Vibration-induced fatigue failures in bonding wires used in stackedchip modules
Leidecker, H.
Hull, S.
Goddard Space Flight Center, Greenbelt, MD;
This paper appears in: Multichip Modules and High Density Packaging, 1998. Proceedings. 1998 International Conference on
Publication Date: 15-17 Apr 1998
On page(s): 308-313
Meeting Date: 04/15/1998 - 04/17/1998
Location: Denver, CO, USA
ISBN: 0-7803-4850-8
References Cited: 7
INSPEC Accession Number: 6046774
Digital Object Identifier: 10.1109/ICMCM.1998.670799
Current Version Published: 2002-08-06
Abstract
An instrument recently constructed at Goddard Space Flight Center
involved stacked chip memory modules with about six thousand 1 mil gold
wires, each between 4.6 mm and 6.1 mm long. Four bond wires fractured
during the final box-level random vibration test, which had spectral
power to 850 Hz. We determined that these wires have fundamental
resonant frequencies in the range from 1.4 kHz to 2.3 kHz, with quality
factors up to 300, when the bonds at each end are rigid. However, a
nearly severed top bond decreases the lead's fundamental frequency into
the range from 600 Hz to 750 Hz. The lowered mode is strongly excited by
the box-level vibration test, leading to fatigue-fracture of that
already weakened bond during the several minutes of the vibration test.
However, such a lowered mode would not be excited by previous shock and
vibration tests, since these happened to have no spectral power in the
region from 600 Hz to 750 Hz. In separate tests, an unfractured 1 mil
gold wire was still intact after 12 days (1.4 billion oscillations) at
1.4 kHz at a root-strain of 0.2%, while several (deliberately) nearly
fractured wires failed after less than a minute (less than 41,000
oscillations) at 680 Hz at the same drive stress
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