Comparative FEM thermo-mechanical simulations for built-in reliability: surface mounted technology versus embedded technology for silicon dies

International audienc

Investigating the effects of uniaxial pressure on the preparation of MgTiO3–CaTiO3 ceramic capacitors for MRI systems

Abstract Today's healthcare system relies on magnetic resonance imaging (MRI) for early diagnosis and treatment planning. For open MRI systems to achieve resolutions of about a hundred microns, a high voltage is required, as well as a specialized power supply. Negative–positive–zero (NP0) ceramic is selected for the fabrication of adjustable capacitors. Specifically, it stands for which is a classification based on the temperature coefficient of capacitance (TCC) of the ceramic material used in the capacitor. NP0 capacitors have a TCC of 0 ±30 ppm/°C, which means that their capacitance value does not change significantly with temperature and frequency. They are known for their stability and low losses, making them ideal for applications that require high accuracy and reliability, such as timing circuits for radio frequency (RF) applications. Here, MgTiO3–CaTiO3 ceramic is used to make an adjustable capacitor with desired properties for MRI systems. To enhance the dielectric properties of MgTiO3 ceramics, CaTiO3 was added in varying concentrations. After pressing and sintering, the resulting samples were tested using a vector network analyzer in the frequency range of 10–130 MHz. The adjustable capacitor fabricated using high co‐fired NP0 ceramic may have been used for MRI applications such as tuning circuits and matching networks, where precise capacitance values and low loss are critical. MRI systems with resonance frequencies of 128 MHz require trimmers with ceramic cores (VBreakdown = 3 kV @ 128 MHz, Cmin = 3 pF, CMax = 30 pF, and Cvariation step = 1.5 pF)

Methodology Based on Experiments and 3-D EM Simulations for Frequency Characterization of Buried Capacitors

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Predictive reliability using FEA simulations of power stacked ceramic capacitors for aeronautical applications

International audienceViscoplastic finite-element simulation was used to predict reliability of solder joints in a high temperature 4-chips stacked capacitor mounted on a PCB under temperature cycling (-55°C to +125°C, 45min ramps/60min dwells). A three-dimensional (3D) model was built considering the materials properties of a commercial component. Capacitor materials were determined by using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). Thermomechanical properties, Anand parameters and Darveaux constant of the materials were incorporated into the simulation procedure to evaluate the mechanical strains and the variations in the plastic energy density for the high temperature solder joints of the 4-chips stacked capacitor. The number of cycles before the crack initiation in the solder joint and the number of cycles to failure have been calculated using Darveaux methodology. The obtained results showed that the maximum mechanical strains were localized at the bottom chip. It has been found that the number of cycles to failure exceeded 50,000

Processing Functional Polymers for the Fabrication of Low-Cost Biomedical MEMS Sensors in an All-Organic Approach

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Fabrication of High Capacitance Density Capacitor Using Spray Coated Ba0.6Sr0.4TiO3 Thin Films

International audienc

Spray coating of Ba0.6Sr0.4TiO3 nanoparticles: a low-cost and scalable process for the deposition of dielectric thin films

International audienc

Ba0.6Sr0.4TiO3 nanocrystals self assembly into thin films for the development of high capacitance Metal-Insulator-Metal (MIM)

International audienc