scholarly journals Design, Simulation, Fabrication, and Characterization of an Electrothermal Tip-Tilt-Piston Large Angle Micromirror for High Fill Factor Segmented Optical Arrays

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 419
Author(s):  
David Torres ◽  
LaVern Starman ◽  
Harris Hall ◽  
Juan Pastrana ◽  
Sarah Dooley
Keyword(s):  
Fill Factor ◽  
Performance Metrics ◽  
Coefficient Of Thermal Expansion ◽  
Large Angle ◽  
Single Element ◽  
Piston Motion ◽  
Electrothermal Actuation ◽  
Out Of Plane ◽  
Optical Phased Array ◽  
Micro Electromechanical System

Micro-electromechanical system (MEMS) micromirrors have been in development for many years, but the ability to steer beams to angles larger than 20° remains a challenging endeavor. This paper details a MEMS micromirror device capable of achieving large motion for both tip/tilt angles and piston motion. The device consists of an electrothermal actuation assembly fabricated from a carefully patterned multilayer thin-film stack (SiO2/Al/SiO2) that is epoxy bonded to a 1 mm2 Au coated micromirror fabricated from an SOI wafer. The actuation assembly consists of four identical actuators, each comprised of a series of beams that use the inherent residual stresses and coefficient of thermal expansion (CTE) mismatches of the selected thin films to enable the large, upward, out-of-plane deflections necessary for large-angle beamsteering. Finite element simulations were performed (COMSOL v5.5) to capture initial elevations and tip/tilt motion displacements and achieved <10% variance in comparison to the experiment. The measured performance metrics of the micromirror include tip/tilt angles of ±23°, piston motion of 127 µm at sub-resonance, and dynamics characterization with observed resonant frequencies at ~145 Hz and ~226 Hz, for tip/tilt and piston motion, respectively. This unique single element design can readily be scaled into a full segmented micromirror array exhibiting an optical fill-factor >85%, making it suitable for optical phased array beam control applications.

scholarly journals Dual Feed, Single Element Antenna for WiMAX MIMO Application

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Frank M. Caimi ◽  
Mark Mongomery
Keyword(s):  
Correlation Coefficient ◽  
Performance Metrics ◽  
Measured Data ◽  
Antenna Pattern ◽  
Relative Performance ◽  
Equal Length ◽  
Impedance Match ◽  
Single Element ◽  
Pattern Correlation ◽  
Operating Bandwidth

A novel u-shaped single element antenna having two feed ports is compared with two equal length monopoles separated by a distance equivalent to the width. A discussion of relative performance metrics is provided for MIMO applications, and measured data is given for comparison. Good impedance match and isolation of greater than  dB are observed over the operating bandwidth from 2.3 to 2.39 GHz. The antenna patterns are highly uncorrelated, as illustrated by computation of the antenna pattern correlation coefficient for the two comparison monopoles.

Silicon-integrated photonic circuit for a single-stage large-angle beam steering optical phased array

2010 ◽  
Author(s):  
David Kwong ◽  
YaZhao Liu ◽  
Amir Hosseini ◽  
Yang Zhang ◽  
Beomsuk Lee ◽  
...  
Keyword(s):  
Phased Array ◽  
Beam Steering ◽  
Large Angle ◽  
Single Stage ◽  
Optical Phased Array ◽  
Photonic Circuit

Robust Design of a Micro-Electromechanical System in the Presence of Assembly Uncertainty

2010 ◽  
Author(s):  
Choong-Ho Rhee ◽  
Kenn Oldham
Keyword(s):  
Damping Ratio ◽  
Weight Bearing ◽  
Open Loop ◽  
Alignment Error ◽  
Wide Range ◽  
Loop Dynamics ◽  
Out Of Plane ◽  
Micro Electromechanical System ◽  
Stiffness And Damping ◽  
Function Models

Three methods of minimizing error between the transient response of a dynamic system with parameter variation and its nominal open-loop dynamics are tested on a second-order example system of a piezoelectric microactuator. The example system is a piezoelectrically actuated silicon flexure intended for use in micro-robotic systems. Polymer and silicon layers are to be stacked on top of the original flexure to increase out-of-plane weight-bearing capacity, but this process is subject to substantial alignment error. The procedures evaluated in this paper seek target stiffness and damping coefficients that minimize error in open-loop actuator motion. The first method is based on simple damping ratio and natural frequency calculations, while the second and third methods are based on state-space and transfer function models, respectively. All three approaches reduce error in transient dynamics compared to nominal designs based solely on static weight-bearing or fabrication considerations, with the state-based being identified as usable to a wide range of systems, although the ability to reduce sensitivity to model variation in purely open-loop operation is limited.

Interactions Between Flip Chip Underfill and Solder Alloy

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
D. Blass ◽  
P. Borgesen
Keyword(s):  
Solder Alloy ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Moisture Sensitivity ◽  
Complex Issue ◽  
Shock Testing ◽  
Out Of Plane ◽  
Level 3 ◽  
Mechanical Optimization

The effects of underfill selection on flip chip reliability were always a complex issue. Mechanical optimization of the underfill performance, achieved by the addition of appropriate fillers, is invariably a tradeoff between the adhesion and the coefficient of thermal expansion (CTE) and, thus, also between in-plane and out-of-plane stresses. Another critical concern is the degradation of the underfill in processing and/or long term exposure to operating temperatures and ambient humidity. This is strongly affected by the chemical compatibility with combinations of solder mask, chip passivation, and flux residues. The latter is believed to be responsible for our observation of interactions with the solder alloy, too. As for the effects of glass transition temperatures and CTE, we find materials that were close to optimum for eutectic SnPb to be very far from the best options for lead free joints. We report on two sets of systematic experiments. The first addressed the performance of combinations of underfills, no-clean fluxes, and solder alloys in a JEDEC level 3 moisture sensitivity test. The second one involved thermal shock testing of flip chip assemblies underfilled with one of five different materials after soldering with SnCu, SAC305, and SnPb.

Constructive approach to reduce the influence of temperature on spring suspension eigenfrequencies

Sensor Review ◽  
2020 ◽  
Vol 40 (3) ◽  
pp. 297-309
Author(s):  
Pavel Baranov ◽  
Tamara Nesterenko ◽  
Evgenii Barbin ◽  
Aleksei Koleda
Keyword(s):  
Finite Element ◽  
Microelectromechanical Systems ◽  
Coefficient Of Thermal Expansion ◽  
Poisson Ratio ◽  
Dielectric Materials ◽  
Experimental Results ◽  
Internal Stresses ◽  
Elastic Suspension ◽  
Content Type ◽  
Out Of Plane

Purpose One of the problems encountered by developers of inertial systems, such as gyroscopes and accelerometers, is the critical dependence of the eigenfrequencies of elastic suspensions (ES) on temperature when using substrates for sensors made of dielectric materials, such as borosilicate glass. The internal stresses arising in the ES caused by the difference in the temperature coefficients of linear expansion (TCLE) lead to deformation of the sensor and complication of the electronic part of the sensor. The purpose of this paper is to approach for in-plane and out-of-plane ES are considered that allow for minimization of the influence of internal stresses on eigenfrequencies. Design/methodology/approach Analytical, finite element and experimental results are considered. The temperature coefficient of thermal expansion, the Young’s modulus and the Poisson ratio are given as a function of temperature. The shape of the spring elements (SEs) and the construction of the elastic suspension are the main topics of focus in this study. The authors’ out-of-plane ES based on a meander-like spring element implemented via finite element modeling show good agreement with the experimental results. Findings Meander-like SEs have been developed that have lower temperature errors in comparison with traditional types of SEs. The main contribution to the change in the eigenfrequency from temperature is made by internal stresses that arose from the deformation of the bonded materials with different TCLE. The change of eigenfrequency from the temperatures that were calculated by finite element method did not exceed 0.15%, however, in practice, the scatter of the obtained characteristics for different samples showed a change of up to 0.3%. Originality/value This study shows a way to design and optimize the structure and theoretical background for the development of the microelectromechanical systems (MEMS) inertial module combining the functions of gyroscope and accelerometer. The obtained results will improve and expand the manufacturing technology of MEMS gyroscopes and accelerometers.

scholarly journals A Holistic Study on the Effect of Annealing Temperature and Time on CH3NH3PbI3-Based Perovskite Solar Cell Characteristics

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohammad Ali Akhavan Kazemi ◽  
Arash Jamali ◽  
Frédéric Sauvage
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Figure Of Merit ◽  
Fill Factor ◽  
Crystallization Process ◽  
Annealing Temperature ◽  
Power Conversion ◽  
Perovskite Solar Cells ◽  
Out Of Plane ◽  
Current Value

The time and annealing temperature for the film crystallization in perovskite solar cells (PSCs) is critical and is at the stake of device optimization. It governs the crystallization process, the film’s morphorlogy and texture and the level of non-radiative defects, which in whole control the power conversion efficiency (PCE). However, deciphering each of these parameters in the device cell characteristics remains not totally clear. In this work, we led a holistic study considering temperature and time for the MAPbI3 crystallization as a free parameter to study how the latter is impacting on the film’s characteristics and how the device figure of merit is affected. The results suggest that the crystallinity level of the grains plays an important role in the photo-current value whereas the morphology and PbI2 impurities resulting from the onset of thermal decomposition of MAPbI3 penalizes the cell photovoltage and the fill factor values. Based on this study, it is highlighted that flash high temperature annealing is beneficial to limit out-of-plane substrate grain boundaries, resulting in a device exhibiting 18.8% power conversion efficiency compared to 18.0% when more standard post-annealing procedure is employed.

Metalized Polypropylene Film in Capacitors: Characterization and The Effect of Interfacial Pressure on the Dielectric Strength

1997 ◽  
Vol 476 ◽  
Author(s):  
Shalabh Tandon ◽  
Richard J. Farris
Keyword(s):  
Thermal Expansion ◽  
Energy Density ◽  
Dielectric Breakdown ◽  
Coefficient Of Thermal Expansion ◽  
Dielectric Strength ◽  
High Energy ◽  
High Energy Density ◽  
Polypropylene Film ◽  
Interfacial Pressure ◽  
Out Of Plane

AbstractMetalized polypropylene film used in high energy density capacitors has been mechanically characterized to determine its elastic constants. The out of plane coefficient of thermal expansion (CTE) of the orthotropic film is 10 times as large as the smaller in plane CTE. The out of plane modulus is twice as large compared to one of the in plane moduli. The effect of interfacial pressure on the dielectric breakdown is also studied for the same film. It is observed that the dielectric strength of the film decreases at first and then increases above 4 MPa of compressive stress.

Reliability Analysis of Flip Chip Designs Via Computer Simulation

2000 ◽  
Vol 122 (3) ◽  
pp. 214-219 ◽  
Author(s):  
Hua Lu ◽  
C. Bailey ◽  
M. Cross
Keyword(s):  
Material Properties ◽  
Flip Chip ◽  
Thermal Loading ◽  
Coefficient Of Thermal Expansion ◽  
Empirical Relationship ◽  
Life Time ◽  
Fatigue Reliability ◽  
Chip Design ◽  
Flip Chips ◽  
Out Of Plane

A flip chip component is a silicon chip mounted to a substrate with the active area facing the substrate. This paper presents the results of an investigation into the relationship between a number of important material properties and geometric parameters on the thermal-mechanical fatigue reliability of a standard flip chip design and a flip chip design with the use of microvias. Computer modeling has been used to analyze the mechanical conditions of flip chips under cyclic thermal loading where the Coffin-Manson empirical relationship has been used to predict the life time of the solder interconnects. The material properties and geometry parameters that have been investigated are the Young’s modulus, the coefficient of thermal expansion (CTE) of the underfill, the out-of-plane CTE CTEz of the substrate, the thickness of the substrate, and the standoff height. When these parameters vary, the predicted life-times are calculated and some of the features of the results are explained. By comparing the predicted lifetimes of the two designs and the strain conditions under thermal loading, the local CTE mismatch has been found to be one of most important factors in defining the reliability of flip chips with microvias. [S1043-7398(00)01203-2]

scholarly journals Stability Study of an Electrothermally-Actuated MEMS Mirror with Al/SiO2 Bimorphs

Micromachines ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 693 ◽  
Author(s):  
Peng Wang ◽  
YaBing Liu ◽  
Donglin Wang ◽  
Huan Liu ◽  
Weiguo Liu ◽  
...  
Keyword(s):  
Fill Factor ◽  
Microelectromechanical Systems ◽  
Stability Study ◽  
Driving Voltage ◽  
Electrothermal Actuation ◽  
Different Temperatures ◽  
Dynamic Scan ◽  
Bimorph Actuators ◽  
The Stability

Electrothermal actuation is one of the main actuation mechanisms and has been employed to make scanning microelectromechanical systems (MEMS) mirrors with large scan range, high fill factor, and low driving voltage, but there exist long-term drifting issues in electrothermal bimorph actuators whose causes are not well understood. In this paper, the stability of an Al / SiO 2 bimorph electrothermal MEMS mirror operated in both static and dynamic scan mode has been studied. Particularly, the angular drifts of the MEMS mirror plate were measured over 90 h at different temperatures in the range of 50 – 150 °C. The experiments show that the temporal drift of the mirror plate orientation largely depends on the temperature of the electrothermal bimorph actuators. Interestingly, it is found that the angular drift changes from falling to rising as the temperature increases. An optimal operating temperature between 75 °C to 100 °C for the MEMS mirror is identified. At this temperature, the MEMS mirror exhibited stable scanning with an angular drift of less than 0.0001 °/h.

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