Maureen E. Williams, C E. Johnson, Kil-Won Moon, Gery R. Stafford, C A. Handwerker, William J. Boettinger
The probability of whisker growth on as-deposited tin (Sn) electrodeposits has been measured as a function of copper (Cu superscript2+) addition to a commercial bright methanesulfonate electrolyte. Two substrate materials were used: free standing 250 um thick pyrophosphate Cu and 40 nm thick fine grain Cu evaporated on silicon (Si)(100) wafer. Deposits 3 um thick and 3 cm (superscript 2) in area with average composition between 0% and 1.6% mass fraction Cu were produced from Cu (superscript 2+) electrolyte concentrations between 0 and 25 x 10 (superscript 3) mol/L respectively at 60 mA/cm (superscrip 2) in a rotating disk geometry. Whisker defects were not observed on any of the pure Sn deposits regardless of substrate, nor were they present on Sn-Cu films deposited on the evaporated Cu on Si(100) substrate. However, whiskers started to grow after only 2 days on the Sn-Cu films deposited on the pyrophosphate Cu substrates. Detailed measurements over 12% of the deposit areas after one year of room temperature storage show a defect density of less than 5 /mm (superscript -2) for compositions below 0.25% mass fraction Cu, but a density of approximately 40 /mm(superscript 2) for compositions above 0.7% mass fraction Cu. The effect of Cu content and substrate material on the defect density is discussed.
SUR/FIN 2002 | | | The American Electroplaters and Surface Finishers Society, Inc.
June 24-27, 2002
Cu concentration, defect density, electrodeposit, electrolyte concentrations, Sn whiskers, substrate
, Johnson, C.
, Moon, K.
, Stafford, G.
, Handwerker, C.
and Boettinger, W.
Whisker Formation on Electroplated Sn-Cu, SUR/FIN 2002 | | | The American Electroplaters and Surface Finishers Society, Inc.
(Accessed December 4, 2023)