Process validation in PCB manufacturing is essential to ensure the reliability of electronic products. One of the most common tasks in these validation plans is the detection of tin whiskers, microscopic formations that can cause short circuits and field failures.
In this article, we explore how Nufesa Labs conducts tin whisker detection and analysis in a recent case study.
What are tin whiskers and why are they a problem?
Tin whiskers are filament-like metallic growths that can appear on surfaces coated with pure tin. Although they usually range from a few micrometers to several millimeters in length, their presence is dangerous as they can cause electrical short circuits and critical failures in electronic devices. Their formation is associated with mechanical stress in tin coatings, making them a recurring issue in industries such as aerospace, automotive, and telecommunications.
Our process for tin whisker detection
At Nufesa Labs, we follow a structured procedure for identifying and analyzing tin whiskers as part of our validation plans.
1. Initial optical inspection
The first step in our analysis is stereo microscopy inspection. This method allows us to detect initial suspect formations on the PCB surface. In this image, an area of interest is shown with possible tin whisker structures.
2. Confirmation and Measurement Using Electron Microscopy and EDX
To confirm the nature of these formations and obtain precise length measurements, we use a scanning electron microscope (SEM). Additionally, with the energy dispersive X-ray (EDX) detector, we conduct an elemental analysis to verify the material composition.
Here we can see a tin whisker found on a resistor is analyzed through an elemental mapping technique, demonstrating that the formation is pure tin.
Validation plans at Nufesa Labs
Beyond tin whisker analysis, Nufesa Labs provides comprehensive validation plans to ensure that products meet quality and reliability standards.
One key method we employ is Surface Insulation Resistance (SIR) testing, which measures electrical resistance between conductors on a PCB under controlled environmental conditions. This helps assess the material’s ability to prevent electrochemical migration, which could lead to long-term failures.
We use climate chambers to expose products to specific temperature and pressure environments, simulating extreme conditions to evaluate their durability and performance.
Conclusion
The analysis of tin whiskers is a critical step in PCB manufacturing validation, allowing manufacturers to detect potential failures before products reach the market. At Nufesa Labs, we offer a full-service validation process, utilizing advanced methods like optical microscopy, SEM/EDX, and SIR testing, ensuring reliability and compliance with the highest industry standards.
If your company needs a detailed validation analysis or a tin whisker study for your PCBAs, feel free to contact us. We provide precision, reliability, and tailored solutions for your needs.