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6 Popular PCBA Testing Methods, Explaination and When to Use

PCBA testing allows manufacturers to check the quality and reliability of their printed circuit board assemblies. By testing individual components as well as the assembly as a whole, manufacturers can identify faults and correct them before they result in costly field failures. What re these tests and how are they performed?

PCBA Testing

PCBA testing is used to describe the methods used to ascertain if a newly assembled printed circuit board is working as intended and meets all the design specifications. The main goals of testing are to identify incorrect or faulty components and assemblies, and to investigate the cause of any problems.

This can be done in a number of ways, but the most common methods are functional testing, in-circuit testing, and visual inspection. These tests may also be performed manually or with the help of automated testing equipment.

PCBA testing help to ensure products are high quality. It builds customer confidence and can save you from costly field failures. The most important PCB assembly testing methods are explained next.

PCB assembly testing jig
PCB assembly testing jig
Resource: https://youtu.be/ZLBto2TWTqg

PCBA Testing Methods

Because of the many different parameters and manufacturing standards that PCB assemblies must meet, a variety of tests have been developed to cover all the bases. Manufacturers use them to confirm the quality of their PCBAs, while customers must be aware of the type of test used. The most common PCBA testing methods are:

1. Manual PCBA Inspection

This is the simplest and most basic form of PCBA testing. In this testing method, trained operators use magnifying glasses and other tools to inspect the soldering and look for any potential problems.

Manual PCB assembly inspection is slow and can be error-prone, so it is often supplemented with automated optical inspection or AOI.

The manual inspection method is also normally used when there are not many PCBAs to test, as that would take a very long time and increase the possibility of many errors going undetected.

2. Automated Optical Testing

In this testing method, several cameras and ultraviolet or other light sources are used to inspect the PCB for any potential defects. The images captured by the cameras are then analyzed by a computerized system that looks for any anomalies.

AOI can be used for both 2D and 3D inspection of optical PCBs, making it very versatile. It is also relatively fast, which makes it ideal for high-volume production.

3. In-Circuit PCBA Testing

The in-circuit test is also called bed-of-nails PCB assembly testing, and is a method in which every pin of every component on the PCB is tested for correct electrical continuity and connection.

In this PCBA testing method, test probes are used to check the continuity and functioning of all the components on the PCB. This is done by connecting the test probes to specific points on the PCB.

In-circuit testing is very effective at identifying faults, but can be quite slow. It is therefore mostly used for lower-volume production runs or alongside other testing methods.

4. Flying Probe PCBA Testing

When using this assembled PCB testing procedure, the tester normally holds two probes that they move around the PCB to make contact with the required test points.

Flying probe PCB testing is very versatile as it can be used with a broad range of tests. It’s also easy to carry out, offers good coverage and doesn’t require a lot of space.

The main drawback of this method is that it can be quite slow, as the probes have to physically move around the PCB assembly. For that reason, it’s only suitable for small runs or prototype PCBAs.

5. Functional PCBA Testing

This is a very important type of PCBA testing, as it tests to see if the PCB assembly is actually performing the function it was designed or made for. The test is done using test software as well as a range of printed circuit board assembly testing equipment.

The functional test is carried out by using the PCB assembly to carry out the required function, and then observing the results. This can be quite time-consuming, so it is often only used for lower-volume production runs or prototyping PCBs.

6. X-ray Inspection Test

This is a non-destructive test that uses X-rays to examine the solder joints on a PCB assembly. X-ray inspection is very effective at identifying faults, as it can see inside the PCB. It is also relatively fast, which makes it ideal for high-volume production

But despite its many advantages, X-ray inspection can be quite expensive, as it requires specialized equipment. It’s commonly employed in the testing of multi-layers PCBs, as these are more difficult to inspect visually.

As you can deduce from the above PCBA testing methods, there are many ways to test a PCB assembly for defects. The best method to use will depend on a number of factors, such as the type of PCB, the volume of production and the budget.

But one thing is for sure –PCBs should be tested before they are used in any applications. That helps to, one, ensure that they are of high quality and two, and identify any potential problems so that they can be fixed before it becomes too late.

Conclusion

PCBA testing is an essential part of the printed circuit board manufacturing process and should not be overlooked. With the help of this guide, you should now have a good understanding of the different types of tests that can be carried out on a PCB assembly. So, whether you’re testing a prototype or a production run, you should be able to choose the right method for the job.

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