LASER PROCESSING A WORKPIECE

• US 20110000898A1
• Filed: 02/10/2009
• Published: 01/06/2011
• Est. Priority Date: 02/23/2008
• Status: Active Grant

• Current Assignee: M-Solv Ltd.
• Original Assignee: M-Solv Ltd.
• Inventors: Rumsby, Philip Thomas
• Granted Patent: US 9,067,277 B2
• Time in Patent Office: Days
• US Class Current: 219/121.72
• CPC Class Codes: B23K 2101/34 Coated articles , e.g. plated or painted; Surface treated articles
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/048 by controlling the distance between laser head and workpiece
• CPC Class Codes: B23K 26/06 Shaping the laser beam, e.g. by masks or multi-focusing
• CPC Class Codes: B23K 26/0619 with spots located on opposed surfaces of the workpiece
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0648 comprising lenses
• CPC Class Codes: B23K 26/0665 by beam condensation on the workpiece, e.g. for focusing
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved

Abstract

A method is described for simultaneously writing patterns in thin films of material coated on the opposite sides of thin glass or plastic substrates by direct write, laser ablation. The substrates are fully or partially transparent to the laser radiation used and in addition the surfaces of the substrates are not assumed to be flat. Different registered patterns may be applied at the same time to opposite sides of the substrates.

Claims

1. A method of processing a workpiece, comprising a substrate having first and second films formed on its first and second surfaces, by direct-write laser ablation, in which the substrate is transparent to the laser radiation, the method comprising

providing a first laser beam delivery apparatus comprising a laser beam scanner and a lens unit;

positioning the lens unit of the first laser beam delivery apparatus to the first surface side of the substrate to direct-write the first film; and

direct-writing the first film with the laser beam from the lens unit being focussed at a spot short of the first film, whereby the laser beam is diverging as it impinges on the first film.

2. A method as in claim 1, wherein the distance of the focal spot of the laser beam from the first surface is approximately equal to the Rayleigh range of the laser beam.

3. A method as in claim 1, further comprising

providing a second laser beam delivery apparatus comprising a laser beam scanner and a lens unit;

positioning the lens unit of the second laser beam delivery apparatus to the second surface side of the substrate to direct-write the second film; and

direct-writing the second film with the laser beam from the lens unit being focussed at a spot short of the second film, whereby the laser beam is diverging as it impinges on the second film.

4. A method as in claim 1, wherein the distance of the focal spot of the laser beam from the second laser delivery apparatus from the second surface is approximately equal to the Rayleigh range of the laser beam.

5. A method as in claim 1, wherein the direct-writing of the first film and the direct-writing of the second film are carried out simultaneously.

6. A method as in claim 1, further comprising, during direct-writing a said film, adjusting the focus point of the corresponding lens unit to compensate for the non-flatness of the workpiece and maintain the focus point at the required distance from the corresponding surface.

7. A method as in claim 1, wherein a plurality of said laser beam delivery apparatuses are used in parallel on a said film.

8. A system for processing a workpiece, comprising a substrate having first and second films formed on its first and second sides, by direct write laser ablation in which the substrate is transparent to the laser radiation, the system comprising:

a first laser beam delivery apparatus comprising a laser beam scanner and a lens unit;

a carrier for the workpiece; and

mounting means for mounting the first laser beam delivery apparatus and the carrier for relative movement to permit the direct-writing of the first film, wherein the system is operable to direct-write the first film with the lens unit of the first laser beam delivery apparatus being focussed to at a spot short of the first film, whereby the laser beam is diverging as it impinges on the first film.

9. A system as in claim 8, wherein the distance of the focal spot of the laser beam from the first surface is approximately equal to the Rayleigh range of the laser beam.

10. A system as in claim 8, further comprising a second laser beam delivery apparatus comprising a laser beam scanner and a lens unit, the mounting means being further configured to mount the second laser beam delivery apparatus and the carrier for relative movement to permit the direct-writing of the second film, wherein the system is operable to direct-write the second film with the lens unit of the second laser beam delivery apparatus being focussed at a spot short of the second film, whereby the laser beam is diverging as it impinges on the second film.

11. A system as in claim 10, wherein the direct-writing of the first film and the direct-writing of the second film are carried out simultaneously.

12. A system as in claim 8, further comprising imaging means to determine the distance of a said lens unit from the adjacent surface of the substrate, and a controller operable, responsive to said distance determination, to adjust the focus of said lens unit to maintain the focus point of the corresponding laser beam at the required distance from the corresponding substrate surface.

13. A system as in claim 8, further comprising a plurality of said laser beam delivery apparatuses mounted for use in parallel on a said film.

14. A system as in claim 8, wherein the mounting means comprises a pair of linear stage units to allow the relative motion in two axes between the substrate and said scanner and lens units.