Suppressing tin whisker growth in lead-free solders and platings
AssigneeSavannah River Nuclear Solutions, LLC
InventorsElizabeth N Hoffman, Poh-Sang Lam
Life of this patent
Estimating the term…
Abstract
A process of irradiation Sn containing Pb-free solder to mitigate whisker formation and growth thereon is provided. The use of gamma radiation such as cobalt-60 has been applied to a substrate of Sn on copper has been found to change the morphology of the crystalline whisker growth to a more truncated hillock pattern. The change in morphology greatly reduces the tendency of whiskers to contribute to electrical short-circuits being used as a Pb-free solder system on a copper substrate.
Claims7
A process of treating a lead-free, Sn-based solder or plating comprising the steps of:
- subjecting said solder or plating to an effective amount of gamma radiation so as to form an altered crystalline formation on a surface of the Sn so as to prevent the formation of whiskers.
A process of treating Sn containing lead-free solder or plating on a copper substrate comprising the steps of exposing the Sn solder or plating to a gamma radiation source for a time interval sufficient for the formation of a Rouaite coating on a surface of the Sn, wherein said Rouaite is resistant to the formation of whiskers.
A process of treating a lead free, Sn-based solder or plating on a substrate comprising the steps of:
- subjecting said solder or plating to an effective amount of gamma radiation so as to form a coating of metal nitrate upon a surface of the Sn solder or plating.
Dependencies are inferred from the claim text.