Abstract:

As the current trends toward miniaturization take hold, proper cleanliness levels become more difficult to achieve. In addition, effective cleaning requirements may not be in place. The smaller spacing between conductors also yields a larger electric field, which in conjunction with insufficient cleaning can lead to dendritic growth. This paper investigates the effects of chloride contamination and electric field on the migration behavior of hot air solder level (HASL) plated FR-4 printed circuit boards. It was found that chloride contamination level and electric field influence which failure mechanism is occurring, electrochemical migration or electrolytic corrosion. This study concludes that current industry specifications for cleanliness may be inadequate for the next generation of electronic assemblies.

Key words: electrochemical migration, dendritic growth, electric field, contamination

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