Optimum Design Associates manufactures high-density circuit boards, some of which are installed into higher-level assemblies. A major step in the assembly process is board-level functional test. Typically, functional testing is designed by the OEM customer, and the fixtures and procedures are then passed to the contract manufacturer.
Last year, facing a customer request for higher unit volumes, a functional test fixture provided by the customer proved inadequate, causing a throughput bottleneck. In this case, the “fixture” was actually a complex cable harness with multiple connectors terminated by hand solder and no strain relief. It supported three unique boards, which are assembled together for insertion into the higher-level assembly. Like many functional tests, this harness was originally put together to support debug, and no resources had been devoted to converting it into a true manufacturing tool. “It was a slow process,” said one of the floor managers. “Multiple boards were going through one station, failures were harder to find, and the wiring on the fixtures was getting worn out do to too much handling.” When encountering a failure, the operator often had to determine whether it was the DUT or the cable that was failing.
