Printed circuit boards are in just about anything that’s electronic, from computers to cars to transformers. Because they’re so prevalent, and because they’re such a crucial component (they’re basically the soul of a device), it’s critical that PCBs are manufactured properly. And for that to happen, PCB designs must go through a test run before final fabrication.

But what does PCB testing look like? And what mistakes do designers run into when designing test PCBs? We’ve put together a guide to the most common PCB testing methods so you can find out.

Testing Method One: Visual Inspection

The cheapest and easiest PCB testing method is visual inspection. Trained and experienced technicians use their eyes or a magnifier to scout out defects. Some flaws visual inspections uncover are solder defects, missing components, and incorrect component orientation. Because these inspections are done by imperfect humans, they are susceptible to error and lengthy completion times.

Testing Method Two: In-Circuit Testing (ICT)

In-circuit testing is an automated process where probes send electrical currents through specific testing points on the PCB. These currents expose electrical shorts and open circuits.

Testing Method Three: Flying Probe Testing

As another automated process, flying probe testing allows technicians to evaluate the orientation of diodes and transistors, and measure voltages. If there is a change to the PCB’s components or design during the process, the software can accommodate the changes with a simple software update.

Testing Method Four: Burn-in Testing

Burn-in testing allows technicians to accurately analyze a PCB’s performance and uncover hidden defects. During this process, PCBs endure extreme conditions to uncover triggers (temperature, voltage, operating frequency, etc.) that may lead to premature failures and to test the board’s load capacity.

Testing Method Five: Functional Testing (FCT)

Last in our guide to the most common PCB testing methods is functional testing. Depending on the need, the test can be simple or complex. This testing method replicates the environment the PCB will operate in, so technicians are able to get a better idea of how well the PCB will work and whether there are any design flaws. 

Which PCB Components Are Tested?

During the testing process, various components are tested to ensure the PCB functions as it should. No matter which testing method is used, some of the most common components that are tested include:

• Capacitors

• Diodes

• Resistors

• Fuses

• Transistors