On Finding an Equivalent Force to Mimic the Multilayer Ceramic Capacitor Vibration

The Multilayer Ceramic Capacitor (MLCC) Can Vibrate Due to the Piezoelectric Effect When There is AC Noise on the Power Rail. the Vibration of the Capacitor Will Generate a Force on the PCB and Thus Cause the PCB Vibration and Audible Problems May Occur. the Work in This Paper Finds an Equivalent Force with Similar Behavior to the MLCC-Generated Force. the Force is Controllable and Knowable and Thus Can Mimic the Capacitor Vibration on the PCB

Design and Implementation of an Automated Pick and Place System for Johanson Technology, Inc.

Johanson Technology, a capacitor and microelectronic part manufacturer, located in Camarillo, CA has forecasted a 50% increase in demand for single layer capacitors for the year 2011. Johanson chose to hire an intern to design and implement a robotic pick and place system to meet this demand. A complete automated system composed of a Stäubli RS20 robotic arm, CS8C-M Controller, and Electrosort Bowl Feeder needed to be integrated into an environment where no system currently existed. A bill of materials and parts list indicated that the entire system would be a fixed cost of $50,104. This proved to be the superior choice over the alternatives of hiring an outside consultant to design the system for$115,051 or hiring an additional employee to hand pick and place the parts for nearly $24,000 annually. Programs were written in VAL3, Stäubli’s own programming language, for the RS20 to pick and place parts in a grid formation onto Waffle, Gel, and Ring Packs. A custom tool composed of manufactured and purchased parts was made at Johanson Technology and held by the RS20 arm to handle the single layer capacitors. Performance of the system’s placement accuracy was analyzed by measuring correct placements on Waffle, Gel, and Ring Packs. Waffle Packs received a placement accuracy of 99.21%, missing around 10-20 parts out of 2,400. Gel Packs received 99.71% accuracy, and Ring Packs failed to place parts consistently within their 2-3⁰ rotation tolerance so their accuracy of placement could not be measured. The robotic pick and place system places single layer capacitors into Waffle, Gel, and Ring Packs at two to three times the speed of a human operator. At this rate, Johanson Technology will be able to meet their demand

Correlative Framework of Techniques for the Inspection, Evaluation, and Design of Micro-electronic Devices

Trillions of micro- and nano-electronic devices are manufactured every year. They service countless electronic systems across a diverse range of applications ranging from civilian, military, and medical sectors. Examples of these devices include: packaged and board-mounted semiconductor devices such as ceramic capacitors, CPUs, GPUs, DSPs, etc., biomedical implantable electrochemical devices such as pacemakers, defibrillators, and neural stimulators, electromechanical sensors such as MEMS/NEMS accelerometers and positioning systems and many others. Though a diverse collection of devices, they are unified by their length scale. Particularly, with respect to the ever-present objectives of device miniaturization and performance improvement. Pressures to meet these objectives have left significant room for the development of widely applicable inspection and evaluation techniques to accurately and reliably probe new and failed devices on an ever-shrinking length scale. Presented in this study is a framework of correlative, cross-modality microscopy workflows coupled with novel in-situ experimentation and testing, and computational reverse engineering and modeling methods, aimed at addressing the current and future challenges of evaluating micro- and nano-electronic devices. The current challenges are presented through a unique series of micro- and nano-electronic devices from a wide range of applications with ties to industrial relevance. Solutions were reached for the challenges and through the development of these workflows, they were successfully expanded to areas outside the immediate area of the original project. Limitations on techniques and capabilities were noted to contextualize the applicability of these workflows to other current and future challenges

MODELING THE PHYSICS OF FAILURE FOR ELECTRONIC PACKAGING COMPONENTS SUBJECTED TO THERMAL AND MECHANICAL LOADING

This dissertation presents three separate studies that examined electronic components using numerical modeling approaches. The use of modeling techniques provided a deeper understanding of the physical phenomena that contribute to the formation of cracks inside ceramic capacitors, damage inside plated through holes, and to dynamic fracture of MEMS structures. The modeling yielded numerical substantiations for previously proposed theoretical explanations. Multi-Layer Ceramic Capacitors (MLCCs) mounted with stiffer lead-free solder have shown greater tolerance than tin-lead solder for single cycle board bending loads with low strain rates. In contrast, flexible terminations have greater tolerance than stiffer standard terminations under the same conditions. It has been proposed that residual stresses in the capacitor account for this disparity. These stresses have been attributed to the higher solidification temperature of lead free solders coupled with the CTE mismatch between the board and the capacitor ceramic. This research indicated that the higher solidification temperatures affected the residual stresses. Inaccuracies in predicting barrel failures of plated through holes are suspected to arise from neglecting the effects of the reflow process on the copper material. This research used thermo mechanical analysis (TMA) results to model the damage in the copper above the glass transition temperature (Tg) during reflow. Damage estimates from the hysteresis plots were used to improve failure predictions. Modeling was performed to examine the theory that brittle fracture in MEMS structures is not affected by strain rates. Numerical modeling was conducted to predict the probability of dynamic failure caused by shock loads. The models used a quasi-static global gravitational load to predict the probability of brittle fracture. The research presented in this dissertation explored drivers for failure mechanisms in flex cracking of capacitors, barrel failures in plated through holes, and dynamic fracture of MEMS. The studies used numerical modeling to provide new insights into underlying physical phenomena. In each case, theoretical explanations were examined where difficult geometries and complex material properties made it difficult or impossible to obtain direct measurements

Microstructure evolution during sintering of multilayer ceramic capacitors: nanotomography and discrete simulations

Multi-Layer Ceramic Capacitors (MLCCs) are key passive components in modern electronics. MLCCs consist of alternating metal electrode and ceramic dielectrics layers. In ultrathin MLCC chips, the micrometric layers are composed of submicrometric metal and ceramic powders and nano sized ceramic additives (to retard the sintering of electrode and minimize the sintering mismatch). A number of defects such as cracks, delamination of layers and electrode discontinuity and homogeneity, may arise in the processing of these ultrathin MLCCs. The cracks and delamination result in product rejection. Electrode discontinuities (uncovered areas) and thickness homogeneity generate a number of problems including capacitance loss, electrical short, leakage current and decreased reliability. It is generally recognized that these defects are linked to the sintering kinetics mismatch between electrode and dielectric materials, during the co-firing (co-sintering) process of MLCCs. However, when it comes to the origin of these defects and to their evolution during the sintering process, little knowledge is available. Conventional post-sintering and 2-dimensional (2D) imaging methods suffer limitations. In this context, in-situ synchrotron X-ray imaging and Discrete Element Method (DEM) have been carried out to explore the origin and the evolution of defects during the co-sintering process. X-ray imaging including 2D radiography and 3-dimensional (3D) nano computed tomography (X-ray nCT) enable non-destructive in-situ observation of the microstructure change in 2D and 3D. In parallel, DEM can simulate the sintering of MLCCs by taking into account the powders’ particulate nature (particle size, packing, etc.) Synchrotron (Advanced Photon Source, Argonne National Laboratory, IL, USA) X-ray based Transmission X-ray Microscope (TXM) with spatial resolution of 30 nm was used to characterize a representative cylindrical volume of Ø 20 µm × 20 µm extracted from a 0603 (1.6 mm×0.8 mm) case size Nickel (Ni)-electrode Barium Titanate (BaTiO3, or BT)-based MLCC before and after sintering under 2H2%+Ar atmosphere. 3D tomographic microstructure imaging shows that the final electrode discontinuity is linked to the initial heterogeneity in the electrode layers. In situ X-ray radiography of sintering (heating ramp of 10 oC, holding at 1200 oC for 1 hour, cooling ramp -15 oC) of a Palladium (Pd) electrode BNT (Barium-neodymium-titanate) based MLCC representative volume was also carried out. It confirmed that discontinuities in the electrode originate from the initial heterogeneities, which are linked to the very particulate nature of the powder material. The discontinuity occurs at the early stage of the sintering cycle. At this stage, the electrode starts to sinter while the dielectric material may be considered as a constraining substrate. Correlative studies using Focused Ion Beam - Scanning Electron Microscope (FIB - SEM) tomography were conducted on green and sintered MLCC samples at high resolution (5 × 5 × 5 nm3). FIB images confirmed that the resolution of the X-ray nCT is sufficient to deal with these heterogeneity evolutions. Still, FIB tomography allows the X-ray nCT to be re-interpreted more accurately. Also, it provides detailed particulate parameters for the DEM simulations. The DEM was used to simulate the microstructure of a multilayer system during sintering. These simulations operate at the particle length scale and thus recognize the particulate nature of the multilayers at the early stage of sintering. First, the sintering of Ni matrix with BT inclusions was simulated using the dp3D codes (developed at SIMaP/GPM2, Université de Grenoble, France). The retarding effect of BT inclusions on the sintering of Nickel matrix was predicted by varying the size, the amount and the homogeneity of inclusions. It is found that the densification rate of the matrix decreases with increasing volume fraction of inclusions and with decreasing size of inclusions. For a given volume fraction and size of inclusions, a better dispersion of the inclusions results in a stronger retardation of the densification kinetics of the nickel matrix. Co-sintering of BT/Ni/BT multilayers was simulated with DEM by taking into account the particulate nature collected from the high resolution FIB nanotomography (FIB-nT) data, such as particle size, size distribution, heterogeneities, pores, and geometry. The temperature profile was also reproduced in these simulations. It is found that the electrode discontinuities originate from the initial heterogeneities in the green compact and form at the early stage of sintering under constraint, in good correspondence to the experimental observations. Parametric studies suggest that electrode discontinuities can be minimized by homogenizing the packing density and thickness of the electrodes and using a fast heating rate. Based on both experimental and DEM simulation results, a general conclusion is reached: the final discontinuity originates from the initial heterogeneity in the electrode layers and occurs at the early stage of sintering when the dielectric layers constrain the electrode layers. A defect evolution mechanism is proposed: after the lamination of BT sheets, there exist inevitably heterogeneous regions in the electrodes. Below 950-1000 oC, the nickel powder densifies except in heterogeneous zones for which desintering has been observed. At this stage, the Ni layers are under tensile stress. Tensile stresses in the thinner sections induce matter flow towards the thicker sections until the thinner sections are disrupted and discontinuities form. Once nickel is fully dense, electrodes are subjected to compressive stress at high temperature (1100 oC) due to BT densification. The compressive stress causes contraction of the viscous nickel, resulting in swelling of electrodes and hence a further increase in electrode discontinuity. Meanwhile, the nano-sized BT additives are expelled due to their unwettability with Ni at high temperature. The aggregated BT additives sinter, possibly forming percolation between two adjacent BT layers and enhancing the mechanical adhesion between Ni and BT layers in the MLCCs

Recent Advances in Perovskites: Processing and Properties

International audienceThe perovskite structure is one of the most wonderful to exist in nature. It obeys to a quite simple chemical formula, ABX3, in which A and B are metallic cations and X, an anion, usually oxygen. The anion packing is rather compact and leaves interstices for large A and small B cations. The A cation can be mono, di or trivalent, whereas B can be a di, tri, tetra, penta or hexavalent cation. This gives an extraordinary possibility of different combinations and partial or total substitutions, resulting in an incredible large number of compounds. Their physical and chemical properties strongly depend on the nature and oxidation states of cations, on the anionic and cationic stoichiometry, on the crystalline structure and elaboration techniques, etc. In this work, we review the different and most usual crystalline representations of perovskites, from high (cubic) to low (triclinic) symmetries, some well-known preparation methods, insisting for instance, in quite novel and original techniques such as the mechanosynthesis processing. Physical properties are reviewed, emphasizing the electrical (proton, ionic or mixed conductors) and catalytic properties of Mn- and Co-based perovskites; a thorough view on the ferroelectric properties is presented, including piezoelectricity, thermistors or pyroelectric characteristics, just to mention some of them; relaxors, microwave and optical features are also discussed, to end up with magnetism, superconductivity and multiferroïsme. Some materials discussed herein have already accomplished their way but others have promising horizons in both fundamental and applied research. To our knowledge, no much work exists to relate the crystalline nature of the different perovskite-type compounds with their properties and synthesis procedures, in particular with the most recent and newest processes such as the mechanosynthesis approach. Although this is not intended to be a full review of all existing perovskite materials, this report offers a good compilation of the main compounds, their structure and microstructure, processing and relationships between these feature

Designing Dielectric Materials through Complex Metal Oxides

This dissertation demonstrated that the electrical properties of complex oxide-based perovskite materials could be controlled through the careful modification of both material composition and structure. This was first shown through the modification of lead zirconate titanate (Pb(Zr0.52Ti0.48)O3, PZT) solid solutions with bismuth indate (BiInO3, BI) where the relative stability of the parent PZT phases, tetragonal (P4mm) and rhombohedral (R3m,) were shifted with increasing additions of BI. There were also observations of a correlated reduction in the Curie temperature with increasing additions of BI. Control over the electrical properties was also demonstrated through the modification of the Ba0.85Ca0.15(Zr0.10Ti0.90)O3 solid solution with Bi(Zn0.50Ti0.50)O3 through the disruption of long-range ferroelectric dipole order, resulting in a relaxor ferroelectric phase with a very high permittivity over a very large temperature range. Studies into BI modified PZT solid solutions showed the formation of stable solid solutions with the incorporation of BI at up to 10 mol% for PZT compositions with a Zr:Ti ratio of 50:50, and with up to 15 mol% BI with a Zr:Ti ratio of 52:48. Dielectric and ferroelectric studies were carried out on xBI – (1-x) PZT (52/48) samples for 0% ≤ x ≤ 10%. These studies showed a decrease to the Curie temperature from 390°C at 0% BI to 325°C at 10% BI, a transition in the room temperature ferroelectric phase from tetragonal at 0%, to mixed tetragonal and rhombohedral at 2.5%, to rhombohedral at 5% and above, and a variation to the high temperature phase transitions prior to the cubic paraelectric phase resulting in a rhombohedral to tetragonal phase transition in the 10% BI composition. Ferroelectric studies showed all samples to saturate at approximately 40 kV/cm upon which polarization loops of a normal ferroelectric were observed with coercive fields ranging from 10.8 kV/cm to 14.1 kV/cm, remanent polarizations ranging from 7.4 C/cm2 to 12.1 C/cm2, and maximum polarizations ranging from 18.4 C/cm2 to 24 C/cm2 (properties summarized from a maximum applied field of 50 kV/cm.) Piezoelectric studies were carried out on 2.5% BI – PZT (52/48) samples showing an average maximum strain of 0.2% correlating to an inverse piezoelectric coefficient (d33*) of 280 pC/N at 70 kV/cm. The modification of the ferroelectric Ba0.85Ca0.15(Zr0.10Ti0.90)O3 solid solutions with 1% Bi(Zn0.50Ti0.50)O3 resulted in a high permittivity relaxor ferroelectric phase. The induced relaxor phase was observed to be very sensitive to both processing effects and stoichiometry, with small modifications to processing parameters resulting in complex changes to the magnitude of the permittivity and the size distribution of PNRs, as evidenced by shifts in the observed Tmax. The desirable high permittivity relaxor phase was determined to be dependent on the existence of secondary phases, as single-phase samples were observed to maintain relaxor character in the dielectric properties while exhibiting relatively low permittivity. The existence of secondary phases was determined to be a function of cooling rate, with increased cooling rates showing lesser impurities, and bismuth oxide excess, as opposed to being determined by maximum sintering temperature. This material was found to be promising for multi-layer ceramic capacitor applications, though further research is needed into mitigating space charge contributions to the permittivity

High Efficiency and High Sensitivity Wireless Power Transfer and Wireless Power Harvesting Systems.

In this dissertation, several approaches to improve the efficiency and sensitivity of wireless power transfer and wireless power harvesting systems, and to enhance their performance in fluctuant and unpredictable circumstances are described. Firstly, a nonlinear resonance circuit described by second-order differential equation with cubic-order nonlinearities (the Duffing equation) is developed. The Duffing nonlinear resonance circuit has significantly wider bandwidth as compared to conventional linear resonators, while achieving a similar level of amplitude. The Duffing resonator is successfully applied to the design of WPT systems to improve their tolerance to coupling factor variations stemming from changes of transmission distance and alignment of coupled coils. Subsequently, a high sensitivity wireless power harvester which collects RF energy from AM broadcast stations for powering the wireless sensors in structural health monitoring systems is introduced. The harvester demonstrates the capability of providing net RF power within 6 miles away from a local 50 kW AM station. The aforementioned Duffing resonator is also used in the design of WPH systems to improve their tolerance to frequency misalignment resulting from component aging, coupling to surrounding objects or variations of environmental conditions (temperature, humidity, etc.). At last, a rectifier array circuit with an adaptive power distribution method for wide dynamic range operation is developed. Adaptive power distribution is achieved through impedance transformation of the rectifiers’ nonlinear impedance with a passive network. The rectifier array achieves high RF-to-DC efficiency within a wide range of input power levels, and is useful in both WPT and WPH applications where levels of the RF power collected by the receiver are subject to unpredictable fluctuations.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133338/1/tinyfish_1.pd

Fabrication of advanced ceramics and selective metallization of non-conductive substrates by inkjet printing

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 30/10/2002.Inkjet printing of ceramic components and gold conductive tracks was carried out in this study. A commercial inkjet printer, designed for printing one layer of 2D images on paper, was modified to give adequate resolution, to reverse the substrate for overprinting many layers and to accommodate the increase in thickness of 3D components during printing. Ceramic inks were prepared by wet ball milling and printed to form 3D structures. The powders used were alumina, zirconia, lead zirconate titanate (PZT) and barium titanate. The substrate used for printing the ceramic parts was an overhead transparency. Methods to stop or reduce ink flow were devised and used during printing of the ceramic parts. The alumina and zirconia powders were used for the fabrication of multi-layered laminates. The lead zirconate titanate was used to fabricate components with pillars, walls, vertical channels and x-y-z channel network. During printing of the x-y-z channel network, carbon was used as a support structure and then removed during firing. Barium titanate and carbon powders were used to form the first storey of a capacitor with a multi-storey car park structure. The printed parts were pyrolysed and fired in an oxidising environment and then characterised with scanning electron microscopy. The causes of micro structural defects found were discussed and prevention methods suggested. Organic gold powder was dissolved in methanol and then printed on three different substrates to form conductive gold tracks. The substrates used included alumina, glazed tile and microscope glass slides. The printed tracks were fired in air. The decomposition characteristics of the organic gold compound were studied with TGA and Differential Scanning Calorimetry (DSC). Scanning electron microscope was used to examine the fired gold film for defects and conductivity measurement of the tracks was carried out with a programmable multimeter