@inproceedings{8d8b5b03377b4c2b8145e34c343897dd,
title = "Bending fatigue characteristic of Sn-3.5Ag solder bump on Ni-UBM",
abstract = "Bending fatigue behavior of eutectic Sn-3.5Ag solder bump bonded on FR4-PCB was characterized by experimental and finite element method (FEM). To investigate an effect of stress state on bump failure, which had not been weighed in conventional Coffin-Manson model of Nf= K·Δεp-1-2, 'fatigue frequency variable' and 'bump viscoplasticity' were included in analysis procedure. As experimental results, with increasing fatigue cycles from 3,000 to 10,000, bond strength decreased from 98.9% to 76.5%, and from 97.5% to 67.1% at the fatigue frequencies of 2.5Hz and 5.0Hz, respectively. Stress state could be critical components to determine fatigue life, which should be combined in Coffin-Manson criteria. FEM calculation showed that higher bending frequency led to higher normal stress development at the solder and IMC interface, but smaller plastic strain in bump. However, bending fatigue experiment revealed discrepant results from that of Coffin-Manson criteria. Higher bending frequency, which was predicted to give rise to smaller Δεp at solder, showed dramatic bond deterioration of solder bump on UBM (under bump metallurgy). This was confirmed experimentally through SEM (scanning electron microscopy) observation as cracks were found at the solder bump and UBM interfacial IMC, Ni3Sn4, in case of the higher bending frequency.",
keywords = "Bending fatigue, Coffin-Manson model, Microstructure, Sn-3.5Ag solder, Stress state",
author = "Kang, {K. I.} and Jung, {J. P.} and Bang, {W. H.} and Park, {J. H.} and Oh, {K. H.}",
year = "2008",
doi = "10.4028/www.scientific.net/msf.580-582.177",
language = "English",
series = "Materials Science Forum",
publisher = "Trans Tech Publications Ltd.",
pages = "177--182",
editor = "Lee, {Chang Hee} and Jong-Bong Lee and Jong-Bong Lee and Dong-Hwan Park and Suck-Joo Na",
booktitle = "Materials Science Forum - Advanced Welding and Micro Joining/Packaging for the 21st Century - Selected peer reviewed papers from the International Welding/Joining Conference-Korea 2007, IWJC 2007",
address = "Switzerland",
note = "International Welding/Joining Conference-Korea 2007, IWJC 2007 ; Conference date: 10-05-2007 Through 12-05-2007",
}