Equi-Axed Grain Formation in Electrodeposited Sn-Bi

Details Equi-Axed Grain Formation in Electrodeposited Sn-Bi Equi-Axed Grain Formation in Electrodeposited Sn-Bi

Apr 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008jemat..37..490s&link_type=abstract

Journal of Electronic Materials, Volume 37, Issue 4, pp.490-497

Computer Science

3

Sn Whiskers, Electrodeposition, Creep, Solder, Pb-Free

Scientific paper

Sn is widely used as a coating in the electronics industry because it provides excellent solderability, ductility, electrical conductivity, and corrosion resistance. However, Sn whiskers have been observed to grow spontaneously from Sn electrodeposits and are known to cause short circuits in fine-pitched pre-tinned electrical components. We report here a deposition strategy that produces an equi-axed and size-tunable grain structure in Sn-Bi alloys electrodeposited from a commercial bright Sn electrolyte. An equi-axed grain structure should allow a more uniform creep to relieve compressive stress with no localized surface disturbance. The standard potential for Bi is about 0.45 V more positive than Sn. Pulsed deposition can selectively turn on and off the Sn deposition reaction. During the off cycle, a displacement reaction between metallic Sn on the electrode surface and Bi3+ in solution selectively dissolves Sn and deposits Bi, effectively terminating the growth from the previous cycle and forcing the Sn to nucleate a new grain on the Bi-enriched surface. The grain size is tunable by varying the pulsing conditions, and an equi-axed structure can be obtained with as little as 3 at.% Bi. This surface enrichment of Bi by potential modulation is similar to that which occurs naturally in Sn-Pb, and provides an avenue for breaking up the columnar grain structure inherent to pure Sn, thus providing an additional diffusion path for Sn that may prevent whisker growth.

Affiliated with

Also associated with

No associations

Rating

Equi-Axed Grain Formation in Electrodeposited Sn-Bi does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Equi-Axed Grain Formation in Electrodeposited Sn-Bi, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Equi-Axed Grain Formation in Electrodeposited Sn-Bi will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1703480