Functional testing, also known as FCT testing, is the last manufacturing step of PCB creation. Essentially, functional testing makes sure the PCB works correctly. Functional tests examine the entire assembly rather than individual components. The tests simulate the final electrical environment where the PCB will reside. For example, if your PCB will rest in a computer slot, the functional test will recreate a similar slot to test its functionality. Then, you can uncover potential problems with the product before opening it to consumers.

Tools for functional tests often include:

• Connective interface
• Cables
• Central processing unit
• Monitors

Functional tests vary by product specifications. The length and type of the test depend on factors like:

• How much of the PCB is being tested
• The needed inputs and stimuli
• Desired results
• Testing parameters

During a functional test, you check each component to ensure it’s in working condition. If you’re wondering how FCT testing is done, you can use various techniques to test the board. Here are some common ways to functionally test PCBs:

Test Procedure List Creation

Deciding which tests you’ll perform is usually the first thing you do before starting the functional testing procedure. List the techniques you plan to use while testing the board.

For example, you might make a list of components and how you will test them during functional testing:

• Resistors: Resistors transmit the electric current that powers a PCB. You can use a multimeter or other device to test resistors. Touch the multimeter’s probe to each resistor lead, then check the readings.
• Sensors: These devices can sense alterations in the environment and create an electrical signal in response. You could also use a multimeter or similar device to test a sensor.
• Capacitors: These components hold an electric charge on the board and release it when necessary. You could also add this component to your testing list.

As you progress through your functional tests, you can use your list to ensure you complete every option.

Voltage Meter Testing

The correct voltage is essential for a PCB to function correctly. The voltage reflects the power routed to the circuit. Whether a high-voltage or low-voltage unit, you must test the levels to ensure the board is safe to use.

A voltage meter test ensures the voltage levels of the PCB are at appropriate amounts. During this test, you place a voltage meter at every point on the board and ensure the reading is correct. Technicians then power on the board for the first time to ensure it powers properly.