Why Do PCBs Need to Be Tested?

Why Do PCBs Need to Be Tested?

Testing is an important step in any PCB manufacturing process. It can help you catch mistakes to correct them and improve your overall performance.

Examination of your PCBs may reveal any defects that may occur during production or assembly. It can also be helpful to point out any design flaws that may be present. Examining PCBs after each stage of the process enables you to catch errors before moving on to the next stage, saving you time and extra money on the defective product. It can also help you catch single damage that affects one or more PCBs. This process helps ensure consistent quality between your boards and storage products.

Without proper PCB testing:

Without proper PCB testing in place, faulty boards may fall into customers' hands. If a customer finds the wrong product, your company may lose money through warranty payments or refunds. The customer will also lose the trust he once had in your company, and your reputation will be damaged. This situation can lead to missed opportunities if that customer moves his business elsewhere.
In the worst-case scenario, a malfunctioning PCB can cause injury or death if used in a product such as a medical device or a vehicle component. Such a tragedy could lead to serious damage to dignity and costly litigation.

Testing your PCBs can also help you improve your entire PCB manufacturing process. If you regularly notice an error, you can take action to correct that error at the process level. In this way, PCB testing can contribute to the further development of your business.

Printed Methods for Printed Regional Board Meeting:

What is a PCB test? Manufacturers must ensure that all components are assembled correctly to ensure that PCBs work properly. This is done through integration techniques and simple manual testing in automated testing using advanced PCB testing tools.

Manual visual inspection is a good start. For simple units, they can be all that is needed. At Electronic Manufacturing Services Group, we perform visual inspections by hand, magnifying all the boards we produce to meet all customer expectations. We also provide other testing services that include the use of advanced equipment. These tools can speed up the testing process and may be required for complex types of boards, such as multi-layered boards and those with a high number of components.

Visual Visual Examination:

An easy way to test a PCB is manual visual inspection (VMI). To perform this type of test, the worker looks over the board with a physical eye or magnification. They will compare the board with the design documents to ensure that all details are accessible. They will also check the default. The type of problems they are looking at varies depending on the type of board they are examining and its components.

It would be useful to do VMI after almost every step of the PCB production process, which involves assembling. MSG makes VMI under the expansion of all the boards we produce. You may also wish to follow VMI for the most advanced, complete testing.

The inspectors inspect almost every aspect of the board and look at the various features common to all. A standard PCB test checklist can include the following:

  • Ensure the board size is correct, and check the location wrap and warpage.
  • Check the size of the assembly to match the specification, and pay close attention to the size associated with the electrical connectors.
  •  The integrity and clarity of conductive patterns, and check solder bridging, open circuits, burrs and voids.
  • Check the quality of the surface, and check for the presence of holes, teeth, abrasions, pinafores and other impurities in print prints and pads.
  • Make sure all vias are in the correct location. Ensure they are not missed or misplaced, that their width is consistent with the specificity of the structure and that there are no voids or bumps.
  • Check the strength, durability and lightness of the pad plating, and check for any lump damage.
  • Check the coating quality.  The colour of the plating flux and whether it is even, solid and in the right place.
  • VMI has a few advantages over other types of testing. Because of its simplicity, it has a low cost. If you cannot get the right pitch, you do not want to be frustrated, so invest in a good capo. You can also do this test very quickly, and it is easy to add at the end of any process.

You need:

All you need to do is give them an outlet and the support they need to keep going. If you have the necessary expertise, this process can be beneficial. However, employees must have access to the design details and know what errors they should look for.

The power of this test method is limited. It does not allow you to check elements in the employee recognition line. Hidden solder joints, for example, cannot be viewed in this way. Employees may miss some minor mistakes. It is especially challenging to test complex boards with many small parts using this method.

Optical Automatic Testing:

You can also use a PCB test machine to perform visual inspections. This method is called automated optical inspection (AOI).

The AOI system performs experiments using several light sources and vertical or video cameras. Light sources illuminate the board at various angles. Cameras then capture still images or video boards, assembling them to form a complete picture of the unit. The system then compares photographic images with information about the board from a design specification or completed authorized unit.

2D & 3D:

Both two-dimensional and three-dimensional AOI tools are available. 2D AOI machines use coloured light from multiple angles and side angle cameras to monitor parts where height is a factor. 3D AOI objects are new and can quickly and accurately measure part length.
AOI can detect many of the same features that VMI can detect, including bumps, scratches, open circuits, reduced solder, missing parts and more. At EMSG, we sometimes use AOI, especially for complex boards and high-volume production runs. Our MIRTEC MV-3L AOI system can detect lead level defects in small parts such as 16-mil high. It can accurately detect bridge, insufficient solder, reversed polarity and damaged parts.

AOI is a stable, accurate technology and can detect many known PCB errors. It is useful in many stages of the PCB production process. It is faster and has VMI, and eliminates possible human error. Like the VMI, it will not be used to test components outside the line of sight, such as hidden connections under the grid frames (BGAs) and other types of packaging. It may also not work on PCBs with high-quality materials because some may be hidden or dignified.

Automatic Laser Test Measurement:

Another option for PCB testing is the automatic laser test (ALT) test. You can use ALT to measure the proportions of solder joints and solder joint deposition, and the appearance of various objects.

The ALT system uses a laser to scan PCB components and take measurements. As light reflects on parts of the board, the system uses a light source to determine their length. It also measures the thickness of the displayed beam to determine the appearance of the part. The system can then compare these values ​​with design specifications or with a board-approved as accurate to identify defects.

Using the ALT system is ideal for determining the amount and location of the solder adhesive and provides information about the alignment, viscosity, purity and other printing characteristics of the solder paste. The ALT method provides detailed information, which you can measure very quickly. These measurements are generally accurate but may be subject to interference or protection.

X-Ray examination:

With the rise of high-tech technology, PCBs are becoming more sophisticated. The boards can now be fully packed, packed with small parts and installed chip packages such as BGAs and chip-scale packages (CSPs) with which you can detect hidden solder connections. These features provide visual test challenges such as VMI and AOI.

To meet these challenges, you can use x-ray machines. Building materials absorb x-rays according to the weight of the atom. Rich nutrients absorb more, while lighter ones absorb less, allowing you to distinguish between the elements. Solder is made of heavy materials such as tin, silver, and lead, while many other components in PCB are made of lightweight materials such as aluminium, copper, carbon, and silicon. As a result, the solder is easily visible during x-ray examination, while many other components, including a substrate, lead and silicon composite circuits, are invisible.

Rather than looking like light, x-rays move in an object, making an image of it. This process allows you to see through chip packages and other components to check solder connections under them. X-ray examination will also allow you to see inside the solder joints to detect blisters you did not see using AOI.

X-Ray systems:

This systems can also detect the heels of solder joints covered by track during AOI. Also, with x-ray examination, there are no shadows to get in the way. For this reason, x-ray examination works best on crowded boards. You can perform an x-ray test manually using an x-ray tool or perform an automatic x-ray (AXI) test using an automated x-ray system.

X-ray testing is suitable for complex boards and offers skills that other test methods lack, such as seeing through chip packages. It also works well in testing dense PCBs and allows for detailed testing of solder joints. Technology is relatively new and sophisticated, and it can be very expensive. It may make sense to invest in x-ray equipment if you have high volume crowded boards with BGAs, CSPs, and other packages.

If your PCB design requires a different type of testing, EMSG can provide you with specialized testing services to meet your needs. Our internal team of experts is aware of the importance of quality control, and we will work with you to ensure that your PCB assembly meets all operating requirements. We want to work with you to determine if our PCB X-Ray testing service is the right process for your product.

By hqt001