Driving force of tin whisker growth · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Driving force of tin whisker growth
Plain
Thin tin coatings in electronics spontaneously grow hair-like metal filaments that can short circuits, sometimes years after manufacture. What stress or process pushes the atoms into the whisker is not established.
Precise · changed · core
Revision 1: Electroplated Sn films on Cu grow single-crystal whiskers of diameter about 1e-4 to 1e-3 cm and length up to about 1 cm. Determine the driving force (compressive stress from Cu6Sn5 intermetallic growth relieved by grain-boundary diffusion under a surface oxide, recrystallization of grains with oblique boundaries, or other contributions) and predict which grains grow whiskers, the incubation time and the growth rate versus stress and temperature. An answer is a model verified on films with controlled stress and microstructure.
Revision 2: Electroplated Sn films on Cu grow single-crystal whiskers of diameter about $10^{-4}$ to $10^{-3}$ cm and length up to about 1 cm. Determine the driving force (compressive stress from $\mathrm{Cu_6Sn_5}$ intermetallic growth relieved by grain-boundary diffusion under a surface oxide, recrystallization of grains with oblique boundaries, or other contributions) and predict which grains grow whiskers, the incubation time and the growth rate versus stress and temperature. An answer is a model verified on films with controlled stress and microstructure.
Settled by
Whisker incubation and growth measured on films with independently imposed stress and characterized grain structure, matching a diffusion-and-stress model.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
open
Status note
(empty)
Posed since
(empty)

Decisions