Minimizing whisker growth in tin electrodeposits

Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Depositing predominantly single metal coating

Reexamination Certificate

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C205S302000, C106S001250

Reexamination Certificate

active

06860981

ABSTRACT:
The present invention relates to a method for reducing tin whisker formation in tin deposits by plating on an underlying metal tin deposits which are predominantly in a predetermined crystal orientation that essentially matches that of the underlying metal in order to inhibit tin whisker growth. The most preferred crystal orientation is one that is the same as that of the underlying metal. The deposit preferably contains at least 95% tin and optionally at least one alloying element of silver, bismuth, copper or zinc in an amount of 5% or less. Advantageously, the tin deposits are provided during electroplating from a specially formulated plating solution.

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A. Egli, et al, “Where Crystal Planes Meet—Contribution to the Understanding of the Tin Whisker Growth Process”, Proceedings of IPC Annual Meeting, Nov. 2002, New Orleans, LA, USA.
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