SECOND SURFACE LASER ABLATION

• US 20160199936A1
• Filed: 10/02/2015
• Published: 07/14/2016
• Est. Priority Date: 10/03/2014
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: LUTEN, Henry A., GEERLINGS, Kurtis L., BAREMAN, Donald L.
• Granted Patent: US 9,895,772 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23K 2103/08 Non-ferrous metals or alloys
• CPC Class Codes: B23K 2103/166 Multilayered materials
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/0661 disposed on the workpiece
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/362 Laser etching
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: B23K 26/57 the laser beam entering a face of the workpiece from which it is transmitted through the workpiece material to work on a different workpiece face, e.g. for effecting removal, fusion splicing, modifying or reforming
• CPC Class Codes: B29D 11/00596 Mirrors
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: C23C 30/00 Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process C23C26/00, C23C28/00 take precedence
• CPC Class Codes: G02F 1/153 Constructional details

Abstract

A method of removing material from an opposite side of workpiece includes directing a laser beam at a first side of the workpiece to remove the material from an opposite second side of the workpiece.

Claims

1. A method comprising:

providing a workpiece comprising a substrate, a coating layer disposed over a first surface of the substrate, and a mask disposed over a second surface of the substrate; and

removing a portion of the coating layer from the workpiece by directing a laser beam at the workpiece such that the laser beam passes through the substrate from the second surface to the first surface before the laser beam impinges on the coating layer;

wherein the first surface of the substrate and the second surface of the substrate are opposite surfaces of the substrate, and the mask selectively prevents removal of the coating layer from portions of the workpiece.

2. The method of claim 1, further comprising disposing the mask over the second surface of the substrate.

3. The method of claim 2, wherein disposing the mask comprises a photolithography process or a printing process.

4. The method of claim 2, wherein disposing the mask comprises placing a pre-formed mask over the second surface of the substrate.

5. The method of claim 1, wherein removing the portion of the coating layer produces portions of the workpiece from which the coating layer has been removed that have a characteristic dimension that is smaller than a laser spot produced by the laser beam.

6. The method of claim 1, wherein an edge of the coating layer adjacent the portion of the workpiece from which the coating layer has been removed has a characteristic length, L, that is a length of the portion of the edge of the coating layer in which a thickness of the coating layer tapers from a nominal coating layer thickness, t, to zero thickness, and L≦

100 μ

m.

7. The method of claim 6, wherein L≦

50 μ

m.

8. The method of claim 7, wherein L≦

200 nm.

9. The method of claim 1, wherein an edge of the coating layer adjacent the portion of the workpiece from which the coating layer has been removed has a uniform shape.

10. The method of claim 1, wherein an edge of the coating layer adjacent the portion of the workpiece from which the coating layer has been removed has a scalloped profile.

11. The method of claim 10, wherein a depth of the scallops is between 1% and 20% of a diameter of the laser beam.

12. The method of claim 10, wherein a depth of the scallops is less than 100 μ

m.

13. The method of claim 1, wherein the laser beam is produced by a laser with a pulse duration in a range of 0.5 to 500 picoseconds.

14. The method of claim 1, wherein the workpiece further comprises an electrically conductive layer disposed between the substrate and the coating layer, and the electrically conductive layer is not removed by the laser beam.

15. The method of claim 14, wherein the electrically conductive layer comprises a transparent conductive oxide.

16. The method of claim 15, wherein the transparent conductive oxide comprises indium tin oxide.

17. The method of claim 1, wherein the coating layer comprises a metallic material.

18. The method of claim 17, wherein the metallic material comprises chromium.

19. The method of claim 1, wherein the coating layer comprises multiple layers.

20. The method of claim 1, wherein an edge of the coating layer adjacent the portion of the workpiece from which the coating layer has been removed forms an average angle with the first substrate surface in a range of 30°

to 90°

.

21. The method of claim 1, wherein the portion of the workpiece from which the coating layer is removed exhibits a transmission haze of 0.05% or less.

22. The method of claim 1, wherein the portion of the workpiece from which the coating layer is removed exhibits a transmission haze of 0.25% or less.

23. A method comprising:

providing a workpiece comprising a substrate and a coating layer disposed over a first surface of the substrate; and

removing a portion of the coating layer from the workpiece by directing a laser beam at the workpiece such that the laser beam passes through the substrate before the laser beam impinges on the coating layer;

wherein the laser beam is produced by a laser with a pulse duration in a range of 0.5 to 500 femtoseconds.

24. The method of claim 23, wherein the workpiece further comprises a mask disposed over a second surface of the substrate, the first surface of the substrate and the second surface of the substrate are opposite surfaces of the substrate, and the mask selectively prevents removal of the coating layer from portions of the workpiece.

25. A product comprising:

a substrate;

a coating layer disposed over a first surface of the substrate; and

a portion of the first surface of the substrate that is substantially free of the coating layer;

wherein an edge of the coating layer adjacent the portion of the first surface of the substrate that is substantially free of the coating layer forms an average angle with the first substrate surface in a range of 30°

to 120°

, the edge of the coating layer adjacent the portion of the first surface of the substrate that is substantially free of the coating layer has a characteristic length, L, that is a length of the portion of the edge of the coating layer in which a thickness of the coating layer tapers from a nominal coating layer thickness, t, to zero thickness, and L≦

100 μ

m.

26. The product of claim 25, wherein L≦

50 μ

m.

27. The product of claim 26, wherein L≦

200 nm.

28. The product of claim 25, further comprising an electrically conductive layer disposed between the substrate and the coating layer and over the portion of the first surface of the substrate that is substantially free of the coating layer.

29. The product of claim 25, wherein the coating layer comprises a metallic material.

30. The product of claim 25, wherein the portion of the first surface of the substrate that is free of the coating layer exhibits a transmission haze of 0.05% or less.

31. The product of claim 25, wherein the portion of the first surface of the substrate that is free of the coating layer exhibits a transmission haze of 0.25% or less.

32. The product of claim 25, wherein the edge of the coating layer adjacent the portion of the first surface of the substrate that is substantially free of the coating layer has a scalloped profile.

33. The method of claim 32, wherein a depth of the scallops is less than 100 μ

m.

34. The method of claim 33, wherein a depth of the scallops is less than 50 μ

m.

35. The product of claim 25, further comprising:

a first electrode layer;

a second electrode layer; and

an electrochromic layer;

wherein the electrochromic layer is disposed between the first electrode layer and the second electrode layer, and the first electrode layer is disposed over the portion of the first surface of the substrate that is free of the coating layer.

36. A vehicle rearview mirror assembly comprising a product comprising:

a substrate;

a coating layer disposed over a first surface of the substrate; and

a portion of the first surface of the substrate that is substantially free of the coating layer;

wherein an edge of the coating layer adjacent the portion of the first surface of the substrate that is substantially free of the coating layer forms an average angle with the first substrate surface in a range of 30°

to 120°

, the edge of the coating layer adjacent the portion of the first surface of the substrate that is substantially free of the coating layer has a characteristic length, L, that is a length of the portion of the edge of the coating layer in which a thickness of the coating layer tapers from a nominal coating layer thickness, t, to zero thickness, and L≦

100 μ

m.