photosensitive transfer resin layer containing a photosensitive resin agent on the substrate; a photodegradation layer forming step of configuring a mask on the back side of the substrate and irradiating UV so that only specific areas are exposed; and a selective transfer step of selectively transferring the LED chip located on the photodegradation layer to the target substrate by applying a predetermined heat.

[0028] Furthermore, the manufacturing method of the display device according to the embodiment of the present invention may include: an LED chip forming step of forming a plurality of LED chips and a protective layer for passivating the plurality of LED chips on a wafer; an etching step of etching the protective layer according to each LED chip on the wafer; a primary transfer step of transferring the LED chip array arranged in rows, columns or matrices on the wafer by etching to a first carrier substrate formed with a photosensitive transfer resin layer containing a photosensitive resin agent; a wafer removal step of removing the wafer from the LED chip array; a secondary transfer step of transferring the LED chip array from the first carrier substrate to a second carrier substrate having an EMC adhesive layer obtained by mixing a second foam and an adhesive liquid; and a display panel transfer step of transferring the LED chip array from the second carrier substrate to a display panel.

[0029] The secondary transfer step may include: a step of forming a light-degradation layer by configuring a mask on the back side of the first carrier substrate and irradiating UV to expose specific areas of the photosensitive transfer resin layer; and a selective transfer step of applying a predetermined heat to selectively transfer the LED chip array located on the light-degradation layer to a second carrier substrate.

[0030] Technical Effects

[0031] According to the configuration of the present invention described above, there is an advantage that a plurality of chips formed or arranged on a base substrate can be selectively transferred using predetermined UV, heat, and pressure.

[0032] Furthermore, the present invention has the advantages of being able to separate the R chip, G chip and B chip formed on each wafer by etching, transferring the separated chips to a first carrier substrate, selectively transferring a part of the chips transferred to the first carrier substrate to a second carrier substrate, and sequentially transferring the chips transferred to the second carrier substrate to a display panel.

[0033] Furthermore, the present invention can selectively transfer a plurality of chips formed on a base substrate by targeted exposure of a predetermined photosensitive resin layer.

[0034] Furthermore, instead of controlling micro-level light-emitting elements one by one, a plurality of selected light-emitting elements can be transferred to the display panel at one time, thereby having the advantage of being able to significantly reduce the manufacturing cost and time of the display device.

[0035] Furthermore, when manufacturing a large-area display device, there is an advantage that the position can be changed and the transfer method can be repeatedly performed to rapidly manufacture the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A conceptual diagram for explaining an LED chip transfer method according to an embodiment of the present invention;

[0037] Figure 2 For Figure 1 The expansion ratio chart corresponding to the content of the photoactive agent in the photosensitive transfer resin shown;

[0038] Figure 3 A photograph showing the expansion state of a photosensitive transfer resin used for transferring an LED chip according to an embodiment of the present invention;

[0039] Figure 4 A method for transferring an LED chip according to an embodiment of the present invention is shown;

[0040] Figure 5 is a flowchart for explaining a method for manufacturing a display device according to an embodiment of the present invention;

[0041] Figure 6 A schematic diagram of forming chips on each wafer according to an embodiment of the present invention;

[0042] Figure 7 is an engineering diagram for growing each Epi on each wafer according to an embodiment of the present invention;

[0043] Figure 8A process diagram for etching each chip formed on each wafer as a chip unit according to an embodiment of the present invention;

[0044] Fig. 9 For the general Figure 8 An engineering drawing for transferring the etched chips from the wafer to the first carrier substrate;

[0045] Fig.10 Engineering drawings for wafer removal using LLO technology;

[0046] Figures 11 to 14 For the purpose of illustration Figure 5 The engineering diagram of the process (S160) of selectively transferring the chip array from the first carrier substrate to the second carrier substrate is shown;

[0047] Fig.15 Shown from Fig.14 The process of transferring the LED chip array from the second carrier substrate to the display panel (S170).

[0048] Description of Reference Numerals

[0049] 10R, 10G, 10B: Wafer

[0050] 100, 100R, 100G, 100B: LED chips

[0051] 210, 210R, 210G, 210B: first carrier substrate

[0052] 220, 220R, 220G, 220B: second carrier substrate

[0053] 300: Display board

[0054] 400: TFT array substrate DETAILED DESCRIPTION

[0055] When describing the implementation mode and recording that it is formed "on (above) or below (below)" of each component, the above (above) or below (below) covers the situation where two components are directly in contact with each other or one or more other components are arranged between the two components.

[0056] Furthermore, when expressed as "upper (above) or lower (below)", it includes not only an upper direction based on one component but also a lower direction.

[0057] The thickness or size of each layer in the drawings is exaggerated, omitted, or simply shown for the convenience and clarity of the description. In addition, the size of each component does not always reflect the actual size.

[0058] The chip, CSP, LED pixel CSP, and LED sub-pixel CSP used in the present invention can be defined as follows.

[0059] The term chip refers to a concept that includes LED chips, RGB chips, R chips, G chips, B chips, mini LED chips, and micro LED chips. For the convenience of explanation, the following description takes the chips as R chips, G chips, or B chips, but it should be noted that the chips are not limited to R chips, G chips, or B chips.

[0060] CSP (Chip Scale Package) is a package that has received great attention recently in the development of single chip packages. It refers to a single chip package with a semiconductor / package area ratio of more than 80%.

[0061] LED pixel CSP refers to a single package in which red LED, green LED and blue LED are packaged as one pixel unit and CSP is used to package one LED pixel.

[0062] LED sub-pixel CSP refers to a single package in which red LED, green LED, and blue LED are CSP packaged in units of one LED sub-pixel each.

[0063] The light emitting body formed on the wafer can be defined as an LED chip.

[0064] Figure 1 This is a conceptual diagram for explaining an LED chip transfer method according to an embodiment of the present invention.

[0065] The present invention utilizes the expansion of photosensitive resin.

[0066] That is, when a photosensitive resin (PR) is irradiated with UV, the phenolic varnish resin inside reacts with a photoactive agent and the like to generate acid. This acid is in a liquid state. When a wafer is placed on a heating plate (Hop Plate) and temperature is applied, only the area irradiated with UV expands. The liquid acid confined inside the PR expands only when its volume increases rapidly due to heat.

[0067] In order to increase the expansion force of the photosensitive resin so that the LED chip can be transferred, a photoactive agent is added to increase the acid content in the PR, thereby increasing the expansion force of the PR to prevent the cause of failure during transfer.

[0068] Figure 1 (A) simulates the expansion degree of the photosensitive transfer resin when irradiated with UV and heated when the content of the photoactive agent is low. Figure 1(B) simulates the expansion degree of the photosensitive transfer resin when irradiated with UV and heated when the content of the photoactive agent is high.

[0069] The photoactive agent has an inclusive meaning referring to any one of a photoacid generator (PAG), a PAC (PhotoActive compound), a photoinitiator, a photosensitive compound or a photoactive compound.

[0070] The photosensitive resin may be composed of novolac resin, solvent and photoactive agent, the solvent may be PGMEA or ethyl lactate, and the photosensitive transfer resin may be defined as a resin in which a photoactive agent solution is added to the photosensitive resin.

[0071] Figure 1 (A) is the case of a photosensitive transfer resin synthesized with a photoactive agent of 2 wt % or less, and (B) is the case of a photosensitive transfer resin synthesized with a photoactive agent of more than 6 wt %.

[0072] Photosensitive transfer resins 102 and 103 are applied on a substrate 101, and a mask 105 is arranged on the upper side thereof to irradiate UV.

[0073] The photosensitive transfer resins 102 and 103 expand in the region irradiated with UV, and the photosensitive transfer resins 102 and 103 do not expand in the region not irradiated with UV.

[0074] That is, the adhesion of the LED chips attached to the photosensitive transfer resins 102 and 103 can be reduced to zero according to the mask pattern and the presence or absence of UV irradiation, thereby enabling the LED chips to be selectively transferred to other substrates.

[0075] However, in case (A), the expansion force of the photosensitive transfer resin 102' is weak and therefore cannot fully fulfill the transfer function, whereas in case (B), the photosensitive transfer resin 103' makes the adhesion of the LED chip zero and has a sufficient expansion force to enable transfer to other substrates.

[0076] As a result, by mixing a considerable amount of photosensitizer solution into the photosensitive resin to form an exposure area irradiated with UV, heat is applied to the exposure area to expand the photosensitive transfer resin in the exposure area, so that the LED chip adhered to the exposure area can be peeled off, or the LED chip can be transferred to other LED chips. The photosensitive transfer resin can realize a new use (LED chip transfer use) by only undergoing an exposure process and not a development process.

[0077] Figure 2 For Figure 1 The expansion ratio chart corresponding to the content of photoactive agent in the photosensitive transfer resin is shown.

[0078] Figure 2 The graph shows the experimental results of verifying the content of photosensitizer in the photosensitive transfer resin and the expansion ratio of the photosensitive transfer resin.

[0079] Figure 2 The result values ​​of the graph shown are expressed in a table as follows, which shows relative values ​​when the same UV irradiation amount and the same temperature of heat are applied.

[0080]

Table 1

[0081]

[0082] It can be seen that the slope is very steep when the PAC content is 4 to 6 wt %, and it can be seen that the expansion force has a maximum efficiency value corresponding to the PAC content within this range.

[0083] The results show that the expansion ratio of the photosensitive transfer resin when the PAC content is 4 to 6 wt% has an expansion force of 1.8 to 5.6 times, which is a physical value that allows the LED chip to be detached, i.e. completely transferred, by reducing the adhesion of the LED chip to 0.

[0084] It can be seen that when the PAC content is 10 wt % or more, the expansion ratio converges to 6.0 times, so it can be seen that when the PAC content is 4 wt % or more, expansion for transferring the LED chip occurs.

[0085] Figure 3 The photographs show the expansion state of the photosensitive transfer resin used for transferring the LED chip according to the embodiment of the present invention.

[0086] A typical photosensitive material used for the positive photosensitive resin of the present invention may be naphtoquinonediazide-novolac resin.

[0087] When more than 4 wt % of a photoactive agent is mixed into a photosensitive resin and irradiated with light, photodecomposition occurs to form highly reactive ketene. The carboxylic acid formed by the reaction of ketene and water under the influence of the nitrogen gas generated at this time forms a positive image 104 according to a reaction mechanism in which the solubility in the imaging solution increases.

[0088] exist Figure 3 In the photographs, the upper left photograph is a photograph 103 of the photosensitive transfer resin before UV irradiation, and the upper right photograph is a photograph of a positive image 104 formed by UV irradiation.

[0089] The lower photograph is an enlarged photograph of a portion where a positive image, ie, an expanded area 103 ′, is formed by irradiating UV.

[0090] This expansion area can expand a specific position through a patterned mask, and the expansion ratio with maximum efficiency can be obtained by calculating the optimal ratio of the photoactive agent. The heat-induced expansion force of the photosensitive transfer resin used only in the embodiment of the present invention can break down the adhesion of the LED chip, thereby being able to perform the function of peeling or transferring the LED chip.

[0091] based on Figures 1 to 3 ,pass Figure 4 A detailed description of how the transfer process is actually carried out is provided. Figures 5 to 15 The process of transferring from wafer to display panel is described in more detail.

[0092] Figure 4 A LED chip transfer method according to an embodiment of the present invention is shown.

[0093] like Figure 4 As shown, the LED chip transfer device of the present invention may be constructed to include a substrate 101 , a photosensitive transfer resin layer 103 , and LED chips 100 , 100 ′.

[0094] The LED chips 100 and 100' may represent RGB LED chips, R LED chips, G LED chips, B LED chips, and CSP (Chip Scale Package). The LED chip pixel CSP may represent a package in which a red LED, a green LED, and a blue LED are used as a pixel unit and a CSP package is performed on an LED pixel. The LED sub-pixel CSP may represent a package in which a red LED, a green LED, and a blue LED are respectively CSP packaged in a sub-pixel unit and a LED sub-pixel unit.

[0095] The substrate 101 can be made of any material selected from glass, quartz, synthetic quartz and metal, and the material is not particularly limited.

[0096] The photosensitive transfer resin layer 103 may be a photosensitive resin material containing more than 4 wt % of a photoactive agent.

[0097] See also Figure 4 The process of peeling or transferring the LED chips 100 and 100 ′ at specific positions will be described.

[0098] See also Figure 4In (A), a photosensitive transfer resin layer 103 is formed on a substrate 101, and LED chips 100 and 100' are arranged or transferred (indicated by transfer from another substrate) on the photosensitive transfer resin layer 103.

[0099] See also Figure 4 (B), a mask 105 on which a pattern is to be formed is arranged on the back side of the substrate 101 and UV is irradiated through the mask 105 .

[0100] The photosensitive transfer resin area exposed by the mask 105 and irradiated with UV light is exposed to light as shown.

[0101] By using the mask 105 and irradiating UV, the photosensitive transfer resin has exposed areas and unexposed areas. This indicates that the photosensitive transfer resin is a positive resin, and the opposite is true when it is a negative resin.

[0102] See also Figure 4 (C), when heat is applied from the back side of the substrate 101 to a predetermined temperature, the exposed area in the photosensitive transfer resin layer 103 expands and its volume expands, and the expanded area 103' with volume expansion makes the adhesion of the LED chip 100 become 0.

[0103] In contrast, the unexposed region 103 does not expand, so the adhesion of the LED chip 100 remains unchanged.

[0104] See also Figure 4 (D), the LED chip 100 originally adhered to the corresponding position is peeled off, and when there is a target substrate on the opposite side, it can be transferred to the target substrate. The LED chip 100' originally adhered to other positions (not the position of the expansion area) is still configured on the substrate, and the LED chip can be selectively peeled off or transferred as needed.

[0105] The photosensitive transfer resin is only subjected to UV exposure and thermal expansion, but not development. This is different from the photosensitive resin used in semiconductor processes such as pattern formation.

[0106] See below Figures 5 to 15 A method of transferring the LED chip to a display panel using the LED chip transfer device is described in detail.

[0107] Figure 5 It is a flowchart for explaining the manufacturing method of the display device according to the embodiment of the present invention.

[0108] See also Figure 5The manufacturing method of the display device according to the embodiment of the present invention includes: a step of forming a plurality of chips on each wafer (S110), a step of etching the wafer according to each chip (S120), a step of attaching the chip array of each wafer separated by chip units to a first carrier substrate (S130), a step of removing the wafer by LLO (Laser Lift Off) process (S140), a step of preparing a second carrier substrate (S150), a step of selectively transferring the chip array from the first carrier substrate to the second carrier substrate (S160), a step of sequentially transferring the chip array selectively transferred to the second carrier substrate to a display panel (S170), and a step of removing the second carrier substrate (S180).

[0109] The specific embodiments are as follows.

[0110] Before step S130, a step of preparing a photoactive agent solution may be added.

[0111] Regarding the photoactive agent solution, a PAC solution was prepared by mixing 3 g of acetone and 1.6 g of photoactive agent (PAC).

[0112] A photosensitive transfer resin layer was prepared by mixing 10 g of a photosensitive resin and 2 g of a PAC solution.

[0113] In step S130 , a photosensitive transfer resin layer of the prepared photosensitive resin and PAC solution is coated on the first carrier substrate by spin coating.

[0114] The coated photosensitive transfer resin layer was soft-cured once at 105 degrees for 90 seconds, and then soft-cured twice at 105 degrees for 60 seconds.

[0115] In step S130 , heat is applied to the prepared photosensitive transfer resin layer at 105 degrees for 60 seconds, thereby transferring the LED chips on the wafer to the first carrier substrate.

[0116] In step S150 , an EMC (Expandable Micro-Capsule) adhesive layer mixed with a foam and an adhesive liquid is coated on the glass substrate to prepare a second carrier substrate or attach a thermal release film.

[0117] In step S160, a second carrier substrate is bonded to the opposite side of the first carrier substrate, and after being straightened using a mask straightener, 2,000 mJ of UV heat is irradiated, and the photosensitive transfer resin layer on the first carrier substrate is heated at 100 degrees for 20 seconds to expand it. At this time, the first carrier substrate is separated, and the LED chip is transferred to the second carrier substrate.

[0118] In steps S170 and S180 , the TFT array is prepared, and the second carrier substrate and the TFT array are combined after solder paste is applied.

[0119] The foam of the EMC adhesive layer of the second carrier substrate was foamed by heating at 200 degrees for 90 seconds to separate the second carrier substrate, and the LED chip was transferred to the display substrate (TFT array).

[0120] Figure 6 FIG. 1 is a schematic diagram of forming chips on each wafer according to an embodiment of the present invention.

[0121] like Figure 6 As shown, the embodiment of the present invention will be described by taking three wafers respectively formed with R chips, G chips and B chips as an example, but is not limited to this.

[0122] See also Figure 6 A plurality of light emitting elements 11R, 11G, and 11B emitting light in the same wavelength band are formed on each of the wafers 10R, 10G, and 10B.

[0123] The light emitting elements 11R, 11G, and 11B may be light emitting chips that emit red, green, and blue light.

[0124] The plurality of light emitting elements 11R, 11G, and 11B may be arranged at equal intervals along a plurality of rows and columns on each of the wafers 10R, 10G, and 10B.

[0125] The light emitting elements 11R, 11G, and 11B arranged at equal intervals are later transferred to the display panel in the row or column direction, so that the entire area of ​​the relatively expensive wafer can be effectively utilized to reduce the manufacturing cost of the light emitting elements.

[0126] In addition, after a plurality of chips are formed on each of the wafers 10R, 10G, and 10B, the wafers may be etched for each chip to separate the chips.

[0127] Preferably, the gap W between the chips formed on each of the wafers 10R, 10G, 10B is set to be the same as the gap between the chips formed on the display panel or to be a multiple of a predetermined value of a proportionality constant.

[0128] This enables easy transfer when the chips are selectively transferred in matrix units from the second carrier substrate to the display panel.

[0129] Figure 7 FIG. 1 is a diagram of an engineering process for growing each Epi on each wafer according to an embodiment of the present invention.

[0130] See also Figure 7 Epi layers 11R, 11G, and 11B emitting predetermined light are grown on one surface of each of the three wafers 10R, 10G, and 10B.

[0131] The wafers 10R, 10G, and 10B may be any substrate of sapphire Al2O3, silica gel, gallium arsenide (GaAs), gallium nitride (GaN), and zinc nitride (ZnN), but are not limited thereto, and any substrate that can be used as a wafer may be used.

[0132] The pads 14r, 14g, and 14b are formed on the grown Epi's 11R, 11G, and 11B, and a protective layer 13 is formed to passivate the Epi's 11R, 11G, and 11B and the pads 14r, 14g, and 14b.

[0133] The pads 14r, 14g, and 14b are not expanded and may have the size and shape of a general pad.

[0134] When forming the protection layer 13, it is preferred that the pads 14r, 14g, 14b are exposed outside the protection layer 13, which is beneficial to the subsequent expansion of the pad area.

[0135] Figure 7 Shown separately Figure 6 In the cross-sectional view of the AA cross section and the BB cross section, preferably, a pair of (+) and (-) electrodes are formed under the Epi layer of each chip. The electrodes can be formed up and down based on the AA cross section. Of course, they can also be formed left and right as needed.

[0136] The light emitters formed on the wafers 10R, 10G, and 10B are electrically separated in chip units, which are called LED chips in the present invention. They are then transferred from the wafers 10R, 10G, and 10B to the first carrier substrate after chip etching.

[0137] Figure 8 The figure is a process diagram for etching each chip formed on each wafer in units of one chip according to an embodiment of the present invention.

[0138] See also Figure 8 ,like Figure 7 Epi 11R, 11G, 11B and pads 14r, 14g, 14b are formed on wafers 10B, 10G, 10B, and the protective layer 13 is etched for each chip to form a plurality of physically separated chips 100R, 100G, 100B. In this specification, each chip and the protective layer 13 surrounding the chip are referred to as chips. Of course, each chip and the protective layer 13 surrounding the chip may also be referred to as a pixel CSP or a sub-pixel CSP.

[0139] The etching process for the chips 100R, 100G, and 100B may be performed by wet etching or dry etching, and the shape of the LED chip is defined by etching, while the wafers 10B, 10G, and 10B remain intact.

[0140] In the following figures, a chip 100R, 100G, 100B is shown as Figure 8 The chips 100R, 100G, and 100B are formed, but are not limited thereto. Figure 6 An array of chips 100R, 100G, 100B are etched in row and column directions.

[0141] Each of the chips 100R, 100G, and 100B may have a flip-chip structure that does not require wires.

[0142] The pads 14r, 14g, 14b may be used instead of wires for electrical connection, and the chips 100R, 100G, 100B may emit light of various colors based on external control signals received through the pads 14r, 14g, 14b, respectively.

[0143] Furthermore, in the present invention, the chips 100R, 100G, and 100B constitute sub-pixels of R, G, and B, respectively, so that a new concept of small-sized packaging in the form of CSP can be realized.

[0144] The R chip 100R, the G chip 100G, and the B chip 100B may constitute a light-emitting element or a light-emitting body.

[0145] A pre-processing can be performed to transfer the chip array by attaching each chip 100R, 100G, 100B to the first carrier substrate in multiple row and column directions, and selectively transferring from the first carrier substrate to the second carrier substrate. The chip array arranged on the second carrier substrate can be sequentially transferred to the following display panel.

[0146] The following instructions will be executed as Figure 8 The chip arrays etched into chips 100R, 100G, 100B on the wafers 10B, 10G, 10B are attached to a carrier substrate to remove the wafers, and then selectively transferred from the first carrier substrate to the second carrier substrate and then selectively transferred to the display panel.

[0147] The following figures will be Figure 6 The description is based on the row (horizontal) arrangement in the chip array arranged in a matrix on the wafer.

[0148] Fig. 9 For the general Figure 8 Engineering drawings of transferring the etched chips from the wafer to the first carrier substrate, Fig.10 Engineering drawing for wafer removal using LLO technology.

[0149] Fig. 9 and Fig.10This is a process of removing the wafers 10R, 10G, and 10B in order to transfer the etched chips to the first carrier substrate 210R.

[0150] The first carrier substrate 210R may be Figure 4 The transfer device has the same composition.

[0151] See also Fig. 9 , after separating the chips in the matrix direction by etching (such as Figure 8 As shown), the first carrier substrates 210R, 210G, 210B are attached to the LED chips 100R, 100G, 100B in the opposite direction of the wafers 10R, 10G, 10B.

[0152] That is, the first carrier substrates 210R, 210G, 210B are attached to the pads 14r, 14g, 14b sides of the chips 100R, 100G, 100B.

[0153] The first carrier substrate 210R, 210G, 210B includes substrates 211R, 211G, 211B and photosensitive transfer resin layers 213R, 213G, 213B.

[0154] The substrates 211R, 211G, and 211B may be made of any one of glass, quartz, synthetic quartz, and metal, without any particular limitation.

[0155] The photosensitive transfer resin layers 213R, 213G, and 213B are photosensitive resins containing 4 wt % or more of a photoactive agent.

[0156] See also Fig.10 , in such Fig. 9 In the state shown, when the wafers 10R, 10G, and 10B are removed by the LLO (Laser Lift Off) process, the LED chips 100R, 100G, and 100B are attached to the first carrier substrate 210R, 210G, and 210B. At this time, the directions of the chips 100R, 100G, and 100B are configured so that the light-emitting body is exposed in the opposite direction.

[0157] The first carrier substrates 210R, 210G, 210B may include a first carrier substrate 210R on which an R LED chip array is formed, a first carrier substrate 210G on which a G LED chip array is formed, and a first carrier substrate 210B on which a B LED chip array is formed.

[0158] Figures 11 to 14 For the purpose of illustration Figure 5An illustrative drawing showing a process of selectively transferring a chip array from a first carrier substrate to a second carrier substrate is shown.

[0159] Figures 11 to 14 Only Figures 7 to 10 The description is made based on any one of the RGB LED chips shown.

[0160] See also Fig.11 , a second carrier substrate 220 is disposed on the first carrier substrate 210 on which the LED chip array 100 is formed.

[0161] The EMC adhesive layer 223 contacts the second carrier substrate 220 on the LED chip 100 so as to be attached to each other.

[0162] The second carrier substrate 220 may be composed of an EMC adhesive layer 223 including a glass substrate 221 and a foam body 225 .

[0163] The foam body 225 may be a micro-unit encapsulated foaming substance having a foaming property at a predetermined temperature.

[0164] The EMC (Expandable Micro-Capsule) adhesive layer 223 may be a resin mixed with a foam 225 and an adhesive liquid.

[0165] See also Fig.12 The first carrier substrate 210 and the second carrier substrate 220 are as follows Fig.11 A mask 215 is disposed on the back surface of the glass substrate 211 of the first carrier substrate 210 in a state in which the glass substrate 211 is disposed opposite to the LED chip 100 therebetween.

[0166] The mask 215 may be a pre-patterned mask.

[0167] UV irradiation is performed with the mask 215 being arranged.

[0168] By patterning the mask 215 and irradiating with UV, only specific areas of the photosensitive transfer resin layer 213 can be exposed.

[0169] Among them, "Exposure" can adjust the exposure degree by controlling the UV exposure energy.

[0170] The exposed portion of the photosensitive resin adjusted by the UV irradiation amount can be called a photo-induced degradation layer.

[0171] When heat is applied to the light-degradable layer, the photosensitive transfer resin expands and the adhesion force of the LED chip becomes zero, thereby making it possible to selectively transfer only the LED chip at that position.

[0172] See also Fig.13 , heat is applied to the upper portion of the first carrier substrate 210 .

[0173] At this time, the heat may indicate an expandable temperature of the photosensitive transfer resin layer 213 .

[0174] When heat is applied to the first carrier substrate 210 so that the photosensitive transfer resin layer 213 reaches an expandable temperature, the photosensitive transfer resin layer 213 becomes a volume expanded photosensitive transfer resin layer 213'. At this time, the volume expandable position may be Fig.12 The area where the photodegradation layer exists is carried out.

[0175] The size of the volume-expanded photosensitive transfer resin layer 213' increases, and the pressure (expansion force) during the volume expansion pushes the LED chip 100 away, while the adhesion force of the LED chip 100 becomes 0. The LED chip 100 adhered to this position is peeled off (or transferred) and becomes capable of being transferred to the second carrier substrate 220.

[0176] See also Fig.14 , it can be seen that only specific LED chips 100 are selectively peeled off from the first carrier substrate 210 and transferred to the second carrier substrate 220 .

[0177] Fig.15 It is a cross-sectional view showing the process of transferring the LED chip array from the second carrier substrate 220 to the display panel 300.

[0178] See also Fig.15 (A), solder paste 33 is applied on the plurality of pads 31 of the display panel 300 .

[0179] A TFT array substrate 400 may be disposed below the display panel 300 .

[0180] The solder paste 33 may be applied to the pads 31 - SP1 ˜ 31 - SP4 in columns 1 to 4, or the solder paste 33 may be selectively applied to the pads at the positions where the LED chips 100 are to be transferred.

[0181] The solder paste 33 can be applied to the more than 300 solder pads 31 of the display panel 300 by various methods such as screen printing, dispensing, and spraying.

[0182] Afterwards, see Fig.15 (B), the LED chip array 100 attached to the second carrier substrate 220 is configured on the display panel 300, and the pads of the LED chip array 100 are arranged at the positions of the solder paste 33-SP1 to 33-SP4 coated on the pads 31 of the display panel 300.

[0183] Afterwards, see Fig.15 (C), heat is applied from the upper portion of the second carrier substrate 220 .

[0184] At this time, the heat refers to the temperature at which the foam 225 can foam.

[0185] The foam 225 expands in volume when heated, pushing away the EMC adhesive layer 223 including the impregnated adhesive liquid with a certain pressure, while causing the adhesion between the LED chip 100 and the second carrier substrate 220 to be lost, so that the LED chip 100 located on the EMC adhesive layer 223 line can be transferred to the display panel 300.

[0186] By repeatedly performing the above-mentioned process, the R, G, and B LED chips can be sequentially transferred on the display panel 300 at time intervals.

[0187] The features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, but are not limited to one embodiment. Moreover, a person skilled in the art of the embodiment can combine or modify the features, structures, effects, etc. illustrated in each embodiment in other embodiments for implementation. Therefore, the contents of these combinations and modifications should be interpreted as being included in the scope of the present invention.

[0188] Furthermore, although the above description is centered on the implementation mode, these are merely examples and do not limit the present invention. A person skilled in the art of the present invention may also perform various modifications and applications not illustrated above within the scope of the essential characteristics of the present implementation mode. For example, each component specifically appearing in the implementation mode may be implemented in a deformable manner. Furthermore, the differences in these modifications and applications should be interpreted as being included in the scope of the present invention as defined in the claims of the present invention.

Claims

1. A use of a photosensitive transfer resin for transferring LED chips, wherein the photosensitive transfer resin for transferring LED chips is a photosensitive transfer resin prepared from a photoactive agent solution obtained by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder. The purpose is to heat the photosensitive transfer resin to make it expand instead of developing it after exposure so as to peel off or transfer the LED chip adhered to the photosensitive transfer resin; The specific area of ​​the photosensitive transfer resin is exposed through a mask and UV irradiation to form a light-degradation layer. When a predetermined amount of heat is applied, the light-degradation layer expands to selectively peel off or transfer only the LED chip located in the light-degradation layer.

2. An LED chip transfer device using a photosensitive transfer resin, comprising: substrate; as well as A photosensitive transfer resin layer, formed on the substrate, and composed of a photosensitive resin that expands at a predetermined temperature; The photosensitive transfer resin layer is provided with an LED chip. The specific area of ​​the photosensitive transfer resin layer is exposed through a mask and irradiated with UV to form a light-degraded layer. applying a predetermined amount of heat to expand the light-degradation layer, thereby offsetting the adhesion of the LED chip located on the light-degradation layer to peel off or transfer only the LED chip located on the light-degradation layer, The photosensitive transfer resin is prepared by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder to obtain a photoactive agent solution.

3. The LED chip transfer device using photosensitive transfer resin according to claim 2, The photoactive agent powder is 4% by weight or more, After the photosensitive transfer resin is exposed, it is not subjected to a development process but is heated to expand the photosensitive transfer resin.

4. A method for transferring LED chips using a photosensitive transfer resin, comprising: a substrate preparation step of preparing a substrate; a photosensitive transfer resin layer forming step of forming a photosensitive transfer resin layer containing a photosensitive resin agent on the substrate; A light-degradation layer forming step of disposing a mask on the back side of the substrate and irradiating UV so that only a specific area of ​​the photosensitive transfer resin layer is exposed; as well as a selective transfer step of applying a predetermined amount of heat to expand the light-degradation layer, thereby offsetting the adhesion of the LED chip on the light-degradation layer to selectively transfer only the LED chip on the light-degradation layer to the target substrate, The photosensitive transfer resin is prepared by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder to obtain a photoactive agent solution.

5. The method for transferring LED chips using photosensitive transfer resin according to claim 4, The photoactive agent powder is 4% by weight or more, After the photosensitive transfer resin is exposed, it is not subjected to a development process but is heated to expand the photosensitive transfer resin.

6. A method for manufacturing a display device, comprising: An LED chip forming step of forming a plurality of LED chips on a wafer and a protective layer for passivating the plurality of LED chips; An etching step of etching the protective layer according to each LED chip on the wafer; A transfer step of transferring the LED chip array arranged in rows, columns or matrices on the wafer by etching to a first carrier substrate formed with a photosensitive transfer resin layer containing a photosensitive resin agent; A wafer removal step of removing the wafer from the LED chip array; A secondary transfer step of transferring the LED chip array from the first carrier substrate to a second carrier substrate having an expandable microcapsule adhesive layer obtained by mixing a second foam and an adhesive liquid; as well as a display panel transfer step of transferring the LED chip array from the second carrier substrate to a display panel, The secondary transfer step comprises: A step of forming a light-deteriorated layer by disposing a mask on the back side of the first carrier substrate and irradiating UV light to expose a specific area of ​​the photosensitive transfer resin layer; as well as a selective transfer step of applying a predetermined amount of heat to expand the light-degradation layer, thereby offsetting the adhesion of the LED chip array on the light-degradation layer to selectively transfer only the LED chip array on the light-degradation layer to a second carrier substrate, The photosensitive transfer resin is prepared by mixing a photosensitive resin, a mixed solvent and a photoactive agent powder to obtain a photoactive agent solution.

7. The method for manufacturing a display device according to claim 6, wherein the display panel transfer step comprises: The step of applying solder paste on a plurality of pads of the display panel; A step of bringing the pads of the LED chip array transferred to the second carrier substrate into contact with the applied solder paste for soldering; as well as A step of applying a predetermined amount of heat to the second carrier substrate to transfer the selectively transferred LED chip array to the display panel through thermal expansion of the second foam body.

8. The method for manufacturing a display device according to claim 6, The photoactive agent powder is 4% by weight or more, After the photosensitive transfer resin is exposed, it is not subjected to a development process but is heated to expand the photosensitive transfer resin.

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