Ilja Belov

Recent progress in pulse reversal plating of copper for electronics applications

Abstract Based on demands for modern printed circuit board (pcb) manufacturing, the copper electroplating process is discussed. Electroplating from an additive free solution using low frequency pulse reversal plating with superimposed cathodic pulsation is suggested, which meets the demands for precise dimensions, high ductility and conductivity, low costs and environmental friendliness.

Experimental analysis and modelling of textile transmission line for wearable applications

Purpose – The paper seeks, by means of measurement and modelling, to evaluate frequency dependent per‐unit‐length parameters of conductive textile transmission line (CTTL) for wearable applications and to study deterioration of these parameters when CTTL is subjected to washing.Design/methodology/approach – The studied transmission line is made of Nickel/Copper (Ni/Cu) plated polyester ripstop fabric and is subjected to standard 60°C cycle in a commercial off‐the‐shelf washing machine. The per‐unit‐length parameters (resistance and inductance) and characteristic impedance of the line are extracted from measurements before and after washing. Using the measurement data an equivalent circuit is created to model the degradation of the line. The circuit is then integrated in a three‐dimensional transmission line matrix (TLM) model of the transmission line.Findings – Both an electrical equivalent circuit and a TLM model are developed describing the degradation of the conductive textile when washed. A severe det...

CFD Aided Reflow Oven Profiling for PCB Preheating in a Soldering Process

A CFD-aided reflow oven profile prediction algorithm has been developed and applied to modelling of preheating of a PCB with non-uniform distribution of component thermal mass in a forced air convection solder reflow oven. The iterative algorithm combines an analytic approach with CFD modelling. It requires an experimentally validated CFD model of the solder reflow oven and a CFD model of the PCB as main inputs. Results of computational experiments have been presented to reveal good agreement between predicted PCB profiles and corresponding CFD calculations. Application guidelines contained in the description of the algorithm will assist potential users both during the virtual prototyping phase of a PCB including designing for assembly and in the phase of reflow oven profiling.

Influence of process parameters on crack formation in direct current and pulse reversal plated hard chromium

Abstract It has for a long time been known that crack free chromium coatings can be obtained by pulse reversal plating, but it has only much later been understood that reoxidation of hydrogen from the surface during the anodic periods is essential for obtaining crack free deposits. In this paper, it is shown that a specific anodic charge depending on the charge of the previous cathodic pulse is needed to obtain a crack free coating and that residual stress in the coating will be less at more frequent current reversals. Furthermore, too large an anodic charge will result in redissolution of chromium and thereby decrease the current efficiency.

Application of CFD modelling for energy efficient humidity management of an electronics enclosure in storage under severe climatic conditions

A CFD modelling methodology including experimental validation has been developed and applied for investigation of anti-moisture measures in a non- hermetic electronics enclosure containing a number of printed circuit boards, and placed in a severe storage environment. In the climatic test the temperature and the relative humidity have been varried from +33degC to +71degC and from 14% to 80%, respectively. Enclosure heater solutions have been parametrically studied by simulation. A heating strategy involving various power levels has been determined, which is just sufficient to maintain the internal relative humidity below 60%, thereby reducing the risk for dew formation on the electronics assembly.

Influence of anodic pulses and periodic current reversion on electrodeposits

Abstract This paper discusses how anodic pulses and periodic current reversion influence electrodeposition. Depending on the involved metal and electrolyte, very different effects can be observed and taken advantage of. The Wagner number, Wa, describing the current distribution is shown to be useful for predicting the throwing power at low frequencies of current reversion, even in complex electrochemical systems, but is less useful at higher frequencies. Passivation can occur due to oxide formation, super-saturation of metal salts or depletion of complexing agents at the electrode surface. Furthermore, dissolution and desorption processes in the anodic period can have strong influence on the succeeding cathodic electrocrystallisation affecting preferred crystal orientation, intrinsic stress and current efficiency. A literature survey is combined with experiments from silver plating from a cyanide bath.

A computational method for evaluating the damage in a solder joint of an electronic package subjected to thermal loads

Purpose – The purpose of this paper is to introduce a novel computational method to evaluate damage accumulation in a solder joint of an electronic package, when exposed to operating temperature en ...

Pulse and pulse reverse plating of copper from acid sulphate solutions

Abstract This paper describes how copper plating is influenced by modulated current. By unipolar pulse plating smooth, compact and fine grained structures can be obtained, but the macro throwing power is worse than by direct current plating. The best throwing power is obtained by pulse reverse plating. In additive containing solutions, excellent throwing power has been obtained at the following parameters: T c/T a=20, i a/i c=1–3·5 and Q a/Q c<0·2. Without additives the surface becomes less smooth. Finally, superimposed pulse reverse plating has the possibility to combine the advantages of uni- and bipolar pulse plating in an additive free process.

A Simulation-based Spectral Technique for Power Quality and EMC Design of an Independent Power System

A novel simulation-based spectral technique for power quality and electromagnetic compatibility (EMC) design of an independent electrical power system (EPS) has been proposed. Power filter optimization problem has been formulated to provide full solution of the electric power quality and conducted EMI problems in the EPS. The spectral technique has been implemented within a CAD tool. An example of power quality and EMC design has been provided for an independent EPS where an AC power source generates a power, which is comparable to the consumed power, and an additional power filter is calculated for an electronic product including a switch-mode power supply. Current and voltage spectra calculations have been verified with a block-oriented simulation program Simulink. Numerical experiments revealed a number of important features of the proposed spectral technique.

Thermal and flow analysis of SiC-based gas sensors for automotive applications

Different block and tube mounting alternatives for SiC-based gas sensors were studied by means of temperature measurements and simulation of heat transfer and gas flow for steady state conditions. The most preferable tube mounting design was determined. Simulation-based guidelines were developed for designing tube-mounted gas sensors in the exhaust pipes of diesel and petrol engines, taking into account thermal constraints and flow conditions.