11 / 13
allied
academies
Page 40
Notes:
Journal of Materials Science and Nanotechnology | Volume 3
October 07-08, 2019 | Frankfurt, Germany
Materials Science and Engineering
3
rd
International Conference on
Mater Sci Nanotechnol, Volume 3
Mechanical property of nano porous sintered silver: Toward reliability estimation
Keisuke Wakamoto
1
, Yo Mochizuki
2
, Takukazu Otsuka
1
, Ken Nakahara
1
and
Takahiro Namazu
2
1
ROHM Co Ltd, Japan
2
Aichi Institute of Technology, Japan
S
intered silver as a die attach material has attracted much
research attensiton especially in the power electronics
field, owing to its high heat dissipation capability. Many
electrical systems comprisesmany die-attach parts electrically
connecting semiconductor dies, and the coefficient of
thermal expantion (CTE) of these parts differs variously. This
inevtibaly leads to repeated mechanical stresses under heat
cycle environments, deteriorating the die-attach materials.
Thus the mechanical property of sintered silver plays a critical
role to estimate the reliability of systems.
In this regard, the porosity inevitably embedded in sinterd
silver is an important research issue. Other studies performed
tensile tests with thick sintered silver films (over 100μm
thick), however the thickness is much larger than that of die-
attach layer thickness (~50μm). Thus, we cannot eliminate
the possibility of differnt failure mode observation, and/or of
underestimating overly the role of porosity. In this study, the
authers prepare sintered silver films and bulk silver thin films
with thickness of apploximately 8-10 μm to focus on how
the size of the pores therein affects the mechanical property
of the films. The sintered films are fabricated from 5MPa to
60MPa pressure by using silver nanoparticles. The porosity (p)
of the films ranges from 5% to 25%. This p is determined by
scanning electron microscopy cross-sectional images of the
films. For the sintered films, the stress-strain behaviors show
no conventional ductile plateau disappears, and the breaking
strain, and ultimate tensile strength negatively correlates with
p. The tensile fatigue test is performed for the sintered silver
with p=5% and the bulk silver. The fatigue lifetime of the silver
films is shorter than that of the bulk silver one. The breaking
point is larger for the sintered film, but the fatigue lifetime
does not reflect this property, determined by the porosity.
Speaker Biography
Keisuke Wakamoto has completed his Master degree at the age of 25
years from Kyoto University, Japan. He is the research engineer of Rohm
company Modules R &D group, Japan. His publication was published on
May 21 from Japanese Journal of Applied physics 58, SDDL08 (2019).
e:
keisuke.wakamoto@dsn.rohm.co.jp