Ciprian Ionescu

Accurate 3D modelling and simulation of advanced packages and vertical stacked dice

In previous papers, the authors have investigated planar configurations existing in high-density interconnection (HDI) structures from the electromagnetic and signal integrity viewpoints (using 2.5D field solvers), offering solutions to signal integrity (SI) and electromagnetic compatibility (EMC) concerns . This paper presents new investigations and results focused on 3D modelling and simulation of advanced packages (SIP- system in package, SOP - system on package) and vertical stacked dice. A system-in-a-package or system in package, also known as a chip stack MCM, has a number of integrated circuits enclosed in a single package or module. The SIP performs all or most of the functions of an electronic system. System-on-package (SOP) is the new emerging system technology that goes beyond system-on-chip (SOC) and system-in-package (SIP) and forms the basis of all emerging digital convergent electronic and bio-electronic systems.

Pulsed behavior of polymer protection devices

Polymer protection devices are placed on circuit boards as chip devices to protect existing electronic devices from electrostatic discharge events (ESD). As there are no generally accepted standards for characterization of such devices, we used Transmission Line Pulsing (TLP) to determine trigger- and clamping- voltages as well as leakage currents. Using short duration pulses (less than 10 ns) from a Very-Fast Transmission Line Pulser (VF-TLP) gives information of the transient behavior during pulsing. The influence of the pulse width and amplitude on the current-voltage behavior was investigated on chip size polymer voltage suppressors.

Electrical stress on film resistive structures on flexible substrates

There is a necessity to include sensors, e.g. on the basis of resistors, in the design of organic electronic devices in order to extend the range of possible applications, mentioned in the last iNEMI roadmap (2009). It is essential to identify potential organic resistive materials, the processes and methods to structure them and to characterize their resistive properties on flexible substrates including their reliability. In this paper we focus on the resistive properties of conductive polymer screen printed in a roll-to-roll process on foil.

Thermal simulation of a high power loudspeaker

Simulation of electromechanical systems is nowadays subject of very intensive investigation, mainly due to newly developed MEMS devices. There are numerous papers in relation to piezoelectric transformers and other piezoelectric transducers. Although not a MEMS, a loudspeaker is an electromechanical device, which study could offer interesting results and the approach can be transposed to other similar devices. For this paper which is a first approach on the subject, we have the intention to realize a thermal analysis, having as source the electrical power applied to the device. This analysis is done in order to establish a power level limit of a prototype loudspeaker. The finite element model will serve also as a basis for a further optimization and an acoustic analysis.

Analysis of reflections for different electronic modules

In the paper we analyzed the reflections for different electronic modules, and for this we computed, simulated and measured the voltage of reflection for different situations. For a complex evaluation of reflection, different experimental electronic modules are realized: double PCB realized in classical technology (with FR4 substrate) and FELA (special laminates and structures having various types of glass as base and dielectric substrate, or even a conductive substrate such as solid aluminum and the dielectric as a thin sheet between the base metal and the layer containing traces); and the technological type of digital circuit. The measured results are compared with computed and simulated results. An interesting comparison is realized between the FR4 and FELA technology.

Optimal microheater Patterns with PEDOT:PSS conductors for flexible sensor applications

This paper continues the study in the field of microheaters on flexible substrates. The idea of using flexible substrates comes together with the need for low manufacturing costs, having in mind the applications of sensors for home usage and other possible applications as monitors for buildings or basements where possible toxic gases can be accumulated, for instance mathane, carbon monoxide or carbon dioxide. In the current paper we propose the use of poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid (PEDOT:PSS) as active heating element. The data from literature and our previous experiments have proven that this material can be used as resistive material having the possibility to operate within the desired range of temperatures for sensor applications, between 80 and 100 °C. The test samples with different patterns will be prepared by ink-jetting, with silver ink used as terminations.

Sensing properties of carbon nanotube based thick film layers on foils

Carbon nanotubes (CNT) have remarkable electrical, mechanical, thermal and optical properties. CNT-polymer composites are therefore alternative materials for applications, like flexible electrodes in displays, electronic paper, antistatic coatings. But these materials can also be used as sensors, due to their special properties. The paper describes the behavior of CNT-based thick film layers on foils due to electrical, thermal, optical, and mechanical stimuli. Possible applications as sensor materials are further described.

Electrical stress on transparent conductive oxide layer

Transparent conductive oxides (TCO) are a class of materials with good electrical conductivity and low visible light absorption. Their properties can be tuned by additional doping and by deposition techniques. In this way their applications are as active and passive electronic and opto-electronic devices. In this paper we present the electrical properties of an antimony doped tin oxide (ATO) layer deposited by screen printing techniques in a roll-to-roll process. We focus on the DC-and pulsed behavior of this conductive layer on flexible substrates and the resulting changes of his resistive properties under normal and stressed conditions.

Pulsed stress behavior of flexible thick film resistors

In order to investigate the behavior for very high current densities on polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of transmission line pulsing (TLP) allows, on the basis of square pulses, the in-situ monitoring of the voltages and currents at the device under test (DUT) during pulsing and helps to gain fundamental insights into the electrical behavior at higher current densities. The influence of the pulse amplitude on the current-voltage behavior was investigated on thick film carbon-based polymer resistors on flexible foil, like polyimide (Kapton). The resistance change due to an applied high voltage pulse stress is a measure of the ESD susceptibility of the thick film polymer resistors. The measurements show that the thick film flexible, carbon based resistors on Kapton foil are susceptible to high energy pulses. Parametric failure or catastrophic damage can occur.

Chemo-optical sensor for toxic gases detection

Many applications in the field of toxicology and laboratory medicine as well as some air pollution applications require low concentrations levels for toxic gas detection and its real-time monitoring. The authors have designed and manufactured an experimental integrated chemo-optical sensor on silicon containing a sol-gel layer, a silicon nitride waveguide and a silicon photodiode. The first measurements realized on an experimental structure show a good correlation with the requirements of the Romanian standards in the fields as well as EPA standards