A flip chip having solder bumps and an integrated flux and underfill, as well as method for making such a device, is described. The resulting device is well suited for a simple one-step application to a printed circuit board, thereby simpliflying flip chip manufacturing processes which heretofore have required separatate fluxing and underfilling steps.

Flip chip with integrated flux and underfill

Factors affecting CO2 absorption efficiency in packed column: A review

Rate-based calculations for trayed and packed columns offer process engineers a more rigorous and reliable basis for assessing column performance than the traditional equilibrium-stage approach, especially for multicomponent separations. Although the mathematics, thermodynamics, and transport-related physics upon which nonequilibrium separations theory is founded are generally true, it is also true that rate-based simulations today suffer from a serious weakness—they are ultimately tied to underlying equipment performance correlations with questionable predictive capability. In the case of packed columns operated countercurrently, correlations are required for the mass-transfer coefficients, kx and ky, for the specific area participating in mass transfer, am, for the two-phase pressure drop, (Δp/Z)2ϕ, and for the flood capacity of the column. In particular, it is generally well known that packing mass-transfer correlations available in the public domain are unreliable when they are applied to chemical systems and column operating conditions outside of those used to develop the correlations in the first place. For that reason, we undertake the development of dependable, dimensionally consistent, correlating expressions for the mass-transfer-related quantities kx, ky, and am for metal Pall rings, metal IMTP, sheet metal structured packings of the MELLAPAK type, and metal gauze structured packings in the X configuration, using a new data fitting procedure. We demonstrate the superior performance of these correlations for a wide range of chemical systems and column operating conditions, including distillations as well as acid gas capture with amines. Further, we show that these new correlations lead to predictions for the relative interfacial area participating in mass transfer that can be greatly in excess of the geometrical surface area of the packing itself. © 2011 American Institute of Chemical Engineers AIChE J, 2012

New mass-transfer correlations for packed towers

Sulfur compounds such as sulfur oxides (SOx) are generated and emitted from operations in the petroleum industry which have negative effects on the environment. This study gives a critical and detailed introduction to the control and treatment of sulfur co...

Control and treatment of sulfur compounds specially sulfur oxides (SOx) emissions from the petroleum industry: A review

Detailed modelling of a flue-gas desulfurisation plant

The effective area a e of three types of highly effective packings such as Raschig Super-Ring, IMTP and Ralu-Flow made from stainless steel and from plastic with nominal size from 20 to 70 mm, are investigated using the Danckwerts method with absorption of CO 2 in NaOH by pseudo-first-order fast chemical reaction. The liquid superficial velocity L varied between 5 and 200 m 3 /(m 2 h). The comparison of the obtained data shows the following: Among all investigated packings at comparable values of the specific area and the liquid superficial velocities, the metal Raschig Super-Rings (RSR) have the highest effective area. They have also the lowest pressure drop versus effective area, at the same gas velocity. At comparable values of the specific area and the liquid superficial velocities the effective areas of the plastic Ralu-Flow and plastic RSR are practically the same, but the first of them have lower pressure drop versus effective area, at the same gas velocity. As it is to be expected, all metal packings have greater effective area than all plastic ones with the same specific area. That means among all investigated 14 packings, the metal RSR have the greatest effective area.

Comparison of the effective area of some highly effective packings

The liquid radial spreading coefficient of packings for absorption and rectification columns is necessary to determine the packing height which ensures uniform liquid distribution over the column cross section. The existing calculation methods can be used theoretically only when this coefficient is independent of the liquid superficial velocity, which is often not the case. A tracer method free from this limitation is developed and tested. The spreading coefficients for different sizes of modern, highly effective packings (Raschig Super-Ring, Ralu-Flow, and impulse metal tower packing) are determined. Practically, in the range of the experimental error, the spreading coefficients of these packings are independent of the liquid superficial velocity. For such packings the tracer method is expected to give the same results as the existing single jet method. Some differences between the results of these two methods are discussed and an explanation is proposed.

Determination of Liquid Radial Spreading Coefficients of Some Highly Effective Packings

A novel design of a honeycomb packing with turbulizers in the region of the boundary layer (Turbo-Pack) has been designed and investigated. The presence of turbulizers is shown to decrease the pressure drop per mass transfer unit in cases of both gas-film and liquid-film controlled mass transfer. A comparison of the best packings known so far from the literature shows that, regarding such an important parameter as pressure drop per mass transfer unit, the novel packing has significant advantages. On the basis of experimental data obtained by studying 11 different packing designs in liquids of various viscosity, equations for determining the performance characteristics of the novel packing are obtained. In the first part of this work, the data on packing design, pressure drop and loading point are presented.

Performance characteristics of a packing with boundary layer turbulizers

Among the known types of packings, arranged packings with vertical walls have the lowest pressure drop for one transfer unit at comparable free volume as well as the highest efficiency at a given pressure drop. Reliable equations are derived for pressure drop determination in industrial apparatuses filled with this kind of packing. The pressure drop is presented as a sum of two terms-pressure drop (in the vertical channels) of the packing rows themselves and local pressure drop of the boundary sections between the rows. The experimental data for dry packing pressure drop, available in the literature and newly obtained, are described by new equation with mean deviation of 9.3%. Equations for determination of wetted packings pressure drop up to the loading point and above it are obtained, too. The proposed equations can also be used to determine the loading point.

Pressure drop of arranged packings with vertical walls

The performance of a column packing depends besides physical properties of the systems to be separated and the operational conditions mainly on the basic shape, the thickness of the material and the main dimensions of the packing elements. These magnitudes of construction govern the specific area including the void fraction of the packing and therefore its efficiency, pressure drop and capacity. It is reported about constructive measures for optization of a packing geometry

N. Kolev

Papers

Comparison of the effective area of some highly effective packings

Determination of Liquid Radial Spreading Coefficients of Some Highly Effective Packings

Performance characteristics of a packing with boundary layer turbulizers

Pressure drop of arranged packings with vertical walls

On the optimal form of stacks in packed columns