GB2169496A - Cleaning metal surfaces - Google Patents

Cleaning metal surfaces Download PDF

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Publication number
GB2169496A
GB2169496A GB08501028A GB8501028A GB2169496A GB 2169496 A GB2169496 A GB 2169496A GB 08501028 A GB08501028 A GB 08501028A GB 8501028 A GB8501028 A GB 8501028A GB 2169496 A GB2169496 A GB 2169496A
Authority
GB
United Kingdom
Prior art keywords
laser
surface
contact
metal surface
method
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08501028A
Other versions
GB8501028D0 (en
GB2169496B (en
Inventor
Kenneth George Snowdon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
STC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by STC PLC filed Critical STC PLC
Priority to GB08501028A priority Critical patent/GB2169496B/en
Publication of GB8501028D0 publication Critical patent/GB8501028D0/en
Publication of GB2169496A publication Critical patent/GB2169496A/en
Application granted granted Critical
Publication of GB2169496B publication Critical patent/GB2169496B/en
Application status is Expired legal-status Critical

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Classifications

    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23GCLEANING OR DEGREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G5/00Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B08CLEANING
    • B08BCLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00Cleaning by methods not provided for in a single other subclass or a single group in this subclass
    • B08B7/0035Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like
    • B08B7/0042Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like by laser

Abstract

A reflective metal surface, e.g. an electrical contact surface, is cleaned by exposing the surface to pulsed laser radiation. The progress of the evaporation can be monitored by examination of the emission spectrum of the transient plasma produced by each laser pulse. An apparatus for carrying out the process is also described.

Description

SPECIFICATION Cleaning metal surfaces This invention relates to electrical contacts, and in particular to a method and apparatus for removing 'contaminant deposits from such contacts.

Electrical contacts, e.g. for use in switches or relays, are frequently contaminated with organic and inorganic materials during manufacture. The presence of this contamination on the contact surface can resuit in carbonisation and/ortarnishing during subsequent use. This in turn can lead to a number of contact faults, particularly on unacceptably high contact resistance.

Various methods have been proposed for cleaning contacts prior to use in high reliability applications.

Typically the contacts are treated with a solvent which removes soluble organic residues. However such treatment is not fully effective as polymeric and/or inorganic materials may still adhere to the contact surface.

The object of the present invention is to minimise or to overcome this disadvantage.

According to one aspect of the invention there is provided a method of cleaning a reflective metal surface, the method including exposing the surface to pulsed coherent radiation of sufficient intensity to vapourise contaminant materials adherent to the metal surface.

According to another aspect of the invention there is provided an apparatus for removing contaminant materials from a reflective metal surface, the apparatus including a pulsed laser, meansforfocussing the laser output on to the metal surface, spectroscopic means for detecting non-metallic elements in the material evaporated from the metal surface by the laser beam, and feedback means for disabling the laser when said non metallic elements are absent from the evaporated material.

An embodiment ofthe invention will now be described with reference to the accompanying drawing in which the single figure is a schematic diagram of a contact cleaning apparatus.

Referring to the drawing, the contact cleaning apparatus includes an ultraviolet laser 11 of the pulsed type driven buy a power supply 12 and provided with a converging optical system 13, e.g. a lens, whereby the laser output may be focussed on to the surface of a contact 14. Typically we employ a krypton fluoride gas laser having a wavelength of 249 nm for this purpose, but it will be apparentthatthe technique is not limited to this particular laser system. The constraints on the laser are that it should provide a sufficient energy densityto effectvaporisation and that it should have a wavelength at which the contaminant materials are absorbent.We have found that a surface energy density of 0.1 J/cm2 to 0.8 J/cm2 is sufficient to provide vaporisation of surface deposits. As the metal surface is reflective there is substantially no depletion of the contact material.

Advantageously the evaporation process may be monitored to establish the pointatwhich removal of contaminant material is complete. After each laser pulse a transient incandescent plasma is produced at the evaporation site. The emission spectrum of this plasma is of course characteristicofthose elements present. Lightfrom the plasma is received by a photodetector 1 4via a filter 15 whose passband corresponds to the emission lines ofthe non-metallic contaminant elements, e.g. carbon and/orsulphur.

The photodetector output is coupled via amplifier 16 to a control circuit 17 which circuitdisablesthe laser when the characteristic emission lines are no longer present, i.e. when all the contaminant material has been depleted. The contact 14 is then removed for further processing.

Although the technique has been described in relation to electrical contacts it will be appreciated that it is not so limited and that it can be applied to other reflective metal surfaces. In particularthe technique can be used with advantage forthe treatment of connector contacts and PCB edge contacts.

1. A method of cleaning a reflective metal surface, the method including exposing the surface to pulsed coherent radiation of sufficient intensity to vapourise contaminant materials adherentto the metal surface.

2. A method as claimed in claim 1 wherein said radiation is provided by an ultraviolet laser.

3. A method as claimed in claim 2, wherein said laser is a krypton fluoride laser.

4. Amethodofcleaninga reflectivemetalsurface substantially as described herein with reference to the accompanying drawings.

5. A method as claimed in claim 1,2 or 3, wherein the laser provides a surface energy density of 0.1 to 0.8 J/cm2.

6. An appparatusforremoving contaminant materialsfrom a reflective metal surface, the apparatus including a pulsed laser, meansforfocussingthe laser output on to the metal surface, spectroscopic means for detecting non-metallic elements in the material evaporated from the metal surfacebythelaserbeam, and feedback means for disabling the laser when said non metallic elements are absentfrom the evaporated material.

7. An apparatus as claimed in claim 6, wherein said laser is an ultraviolet laser.

8. An apparatus as claimed in claim 7, wherein said laser is a krypton fluoride laser.

9. An apparatus for cleaning a reflective metal surface substantially as described herein with reference to the accompanying drawings.

10. An electrical contact treated by a method as claimed in any one of claims 1 to 5.

11. A printed circuit board treated by.a method as claimed in any one of claims 1 to 5.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cleaning metal surfaces This invention relates to electrical contacts, and in particular to a method and apparatus for removing 'contaminant deposits from such contacts. Electrical contacts, e.g. for use in switches or relays, are frequently contaminated with organic and inorganic materials during manufacture. The presence of this contamination on the contact surface can resuit in carbonisation and/ortarnishing during subsequent use. This in turn can lead to a number of contact faults, particularly on unacceptably high contact resistance. Various methods have been proposed for cleaning contacts prior to use in high reliability applications. Typically the contacts are treated with a solvent which removes soluble organic residues. However such treatment is not fully effective as polymeric and/or inorganic materials may still adhere to the contact surface. The object of the present invention is to minimise or to overcome this disadvantage. According to one aspect of the invention there is provided a method of cleaning a reflective metal surface, the method including exposing the surface to pulsed coherent radiation of sufficient intensity to vapourise contaminant materials adherent to the metal surface. According to another aspect of the invention there is provided an apparatus for removing contaminant materials from a reflective metal surface, the apparatus including a pulsed laser, meansforfocussing the laser output on to the metal surface, spectroscopic means for detecting non-metallic elements in the material evaporated from the metal surface by the laser beam, and feedback means for disabling the laser when said non metallic elements are absent from the evaporated material. An embodiment ofthe invention will now be described with reference to the accompanying drawing in which the single figure is a schematic diagram of a contact cleaning apparatus. Referring to the drawing, the contact cleaning apparatus includes an ultraviolet laser 11 of the pulsed type driven buy a power supply 12 and provided with a converging optical system 13, e.g. a lens, whereby the laser output may be focussed on to the surface of a contact 14. Typically we employ a krypton fluoride gas laser having a wavelength of 249 nm for this purpose, but it will be apparentthatthe technique is not limited to this particular laser system. The constraints on the laser are that it should provide a sufficient energy densityto effectvaporisation and that it should have a wavelength at which the contaminant materials are absorbent.We have found that a surface energy density of 0.1 J/cm2 to 0.8 J/cm2 is sufficient to provide vaporisation of surface deposits. As the metal surface is reflective there is substantially no depletion of the contact material. Advantageously the evaporation process may be monitored to establish the pointatwhich removal of contaminant material is complete. After each laser pulse a transient incandescent plasma is produced at the evaporation site. The emission spectrum of this plasma is of course characteristicofthose elements present. Lightfrom the plasma is received by a photodetector 1 4via a filter 15 whose passband corresponds to the emission lines ofthe non-metallic contaminant elements, e.g. carbon and/orsulphur. The photodetector output is coupled via amplifier 16 to a control circuit 17 which circuitdisablesthe laser when the characteristic emission lines are no longer present, i.e. when all the contaminant material has been depleted. The contact 14 is then removed for further processing. Although the technique has been described in relation to electrical contacts it will be appreciated that it is not so limited and that it can be applied to other reflective metal surfaces. In particularthe technique can be used with advantage forthe treatment of connector contacts and PCB edge contacts. CLAIMS
1. A method of cleaning a reflective metal surface, the method including exposing the surface to pulsed coherent radiation of sufficient intensity to vapourise contaminant materials adherentto the metal surface.
2. A method as claimed in claim 1 wherein said radiation is provided by an ultraviolet laser.
3. A method as claimed in claim 2, wherein said laser is a krypton fluoride laser.
4. Amethodofcleaninga reflectivemetalsurface substantially as described herein with reference to the accompanying drawings.
5. A method as claimed in claim 1,2 or 3, wherein the laser provides a surface energy density of 0.1 to 0.8 J/cm2.
6. An appparatusforremoving contaminant materialsfrom a reflective metal surface, the apparatus including a pulsed laser, meansforfocussingthe laser output on to the metal surface, spectroscopic means for detecting non-metallic elements in the material evaporated from the metal surfacebythelaserbeam, and feedback means for disabling the laser when said non metallic elements are absentfrom the evaporated material.
7. An apparatus as claimed in claim 6, wherein said laser is an ultraviolet laser.
8. An apparatus as claimed in claim 7, wherein said laser is a krypton fluoride laser.
9. An apparatus for cleaning a reflective metal surface substantially as described herein with reference to the accompanying drawings.
10. An electrical contact treated by a method as claimed in any one of claims 1 to 5.
11. A printed circuit board treated by.a method as claimed in any one of claims 1 to 5.
GB08501028A 1985-01-16 1985-01-16 Cleaning metal surfaces Expired GB2169496B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08501028A GB2169496B (en) 1985-01-16 1985-01-16 Cleaning metal surfaces

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB08501028A GB2169496B (en) 1985-01-16 1985-01-16 Cleaning metal surfaces
DE19863600591 DE3600591A1 (en) 1985-01-16 1986-01-11 and apparatus for removing contaminants from the surface of metal by means of laser beams, and so treated surfaces procedure

Publications (3)

Publication Number Publication Date
GB8501028D0 GB8501028D0 (en) 1985-02-20
GB2169496A true GB2169496A (en) 1986-07-16
GB2169496B GB2169496B (en) 1987-12-23

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DE (1) DE3600591A1 (en)
GB (1) GB2169496B (en)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2641550A1 (en) * 1988-09-23 1990-07-13 Mo Textilny I Imen fibrous materials cleaning method of removing impurities and plant and apparatus for implementing such process
EP0461843A2 (en) * 1990-06-11 1991-12-18 Agency Of Industrial Science And Technology Methods of modifying metallic surfaces
US5151135A (en) * 1989-09-15 1992-09-29 Amoco Corporation Method for cleaning surfaces using UV lasers
WO1995011764A1 (en) * 1993-10-26 1995-05-04 Saint Gobain Emballage Method and device for cleaning solid elements
US5626778A (en) * 1995-04-28 1997-05-06 International Business Machines Corporation Multi-wavelength programmable laser processing mechanisms and apparatus utilizing spectrometer verification
GB2316528A (en) * 1996-08-14 1998-02-25 Commissariat Energie Atomique Process for cleaning or decontaminating an object by means of an ultraviolet laser beam together with apparatus for implementing the process
EP0905762A1 (en) * 1997-09-30 1999-03-31 SGS-THOMSON MICROELECTRONICS S.r.l. Method for removing moulding residues in the fabrication of plastic packages for semiconductor devices
US5928533A (en) * 1996-03-01 1999-07-27 Pirelli Coordinamento Pneumatici S.P.A. Method and apparatus for cleaning vulcanization molds for elastomer material articles
NL1016334C2 (en) * 2000-10-05 2002-04-08 Boschman Tech Bv A method of using a laser cutting of a composite structure having one or more electronic components.
WO2002029853A2 (en) * 2000-10-05 2002-04-11 Boschman Technologies B.V. Method for cutting a composite structure comprising one or more electronic compnents using a laser
EP1342510A2 (en) * 2002-03-09 2003-09-10 MTU Aero Engines GmbH Process for stripping of engine elements and device for process execution
WO2004019020A1 (en) * 2002-08-22 2004-03-04 The Secretary Of State For Defence Method and apparatus for stand-off chemical detection
DE10313521A1 (en) * 2002-12-18 2004-07-08 Geringer, Michael Arrangement for removing burrs from components in lead frames has image processing system with camera(s) for detecting component orientation/position, controlling laser beam along edge to be deburred
EP2666555A1 (en) * 2012-05-22 2013-11-27 Unison Industries LLC Method of preparing material for welding

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02504238A (en) * 1987-04-01 1990-12-06
DE3721940C2 (en) * 1987-07-02 1989-04-06 Ibm Deutschland Gmbh, 7000 Stuttgart, De
US5103073A (en) * 1987-08-28 1992-04-07 Danilov Viktor A Device for laser treatment of an object
DE3932328A1 (en) * 1989-09-28 1991-04-11 Opel Adam Ag A method for processing by friction highly stressed surfaces in internal combustion engines and apparatus for performing the method
DE4142855A1 (en) * 1991-12-20 1993-07-01 Electronicon Gmbh I L Preferentially etching metal coatings on plastic or paper foil - using pulsed laser beam operating in ultraviolet range
DE4241575A1 (en) * 1992-12-10 1994-06-16 Baldwin Gegenheimer Gmbh Printing roller cleaning - uses laser beam to detach dirt and residue from surface without affecting surface character
DE4301410A1 (en) * 1993-01-20 1994-07-21 Baldwin Gegenheimer Gmbh Printing machine cleaning device
DE4320408C2 (en) * 1993-06-21 1998-02-19 Fraunhofer Ges Forschung A method for process monitoring and control during the surface machining of workpieces with pulsed laser radiation
DE19617388C1 (en) * 1996-04-30 1997-05-28 Siemens Ag Laser machining process monitoring system
DE10130402A1 (en) * 2001-06-23 2003-01-02 Bayerische Motoren Werke Ag A method for monitoring a pre-treatment
DE10222117B4 (en) * 2002-05-17 2004-09-16 W&H Dentalwerk Bürmoos Gesellschaft m.b.H. Dental-medical laser processing apparatus for plasma-induced ablation
CH698238B1 (en) * 2005-07-07 2009-06-30 Main Man Inspiration Ag Device for the continuous surface cleaning a rotatable casting rolls of a strip-casting machine.
CN103792215B (en) * 2014-01-24 2016-08-17 国电科学技术研究院 A rapid method for measuring the content of carbon in the steel
CN106881311A (en) * 2017-03-29 2017-06-23 中国人民解放军装甲兵工程学院 Underwater metal surface contaminant laser cleaning waterproof device and application thereof

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GB1127715A (en) * 1966-04-27 1968-09-18 Hellmut Schneider Method and apparatus for producing sonic or ultrasonic energy or heat at surfaces
GB1585609A (en) * 1976-10-07 1981-03-11 Lasag G Method of removing material from a workpiece
GB2061164A (en) * 1979-10-25 1981-05-13 Langen R Method of and apparatus for removing rust
EP0091646A1 (en) * 1982-04-14 1983-10-19 Westinghouse Electric Corporation Laser decontamination method
GB2118028A (en) * 1982-04-05 1983-10-26 Maxwell Lab Decontaminating surfaces

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GB1127715A (en) * 1966-04-27 1968-09-18 Hellmut Schneider Method and apparatus for producing sonic or ultrasonic energy or heat at surfaces
GB1585609A (en) * 1976-10-07 1981-03-11 Lasag G Method of removing material from a workpiece
GB2061164A (en) * 1979-10-25 1981-05-13 Langen R Method of and apparatus for removing rust
GB2118028A (en) * 1982-04-05 1983-10-26 Maxwell Lab Decontaminating surfaces
EP0091646A1 (en) * 1982-04-14 1983-10-19 Westinghouse Electric Corporation Laser decontamination method

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Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2641550A1 (en) * 1988-09-23 1990-07-13 Mo Textilny I Imen fibrous materials cleaning method of removing impurities and plant and apparatus for implementing such process
US5151135A (en) * 1989-09-15 1992-09-29 Amoco Corporation Method for cleaning surfaces using UV lasers
EP0461843A2 (en) * 1990-06-11 1991-12-18 Agency Of Industrial Science And Technology Methods of modifying metallic surfaces
EP0461843A3 (en) * 1990-06-11 1993-03-17 Agency Of Industrial Science And Technology Methods of modifying metallic surfaces
WO1995011764A1 (en) * 1993-10-26 1995-05-04 Saint Gobain Emballage Method and device for cleaning solid elements
FR2711557A1 (en) * 1993-10-26 1995-05-05 Saint Gobain Emballage Method and apparatus for cleaning solid elements.
US5643367A (en) * 1993-10-26 1997-07-01 Saint Gobain Emballage Method and device for cleaning solid elements
US5626778A (en) * 1995-04-28 1997-05-06 International Business Machines Corporation Multi-wavelength programmable laser processing mechanisms and apparatus utilizing spectrometer verification
US5928533A (en) * 1996-03-01 1999-07-27 Pirelli Coordinamento Pneumatici S.P.A. Method and apparatus for cleaning vulcanization molds for elastomer material articles
US6113707A (en) * 1996-03-01 2000-09-05 Pirelli Coordinamento Pneumatici Spa Method and apparatus for cleaning vulcanization molds for elastomer material articles
GB2316528B (en) * 1996-08-14 2000-07-12 Commissariat Energie Atomique Process for cleaning or decontaminating an object an object by means of an ultraviolet laser beam together with apparatus for implementing the process
GB2316528A (en) * 1996-08-14 1998-02-25 Commissariat Energie Atomique Process for cleaning or decontaminating an object by means of an ultraviolet laser beam together with apparatus for implementing the process
US6468356B1 (en) 1997-09-30 2002-10-22 Stmicroelectronics S.R.L. Method for removing molding residues in the fabrication of plastic packages for semiconductor devices
EP0905762A1 (en) * 1997-09-30 1999-03-31 SGS-THOMSON MICROELECTRONICS S.r.l. Method for removing moulding residues in the fabrication of plastic packages for semiconductor devices
NL1016334C2 (en) * 2000-10-05 2002-04-08 Boschman Tech Bv A method of using a laser cutting of a composite structure having one or more electronic components.
WO2002029853A2 (en) * 2000-10-05 2002-04-11 Boschman Technologies B.V. Method for cutting a composite structure comprising one or more electronic compnents using a laser
WO2002029853A3 (en) * 2000-10-05 2002-08-08 Boschman Tech Bv Method for cutting a composite structure comprising one or more electronic compnents using a laser
EP1342510A3 (en) * 2002-03-09 2005-06-22 MTU Aero Engines GmbH Process for stripping of engine elements and device for process execution
EP1342510A2 (en) * 2002-03-09 2003-09-10 MTU Aero Engines GmbH Process for stripping of engine elements and device for process execution
WO2004019020A1 (en) * 2002-08-22 2004-03-04 The Secretary Of State For Defence Method and apparatus for stand-off chemical detection
US7298475B2 (en) 2002-08-22 2007-11-20 The Secretary Of State For Defence Method and apparatus for stand-off chemical detection
DE10313521A1 (en) * 2002-12-18 2004-07-08 Geringer, Michael Arrangement for removing burrs from components in lead frames has image processing system with camera(s) for detecting component orientation/position, controlling laser beam along edge to be deburred
DE10313521B4 (en) * 2002-12-18 2006-05-11 Geringer, Michael Device and method of Spritzgrats to housing sides arranged in a lead frame for removing components
EP2666555A1 (en) * 2012-05-22 2013-11-27 Unison Industries LLC Method of preparing material for welding
US8859935B2 (en) 2012-05-22 2014-10-14 General Electric Company Method of preparing material for welding

Also Published As

Publication number Publication date
DE3600591A1 (en) 1986-07-17
GB8501028D0 (en) 1985-02-20
GB2169496B (en) 1987-12-23

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