Etching glass and glass ceramic materials in hydroxide containing molten salt

Patent metadata

Field	Value
Publication number	US-2020377406-A1
Application number	US-202016886297-A
Country	US
Kind code	A1
Filing date	May 28, 2020
Priority date	May 31, 2019
Publication date	Dec 3, 2020
Grant date	—

Abstract

A method of etching a substrate comprises: contacting a substrate having a thickness with an etchant disposed in a vessel for a period of time until the thickness has reduced by at least 2 μm and at an average rate of 1 μm per minute to 6.7 μm per minute, the etchant having a temperature of 170° C. to 300° C. and comprising a molten mixture of two or more alkali hydroxides; and ceasing contacting the substrate with the etchant. The etchant in some instances comprises a molten mixture of NaOH and KOH. For example, the etchant in some instances includes a molten mixture of 24 wt. % to 72 wt. % NaOH, and 76 wt. % to 28 wt. % KOH. In some instances, the method alters the weight percentage of Na + , K + and Li + in the composition of the surface of the substrate by less than 1%.

First claim

What is claimed is:

1 . A method of etching a substrate comprising:
contacting a substrate having a thickness with an etchant disposed in a vessel for a period of time until the thickness has reduced by at least 2 μm and at an average rate of 1 μm per minute to 6.7 μm per minute, the etchant having a temperature of 170° C. to 300° C. and comprising a molten mixture of two or more alkali hydroxides; and ceasing contacting the substrate with the etchant.

2 . The method of claim 1 further comprising:
before contacting the substrate with the etchant, increasing a texture of a surface of the substrate.

3 . The method of claim 1 further comprising:
after ceasing contacting the substrate with the etchant, subjecting the substrate to an ion-exchange procedure.

4 . The method of claim 1 , wherein
the etchant further comprises one or more of an alkali nitrate and an alkali sulfate.

5 . The method of claim 1 , wherein
the etchant comprises a molten mixture of NaOH and KOH.

6 . The method of claim 1 , wherein
the substrate is an alkali aluminosilicate glass substrate or an alkali aluminosilicate glass-ceramic substrate.

7 . The method of claim 1 , wherein
the period of time is between 5 minutes and 2 hours.

8 . The method of claim 1 , wherein
the substrate has a composition; and the method alters a weight percentage of any one or more of Na + , K + , Li + in the composition from a surface to a depth of 1 μm into the thickness by less than 5%.

9 . The method of claim 1 , wherein
the substrate has a composition; and the method alters a weight percentage of any one or more of Ca ++ , Mg ++ in the composition from a surface to a depth of 1 μm into the thickness by less than 5%.

10 . The method of claim 1 , wherein the substrate is one of a plurality of substrates, each having a thickness, and, the method further comprises:
maintaining the etchant disposed in the vessel; and for each remaining substrate of the plurality of substrates sequentially:
(a) contacting the substrate with the etchant disposed in the vessel for a period of time until the thickness has reduced by at least 2 μm and at an average rate of 1 μm per minute to 6.7 μm per minute; and
(b) ceasing contacting the substrate with the etchant.

11 . The method of claim 10 , wherein
the plurality of substrates numbers at least 10 substrates; and each of the plurality of substrates was formed from the same batch composition.

12 . The method of claim 10 further comprising:
before contacting each remaining substrate of the plurality of substrates, increasing a texture of a surface of each remaining substrate of the plurality of substrates; and
tempering each remaining substrate of the plurality of substrates via an ion-exchange procedure.

13 . A system to reduce the thickness of a substrate comprising:
a vessel; an etchant disposed in the vessel, the etchant contacting a surface of the vessel, the etchant comprising a molten mixture of two or more alkali hydroxides, and the etchant having a temperature of 170° C. to 300° C.; and a substrate having a first position where the substrate does not contact the etchant, a second position where the substrate contacts the etchant, a third position where the substrate again does not contact the etchant, and a thickness that is at least 2 μm greater in the first position than in the third position and that decreases while in the second position at a rate of 1 μm per minute to 6.7 μm per minute.

14 . The system of claim 13 , wherein
the etchant comprises a molten mixture of NaOH and KOH.

15 . The system of claim 13 , wherein
the substrate is an alkali aluminosilicate glass substrate or an alkali aluminosilicate glass-ceramic substrate.

16 . The system of claim 13 , wherein
the thickness of the substrate in the third position is at least 20 μm less than the thickness of the substrate in the first position.

17 . The system of claim 13 , wherein
the substrate is in the second position for a period of time of 10 minutes to 30 minutes.

18 . The system of claim 13 , wherein
the etchant further comprises one or more of an alkali nitrate and an alkali sulfate.

19 . The system of claim 13 , wherein
the substrate further comprises a composition and a first surface that contacts the etchant in the second position of the substrate, and a weight percentage of any one or more of Na + , K + , Li + in the composition of the substrate from the first surface to a depth of 1 μm into the thickness when the substrate is in the third position is ±5% of the weight percentage of the any one or more of Na + , K + , Li + in the composition of the substrate from the first surface to a depth of 1 μm into the thickness when the substrate is in the first position.

20 . The system of claim 13 further comprising:
a plurality of substrates comprising the substrate, each of the plurality of substrates having the first position where the substrate does not contact the etchant, the second position where the substrate contacts the etchant, the third position where the substrate again does not contact the etchant, and the thickness that is greater in the first position than in the third position and that decreases while in the second position at a rate of 1 μm per minute to 6.7 μm per minute.

Assignees

• Corning Inc

Inventors

• Fahey Albert Joseph
• Jin Yuhui

Classifications

• B24C1/06

  for producing matt surfaces, e.g. on plastic materials, on glass · CPC title

• C03C3/085

  containing an oxide of a divalent metal · CPC title

• C03C3/083

  containing aluminium oxide or an iron compound · CPC title

• C03C3/087

  containing calcium oxide, e.g. common sheet or container glass · CPC title

• C03C3/095

  containing rare earths · CPC title