Second surface laser ablation

• US 10,610,975 B2
• Filed: 02/15/2018
• Issued: 04/07/2020
• 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.
• Primary Examiner(s): Thomas, Brandi N
• Application Number:
  US15/897,419
• Publication Number:
  US 20180169793A1
• Time in Patent Office: 782 Days
• Field of Search: 359237, 359265-267, 359273-275, 359290-292, 359295, 359298, 359315, 359321, 359322
• 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 having a first surface and an opposing second surface;

disposing a coating layer over the 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 from the opposing second surface to the first surface before the laser beam impinges on the coating layer;

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.

2. The method of claim 1, wherein disposing the mask comprises a photolithography process or a printing process.

3. The method of claim 1, wherein disposing the mask comprises placing a pre-formed mask over the second surface of the substrate.

4. 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.

8. 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.

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 scalloped profile.

10. The method of claim 9, wherein a depth of the scallops is between 1% and 20% of a diameter of the laser beam.

11. The method of claim 9, wherein a depth of the scallops is less than 100 μ

m.

12. 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.

15. The method of claim 1, wherein the coating layer comprises a chromium-containing metallic material.

16. 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°

.

17. 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.

18. 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.

5. A method comprising:

providing a workpiece comprising a substrate;

disposing a coating layer over a first surface of the substrate;

disposing a mask 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; and

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.

6. The method of claim 5, wherein L≤

50 μ

m.

7. The method of claim 6, wherein L≤

200 nm.

13. A method for comprising:

providing a workpiece comprising a substrate having a first surface and an opposing second surface;

disposing an electrically conductive layer over the first surface;

disposing a coating layer over the electrically conductive layer such that the electrically conductive layer is disposed between the substrate and the coating layer;

disposing a mask over the opposing second surface of the substrate;

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 opposing second surface to the first surface and through the electrically conductive layer before the laser beam impinges on the coating layer;

wherein the mask selectively prevents removal of the coating layer from portions of the workpiece; and

wherein the electrically conductive layer is not removed by the laser beam.

14. The method of claim 13, wherein the electrically conductive layer comprises a transparent conductive oxide.