Teddington, UK, April 11 -- With the forthcoming ban on the use of lead, there is a need to develop a test method to measure the internal stresses in the coatings of electronic components, based on the XRD technique. These internal stresses are a potential cause of whisker growth in lead-free finishes.

According to a recently released report, XRD measurement correlates to measured compressive residual stress on coatings with whisker growth. Three coatings with high compressive residual stress also exhibited whiskering. However, the coatings evaluated were all at least twice as thick as penetration depth of the XRD measurement system, and the measured compressive residual stress values did not start to increase until after the formation of tin whiskers. However, the XRD method did provide some correlation between residual stress in the coatings and the extent of whisker growth.

The findings were released as a part of the National Physical Laboratory's Phase 2 Studio Project to understand tin whiskers.

 

For more information contact Dr. Chris Hunt: Lchris.hunt@npl.co.uk.

 

 

• Prev
• Next