Spraying system for spraying printed circuit boards

摘要

A spraying system comprises a conveyor for conveying a series of boards through a spraying station, spray nozzles at the spraying station and a mechanism for controlling spraying from the nozzles onto the board located at the spraying station. The control mechanism comprises a sensor for sensing the speed of the conveyor, a photoelectric cell for sensing the presence of a board on the conveyor and a logic unit which is positioned and arranged for calculating the length of the board in response to signals from the sensor and photoelectric cell. The logic unit is arranged to activate a supply of liquid flux to the nozzles when the leading edge of the board reaches the spraying station and the nozzles are reciprocated across the conveyor as the board is advanced. Sensors control the nozzles so that spray is delivered only onto the board and is stopped as the nozzles reach the side edges of the board. The system provides controlled spraying only onto the board and eliminates wastage and reduces atmospheric pollution. The system is primarily intended for the flux spraying of printed circuit boards but is not restricted to this use.