Pb-Free and High Reliability Solders

The many and varied solder applications require an analytical system than can meet the precision and versatility needed to accurately measure the elemental make up of solders. The international push towards lead-free (Pb-free) solders in place of traditional tin-lead (Sn-Pb) solder alloys has added complexities to the supply chain. As there is no single Pb-free substitute for Sn-Pb alloys, various Pb-free solders have emerged with a range of properties and requirements. Even as their adoption continues to grow, the industry has yet to paint a full picture of their performance – one of the most well-known drawbacks of Pb-free solders is the risk of electrical shorts from the development of tin whiskers. Due to this, many 'high reliability” applications, such as aerospace and military electronics, continue to use Sn-Pb.

To ensure the correct solder is used for an application, companies at every step of the supply chain are developing or have developed policies to reduce the risk of mistaking solders. The most proven method to eliminate damage is to directly and carefully screen all components. One of the fastest and most reliable testing methods commonly used to screen soldered components is x-ray fluorescence (XRF), which has the additional advantage of being non-destructive.

Monitoring plans using XRF exist for both ensuring compliance with directives aiming to be Pb-free as well as meeting a minimum Pb content to mitigate whiskering. For example, the European Restriction of Hazardous Substances (RoHS) directive limits Pb to 1000ppm (0.1%), while industry standards for high reliability applications call for a minimum Pb content of 3% in order to greatly reduces the risk of tin whiskers. XRF instruments can be calibrated to precisely and accurately determine compositions to these thresholds.
To learn more about how you can use x-ray fluorescence to screen your soldered components, read our latest applications note!

To learn more about how you can use x-ray fluorescence to screen your soldered components, read our latest Application Bulletin.