An apparatus for placing solder bumps on a mold plate includes: a solder fill head configured for dispensing molten solder onto the mold plate, the solder fill head also configured for relative movement over the mold plate; and a control mechanism configured for controlling positions of the solder fill head relative to the mold plate. The control mechanism includes: a control input signal containing data about an ideal positioning of the solder fill head; a plurality of sensors positioned on the solder fill head, the sensors configured for providing data about a gap between the solder fill head and the mold plate; a position controller configured for receiving the gap data and comparing the gap data with the control input signal, wherein the position controller provides an inequality signal if the gap data and the control input signal are not equal; an amplifier configured for receiving the inequality signal and amplifying it; and an actuator configured for receiving the amplified inequality signal and controlling movement of the solder fill head in response to the inequality signal received. The control mechanism may be a servo control mechanism. The sensors may be gap sensors.