In typical electronic manufacturing lines, printed circuit boards (PCBs) are assembled and tested individually. Multiple PCBs are then assembled into finished products, which are tested. The test engineers will set goals for each type of test in order to plan for test and troubleshooting equipment and train operators for the production phase. Usually, PCBs are tested on automatic in-circuit testers (ICTs)，which remove some of the assembly or part defects. The PCB test programs and the effort to develop them depend on these goals. A high yield in PCB test will reflect a higher turn-on ratio at the product level, saving the company valuable product test time and resources. Final assembly of the electronic product is accomplished from these tested PCBs and other components，such as power supplies and display devices, and turned on for final test.