Electrodynamic pump for dispensing molten solder

Abstract

A system is provided for depositing an extremely small amount of solder on a printed circuit board by varying the direction of an electric current applied to a solder stream. The force exerted on the solder can be substantially instantaneously reversed without the necessity of changing the form of the energy applied to the solder from electrical to vibratory, ultrasonic, magnetic, or the like. The direction and magnitude of the force is related to the cross product of an electric current vector and a magnetic field vector (F=I.times.B). A programmable current source is used to place an electric current through the liquid solder as it is flowing through a conduit. A magnetic coil is disposed adjacent the conduit in order to provide a magnetic field in the same plane as the electric current. The conduit supplies liquid solder to a nozzle which then deposits a droplet of solder onto a printed circuit board. Therefore, as the current is applied, in a first direction through the solder, an outward force is exerted on the solder. When the direction of the current is reversed, then the direction of the force exerted on the solder is also reversed, and an extremely small droplet of solder is "snapped off" of the solder stream.

Dependencies are inferred from the claim text.