EP0176862B1 - Appareil pour revêtement électrostatique - Google Patents

Appareil pour revêtement électrostatique Download PDF

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Publication number
EP0176862B1
EP0176862B1 EP85111763A EP85111763A EP0176862B1 EP 0176862 B1 EP0176862 B1 EP 0176862B1 EP 85111763 A EP85111763 A EP 85111763A EP 85111763 A EP85111763 A EP 85111763A EP 0176862 B1 EP0176862 B1 EP 0176862B1
Authority
EP
European Patent Office
Prior art keywords
movement
workpieces
electrostatic spraying
spraying device
electrostatic
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
Application number
EP85111763A
Other languages
German (de)
English (en)
Other versions
EP0176862A1 (fr
Inventor
Hilmar Dipl.-Ing. Reichel
Hans Raske
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Priority to AT85111763T priority Critical patent/ATE38947T1/de
Publication of EP0176862A1 publication Critical patent/EP0176862A1/fr
Application granted granted Critical
Publication of EP0176862B1 publication Critical patent/EP0176862B1/fr
Expired 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
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/082—Plant for applying liquids or other fluent materials to objects characterised by means for supporting, holding or conveying the objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B13/00—Machines or plants for applying liquids or other fluent materials to surfaces of objects or other work by spraying, not covered by groups B05B1/00 - B05B11/00
    • B05B13/02—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work
    • B05B13/0221—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work characterised by the means for moving or conveying the objects or other work, e.g. conveyor belts
    • B05B13/0235—Means for supporting work; Arrangement or mounting of spray heads; Adaptation or arrangement of means for feeding work characterised by the means for moving or conveying the objects or other work, e.g. conveyor belts the movement of the objects being a combination of rotation and linear displacement

Definitions

  • the invention relates to an electrostatic spray device according to the preamble of claim 1.
  • Such electrostatic spraying devices for paints are known, for example, from “Lueger Lexicon of Technology” Volume 9, L-Z, Deutsche Verlags-Anstalt Stuttgart, 1968, pp. 14 to 16.
  • lacquers the forces occurring in an electrostatic high-voltage field are used to transport the droplets of lacquer to the workpiece, the atomization of the lacquer being carried out mechanically or likewise by means of electrical forces.
  • the paint droplets in the high-voltage field are charged or ionized, i. H. they are moved along the lines of force of the field by electric field forces. This movement then ends on the workpiece surface, where the paint droplets discharge and cover the workpiece as a paint film.
  • a method is further described which makes it possible to electrostatically apply a film, which consists of a certain material, to the inner surface of a hollow body.
  • these are fluorescent powdery substances which, after application of a film of water, are applied to the inner surface of a lamp body to be coated under the action of an electrostatic field with the aid of translational and / or rotational movements.
  • the movements mentioned here are relative movements between an application device and the recipient, here the lamp body. In other words, the relative movements associated with their timing are necessary in order to obtain the desired film layer uniformly at all points of the recipient. Statements about the material yield and quality of the film layer are only made insofar as the quality of the raw material provided is varied.
  • liquids have to be applied to silicon wafers in such a way that a very thin and completely uniform, homogeneous film is formed over the entire surface.
  • These liquids which are, for example, masking, doping and anti-reflective lacquers, have previously been applied by centrifugal processes or by dipping.
  • these painting methods were unable to meet the requirements placed on the quality of the paint films in general and especially in solar technology.
  • the invention has for its object to provide a device for painting workpieces, in particular silicon wafers, which enables the production of extremely thin, completely uniform, pore and crack-free paint films.
  • the invention is based on the finding that extremely thin and completely uniform films can be produced when applying liquids by electrostatic spraying, provided the workpieces are subjected to a periodic translational and / or rotational movement in the form of a high-frequency vibration during the spraying process.
  • the liquid droplets that initially hit the workpiece surface unite very quickly due to the periodic movement of the workpiece and thus form a coherent, uniform film within a very short time.
  • closed and pore-free films can also be guaranteed with much smaller layer thicknesses than previously.
  • varnishing silicon wafers a varnish yield of over 90% is achieved, whereas only varnish yields of at most 30% have been achieved in the previously used centrifugal processes.
  • This high paint yield and the correspondingly low level of contamination of the electrostatic spraying device then made it possible to significantly increase the economy of the paint job.
  • the electrostatic spraying device according to the invention can advantageously be used wherever very thin and completely uniform, homogeneous films are to be produced on the surface of workpieces.
  • other areas of application include the application of adhesives, synthetic resins or lubricants.
  • a periodic translational movement in the application direction of the liquid can be impressed on the workpieces by the movement device.
  • Such a periodic translational movement aligned perpendicular to the workpiece surface has proven to be particularly favorable with regard to the acceleration of the film formation.
  • the workpieces are impressed with a periodic translational movement that is normal to the direction of application of the liquid.
  • a rotational movement can be impressed on the workpiece in order to accelerate the film formation by means of the movement device, the axis of rotation of which in the application direction of the liquid and centrally to the electrostatic high voltage field is aligned.
  • the movement device is then preferably designed as a piezoelectric oscillation device, with which ultrasonic vibrations can be generated in a relatively simple manner.
  • the movement device is then expediently coupled to a workpiece support via a vibration converter.
  • the vibration can then be amplified according to the respective requirements with the help of the vibration converter.
  • the vibration converter is attached to the underside of a horizontally oriented workpiece support.
  • This horizontal arrangement has a particularly favorable effect on the uniformity of the film, in particular in the case of workpieces with flat surfaces, since this favors the unification of the paint droplets but prevents uneven flow.
  • a plurality of inert gas jets can be directed onto the workpiece surface from an inert gas shower arranged at a distance from the workpiece surface. It is particularly economical if nitrogen can be supplied as an inert gas to the inert gas shower.
  • the inert gas shower reduces the risk of explosion in some liquids to be applied.
  • the inert gas shower prevents harmful effects of atmospheric oxygen on the liquid droplets and on the formation of the film on the workpiece surface.
  • the workpiece W which is a silicon wafer
  • a horizontally aligned workpiece support Wa is arranged on a horizontally aligned workpiece support Wa.
  • a purely schematically illustrated movement device B which has the task of imparting a periodic translation and / or rotation movement to the workpiece support Wa and thus to the workpiece W during the painting process.
  • the periodic translational movement can be an oscillation in the vertical direction or an oscillation in the horizontal direction, it also being possible to superimpose both forms of oscillation.
  • An arrow R indicates that the workpiece support Wa can also be rotated about a vertically aligned, central axis of rotation Ra during the painting process.
  • This rotational movement possibly superimposed on the translational movements Tv or Th, can be an oscillating rotary movement or a continuous rotation, but in the latter case one revolution per painting process should not be exceeded.
  • the anti-reflective lacquer which is accommodated in the form of a liquid F in a storage container V, is fed via a line L to an atomizing device Z, which produces a mist of fine liquid droplets.
  • a high-voltage generator H that can be set to different voltage values and has a maximum voltage of, for example, 100 kV is connected with its positive pole to the grounded workpiece support Wa and with its negative pole to the atomizing device Z and the storage container V. This creates an electrostatic high-voltage field between the atomizing device Z and the workpiece W electrically conductively connected to the workpiece support Wa, along the force lines K of which the negatively charged liquid droplets are specifically moved to the workpiece surface by the electrical field forces.
  • the liquid droplets discharge there and combine to form a coherent film. Due to the periodic movement impressed on the workpiece W with the aid of the movement device B, the unification of the liquid droplets and the homogenization of the layer are greatly promoted, so that the painting process can be ended quickly and a very thin and completely uniform film is formed over the entire surface.
  • FIG. 2 shows a first embodiment of an electrostatic paint spraying device, in which the movement device designated here B 'is designed as a piezoelectric oscillation device, which is coupled to the underside of the workpiece support Wa via a oscillation transducer Sw that serves to transmit and amplify oscillations.
  • the piezoelectric oscillation device is connected to an ultrasound generator US, which can be set to frequencies between 20 and 100 kHz and whose feed lines are connected to an electrode E of the piezoceramic and the oscillation converter Sw.
  • the piezoelectric oscillation device generates a high-frequency translation movement Tv acting in the vertical direction, which is transmitted to the workpiece W via the vibration transducer Sw designed as a solid aluminum part and the workpiece support Wa.
  • the liquid F supplied via the line L from the storage container V drips down through the upper opening widening funnel T and then reaches the top of a rotating and horizontally aligned disc S.
  • This disc S is driven by a magnetic coupling M and an air motor LM, which can be adjusted to a pressure of 20,000 to 70,000 rpm via a compressed air supply Pv with variable pressure can.
  • the liquid droplets hitting the rotating disc S are thrown against the inner wall of the funnel T, which is connected to the negative pole of the high-frequency generator H.
  • the liquid F then atomizes at the lower edge of the funnel T, since the electrical forces exceed the surface forces.
  • the amount of liquid supplied to the lower edge of the funnel T as a fine film breaks down into individual small liquid droplets which are ionized and migrate along the force lines K of the high-voltage field between the spray edge of the funnel T and the workpiece W.
  • the charge of the liquid droplets is very high, which leads to a degree of separation or a paint yield of well over 90%.
  • FIG. 2 also shows an inert gas shower ID arranged above the spray edge of the funnel T, from which a large number of inert gas jets IS are directed onto the workpiece surface.
  • This inert gas shower ID prevents on the one hand the risk of an explosion and on the other hand an oxidation of the finely atomized liquid droplets or of the film formed from these liquid droplets.
  • Nitrogen from a nitrogen supply Sv is supplied to the inert gas shower ID as the inert gas, the pressure of which is set to, for example, 4 bar.
  • FIG. 4 shows a second embodiment of an electrostatic paint spraying device, in which the movement device B 'already explained in connection with FIG. 2 is used again.
  • the atomizing device Z 'used in this second embodiment comprises an automatic spray gun Sp with an extended spray tube Sr with radial spraying action.
  • the spray gun Sp is supplied with the paint in the form of a liquid F via a first line and the spray air SI required for atomization via a second line.
  • compressed air PI is introduced into a tube Ro concentrically surrounding the spray tube Sr for additional regulation of the spray jet.
  • an inert gas in particular nitrogen, can also be introduced into the tube Ro, in order to produce effects similar to the inert gas shower ID shown in FIG.
  • a ring electrode Re arranged around the gun outlet is connected to the negative pole of the high-voltage generator H, so that an electrostatic high-voltage field is generated between this ring electrode Re and the workpiece W, the lines of force of which are again denoted by K.
  • the liquid droplets generated by the spray gun Sp are ionized by the corona effect on the lower edge of the ring electrode Re and reach the electrostatic high-voltage field as negatively charged floating particles, where they migrate along the lines of force K to the workpiece W, discharge there and a closed, form extremely thin and uniform homogeneous film.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Confectionery (AREA)
  • Catching Or Destruction (AREA)

Claims (9)

1. Dispositif de projection électrostatique pour déposer des liquides, notamment des vernis, à la surface des pièces, les fluides étant envoyés à un dispositif de pulvérisation et étant transportés dans un champ électrostatique haute tension sous forme de fines gouttelettes sur la surface de la pièce, caractérisé en ce que aux pièces (W) est associé un dispositif de mise en mouvement (B ; B') qui leur imprime un mouvement périodique de translation et/ou de rotation (Tv, Th, R) sous forme d'une oscillation haute fréquence.
2. Dispositif de projection électrostatique suivant la revendication 1, caractérisé en ce que un mouvement périodique de translation (Tv) dans la direction de dépôt du liquide (F) peut être imprimé aux pièces (W) par le dispositif de mise en mouvement (B ; B').
3. Dispositif de projection électrostatique suivant la revendication 1 ou 2, caractérisé en ce que un mouvement périodique de translation (Th) normal à la direction de dépôt du liquide (F) peut être imprimé aux pièces (W) par le dispositif de mise en mouvement (B).
4. Dispositif de projection électrostatique suivant l'une des revendications précédentes, caractérisé en ce que le dispositif de mise en mouvement (B) peut imprimer aux pièces (W) un mouvement de rotation (R), dont l'axe de rotation (Ra) est dirigé dans la direction de dépôt du liquide (F) et est centré par rapport au champ électrostatique en haute tension (Hsf).
5. Dispositif de projection électrostatique suivant la revendication 4, caractérisé en ce que le dispositif de mise en mouvement (B') est constitué en dispositif piézoélectrique oscillant.
6. Dispositif de projection électrostatique suivant la revendication 5, caractérisé en ce que le dispositif de mise en mouvement (B') est accouplé à un support de pièce (Wa) par un transducteur d'oscillations (Sw).
7. Dispositif de projection électrostatique suivant la revendication 6, caractérisé en ce que le transducteur d'oscillations (Sw) est monté sur le côté inférieur d'un support de pièce (Wa) dirigé horizontalement.
8. Dispositif de projection électrostatique suivant l'une des revendications précédentes, caractérisé en ce que un grand nombre de jets de gaz inerte (IS) peut être dirigé sur la surface de l'objet à partir d'une rampe de gaz inerte (ID) disposée à distance de la surface de l'objet.
9. Dispositif de projection électrostatique suivant la revendication 8, caractérisé en ce que de l'azote peut être envoyé à la rampe de gaz inerte (ID) en tant que gaz inerte.
EP85111763A 1984-09-20 1985-09-17 Appareil pour revêtement électrostatique Expired EP0176862B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85111763T ATE38947T1 (de) 1984-09-20 1985-09-17 Elektrostatische spritzeinrichtung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3434561 1984-09-20
DE3434561 1984-09-20

Publications (2)

Publication Number Publication Date
EP0176862A1 EP0176862A1 (fr) 1986-04-09
EP0176862B1 true EP0176862B1 (fr) 1988-11-30

Family

ID=6245904

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85111763A Expired EP0176862B1 (fr) 1984-09-20 1985-09-17 Appareil pour revêtement électrostatique

Country Status (3)

Country Link
EP (1) EP0176862B1 (fr)
AT (1) ATE38947T1 (fr)
DE (1) DE3566507D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3919653A1 (de) * 1989-06-16 1990-12-20 Alfo Ag Elektrostatische spritzpistole

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8715035D0 (en) * 1987-06-26 1987-08-05 Sansome D H Spray depositing of metals

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1272250A (fr) * 1960-10-25 1961-09-22 Gen Electric Co Ltd Procédé de formation d'enduits internes sur des récipients creux
CH615356A5 (en) * 1976-04-07 1980-01-31 Kreuzig Franz Apparatus for uniform spraying of thin-layer plates with reagents for quantitative thin-layer chromatography
US4197000A (en) * 1978-05-23 1980-04-08 Fsi Corporation Positive developing method and apparatus
DE3122204C2 (de) * 1981-06-04 1983-03-03 Erich 8000 München Ortmeier Verfahren zum elektrostatischen Auftragen von pulverförmigen Stoffen auf Werkstücken und Beschichtungskabine zur Durchführung des Verfahrens

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3919653A1 (de) * 1989-06-16 1990-12-20 Alfo Ag Elektrostatische spritzpistole

Also Published As

Publication number Publication date
ATE38947T1 (de) 1988-12-15
EP0176862A1 (fr) 1986-04-09
DE3566507D1 (en) 1989-01-05

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