Flexible cover window and method of manufacturing same

1. A glass flexible cover window wherein a ratio of an intensity of replaced metal ions at a glass center to an intensity of replaced metal ions at a glass surface is 1:3 or greater,

a thickness of the glass is 30 microns, and

said glass flexible cover window comprises a tempered layer, wherein a depth and compressive stress of the tempered layer are adjusted by gradient tempering of the glass by performing a series of processes including primary tempering of the glass, partial slimming of the tempered layer resulting from the primary tempering, and secondary tempering of the glass resulting from the partial slimming, or by repeatedly performing the series of processes,

wherein a tempering time of the secondary tempering is set to be shorter than that of the primary tempering, or a tempering time of a subsequent tempering process is set to be shorter than that of a previous tempering process,

wherein the compressive stress achieved by the gradient tempering is higher than the compressive stress achieved by only primary tempering under the same tensile stress condition, and

the folding yield of the glass is about 100%, and the 2PB test value of the glass is an average of about 0.39R, an average of 20 Kgf in a puncture test of the glass with a 2 mm tip diameter; and an average of about 10 to about 20 cm in a pen drop test of the glass with a 6.2 g. pen with a tip having a diameter of 0.5 mm using an acrylic panel without optically clear adhesive.

2. A method of manufacturing the glass flexible cover window as claimed in claim 1 , the method comprising:

a first step of providing glass;

a second step of subjecting the glass to primary tempering to form a tempered layer on a surface of the glass;

a third step of subjecting the surface of the glass to slimming to reduce a depth of the tempered layer; and

a fourth step of subjecting the glass to secondary tempering to increase a compressive stress of the glass,

wherein a series of the second to fourth steps is repeatedly performed once or a plurality of times to achieve gradient tempering of the glass while increasing the compressive stress thereof.

3. The method of claim 2 , wherein a tempering time of the secondary tempering of the fourth step is set to be shorter than that of the primary tempering of the second step, or

a tempering time of a subsequent tempering process is set to be shorter than that of a previous tempering process.

4. The method of claim 2 , wherein the primary tempering of the second step and the secondary tempering of the fourth step are implemented by any one or a combination of at least two of an ion exchange process, an ion implantation process, and an ion assist process.

5. The method of claim 4 , wherein the primary tempering of the second step and the secondary tempering of the fourth step are implemented by applying any one of chemical dipping, chemical slurry, spray tempering, and paste tempering to each of the primary tempering and the secondary tempering, or by applying a combination of at least two of chemical dipping, chemical slurry, spray tempering, and paste tempering to each of the primary tempering and the secondary tempering.

6. The method of claim 4 , wherein after performing the primary tempering of the second step or after performing the secondary tempering of the fourth step, heat treatment or rapid cooling is performed.

7. The method of claim 4 , wherein the ion exchange process is performed by immersing the glass in a mixed metal salt or a single metal salt.

8. The method of claim 7 , wherein the mixed metal salt comprises at least one of LiNO 3 , NaNO 3 , KNO 3 , RbNO 3 , CsNO 3 , Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 , Rb 2 SO 4 , and Cs 2 SO 4 , and

the single metal salt is any one of LiNO 3 , NaNO 3 , KNO 3 , RbNO 3 , CsNO 3 , Li 2 SO 4 , Na 2 SO 4 , K 2 SO 4 , Rb 2 SO 4 , and Cs 2 SO 4 .

9. The method of claim 4 , wherein the flexible cover window is configured such that a ratio of an intensity of replacing metal ions at a glass center to an intensity of replacing metal ions at a glass surface is 1:3 or greater.

10. The method of claim 9 , wherein the replacing metal ions comprise K ions.

11. The method of claim 2 , wherein the slimming of the third step is implemented by any one or a combination of at least two of wet etching, polishing, laser forming, and masking, or wet etching, laser forming, or masking which use polishing as a post process.

12. The method of claim 2 , wherein the flexible cover window is configured such that the compressive stress achieved by the gradient tempering is relatively high even under the same tensile stress condition.