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How to Perform Functional Testing?

Functional testing is performed in the last step of PCB assembly manufacturing process. A functional test emulates the operational environment to ensure the PCBA’s correct functionality. The operational environment may consist of a device that communicates with the PCBA DUT. Typically, the DUT’s power supply and software test program will load the necessary parameters to make the DUT work properly.

Functional testing will verify the functionality of your PC board assembly. It will do this by applying a range of different signals and currents to stimulate the board’s behavior based on testing software developed for the board, and then measure how the PCBA reacts. It will detect both analog and digital signal problems, including distortions, incorrect currents, and signal timing issues.

The printed circuit board assembly (PCBA) may be subjected to a sequence of signals and power supply voltages. Responses are monitored at specific points to ensure correct functionality. All testing is performed according to the customer test engineer’s specifications and procedures.

PCBA Functional Testing Fixtures

Many different test fixtures have been developed for functional testing of a PCBA (PCB assembly). Electrical connections may be made with connectors present on the PCBA or by test probes that contact test points defined by the PCB designer. Connectors on a test fixture are usually modified to allow for ease of mating and de-mating of the fixture’s connectors and the connectors on the PCBA to be tested. Connectors and the connectors on the PCBA to be tested. Connectors on the test fixture are also usually made easily replaceable, since they can wear out quickly with the multiple mating and de-mating cycles of production testing.

When making direct contact to test points on a PCBA, probes under the PCBA are typically fixed and the test fixture applies hold-down force to the top of the PCBA for reliable electrical connections to the test probes. If the PCBA being tested has test points on both sides of the board, then two probe plates are required, both of which must be precision aligned to each other and to the PCBA under test. With double-sided probing, the PCBA under test is typically fixed in place and the probes move in from both top and bottom when the fixture is operated.