Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/03—Observing, e.g. monitoring, the workpiece
  • B23K26/034—Observing the temperature of the workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K1/00—Soldering, e.g. brazing, or unsoldering
  • B23K1/005—Soldering by means of radiant energy
  • B23K1/0056—Soldering by means of radiant energy soldering by means of beams, e.g. lasers, E.B.
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/10—Devices involving relative movement between laser beam and workpiece using a fixed support, i.e. involving moving the laser beam
• • 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
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
  • H05K3/341—Surface mounted components
  • H05K3/3421—Leaded components
• • 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
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
  • H05K3/3494—Heating methods for reflowing of solder

Definitions

• the present invention relates to a method and a device intended for heating a deposited soldering material for the soldering or desoldering of parts, and more particularly intended for soldering and desoldering of electronic components mounted on the surface on a substrate such as 'an electronic card.
• soldering and desoldering of electronic components operated locally on a card are traditionally carried out either by thermal conduction using a conventional or CURIE effect soldering iron or using hot bars or by thermal conduction by blowing of hot air drawn through nozzles adapted to the shape of the component.
• thermal conduction using a conventional or CURIE effect soldering iron or using hot bars
• thermal conduction by blowing of hot air drawn through nozzles adapted to the shape of the component.
• Patent DE-A-2360308 describes and shows a method and a device for welding using a laser beam which is surrounded by a light beam, the laser beam passing through an orifice provided in a mirror deflecting the Ray of light.
• This method and this device are suitable for carrying out point-to-point welding, causing inhomogeneity of the weld points and consequently mechanical stresses.
• they could only be used to perform desoldering by carrying out an additional point-to-point suction operation of the welding material.
• the object of the present invention is in particular to remedy these drawbacks and provides a method and a device intended for heating a welding material deposited on at least one connection zone of at least two parts, for the purpose of welding or desoldering. of these.
• the method consists in emitting on the one hand a heating beam and on the other hand a locating light beam, in bringing one of these beams in coincidence with the other of such so that they reach the area to be heated by following the same route.
• the method consists, by deflecting this path so that these beams carry out a scan in coincidence, to proceed by scanning to locate the zone to be heated using the light beam of location and to proceed by this heating scan of this identified area using the heating beam, thus allowing the welding or desoldering of said parts.
• the method when the zone to be heated is subdivided into several spaced parts, the method can advantageously consist in emitting the above-mentioned beams so that the latter successively and mainly reach these spaced parts to be heated.
• the tracking light beam can advantageously be switched off during the heating operation of the area to be heated using the heating beam.
• provision may be made to measure the temperature of the solder material and of the two parts, preferably in the vicinity of the zone to be heated, and to regulate the heating beam as a function of at least one of these temperatures.
• the heating device comprises means for emitting a heating beam, means for emitting a locating light beam, means to bring the light beam and the heating beam into coincidence so that the heating beam and the locating light beam reach the area to be heated by following the same route, and means for deflecting this route so that the heating beam and the locating light beam scan coincidentally the area to be heated.
• the heating beam is preferably formed by a laser beam obtained from a CO2 source and the locating light beam is preferably constituted by an infrared beam, the means for bringing these beams into coincidence being constituted preferably with a dichroic blade.
• said scanning means deflecting the aforementioned path ' are preferably at high frequency and constituted by two reflectors with controlled pivoting, mounted on two coaxial shafts driven by galvonometric motors.
• means can advantageously be provided for measuring the temperature of the welding material and of the two parts, these temperature measurement means being connected to means for regulating the means for emitting the heating beam in order to regulate the power of the latter as a function of at least one of these temperatures.
• the present invention will be better understood from the study of a device for heating a welding material connecting or intended to connect two parts, one of which is an electronic component and the other of which is a substrate of the electronic card type, described by way of nonlimiting example and illustrated "by the single appended figure.
• the heating device shown in the single figure and generally identified by the reference 1 is intended for heating the various spaced solder points 2 connecting at least some of the tabs of an electronic component 3 to a connection circuit made at the surface of an electronic card 4.
• the component 3 comprises two series of five tabs which are provided on two opposite lateral sides, the welding points 2 being formed on two rectangular zones 5 and 6.
• the electronic card 4 is arranged horizontally and held on a table 7 adjustable horizontally in the directions X and Y and angularly by suitable means.
• the heating device 1 comprises a generator 8 generating a laser beam 9 obtained from a CO2 source, directed downwards. This generator 8 is supplied with electrical energy by an appropriate electrical circuit 10 'and is preferably cooled.
• the heating device 1 also comprises a generator 11 horizontally emitting an infrared light beam 12 which meets the laser beam 9.
• the heating device 1 comprises a dichroic blade 13 placed at 45 ° and which allows the infrared beam 12 to be deflected downwards so that the latter and the laser beam 9 , which crosses the dichroic blade 4, are in coincidence and therefore follow, from the dichroic blade 13 and downwards, the same course 14.
• the heating device 1 further comprises a scanning system marked generally by the reference 15 which makes it possible to deflect the path 14 so that the laser beam 9 and the infrared beam 12 reach from above and scan, at high frequency, the solder points 2 to be heated in zones 5 and 6.
• the scanning system 15 comprises a first deflector 16 which deviates horizontally the path 14 coming from the dichroic blade 13 towards a second deflector 17, the latter deflecting the path 14 downwards towards the table 7.
• the deflectors 16 and 17 are respectively mounted on coaxial and opposite shafts 18 and 19 driven by galvanometric motors 20 and 21 which are controlled by a control circuit 22 connected to an adjustment circuit 23 so that the deflectors 16 and 17 perform controlled pivoting movements.
• the generator 8 of the laser beam 9 being stopped, the operator starts the generator 11 which emits the infrared beam 12. It starts the scanning system 15.
• the adjustment circuit 23 of this scanning system 15 By means of the adjustment circuit 23 of this scanning system 15 and by moving the table 7 horizontally, the operator ensures that the zones 5 and 6 scanned by the infrared beam 12 and that the latter mainly reaches the points of solder 2 to be heated.
• the operator introduces into the adjustment circuit 23 the dimensional characteristics of the electronic component 3 and the references of the legs of the latter provided with solder points 2.
• the control circuit 22 controlling the motors 20 and 21 of so that the infrared beam 12 scans these points successively and cyclically, the operator then moves the table 7 horizontally so as to bring the light points in coincidence with the solder points 2 to be heated.
• the scanning system 15 and the table 7 being suitably adjusted and positioned, the operator stops the generator 11 of the infrared beam 12 and starts the generator 8 of the laser beam 9 which heats successively and cyclically to gradually reach the desired temperature homogeneously on all the points, in a single operation, the different points 2 of the zones 5 and 6.
• the control circuit 22 regulates the electric circuit 10 so that, preferably, the laser beam does not be emitted only to the welding points 2 to be heated.
• the laser beam 9 scans the points 2 of the zones 5 and 6 in coincidence with the light points which the infrared beam 12 scanned.
• the operator stops the generator 8 of the laser beam 9 and can then stop the scanning system 15, these stops being able to be caused automatically after a predetermined time.
• the welding operation is, in one operation, complete.
• the operator can remove this component 3 for example using a suction nozzle.
• the heating device 1 comprises a measurement circuit 24, formed for example by an optical pyrometer equipped with a reflex sight, making it possible to measure for example the temperature of the welding material 2, the temperature of the component 3 and the temperature of card 4, in the vicinity of zones 5 and 6.
• a measurement circuit 24 formed for example by an optical pyrometer equipped with a reflex sight, making it possible to measure for example the temperature of the welding material 2, the temperature of the component 3 and the temperature of card 4, in the vicinity of zones 5 and 6.
• the measurement circuit 24 is connected to a regulation circuit 25.
• This regulation circuit 25 is connected to the control circuit 10 of the generator 8 of the laser beam 9.
• the regulation circuit 25 makes it possible to regulate the supply circuit 10 in order to regulate the power of the laser beam 9 as a function of at least one of the abovementioned temperatures so that, for example, at least one of these temperatures remains below a prefixed maximum value. This provision is provided to avoid overheating of component 3 or of card 4.
• a heating device 1 may be used in which the scanning system 15 is placed approximately 400 mm above the board 4 and whose laser and light beams 9 and 12 would have a diameter greater than 1mm, for example 1.5mm.
• the control circuit 11 would be programmed so that the beams 9 and 12 successively and at high frequency reach the different welding points 2 of the zones 5 and 6, without transmitting between these points or by transmitting with a clearly weakened power.
• the heating time can then be approximately five seconds.

Landscapes

• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Plasma & Fusion (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Laser Beam Processing (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9395112

Family Applications (1)

Country Status (2)

Cited By (5)

Citations (3)

• 1990
  • 1990-03-26 FR FR9003833A patent/FR2659886A1/fr active Granted
• 1991
  • 1991-03-25 WO PCT/FR1991/000237 patent/WO1991014529A1/fr unknown

Patent Citations (3)

Non-Patent Citations (1)

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