WHISFUSE

Lead free component terminations and solder finishes are widely available in the industry and are used in almost all COTS EEE parts (COTS: Commercial Off The Shelf / EEE: Electrical, Electronic and Electro-Mechanical). Due to the increasing demand for these materials and finishes in space flight equipment and instruments, this investigation has been required to assess the potential risks associated with pure or high percentage tin (Sn), which is known to have the potential to grow tin whiskers.

However, this activity has not focused on understanding the growth mechanisms of tin whiskers. Rather, the main aim has been to determinate if the vacuum environment has any effect on tin whisker growth, and to identify if there is an increased risk of short circuits in space flight electronics during a mission. Vacuum testing, simulating the space environment, has been the baseline to evaluate if the vacuum environment can slow or prevent the fusing of tin whiskers.

Thus, the WHISFUSE project has had two main technical objectives:

• To determine if vacuum influences the likelihood and speed of tin whiskers growing.
• To determine the characteristics and current carrying capacity of tin whiskers in vacuum compared to normal, ambient atmosphere.

For both objectives, comparisons with ambient conditions have been used to establish a baseline, from which any differences have been declared and assessed. To accomplish these objectives, an intensive work plan has been required, involving a multidisciplinary technical team composed of three different organizations: CIDETEC (Spain), BME (Budapest) and Łukasiewicz-IMiF (Poland).

CIDETEC’S role in the project:

CIDETEC Surface Engineering coordinated the project and led two of the work packages. During the project, the company carried out the electrodeposition of Sn, analyzed whisker growth, and performed the corresponding characterization in order to establish a relationship between the degree of surface oxidation and the morphology of the whiskers and their electrical properties, as well as between the structure and morphology of the whiskers and the growth conditions.