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991.
The tensile strengths of bulk solders and joint couples of Sn-3.5Ag-0.5Cu, Sn-3.5Ag-0.07Ni, and Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge
solders and the shear strengths of ball grid array (BGA) specimens, solder-ball-attached Cu/Ni/Au metallized substrates were
investigated. The tensile strength of the bulk is degraded by thermal aging. The Ni-containing solder exhibits lower tensile
strength than Sn-3.5Ag-0.5Cu after thermal aging. However, the Ni-containing solder joints show greater tensile strength than
the Cu/Sn-3.5Ag-0.5Cu/Cu joint. Fracture of the solder joint occurs between the intermetallic compound (IMC) and the solder.
The shear strength and fracture mechanism of BGA specimens are the same regardless of solder composition. 相似文献
992.
Naren Noolu Nikhil Murdeshwar Kevin Ely John Lippold William BaeslackIII 《Journal of Electronic Materials》2004,33(4):340-352
Gold-aluminum ball bonds were thermally exposed at constant elevated temperatures, and the resultant phase transformations
studied in detail. The as-bonded microstructure of a Au-Al ball bond essentially consisted of a reaction zone (termed “alloyed
zone” (AZ) in the as-bonded condition) between the Au bump and the bonded Al metallization. It is the growth of the reaction
zone between the Au bump and the bonded Al metallization and also the nonbonded Al metallization during thermal exposure that
gave rise to the various phase transformations. Au4Al, Au8Al3, and Au2Al are the predominant phases that grew across the ball bond until the bonded Al metallization is available to take part in
the interdiffusion reactions. After the complete consumption of the bonded Al metallization, the Au-Al phases reverse transformed
resulting in the formation of the Au4Al phase in the entire reaction zone across the ball bond (RZ-A). The lateral interdiffusion reactions resulted in the nucleation
and the growth of all of the Au-Al phases given by the phase diagram. Kidson’s analysis and Tu et al.’s treatment were extended
to a five-phase binary system to explain the phase transformations in thermally exposed Au-Al ball bonds. It is possible for
all of the Au-Al phases to grow across a ball bond uninhibited as long as the bonded metallization is available. However,
the supply limitation of the bonded metallization gives rise to reverse transformations where Al-rich phases transform to
Au-rich phases and eventually result in the formation of the Au4Al phase in the entire RZ-A. If infinite time is allowed, Au4Al would dissolve; the extent of which is dependent on the solubility of Al in Au. No supply of Au lateral to the bond causes
the reverse transformation of the Au4Al phase, giving rise to the lateral growth of the remaining Au-Al phases. If infinite time is allowed, the lateral phase
transformations would result in the formation of a phase that is dependant on the relative proportion of Au and Al present
in the nonbonded metallization (NBM) and Au4Al below the void line. Hence, the presence of a phase in a particular location of a ball bond is dependent on the time and
temperature of thermal exposure. 相似文献
993.
Michael B. Pursley Harlan B. Russell Jeffrey S. Wysocarski 《International Journal of Wireless Information Networks》2004,11(3):147-159
The use of adaptive-transmission protocols in wireless, store-and-forward, packet communication networks may result in large differences in the energy requirements of the alternative paths that are available to the routing protocol. Routing metrics can provide quantitative measures of the quality and energy efficiency of the paths from the source to the destination. Such measures are required if the routing protocol is to take advantage of the potential energy savings that are made possible by an adaptive-transmission protocol. An energy-efficient protocol suite for routing and adaptive transmission in frequency-hop wireless networks is described and evaluated, several routing metrics are compared, and tradeoffs among energy efficiency, delay, and packet success probability are investigated. 相似文献
994.
Kurt P. Judmann 《e & i Elektrotechnik und Informationstechnik》2004,121(5):160-161
Ohne Zusammenfassung 相似文献
995.
Yongtaek Hong Zhiqi He Nancy S. Lennhoff David A. Banach Jerzy Kanicki 《Journal of Electronic Materials》2004,33(4):312-320
In this paper, we describe the properties of flexible plastic substrates with a transparent conducting electrode (TCE), which
are important for organic light-emitting devices (OLEDs). Specifically, we have evaluated the TCE electrical resistivity,
surface roughness, electrode patterning, optical transmission, and the substrate water vapor/oxygen transmission. We have
studied the effect of ultraviolet (UV)-ozone treatment on the TCE surface by using contact angle measurements and x-ray photoelectron
spectroscopy (XPS). A decrease in the advancing contact angle by 30–40° and an increase of oxygen content on the TCE surface
by 10 at.% were observed after the UV-ozone treatment. These changes facilitate the polymer adhesion to the TCE surface and
increase the TCE surface work function, respectively. A sheet resistance of 12–13 Ω/□, an optical transmission greater than
80% over the visible range, and a surface roughness of 1.4–2.2-nm RMS over 50×50 μm2 have been obtained for the plastic substrates. These properties are adequate for OLED applications based on United States
Display Consortium specifications. Finally, we have found that a combination of hydrogenated amorphous silicon-nitride and
silicon-oxide layers deposited on one side of the substrate at low-temperature reduces the water vapor and oxygen transmission
rates (TRs) to less than 10−5 g/cm2-day-atm and about 10−7 cc/cm2-day-atm, respectively. 相似文献
996.
WangFeixue OuGang ZhuangZhaowen 《电子科学学刊(英文版)》2004,21(1):33-36
A kind of novel binary phase code named sidelobe suppression code is proposed in this paper.It is defined to be the code whose corresponding optimal sidelobe suppression filter outputs the minimum sidelobes.It is shown that there do exist sidelobe suppression codes better than the conventional optimal codes-Barker codes.For example,the sidelobe suppression code of length 11 with filter of length 39 has better sidelobe level up to 17dB than that of Barker code with the same code length and filter length. 相似文献
997.
Annealing effects of a high-quality ZnTe substrate 总被引:1,自引:0,他引:1
Kenji Yoshino Minoru Yoneta Kenzo Ohmori Hiroshi Saito Masakazu Ohishi Takayuki Yabe 《Journal of Electronic Materials》2004,33(6):579-582
The sharp photoluminescence (PL) and optical-reflection spectra in the bandedge region of the high-quality nondoped ZnTe substrate
(100) were observed at 4.2 K. Free exciton, associated with lower and upper polaritons (EXL and EXU) at 2.382 eV and 2.381 eV, respectively, were clearly observed. This meant that this substrate was high quality. The intensity
of a bound exciton peak (2.375 eV), which is caused by a Zn vacancy, of a neutral acceptor decreased with an increase of the
Zn vapor pressures. 相似文献
998.
The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat
transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal
pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable
and the method is applicable to combustion and heat transfer of the marine supercharged boiler. 相似文献
999.
Thermal Radiative Properties of Xonotlite Insulation Material 总被引:1,自引:0,他引:1
X inxin ZHANG Gaosheng WEI Fan YU Department of Thermal Engineering University of Science & Technology Beijing Beijing China Professor 《热科学学报(英文版)》2005,14(3):281-283,253
Introduction Xonotlite-type calcium silicate (6CaO?6SiO2?H2O) is synthesized porous insulation material by hydrothermal processing with quartz powder and limestone as the raw material (with CaO/ SiO2≈1:1). Compared with fire- retardant fibre, xonotlite has more excellent insulating performance, such as low thermal conductivity, environment friendly, high intension, and wide applying temperature range, which has been emphasized in recent years by many scholars and widely used in many indu… 相似文献
1000.
Anton O. Belyakov Alexey A. Davydov Vladimir M. Veliov 《Journal of Dynamical and Control Systems》2015,21(3):475-494
The paper contributes to the topic of optimal utilization of spatially distributed renewable resources. Namely, a problem of “sustainable” optimal cyclic exploitation of a renewable resource with logistic law of recovery is investigated. The resource is distributed on a circle and is collected by a single harvester moving along the circle. The recovering and harvesting rates are position dependent, and the latter depends also on the velocity of the harvester, which is considered as a control. The existence of an optimal solution is proved, as well as necessary optimality conditions for the velocity of the harvester. On this base, a numerical approach is proposed, and some qualitative properties of the optimal solutions are established. The results are illustrated by numerical examples, which reveal some economically meaningful features of the optimal harvesting. 相似文献