Laser-processable glass substrate and laser processing method

• US 6,262,389 B1
• Filed: 09/22/1998
• Issued: 07/17/2001
• Est. Priority Date: 03/25/1996
• Status: Expired due to Fees

• Current Assignee: Nippon Sheet Glass Company Limited
• Original Assignee: Nippon Sheet Glass Company Limited
• Inventors: Koyama, Tadashi, Tsunetomo, Keiji
• Primary Examiner(s): Robinson, Ellis
• Assistant Examiner(s): Lee, Laura L.
• Application Number:
  US09/155,126
• Time in Patent Office: 1,029 Days
• Field of Search: 428/410, 428/34.4, 428/673, 428/131, 219/121.85, 204/121.71, 204/192.2, 651/12, 65/61, 65/301, 65/31, 65/301.3
• US Class Current: 219/121.71
• CPC Class Codes: C03C 21/005 to introduce in the glass such metals or metallic ions as Ag, Cu
• CPC Class Codes: C03C 23/0025 by a laser beam
• CPC Class Codes: C03C 23/007 by thermal treatment
• CPC Class Codes: C03C 4/06 for phototropic or photochromic glass
• CPC Class Codes: Y10T 428/12896 Ag-base component
• CPC Class Codes: Y10T 428/131 Glass, ceramic, or sintered, fused, fired, or calcined metal oxide or metal carbide containing [e.g., porcelain, brick, cement, etc.]
• CPC Class Codes: Y10T 428/24273 including aperture
• CPC Class Codes: Y10T 428/315 Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

A sheet of silicate glass having a thickness of 2 mm and composed mainly of SiO₂, and containing Al₂O₃, B₂O₃, Na₂O, F, etc., is immersed in a molten salt comprising a mixture of 50 mol % of silver nitrate and 50 mol % of sodium nitrate. Na ions in the surface of the glass are eluted, diffusing Ag ions in the molten salt into the glass. When a laser beam is applied to the glass substrate thus formed, the glass substrate is evaporated or ablated progressively from its surface. The glass substrate is processed to a smooth finish without causing cracking or breakage.

Claims

1. Method of producing a glass article having at least one hole (h) or a recess, respectively, at a predetermined location in the surface thereof,

characterized by the steps of

providing a glass substrate (G) containing silver in the form of Ag atoms, an Ag colloid, or Ag ions, and having such a concentration gradient that the concentration of silver is greatest at said surface and progressively decreases from the surface towards the interior, and

forming said at least one hole (h) or recess by irradiating said glass substrate (G) at said predetermined location with a laser beam, thereby to remove portions of said glass substrate (G) by way of melting, evaporation or ablation due to absorption of energy of said laser beam.

2. Method of producing a glass article according to claim 1, characterized by the step of applying ultraviolet radiation to the glass substrate to reduce Ag ions in the glass substrate into a colloid prior to applying said laser beam to said predetermined location.

3. Method of producing a glass article according to claim 1, characterized in that the silver content of said glass substrate is locally restricted to a predetermined depth from the surface towards the interior of said glass substrate.

4. Method of producing a glass article according to claim 1, characterized in that said glass substrate contains silver throughout its entirety and having such a concentration gradient that the concentration of silver is greatest at said surface and progressively decreases from said surface to an opposite surface.

5. Method of producing a glass article according to claim 1, characterized in that said glass substrate contains silver throughout its entirety and having such a concentration gradient that the concentration of silver is smallest at an intermediate region in a direction transversely across the glass substrate and progressively increases towards opposite surfaces thereof.

6. Method of producing a glass article according to claim 1, characterized in that said glass substrate (G) is of planar shape.

7. Method according to claim 1 characterized in that said glass substrate comprises silicate glass composed primarily of SiO₂.

8. Method of producing a glass article according to claim 1, characterized in that said glass substrate contains F (fluorine).

9. Method of producing a glass article according to claim 1, characterized in that the silver is introduced in the glass substrate as Ag ions to replace other one-valance positive ions by an ion exchange.

10. Method of producing a glass article according to claim 1 wherein the greatest concentration of silver is at least 0.1 mol %.

11. Method of producing a glass article according to claim 1, characterized in that said glass substrate is annealed to lessen the concentration gradient of silver.