Title of Invention

METHOD OF REMOVING AT LEAST PARTIALLY A LAYER OR COATING OF MATERIAL FROM A SUBSTRATE

Abstract A method for treating a substrate (14) having a layer or coating (16) of material thereon (such as for example a metal conductor coated with an insulating ‘enamel’) comprises the steps of directing a pulsed beam of laser (12) radiation at the substrate to cause an interaction or adjacent the interface between the layer or coating and the substrate, leading to local separation of the layer or coating. The removal is effected by creating an interaction effect at the interface between the substrate and the layer or coating to create an effect similar to a shockwave which causes local separation of the layer or coating at the interface.
Full Text FORM 2THE PATENTS ACT, 1970(39 of 1970)&The Patent Rules, 2003

COMPLETE SPECIFICATION [See Section 10 and Rule 13]
1. TITLE OF THE INVENTION
LASER REMOVAL OF LAYER OR COATING FROM A SUBSTRATE
2. APPLICANTS
(a) SPECTRUM TECHNOLOGIES PLC
(b) (c) a British company, of Western Avenue Bridgend, Mid Glamorgan CF31 3RT, UNITED KINGDOM,
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.





2
Laser Removal of Layer or Coating from a Substrate
This invention relates to methods and apparatus for removing a layer or
coating from a substrate and in particular, but not exclusively, to laser removal of
5 the insulating coating or "enamel" from a conductor as a preliminary step in
making an electrical connection by e.g. spot welding, soldering, crimping etc.
In one aspect this invention provides a method of treating a substrate
having a layer or coating of material thereon, at least partially to remove said
layer or coating, said method comprising the steps of:-
10 directing a pulsed beam of laser radiation at said substrate to cause an
interaction at or adjacent the interface between said layer or coating and said substrate, leading to local separation of said layer or coating.
Existing forms of laser wire stripper operate by vaporising the insulation
from the outside in whereas in the preferred embodiments of this invention the
15 removal is effected by creating an interaction effect at the interface between the
substrate and the layer or coating to create a Shockwave or the like which
causes local separation, rather than relying on a vaporisation technique.
Preferably the coating or layer is substantially transparent to said laser
radiation at its operating wavelength. The laser radiation may typically be of
20 wavelength between, say, 200 nm to 12 nm and may be conveniently generated
by an NdYag laser. The laser is preferably a Q-switched laser generating short pulses of typical pulse length between 1 nanosecond and 300 nanoseconds or higher. The pulse repetition rate of the laser is typically between 1 kHz and 30 kHz or higher.

3
In a particular preferred embodiment, the layer or coating includes a dielectric material such as a polyimide or plastics material. The substrate; may typically be a conductor such as copper or copper-based material.
Preferably, said pulsed radiation beam is effective also to etch or clean
5 the surface of the substrate adjacent the interface. This is particularly useful to
remove e.g. metal oxides to leave a bare surface particularly suitable for further processing.
Preferably, during treatment, the pulsed beam of laser radiation is moved
relative to the substrate in a scan direction (or vice versa) and at least one of the
10 following parameters is controlled to cause removal of a moving swath of said
layer or coating:-
scan rate
peak power of the laser
pulse repetition rate of the laser
15 spot size.
Preferably, said pulsed beam of radiation is scanned over a selected
region of said substrate in a first scanning stage to effect initial removal of said
layer or coating, and is then scanned over said region in a second scanning
stage to effect cleaning of residual debris.
20 In another aspect, there is provided apparatus for treating a substrate
having a layer or coating of material thereon, at least partially to remove said layer or coating, said apparatus comprising:-
means for directing a pulsed beam of laser radiation at said substrate to cause an interaction at or adjacent the interface between said layer or coating

4
and said substrate, leading to local separation of said layer or coating.
Whilst the invention has been described above, it extends to any
inventive combination of the features set out above or in the following
description,
5 The invention may be performed in various ways and for a better
understanding thereof specific non-limiting examples will now be given, reference being made to the accompanying drawing, in which:-
Figure 1 is a schematic view of a laser wire stripper in accordance with this invention.
10 In the Figure is shown a laser 10 which directs a pulsed beam 12 of laser
radiation towards a copper wire 14 having a coating 16 of polyimide material, to create an interface effect at the interface between the coating 16 and the wire 12 to cause the coating to fragment and to be lifted off by a Shockwave effect. Example 1
15 A copper wire enamelled with polyester (imide) and with/without
polyamide-imide top coat and with/without a bonding overcoat, is treated as set out below to remove the enamelling. An NdYag laser of wavelength 1064 nm is used having a constant average power rating of 60 W, and 85 kW peak and a spot size of about 20 μm. The spot size generates about 200 μm diameter
20 ablated area. The laser Is Q-switched to provide a pulsed beam of pulses of
between about 100 nanoseconds and 200 nanoseconds, which is scanned across the area to be stripped. The pulse repetition rate in this example is 3 kHz, the scan rate is approximately 1500 mm/sec and the peak power is of the order of 85 kW with a spot size of 20 μm. A typical pulse length of the laser is

5
between 100 nanoseconds and 200 nanoseconds.
At this wavelength the enamel is substantially transparent to the laser
radiation and the metal is highly reflective (97%) but nevertheless absorbs some
of the laser radiation. We found however that the pulse radiation generated an
5 effect adjacent the interface between the enamel and the underlying metal
similar to a Shockwave which caused local separation of the enamel from the wire as opposed to removal from the outside in. By suitably controlling the pulse repetition rate, the spot size and the scan rate we were able to remove large amounts of enamel to leave the metal surface bare. In addition it was noted that
10 the laser processing had a further benefit effect in terms of etching the metal
surface to remove metal oxide, thus rendering it suitable for soldering etc.
We found that, for a single scan, and with the particular equipment used in this example, the lower limit for the pulse repetition rate is in the range of 1 to 2 kHz at 1500 mm/sec scan rate which tends to give only just sufficient pulse
15 overlap. We found the upper limit to be about 5 kHz at constant power because
at higher frequencies the peak power tends to drop. Of course if the laser peak power is maintained in the preferred range of 50-100 kW then the pulse repetition rate can be further increased and in another example the laser was operated at 1 MW peak power, at a pulse repetition rate of 10 kHz, and a scan
20 rate of 2500 mm/sec.
Also we have found that in situations where the first scan does not achieve the full effect, an acceptable result can be achieved by double scanning, e.g. the peak power may be reduced to as low as 1 to 25 kW with a pulse repetition rate in the 10 to 30 kHz range, but then the laser must scan slower, at

6
about 100 mm/sec and the scan should be repeated.
Example 2
A laser was set up to operate with the following parameters:-
Repetition rate: 3.5 kHz
5 Scan speed: 400 mm/sec
Spot size: -50 urn
Wavelength: 1064'nm
Energy per pulse: 15 mJ
Pulse width: - 250 ns max
10 Peak power: -200KW
The spot size although nominally 50 urn, also affected the surrounding
area so the effective spot size in terms of the effect at the interface was about
100 μm to 200 μm. in this arrangement, the beam was scanned horizontally
across the wire to be stripped and prepared, that is perpendicular to the
15 longitudinal axis of the wire. The wire is scanned by the beam in a first pass in
accordance with the above parameters, at a pitch or spacing of about 100 um between adjacent scan lines.
The first pass removes most if not all of the coating off the wire, but may
leave some debris. In a second pass the wire is scanned with the pulsed laser
20 beam at a higher pulse rate (~ 8kHz) and at a higher scan speed (~ 1000
mm/sec) but otherwise with the same parameters as above.
It should be noted however that in some applications the second pass may not be required, because the nature of the coating and the interface effect may mean that the coating detaches in larger flakes, leaving little or no debris.

5

7
The various parameters are set out in Table 1. TABLE 1

Parameter Range Example 1 Example 2
Wavelength 200 nm to 12 μm 1064 nm 1064 nm
Pulse length 1 ns to 300 ns 100 ns to 200 ns 250 ns
Pulse repetition rate 1 kHz to 30 kHz 3.5 kHz 3.5 kHz and 8 kHz
Laser peak power 50KW-1MW 85 KW 200 KW
Scan rate 1 - 2500 mm/sec 1500 mm/sec 400 mm/secand1000 mm/sec
Actual spot size 20μm-100 μm 20 μm 50 μm

8
CLAIMS
1. A method of at least partially removing a layer or coating of
material from a substrate, said method comprising the steps of>
directing at said substrate a pulsed beam of laser radiation of wavelength
5 selected so that the coating or layer is substantially transparent to said laser
radiation, thereby to cause a Shockwave effect at or adjacent the interface
between said layer or coating and said substrate to effect local separation of
said layer or coating from said substrate.
2. A method according to Claim 1, wherein the laser radiation is of
10 wavelength of between 200 nm and 12 μm.
3. A method according to Claim 2, wherein said laser radiation is generated by an NdYag laser.
4. A method according to any of the preceding Claims, wherein said laser radiation is generated by a C02 laser.
15 5. A method according to any of the preceding Claims, wherein said
laser radiation is generated by a Q-switched laser.
6. A method according to any of the preceding Claims, wherein the
pulsed beam has pulses of pulse length between 1 nanosecond and 300
nanoseconds.
20 7. A method according to any of the preceding Claims, wherein the
pulse repetition rate of the pulsed beam is between 1 KHz and 30 KHz.
8. A method according to any of the preceding Claims, wherein the layer or coating includes a dielectric material.
9. A method according to any of the preceding Claims, wherein the

9
substrate is a conductor of copper or copper-based material.
10. A method according to any of the preceding Claims wherein the
layer or coating includes at least one metal oxide.
11. A method according to any of the preceding Claims, wherein said
5 pulsed beam of radiation is effective also to etch or clean the surface of the
substrate adjacent the interface.
12. A method according to any of the preceding Claims, wherein the
pulsed beam of laser radiation is scanned relative to the substrate in a scan
direction and at least one of the following parameters is controlled to cause
10 removal of a moving swath of said layer or coating:-
scan rate
peak power of the laser
pulse repetition rate of the laser
spot size.
15 13. A method according to any of the preceding Claims, wherein said
pulsed beam of laser radiation is scanned over said substrate along successive spaced scan lines.
14. A method according to Claim 12, wherein said pulsed beam of
radiation is scanned over a selected region in a first scanning stage to effect
20 initial removal of said layer or coating, and is then scanned over said region in a
second scanning stage to effect cleaning of residual debris.
15. Apparatus for at least partially removing a layer or coating of
material from a substrate, said apparatus comprising:-
means for directing at said substrate a pulsed beam of laser radiation of

10
wavelength selected so that the coating or layer is substantially transparent to said laser radiation, to cause a Shockwave effect at or adjacent the interface between said layer or coating and said substrate, to effect local separation of said layer or coating from said substrate.

ABSTRACT


A method for treating a substrate (14) having a layer or coating (16) of material thereon (such as for example a metal conductor coated with an insulating 'enamel') comprises the steps of directing a pulsed beam of laser (12) radiation at the substrate to cause an interaction or adjacent the interface between the layer or coating and the substrate, leading to local separation of the layer or coating. The removal is effected by creating an interaction effect at the interface between the substrate and the layer or coating to create an effect similar to a Shockwave which causes local separation of the layer or coating at the interface.

Documents:

00269-MUMNP-2006-ABSTRACT(8-3-2006).pdf

00269-MUMNP-2006-CANCELLED (CLAIMS)-(30-7-2008).pdf

00269-MUMNP-2006-CLAIMS(30-7-2008).pdf

00269-MUMNP-2006-CORRESPONDENCE(30-7-2008).pdf

00269-MUMNP-2006-DESCRIPTION(COMPLETE)-(8-3-2006).pdf

00269-MUMNP-2006-DRAWING(30-7-2008).pdf

00269-MUMNP-2006-FORM 1(10-7-2008).pdf

00269-mumnp-2006-form 2(8-3-2006).pdf

00269-MUMNP-2006-FORM 2(TITLE PAGE)-(8-3-2006).pdf

00269-MUMNP-2006-OTHER(30-7-2008).pdf

269-MUMNP-2006-ABSTRACT(10-7-2008).pdf

269-mumnp-2006-abstract(5-8-2008).doc

269-mumnp-2006-abstract(5-8-2008).pdf

269-mumnp-2006-abstract.doc

269-mumnp-2006-abstract.pdf

269-MUMNP-2006-CANCELLED PAGES 8-3-2006.pdf

269-MUMNP-2006-CANCELLED PAGES(10-7-2008).pdf

269-mumnp-2006-cancelled pages(5-8-2008).pdf

269-MUMNP-2006-CLAIMS 5-8-2008.pdf

269-MUMNP-2006-CLAIMS(10-7-2008).pdf

269-MUMNP-2006-CLAIMS(4-8-2008).pdf

269-mumnp-2006-claims(granted)-(5-8-2008).doc

269-mumnp-2006-claims(granted)-(5-8-2008).pdf

269-mumnp-2006-claims.doc

269-mumnp-2006-claims.pdf

269-MUMNP-2006-CORRESPONDENCE 10-7-2008.pdf

269-MUMNP-2006-CORRESPONDENCE 5-8-2008.pdf

269-MUMNP-2006-CORRESPONDENCE(10-7-2008).pdf

269-MUMNP-2006-CORRESPONDENCE(4-8-2008).pdf

269-mumnp-2006-correspondence(5-8-2008).pdf

269-mumnp-2006-correspondence(ipo)-(10-10-2008).pdf

269-mumnp-2006-correspondence-others.pdf

269-mumnp-2006-description (complete).pdf

269-MUMNP-2006-DESCRIPTION(COMPLETE)-(8-3-2006).pdf

269-mumnp-2006-drawing(5-8-2008).pdf

269-mumnp-2006-drawings.pdf

269-MUMNP-2006-FORM 1 10-7-2008.pdf

269-mumnp-2006-form 1(10-7-2008).pdf

269-mumnp-2006-form 13 10-7-2008.pdf

269-mumnp-2006-form 13(10-7-2008).pdf

269-mumnp-2006-form 13(30-7-2008).pdf

269-mumnp-2006-form 18(18-5-2006).pdf

269-mumnp-2006-form 2(8-3-2006).pdf

269-mumnp-2006-form 2(granted)-(5-8-2008).doc

269-mumnp-2006-form 2(granted)-(5-8-2008).pdf

269-MUMNP-2006-FORM 2(TITLE PAGE)-(8-3-2006).pdf

269-mumnp-2006-form 3(15-5-2006).pdf

269-mumnp-2006-form 3(23-6-2006).pdf

269-mumnp-2006-form 3(8-3-2006).pdf

269-mumnp-2006-form 5(8-3-2006).pdf

269-mumnp-2006-form-1.pdf

269-mumnp-2006-form-2.doc

269-mumnp-2006-form-2.pdf

269-mumnp-2006-form-3.pdf

269-mumnp-2006-form-5.pdf

269-mumnp-2006-form-pct-isa-210(8-3-2006).pdf

269-MUMNP-2006-OTHER DOCUMENT(10-7-2008).pdf

269-mumnp-2006-petition under rule 6(5)-(28-4-2006).pdf

269-mumnp-2006-power of authority(2-6-2006).pdf

abstract1.jpg


Patent Number 224343
Indian Patent Application Number 269/MUMNP/2006
PG Journal Number 06/2009
Publication Date 06-Feb-2009
Grant Date 10-Oct-2008
Date of Filing 08-Mar-2006
Name of Patentee SPECTRUM TECHNOLOGIES PLC
Applicant Address WESTERN AVENUE, BRIDGEND, MID GLAMORGAN CF31 3RT UK
Inventors:
# Inventor's Name Inventor's Address
1 THOMAS ADRIAN WESTERN AVENUE, BRIDGEND, MID GLAMORGAN CF31 3RT UK
2 DAVIES JONATHAN WESTERN AVENUE, BRIDGEND, MID GLAMORGAN CF31 3RT UK
3 DICKINSON PETER HUGH SPECTRUM TECHNOLOGIES PLC, WESTERN AVENUE, BRIDGEND, MID GLAMORGAN CF31 3RT UK
PCT International Classification Number B08B7/00
PCT International Application Number PCT/GB2004/002950
PCT International Filing date 2004-07-08
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0316347.4 2003-07-12 U.K.
2 0315947.2 2003-07-08 U.K.