Abstract: Gold coated silica core nanoparticles have an optical
response dictated by the plasmon resonance. The wavelength at
which the resonance occurs depends on the core and shell sizes,
allowing nanoshells to be tailored for particular applications. The
purposes of this study was to synthesize and use different
concentration of gold nanoshells as exogenous material for skin
tissue soldering and also to examine the effect of laser soldering
parameters on the properties of repaired skin. Two mixtures of
albumin solder and different concentration of gold nanoshells were
prepared. A full thickness incision of 2×20 mm2 was made on the
surface and after addition of mixtures it was irradiated by an 810nm
diode laser at different power densities. The changes of tensile
strength σt due to temperature rise, number of scan (Ns), and scan
velocity (Vs) were investigated. The results showed at constant laser
power density (I), σt of repaired incisions increases by increasing the
concentration of gold nanoshells, Ns and decreasing Vs. It is therefore
important to consider the trade off between the scan velocity and the
surface temperature for achieving an optimum operating condition. In
our case this corresponds to σt =1610 gr/cm2 at I~ 60 Wcm-2, T ~
65ºC, Ns =10 and Vs=0.2mms-1.
Abstract: Void formation in underfill is considered as failure
in flip chip manufacturing process. Void formation possibly caused
by several factors such as poor soldering and flux residue during
die attach process, void entrapment due moisture contamination,
dispense pattern process and setting up the curing process. This
paper presents the comparison of single step and two steps curing
profile towards the void and black dots formation in underfill for
Hi-CTE Flip Chip Ceramic Ball Grid Array Package (FC-CBGA).
Statistic analysis was conducted to analyze how different factors
such as wafer lot, sawing technique, underfill fillet height and
curing profile recipe were affected the formation of voids and
black dots. A C-Mode Scanning Aqoustic Microscopy (C-SAM)
was used to scan the total count of voids and black dots. It was
shown that the 2 steps curing profile provided solution for void
elimination and black dots in underfill after curing process.
Abstract: Adhesively bonded joints are preferred over the
conventional methods of joining such as riveting, welding, bolting
and soldering. Some of the main advantages of adhesive joints
compared to conventional joints are the ability to join dissimilar
materials and damage-sensitive materials, better stress distribution,
weight reduction, fabrication of complicated shapes, excellent
thermal and insulation properties, vibration response and enhanced
damping control, smoother aerodynamic surfaces and an
improvement in corrosion and fatigue resistance. This paper presents
the behavior of adhesively bonded joints subjected to combined
thermal loadings, using the numerical methods. The joint
configuration considers aluminum as central adherend with six
different outer adherends including aluminum, steel, titanium, boronepoxy,
unidirectional graphite-epoxy and cross-ply graphite-epoxy
and epoxy-based adhesives. Free expansion of the joint in x
direction was permitted and stresses in adhesive layer and interfaces
calculated for different adherends.
Abstract: Standard packaging and interconnection technologies
of power devices have difficulties meeting the increasing thermal
demands of new application fields of power electronics devices.
Main restrictions are the decreasing reliability of bond-wires and
solder layers with increasing junction temperature. In the last few
years intensive efforts have been invested in developing new
packaging and interconnection solutions which may open a path to
future application of power devices. In this paper, the main failure
mechanisms of power devices are described and principle of new
packaging and interconnection concepts and their power cycling
reliability are presented.
Abstract: Laser soldering is based on applying some soldering material (albumin) onto the approximated edges of the cut and heating the solder (and the underlying tissues) by a laser beam. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. Gold nanoshells are new materials which have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes, allowing nanoshells to be tailored for particular applications. The purposes of this study was use combination of ICG and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2×20 mm2 was made on the surface and after addition of mixtures it was irradiated by an 810nm diode laser at different power densities. The changes of tensile strength σt due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σt of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns and decreasing Vs. It is therefore important to consider the tradeoff between the scan velocity and the surface temperature for achieving an optimum operating condition. In our case this corresponds to σt =1800 gr/cm2 at I~ 47 Wcm-2, T ~ 85ºC, Ns =10 and Vs=0.3mms-1.