Patent ID: 6073817
Filing Date: 2000-06-13
Classification: B22D

Abstract:
A pump for dispensing molten solder on a planar substrate comprising a pump body defining a molten solder reservoir;a pumping chamber in said pump body, said pumping chamber being defined in part by a flexible diaphragm;a throttle orifice providing communication between said reservoir and said pumping chamber;at least one molten solder dispensing nozzle, a channel in said pump body connecting said pumping chamber and said nozzle;a movable throttle adjacent said throttle orifice and defining a throttle gap through which molten solder passes between said reservoir and said pumping chamber;a gas pressure passage communicating with one side of said diaphragm whereby said diaphragm is deflected into said pumping chamber;a stop adjacent said diaphragm which engages said diaphragm when said diaphragm deflects a predetermined amount;a pneumatic actuator means communicating with said gas pressure passage for adjusting said movable throttle to vary the flow area of said throttle gap; andvalve means in said gas pressure passage for controlling distribution of gas pressure to said pneumatic actuator and to said one side of said diaphragm during a molten solder dispensing cycle;said throttle being calibrated to provide an annular throttle gap of variable size during said dispensing cycle whereby the momentum of molten solder moving through said throttle gap substantially counteracts the momentum of molten solder moving through said nozzle at the instant said diaphragm engages said stop.