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.     

Photosensitivity of thin-film ZnO/CdS/Cu(In, Ga)Se2 solar cells

The photoelectric properties of thin-film ZnO/CdS/Cu(In,Ga)Se₂ solar cells were studied by polarization photoactive absorption spectroscopy. It was shown that the thin-film solar cells have a high efficiency relative to the intensity of unpolarized radiation in the photon energy range from 1.2 to 2.5 eV. The induced photopleochroism coefficient P _I increases with the angle of incidence of the incident radiation as P _I ∼θ ² and at 70° it reaches 17–20% with photon energy 1.3 eV. Oscillations of the photopleochroism were also observed. These results are discussed taking into account the antireflection effect. The results obtained by us make it possible to use such solar cells as wide-band photosensors for linearly polarized radiation and for monitoring the production of high-efficiency, thin-film solar cells based on ternary semiconductors. Fiz. Tekh. Poluprovodn. 31, 806–810 (July 1997)     

Heme-dependent and heme-independent nitrite reduction by lactic acid bacteria results in different N-containing products

Seventy strains of lactic acid bacteria were investigated for nitrite reductase activity. Two types of this activity were detected. Type I was found in Lactobacillus plantarum, L. pentosus and Pediococcus pentosaceus. This activity is heme-dependent with ammonia as the sole product. Type II mechanism is heme-independent and reduces nitrite to NO and N₂O.     

An ionene with spirane structure (spiroionene)

The secondary diamine 1,3,5,7-tetrahydro[1,2c:4,5c'] benzodipyrrole (3) and 1,2,4,5-tetrabromomethylbenzene (1) form a polymeric ionene with spirane structure through a repetitive alkylation reaction. The structure of the product could be proven by¹³C-NMR spectroscopy by comparison with suitable reference compounds. Solutions in aqueous methanol exhibit a typical polyelectrolyte effect. Variation of the counterions produces sufficient solubility in organic solvents. From the crystal structure of a similar model compound one can conclude that the synthesized polymer has a rod-like shape.     

Feststoffbildung durch Kristallisation und Fällung

Formation of solids by crystallization and precipitation. Formation of solids from solutions can take place by crystallization or precipitation. The principal factor is the relationship between solubility and supersaturation. In crystallization, the solubility of the crystallising substance is so high that the formation of solids occurs largely in the metastable zone in the immediate vicinity of the solubility limits. Crystal growth and nucleation are functions of supersaturation. If a high supersaturation is required at low substance-specific growth rates for an adequate crystal growth, high nucleation rates and hence small crystals will result. On this basis, the authors present information for the specific design of crystallization processes. In contrast, the solubility of the precipitated product must be very low for precipitation. Direct crystal formation is possible only for substance systems of high solubility. As a rule, however, the precipitated substance is so insoluble that solids are formed via amorphous intermediates. The results of a large number of experiments show the influence of various parameters of the precipitation process on the filtrability of the precipitated product.     

Hydrodynamic constraints on evolution of chemically mediated interactions between aquatic organisms in unidirectional flows

Two hydrodynamic habitats can be defined in unidirectional flow: (1) A boundary where molecular diffusion dominates is found within roughly 1 mm of solid substrates. The actual thickness of this diffusion boundary is a function of current velocity and topography of the substrates. (2) A zone of turbulent flow is present outside the diffusion boundary where chemicals are rapidly diluted and transported downstream. The mode of chemically mediated interaction between organisms in streams is constrained differently depending on which of these two habitats they occupy. Within a diffusion boundary, reciprocal interaction between small organisms is possible because mixing is low, diffusion flux high, and organisms share the same water. Outside a diffusion boundary, in unidirectional flow, organisms unable to move effectively against flow are only chemically influenced by upstream organisms and can only influence downstream organisms. Organisms that are able to move upstream can interact reciprocally with other organisms, even if one or both organisms are found primarily in areas of turbulent mixing.     

Hemoglobin-fortified biscuits: bioavailability and its effect on iron nutriture in school children

School-age children in Chile received 30 g of wheat-flour biscuits daily through a National School Lunch Program. To improve iron nutrition, these biscuits were fortified with 6% of a bovine hemoglobin concentrate. Hemoglobin iron bioavailability, measured with a double isotope technique, showed that heme-iron absorption in fortified biscuits was high (19.7%). In a pilot field trial, a cohort of 215 school-children received fortified biscuits (30 g) daily during two school periods, and their iron nutrition status was compared with that of children who received non-fortified biscuits (n = 212). Acceptability of both types of biscuits was excellent. Initially, both groups had comparably good iron nutrition. The fortified children presented higher mean ferritin values at the end of the first and second school periods. Good iron stores (serum ferritin greater than or equal to 20 micrograms/lt) were present in 92% and 79% of the fortified and control subjects, respectively (P less than 0.004). The high-iron bioavailability, the good organoleptic characteristics and the biological effect on iron nutriture make this product an appealing alternative to combat iron deficiency.     

Effect of light, solvents and commercial enzymes on the solubility and stability of sesquiterpene lactones from chicory roots

Summary The solubility of lactucin, 8-deoxylactucin and lactucopicrin, all sesquiterpene lactones of chicory roots, was determined as a function of pH (pH 1–10) in the presence and absence of polysaccharides. The stability of the sesquiterpene lactones, when dissolved in water, decreased under influence of daylight as a function of pH. Enzymatic hydrolysis of lactucopicrin by commercial enzyme preparations, used for liquefaction of chicory roots into lactucin and p-hydroxyphenylacetic acid, was not found.

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Einfluß von Licht, Lösungsmittel und Handelsenzymen auf die Löslichkeit und Stabilität der Sesquiterpen-Lactone von Zichorienwurzeln

Zusammenfassung Die Stabilität von LaCA Bussurnctucin, 8-Deoxylactucin und Lactucopicrin (alles SesquiterpenLactone der Zichorienwurzel) wurde in Abhängigkeit vom pH-Wert beim Aufbewahren im Licht studiert. Es konnte ein Abbau dieser Verbindungen nachgewiesen werden. Die Löslichkeit dieser drei Verbindungen wurde in Abhängigkeit vom pH-Wert mit und ohne Polysaccharide bestimmt. Es wurde keine Hydrolyse des Lactucopicrins unter der Einwirkung von kommerziellen Enzymen, die bei der Verflüssigung von Zichorienwurzeln verwendet werden, gefunden.

     

Filler cement: The effect of the secondary component on the hydration of Portland cement: Part 2: Fine hydraulic binders

In Part 1 of this paper, it was shown that enhanced hydration was achieved by blending a fine non-hydraulic filler into an ordinary Portland cement. This enhancement was considered to be a particle size effect and associated with the presence of fine particles of filler which provided the additional nucleation sites. The filler, rutile, had a variable cement equivalence and reached a maximum value of 0.9kg/kg after hydration had proceeded for three days. In this second part, the same Portland cement was blended seperately with latent hydraulic binders (two pulverized fuel ashes and a ground granulated blastfurnace slag, a Lurgi slag and a volatilized silica). The apparent overall reactivity of these binders was seen to have two components, the first being the particle size effect with its influence on the hydration of the Portland cement and the second the inherent hydraulicity of the secondary material.     

德国迪林根ROGESA钢铁公司2号烧结机EFA(R)烟气处理系统及其运转情况

多年来,环境保护一直是烧结行业的一个重要课题.由于政府部门提出了更加严格的要求,烧结厂废气的进一步净化已经变得很有必要.一套新开发的、工业化的EFA(曳流吸收塔)烟气处理系统于2006年年中在ROGESA钢铁公司投入运行.本文就该系统的工艺流程、特点及运行情况作一介绍.