Brazing apparatus

Details Brazing apparatus Brazing apparatus

1998-08-10

2000-04-18

Ryan, Patrick

Metal fusion bonding

Including means to apply flux or filler to work or applicator

By partial or total immersion of work or applicator into liquid

228260, 219603, 219615, B23K 108, B23K 1301, B23K 3512

Patent

active

060504730

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FILED

The present invention relates to a brazing apparatus using an electromagnetic induction pump.


BACKGOUND

FIG. 8 shows the general structure of a conventional wave soldering device, wherein a work conveyor 14 adapted to convey workpieces to be soldered, such as component-mounted substrates or the like, extends from a workpiece inlet 12 to a workpiece outlet 13 of a device cover 11.
A fluxer 15 for applying foamed flux to workpieces, a preheater 16 for preheating the workpieces, a solder bath 17 for soldering the workpieces by using molten solder ejected from wave nozzles, and a fan 18 for cooling the workpieces after soldering are arranged in this order along the conveyor 14.
A primary wave nozzle 21a and a secondary wave nozzle 21b are disposed in the solder bath 17. A wave-forming plate 22 has numerous ejection holes is provided at the open top of the primary wave nozzle 21a. The primary wave nozzle 21a is adapted to feed molten solder over the entire workpiece, covering every corner of the electrode portions and other parts of chip components by means of numerous small primary waves W1 which are ejected as irregular spouts from the ejection holes of the wave-forming plate 22. The secondary wave nozzle 21b is adapted to adjust the shapes of soldered parts by means of gentle secondary waves W2.
As shown in FIG. 9, the solder bath 17 is provided with a pressure duct 23 fitted in an opening at the bottom of the nozzle body 21 of the wave nozzles 21a,21b, and a pump impeller 24 disposed at the end of the pressure duct 23. The solder bath 17 also includes a suction opening 25 and a motor drive mechanism 26 associated with the pump impeller 24.
Molten solder introduced from the suction opening 25 as a result of rotation of the pump impeller 24 is fed under pressure through the pressure duct 23 into the nozzle body 21 and emitted from the nozzle body 21 in waves so that the undersides of workpieces P, which may be component-mounted substrates, are soldered while they are conveyed, being held between conveyor claws 27 of the conveyor 14. The major part of the solder waves directly returns onto the molten solder surface 28 in the solder bath 17 and is circulated into the suction opening 25 of the pump impeller 24.
Various brazing apparatuses using an electromagnetic pump are disclosed in, for example, Japanese Patent Publication Nos. 42590-1976, 31628-1990 and 60581-1991, and Japanese Utility Model Publication No. 17572-1988. Electromagnetic pumps used in those brazing apparatuses are either a direct current type or an alternating current type.
A direct-current type electromagnetic pump is adapted to generate a thrusting force to a conductive brazing filler metal, such as tin, over its path of motion by applying a magnetic field perpendicularly to the path of the conductive brazing filler metal and feeding direct electric current perpendicularly to both the path of motion and the magnetic field.
An alternating-current type electromagnetic pump is an electromagnetic induction pump which includes induction coils arranged on a plane along a path traveled by a conductive brazing filler metal and is adapted to generate a thrusting force to the brazing filler metal by feeding AC current having lagged phases to the induction coils, thereby generating a shifting magnetic field in the path traveled by the conductive brazing filler metal to permit the electromagnetic induction to generate electromotive force on the conductive brazing filler metal in its path of motion so that electric current generated by the electromotive force of the brazing filler metal flows in the magnetic flux in the magnetic field.
With a wave soldering device of a type which calls for force-feeding molten solder by means of a pump impeller rotated by a conventional motor drive mechanism, it is difficult to reduce the amount of solder, because of structural limitations in how small the solder bath can be.
To be more precise, as shown in FIG. 9, it is necessary to ensure sufficient width to provide sufficient clearance for the width

REFERENCES:
patent: 3797724 (1974-03-01), Flury et al.
patent: 3941088 (1976-03-01), Ronafoldi et al.
patent: 4392786 (1983-07-01), Merenkov et al.
patent: 4568012 (1986-02-01), Kakuhata et al.
patent: 5240169 (1993-08-01), Gileta
patent: 5816474 (1998-10-01), Flury

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