How To Recognise Five of the Most Common PCB Failures

How To Recognise Five of the Most Common PCB Failures – Whether you’re an OEM or assembler, you will have encountered printed circuit board failures at some point. These failures can be very frustrating to a company, as there is the risk of losing time, products, reputation and money. Failures in PCBs need to be resolved quickly to ensure the issue doesn’t reoccur and cause constant problems.

When a PCB failure happens, there are failure analysis tests that can be done to identify the problem and solve it. These tests will identify the existing weaknesses and the failure analysis data report will provide an OEM or assembler with vital information for making better products.

These failures are easy to spot once you know how the defects happen, and then you can take steps to get the right failure analysis tests. But not everyone knows what those failures are – so we’ve compiled a list of six of the most common PCB failures.

1. Chemical fluid leakage

The presence of any chemical fluid that has leaked from a component can seriously damage the PCB and cause failure. Most chemicals are removed in the manufacturing process, but often trace elements are left behind. Inside the packaging of a component, leaks can happen, which cause rapid aging of the semiconductor or package. This chemical leakage can eventually cause shorts or become corrosive.

2. Issues with the soldering process

Solders are the part that provides the necessary means of contact between the component and the circuit, without it the PCB would not work. There are a few solder issues that can cause failure, but the most common are flux contamination and poor processing conditions. Some flux residues can absorb moisture which can become conductive, causing short circuits. If the solder process is not properly set up and controlled, it can lead to open joints and contaminated solder

3. Component barrier breakage

The barrier of a component is there to protect the component from the outside environment and also to give a way for the component to connect to the circuit. If this barrier is broken, then the component will become exposed to environmental factors such as oxygen and humidity, which can cause the component to age and then fail.

4. Physical problems with materials

The materials used in a PCB can often encounter problems that will cause the board to fail. During the manufacturing stages, if a layer of the PCB is misaligned it will cause short circuits, open circuits and crossed signal lines. If there are psychical defects with the materials such as fractures, voids and delaminations they will seriously affect the performance of the PCB. Failure can also happen if the materials used are impure.

5. Thermal stress

Stress from heat or humidity is one of the biggest causes of PCB failure, especially if a variation of materials has been used. Different materials have different expansion rates, so when constant thermal stress is applied it can break the solder joint and damage the component. If the wrong copper weight is used, or there are plating issues, this will increase the stress from thermal factors. Even during manufacturing the temperature of the room the PCB was assembled in can affect its performance.

6. Manufacturing and cleanliness

Most failure issues happen after the PCB has been manufactured, but they can happen during as well. The environment of the room where the assembly happened can affect the PCB; for example, humidity can affect the way components and solders act when assembled, so environmental conditions need to be controlled Another common failure is from not keeping PCBs clean during and after manufacture. Dust, hair and even bugs can get into the PCB; therefore precautions need to be taken.

Conclusion

By understanding the common failures that happen in PCBs, you can make certain you avoid these issues and take the right precautionary steps to stop it from happening. Remember that you should always check for trace amounts of leaking chemicals; clean up the PCB after soldering; don’t let a component barrier break; use pure materials with no defects in them; avoid exposing your PCB to too much thermal stress and keep the PCB room and hands clean.

Now you know the six most common failures, you will be able to ensure you don’t fall short to any of these problems, which all lead to major losses for your company if they are not avoided or resolved.

For more information on PCB failures and a comprehensive list of the five most commonly used PCB failure analysis tests, you can download our free eBook “The 5 Most Commonly Used PCB Failure Analysis Tests“.

If you have any queries or questions about the issues covered in this blog, don’t hesitate to contact Wayne, one of our laboratory experts, on 01727 871328.