Malgorzata Langer

Influence of carbon coatings origin on the properties important for biomedical application

Abstract The purpose of the present study was to investigate the properties of a carbon layer depending of the origin of applied methods. Quasiamorphous carbon coatings prepared by ion beam methane decomposition by RF dense plasma and vacuum pulsed arc deposition were applied to stainless steel implants used in surgery. The studies of carbon films as coatings for implants in surgery were aimed on the investigations of biological resistance of implants, histopathological investigations using laboratory animals, tests of corrosion resistance, measurements of mechanical properties and a breakdown test in Tyrod solution. The comparison of the properties of the coating produced by these methods shows very good biotolerance and biocompatibility of all of the coatings. They are not corroded in physiological fluids. From the other side they have different properties, especially electrical and optical, and are not influenced on medical applications. The obtained results prove that the implants coated by all the methods mentioned are a very good material for medical use.

The corrosion tests of amorphous carbon coatings deposited by r.f. dense plasma onto steel with different chromium contents

In the paper the results of experimental studies concerning characterization of amorphous carbon layers obtained by a new method of r.f. dense plasma CVD onto steel with different chromium contents are presented. Thin, amorphous carbon layers, deposited onto these substrates, are the subject of structural and physical investigations. This refers also to the system of carbon layer-steel substrate correlated with a microstructure of the layer, and to the determination of specifications resulting from the model for optimization of the synthesis and applicability of a new system as medical implants. Amorphous carbon coatings produced by the dense r.f. CH4 plasma method from steel AISI-316L used in medicine were investigated to determine their suitability as biomaterials.

The numerical approach to analysis of microchannel cooling systems

The paper deals with microchannel cooling where water is the cooling liquid. ANSYS software and CFDRC-ACE one were used to analyse the flows and the origin of large amount of heat that can be overtaken from the chip when microchannels are applied. The concept of microscale heat transfer coefficient is discussed. The phenomena taking place in microchannel flows are simulated and some conclusions are introduced to explain the results met in many references but still unexplained. In contrast to existing, standard methods, the new approach describes the local phenomena and is used in the further investigation of the cooling microstructure. An effect of its geometry on the total overtaken heat flux is analysed with respect to optimal conditions as well as to technological restrictions.

Verification of Nanocrystalline Diamond Films’ Quality

The films discussed in this paper are deposited by r.f. dense plasma CVD. Amorphous carbon, DLC, and nanocrystalline diamond layers are very interesting candidates for active and passive electronic and optoelectronic applications. It is well known that diamond films possess semiconductor properties. (Though, as by now it is possible to obtain doping in special conditions). Because of their large energy gap, chemical inertness and temperature stability they are very perspective. The principal condition to apply them is not only to gain high quality but also to assure the stability of the obtained properties.

Simulation of parasitic interconnect capacitance for present and future ICs

The performance of modern integrated circuits is often determined by interconnect wiring requirements. Moreover, continuous scaling of VLSI circuits leads to an increase in the influence of interconnects on system performance. It is desired therefore, to calculate accurately its parasitic components, particularly wiring capacitance. In order to recognize which one from the most popular empirical approaches gives the evaluation of the total capacitance that suits to the real capacitance of the interconnect line, the numerical simulations based on the numerical solving of Maxwell equations have been employed.

Heat diffusion – searching for the accurate modeling

The authors study three approaches which allow to model the steady state heat conduction in a 2D multiphase composite. The subject under investigating is the thermal conductivity of a c-BN composite thick film with possible inclusions of air bubbles. To define the thermal conductivity we have utilized (i) a commercial program ANSYS, for which a random structure has been externally generated, (ii) a cellular automata (CA) based model and (iii) a modified cellular automata based model where we have taken into account a thermal contact resistance between adjacent grains of c-BN.

Analytical Solutions of the Diffusive Heat Equation as the Application for Multi-cellular Device Modeling – A Numerical Aspect

This work concerns the thermal analysis of solid state devices, namely the solution of the heat transfer problem as part of the coupled electrical-thermal analysis of an IC. We investigate some typical numerical problems which can be found during evaluating of the time dependent solution of the heat diffusion equation for a 3D finite domain with an uniform heat source. Considering a surface heat source, the solutions obtained by means of the Large Time Greens Function and Small Time Greens Function are studied. A simple method to improve the computational efficiency is proposed. A comparison of different approaches is given as well.

Simulation of Electrical and Optical Interconnections for Future VLSI ICs

At present, metallic interconnections become the “bottleneck” of the further progress in VLSI technology. The optical solution is considered as an alternative that could allow overcoming the limitations but its advantage should be confirmed at the level of modeling approach. The clock distribution network (CDN) that is the most representative component of the modern VLSI circuits has been used as the test circuit and its numerical models for H-tree architecture have been worked out and used. The model of the electrical CDN as well as some results of simulations presenting its expected features, also with the comparison to the results obtained for its optical counterpart are presented.

Simulations for thermal analysis of MOSFET IPM using IMS substrate

The project was focused on the thermal aspects of the new IPM module design. The investigations were aimed to estimate the influence of the particular design of the MOSFET transistor location versus the steady-state thermal feature of the considered IPM and to determinate its thermal impedance as well as to evaluate its equivalent RC network (ladder) model. It required working out the 3-D thermal model of the considered system that was used in numerical simulations and next, tested with commercial software, ANSYS 5.7 based on Finite Element Method (FEM).

Dynamic simulations for thermal analysis of MOSFET IPM on IMS substrate

The authors introduce some further research on the problem depicted in [1]. The transient model has been worked out to check how rapidly the temperature of the chip changes when the applied power changes abruptly This means searching for the answer: how the thermal resistance and the maximum temperature vary versus time. The simulations required using the 3-D thermal model of considered system that was used in numerical simulations and next, tested with commercial software, ANSYS 5.7 based on Finite Element Method (FEM) and additional calculations.