Ablation Cutting of a Workpiece by a Pulsed Laser Beam

• US 20160129526A1
• Filed: 12/28/2015
• Published: 05/12/2016
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Trumpf Laser- und Systemtechnik GmbH (TRUMPF SE + Co. KG)
• Original Assignee: Trumpf Laser- und Systemtechnik GmbH (TRUMPF SE + Co. KG)
• Inventors: Russ, Simone, Aalderink, Dennis
• Granted Patent: US 10,639,741 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/54 Glass
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/0869 Devices involving movement of the laser head in at least one axial direction
• CPC Class Codes: B23K 26/352 for surface treatment
• CPC Class Codes: B23K 26/3584 Increasing rugosity, e.g. roughening
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/38 by boring or cutting
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B23K 26/402 involving non-metallic material, e.g. isolators
• CPC Class Codes: C03B 33/0222 Scoring using a focussed radiation beam, e.g. laser

Abstract

A method for ablating a workpiece by a pulsed laser beam includes pretreating a workpiece surface of the workpiece by moving the pulsed laser beam over the workpiece surface along a surface path, first consecutive laser pulses of the pulsed laser beam having a first pulse overlap on the workpiece surface in a path direction, and ablating the pretreated workpiece surface by moving the pulsed laser beam over the workpiece surface along the surface path multiple times. The second consecutive laser pulses of the pulsed laser beam have a second pulse overlap on the workpiece surface in the path direction, and the second pulse overlap is less than the first pulse overlap.

Claims

1. A method comprising:

pretreating a workpiece surface of a workpiece by moving a first pulsed laser beam over the workpiece surface along a surface path, wherein first consecutive laser pulses of the first pulsed laser beam have a first pulse overlap on the workpiece surface in a path direction; and

ablating the pretreated workpiece surface by moving a second pulsed laser beam over the workpiece surface along the surface path multiple times, wherein second consecutive laser pulses of the second pulsed laser beam have a second pulse overlap on the workpiece surface in the path direction, and wherein the second pulse to overlap is less than the first pulse overlap.

2. The method of claim 1, wherein the first consecutive laser pulses and the second consecutive laser pulses have a same pulse power and a same diameter on the workpiece surface.

3. The method of claim 1, wherein the first and second pulse overlaps are achieved by changing at least one of a pulse frequency or an overmovement speed.

4. The method of claim 1, wherein the first pulse overlap is more than 90%.

5. The method of claim 4, wherein the first pulse overlap is more than 95%.

6. The method of claim 1, wherein the second pulse overlap is less than 70%.

7. The method of claim 6, wherein the second pulse overlap is less than 50%.

8. The method of claim 1, further comprising:

pretreating the workpiece surface by moving the first pulsed laser beam over the workpiece surface along a plurality of surface paths in the path direction, the plurality of surface paths being offset laterally from each other.

9. The method of claim 1, further comprising:

ablating the pretreated workpiece surface by moving the second pulsed laser beam over the workpiece surface along a plurality of surface paths in the path direction, the plurality of surface paths being laterally from each other.

10. The method of claim 1, wherein pretreating a workpiece surface of the workpiece comprises:

moving the first pulsed laser beam over the workpiece surface along the surface path no more than twice.

11. The method of claim 1, wherein the first pulsed laser beam and the second pulsed laser beam are generated with a same laser.

12. The method of claim 1, wherein pretreating a workpiece surface of the workpiece comprises:

reducing transmission of a workpiece region near the workpiece surface.

13. The method of claim 12, wherein pretreating a workpiece surface of the workpiece comprises:

roughening the workpiece surface by the first pulsed laser beam.

14. The method of claim 1, wherein ablating the pretreated workpiece surface comprises:

repeating the ablating for a plurality of times until the workpiece is parted completely along the surface path.

15. The method of claim 1, further comprising:

parting the workpiece completely on the ablated surface path by a mechanical ablation method.

16. The method of claim 15, wherein the mechanical ablation method includes a scratching process.

17. The method of claim 1, further comprising:

carrying out the pretreating and ablating on both sides of the workpiece along the same surface path.

18. The method of claim 17, further comprising:

carrying out the pretreating and ablating on a first side of the workpiece along the surface path;

then

carrying out the pretreating and ablating on a second, reverse side of the workpiece along the same surface path.

19. The method of claim 18, further comprising:

turning the workpiece over after carrying out the pretreating and ablating on the first side of the workpiece,

wherein a single laser is used for carrying out the pretreating and ablating on the first side and on the second side.

20. The method of claim 1, wherein the workpiece is an optically transparent workpiece.