DocumentCode :
628505
Title :
Plastic deformation effect on Sn whisker growth in electroplated Sn and Sn-Ag solders
Author :
Kang, Sung Kil ; Jaewon Chang ; Jae-Ho Lee ; Keun-Soo Kim ; Hyuck Mo Lee
Author_Institution :
IBM T.J. Watson Res. Center, Yorktown Heights, NY, USA
fYear :
2013
fDate :
28-31 May 2013
Firstpage :
1018
Lastpage :
1023
Abstract :
Sn whiskers are becoming a serious reliability problem in microelectronics where Pb-free solder technology is being implemented with pure Sn or Sn-rich alloys. Numerous investigations have been performed to understand the whisker growth mechanisms and thereby to mitigate Sn whisker growth. Among many Sn whisker mitigation strategies, minor alloying additions to Sn have been found to be quite effective. One challenge in evaluating Sn whisker growth is a time-consuming aging test, such as 4000 h testing condition recommended by the JEDEC-JESD201A standard. In this study, several commercial Sn and Sn-Ag baths of low whisker formulations are evaluated. The effects of plating variables and aging conditions on Sn whisker growth are investigated with matte Sn, matte Sn-Ag, and bright Sn-Ag electroplated on a Cu/Ni/Si substrate. The layer thickness and current density are the major plating variables studied. Two different storage conditions are applied; an ambient condition (30°C/dry air), and a high temperature/humidity condition (55°C/85%RH). In addition, the effect of plastic deformation on Sn whisker growth is investigated as an acceleration method for Sn whisker testing. Microhardness indentation technique is applied to electroplated Sn and Sn-Ag samples to plastically deform them before T/H testing. Each sample is examined by SEM at a regular time interval up to 4000 h. Various morphologies of Sn whiskers are observed and their growth statistics are analyzed in terms of plating conditions, plastic deformation and T/H testing conditions. Plastic deformation is found to significantly accelerate Sn whisker growth both in pure Sn and Sn-Ag samples. The method of plastic deformation can be employed to shorten the time-consuming Sn whisker growth testing.
Keywords :
ageing; current density; electroplating; indentation; integrated circuit reliability; microhardness; plastic deformation; silver alloys; solders; tin; tin alloys; Cu-Ni-Si; JEDEC-JESD201A standard; Si; Sn; SnAg; acceleration method; aging conditions; current density; electroplated layer thickness; electroplated solders; microelectronics; microhardness indentation technique; plastic deformation effect; plating variables; reliability; solder technology; time-consuming aging test; whisker growth; whisker testing; Current density; Humidity; Plastics; Substrates; Testing; Tin;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Electronic Components and Technology Conference (ECTC), 2013 IEEE 63rd
Conference_Location :
Las Vegas, NV
ISSN :
0569-5503
Print_ISBN :
978-1-4799-0233-0
Type :
conf
DOI :
10.1109/ECTC.2013.6575697
Filename :
6575697
Link To Document :
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