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An automated discreet soldering system for plated holes of a printed wiring board, having a free piston type crucible mode of graphitic material, which is propelled along a guided path by pressurized nitrogen. A laser beam is directed along a path substantially coincident with the path of travel of

An automated discreet soldering system for plated holes of a printed wiring board, having a free piston type crucible mode of graphitic material, which is propelled along a guided path by pressurized nitrogen. A laser beam is directed along a path substantially coincident with the path of travel of the crucible to heat a susceptor surface for melting the solder therein.

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1. An apparatus for soldering conductive leads of electronic components in plated holes of a printed wiring board, comprising a supporting member having a vertically extending cylindrical bore formed therein, first means to hold a printed wiring board spaced from and above the supporting structu

1. An apparatus for soldering conductive leads of electronic components in plated holes of a printed wiring board, comprising a supporting member having a vertically extending cylindrical bore formed therein, first means to hold a printed wiring board spaced from and above the supporting structure in a position such that the axis of the plated holes are substantially parallel with the axis of the vertical bore, a crucible assembly having a chamber for holding a quantity of solder slidably mounted in the vertical bore, second means in communication with the crucible assembly in the bore to apply force sufficient to lift the crucible upwardly in the bore to soldering position beneath a printed wiring board, third means to apply a beam of energy along the axis of the cylindrical bore to melt solder in the crucible chamber at times when the crucible assembly is in a selected position, fourth means to release the applied lifting force to cause the crucible assembly to slide downwardly in the bore to a predetermined position subsequent to each application of molten solder, fifth means to deposit a solid piece of solder in the crucible chamber at times when the crucible is in a predetermined position; and sixth means to change the relative position of the supporting member and a board held by the first means at times when the crucible is in a predetermined position to place a different plated hole of the board in registry with the crucible chamber. 2. An apparatus according to claim 1 wherein the third means comprises a second bore in the supporting member that is oriented to communicate at one end with the vertical bore and at its other end with a source of energy for melting the solder, a deflector mounted at the juncture of the vertical and second bores to direct the energy axially through the vertical bore and the central opening of the sleeve and the hollow piston to the susceptor surface of the crucible. 3. An apparatus according to claim 1 wherein the crucible assembly comprises a hollow piston to which a crucible member having an integral susceptor surface is connected, said crucible susceptor surface and hollow piston forming an inverted chamber through which the energy beam is directed, said susceptor surface being of greater cross sectional area than the crucible chamber for holding the solder. 4. An apparatus according to claim 3 wherein the hollow piston includes a lower skirt portion of graphitic material and a thermal insulative member interposed between the crucible and the skirt portion for minimizing the transfer of heat between the crucible and the skirt portion. 5. An apparatus according to claim 3 wherein said second means comprises a sleeve fixed in the vertical bore, said sleeve having an upper radial surface which supports the hollow piston at its lowermost position, said sleeve having a central opening therethrough which the energy beam is directed and a bore radially offset above and from the central opening in communication with the radial surface, and means connected to the bore at its other end for supplying fluid under pressure to the crucible assembly. 6. An apparatus according to claim 1 wherein the fourth means comprises a valve operative when open to release fluid pressure from beneath the crucible assembly and operative when closed to seal the vertical bore of the supporting member, and a passage from the interior of the crucible assembly to its outer surface to release pressure from beneath the crucible assembly at times when the crucible exceeds a predetermined upper position. 7. An apparatus according to claim 3 wherein the crucible member has internally tapering chambers, and is made of graphitic material. 8. An apparatus according to claim 4 wherein the thermal insulative member has a frustroconical configuration that is threaded at its narrow upper portion, and the crucible member is threaded to mate with the threaded portion of the insulative member. 9. An apparatus according to claim 1 wherein the fifth means comprises a stationary shearing member having a bore therein for receiving a length of solder, a shearing member slidably mounted on the stationary member having a bore therein into which a length of solder extends at times when the shearing members are in a retracted position, said slidable member being operative in cooperation with the stationary member to cut a piece of solder extending into its bore at times when the shearing member slides from its retracted position, and means for applying fluid pressure against the cut piece of solder to hold the solder against the wall of the bore while the shear is carrying the solder to be in registry with the crucible assembly, and means to force the cut piece of solder out of the bore upon release of the fluid pressure. 10. Apparatus according to claim 5 wherein the means for supplying fluid under pressure comprises means to supply nitrogen gas. 11. An apparatus for soldering conductive leads of electronic components in plated holes of a printed wiring board, comprising a supporting member having a vertically extending cylindrical bore formed therein, first means to hold a printed wiring board spaced from and above the supporting structure in a position such that the axis of the plated holes are substantially parallel with the axis of the vertical bore, a crucible assembly having a chamber and including a susceptor surface for holding a quantity of solder slidably mounted in the vertical bore, second means in communication with the crucible assembly in the bore to apply force sufficient to lift the crucible upwardly in the bore to soldering position beneath a printed wiring board, third means including a second bore in the supporting member that is oriented to communicate at one end with the vertical bore and at its other end with a source of energy for melting the solder, a deflector mounted at the juncture of the first and second bores to direct the energy axially through the vertical bore and the central opening of the sleeve and the hollow piston to the susceptor surface of the crucible to apply a beam of energy along the axis of the cylindrical bore to melt solder in the crucible chamber at times when the crucible assembly is in a selected position, fourth means including a valve operative when open to release fluid pressure from beneath the crucible assembly and operative when closed to seal the vertical bore of the supporting member, and a passage from the interior of the crucible assembly to its outer surface to release pressure from beneath the crucible assembly at times when the valve is closed and the crucible exceeds a predetermined upper position to cause the crucible assembly to slide downwardly in the bore to a predetermined position subsequent to each application of molten solder, fifth means including a stationary shearing member having a bore therein for receiving a length of solder, a sliding shearing member slidably mounted on the stationary member having a bore therein into which a length of solder extends at times when the shearing members are in a retracted position, said slidable member being operative in cooperation with the stationary member to cut a piece of solder extending into its bore at times when the shearing member slides from its retracted position, and means for applying fluid pressure against the cut piece of solder to hold the solder against the wall of the bore while the shear is carrying the solder to be in registry with the crucible assembly, and means to force the cut piece of solder out of the bore upon release of the fluid pressure to deposit a solid piece of solder in the crucible chamber at times when the crucible is in a predetermined position; and sixth means to change the relative position of the supporting member and a board held by the first means at times when the crucible is in a predetermined position to place a different plated hole of the board in registry with the crucible chamber. 12. In a system for applying molten solder to a plated hole from the underside of a printed wiring board, the improvement of a solder applying assembly, comprising a vertically oriented cylinder, a cylindrical crucible assembly having a solder carrying chamber and a susceptor surface, said crucible assembly being mounted slidably in the cylinder, means to apply fluid under pressure to prepare the crucible assembly upwardly in the vertical cylinder, means to melt solder in the crucible chamber, and means to hold a printed wiring board in horizontal position above the crucible assembly such that the crucible chamber registers with a plated hole for applying the solder. 13. In a system according to claim 12 wherein the improvement of the solder applying assembly further comprises, means to direct an energy beam through the vertical cylinder to the susceptor surface for melting solder in the crucible chamber. 14. In a system according to claim 12 wherein the crucible assembly of the improvement of the solder applying assembly comprises a susceptor surface having a cross-sectional area larger than the crucible, said crucible including the susceptor surface being constructed of graphitic material.