Printed circuit board fixtures
Electronic Design & Manufacturing based in Lynchburg Virginia, manufactures circuit boards for a variety of electronic devices. Their ISO 9001-certified operation is clean and quiet, with rows of machines to assemble, solder, inspect, and trim all sizes and shapes of circuit boards-as large as 18" x 20" and as small as a dime.
Trimming printed circuit boards (PCB) out of the substrate panel on a CNC machine or with a router is the last process in the manufacture of PCBs. The trim path at the trim station leaves just a small tab of material so multiples on a substrate panel can be easily separated for placement in the customer's product.
EDM adheres to strict quality standards throughout the PCB assembly, but the faults at the trim station were the most detrimental to the yield of the batch. "We were not satisfied with the acceptance rates of each batch in the test and route stage," explains Robert Roberts, chief technical officer. "We needed a way to assure the boards did not shift during this operation so that the routing was clean and thorough. Given the variety of product we test and route, the most practical option was to have a local vendor adapt the workstations."
AIT studied the process time and acceptance rate of several sizes and batches of boards. Noting that delicate PCBs were prone to damage, AIT then engineered and fabricated a CNC-machined PCB precision fixture in aluminum and brass. The two-part hold down fixture secured the substrate during final electrical inspection and scoring by the router tool. Each fixture was custom-sized for the substrate panel. Brass pins aligned the substrate and a path-punched top plate protected the areas of the PCB inside the trim path.
Overall acceptance rate increased significantly with the hold down fixtures in place-without increasing operator involvement or cycle time for the operation. "The solution AIT engineered is simple and effective," Roberts said. "The accuracy of the machining on the AIT fixtures contributes to the consistent results we are still experiencing years later."