What Is PCB Functional Testing?

What Is PCB Functional Testing?

Printed circuit boards (PCBs) are essential tools for many industries. PCBs allow you to connect electronic components using conductive pathways. Copper sheets are laminated onto circuit boards and facilitate the movement of electric currents. In turn, these tools become the building blocks for countless electronic devices in many industries.

PCB functional testing is a crucial aspect of their creation. Performed at the end of manufacturing, the tests ensure the PCBs will operate correctly. They serve as the last step between manufacturing and the market.

What is PCB functional testing, and how is functional testing done? Learn more information about PCB functional testing.

What Is PCB Functional Testing?

Common Functional Testing Techniques

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.

Load Testing

These tests measure a board’s capability to withstand certain pressures and changes in other parameters. The test makes sure the board can handle its intended capacity. You could test the board’s operating capacity when these aspects change:

  • Temperature: Temperature maintenance is crucial for PCBs. If the board gets too hot, it could degrade the performance or cause it to break down. The maximum temperature a board can reach depends on its materials. During load testing, you could put the board into conditions that simulate heat and monitor how well it responds.
  • Current: You can determine a PCB’s current capacity by using a cross-sectional area of trace and monitoring the temperature rise. In load testing, technicians check the board’s current to ensure it’s at the right level.
  • Operating frequency: PCB functionality also depends on the operating frequency. The boards are classified as high-frequency or low-frequency. You can also ensure the operating frequency meets manufacturing requirements during functional testing.

QC Testing

Lastly, quality control (QC) testing ensures a PCB meets the specifications and regulations of the product. Because functional testing is the final step of PCB manufacturing, QC tests examine the finished product. During this test type, you check the PCB’s design and functionality. You then ensure these meet industry or federal standards. For example, you could measure if a board meets ISO 9001:2015 requirements.

Quality control testing might also involve a procedure like automated optical inspection (AOI). This thorough test examines your board’s components for potential defects. It magnifies all the components so you can inspect them more precisely. For instance, it checks for incorrect solder amounts and missing or damaged components.

Why Testing Is Crucial and How It Matters to You

No matter what type of electronics functional testing you use, it benefits your PCBs greatly. By using functional tests, you can guarantee a PCB is fit for sale. They also prevent costly replacements in the long term. You can maintain manufacturer quality and reputation with consistent tests. 

Functional tests can identify issues like:

  • Power issues: PCBs require stable power to function correctly. Functional PCB tests can examine power strength and point out issues with low frequency or rippling during operation.
  • Signal distortion: Tests can also display problems with signal distortion or failure during use.
  • Inaccurate voltage: Many factors could cause incorrect voltage, from incorrect component placement to missing a part entirely. A functional test can display these issues and let you get started on a solution.

By using functional tests for your PCBs, you can maintain the quality of your products. Your customers can save money and time by trusting their product is of the highest quality right when they buy it. Electrical functional testing is an essential step for PCB production.

What Is PCB Functional Testing?

Learn More About EMSG PCB Testing Services Today

FCT testing is crucial for product quality. At Electronic Manufacturing Services Group, Inc., we understand the importance of PCB functionality testing and offer a wide range of full-service testing solutions. Our inspections magnify units and ensure they meet customer and manufacturer standards. We also provide product-specific tests for individual units, ensuring the highest quality for your product.

We never sacrifice quality for speed and guarantee thorough PCB tests. After a consultation with one of our experienced engineers, we can put together a detailed quote that explains our testing plan.

To get started with EMSG’s testing services, contact us today.