Studies on design, fabrication and reliability assessment of embedded passives on a high-density interconnect (HDI) organic substrate using a sequential build-up process

One of the foremost design considerations in microelectronics miniaturization is the use of embedded passives which provide practical solution. In a typical circuit, over 80 percent of the electronic components are passives such as resistors, inductors, and capacitors that could take up to almost 50 percent of the entire printed circuit board area. By integrating passive components within the substrate instead of being on the surface, embedded passives reduce the system real estate, eliminate the need for discrete and assembly, enhance electrical performance and reliability, and potentially reduce the overall cost. Moreover, it is lead free. Even with these advantages, embedded passive technology is at a relatively immature stage and more characterization and optimization are needed for practical applications leading to its commercialization.This paper presents an entire process from design and fabrication to electrical characterization and reliability test of embedded passives on multilayered microvia organic substrate. Two test vehicles focusing on resistors and capacitors have been designed and fabricated. Embedded capacitors in this study are made with polymer/ceramic nanocomposite (BaTiO3) material to take advantage of low processing temperature of polymers and relatively high dielectric constant of ceramics and the values of these capacitors range from 50 pF to 1.5 nF with capacitance per area of approximately 1.5 nF/cm(2). Limited high frequency measurement of these capacitors was performed. Furthermore, reliability assessments of thermal shock and temperature humidity tests based on JEDEC standards were carried out. Resistors used in this work have been of three types: 1) carbon ink based polymer thick film (PTF), 2) resistor foils with known sheet resistivities which are laminated to printed wiring board (PWB) during a sequential build-up (SBU) process and 3) thin-film resistor plating by electroless method. Realization of embedded resistors on conventional board-level high-loss epoxy (similar to 0.015 at 1 GHz) and proposed low-loss BCB dielectric (similar to 0.0008 at > 40 GHz) has been explored in this study. Ni-P and Ni-W-P alloys were plated using conventional electroless plating, and NiCr and NiCrAlSi foils were used for the foil transfer process. For the first time, Benzocyclobutene (BCB) has been proposed as a board level dielectric for advanced System-on-Package (SOP) module primarily due to its attractive low-loss (for RF application) and thin film (for high density wiring) properties.Although embedded passives are more reliable by eliminating solder joint interconnects, they also introduce other concerns such as cracks, delamination and component instability. More layers may be needed to accommodate the embedded passives, and various materials within the substrate may cause significant thermo -mechanical stress due to coefficient of thermal expansion (CTE) mismatch. In this work, numerical models of embedded capacitors have been developed to qualitatively examine the effects of process conditions and electrical performance due to thermo-mechanical deformations.Also, a prototype working product with the board level design including features of embedded resistors and capacitors are underway. Preliminary results of these are presented.

Elucidation of the mechanism of interaction of sheep spleen galectin-1 with splenocytes and its role in cell-matrix adhesion

The binding of a 14 kDa beta-galactoside animal lectin to splenocytes has been studied in detail. The binding data show that there are two classes of binding sites on the cells for the lectin: a high-affinity site with a K-a ranging from 1.1 x 10(6) to 5.1 x 10(5) M-1 and a low affinity binding site with a K-a ranging from 7.7 x 10(4) to 3.4 x 10(4) M-1 The number of receptors per cell for the high- and low-affinity sites is 9 +/- 3 x 10(6) and 2.5 +/- 0.5 x 10(6) respectively. The temperature dependence of the K value yielded the thermodynamic parameters. The energetics of this interaction shows that, although this interaction is essentially enthalpically driven (Delta H - 21 kJ lambda mol(-1)) for the high-affinity sites, there is a very favorable entropy contribution to the free energy of this interaction (-T Delta S - 17.5 Jmol(-1)), suggesting that hydrophobic interaction may also be playing a role in this interaction. Lactose brought about a 20% inhibition of this interaction, whereas the glycoprotein asialofetuin brought about a 75 % inhibition, suggesting that complex carbohydrate structures are involved in the binding of galectin-1 to splenocytes, Galectin-1 also mediated the binding and adhesion of splenocytes to the extracellular matrix glycoprotein laminin, suggesting a role for it in cell-matrix interactions. Copyright (C) 2000 John Wiley & Sons, Ltd.

Novel organic porous solids with channel and layered structures from 1,3,5-triazine-2,4,6-triaminehexaacetic acid and its calcium salt

Single crystals of a symmetrically substituted molecule, 1,3,5-triazine-2,4,6-triaminehexaacetic acid, (TTHA) and its Ca2+ salt have been synthesized, the analysis of which reveals the existence of novel channel type cavities and helical packing organizations in the crystals.

Phase diagram and dielectric studies of binary organic materials

The phase equilibrium studies of organic system, involving resorcinol (R) and p-dimethylaminobenzaldehyde (DMAB), reveal the formation of a 1:1 molecular complex with two eutectics. The heat of mixing, entropy of fusion, roughness parameter, interfacial energy, and the excess thermodynamic functions were calculated based on enthalpy of fusion data determined via differential scanning calorimetric (DSC) method. X-ray powder diffraction studies confirm that the eutectics are not simple mechanical mixture of the components under investigation. The spectroscopic investigations (IR and NMR) suggest the occurrence of hydrogen bonding between the components forming the molecular complex. The dielectric measurements, carried out on hot-pressed addition compound (molecular complex), show higher dielectric constant at 320 K than that of individual components. The microstructural investigations of eutectic and addition compound indicate dendritic and faceted morphological features. (C) 2000 Elsevier Science B.V. All rights reserved.

Effects of electron correlations in conjugated organic molecules and solids

The discrepancies between the non-interacting models and experimental results for conjugated systems is highlighted in this brief review. The interacting model hamiltonians correctly give the forbidden singlet state below the optical gap in polyenes and also explain both the nonvanishing optical gap in polyacetylenes and the vanishing optical gap in symmetric cyanine dyes. The negative spin densities in polyene radicals is also understood in terms of a correlated picture. The role of electron-electron interactions in other strongly correlated systems, such as polydiacetylene and mixed and segregated stack charge transfer solids, are also briefly discussed.

Numerically Exact Study of Polarizabilities and Hyperpolarizabilities of Correlated Conjugated Organic Models

Polarizabilities and Hyperpolarizabilities of conjugated organic chains are calculated using correlated model Hamiltonians. While correlations reduce the Polarizabilities and extend the range of linear response, the Hyperpolarizabilities essentially are unaffected by the same. This explains the apparently large Hyperpolarizabilities of conjugated electronic systems.

A density matrix renormalization group study of low-lying excitations of polythiophene within a Pariser-Parr-Pople model

Symmetrized density-matrix-renormalization-group calculations have been carried out, within Pariser-Parr-Pople Hamiltonian, to explore the nature of the ground and low-lying excited states of long polythiophene oligomers. We have exploited C-2 symmetry and spin parity of the system to obtain excited states of experimental interest, and studied the lowest dipole allowed excited state and lowest dipole forbidden two photon state, for different oligomer sizes. In the long system limit, the dipole allowed excited state always lies below the lowest dipole forbidden two-photon state which implies, by Kasha rule, that polythiophene fluoresces strongly. The lowest triplet state lies below two-photon state as usual in conjugated polymers. We have doped the system with a hole and an electron and obtained the charge excitation gap and the binding energy of the 1(1)B(u)(-) exciton. We have calculated the charge density of the ground, one-photon and two-photon states for the longer system size of 10 thiophene rings to characterize these states. We have studied bond order in these states to get an idea about the equilibrium excited state geometry of the system. We have also studied the charge density distribution of the singly and doubly doped polarons for longer system size, and observe that polythiophenes do not support bipolarons.

A soluble random-matrix model for relaxation in quantum systems

We study the relaxation of a degenerate two-level system interacting with a heat bath, assuming a random-matrix model for the system-bath interaction. For times larger than the duration of a collision and smaller than the Poincaré recurrence time, the survival probability of still finding the system at timet in the same state in which it was prepared att=0 is exactly calculated.

On the hardness and elastic modulus of bulk metallic glass matrix composites

The influences of the amorphous matrix and crystalline dendrite phases on the hardness and elastic moduli of Zr/Ti-based bulk metallic glass matrix composites have been assessed. While the moduli of the composites correspond to those predicted by the rule of mixtures, the hardness of the composites is similar to that of the matrix, suggesting that the plastic flow in the composites under constrained conditions such as indentation is controlled by the flow resistance of the contiguous matrix. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Non-carboxylate based metal-organic frameworks (MOFs) and related aspects

The metal-organic frameworks, in recent years, show a variety of new developments that includes new methods of preparation, post synthesis modifications and novel class of compounds. Though most of the developments happened in the carboxylate based family of compounds, the other related systems are also equally interesting. In this article,we have highlighted some of the developments that have taken place in the family of non-carboxylate metal-organic frameworks. We have also highlighted some of the recent attempts at modifying the surfaces and pores of the MOFs by careful chemical manipulations. (C) 2009 Elsevier Ltd. All rights reserved.

Computing a matrix symmetrizer exactly using modified multiple modulus residue arithmetic

A symmetric solution X satisfying the matrix equation XA = AtX is called a symmetrizer of the matrix A. A general algorithm to compute a matrix symmetrizer is obtained. A new multiple-modulus residue arithmetic called floating-point modular arithmetic is described and implemented on the algorithm to compute an error-free matrix symmetrizer.

PVA-SSA-HPA Mixed-Matrix-Membrane Electrolytes for DMFCs

Stabilized forms of heteropolyacids (HPAs), namely phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), are incorporated into poly (vinyl alcohol) (PVA) cross-linked with sulfosuccinic acid (SSA) to form mixed-matrix membranes for application in direct methanol fuel cells (DMFCs). Bridging SSA between PVA molecules not only strengthens the network but also facilitates proton conduction in HPAs. The mixed-matrix membranes are characterized for their mechanical stability, sorption capability, ion-exchange capacity, and wetting in conjunction with their proton conductivity, methanol permeability, and DMFC performance. Methanol-release kinetics is studied ex situ by volume-localized NMR spectroscopy (employing point-resolved spectroscopy'') with the results clearly demonstrating that the incorporation of certain inorganic fillers in PVA-SSA viz., STA and PTA, retards the methanol-release kinetics under osmotic drag compared to Nafion, although PVA-SSA itself exhibits a still lower methanol permeability. The methanol crossover rate for PVA-SSA-HPA-bridged-mixed-matrix membranes decreases dramatically with increasing current density rendering higher DMFC performance in relation to a DMFC using a pristine PVA-SSA membrane. A peak power density of 150 mW/cm(2) at a load current density of 500 mA/cm(2) is achieved for the DMFC using a PVA-SSA-STA-bridged-mixed-matrix-membrane electrolyte. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3465653] All rights reserved.

In situ surface modification of molybdenum-doped organic-inorganic hybrid TiO2 nanoparticles under hydrothermal conditions and treatment of pharmaceutical effluent

Molybdenum-doped TiO2 organic-inorganic hybrid nanoparticles were synthesized under mild hydrothermal conditions by in situ surface modification using n-butylamine. This was carried out at 150 degrees C at autogeneous pressure over 18 h. n-Butylamine was selected as a surfactant since it produced nanoparticles of the desired size and shape. The products were characterized using powder X-ray diffraction, Fourier transform infrared spectrometry, dynamic light-scattering spectroscopy, UV-Vis spectroscopy and transmission electron microscopy. Chemical oxygen demand was estimated in order to determine the photodegradation efficiency of the molybdenum-doped TiO2 hybrid nanoparticles in the treatment of pharmaceutical effluents. It was found that molybdenum-doped TiO2 hybrid nanoparticles showed higher photocatalytic efficiency than untreated TiO2 nanoparticles.

Partially conserved axial-vector current inS-matrix theory

Mandelstam�s argument that PCAC follows from assigning Lorentz quantum numberM=1 to the massless pion is examined in the context of multiparticle dual resonance model. We construct a factorisable dual model for pions which is formulated operatorially on the harmonic oscillator Fock space along the lines of Neveu-Schwarz model. The model has bothm ? andm ? as arbitrary parameters unconstrained by the duality requirement. Adler self-consistency condition is satisfied if and only if the conditionm?2?m?2=1/2 is imposed, in which case the model reduces to the chiral dual pion model of Neveu and Thorn, and Schwarz. The Lorentz quantum number of the pion in the dual model is shown to beM=0.

A matrix identity and perturbation expressions

An identity expressing formally the diagonal and off-diagonal elements of an inverse of a matrix is deduced employing operator techniques. Several well-known perturbation expressions for the self-energy are deduced as special cases. A new approximation and other applications following from the above formalism are briefly indicated through illustrations from a perturbed harmonic oscillator, chemisorption approximations and Kelly's result in the problem of electron correlation.