With the electronics packaging industry shifting increasingly to three-dimensional packaging, microbumps have been adopted as the vertical interconnects between chips. Consequently, solder volumes have decreased dramatically, and the solder thickness has reduced to a range between a few and 10 microns. The solder volume of a microbump is approximately two orders of magnitude smaller than a traditional flip-chip joint. In contrast, the thickness of the under-bump metallization (UBM) remains almost the same as that in flip-chip solder joints. Therefore, many issues concerning materials and reliability of microbumps arise. This article reviews the challenges related to microbump materials for vertical interconnects, including transformation of solder joints into intermetallic (IMC) joints, necking or voiding induced by side wetting/diffusion on the circumference of the UBM, formation of porous Cu3Sn IMCs, early electromigration failures caused by specific orientations of Sn grains, and precipitation of plate-like Ag3Sn IMCs. An alternative way of fabricating vertical interconnects using direct Cu-to-Cu bonding is also discussed.

We present a simple and quick procedure for the one-pot synthesis of manganese oxides under a basic solvothermal condition in the presence of cationic surfactants acting as the template in a 2-butanol/water solution. Three-dimensional spinel-type MnO2 microspheres composed of small nanoparticles have been fabricated for the first time using our method. Their corresponding electrochemical performances in the applications of supercapacitor electrodes exhibit a good specific capacitance (SC) value of ∼190 F/g at 0.5 A/g and excellent SC retention and Coulombic efficiency of ∼100% and ∼95% after 1000 charge/discharge cycles at 1 A/g, respectively. This suggests its potential applications in energy storage devices. Further, we demonstrate that this solvothermal technique enables the morphological tuning of manganese oxides in various forms such as schists, rods, fibers, and nanoparticles. This work describes a rapid and low-cost technique to fabricate novel architectures of manganese oxides having the desired crystal phase, which will highly benefit various supercapacitor applications.

Boron-doped, single (∼54 nm) or double (∼21 + 54 nm) Si1−xGex layers were epitaxially grown on 300-mm-diameter p−-Si(100) device wafers with 20 nm technology node design features, by ultrahigh vacuum chemical vapor deposition. The Si1−xGex/Si wafers were annealed in the temperature range of 950–1050 °C for 60 s to investigate the effect of annealing on possible changes of Ge content and Si stress near the Si1−xGex/Si interface. High spectral resolution, micro-Raman spectroscopy was used as a nondestructive characterization technique with five excitation wavelengths of 363.8, 441.6, 457.9, 488.0, and 514.5 nm. Ge diffusion and generation of compressive stress at the Si1−xGex/Si interface were measured on all annealed wafers. Ge diffusion and the accumulation of compressive Si stress after annealing showed significantly different behaviors between single- and double-layer Si1−xGex/Si wafers. Raman characterization results were compared with secondary ion mass spectroscopy and high-resolution x-ray diffraction results.

A total of six amplified fragment length polymorphism (AFLP) primer combinations were used to detect genetic variation of pooled DNA in a sample of 12 chicken breeds indigenous to China, and AFLP DNA fingerprinting of each chicken breed was constructed. Polymorphic bands, specific bands and genetic similarity coefficients of 12 chicken breeds were calculated from AFLP data. A total of 279 polymorphic bands were generated by the six primer combinations, giving, on average, 46.5 polymorphic markers detected per primer combination. Nine specific bands were produced in the pooled DNA of Jiuyuan black and Dongxiang black chickens. However, one specific band was produced in the pooled DNA of Wenchang and Xingyi bantam chickens. An unweighted-pair-group method using average linkages (UPGMA) cluster analysis revealed that the 12 chicken breeds could be divided into three groups. Genetic similarity coefficients and the UPGMA tree of the 12 chicken breeds were consistent with their breeding history as well as their geographical distribution. Based on AFLP DNA fingerprinting, genetic diversity, genetic relationship and identification of chicken breeds can be analysed.

This paper presents new findings regarding the effects of precursor drop size and concentration on product particle size and morphology in ultrasonic spray pyrolysis. Large precursor drops (diameter >30 μm) generated by ultrasonic atomization at 120kHz yielded particles with holes. Precursor drops 6-9 μm in diameter, generated by an ultrasonic nebulizer at 1.65MHz and 23.5W electric drive power, yielded uniform spherical particles 150nm in diameter under proper control of heating rate and precursor concentration. Moreover, air-assisted ultrasonic spray pyrolysis at 120kHz and 2.3W yielded spherical particles of which nearly half were smaller than those produced by the ultrasonic spray pyrolysis of the 6-9 μm precursor drops, despite the much larger precursor drop sizes (28 μm peak diameter versus 7 μm mean diameter). These particles are much smaller than those predicted by the conventional one particle per drop mechanism, suggesting that a vapor condensation mechanism may also be involved in spray pyrolysis. It may be concluded that through this new mechanism air-assisted ultrasonic spray pyrolysis can become a viable process for mass production of nanoparticles.

A nonlinear and time dependent finite element analysis was performed on two surface mounted electronic devices subjected to thermal cycling. Constitutive equations accounting for both plasticity and creep for 37Pb/63Sn and 90Pb/10Sn solders were assumed and implemented in a finite element program ABAQUS with the aid of a user subroutine. The FE results of 37Pb/63Sn solder joints were in reasonably good agreement with the experimental data by Hall [19]. In the case of 9OPb/1OSn solder in a multilayered transistor stack, the FE results showed the existence of strong peel stress near the free edge of the joint, in addition to the anticipated shear stress. The effect of such peel stress on the crack initiation and growth as a result of thermal cycling was discussed, together with the singular behavior of both shear and peel stresses near the free edge.

For modern management and full resource sharing among libraries and scientific departments both in Chinese and worldwide observatories, we established the computer system of library management and information retrieval during the period 1984-1987.

The system is composed of ten component sub-systems:

• 1. Book ordering system. This system can produce orders for books and periodicals, balance accounts, produce statistics as well as claims for outstanding book orders.

• 2. Book cataloguing system. This system can catalogue books under certain rules while appending new records of books to the databases. It can also produce catalogue cards and produce written reports about the new books.

• 3. Book retrieval system has the ability to search for a specific book in several ways.

• 4. Book lending or circulation system. This system is a complete circulation system; including book lending, renewals, waiting lists, and recall of borrowed books.

• 5. Periodical management system. This system is in charge of processing of periodicals and magazines in the library, including cataloguing, management, and lending.

• 6. Scientific information retrieval system. One can retrieve scientific information by keywords or in many other ways.

• 7. Internal material booking system. It can make orders of internal materials, claims for materials outstanding and make exchanges with other observatories and institutions both in or outside the country.

• 8. Internal material management system. It can do the work that is analogous to that done with books and periodicals.

• 9. Information relationship system. It handles exchanges of information between institutions. Computer system of library management ... at Shaanxl 183

• 10. Scientific information network management system. It manages affairs within a certain information network.