EP0784514B1 - Method of and arrangement for applying a fluid to a surface - Google Patents

Method of and arrangement for applying a fluid to a surface Download PDF

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Publication number
EP0784514B1
EP0784514B1 EP95921103A EP95921103A EP0784514B1 EP 0784514 B1 EP0784514 B1 EP 0784514B1 EP 95921103 A EP95921103 A EP 95921103A EP 95921103 A EP95921103 A EP 95921103A EP 0784514 B1 EP0784514 B1 EP 0784514B1
Authority
EP
European Patent Office
Prior art keywords
needle
fluid
arrangement
vibration
subjected
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.)
Expired - Lifetime
Application number
EP95921103A
Other languages
German (de)
French (fr)
Other versions
EP0784514A1 (en
Inventor
Wessel Joris Wesseling
Nicolaas Johannes Anthonius Van Veen
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
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 Koninklijke Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0784514A1 publication Critical patent/EP0784514A1/en
Application granted granted Critical
Publication of EP0784514B1 publication Critical patent/EP0784514B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
    • B05B15/50—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
    • B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
    • B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations

Definitions

  • the invention relates to a method of applying a fluid to a surface, the pressurised fluid being applied from a container to the surface through a hollow needle.
  • the invention also relates to an arrangement for carrying out said method.
  • a frequently occurring problem with this known method is clogging of the hollow needle.
  • the fluid is a solder paste clogging is caused particularly by segregation of the solder paste near the transition from the container to the needle.
  • the flux then separates from the soldering powder globules because the specific mass of the soldering powder globules is higher than that of the flux. This results in solder powder globules accumulating in the lower part of the container and thereby obstructing the entrance to the needle.
  • the paste is subjected to pressure impulses in order to apply the paste, the solder powder globules are compressed additionally, which promotes the clogging process.
  • the fluid is an adhesive
  • clogging is caused by premature curing of the adhesive, particularly because pressure pulses cause a rise in temperature.
  • the pressure to which the fluid is subjected may result merely from the hydrostatic pressure of the fluid itself or, in addition, an external pressure produced by separate pressure means.
  • the method in accordance with the invention is characterised in that the needle is subjected to a longitudinal vibration during the application of fluid.
  • a variant of the above method is characterised in that the needle is subjected to a vibration having a frequency between 1 and 100 Hz and the duration of the needle movement towards the surface is longer than the duration of the needle movement away from the surface.
  • the fluid is subjected to a pumping action directed towards the surface to which the fluid is applied. Applying the fluid to the surface can even be effected exclusively by means of the pumping action described above. When external pressure is applied the pumping action allows this pressure to be smaller than in the case that the needle is not subjected to a longitudinal vibration.
  • the vibration amplitude is preferably of the same order of magnitude as the grain size of solder globules in the paste. This enables solder globules to be applied one by one.
  • Another variant of the method is characterised in that the needle is subjected to a vibration having a frequency between 1 and 30 kHz. At these high frequencies the fluid in the needle cannot follow the needle movements owing to the mass inertia. This reduces the friction between the needle and the fluid, as a result of which the output per unit of time is increased.
  • the vibration amplitude is preferably of the same order of magnitude as the grain size of the solder globules in the paste.
  • An arrangement for applying a fluid to a surface comprising a hollow needle via which, in operation, the pressurised fluid is applied to the surface, is characterised in that the arrangement comprises a vibration device arranged to be coupled to the needle so as to make the needle vibrate longitudinally.
  • the vibration device comprises a piezoelectric transducer connected to the needle.
  • a piezoelectric transducer connected to the needle.
  • This enables the needle to be set into vibration in a constructionally simple manner.
  • other vibration devices are possible, such as electromagnetic or mechanical transducers.
  • the arrangement with which the method is carried out comprises a container 1 having an outlet 2.
  • the vibration device 3 has a housing 4, which accommodates a piezoelectric transducer 5.
  • This transducer comprises a flat disc whose edge is clamped between housing portions 6.
  • a hollow needle 7 extends through the centre of the disc and perpendicularly to the disc. The needle is fixedly connected to the disc.
  • the housing 4 has a connecting sleeve 8 by which the housing can be secured to the outlet 2 of the container 1, for example by screw-thread means.
  • the hollow needle extends through the outlet 2 into the container.
  • a sealing ring 9 is interposed between the housing and the hollow needle.
  • a tube 10 connects the container to a pressure generator 11.
  • the arrangement operates as follows: Under the influence of pressure the solder paste 12 in the container is forced through the hollow needle 7 and is applied to a surface 13 of a printed circuit board 14. The pressure is generally applied in a pulsating fashion.
  • the piezoelectric transducer 5 is set into vibration by a voltage, causing the hollow needle 7 to vibrate in its longitudinal direction. If the needle vibrates with a comparatively low frequency (1 - 100 Hz), the voltage can be modulated in such a manner that the needle moves slowly towards the surface and returns rapidly. This can be achieved by means of a sawtooth voltage. In this way the paste is subjected to a pumping action which facilitates the application of the paste. This is illustrated diagrammatically by means of Fig. 2.
  • the solder paste in the needle cannot follow the rapid movements of the needle. Satisfactory results are also obtained with a frequency of 6 - 7 kHz, a pressure on the paste of 0.5 bar, and a needle diameter of 0.2 mm.
  • the paste output is approximately 40 % higher than when the needle is not vibrated.
  • Fig. 3 shows another vibration device.
  • the needle 7 is subjected to a low-frequency longitudinal vibration by means of a cam mechanism 15.
  • An arm 16 is pivotally connected to the housing 4 of the vibration device 3.
  • the needle 7 has a pin 17 engaging an opening 18 in the arm.
  • the arm 16 extends transversely of the needle 7.
  • a rotating cam 19 sets the arm 16 and hence the needle 7 into longitudinal vibration.
  • a spring 20 urges the arm 16 against the cam surface 21 of the cam.
  • the cam surface can be chosen in such a manner that the needle movement away from the surface of a printed circuit board is faster the needle movement towards this surface, which again produces said pumping action.
  • the pressure generator is preferably a fluid pump, for example an axial flow pump, because such a pump produces a well-defined pressure.
  • a fluid pump for example an axial flow pump
  • an air-pressure pump is also possible.
  • the pump may directly form part of the arrangement or may be external to this arrangement and be connected to the container via flexible tubes.
  • the container may also be external and may be connected to the needle via a flexible tube. This reduces the overall mass of the moving system, enabling the speed to be increased.

Landscapes

  • Electric Connection Of Electric Components To Printed Circuits (AREA)

Description

The invention relates to a method of applying a fluid to a surface, the pressurised fluid being applied from a container to the surface through a hollow needle. The invention also relates to an arrangement for carrying out said method.
Such a method is known from DE-A-37 28 054.
A frequently occurring problem with this known method is clogging of the hollow needle. When the fluid is a solder paste clogging is caused particularly by segregation of the solder paste near the transition from the container to the needle. The flux then separates from the soldering powder globules because the specific mass of the soldering powder globules is higher than that of the flux. This results in solder powder globules accumulating in the lower part of the container and thereby obstructing the entrance to the needle. When the paste is subjected to pressure impulses in order to apply the paste, the solder powder globules are compressed additionally, which promotes the clogging process. When the fluid is an adhesive, clogging is caused by premature curing of the adhesive, particularly because pressure pulses cause a rise in temperature. The pressure to which the fluid is subjected may result merely from the hydrostatic pressure of the fluid itself or, in addition, an external pressure produced by separate pressure means.
It is an object of the invention to preclude clogging of the hollow needle, as far as this is possible.
To this end the method in accordance with the invention is characterised in that the needle is subjected to a longitudinal vibration during the application of fluid.
It has been found that when the needle vibrates in the above-mentioned manner the homogeneous distribution of the fluid components remains satisfactory. The fluid better retains its state of fluidity. A homogeneous distribution prevents clogging of the needle, as a result of which the process need not be interrupted to clean or replace the needle.
A variant of the above method is characterised in that the needle is subjected to a vibration having a frequency between 1 and 100 Hz and the duration of the needle movement towards the surface is longer than the duration of the needle movement away from the surface. As a result, the fluid is subjected to a pumping action directed towards the surface to which the fluid is applied. Applying the fluid to the surface can even be effected exclusively by means of the pumping action described above. When external pressure is applied the pumping action allows this pressure to be smaller than in the case that the needle is not subjected to a longitudinal vibration. When the above method is used for the application of a solder paste to a surface, the vibration amplitude is preferably of the same order of magnitude as the grain size of solder globules in the paste. This enables solder globules to be applied one by one.
Another variant of the method is characterised in that the needle is subjected to a vibration having a frequency between 1 and 30 kHz. At these high frequencies the fluid in the needle cannot follow the needle movements owing to the mass inertia. This reduces the friction between the needle and the fluid, as a result of which the output per unit of time is increased.
When the method is used for applying solder paste to a surface the vibration amplitude is preferably of the same order of magnitude as the grain size of the solder globules in the paste.
An arrangement for applying a fluid to a surface, comprising a hollow needle via which, in operation, the pressurised fluid is applied to the surface, is characterised in that the arrangement comprises a vibration device arranged to be coupled to the needle so as to make the needle vibrate longitudinally.
Preferably, the vibration device comprises a piezoelectric transducer connected to the needle. This enables the needle to be set into vibration in a constructionally simple manner. Obviously, other vibration devices are possible, such as electromagnetic or mechanical transducers.
The invention will now be described in more detail with reference to exemplary embodiments shown in the drawings. In the drawings:
  • Fig. 1 shows an arrangement for applying solder paste to a surface of a printed circuit board,
  • Fig. 2 represents diagrammatically the movement of the needle when this needle vibrates with a low frequency and the piezoelectric transducer is modulated with a sawtooth voltage,
  • Fig. 3 shows another arrangement for applying solder paste to a surface of a printed circuit board.
    • The arrangement with which the method is carried out comprises a container 1 having an outlet 2. The vibration device 3 has a housing 4, which accommodates a piezoelectric transducer 5. This transducer comprises a flat disc whose edge is clamped between housing portions 6. A hollow needle 7 extends through the centre of the disc and perpendicularly to the disc. The needle is fixedly connected to the disc. The housing 4 has a connecting sleeve 8 by which the housing can be secured to the outlet 2 of the container 1, for example by screw-thread means. When the housing is disposed on the container the hollow needle extends through the outlet 2 into the container. A sealing ring 9 is interposed between the housing and the hollow needle. A tube 10 connects the container to a pressure generator 11.
    The arrangement operates as follows:
    Under the influence of pressure the solder paste 12 in the container is forced through the hollow needle 7 and is applied to a surface 13 of a printed circuit board 14. The pressure is generally applied in a pulsating fashion. During the application of the paste the piezoelectric transducer 5 is set into vibration by a voltage, causing the hollow needle 7 to vibrate in its longitudinal direction.
    If the needle vibrates with a comparatively low frequency (1 - 100 Hz), the voltage can be modulated in such a manner that the needle moves slowly towards the surface and returns rapidly. This can be achieved by means of a sawtooth voltage. In this way the paste is subjected to a pumping action which facilitates the application of the paste. This is illustrated diagrammatically by means of Fig. 2. If the needle vibrates with a comparatively high frequency (1 - 30 kHz) the solder paste in the needle cannot follow the rapid movements of the needle. Satisfactory results are also obtained with a frequency of 6 - 7 kHz, a pressure on the paste of 0.5 bar, and a needle diameter of 0.2 mm. The paste output is approximately 40 % higher than when the needle is not vibrated. For a further improvement of the pumping effect a needle vibrating at high frequency may be combined with a sawtooth vibration as described above.
    Fig. 3 shows another vibration device. In this Figure like parts bear the same reference numerals as in Fig. 1. In the present embodiment the needle 7 is subjected to a low-frequency longitudinal vibration by means of a cam mechanism 15. An arm 16 is pivotally connected to the housing 4 of the vibration device 3. The needle 7 has a pin 17 engaging an opening 18 in the arm. The arm 16 extends transversely of the needle 7. A rotating cam 19 sets the arm 16 and hence the needle 7 into longitudinal vibration. A spring 20 urges the arm 16 against the cam surface 21 of the cam. The cam surface can be chosen in such a manner that the needle movement away from the surface of a printed circuit board is faster the needle movement towards this surface, which again produces said pumping action.
    The pressure generator is preferably a fluid pump, for example an axial flow pump, because such a pump produces a well-defined pressure. However, an air-pressure pump is also possible. The pump may directly form part of the arrangement or may be external to this arrangement and be connected to the container via flexible tubes. The container may also be external and may be connected to the needle via a flexible tube. This reduces the overall mass of the moving system, enabling the speed to be increased.

    Claims (10)

    1. A method of applying a fluid (12) to a surface (13), the method comprising pressurised fluid being applied from a container (1) to the surface through a hollow needle (7), characterised in that the needle is subjected to a longitudinal vibration during the application of fluid.
    2. A method as claimed in Claim 1, characterised in that the needle (7) is subjected to a vibration having a frequency between 1 and 100 Hz and the duration of the needle movement towards the surface (13) is longer than the duration of the needle movement away from the surface.
    3. A method as claimed in Claim 2, in which the fluid (12) is a solder paste, characterised in that the amplitude of the vibration is of the same order of magnitude as the grain size of the solder globules in the paste.
    4. A method as claimed in Claim 1, characterised in that the needle (7) is subjected to a vibration having a frequency between 1 and 30 kHz.
    5. A method as claimed in Claim 1, characterised in that the fluid (12) is subjected to a pulsating pressure concurrently with the needle (7) vibration.
    6. An arrangement for applying a fluid (12) to a surface (13), comprising a hollow needle (7) via which, in operation, the pressurised fluid is applied to the surface, characterised in that the arrangement comprises a vibration device (3) arranged to be coupled to the needle so as to make the needle vibrate longitudinally.
    7. An arrangement as claimed in Claim 6, characterised in that the vibration device (3) comprises a piezoelectric transducer (5) connected to the needle.
    8. An arrangement as claimed in Claim 7, characterised in that the piezoelectric transducer (5) is driven by a voltage having a frequency between 1 and 100 Hz, the amplitude of the voltage varying between two extreme values, the duration between the low value and the high value differing from the duration between the high value and low value.
    9. An arrangement as claimed in Claim 6, characterised in that the vibration device (3) comprises a cam mechanism (19).
    10. An arrangement as claimed in any one of the Claims 6 to 9, characterised in that pressure means (11) are provided for pressurising the fluid in the container.
    EP95921103A 1995-06-27 1995-06-27 Method of and arrangement for applying a fluid to a surface Expired - Lifetime EP0784514B1 (en)

    Applications Claiming Priority (1)

    Application Number Priority Date Filing Date Title
    PCT/IB1995/000521 WO1997001393A1 (en) 1995-06-27 1995-06-27 Method of and arrangement for applying a fluid to a surface

    Publications (2)

    Publication Number Publication Date
    EP0784514A1 EP0784514A1 (en) 1997-07-23
    EP0784514B1 true EP0784514B1 (en) 2001-10-10

    Family

    ID=11004344

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP95921103A Expired - Lifetime EP0784514B1 (en) 1995-06-27 1995-06-27 Method of and arrangement for applying a fluid to a surface

    Country Status (4)

    Country Link
    EP (1) EP0784514B1 (en)
    JP (1) JPH10505280A (en)
    DE (1) DE69523164T2 (en)
    WO (1) WO1997001393A1 (en)

    Families Citing this family (6)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE19913076A1 (en) 1999-03-23 2000-10-19 Hahn Schickard Ges Device and method for applying microdroplets to a substrate
    JP2000288452A (en) * 1999-04-02 2000-10-17 Matsushita Electric Ind Co Ltd Paste applying device and paste applying method
    DE29910780U1 (en) * 1999-06-21 1999-09-16 Hahn Schickard Ges Holding and actuating device
    DE10013451B4 (en) * 2000-03-17 2006-05-04 Degussa Ag Device for producing monodisperse drops
    DE10359112A1 (en) * 2003-12-17 2005-07-21 Voith Paper Patent Gmbh System to clean a curtain coater jet, to apply a liquid coating to a moving wet/dry web, uses pulses at a higher pressure level on the coating medium at regular intervals
    DK1833145T3 (en) 2006-03-10 2012-08-13 Kienle & Spiess Gmbh Method, tool and apparatus for producing slat packages and a slat package

    Family Cites Families (4)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    SE422970B (en) * 1975-12-15 1982-04-05 Odelius Kjell Erik DEVICE FOR REMOVAL OF COATINGS FOR FUEL ENGINES DEDUCED FUEL INJECTION VALVES
    ATE25598T1 (en) * 1983-07-06 1987-03-15 Lonza Ag PROCESS AND DEVICE FOR THE FINEST SPRAYING OF SUSPENSIONS.
    DE3728054A1 (en) * 1987-08-20 1989-03-02 Klatt Helmuth METHOD AND DEVICE FOR DOSING AND APPLYING LIQUID OR PASTOUS MEDIA TO AN OBJECT
    US5044555A (en) * 1990-07-23 1991-09-03 Herrmidifier Company, Inc. Self-cleaning solenoid controlled water spray nozzle and valve assembly

    Also Published As

    Publication number Publication date
    WO1997001393A1 (en) 1997-01-16
    DE69523164T2 (en) 2002-06-06
    JPH10505280A (en) 1998-05-26
    EP0784514A1 (en) 1997-07-23
    DE69523164D1 (en) 2001-11-15

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