Development of ultra-fined grain structure by cryorolling process of sac305 and sn100c solder alloy
Loading...
Date
2019-07
Authors
Wan Asilah Binti Wan Azalan
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The new lead-free solder alloys, which has been proposed as the alternative solder
to overcome the environmental concern of lead-based solder need to meet a variety of
good trait properties especially for higher reliability solder, as requested by automotive
and electronic industries. Therefore, the present work investigated the microstructure,
wettability and mechanical properties of cryorolled SAC305 and SN100C solder alloys.
Prior to cryorolling, the solder alloys were dipped in liquid nitrogen for cryogenic
treatment (CT) with different dipping time . Based on SEM equipped with EDX analysis,
two type of intermetallic compound were present for SAC305, Ag3Sn and Cu6Sn5, while
for SN100C, there was present of only Cu6Sn5 intermetallic compound. Phases and
crystallite size of all the solder samples were analysed by XRD and sample with cryogenic
treatment prior to rolling exhibited a smaller crystallite size with 38.22 nm for SAC305
and 32.82 nm for SN100C. Sample of SAC305 solder alloy with dipping in liquid
nitrogen prior to rolling enhanced the Vickers microhardness by 13.6% compared to ascast sample due to grain refinement of about 46.5%. Besides, CT prior to rolling give
very good wetting angle which is lower than 30˚ for both solders. Shear strength test for
mechanical analysis showed that an improvement of about 7.3% and 23.1% for SAC305
and SN100C solder sample respectively after dipping in liquid nitrogen for 30 minutes
compared to sample without dipping in liquid nitrogen. As a conclusion, solder alloy
which were dipped into liquid nitrogen prior to rolling seems to improve the mechanical
properties, wettability and lead to grain refinement of solders.