Basic Knowledge of In-Circuit Testing: What is the Difference Between Fixture-Based and Flying Probe Testing?

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There are two probing methods for in-circuit testing (electrical inspection of printed circuit boards): fixture-based and flying probe. **Fixture-based** A test fixture with embedded contact probes makes contact with the test board, and all probes simultaneously touch designated test points on the board. In this state, inspections of each electronic component are performed while switching the measurement lines with relays. For the boards being inspected, it is necessary to create a program that combines each inspection and to manufacture a dedicated fixture, which poses challenges in terms of cost, speed, and storage space. **Flying Probe** Multiple arms holding probes perform probing at any point on the board. Although probe movement time is required, resulting in longer inspection times compared to fixture-based methods, there is no need for fixtures, and setup can be changed simply by swapping programs. This can lead to time and cost reductions when viewed from the overall process perspective. It is also suitable for inspecting boards in low-volume, high-variety production. The coordinates of the test points can be changed arbitrarily, making it easy to accommodate partial design changes to the board. It is also used for prototype board inspections and failure analysis.

Circuit Board Inspection Equipment