Method of manufacturing flexible display device

1. A method of manufacturing a flexible display device, the method comprising:

preparing a first flexible substrate on which a display unit is formed;

forming an encapsulation unit comprising a base substrate, a second flexible substrate formed on the base substrate, and a barrier layer formed on the second flexible substrate;

combining the encapsulation unit with the display unit; and

separating the base substrate from the second flexible substrate by using a difference between a coefficient of thermal expansion of the base substrate and a coefficient of thermal expansion of the second flexible substrate, by applying a heated solution between the base substrate and the second flexible substrate.

2. The method of claim 1 , wherein, in the forming of the encapsulation unit, the base substrate is a film substrate having a first coefficient of thermal expansion, and the second flexible substrate is a flexible film substrate having a second coefficient of thermal expansion higher than the first coefficient of thermal expansion, the second flexible substrate being thinner than the base substrate.

3. The method of claim 2 , wherein the base substrate comprises glass.

4. The method of claim 2 , wherein the second flexible substrate comprises any one of polycarbonate (PC), polyethersulphone (PES), polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), polyimide (PI), polyarylate (PAR), and fiber glass reinforced plastic (FRP).

5. The method of claim 2 , wherein the second flexible substrate is formed by coating a polymer material for forming the second flexible substrate on the base substrate.

6. The method of claim 1 , wherein, in the separating of the base substrate from the second flexible substrate, the solution comprises water having a temperature higher than room temperature.

7. The method of claim 1 , wherein the base substrate is separated from the second flexible substrate by dipping the combined first flexible substrate and encapsulation unit in the heated solution.

8. The method of claim 1 , wherein the base substrate is separated from the second flexible substrate by spraying a portion between the base substrate and the second flexible substrate with the heated solution.

9. A method of manufacturing a flexible display device, the method comprising:

forming a first barrier layer on a first flexible substrate;

forming a thin film transistor on the first barrier layer;

forming a display unit electrically connected to the thin film transistor, on the thin film transistor;

forming an encapsulation unit comprising a base substrate, a second flexible substrate formed on the base substrate, and a second barrier layer formed on the second flexible substrate;

combining the encapsulation unit with the display unit; and

separating the base substrate from the second flexible substrate by using a difference between a coefficient of thermal expansion of the base substrate and a coefficient of thermal expansion of the second flexible substrate, by applying a heated solution between the base substrate and the second flexible substrate.

10. The method of claim 9 , wherein, in the forming of the encapsulation unit, the encapsulation layer is manufactured separately from the display unit, and combined to the display unit.

11. The method of claim 9 , wherein the base substrate is a film substrate having a first coefficient of thermal expansion, and the second flexible substrate is a flexible film substrate having a second coefficient of thermal expansion higher than the first coefficient of thermal expansion, the second flexible substrate being thinner than the base substrate.

12. The method of claim 11 , wherein the base substrate comprises glass.

13. The method of claim 11 , wherein the second flexible substrate comprises any one of polycarbonate (PC), polyethersulphone (PES), polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), polyimide (PI), polyarylate (PAR), and fiber glass reinforced plastic (FRP).

14. The method of claim 9 , wherein the second flexible substrate is formed by coating a polymer material for forming the second flexible substrate on the base substrate.

15. The method of claim 9 , wherein, in the separating of the base substrate from the second flexible substrate, the solution comprises water having a temperature higher than room temperature.

16. The method of claim 9 , wherein the base substrate is separated from the second flexible substrate by dipping the combined first flexible substrate and encapsulation unit in the heated solution or spraying a portion between the base substrate and the second flexible substrate with the heated solution.

17. The method of claim 9 , further comprising forming an additional base substrate for supporting the first flexible substrate, below the first flexible substrate.

18. The method of claim 17 , wherein the additional base substrate is formed of the same material as the base substrate of the encapsulation unit, and the first flexible substrate is formed of the same material as the second flexible substrate.

19. The method of claim 17 , wherein the additional base substrate is separated from the first flexible substrate by dipping the additional base substrate in the heated solution or spraying a portion between the additional base substrate and the first flexible substrate with the heated solution.

20. The method of claim 17 , wherein the first and second barrier layers are an organic layer or an inorganic layer, or have a multi-layer structure, wherein an organic layer and an inorganic layer are alternately stacked.