KR20080048272A - Manufacturing method of flexible display device - Google Patents

Abstract

A method for manufacturing a flexible display device is provided to include a stage for preparing first and second panels of which display devices are formed in each one side, thereby removing an adhesion stage. A method for manufacturing a flexible display device comprises the following steps of: forming first and second panels having display device patterns on each side of first and second substrates which non-flexibility is applied to and has a first thickness(S21); attaching the first panel and the second panel to face a side of the first substrate and a side of the second substrate(S23); etching the other side of each of the first and second substrates with the first thickness to have a second thickness which is thinner than the first thickness and which flexibility can be applied in(S25); and separating the first panel from the second panel(S27).

Description

Manufacturing method of flexible display device

1 is a flowchart illustrating a method of manufacturing a conventional flexible display device.

2 is a flowchart illustrating a method of manufacturing a flexible display device according to the present invention.

3 is a view for explaining an example of a display element formation process according to the present invention.

4A and 4B are views for explaining the bonding process according to the present invention.

5 is a view for explaining a substrate etching process according to the present invention.

6 is a view for explaining another substrate etching process according to the present invention.

7A and 7B are views for explaining a separation process according to the present invention.

8A and 8B are views for explaining various cutting methods included in the separating process according to the present invention.

<Explanation of symbols for the main parts of the drawings>

31, 31a, 31b: substrate d1: first thickness

d2: second thickness 40a, 40b: panel

49a, 49b, 43a, 43b: pattern of display element

45: sealant A1: display element formation region

B: cutting line

The present invention relates to a method of manufacturing a flexible display device. In particular, the present invention relates to a method of manufacturing a flexible display device which improves the reliability of the flexible display device and is not limited by the process temperature. Also, an object of the present invention is to provide a method of manufacturing a flexible display device which prevents damage to a display device during a substrate etching process.

The display device market has been rapidly shifting to flat panel displays instead of Cathode-Ray Tubes (CRTs). FPDs include liquid crystal displays (LCDs), plasma display panels (PDPs), organic electroluminescent displays (OLEDs), and the like. Such FPD is advantageous in light weight and thinness compared to CRT. FPD, on the other hand, uses glass substrates to withstand the high heat generated during the manufacturing process, thereby limiting light weight thinning and flexibility. Therefore, recently, a flexible display device manufactured to maintain display performance even if it is bent like a paper using a flexible material such as plastic instead of a glass substrate having no flexibility is emerging as a next generation display device.

1 is a flowchart illustrating a manufacturing method of a conventional flexible display device. Referring to FIG. 1, a method of manufacturing a conventional flexible display device is largely divided into an adhesion process S1, a display element forming process S3, and a peeling process S5.

Adhesion step S1 is a process of adhering a non-flexible support substrate to the back side of the flexible substrate using an adhesive to easily handle the flexible substrate, which is a substrate of the flexible display, during the process. . The support substrate adheres to the back side of the flexible substrate so that the flexible substrate is fixed without being easily bent or twisted during the process. As described above, the flexible substrate having a fixed shape through the adhesive process may be easily handled during the process, and a display device forming process, which is a subsequent process on the flexible substrate, may be performed more precisely and stably.

The display element forming step S3 is a step of forming various thin film patterns constituting the flexible display device. In general, the thin film patterns include a thin film transistor array.

Peeling process S5 is a process of peeling an adhesive and a support substrate from a flexible substrate after display element formation process S3. In order for the flexible display device to have flexibility, a process (S5) of peeling the support substrate adhered to the flexible substrate through the adhesion process (S1) is essential after the display element formation process (S3) is completed.

As described above, since the manufacturing process of the conventional flexible display device includes the peeling process S5, the adhesive should not be completely cured during the display element forming process S3 in order to facilitate peeling. In order to prevent the pressure-sensitive adhesive from curing completely, the maximum process temperature of the display element forming step S3 is limited to 150 ° C. or less. However, when a driving device of a display device such as a thin film transistor is manufactured at a low temperature of 150 ° C. or lower, the driving device's performance is deteriorated and its driving is not stable, which causes a decrease in reliability of the flexible display device.

In addition, the adhesion process S1 included in the manufacturing process of the conventional flexible display device should be performed so that bubbles are not formed between the flexible substrate and the adhesive. This is because when bubbles are formed between the flexible substrate and the pressure-sensitive adhesive, the bubbles deteriorate the reliability of the display element forming step (S3). Therefore, it is necessary to develop equipment that adheres to prevent bubbles from occurring between the flexible substrate and the adhesive during the adhesion process (S1). The development of such equipment causes a rise in the manufacturing cost of the flexible display.

In addition, the peeling process (S5) included in the manufacturing process of the conventional flexible display device is difficult to completely remove the adhesive from the flexible substrate, and the thin film patterns formed on the flexible substrate may be damaged by the peeling force. The thin film pattern damaged during the peeling process S5 may be another cause of lowering the reliability of the flexible display device.

An object of the present invention is to improve the reliability of the flexible display device, and to provide a method of manufacturing the flexible display device which is not limited by the process temperature. Another object of the present invention is to provide a method of manufacturing a flexible display device which prevents damage to a display device during a substrate etching process.

In order to achieve the above object, a display element forming step of forming a first panel and a second panel having a pattern of display elements on one surface of each of the first substrate and the second substrate having a first thickness imparting flexibility; Bonding the first panel and the second panel to face one surface of the first substrate and the second substrate; and forming the other surface of each of the first and second substrates having the first thickness. And etching the substrate to have a second thickness that is less than one thickness and imparts flexibility, and a separation step of separating the first panel and the second panel.

The forming of the display device may include forming a thin film transistor array on one surface of the first and second substrates.

The bonding may include applying a sealant to an edge of at least one of the first panel and the second panel so as to surround a region where the display element is formed.

The substrate etching step includes exposing the other surfaces of the first and second substrates to an etchant.

Exposing the other surfaces of the first and second substrates to the etchant includes dipping the other surfaces of the first and second substrates into the etchant.

Exposing the other surfaces of the first and second substrates to the etchant includes mounting the other surfaces of the first and second substrates sequentially on the conveyor belt to sequentially expose the etchant to the etchant.

The second thickness is 70% or less of the first thickness.

The first and second substrates include a metal substrate.

The metal substrate includes a stainless steel substrate.

The etchant contains a halogen element.

The etchant includes iron chloride.

The first thickness of the flexible substrate is 0.3 mm or more.

The separating may include cutting the first panel and the second panel corresponding to the cutting line between the region where the display element is formed and the sealant.

The cutting of the first panel and the second panel is performed using any one of a scribing wheel, a press, plasma, gas, laser, and hydraulic pressure.

Other objects and advantages of the present invention other than the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 2 to 6.

2 is a flowchart illustrating a manufacturing method of a flexible display device according to an exemplary embodiment of the present invention. Referring to FIG. 2, the method of manufacturing the flexible display device according to the present invention is largely divided into a display element forming process (S21), a bonding process (S23), a substrate etching process (S25), and a separation process (S27).

The display element forming step (S21) is a step of forming a display device by forming various patterns constituting the flexible display device on a non-flexible substrate. For example, when the display device is an electrophoretic display device (EPD), an electrophoretic display device as shown in FIG. 3 is formed through the display device formation process S21. Electrophoretic display devices are devices using electrophoresis (a phenomenon in which charged particles move toward an anode or a cathode in an electric field). The electrophoretic display device is formed by providing patterns of the display device on a substrate through a display device forming process (S21). The patterns of the electrophoretic display device are divided into a lower pattern including a thin film transistor array and an upper array unit including electrophoretic floating particles. The patterns of the electrophoretic display device are formed by patterning a lower pattern on a substrate and then attaching an upper array unit.

Referring to FIG. 3, the electrophoretic display device manufactured through the display device forming process S21 is described in detail. The electrophoretic display device is divided into a lower array unit 41 and an upper array unit 43.

The upper array portion 43 is generally in a flexible film state. The upper array portion 43 includes an upper electrode 84 formed on the base film 82, and capsules 85 disposed on the upper electrode 84 and including charge pigment particles. . The base film 82 is made of flexible plastic or flexible metal. The capsule 85 includes black dye particles 85a reacting with a positive voltage, white dye particles 85b reacting with a negative voltage, and a solvent 85c. In addition, the upper array portion 43 may further include an adhesive layer 86 under the capsule 85 so that the upper array portion 43 may be attached to the completed lower array portion 41.

The lower array part 41 may include a gate line (not shown) and a data line (not shown) formed to cross each other with a gate insulating layer 33 interposed therebetween on the substrate 31, and a thin film transistor formed at each intersection thereof. Transistor (hereinafter referred to as "TFT") 6 and a pixel electrode 17 formed in a cell region provided in a cross structure thereof. The substrate 31 in the display element forming step S21 is inflexible by having a first thickness that is rigid enough to withstand the display element forming step S21. A buffer layer may be further formed on the substrate 31 to improve the uniformity of the surface of the substrate 31 and to insulate the substrate 31. The TFT 6 includes a gate electrode 8 to which a gate voltage is supplied, a source electrode 10 connected to a data line, a drain electrode 12 connected to a pixel electrode 17, a gate electrode 8, An active layer 14 is provided that overlaps and forms a channel between the source electrode 10 and the drain electrode 12. The active layer 14 is formed to overlap the source electrode 10 and the drain electrode 12, and is exposed between the source electrode 10 and the drain electrode 12 to form a channel portion. An ohmic contact layer 16 for ohmic contact with the source electrode 10 and the drain electrode 12 is further formed on the active layer 14. Typically, the active layer 14 and the ohmic contact layer 16 are referred to as a semiconductor pattern 18. The pixel electrode 17 is in contact with the drain electrode 12 through the contact hole 17 exposing the drain electrode 12 through the protective film 35 protecting the TFT 6.

The electrophoretic display device includes a pixel electrode signal supplied to a data line in response to a gate voltage supplied to the gate electrode 8 of the lower array unit 41 via the channel of the TFT 6. Is charged and the reference voltage is supplied to the upper electrode 84 of the upper array unit 43, the white dye particles 85b and the black dye particles 85a in the capsule 85 by the electrophoretic phenomenon by the electric field. While dividing, it is possible to realize black, white or predetermined gray. The upper array portion 41 and the lower array portion 43 having such a configuration are bonded by the adhesive 86 included in the upper array portion 41.

As described above, the thickness of the substrate 31 on which the TFT array is formed has a first thickness to impart flexibility. The first thickness is preferably set to have a bending characteristic similar to that of the glass substrate of 0.7 mm. This is considered a liquid crystal display device (Liquid Crystal Display; hereinafter referred to as "LCD") that the development of the flat panel display device is activated. The liquid crystal display device includes a TFT array substrate, and in general, the TFT array of the liquid crystal display device is formed from a 0.7 mm glass substrate. Therefore, the process equipment for forming the TFT array of the liquid crystal display device is designed to be suitable for the bending characteristics of the glass substrate of 0.7mm. Accordingly, when the first thickness of the substrate 31 used in the display element forming process S21 according to the present invention is set to have a bending characteristic similar to that of the glass substrate of 0.7 mm, the display element forming process according to the present invention ( S21) has the advantage that the process equipment used to form the TFT array of the existing liquid crystal display device can be introduced as it is. In addition, since the substrate 31 formed with the first thickness is not deformed by the process heat, the TFT array can be formed without limiting the process temperature. As a result, since the TFT array can be formed at a temperature of 150 ° C. or higher, the performance deterioration of the driving device can be prevented.

The first thickness may have a different value depending on the type of the substrate 31. The substrate 31 uses a metal substrate mainly made of an Fe series and an alloy of another metal. More specifically, the measurement was performed using a stainless steel substrate (hereinafter referred to as "SUS substrate") in order to set the first thickness. As a result, the first thickness for the SUS substrate to have a bending characteristic similar to that of the glass substrate of 0.7 mm was measured to be 0.3 mm or more.

The display element forming step S21 as described above is performed by forming a pattern of the display element on one surface of each of the first substrate and the second substrate having the first thickness to impart flexibility. Accordingly, a first panel and a second panel having display elements formed on one surface of each of the first substrate and the second substrate through the display element forming process S21 according to the present invention are provided. Hereinafter, the first panel and the second panel will be described as an example of the electrophoretic display device shown in FIG.

Subsequently, the bonding process S23 is a process of bonding the first panel and the second panel to face one surface of the first substrate and the second substrate on which the display element is formed. Hereinafter, the bonding process S23 will be described in detail with reference to FIGS. 4A and 4B. As shown in FIG. 4A, the first panel 40a and the second panel 40b may be formed of the first substrate 31a and the first substrate d1 having a first thickness d1 that provides inflexibility by the display element forming process S21. After the lower patterns 49a and 49b including the TFT array and the pixel electrode described above with reference to FIG. 3 are patterned on one surface of each of the two substrates 31b, the upper array portions 43a and 43b are attached, respectively. . The first panel 40a and the second panel 40b are divided into a first region A1 where a display element is formed and a second region A2 except for the first region A1. The second area A2 surrounds the first area A1 as an edge of the first and second panels 40a and 40b. The sealant 45 is applied to at least one of the first panel 40a and the second panel 40b. The sealant 45 is preferably formed in the second area A2 so as not to invade the first area A1 to protect the display device. The first and second panels 40a and 40b are disposed such that one surface of the first and second substrates 31a and 31b face each other with the sealant 45 interposed therebetween, and then the sealant 45 is hardened and bonded.

After the bonding process S23, the first substrate 31a and the second substrate 31b have the other surfaces thereof, that is, the lower patterns 49a and 49b and the upper array unit (as shown in FIG. 5). The surface on which 43a and 43b is not formed is etched through the substrate etching process S25 to become the second thickness d2. The second thickness d2 is a thickness for providing flexibility to each of the first substrate 31a and the second substrate 31b. In general, when the second thickness d2 is etched to be 70% or less of the first thickness d1, the second thickness d2 may have flexibility. When the SUS substrate is applied, the second thickness d2 is preferably etched to be 0.2 mm or less.

The substrate etching process S25 may include the first panel 40a and the second panel 40b so that the other surfaces of the first substrate 31a and the second substrate 31b are immersed in the etchant 51 contained in the water tank 53. By dipping). The etchant 51 includes halogen elements such as chlorine (Cl), bromine (Br), and iodine (I). When the SUS substrate is applied, the etching solution 51 may include iron chloride to etch the SUS substrate.

The other surfaces of the first substrate 31a and the second substrate 31b that are dipped in this manner are etched in contact with the etching solution 51. The other surfaces of the first substrate 31a and the second substrate 31b are etched through the etchant to reach the second thickness, so that each of the first panel and the second panels 40a and 40b has flexibility. In addition, the sealant 45 in the substrate etching process S25 may prevent the etching solution 51 from penetrating into the first regions of the first and second panels 40a and 40b. Accordingly, the sealant 45 according to the present invention can prevent the display elements formed in the first regions of the first and second panels 40a and 40b from being damaged by the etchant 51. Thereafter, the remaining etchant 51 is removed by washing.

In addition to the dipping method, the substrate etching process S25 may be etched by the etching liquid 51 in which the other surfaces of the first substrate 31a and the second substrate 31b are sprayed through the nozzle 55 as shown in FIG. 6. Can be done. Referring to FIG. 6, a moving means such as a conveyor belt 57 may be exposed such that one surface of the other surface of the first substrate 31a or the second substrate 31b is exposed to the etching liquid 51 sprayed through the nozzle 55. Is mounted on. When the other surface of the first substrate 31a is first exposed, the first substrate 31a becomes the second thickness d2 first. Thereafter, the other surface of the second substrate 31b is turned upside down so as to be exposed to the etchant 51 and the second substrate 31b is etched to have a second thickness d2. Accordingly, each of the first panel and the second panel 40a and 40b has flexibility. As in the dipping method described above with reference to FIG. 5, in the substrate etching process S25, the sealant 45 may prevent the etching solution 51 from penetrating into the first regions of the first and second panels 40a and 40b. Can be. Accordingly, the sealant 45 according to the present invention can prevent the display elements formed in the first regions of the first and second panels 40a and 40b from being damaged by the etchant 51. Subsequently, the remaining etchant 51 is removed by washing.

Thereafter, the joined first and second panels 40a and 40b are separated into panels having respective display elements by removing the sealant 45 through a separation process S27. A separation process S27 will be described with reference to FIGS. 7A and 7B. As illustrated in FIG. 7A, after the substrate etching process S25, the first substrate 31a and the second substrate 31b are bonded to the sealant 45 with the second thickness d2. The sealant 45 is removed by cutting in various ways along the cutting line B of the first panel 40a and the second panel 40b, and the first panel 40a and the second panel 40b are illustrated in FIG. It is separated as shown in 6b. The cutting line B is preferably formed between the first region and the sealant 45. Each of the separated first panel 40a and the second panel 40b has a substrate 31a, 31b having a second thickness d2 and thus is in a flexible state.

8A and 8B are views for explaining various cutting methods included in the separation process according to the present invention. In the separation process according to the present invention, the first panel 40a and the second panel 40b are thinly etched to have a flexible state. Therefore, it is easy to cut along the cutting line B. FIG. Hereinafter, various cutting methods will be described. As shown in FIG. 8A, a portion of the first panel 40a and the second panel 40b may be removed by using the scribing wheel 81 to cross the cutting line B. As shown in FIG. Can be cut. The scribing wheel 81 is made of a material that is higher than the strength of the substrate of the first panel 40a and the second panel 40b. A representative example of the material of the scribing wheel 81 is diamond. As another cutting method, as shown in FIG. 8B, the first panel 40a and the first panel 40a are made through the cutter 85 using a press cutter 83 having a cutter 85 corresponding to the cutting line B. As shown in FIG. It can cut | disconnect by pressing 2 panels 40b. The cutter 85 cuts along the cutting line B by pressing the first panel 40a and the second panel 40b by converting the rotational motion into a linear motion by a crank included in the press cutter 83. can do. In addition, the cutter 85 can cut along the cutting line B by pressurizing the 1st panel 40a and the 2nd panel 40b by hydraulic pressure. In addition, the first panel 40a and the second panel 40b may be cut using plasma, gas, laser, and hydraulic pressure.

The above-described process has been described mainly for performing an etching process after the upper array unit is attached to the lower array unit, but the upper array unit may be attached to the lower array unit after the separation process of cutting the portion where the sealant is formed.

As described above, in the method of manufacturing the flexible display device according to the present invention, after forming the display element on one surface of the substrate having the first thickness to impart flexibility to withstand the display element formation process, the display device is formed to have the second thickness to impart flexibility. It is formed by etching the other surface of the substrate. In addition, the manufacturing method of the flexible display device according to the present invention prevents the display device from being damaged by the etching process by bonding the two panels on which the display device is formed using a sealant and then performing an etching process.

As described above, the method of manufacturing the flexible display device according to the present invention can eliminate the adhesion process by providing the first and second panels having the display elements formed on one surface of the non-flexible substrate.

In addition, the manufacturing method of the flexible display device according to the present invention can be manufactured even at a high process temperature by forming the display element on the inflexible substrate surface.

In addition, the method of manufacturing a flexible display device according to the present invention comprises the steps of bonding the first and second panels using a sealant to protect the surface on which the display element is formed, etching the other surface of the non-flexible substrate to a flexible state; Separating the first and second panel panels. Accordingly, since the method of manufacturing the flexible display device according to the present invention includes an etching process, the peeling process may be eliminated, and the sealant may be prevented from being damaged during the etching process.

As described above, the present invention can eliminate the adhesion process and the peeling process, which are factors that lower the reliability of the flexible display device, and can improve the reliability of the flexible display device without being limited by the process temperature.

In addition, the method of manufacturing a flexible display device according to the present invention forms a display element on a non-flexible substrate, and thus, it is unnecessary to develop equipment and to remodel existing equipment to improve the problem that the substrate is bent by process heat. Therefore, the manufacturing method of the flexible display device according to the present invention can apply the equipment for forming the thin film transistor of the existing liquid crystal display device as it is, it is possible to reduce the manufacturing cost and to easily secure the equipment for manufacturing the flexible display device. .

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (14)

A display element forming step of forming a first panel and a second panel having a pattern of display elements on one surface of each of the first and second substrates having a first thickness to impart flexibility; Bonding the first panel and the second panel to each other so that one surface of the first substrate and the second substrate face each other; Etching the other surface of each of the first and second substrates having the first thickness to have a second thickness that is thinner than the first thickness and imparts flexibility; And separating the first panel and the second panel. The method of claim 1, The display element forming step And forming a thin film transistor array on one surface of each of the first and second substrates. The method of claim 1, The bonding step is And applying a sealant to an edge of at least one of the first panel and the second panel so as to surround the region where the display element is formed. The method of claim 1, The substrate etching step And exposing the other surfaces of the first and second substrates to an etching solution. The method of claim 4, wherein Exposing the other surfaces of the first and second substrates to the etchant And dipping the other surfaces of the first and second substrates into the etching solution. The method of claim 4, wherein Exposing the other surfaces of the first and second substrates to the etchant And attaching the other surfaces of the first and second substrates sequentially to the conveyor belt to sequentially expose the etching liquid. The method of claim 1, And the second thickness is equal to or less than 70% of the first thickness. The method of claim 4, wherein The first and second substrates include a metal substrate. The method of claim 8, The metal substrate includes a stainless steel substrate. The method of claim 8, The etchant comprises a halogen element. The method of claim 10, The etchant comprises iron chloride. The method according to claim 1 or 7, The first thickness of the flexible substrate is 0.3mm or more manufacturing method of the flexible display device. The method of claim 3, wherein The separating step is And cutting the first panel and the second panel corresponding to the cutting line between the region where the display element is formed and the sealant. The method of claim 13, The cutting of the first panel and the second panel may be performed using any one of a scribing wheel, a press, a plasma, a gas, a laser, and a hydraulic pressure.

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