Transcript 下載/瀏覽

L.C. Tsaoa,*, S.Y. Changb
a Department
of Materials Engineering, National Pingtung University of Science and Technology, 91201 Neipu, Pingtung, Taiwan
of Mechanical Engineering, National Yunlin University of Science and Technology, 64002 Touliu, Yunlin, Taiwan
b Department
學
生：陳立偉
指導教授：林克默
日
期：2009.12.25
1
 1. Introduction
 2. Experimental
 3. Results and discussion
 4. Conclusions
2
1. Introduction
 Mavoori et al. developed a Pb37Sn based solder with 10 nm
Al2O3 and 5 nm TiO2 reinforcement particles and reported
significant improvements in creep resistance and mechanical
properties.
 Lin et al. studied the Sn37Pb composite solders with the
reinforcement of TiO2 and copper nanopowders. Their results
showed profound effects on the thermal characteristics of
solder solidification and reduction of the grain size.
 In the present study, a lead-free Sn3.5Ag0.25Cu (SAC)
composite solder mixed with TiO2 nanopowders has been
further developed. Their thermal properties, microstructure and
mechanical behavior have been studied.
3
2. Experimental
tin、silver and copper (99.99 pct)
in a vacuum furnace at 650℃ for 2.5
Sn3.5Ag0.25Cu (wt.%)
0.25, 0.5, and 1
(wt.%) of TiO2
nopowders
mechanically dispersing
FE-SEM image showing the TiO2
nanopowders used in this study.
in a vacuum furnace at
650℃ for 2.5
mold to form square
ingots of 8*10*20 mm
DSC
SEM(OM)
XRD
Tensile
tests
Microhardness
4
3.Results and discussion
DSC curves of the SAC solder and the SAC
composite solder containing TiO2 nanopowders
5
SEM micrographs of as-cast solders: (a) SAC, (b) SAC-0.25TiO2 , (c) SAC-0.5TiO2 and
(d) SAC-1TiO2
6
X-ray diffraction spectrum of the SAC solders with the addition of
different amounts of TiO2 nanopowders.
7
Tensile stress–strain curves of the lead-free SAC composite
solders at room temperature.
8
 This indicates that if the TiO2 nanopowders addition is
increased, the composite solder can be improved due to
the presence of TiO2 nanopowders as reinforcement. This
could be attributed to:
(1) pinning grain boundaries and thus impeding sliding of
the grain boundaries.
(2) the increase of dislocation densities and obstacles to
restrict the motion of dislocation.
(3) the hardening mechanism of the matrix and TiO2
nanopowders.
9
4. Conclusions
 Lead-free SAC composite solders reinforced with 0.25, 0.5,
and 1 (wt.%) of TiO2 nanopowders were successfully blended.
The solidus temperatures of the lead-free SAC composite
solders was very similar to that of lead-free SAC solder.
 Microstructural investigation revealed that TiO2 nanopowder
addition influenced both the grain size and morphology of
Ag3Sn.
 Mechanical test results revealed that the microhardness, YS,
and UTS of the composite solder increasing with increasing
addition of TiO2 nanopowders. However, the ductility of the
composite solders was found to decrease because of greater
amounts of microporosity observed at the Ag3Sn network grain
boundary.
10
Thank you for
your attention
11