5 Common Types of Post-Manufacturing Testing in PCB Production

Throughout the printed circuit board (PCB) production process, and especially towards its end, one of the most vital steps involves putting the circuit board through multiple, rigorous rounds of testing to ensure the overall quality and functionality of the board.

If a PCB has unresolved issues when it gets to this phase, such as certain components being out of place, this can lead to it functioning sub-optimally or even completely malfunctioning. The testing phase of the PCB production process is meant to prevent this from happening. When a PCB passes these tests, this guarantees it is reliable and defect-free, which significantly lowers the risk of failure.

Putting PCBs through a rigorous testing process is necessary to reduce costs and unnecessary delays by minimizing the need for expensive reworks and replacements. It can be costly to repair or replace problematic components after the fact rather than during production.

Of course, finding and fixing issues during the PCB production process helps improve customer satisfaction and boost your brand’s reputation, as customers expect to receive high-quality electronics that function properly. Aside from keeping your customers happy, it is also necessary to perform certain kinds of PCB testing to comply with regulations and avoid facing financial and legal penalties.

Key Types of Post-Manufacturing Testing for PCBs

Many tests can be used to objectively evaluate the quality of a printed circuit board and determine whether it contains issues requiring further investigation. Although these tests follow different procedures and focus on various factors, the goal of each is to ensure that the PCB functions optimally.

1. Automatic optical inspection

To find defects in PCBs, automatic optical inspection (AOI) testing utilizes the optical signal detected by either a single camera or multiple cameras. Once high-resolution images are captured by these cameras, they are compared with images of a model board or with an image database that contains views of both good and defective boards, automatically comparing these images to seek out potential issues.

This kind of testing can make it easy to spot various issues related to assembly early on, including shorts, thinning soldering, open circuits, and scratched traces. AOI testing makes it easier to spot issues in a quick and efficient manner by highlighting problems that would likely take much longer to find during a manual examination.

However, this method only works for PCBs with soldering, connections, pads, and traces that are optically controllable, and since it is a passive form of testing, it can only detect defects present on the surface of the PCB.

2. In-circuit testing

One of the most common types of PCB testing is in-circuit testing (ICT). This is a capacitance test that involves checking a PCB for open and short circuits, as well as inspecting for component values and IC operation.

First, a number of small, spring-loaded pogo pins must be pressed into various parts of the nail bed in order to check the board’s solder connections. To begin the test, the circuit board must be pushed down on a bed of probes, otherwise known as a “bed of nails,” so that circuit testers can access the circuit through pre-constructed access points.

ICT testing is a good option when you do not expect many revisions to be necessary. However, this kind of testing is only possible if your board has the right pads built with a design-for-manufacturing testing goal, which must be designed to support it from the beginning of the PCB production process.

3. Flying probe testing

Another test that can be used following PCB production, specifically to check for issues like short circuits, open circuits, diode problems, capacitance, resistance, and inductance, is flying probe testing.

To perform a flying probe test, you need a generic board holder and at least one probe. Software is used to control these probes, prompting them to access the board’s nodes one by one and check for errors.

The main benefits of flying probe testing are that it requires no test fixture, and it is easy to set up this kind of test quickly. However, flying probe tests take longer to perform than in-circuit testing, and these tests do not work well if you have a complex circuit.

4. Functional testing

Functional tests allow manufacturers to verify that a product works as intended. This kind of testing requires the use of test equipment and fixtures while following standard specifications, such as Underwriters Laboratories (UL) and Mine Safety and Health Administration (MSHA).

During functional testing, power is applied to the PCB, and tests are run to simulate its operational environment so that signal integrity, component functionality, and communication between different parts of the board can all be checked.

The downside of functional testing is that it takes some time to perform. However, this is worth it if you want to get a good overview of your PCB’s quality and spot any issues that could impact its functionality or longevity.

5. Burn-in testing

To detect failures in your PCB and assess its load capacity, consider burn-in testing. During burn-in testing, a specialized device is used to force power through your PCB at maximum capacity for anywhere from 48 to 168 hours.

In some cases, a PCB may also be subjected to other stress conditions, such as elevated temperatures or voltages for extended periods, to simulate accelerated aging for the purpose of detecting early failures that might not be apparent under typical operating conditions.

While this kind of testing is effective, it can be quite intense and should be performed with caution, as it can result in the destruction of other components.

Contact Circuits Central for Expert Post-Manufacturing Testing for Your PCBs

Post-manufacturing testing is a critical component of the PCB production process and is necessary for the quality assurance of your PCBs. If you want to improve the quality of your PCBs and reduce your time to market by ensuring they are free of common issues like short or open circuits, scratched traces, and soldering problems, Circuits Central can help you perform many kinds of post-manufacturing testing to evaluate these parameters.

As skilled and experienced PCB experts, we are equipped to handle AOI testing, X-ray testing, functional testing, JTAG testing, in-circuit testing, flying probe testing, burn-in testing, and more. Through these tests and visual inspections, we can provide valuable feedback on any issues that require further investigation or reworking.

For more information about the variety of post-manufacturing PCB testing that we can perform, or to learn more about the other stages of PCB production that we can provide expert assistance with, call Circuits Central at 1-888-602-7264 or contact us here.