Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING 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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
  • C23G5/02—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S134/00—Cleaning and liquid contact with solids
  • Y10S134/902—Semiconductor wafer

Definitions

• the present invention relates to a
• the oldest known method consists in free or forced evaporation of water in the atmosphere, which as major drawbacks, the formation of stains and the oxidation of surfaces, which are generally inadmissible. More modern methods are based on the use of water repellent liquids to remove water from surfaces. Other methods use baths such as tri chl orethylene or perchl orethylene boiling with added surfactants. The water is thus eliminated by the formation of azeotropes, and there is little or no oxidation of the surfaces, but the problem of stains is not resolved however.
• patent CH 499.075 recommends the use of fluorinated solvents and surfactants which are not capable of forming an azeotropic mixture with water.
• US patent 4,169,807 it describes as a means of drying silicone-based parts mixtures containing propanol, water and certain perfluorinated compounds.
• the object of this invention is to overcome the drawbacks of known methods for rinsing surfaces, by providing a process which does not require the use of water or surfactants.
• the process according to the invention aiming to achieve the above object, is characterized in that the surfaces are treated with a non-solvent liquid, thermally stable and chemically inert, so as to form an emulsion with the aqueous liquid present on said surfaces, until complete elimination thereof.
• the surfaces can then be subjected to additional rinsing in the presence of vapors of said non-solvent liquid and then to drying.
• Another object of this invention consists of an installation for implementing the method according to the invention.
• This installation is characterized by the fact that it includes a first rinsing zone in which are arranged means for treating the surfaces with an inert non-solvent liquid intended to form an emulsion with the aqueous liquid to be removed present on said surfaces.
• This installation may also include means for vaporizing said inert non-solvent liquid in a second rinsing zone, and a drying zone preferably situated directly above this second rinsing zone in the vapor phase.
• the installation may also further comprise means for recovering the emulsion formed and means for breaking said emulsion, means for separating the two liquid phases formed, as well as separate circuits for recycling the liquids thus separated.
• a container containing the LFI can be used and in which the parts are immersed. These can be placed in bulk in baskets or drums, mounted on racks provided for this purpose, or suspended in the case of larger pieces, or else maintained in the LFI by any type of support, or in the case of a continuous technique in the form of a passage in strip, wire, film, etc.
• the emulsion is preferably obtained by application of ultrasound, for example at frequencies generally between 20 and 80 kHz, or by more or less energetic agitation and vibration of the parts to be treated immersed either transmitted mechanically by an external source, or induced electro-internally inside the parts , or by agitation and vibration of the container itself and transmission to the parts submerged by the liquid.
• ultrasound for example at frequencies generally between 20 and 80 kHz, or by more or less energetic agitation and vibration of the parts to be treated immersed either transmitted mechanically by an external source, or induced electro-internally inside the parts , or by agitation and vibration of the container itself and transmission to the parts submerged by the liquid.
• spraying and spraying techniques can be used at higher or lower pressures.
• the inert non-solvent liquid used in the process according to the invention is preferably a completely fluorinated organic compound of the "Fluorinert” type (of 3).
• These compounds derived from common organic compounds by replacing all the hydrogen atoms with fluorine atoms, therefore contain neither hydrogen nor chlorine. They are non-polarized and have practically no solvent action. They are colorless, odorless, slightly toxic and non-flammable, but above all have high thermal stability and are chemically inert.
• These LFI compounds are therefore as regards their properties completely different from the solvents chl orof1 uor ⁇ s usually used as solvents, degreasing and drying agents,
• the exceptional chemical inertness of LFIs means that they do not contaminate or. in no way modify the aqueous solutions that they emulsify, and that these can therefore be reused directly upstream of the
• Some stable fluorosurfactants can dissolve to some extent in LFIs. Therefore, and although it is not generally necessary, it may be in
• the use of the emulsion technique if applied with a non-solvent liquid makes it possible to envisage applying the method according to the invention not only to non-absorbent surfaces, but also to bodies such as unvarnished ceramics. , frits, woven fabrics, etc.
• This process can therefore be implemented not only for example in the technical fields of electroplating, the manufacture of silicon wafers, printed circuits, etc., but also in photolithography, in the manufacture and development of photographic films, the treatment and in particular the dyeing of textiles, the leather industry, the chemical industry, that of mines, etc.
• the parts to be rinsed (not shown) are introduced directly into a tank or container 1 containing cold LFI 2 (room temperature).
• Ultrasonic transducers 3 are activated to allow 1 e ul if onion of the liquid to be eliminated by the LFI.
• This emulsion is subjected to an upward movement, because its density is less than that of the LFI on the one hand, and on the other hand because the LFI is introduced into the tank 1 from the bottom, by means of a pump. recirculation 4 and via an intermediate filter 5.
• the emulsion 6 therefore overflows from the tank 1 and is directed towards a high-voltage demulsifier 7.
• This demulsifier 7 comprises an axial filiform electrode 8 connected to a high-voltage source and a conductive cylindrical body connected to the ground.
• the emulsion is then broken by the union of the micro-droplets in large drops.
• the mixture LFI / large drops 9 of liquid to be eliminated then passes through a decanter 10 or Florentine vase.
• the aqueous liquid to be eliminated less dense than the LFI, floats on the surface of the latter and, by successive additions, overflows through the discharge pipe 11; this aqueous liquid is recovered and can be reused directly as such upstream of the manufacturing process.
• the LFI it passes under the baffle 10 'and overflows into the tank 12 of the settling tank 10, this part of the tank serving as a container for balancing variations in levels of the entire installation.
• the pump 4 draws off the dry and clean LFI from the tank 12, which then passes through a filter 5 and enters the tank 1 through the bottom and through anti-turbulence shutters 13, pushing thus the emulsion upwards, like a pis ⁇ ton, in order to quickly replace the emulsion with dry and clean LFI.
• a turbidity detection device 14 determines the end of the emulsification process, that is to say as soon as the LFI is perfectly clear and without cloudiness, which means that the surfaces to be rinsed are then completely rid of the liqui ⁇ de aqueous to be removed.
• Another possibility of checking consists in inserting a voltage detector and / or a current detector in the high-voltage supply circuit of the demulsifier, the voltage being inversely proportional and the current being proportional to the quantity of the microdroplets arriving in the demulsifier.
• the parts are then removed from the first rinsing zone in the liquid phase (tank 1) and they pass into a second rinsing zone 15 in the vapor phase containing the vapors of the LFI liquid.
• These vapors are produced by two boilers 16 heated by heating bodies 17 and supplied with LFI by the tank 12.
• a level detection system 18 controls the valves 19.
• the parts In the vapor zone 15, they condense on the parts which are extracted from the cold LFI of the tank 1, which has the consequence that the liquid thus distilled, extremely pure, eliminates by entrainment any impurities which may be present. still on the surfaces, and that the thermal energy of the vapors is transferred to the parts, which therefore heat up.
• the parts can then be removed from the vapor zone 15 to enter the drying zone 20, the walls of which are cooled by a double jacket 21, in which a cooling fluid (water, "Freon", etc.).
• the cooling of the walls can also be ensured by a coil in which a cooling fluid circulates.
• the LFI present on the parts heated by the latter evaporates and recondenses on the cold walls of the double-coat.
• the recondensed LFI flows along the walls and is brought into a settling tank (Florentine vase) 22, together with a small amount of water from the humidity of the ambient air and also condensed on the walls of the double -coat, water floating on. the denser surface of the LFI and, by successive additions, overflows by a pipe 23 to be evacuated to the sewer.
• the LFI thus distilled, is reintroduced by gravity into the bottom of the tank 1.
• the impurities brought to the system are collected either in the filter 5 or at the bottom of the boilers 16.
• a non-return valve 24 has been provided to prevent the LFI of the tank 1 from being emptied by gravity into the tank 12.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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• 1985
  • 1985-09-13 CH CH3984/85A patent/CH663554A5/fr not_active IP Right Cessation
• 1986
  • 1986-09-11 DE DE8686905186T patent/DE3675540D1/de not_active Expired - Lifetime
  • 1986-09-11 EP EP86905186A patent/EP0238517B1/de not_active Expired - Lifetime
  • 1986-09-11 JP JP61504668A patent/JPS63501348A/ja active Pending
  • 1986-09-11 WO PCT/CH1986/000130 patent/WO1987001740A1/fr active IP Right Grant
• 1988
  • 1988-07-22 US US07/223,679 patent/US4936921A/en not_active Expired - Fee Related
• 1990
  • 1990-02-02 US US07/473,873 patent/US5004000A/en not_active Expired - Fee Related

Non-Patent Citations (1)

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