Bartosz Platek

Molecular dynamics study of the chiral vector influence on thermal conductivity of carbon nanotubes

Current paper focuses on the influence of chiral vector on thermal conductivity of carbon nanotubes. The non-equilibrium molecular dynamic technique was implemented in commercially available software. The eleven single-walled CNTs of various chirality (from zigzag to armchair) was investigated. Moreover, the influence of length on CNTs thermal conductivity was examined.

An accurate method for thermal conductivity measurement of thermally conductive adhesives

In the following paper the measurement method of thermal conductivity is described. These method was especially designed for measuring the thermal conductivity of the thermally conductive adhesives. The principal information about the experimental setup, mathematical model of experiment and the change of its uncertainty (calculated using type B method presented in ISO Guide for measurements) depended on measurement parameters are described. The obtained uncertainty from the model was compared with the real measurements of polymer composites filled with silver microflakes.

The study of carbon nanotube's length in reference to its thermal conductivity by molecular dynamics approach

Current paper focuses on the influence of carbon nanotube (CNT) length on its thermal conductivity. The powerful technique which is molecular modeling was used. The non-equilibrium molecular dynamics was implemented in commercially available software. The eight single-walled carbon nanotubes from 50 nm to 400 nm was investigated. The obtained results show the trend of increasing thermal conductivity for longer nanotubes.

An approach to measurement and evaluation of the thermal conductivity of the thermal adhesives in electronic packaging

In the following paper the measurement method of thermal conductivity is described. This method was especially designed for measuring the thermal conductivity of the thermal adhesives. The principal informations about heat transfer are given, and the experimental setup, mathematical model of experiment and its uncertainty with 95% of probability are shown. The thermal conductivity of polymer based material filled in 0.5% with carbon nanotubes is measured.

Non-equilibrium molecular dynamics simulation of heat transfer in carbon nanotubes - verification and model validation

Currently there is a lot of ongoing research towards estimation the thermal conductivity of carbon nanotubes (CNT). In the current paper thermal conductivity of SWNT were studied by using non-equilibrium molecular dynamics (NEMD) simulations (implemented in Materials Studio software, Accelerys Inc.). The NEMD technique is a direct approach which includes the computation of heat transport coefficients from flux-force relations, analogous to the macroscopic definition in irreversible thermodynamics. Simulations in nano- and atomic-scale can cause problems with model validation and with algorithm verification. The novel approach based on simulation of known material such as silicon were applied. The current paper focuses on the obtained results of model validation and verification of simulation algorithm.

Influence of meso–scale analysis parameters of cross–linked polymers on final simulation results

Molecular modeling is one of the fastest developing branch of material science. There are a couple of reasons of such a state: on one hand molecular modeling tools are nowadays quite easy to implement to selected problems and on the other hand experimental research and analysis might be impossible to made or too expensive in comparison to numerical modeling as an alternative. Anyway there is a question of accuracy but in some cases we are not so much interested in precise numbers but an estimation of a proper trend would be sufficient. Literature study shows that results achieved by application of advanced numerical modeling tools fulfills convergence criteria and fits quite well to experimental data. Recently some researchers concentrate on molecular mesoscale modeling of crosslink polymers. Preliminary study shows need for an investigation of dependency of simulation parameters (time length, time step, force field type, size of a bead ect.) for final results. It is a key for good estimation of Tg and CTE of polymers. Results of simulation help to optimize the performance of polymers materials in electronics technology Mesoscale results were compared with molecular modeling simulations. The results are promising.

Electrical, thermal and mechanical properties of epoxy composites with hybrid micro- and nano-sized fillers for electronic packaging

Combining conductive micro and nanofillers is a new way to improve electrical, thermal and mechanical properties of polymer composites for electronic packaging. Micrometric silver flakes and nanometric carbon nanotubes (CNT) exhibit high electrical and thermal conductivity. Moreover CNT improve strength, stiffness and fracture toughness of the polymer matrix. A new type of hybrid conductive adhesive filled with silver flakes and carbon nanotubes were investigated. Thermal and electrical conductivities were measured as well as improved mechanical properties were evaluated based on the reliability tests of joints made of tested material. The electrical, thermal and mechanical properties were consistent with the morphologies of the hybrid composites characterized by SEM.

Photonic sintering process of ink-jet printed conductive microstructures

In this paper the influence of photonic sintering process parameters on the resistance of ink-jet printed structures were examined. The sintering process was performed by delivering to samples an energy in the form of light pulses (1200 J per pulse). There was specified the factors which would have the most significant influence on the results (resistance of sintered structure) such as: distance between lamp and sample, number of pulses, temperature of substrate and substrate material. To evaluate the influence of this factors the design of the experiment technique (DoE) and Analysis of Variance for the results (ANOVA) were used.

The impact of carbon nanotubes diameter on their thermal conductivity - Non-equilibrium molecular dynamics approach

In the current paper the influence of diameter of finite-length zig-zag single-walled carbon nanotube (SWNT) on its thermal conductivity at room temperature in ballistic regime was described. The fourteen types of SWNT with various chrality from (7,0) to (20,0) and with constant length (213 nm) were investigated. To calculate the thermal conductivity the non-equilibrium molecular dynamics technique was implemented in commercially available software for molecular modelling.

The method of measuring the efficiency of heat transfer through thermal interface materials in microelectronics packaging

The miniaturization trend of electronic devices and simultaneous increase of packaging density and clock frequency can generate the large amount of heat that appears during operation of such devices. The thermal interface materials (TIMs) are currently one of the most important materials used in electronic packaging, because their role is to reduce the thermal contact resistance between the heat source (i.e. silicon chip) and heat sink (i.e. substrate or package of integrated circuit). Such materials based on nano- and micro-sized additives can improve the efficiency of heat dissipation. Within the paper the method of measuring of the efficiency of heat transfer through structures with thermal interface materials which was based on measurement of temperature using thermographic IR camera was presented.