Atomic Layer Deposition (ALD) to Mitigate Corrosion and Tin Whisker Issues of Printed Circuit Board Assemblies

摘要

Picosun is undertaking a research programme, funded by ESA's European Component Initiative (ECI) Phase 4 and Strategic Initiative (StrIn) programmes, in collaboration with Oy Poltronic Ab and Loughborough University, to evaluate atomic layer deposition (ALD) conformal coatings as a method of mitigating the growth of tin whiskers. The work is investigating the effect of ALD coating process variables on the ability of the coating to prevent whisker growth. Scanning electron microscopy and optical methods have been used to evaluate both the size and distribution of tin whiskers and the coating/whisker interactions. In this paper we will present some of the most interesting initial results from this study. ALD shows promising results as a barrier to whisker growth and our future work will continue on fine-tuning the process and ALD recipes. ALD coatings have been used for a long time as a method of corrosion protection in many industrial and commercial applications. As such they represent an interesting option for the protection of assembled electronic circuit boards and modules when extremely thin, practically massless, re-workable, transparent and inert coatings are needed, especially in certain high-end applications.