The fabrication of a complete PCB assembly requires an array of machines and materials, which include:
- Screen printers
- Pick-and-place systems
- Reflow ovens
- Automated optical inspection
- Solder paste
- Different components
Some machines have automated features that perform checks at various points, and operators perform visual inspections before, during or immediately after the completion of a task.
Nonetheless, many PCBs will fail the final test. When a problem does occur, it is important to perform an effective electronics failure analysis in order to obtain clear and precise details about the source of the problem — and to ensure that it does not happen again.
The technician must conduct a root cause analysis to identify the cause of the failure — not the symptoms — and take corrective action to fix the issue. Failure analysis also provides invaluable feedback to design engineers on how to:
- Correct minor faults that might have gone unnoticed during the initial design
- Improve the product
Any company that produces electronic hardware strives to achieve zero-defect production. To realize this objective, manufacturers must have the capability to perform some level of printed circuit board failure analysis. Some companies rely on outside expertise for more complex problems.
For many high-reliability systems — such as oil rigs, space satellites, implantable medical devices and other systems — failures can be devastating. In the case of consumer products, a single failure mode, which can replicate thousands or millions of times, can have a huge impact on the bottom line.
Electronic device failure analysis provides a systematic process to help organizations investigate and understand why an electronic part failed. Depending on the nature of the failure, an effective investigation can identify the failure mode, mechanism and elements, such as stresses inducing the failure and other issues.
For example, solder joint defects make up a large percentage of PCB failures. Manufacturers can discover the root cause of the defective joints — such as a lack of solder paste, a gap between the PCB pad and component lead, or poor reflow profile — and then implement preventative measures. To eliminate future failures, possible solutions may be to avoid solder paste contamination or ensure the correct aspect ratio. The methods used in the analysis depend on the severity of the failure and the type of issue. They can range from simple electrical measurements to the evaluation of sample cross-sections under a microscope.
An effective and efficient root cause analysis ensures that manufacturers can initiate the necessary corrective action to prevent reoccurrence of the problem. Failure analysis processes evaluate the reliability of a component product under operation and determine how to improve the product.