Vibration Reduction of MLCCS Using Vibration-Canceling Effects of Poling Process

2016 ◽  
Author(s):  
Dongjoon Kim ◽  
Byung-Han Ko ◽  
No-cheol Park ◽  
Young-Pil Park
Keyword(s):  
Fundamental Frequency ◽  
Opposite Direction ◽  
Piezoelectric Coefficient ◽  
Acoustic Noise ◽  
Vibration Reduction ◽  
Circuit Board ◽  
Poling Process ◽  
Dc Bias ◽  
Poling Voltage ◽  
Piezoelectric Characteristics

MLCC vibrates due to its piezoelectric characteristics and it makes circuit board vibrate and lead to acoustic noise. In order to reduce vibration, piezoelectric coefficient should be reduced. In this study, poling process was used to decrease piezoelectric coefficient. Due to the electrostriction coefficient, response at fundamental frequency can be cancelled by applying voltage to opposite direction. Through the experiment, vibration-cancelling voltage increases as the poling voltage increases. Also, vibration-cancelling voltage increase inversely proportion to MLCC’s capacitance. By applying proper DC bias after poling process, vibration can be reduced.

Implementation of tunable resonators in planar groove gap waveguide technology

2021 ◽  
pp. 1-7
Author(s):  
Titus Oyedokun ◽  
Riana H. Geschke ◽  
Tinus Stander
Keyword(s):  
Printed Circuit Board ◽  
Tuning Range ◽  
Frequency Tuning ◽  
Resonant Cavity ◽  
Circuit Board ◽  
Resonant Cavities ◽  
Tunable Resonators ◽  
Simulation Strategy ◽  
Dc Bias ◽  
Continuous Frequency

Abstract We present a tunable planar groove gap waveguide (PGGWG) resonant cavity at Ka-band. The cavity demonstrates varactor loading and biasing without bridging wires or annular rings, as commonly is required in conventional substrate-integrated waveguide (SIW) resonant cavities. A detailed co-simulation strategy is also presented, with indicative parametric tuning data. Measured results indicate a 4.48% continuous frequency tuning range of 32.52–33.98 GHz and a Qu tuning range of 63–85, corresponding to the DC bias voltages of 0–16 V. Discrepancies between simulated and measured results are analyzed, and traced to process variation in the multi-layer printed circuit board stack, as well as unaccounted varactor parasitics and surface roughness.

Experimental Investigation by Speckle Interferometry of Solder Joint Failure Under Thermomechanical Load Aggravated by Boundary Conditions at Board Level

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
D. N. Borza ◽  
I. T. Nistea
Keyword(s):  
Solder Joint ◽  
Fundamental Frequency ◽  
Printed Circuit Board ◽  
Speckle Interferometry ◽  
Circuit Board ◽  
Joint Failure ◽  
Printed Circuit ◽  
Out Of Plane ◽  
Fringe Patterns ◽  
Board Level

Reliability of electronic assemblies at board level and solder joint integrity depend upon the stress applied to the assembly. The stress is often of thermomechanical or of vibrational nature. In both cases, the behavior of the assembly is strongly influenced by the mechanical boundary conditions created by the printed circuit board (PCB) to casing fasteners. In many previously published papers, the conditions imposed to the fasteners are mostly aiming at an increase of the fundamental frequency and a decrease of static or dynamic displacement values characterizing the deformation. These conditions aim at reducing the fatigue in different parts of these assemblies. In the photomechanics laboratory of INSA Rouen, the origins of solder joint failure have been investigated by means of full-field measurements of the flexure deformation induced by vibrations or by forced thermal convection. The measurements were done both at a global level for the whole printed circuit board assembly (PCBA) and at a local level at the solder joints where failure was reported. The experimental technique used was phase-stepped laser speckle interferometry. This technique has a submicrometer sensitivity with respect to out-of-plane deformations induced by bending and its use is completely nonintrusive. Some of the results were comforted by comparison with a numerical finite elements model. The experimental results are presented either as time-average holographic fringe patterns, as in the case of vibrations, or as wrapped phase patterns, as in the case of deformation under thermomechanical stress. Both types of fringe patterns may be processed so as to obtain the explicit out-of-plane static deformation (or vibration amplitude) maps. Experimental results show that the direct cause of solder joint failure may be a high local PCB curvature produced by a supplementary fastening screw intended to reduce displacements and increase fundamental frequency. The curvature is directly responsible for tensile stress appearing in the leads of a large quad flat pack (QFP) component and for shear in the corresponding solder joints. The general principle of increasing the fundamental frequency and decreasing the static or dynamic displacement values has to be checked against the consequences on the PCB curvature near large electronic devices having high stiffness.

Acoustic Noise/Vibration Reduction of a Single-Phase SRM Using Skewed Stator and Rotor

2013 ◽  
Vol 60 (10) ◽  
pp. 4292-4300 ◽  
Author(s):  
Hyong-Yeol Yang ◽  
Young-Cheol Lim ◽  
Hyun-Chul Kim
Keyword(s):  
Single Phase ◽  
Acoustic Noise ◽  
Vibration Reduction ◽  
Noise Vibration

Studies on the Dynamic Behavior of a Printed Circuit Board

1999 ◽  
Author(s):  
Hongfang Wang ◽  
Mei Zhao
Keyword(s):  
Natural Frequency ◽  
Dynamic Behavior ◽  
Fundamental Frequency ◽  
Strong Influence ◽  
Printed Circuit Board ◽  
External Environment ◽  
Circuit Board ◽  
Fe Modeling ◽  
Printed Circuit ◽  
Modeling Strategy

Abstract The dynamic behavior of printed circuit (PC) boards exercises strong influence on the reliability of electronic equipment. In this paper, the dynamic behavior of a PC board is studied by means of computation and verified by experiment with results compared favorably. This shows that FE modeling strategy used is sound. In general, excitement frequencies induced by external environment are in the range from several Hz to several hundred Hz. In order to avoid product failures due to resonance, it is desirable to make the fundamental natural frequency of PC boards as high as possible. Two structural modified design methods to raise the fundamental frequency are given with a numerical example.

scholarly journals Piezo-electrets from polypropylene composites doped with mineral fillers

2019 ◽  
Vol 91 (6) ◽  
pp. 967-982 ◽  
Author(s):  
Halina Kaczmarek ◽  
Marta Chylińska ◽  
Ewa Klimiec ◽  
Bogusław Królikowski ◽  
Grzegorz Sionkowski ◽  
...  
Keyword(s):  
Piezoelectric Coefficient ◽  
Constant Electric Field ◽  
Tensile Tests ◽  
Glass Beads ◽  
Field Sample ◽  
Polypropylene Composites ◽  
Current Voltage ◽  
Mineral Fillers ◽  
Thermal Stability Of ◽  
Piezoelectric Characteristics

Abstract PP-based composites with two mineral fillers (perlite or glass beads) were manufactured by extrusion, and then subjected to orientation in a ratio of 3:1. Electrets were obtained in the polarization process under the influence of a constant electric field. Sample morphology was tested by SEM whereas the crystallinity was determined by XRD. Mechanical strength and thermal stability of composites was studied by tensile tests and thermogravimetric analysis, respectively. The piezoelectric characteristics were appointed by measurement of the electrical charge and current voltage in the polarized samples. The dependence of thermally stimulated depolarized current (TSDC) on temperature was also investigated. The piezoelectric coefficient (d33), the electret stability over time as well as activation energy of depolarization process have been determined. It was found that low filler content (i.e. 2.5 and 5 wt.% of glass beads and perlite, respectively) significantly improve piezoelectric properties of isotactic polypropylene (i-PP).

scholarly journals An Integrated Front-end Circuit Board for Air-Coupled CMUT Burst-Echo Imaging

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6128
Author(s):  
Lei Ye ◽  
Jian Li ◽  
Hui Zhang ◽  
Dongmei Liang ◽  
Zhuochen Wang
Keyword(s):  
Imaging System ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Ultrasonic Transducers ◽  
Circuit Board ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Front End ◽  
Field Programmable ◽  
Good Potential ◽  
Dc Bias

To conduct burst-echo imaging with air-coupled capacitive micromachined ultrasonic transducers (CMUTs) using the same elements in transmission and reception, this work proposes a dedicated and integrated front-end circuit board design to build an imaging system. To the best of the authors’ knowledge, this is the first air-coupled CMUT burst-echo imaging using the same elements in transmission and reception. The reported front-end circuit board, controlled by field programmable gate array (FPGA), consisted of four parts: an on-board pulser, a bias-tee, a T/R switch and an amplifier. Working with our 217 kHz 16-element air-coupled CMUT array under 100 V DC bias, the front-end circuit board and imaging system could achieve 22.94 dB signal-to-noise ratio (SNR) in burst-echo imaging in air, which could represent the surface morphology and the three-dimensional form factor of the target. In addition, the burst-echo imaging range of our air-coupled CMUT imaging system, which could work between 52 and 273 mm, was discussed. This work suggests good potential for ultrasound imaging and gesture recognition applications.

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