METHOD AND APPARATUS FOR PRODUCING FLEXIBLE OLED DEVICE
According to a flexible OLED device production method of the present disclosure, after an intermediate region (30i) and flexible substrate regions (30d) of a plastic film (30) of a multilayer stack (100) are divided from one another, the interface between the flexible substrate regions (30d) and a glass base (10) is irradiated with laser light. The multilayer stack (100) is separated into a first portion (110) and a second portion (120) while the multilayer stack (100) is in contact with a stage (212). The first portion (110) includes a plurality of OLED devices (1000) which are in contact with the stage (212). The OLED devices (1000) include a plurality of functional layer regions (20) and the flexible substrate regions (30d). The second portion (120) includes the glass base (10) and the intermediate region (30i).
The present disclosure relates to a method and apparatus for producing a flexible OLED device.
BACKGROUND ARTA typical example of the flexible display includes a film which is made of a synthetic resin such as polyimide (hereinafter, referred to as “plastic film”), and elements supported by the plastic film, such as TFTs (Thin Film Transistors) and OLEDs (Organic Light Emitting Diodes). The plastic film functions as a flexible substrate. The flexible display is encapsulated with a gas barrier film (encapsulation film) because an organic semiconductor layer which is a constituent of the OLED is likely to deteriorate due to water vapor.
Production of the above-described flexible display is carried out using a glass base on which a plastic film is formed over the upper surface. The glass base functions as a support (carrier) for keeping the shape of the plastic film flat during the production process. Elements such as TFTs and OLEDs, a gas barrier film, and the other constituents are formed on the plastic film, whereby the structure of a flexible OLED device is realized while it is supported by the glass base. Thereafter, the flexible OLED device is delaminated from the glass base and gains flexibility. The entirety of a portion in which elements such as TFTs and OLEDs are arrayed can be referred to as “functional layer region”.
According to the prior art, a sheet-like structure including a plurality of flexible OLED devices is delaminated from a glass base, and thereafter, optical parts and other constituents are mounted to this sheet-like structure. Thereafter, the sheet-like structure is divided into a plurality of flexible devices. This dividing is realized by, for example, laser beam irradiation.
Patent Document No. 1 discloses the method of irradiating the interface between each flexible OLED device and the glass base with laser light (lift-off light) in order to strip each flexible OLED device from the glass base (supporting substrate). According to the method disclosed in Patent Document No. 1, after irradiation with the lift-off light, respective flexible OLED devices are divided from one another, and each of the flexible OLED devices is delaminated from the glass base.
CITATION LIST Patent LiteraturePatent Document No. 1: Japanese Laid-Open Patent Publication No. 2014-48619
SUMMARY OF INVENTION Technical ProblemAccording to the conventional production method, the dividing by means of laser beam irradiation is carried out after expensive parts, for example, encapsulation film, polarizer, and/or heat radiation sheet, are mounted to a sheet-like structure including a plurality of flexible OLED devices. Therefore, unnecessary parts divided by laser beam irradiation, i.e., parts which are not to be constituents of a final OLED device, are quite useless. Also, there is a problem that, after being delaminated from the glass base, it is difficult to handle a plurality of flexible OLED devices which have no rigidity.
The present disclosure provides a method and apparatus for producing a flexible OLED device which are capable of solving the above-described problems.
Solution to ProblemA flexible OLED device production method of the present disclosure includes, in an exemplary embodiment, providing a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface; dividing the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film from one another; irradiating an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with laser light; and separating the multilayer stack into a first portion and a second portion by increasing a distance from a stage to the glass base while the second surface of the multilayer stack is kept in contact with the stage. The first portion of the multilayer stack includes a plurality of OLED devices which are in contact with the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film.
In one embodiment, separating the multilayer stack into the first portion and the second portion is carried out while the stage holds the second surface of the multilayer stack.
In one embodiment, irradiating the interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with the laser light is carried out while the stage holds the second surface of the multilayer stack.
In one embodiment, a surface of the stage includes a first region which is to face the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, and suction in the first region is greater than suction in the second region.
In one embodiment, the method further includes, before bringing the second surface of the multilayer stack into contact with the stage, placing a suction sheet on the stage, the suction sheet having a plurality of openings, wherein the stage includes a porous plate on which the suction sheet is to be placed, and the suction sheet includes a first region which is to be in contact with the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, an aperture ratio of the first region being higher than an aperture ratio of the second region.
In one embodiment, the method further includes, after separating the multilayer stack into the first portion and the second portion, sequentially or concurrently performing a process on the plurality of OLED devices which are in contact with the stage.
In one embodiment, the method further includes, after separating the multilayer stack into the first portion and the second portion, adhering another protection sheet to the plurality of OLED devices which are in contact with the stage.
In one embodiment, the method further includes detaching from the stage the plurality of OLED devices which are bound to the another protection sheet.
In one embodiment, the method further includes sequentially or concurrently performing a process on the plurality of OLED devices which are bound to the another protection sheet.
In one embodiment, the process includes attaching a dielectric and/or electrically-conductive film to each of the plurality of OLED devices.
In one embodiment, the process includes cleaning or etching each of the plurality of OLED devices.
In one embodiment, the process includes mounting an optical part and/or an electronic part to each of the plurality of OLED devices.
In one embodiment, the process includes cleaning or etching each of the plurality of OLED devices.
A flexible OLED device production apparatus of the present disclosure includes, in an exemplary embodiment, a stage for supporting a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface, the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film being divided from one another; a lift-off light irradiation unit for irradiating with laser light an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base in the multilayer stack supported by the stage; and an actuator for increasing a distance from the stage to the glass base while the stage holds the second surface of the multilayer stack by suction, thereby separating the multilayer stack into a first portion and a second portion. The first portion of the multilayer stack includes a plurality of OLED devices adhered by suction to the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film.
In one embodiment, the surface of the stage includes a first region which is to face the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, and suction in the first region is greater than suction in the second region.
In one embodiment, the stage includes a porous plate, and a suction sheet placed on the porous plate, the suction sheet having a plurality of openings, and the suction sheet includes a first region which is to be in contact with the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, an aperture ratio of the first region being higher than an aperture ratio of the second region.
A suction sheet of the present disclosure is, in an exemplary embodiment, a suction sheet for use in the above-described production apparatus, the suction sheet including: a first region which is to be in contact with the plurality of OLED devices; and a second region which is to face the intermediate region of the synthetic resin film, wherein an aperture ratio of the first region is higher than an aperture ratio of the second region.
Advantageous Effects of InventionAccording to an embodiment of the present invention, a novel method for producing a flexible OLED device which is capable of solving the above-described problems is provided.
An embodiment of a method and apparatus for producing a flexible OLED device of the present disclosure is described with reference to the drawings. In the following description, unnecessarily detailed description will be omitted. For example, detailed description of well-known matter and repetitive description of substantially identical elements will be omitted. This is for the purpose of avoiding the following description from being unnecessarily redundant and assisting those skilled in the art to easily understand the description. The present inventors provide the attached drawings and the following description for the purpose of assisting those skilled in the art to fully understand the present disclosure. Providing these drawings and description does not intend to limit the subject matter recited in the claims.
<Multilayer Stack>
See
The multilayer stack 100 includes a glass base (motherboard or carrier) 10, a plurality of functional layer regions 20 each including a TFT layer 20A and an OLED layer 20B, a synthetic resin film (hereinafter, simply referred to as “plastic film”) 30 provided between the glass base 10 and the plurality of functional layer regions 20 and bound to the glass base 10, and a protection sheet 50 covering the plurality of functional layer regions 20. The multilayer stack 100 further includes a gas barrier film 40 provided between the plurality of functional layer regions 20 and the protection sheet 50 so as to cover the entirety of the functional layer regions 20. The multilayer stack 100 may include another unshown layer, such as a buffer layer.
The first surface 100a of the multilayer stack 100 is defined by the glass base 10. The second surface 100b of the multilayer stack 100 is defined by the protection sheet 50. The glass base 10 and the protection sheet 50 are materials temporarily used in the production process but are not constituents of a final flexible OLED device.
The plastic film 30 shown in the drawings includes a plurality of flexible substrate regions 30d respectively supporting the plurality of functional layer regions 20, and an intermediate region 30i surrounding each of the flexible substrate regions 30d. The flexible substrate regions 30d and the intermediate region 30i are merely different portions of a single continuous plastic film 30 and do not need to be physically distinguished. In other words, parts of the plastic film 30 lying immediately under respective ones of the functional layer regions 20 are the flexible substrate regions 30d, and the other part of the plastic film 30 is the intermediate region 30i.
Each of the plurality of functional layer regions 20 is a constituent of a final flexible OLED device. In other words, the multilayer stack 100 has such a structure that a plurality of flexible OLED devices which are not yet divided from one another are supported by a single glass base 10. Each of the functional layer regions 20 has such a shape that, for example, the thickness (size in Z-axis direction) is several tens of micrometers, the length (size in X-axis direction) is about 12 cm, and the width (size in Y-axis direction) is about 7 cm. These sizes can be set to arbitrary values according to the required largeness of the display screen. The shape in the XY plane of each of the functional layer regions 20 is rectangular in the example illustrated in the drawings but is not limited to this example. The shape in the XY plane of each of the functional layer regions 20 may include a square, a polygon, or a shape which includes a curve in the contour.
As shown in
In an embodiment of the present disclosure, the configuration of the multilayer stack 100 is not limited to the example illustrated in the drawings. The number of functional layer regions 20 supported by a single glass base 10 is arbitrary.
The size or proportion of each component illustrated in respective drawings is determined from the viewpoint of understandability. The actual size or proportion is not necessarily reflected in the drawings.
The multilayer stack 100 which can be used in the production method of the present disclosure is not limited to the example illustrated in
<Dividing of OLED Devices>
According to the flexible OLED device production method of the present embodiment, after the step of providing the above-described multilayer stack 100, the step of dividing an intermediate region 30i and respective ones of a plurality of flexible substrate regions 30d of the plastic film 30 from one another is carried out.
When the cutting is realized by a laser beam, the wavelength of the laser beam may be in any of the infrared, visible and ultraviolet bands. From the viewpoint of reducing the effect of the cutting on the glass base 10, the laser beam desirably has a wavelength in the range of green to ultraviolet. For example, when a Nd:YAG laser device is used, the cutting can be carried out using a second harmonic wave (wavelength: 532 nm) or a third harmonic wave (wavelength: 343 nm or 355 nm). In such a case, the laser power is adjusted to 1 to 3 watts, and the scanning rate is set to about 500 mm per second, so that the multilayer structure supported by the glass base 10 can be cut (divided) into OLED devices and unnecessary portions without damaging the glass base 10.
According to the embodiment of the present disclosure, the timing of the above-described cutting is earlier than in the prior art. Since the cutting is carried out while the plastic film 30 is bound to the glass base 10, alignment for the cutting can be made with high precision and accuracy even if the gap between adjoining OLED devices 1000 is narrow. Thus, the gap between adjoining OLED devices 1000 can be shortened, and accordingly, useless portions which are unnecessary for a final product can be reduced. In the prior art, after the delaminating from the glass base 10, a polarizer, a heat radiation sheet, and/or an electromagnetic shield can be adhered to the plastic film 30 so as to cover the entirety of the surface (delaminated surface) of the plastic film 30. In such a case, the polarizer, the heat radiation sheet, and/or the electromagnetic shield are also divided by cutting into portions covering the OLED devices 1000 and the remaining unnecessary portions. The unnecessary portions are disposed of as waste. On the other hand, according to the production method of the present disclosure, production of such waste can be suppressed as will be described later.
<Lift-Off Light Irradiation>
After the intermediate region 30i and respective ones of the plurality of flexible substrate regions 30d of the plastic film 30 are divided from one another, the step of irradiating the interface between the flexible substrate regions 30d of the plastic film 30 and the glass base 10 with laser light is carried out using a delaminating apparatus.
In the example illustrated in
Then, as shown in
In the present embodiment, the delaminating apparatus includes a line beam source for emitting the lift-off light 216. The line beam source includes a laser device and an optical system for shaping laser light emitted from the laser device into a line beam.
Examples of the laser device that emits the lift-off light 216 include gas laser devices such as excimer laser, solid laser devices such as YAG laser, semiconductor laser devices, and other types of laser devices. A XeCl excimer laser device can generate laser light at the wavelength of 308 nm. When yttrium orthovanadate (YVO4) doped with neodymium (Nd) or YVO4 doped with ytterbium (Yb) is used as a lasing medium, the wavelength of laser light (fundamental wave) emitted from the lasing medium is about 1000 nm. Therefore, the fundamental wave can be converted by a wavelength converter to laser light at the wavelength of 340-360 nm (third harmonic wave) before it is used.
A sacrificial layer (a thin layer of a metal or amorphous silicon) may be provided at the interface between the plastic film 30 and the glass base 10. From the viewpoint of suppressing generation of ashes, using laser light at the wavelength of 308 nm from the excimer laser device, rather than laser light at the wavelength of 340-360 nm, is more effective. Providing the sacrificial layer is highly effective in suppressing generation of ashes.
The irradiation with the lift-off light 216 can be carried out with the power density (irradiance) of, for example, 250-300 mJ/cm2. The lift-off light 216 in the shape of a line beam has a size which can extend across the glass base 10, i.e., a line length which exceeds the length of one side of the glass base (long axis dimension, size in Y-axis direction of
The position of irradiation with the lift-off light 216 moves relative to the glass base 10 for scanning with the lift-off light 216. In the delaminating apparatus 220, the multilayer stack 100 may be movable while the light source 214 from which the lift-off light is to be emitted and an optical unit (not shown) are stationary, and vice versa. In the present embodiment, irradiation with the lift-off light 216 is carried out during a period where the stage 212 moves from the position shown in
<Lift-Off>
An actuator holds the glass base 10 and moves the entirety of the glass base 10 in the direction of arrow L, thereby carrying out delaminating (lift-off). The glass base 10 can be moved together with an unshown chuck stage while being adhered by suction to the chuck stage. The direction of movement of the glass base 10 does not need to be vertical, but may be diagonal, to the first surface 100a of the multilayer stack 100. The movement of the glass base 10 does not need to be linear but may be rotational. Alternatively, the stage 212 may be moved upward in the drawing while the glass base 10 is secured by an unshown holder or another stage.
In the example of
As described above, in the present embodiment, the step of separating the multilayer stack 100 into the first portion 110 and the second portion 120 is carried out while the stage 212 holds the second surface 100b of the multilayer stack 100 by suction. The essence of this separation step resides in that an unnecessary part of the multilayer stack 100 which is not a constituent of the OLED device 1000 separates together with the glass base 10 from the stage 212. In the present embodiment, the cutting step illustrated in
In the present embodiment, the stage 212 plays an important role in the above-described “separation”. Hereinafter, a configuration example of the stage 212 which can be suitably used in the present embodiment is described.
Configuration Example 1 of StageThe stage 212 shown in the drawings includes a plurality of first regions 300A which are to respectively face a plurality of OLED devices 1000 (not shown) and a second region 300B which is to face the intermediate region 30i of the plastic film 30. The suction in the first regions 300A is greater than the suction in the second region 300B.
The porous front plate 222 can be made of various porous materials. The porosity of the porous material is in the range of, for example, not less than 20% and not more than 60%. The average pore diameter is in the range of, for example, not less than 5 μm and not more than 600 μm. An example of the porous material is a sintered metallic or ceramic mass or a resin. The thickness of the porous material that forms the front plate 222 is in the range of, for example, not less than 1 mm and not more than 50 mm.
The suction sheet 300 has a plurality of through holes 300H as shown in
The suction sheet 300 can be made of various materials such as, for example, PET (polyethylene terephthalate), PVC (polyvinyl chloride), PP (polypropylene), fluoric resins (e.g., Polyflon), polyimide (PI), PC (polycarbonate), ABS resins. Alternatively, the suction sheet 300 may be made of woven fabric, nonwoven fabric, a porous film, or the like. The thickness of the suction sheet 300 can be, for example, about 0.05-3.0 mm.
The surface of the porous front plate 222 can achieve generally uniform sucking force. When the suction sheet 300 is placed, the suction differs between the first region 300A and the second region 300B. A region of the surface of the front plate 222 which is covered with unopened portions of the suction sheet 300 is incapable of sucking air and hence does not create suction. The suction sheet 300 can be used while it is adhered by suction to the porous front plate 222. The method of securing the suction sheet 300 to the surface of the front plate 222 is not limited to suction. The suction sheet 300 may be secured to the front plate 222 or the stage 212 via an adhesive layer or a jig.
Using the suction sheet 300 in combination with an existing chuck stage easily allows various designs of the multilayer stack 100. For example, when the shape, dimensions, number or arrangement pattern of the OLED devices 1000 is changed, the suction sheet is replaced by another suction sheet which is suitable to this change, whereby the in-plane distribution of the suction of the stage 212 can be easily changed. In other words, it is only necessary to replace the suction sheet 300 without changing the entirety of the stage 212.
In the present embodiment, the in-plane number density (hereinafter, simply referred to as “density”) of the through holes 300H in the first region 300A of the suction sheet 300 is higher than the density of the through holes 300H in the second region 300B. In other words, the aperture ratio of the first region 300A is higher than the aperture ratio of the second region 300B. Therefore, the suction (sucking force) in the second region 300B is smaller than the suction in the first region 300A. The density of the through holes in the second region 300B is about 0-50%, preferably about 0-30%, of the density of the through holes 300H in the first region 300A. In one embodiment, the density of the through holes 300H in the second region 300B may be 0/cm2.
The method of varying the suction between the first region 300A and the second region 300B is not limited to making difference in density of the through holes 300H in the suction sheet 300. By making difference in size and/or shape of the through holes 300H, difference can be made in aperture ratio, whereby the suction can be adjusted. Further, by making the thickness of the second region 300B of the suction sheet 300 smaller than the thickness of the first region 300A, a gap may be formed between the multilayer stack 100 and the second region 300B when the multilayer stack 100 is in contact with the first region 300A. Due to the presence of such a gap, the suction in the second region 300B can be decreased.
By using the stage 212 which has the above-described configuration, in the state shown in
Further, in irradiating with lift-off light, the irradiation intensity of the lift-off light may be decreased for at least part of the intermediate region 30i of the plastic film 30. If the irradiation intensity of the lift-off light is below a level required for delamination, that part of the intermediate region 30i of the plastic film 30 remains bound to the glass base 10. Thus, the intermediate region 30i of the plastic film 30 can easily be kept on the glass base 10.
If the distance from the stage 212 to the glass base 10 is increased while the stage 212 holds the second surface 100b of the multilayer stack 100 by suction, the unnecessary portions of the multilayer stack 100 can be separated together with the glass base 10 from the OLED devices 1000. The unnecessary portions of the multilayer stack 100 are not adhered by suction to the second region 300B of the stage 212 and remain bound to the glass base 10.
In the configuration example described with reference to
In this example, the density or aperture ratio of through holes 300H in the first region 212A is higher than the density or aperture ratio of through holes 300H in the second region 212B. Thus, the suction in the second region 212B is smaller than the suction in the first region 212A.
As described herein, the stage 212 may have a plurality of regions of different suctions.
<Steps after Delaminating>
Various processes can be sequentially or concurrently performed on the plurality of OLED devices 1000 which are in contact with the stage 212.
The “processes” to be performed on the OLED devices 1000 can include attaching a dielectric and/or electrically-conductive film to each of the plurality of OLED devices 1000, cleaning or etching each of the plurality of OLED devices 1000, and mounting an optical part and/or an electronic part to each of the plurality of OLED devices 1000. Specifically, a part such as, for example, a polarizer, encapsulation film, touchscreen, heat radiation sheet, electromagnetic shield, driver integrated circuit, or the like, can be mounted to the flexible substrate region 30d of each of the OLED devices 1000. The sheet-like part includes a functional film which can add an optical, electrical or magnetic function to the OLED devices 1000.
The plurality of OLED devices 1000 are supported by the stage 212 such that the OLED devices 1000 are adhered by suction to the stage 212. The various processes which are to be performed on each of the OLED devices 1000 can be efficiently carried out.
The surface 30s of the plastic film 30 delaminated from the glass base 10 is active. Therefore, the surface 30s may be covered with a protection film or subjected to a surface treatment for conversion to a hydrophobic surface before various parts are mounted to the surface 30s.
According to the prior art, the plastic film is delaminated from the glass base before the OLED devices 1000 are divided from one another. Therefore, when a subsequent process is carried out, a large number of OLED devices 1000 are bound to a single plastic film. Thus, it is difficult to carry out an efficient process on each of the OLED devices 1000. When the OLED devices 1000 are divided from one another after the sheet-like part is attached, a portion of the sheet-like part which is present in an intermediate region between adjoining two of the OLED devices 1000 is useless.
On the other hand, according to the embodiment of the present disclosure, a large number of OLED devices 1000 are still orderly arrayed on the stage 212 after being delaminated from the glass base 10. Therefore, various processes can be efficiently performed on the OLED devices 1000 sequentially or concurrently.
After the step of separating the multilayer stack 100 into the first portion 110 and the second portion 120, the step of adhering another protection sheet (second protection sheet) 70 to the plurality of OLED devices 1000 which are in contact with the stage 212 may be further performed as shown in
The second protection sheet 70 may be adhered to the plurality of OLED devices 1000 after various processes which have previously been described are performed on the plurality of OLED devices 1000 which are in contact with the stage 212.
When suction of the OLED devices 1000 by the stage 212 is stopped after the second protection sheet 70 is adhered, the plurality of OLED devices 1000 which are bound to the second protection sheet 70 can be detached from the stage 212. Thereafter, the second protection sheet 70 can function as a carrier for the plurality of OLED devices 1000. This is transfer of the OLED devices 1000 from the stage 212 to the second protection sheet 70. Various processes may be sequentially or concurrently performed on the plurality of OLED devices 1000 which are bound to the second protection sheet 70.
Multilayer Stack
Hereinafter, the configuration of the multilayer stack 100 before the dividing of
First, see
In the present embodiment, the plastic film 30 is a polyimide film having a thickness of, for example, not less than 5 μm and not more than 100 μm. The polyimide film can be formed from a polyamide acid, which is a precursor of polyimide, or a polyimide solution. The polyimide film may be formed by forming a polyamide acid film on the surface of the glass base 10 and then thermally imidizing the polyamide acid film. Alternatively, the polyimide film may be formed by forming, on the surface of the glass base 10, a film from a polyimide solution which is prepared by melting a polyimide or dissolving a polyimide in an organic solvent. The polyimide solution can be obtained by dissolving a known polyimide in an arbitrary organic solvent. The polyimide solution is applied to the surface 30s of the glass base 10 and then dried, whereby a polyimide film can be formed.
In the case of a bottom emission type flexible display, it is preferred that the polyimide film realizes high transmittance over the entire range of visible light. The transparency of the polyimide film can be represented by, for example, the total light transmittance in accordance with JIS K7105-1981. The total light transmittance can be set to not less than 80% or not less than 85%. On the other hand, in the case of a top emission type flexible display, it is not affected by the transmittance.
The plastic film 30 may be a film which is made of a synthetic resin other than polyimide. Note that, however, in the embodiment of the present disclosure, the process of forming a thin film transistor includes a heat treatment at, for example, not less than 350° C., and therefore, the plastic film 30 is made of a material which will not be deteriorated by this heat treatment.
The plastic film 30 may be a multilayer structure including a plurality of synthetic resin layers. In one form of the present embodiment, in delaminating a flexible display structure from the glass base 10, laser lift-off is carried out such that the plastic film 30 is irradiated with ultraviolet laser light transmitted through the glass base 10. A part of the plastic film 30 at the interface with the glass base 10 needs to absorb the ultraviolet laser light and decompose (disappear). Alternatively, for example, a sacrificial layer which is to absorb laser light of a certain wavelength band and produce a gas may be provided between the glass base 10 and the plastic film 30. In this case, the plastic film 30 can be easily delaminated from the glass base 10 by irradiating the sacrificial layer with the laser light. Providing the sacrificial layer also achieves the effect of suppressing generation of ashes.
<Polishing>
When there is an object (target) which is to be polished away, such as particles or protuberances, on the surface 30x of the plastic film 30, the target may be polished away using a polisher such that the surface becomes flat. Detection of a foreign object, such as particles, can be realized by, for example, processing of an image obtained by an image sensor. After the polishing process, a planarization process may be performed on the surface 30x of the plastic film 30. The planarization process includes the step of forming a film which improves the flatness (planarization film) on the surface 30x of the plastic film 30. The planarization film does not need to be made of a resin.
<Lower Gas Barrier Film>
Then, a gas barrier film may be formed on the plastic film 30. The gas barrier film can have various structures. Examples of the gas barrier film include a silicon oxide film and a silicon nitride film. Other examples of the gas barrier film can include a multilayer film including an organic material layer and an inorganic material layer. This gas barrier film may be referred to as “lower gas barrier film” so as to be distinguishable from a gas barrier film covering the functional layer regions 20, which will be described later. The gas barrier film covering the functional layer regions 20 can be referred to as “upper gas barrier film”.
<Functional Layer Region>
Hereinafter, the process of forming the functional layer regions 20, including the TFT layer 20A and the OLED layer 20B, and the upper gas barrier film 40 is described.
First, as shown in
More specifically, the functional layer regions 20 include a TFT layer 20A (lower layer) and an OLED layer 20B (upper layer). The TFT layer 20A and the OLED layer 20B are sequentially formed by a known method. The TFT layer 20A includes a circuit of a TFT array which realizes an active matrix. The OLED layer 20B includes an array of OLED elements, each of which can be driven independently. The thickness of the TFT layer 20A is, for example, 4 μm. The thickness of the OLED layer 20B is, for example, 1 μm.
The TFT layer 20A includes a selection TFT element Tr1, a driving TFT element Tr2, a data line DL, and a selection line SL. The OLED layer 20B includes an OLED element EL. Before formation of the OLED layer 20B, the upper surface of the TFT layer 20A is planarized by an interlayer insulating film that covers the TFT array and various wires. A structure which supports the OLED layer 20B and which realizes active matrix driving of the OLED layer 20B is referred to as “backplane”.
The circuit elements and part of the lines shown in
In the embodiment of the present disclosure, the TFT layer 20A and the OLED layer 20B can have various specific configurations. These configurations do not limit the present disclosure. The TFT element included in the TFT layer 20A may have a bottom gate type configuration or may have a top gate type configuration. Emission by the OLED element included in the OLED layer 20B may be of a bottom emission type or may be of a top emission type. The specific configuration of the OLED element is also arbitrary.
The material of a semiconductor layer which is a constituent of the TFT element includes, for example, crystalline silicon, amorphous silicon, and oxide semiconductor. In the embodiment of the present disclosure, part of the process of forming the TFT layer 20A includes a heat treatment step at 350° C. or higher for the purpose of improving the performance of the TFT element.
<Upper Gas Barrier Film>
After formation of the above-described functional layer, the entirety of the functional layer regions 20 is covered with a gas barrier film (upper gas barrier film) 40 as shown in
<Protection Sheet>
Next, refer to
After the thus-formed multilayer stack 100 is provided, the production method of the present disclosure can be carried out using the above-described production apparatus (delaminating apparatus 220).
INDUSTRIAL APPLICABILITYAn embodiment of the present invention provides a novel flexible OLED device production method. A flexible OLED device is broadly applicable to smartphones, tablet computers, on-board displays, and small-, medium- and large-sized television sets.
REFERENCE SIGNS LIST10 . . . glass base, 20 . . . functional layer region, 20A . . . TFT layer, 20B . . . OLED layer, 30 . . . plastic film, 40 . . . gas barrier film, 50 . . . protection sheet, 100 . . . multilayer stack, 212 . . . stage, 220 . . . delaminating apparatus, 1000 . . . OLED device
Claims
1. A method for producing a flexible OLED device, comprising:
- providing a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface;
- dividing the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film from one another;
- irradiating an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with laser light; and
- separating the multilayer stack into a first portion and a second portion by increasing a distance from a stage to the glass base while the second surface of the multilayer stack is kept in contact with the stage,
- wherein the first portion of the multilayer stack includes a plurality of OLED devices which are in contact with the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and
- the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film,
- the method further comprising, after separating the multilayer stack into the first portion and the second portion, sequentially or concurrently performing a process on the plurality of OLED devices which are in contact with the stage, wherein the process includes at least one of: attaching a dielectric and/or electrically-conductive film to each of the plurality of OLED devices; cleaning or etching each of the plurality of OLED devices; and mounting an optical part and/or an electronic part to each of the plurality of OLED devices.
2. The method of claim 1, wherein separating the multilayer stack into the first portion and the second portion is carried out while the stage holds the second surface of the multilayer stack.
3. The method of claim 2, wherein irradiating the interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with the laser light is carried out while the stage holds the second surface of the multilayer stack.
4. The method of claim 1 further comprising, after separating the multilayer stack into the first portion and the second portion, adhering another protection sheet to the plurality of OLED devices which are in contact with the stage.
5. A method for producing a flexible OLED device, comprising:
- providing a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface;
- dividing the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film from one another;
- irradiating an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base with laser light; and
- separating the multilayer stack into a first portion and a second portion by increasing a distance from a stage to the glass base while the second surface of the multilayer stack is kept in contact with the stage,
- wherein the first portion of the multilayer stack includes a plurality of OLED devices which are in contact with the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and
- the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film,
- the method further comprising, after separating the multilayer stack into the first portion and the second portion, adhering another protection sheet to the plurality of OLED devices which are in contact with the stage.
6. The method of claim 5 further comprising detaching from the stage the plurality of OLED devices which are bound to the another protection sheet.
7. The method of claim 6 further comprising sequentially or concurrently performing a process on the plurality of OLED devices which are bound to the another protection sheet,
- wherein the process includes at least one of: attaching a dielectric and/or electrically-conductive film to each of the plurality of OLED devices; cleaning or etching each of the plurality of OLED devices; and mounting an optical part and/or an electronic part to each of the plurality of OLED devices.
8. An apparatus for producing a flexible OLED device, comprising:
- a stage for supporting a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface, the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film being divided from one another;
- a lift-off light irradiation unit for irradiating with laser light an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base in the multilayer stack supported by the stage, the lift-off light irradiation unit configured to decrease an irradiation intensity of the laser light for at least part of the intermediate region such that the irradiation intensity of the laser light is below a level required for delamination; and
- an actuator for increasing a distance from the stage to the glass base while the stage holds the second surface of the multilayer stack by suction, thereby separating the multilayer stack into a first portion and a second portion,
- wherein the first portion of the multilayer stack includes a plurality of OLED devices adhered by suction to the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and
- the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film,
- the stage includes a porous plate, and a suction sheet placed on the porous plate, the suction sheet having a plurality of openings, and
- the suction sheet includes a first region which is to be in contact with the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, an aperture ratio of the first region being higher than an aperture ratio of the second region.
9. An apparatus for producing a flexible OLED device, comprising:
- a stage for supporting a multilayer stack which has a first surface and a second surface, the multilayer stack including a glass base which defines the first surface, a plurality of functional layer regions each including a TFT layer and an OLED layer, a synthetic resin film provided between the glass base and the plurality of functional layer regions and bound to the glass base, the synthetic resin film including a plurality of flexible substrate regions respectively supporting the plurality of functional layer regions and an intermediate region surrounding the plurality of flexible substrate regions, and a protection sheet which covers the plurality of functional layer regions and which defines the second surface, the intermediate region and respective ones of the plurality of flexible substrate regions of the synthetic resin film being divided from one another;
- a lift-off light irradiation unit for irradiating with laser light an interface between the plurality of flexible substrate regions of the synthetic resin film and the glass base in the multilayer stack supported by the stage, the lift-off light irradiation unit configured to decrease an irradiation intensity of the laser light for at least part of the intermediate region such that the irradiation intensity of the laser light is below a level required for delamination; and
- an actuator for increasing a distance from the stage to the glass base while the stage holds the second surface of the multilayer stack by suction, thereby separating the multilayer stack into a first portion and a second portion,
- wherein the first portion of the multilayer stack includes a plurality of OLED devices adhered by suction to the stage, and the plurality of OLED devices respectively include the plurality of functional layer regions and include the plurality of flexible substrate regions of the synthetic resin film, and
- the second portion of the multilayer stack includes the glass base and the intermediate region of the synthetic resin film, wherein
- a surface of the stage includes a first region which is to face the plurality of OLED devices and a second region which is to face the intermediate region of the synthetic resin film, and
- suction in the first region is greater than suction in the second region.
10. A suction sheet for use in the apparatus of claim 8, comprising:
- a first region which is to be in contact with the plurality of OLED devices; and
- a second region which is to face the intermediate region of the synthetic resin film,
- wherein an aperture ratio of the first region is higher than an aperture ratio of the second region.
Type: Application
Filed: Aug 5, 2021
Publication Date: Dec 2, 2021
Inventors: Kohichi TANAKA (Osaka), Katsuhiko KISHIMOTO (Osaka)
Application Number: 17/394,857