The influence of packaging materials on RF performance

At frequencies beyond 1 GHz, every component of the IC package contributes to the RF performance, whether required or not. In this work, we study the effects of packaging materials namely, the substrate and the globtop/underfill material on RF performance. We have measured interconnects on two area-array CSPs, the ball grid array and the polymer stud grid array using IMEC’s MCM-D technology. The measurements on the package interconnect show that the losses in the package substrate material account for about 50% of the total losses at 1.8 GHz and this drops to less than 20% at 5.2 GHz. The losses due to impedance mismatch dominate the losses especially below 10 GHz and considerable improvement in performance cannot be obtained by using an improved/expensive substrate. The other study is about the influence of globtop/underfill materials on wirebonds (through 3D EM simulations) as well as on standard 50 Ω MCM-D transmission lines (through experiments). While a higher value of dielectric constant of the globtop/underfill material is better on wirebonds, the influence of loss tangent is felt only above values of 0.1. The influence of seven different globtop/undefill materials on 50 Ω transmission lines has been used to extract their dielectric constant and loss tangent values at 30 GHz. These results are very valuable since one can hardly find the properties of globtop/underfill materials beyond 1 GHz.     

Statistical evaluation of the effect of the mold temperature on the strength of glass containers

Using methods of mathematical statistics (cluster, dispersion, and correlation analyses), the impact strength of three types of glass containers (bottles and jars) was analyzed. Three temperature regions in which molding results in very different values of the strength of the articles are revealed. The boundaries of the molding temperature regions are critical regardless of the type of article molded and are probably only determined by the chemical composition of the glass melt. The preferred mold temperature range is 480–550°C. The results of the study are interpreted based on an analysis of the features of molding glass at different temperatures. __________ Translated from Steklo i Keramika, No. 2, pp. 3–7, February, 2007.     

Production of WC–15Co Ultrafine-Grained Hard Alloy from Powder Obtained by the Electroerosive Dispersion of VK15 Alloy Wastes in Water

Russian Journal of Non-Ferrous Metals - In this paper we study the possibility of producing a WC–15Co ultrafine-grained hard alloy (HA) from a powder obtained by the electroerosive dispersion...     

Droplet formation by squeezing in a microfluidic cross-junction

In microfluidics, flow focusing is widely used to produce water-in-oil droplets in microchannels at high frequency. We here report an experimental study of droplet formation in a microfluidic cross-junction with a minimum number of geometrical parameters. We mostly focus on the squeezing regime, which is composed of two distinct steps: filling and pinching. The duration of each step (and corresponding volumes of each liquid phase) is analyzed. They vary according to both water and oil flow rates. These variations provide several insights about the fluid flows in both phases. We propose several scaling laws to relate the droplet volume and frequency to the flow rate of both phases. We also discuss the influence of surfactant and channel compliance on droplet formation.     

Functionalized polyglycidol-CuCl-complexes as catalysts in the oxidative coupling reaction of terminal acetylenes

Summary Novel hyperbranched amino-terminated polyglycidoles have been synthesized and tested as macromolecular ligands in the oxidative coupling reaction of phenylacetylene. Amino-terminated polyglycidoles-CuCl complexes showed to be more effective catalysts than the reference monomeric tertiary amines-CuCl ones, but less effective than the most efficient N,N,N'N'-tetramethylethylenediamine-(TMDA) CuCl complex. The difference in performance of monomeric and hyperbranched ligands is probably due to two factors. The first one is better complexation abilities and the second is the local increase of reagent concentration. Received: 28 April 2001/Revised version: 29 August 2001/Accepted: 5 September 2001     

Femtosecond laser modification of an array of vertically aligned carbon nanotubes intercalated with Fe phase nanoparticles

Femtosecond lasers (FSL) are playing an increasingly important role in materials research, characterization, and modification. Due to an extremely short pulse width, interactions of FSL irradiation with solid surfaces attract special interest, and a number of unusual phenomena resulted in the formation of new materials are expected. Here, we report on a new nanostructure observed after the interaction of FSL irradiation with arrays of vertically aligned carbon nanotubes (CNTs) intercalated with iron phase catalyst nanoparticles. It was revealed that the FSL laser ablation transforms the topmost layer of CNT array into iron phase nanospheres (40 to 680 nm in diameter) located at the tip of the CNT bundles of conical shape. Besides, the smaller nanospheres (10 to 30 nm in diameter) are found to be beaded at the sides of these bundles. Some of the larger nanospheres are encapsulated into carbon shells, which sometime are found to contain CNTs. The mechanism of creation of such nanostructures is proposed.     

Observations of infrared bands of asymmetrical ozone isotopologues 16O16O18O and 16O18O18O

Infrared spectra (0.003 cm(-1) resolution) of 16O16O18O and 16O18O18O ozone isotopologues have been recorded and analyzed in the range 600-5000 cm(-1). Several thousand rovibrational lines belonging to 32 absorption bands have been measured and assigned. An accurate determination of band centers through the rovibrational analysis has been done, 12 bands being observed for the first time to our knowledge. In addition to atmospheric retrieval applications, these results are also useful for a validation of potential energy surfaces and for the study of isotope effects in dynamic processes of ozone.