Title: Evaluation of lead-free solder reliability under vibration at elevated temperature

Authors: Yong-Ho Ko; Sehoon Yoo; Chang-Woo Lee

Addresses: Micro-Joining Center, Korea Institute of Industrial Technology, 7-47, Songdo-Dong, Yeonsu-Gu, Incheon 406-840, South Korea ' Micro-Joining Center, Korea Institute of Industrial Technology, 7-47, Songdo-Dong, Yeonsu-Gu, Incheon 406-840, South Korea ' Micro-Joining Center, Korea Institute of Industrial Technology, 7-47, Songdo-Dong, Yeonsu-Gu, Incheon 406-840, South Korea

Abstract: Lead-free solders have been recently applied to automotive electronics under harsh, high temperature environments. In this study, the high temperature vibration reliability was evaluated for Sn-3.5Ag and Sn-0.7Cu solders. The lead-free solder balls with diameters of 450 µm were mounted on ENIG-finished Cu pads of a BGA test chip. The solder-ball-mounted BGA test chips were then assembled on an OSP finished Cu pads of a daisy-chained PCB. The vibration test was performed with the acceleration of 27.8 m/s², a frequency of 10∼1,000 Hz, and test temperatures of 85 and 150°C. The reliability of solder joint was determined by electrical resistance and shear strength. The resistance increased gradually and shear strength were decreased as the test time increased. After a 120-hour test, the resistance of Sn-3.5Ag increased by 71% for the 150°C test condition. In addition, shear strength degradation was observed in Sn-3.5Ag solders under high temperature. The Sn-0.7Cu solder was much more stable as compared with the Sn-3.5Ag solders.

Keywords: lead-free soldering; vibration reliability; ENIG; OSP; electrical resistance; shear strength; solder reliability; high temperature; tin; copper; silver; BGA; ball grid arrays.

DOI: 10.1504/IJMSI.2014.064773

International Journal of Materials and Structural Integrity, 2014 Vol.8 No.1/2/3, pp.53 - 61

Published online: 21 Oct 2014 *

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