PCB failure analysis is a systematic method to determine the root cause of the failure. The steps involved may use techniques and tools to amplify the factors that cause the problem and provide input for the PCB designer to remediate measures.

PCB designers should pay attention to failure analysis methods. It is very important to make PCB failure analysis an indispensable part of the product life cycle to ensure that all problems are effectively solved.

It is wrong to assume that after the design is converted into a physical product and deployed in the field, the PCB designer's job is over. If so, the skills of PCB designers are really tested when consumers use electronic products.

Regardless of your proficiency in design theory, it is only a matter of time before the first major test is conducted in the form of a failed product in the field. It gives rise to the perception bubble that you have covered all aspects of design, and it will not fail.

But the reality is that PCB designers are just people, and mistakes are part of their work. However, when the product fails, the PCB designer is not the only responsible party. Variables such as PCB manufacturing, assembly and installation may affect the function of the production unit.

PCB designers must be prepared for the fact that failures occur.

As a PCB designer, it helps to understand how to perform failure analysis methods when such events occur. The results of the failure analysis method help determine what went wrong in PCB production. It provides an opportunity to improve the design.

Common failure analysis methods

In some cases, there may be obvious signs leading to the root cause of the failure. In other cases, there is no indication that the failure of the PCB was caused by visual inspection. This requires a more professional failure analysis method usually performed by a failure analyst.

The following are some common PCB failure analysis methods.

1. Optical microscope
High magnification microscopes with magnifications up to 1000 times are often used to identify potential manufacturing and assembly problems. This method is widely used due to its efficiency and accuracy. If the analyst needs a deeper understanding of the mold structure, a scanning electron microscope with a magnification of up to 100,000 times can be used.

2. X-ray fluorescence examination

The use of X-rays is useful for identifying elements that evade visual or microscopic inspection. For example, only X-ray tools can be used to verify the solder joints of BGA components. The same goes for the integrity of PCB traces and vias, as X-ray scans will reveal any cracks that cause intermittent problems.

3. Cross-sectional analysis

Considered to be a more destructive technique, the cross-section or micro-section method involves cutting out the problematic PCB area. Carry out operations such as etching and polishing to gradually expose the measured area. Cross-sectional analysis can enable failure analysts to better understand solder joints and metal thickness.

4. Contamination test

Whether it is the chemical solution of the PCB manufacturing and assembly process. Some of these chemicals, if not thoroughly cleaned, may degrade PCBs over time. Contamination testing involves detecting chemical elements that may not have escaped from the cleaning process.