Dual track stenciling system with solder gathering head

Abstract

A dual track stencil system includes a first set of rails and a second set of rails, each of the rails being independently controlled for allowing for independent movement of circuit boards through the stencil system for processing. The stencil system includes a working area, at which the circuit boards are stenciled. A stencil, having two patterns, each aligned with a respective working area of each track is suspended above the dual track system. In one embodiment, a solder dispensing unit including a squeegee arm is suspended above the stencil, parallel to and centered between the two tracks. During operation, a circuit board enters the working area, is raised to engage with the stencil, and the squeegee arm traverses that portion of the stencil pattern currently engaging the board, thereby dispensing solder through the pattern and stenciling the board. The stencil system operates to process two boards on one track before advancing to the second track for processing another pair of boards. In another embodiment, the solder dispensing unit includes a squeegee arm with a solder gathering head. During operation using the squeegee arm with the solder gathering head, two circuit boards are fed to the working area, and both of the circuit boards are serially processed, with excess solder being removed from the board after the processing of each of the boards. In a further embodiment, a solder dispensing head is used in the stenciling system, with the solder dispensing head containing solder and extruding solder through the stencil onto the circuit board in repetitive passes, the number of passes depending upon the width of an opening in the solder dispensing head. Because the solder gathering squeegee arm and the solder dispensing head retain the solder within the solder distributing unit, there are no order of processing constraints with respect to the stenciling of the circuit boards on the dual rails. The rails of the dual track system are advantageously moveable to allow for variable width boards or operation of the system in single track mode. The stencil system design may be adapted to make the dual track system a recirculating track, capable of supporting pallets for transport and printing of delicate materials. In addition, the stencil system design may be adapted for processing boards in parallel, where the boards are received simultaneously or staggered, placed at a stencil position, and printed with one stroke of the squeegee head.

What is claimed is:  
     
         1 . A stenciling system for use in a circuit board manufacturing process, comprising: 
 a plurality of sets of rails, each of said plurality of sets of rails for supporting and advancing a plurality of circuit boards through said stenciling system; and    a solder gathering squeegee arm, disposed over said plurality of sets of rails, for depositing solder on a stencil during stenciling of a first circuit board on a first one of said plurality of sets of rails, and for removing excess solder from said stencil after said stenciling of said first circuit board.