Solder preform pick-and-place machine and operation

Abstract

Ten holders containing preforms are stacked on a rectangular bottom frame with different sized threaded posts of the bottom frame extending up through the hole and slot in opposite corners of each holder. An empty holder and then a dust cover with apertures at opposite corners are similarly stacked on the bottom frame to hold and protect the preforms. A top frame with apertures at opposite corners is positioned on the posts. The stack is compressed between the top frame and the bottom frame by screwing nuts onto the threaded posts to form a carrier in which the cavities are sized relative to the preforms to hold the preforms in position during transport to a pick-and-place machine without contaminating or damaging the delicate coating of dry flux. The holders are unstacked and positioned on different sized posts extending upward from a pick-and-place machine. A robot arm with a rubber tipped vacuum probe picks up the preforms without damage or contamination and places them on a circuit board, grippers of the robot arm pick up and position a component on an induction coil to heat it up sufficient for reflow soldering, and then move the component onto the preform on the circuit board for reflow soldering. The circuit board can be used without cleaning with solvents or CFC's, thus reducing process steps and reducing environmental hazards.