Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/22—Secondary treatment of printed circuits
  • H05K3/26—Cleaning or polishing of the conductive pattern
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/02—Cleaning by the force of jets or sprays
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/22—Secondary treatment of printed circuits
  • H05K3/227—Drying of printed circuits
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
  • H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
  • H05K2201/10621—Components characterised by their electrical contacts
  • H05K2201/10689—Leaded Integrated Circuit [IC] package, e.g. dual-in-line [DIL]
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/07—Treatments involving liquids, e.g. plating, rinsing
  • H05K2203/0736—Methods for applying liquids, e.g. spraying
  • H05K2203/0746—Local treatment using a fluid jet, e.g. for removing or cleaning material; Providing mechanical pressure using a fluid jet
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/08—Treatments involving gases
  • H05K2203/081—Blowing of gas, e.g. for cooling or for providing heat during solder reflowing
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/15—Position of the PCB during processing
  • H05K2203/1509—Horizontally held PCB

Definitions

• the present invention relates to the manufacture of electronic circuits, in particular as regards their cleaning before use for mounting various devices.
• an electronic circuit includes a rigid insulating card on which the layout of the circuit itself is printed. On the studs or perforations of this card, the metal tabs of the various components, electronic components, or integrated circuits are fixed, using a welding flux.
• Printed circuits are generally washed, then dried during their manufacture or after assembly, in order to eliminate from their surface chemical materials or contaminants, such as solder flux, not compatible with their end use, and liable to '' alter their performance and reliability.
• the object of the present invention is to avoid these drawbacks, by cleaning the electronic circuits by a new process capable of effectively removing impurities, including those which are trapped under the components, between them and the printed circuit board that supports them.
• the method according to the invention for cleaning an electronic circuit which comprises components welded by their tongues to the rigid card of a printed circuit, is characterized in that it consists in placing the card of the electronic cooked circuit in front of a thin liquid curtain, projected by an injector in a direction substantially perpendicular to the plane of the card in the impact zone where the liquid curtain strikes it.
• a relative displacement is created between the card and the water which strikes it, this relative displacement being substantially parallel to the plane of the card in the zone of impact of the liquid. .
• This relative displacement can be obtained:
• the surface of the electronic circuit is swept by the curtain of water which strikes it.
• the curtain of pressurized water firstly provides significant mechanical action along its line of impact, which produces detachment of any impurities in this area.
• the curtain of water separates into two very thin liquid layers, which flow at high speed in opposite directions over the surface to be washed, which is thus subjected in its ⁇ tality, dynamic washing action, including in the areas under the components, and therefore inaccessible to a direct jet.
• These thin liquid layers can slip into spaces of a few tens of microns only, and in particular eject the impurities trapped in the interstices and defined between the upper face of the card and the lower face of the components which it carries.
• Figure 1 is a perspective view showing a device according to the invention, during operation.
• Figure 2 is a section along II - II
• FIG. 3 is a similar section illustrating an additional phase where, after washing with a curtain of water, a drying operation is carried out, by spraying a gaseous curtain, formed for example by air,
• FIG. 4 shows a variant of FIG. 2.
• the device illustrated in FIGS. 1 and 2 comprises a fixed injector 1, of a type known per se, supplied with a liquid such as water, to project downwards a thin curtain of rectilinear water 2.
• the thickness 3 of the water curtain 2 is preferably very small, for example of the order of 60 to 150 microns.
• the water being projected under high pressure it flows into the curtain 2, with a speed preferably greater than 20 meters per second.
• a support table 4 on which it is circulated ' , parallel to themselves, following the direction of the arrows 5, electronic circuits of the kind indicated on the drawings by the global reference 6.
• Each electronic circuit 6 comprises various components, such as 7, 8, 9, etc.
• each component such as 7, 8, 9, includes languaget ⁇ your metal 11, which is welded to the card 10 of the printed circuit.
• each jet such as the water curtain 2
• provides in the first place, an important action such as the water curtain 2, provides in the first place, an important action leverca ⁇ nic on its impact line 13, when 1 is projected on the solid surface of the card 10. It then generates two
• ⁇ _D jet 1 (or a similar injector 18; FIG. 3), with air, to project, this time, a gaseous curtain 19. Thanks to the high kinetic energy of the jet formed by this gaseous curtain 19, the residual liquids 20 (coming from the curtain 3Q preceding liquid 2) are discharged outside the surface to be dried, so that there remains on the card 10, only a minimum quantity of liquid, which will evaporate later. in the case where the liquid curtain 2 is constituted by a volatile and expensive liquid, such as the
• the invention provides for reducing consumption as illustrated in the variant of FIG. 4.
• 1 assembly of FIG. 2 is capped with a sealed tunnel 21 whose inlet and outlet are surmounted by a transverse injector
• the products or circuits 6 easily pass through the air curtains 24 and 25, while these confine the FREON vapors emitted by the washing curtain 2. It can be seen that this considerably reduces the consumption of FREON necessary for the 'supply of 1' washing injector 1.
• 24 and 25 can also be water curtains.
• the washing jets 2 are oriented longitudinally, that is to say parallel to the direction of advance 5 of the cards 10 and of the conveyor 26 which carries them.
• the projections 16 and 17 of the polluted liquid which splash out are directed laterally, towards the outside. This guarantees that the polluted fluid 16, 17 of a cleaning station 27 does not pollute the rooms of a neighboring station 28 and vice versa (phenomenon known as "cross-contamination"). This also reduces the size of the machine.
• each jet 2, 19 . 25 can be fixed or driven by an alternating scanning movement (double arrow 33), in which case the jet is said to be "scanning jet”.
• a complementary technique of implementing fluid curtains with high kinetic energy in order to improve the quality of washing and drying of printed circuits comprising conventional components such as resistance, capacity, integrated circuit , LSI (large scale integration), VLSI (very large scale integration) etc ... or components such as semi-standard integrated circuits, integrated circuits with specific application with programmable logic (PAL), on demand (full custom ) or semi-specific precharacterized (standard cells) and prediffused (spoiling arrays), surface mounted or not.
• PAL programmable logic
• PAL programmable logic
• on demand full custom
• semi-specific precharacterized standard cells
• prediffused spoiling arrays
• the jet must be of the curtain type with a length of a few tens of millimeters (from 20 to 500 mm approximately).
• the thickness of the incident jet is preferably between 60 and 150 microns with liquids, from 40 microns with gases of different thicknesses may be required.
• the jet impact line is parallel to the conveyor running axis (ADC).
• the jet is moved back and forth (scanning) so as to sweep the surface to be washed.
• the scanning frequency is determined as a function of the length of the jet and the speed of travel of the circuits, from one cycle per second to one cycle per 10 seconds approximately. The device allowing the back and forth or sweep
• scanning of the nozzle or of the jet deflector may be of mechanical, electro-mechanical, mechanical-hydraulic or other type. It allows in particular the adjustment of the scanning frequency and amplitude, the jet being kept constantly orthogonal to the printed circuit while the jet impact line remains constantly parallel to the ADC.
• the fluids used can be: liquids (water, mixture of water and saponifying products, freon-type solvents, azeotropic mixtures of freon and alcohols, chloro-fluorinated solvents, chlorinated solvents, alcohols, etc.) or gaseous ( air, solvent vapors, etc.).

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing Of Printed Wiring (AREA)
• Cleaning By Liquid Or Steam (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26224756

Family Applications (1)

Country Status (2)

Families Citing this family (2)

Family Cites Families (2)

• 1986
  • 1986-09-29 WO PCT/FR1986/000334 patent/WO1987002213A1/fr not_active Application Discontinuation
  • 1986-09-29 EP EP19860905850 patent/EP0240528A1/de not_active Withdrawn

Non-Patent Citations (1)

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