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arXiv2007

Influence of Micro-Cantilever Geometry and Gap on Pull-in Voltage

In this paper, we study the behaviour of a microcantilever beam under electrostatic actuation using finite difference method. This problem has a lot of applications in MEMS based devices like accelerometers, switches and others. In this paper, we formulated the problem of a cantilever beam with proof mass at its end and carried out the finite difference solution. we studied the effects of length, width, and the gap size on the pull-in voltage using data that are available in the literature. Also, the stability limit is compared with the single degree of freedom commonly used in the earlier literature as an approximation to calculate the pull-in voltage.

cs.OH↗

arXiv2007

Design and Development of Novel Electroplating Spring Frame Mems Structure Specimens for the Microtensile Testing of Thin Film Materials

Microelectromechanical systems (MEMS) technologies are developing rapidly with increasing study of the design, fabrication and commercialization of microscale systems and devices. Accurate mechanical properties are important for successful design and development of MEMS. We have demonstrated here a novel electroplating spring frame MEMS Structure Specimen integrates pin-pin align holes, misalignment compensate spring structure frame, load sensor beam and freestanding thin film. The specimen can be fit into a specially designed microtensile apparatus which is capable of carrying out a series of tests on sub-micro scale freestanding thin films.

cs.OH↗

arXiv2007

Characterisation of the Etching Quality in Micro-Electro-Mechanical Systems by Thermal Transient Methodology

Our paper presents a non-destructive thermal transient measurement method that is able to reveal differences even in the micron size range of MEMS structures. Devices of the same design can have differences in their sacrificial layers as consequence of the differences in their manufacturing processes e.g. different etching times. We have made simulations examining how the etching quality reflects in the thermal behaviour of devices. These simulations predicted change in the thermal behaviour of MEMS structures having differences in their sacrificial layers. The theory was tested with measurements of similar MEMS devices prepared with different etching times. In the measurements we used the T3Ster thermal transient tester equipment. The results show that deviations in the devices, as consequence of the different etching times, result in different temperature elevations and manifest also as shift in time in the relevant temperature transient curves.

cs.OH↗

arXiv2007

The Effects of Additives on the Physical Properties of Electroformed Nickel and on the Stretch of Photoelectroformed Nickel Components

The process of nickel electroforming is becoming increasingly important in the manufacture of MST products, as it has the potential to replicate complex geometries with extremely high fidelity. Electroforming of nickel uses multi-component electrolyte formulations in order to maximise desirable product properties. In addition to nickel sulphamate (the major electrolyte component), formulation additives can also comprise nickel chloride (to increase nickel anode dissolution), sulphamic acid (to control pH), boric acid (to act as a pH buffer), hardening/levelling agents (to increase deposit hardness and lustre) and wetting agents (to aid surface wetting and thus prevent gas bubbles and void formation). This paper investigates the effects of some of these variables on internal stress and stretch as a function of applied current density.

cs.OH↗

arXiv2007

A Novel Contact Resistance Model of Anisotropic Conductive Film for FPD Packaging

In this research, a novel contact resistance model for the flat panel display (FPD) packaging based on the within layer parallel and between layers series resistance concepts was proposed. The FJ2530 anisotropic conductive films (ACF) by Sony Inc. containing the currently smallest 3micron conductive particles was used to conduct the experiments to verify the accuracy of the proposed model. Calculated resistance of the chip-on-glass (COG) packaging by the proposed model is 0.163Ω. It is found that the gold bump with 0.162Ωresistance play the major role of the overall resistance. Although the predicted resistance by the proposed model is only one third of the experimentally measured value, it has been three-fold improvement compared to the existing models.

cs.OH↗

arXiv2007

Measurement Technique for Elastic and Mechanical Properties of Polycrystalline Silicon-Germanium Films Using Surface Acoustic Waves and Projection Masks

Using Rayleigh surface acoustic waves (SAW), the Young's modulus, the density and the thickness of polycrystalline Silicon-Germanium (SiGe) films deposited on silicon and SiO2 were measured, in excellent agreement with theory. The dispersion curve of the propagating SAW is calculated with a Boundary Element Method (BEM)-Model based on Green's functions. The propagating SAW is generated with a nanosecond laser in a narrowband scheme projecting stripes from a mask on the surface of the sample. For this purpose a glass mask and a liquid crystal display (LCD) mask are used. The slope of the SAW is then measured using a probe beam setup. From the wavelength of the mask and the frequency of the measured SAW, the dispersion curve is determined point by point. Fitting the BEM-Model to the measured nonlinear dispersion curve provides several physical parameters simultaneously. In the present work this is demonstrated for the Young's modulus, the density and the thickness of SiGe films. The results from the narrowband scheme measurement are in excellent agreement with separated measurements of the thickness (profilometer), the density (balance) and the Young's modulus (nanoindenter).

cs.OH↗

arXiv2007

Effect of Surface Finish of Substrate on Mechanical Reliability of in-48SN Solder Joints in Moems Package

Interfacial reactions and shear properties of the In-48Sn (in wt.%) ball grid array (BGA) solder joints after bonding were investigated with four different surface finishes of the substrate over an underlying Cu pad: electroplated Ni/Au (hereafter E-NG), electroless Ni/immersion Au (hereafter ENIG), immersion Ag (hereafter I-Ag) and organic solderability preservative (hereafter OSP). During bonding, continuous AuIn2, Ni3(Sn,In)4 and Cu6(Sn,In)5 intermetallic compound (IMC) layers were formed at the solder/E-NG, solder/ENIG and solder/OSP interface, respectively. The interfacial reactions between the solder and I-Ag substrate during bonding resulted in the formation of Cu6(Sn,In)5 and Cu(Sn,In)2 IMCs with a minor Ag element. The In-48Sn/I-Ag solder joint showed the best shear properties among the four solder joints after bonding, whereas the solder/ENIG solder joint exhibited the weakest mechanical integrity.

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arXiv2007

Non Linear Techniques for Increasing Harvesting Energy from Piezoelectric and Electromagnetic Micro-Power-Generators

Non-linear techniques are used to optimize the harvested energy from piezoelectric and electromagnetic generators. This paper introduces an analytical study for the voltage amplification obtained from these techniques. The analytical study is experimentally validated using a macro model of piezoelectric generator. Moreover, the integration influences on these techniques is studied. Through all the obtained results, a suitable structure for autonomous microsystems is proposed.

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arXiv2007

Optimization of Piezoelectric Electrical Generators Powered by Random Vibrations

This paper compares the performances of a vibrationpowered electrical generators using PZT piezoelectric ceramic associated to two different power conditioning circuits. A new approach of the piezoelectric power conversion based on a nonlinear voltage processing is presented and implemented with a particular power conditioning circuit topology. Theoretical predictions and experimental results show that the nonlinear processing technique may increase the power harvested by a factor up to 4 compared to the Standard optimization technique. Properties of this new technique are analyzed in particular in the case of broadband, random vibrations, and compared to those of the Standard interface.

cs.OH↗

arXiv2007

Power Processing Circuits for Mems Inertial Energy Scavengers

Inertial energy scavengers are self-contained devices which generate power from ambient motion, by electrically damping the internal motion of a suspended proof mass. There are significant challenges in converting the power generated from such devices to useable form, particularly in micro-engineered variants. This paper presents approaches to this power conversion requirement, with emphasis on the cases of electromagnetic and electrostatic transduction.

cs.OH↗

arXiv2007

Motion-Based Generators for Industrial Applications

Scaling down of electronic systems has generated a large interest in the research on miniature energy sources. In this paper a closer look is given to the use of vibration based scavengers in industrial environments, where waste energy is abundantly available as engine related vibrations or large amplitude motions. The modeling of mechanical generators resulted in the design and realization of two prototypes, based on electromagnetic and electrostatic conversion of energy. Although the prototypes are not yet optimized against size and efficiency, a power of 0.3 mW has been generated in a 5 Hz motion with a 0.5 meter amplitude.

cs.OH↗

arXiv2007

Design and Fabrication of a Micro Electrostatic Vibration-to-Electricity Energy Converter

This paper presents a micro electrostatic vibration-toelectricity energy converter. For the 3.3 V supply voltage and 1cm2 chip area constraints, optimal design parameters were found from theoretical calculation and Simulink simulation. In the current design, the output power is 200 $μ$W/cm2 for the optimal load of 8 MΩ. The device was fabricated in a silicon-on-insulator (SOI) wafer. Mechanical and electrical measurements were conducted. Residual particles caused shortage of the variable capacitor and the output power could not be measured. Device design and fabrication processes are being refined.

cs.OH↗

arXiv2007

Macro and Micro Scale Electromagnetic Kinetic Energy Harvesting Generators

This paper is concerned with generators that harvest electrical energy from the kinetic energy present in the sensor nodes environment. These generators have the potential to replace or augment battery power which has a limited lifetime and requires periodic replacement which limits the placement and application of the sensor node.

cs.OH↗

arXiv2007

Impact of Thermal Behavior on Offset in a High-Q Gyroscope

In this paper, CFD approach is used to simulate the thermal behavior in a sensitive high-Q gyroscope. The electromagnetically driving wires, in which AC current flows, are treated as Joule heat sources in the model. We found that the differences of temperature, pressure and velocity along the driving direction and transversely across the proof masses increased as the gap height between the proof mass and top glass became smaller. Local pressure gradient is expected to possibly enhance the impact of any imperfect led by MEMS processes or designs on the offset of our tuning fork type gyroscope, which has been experimentally verified. A device with 200um gap gives a two-third offset down compared with that of its counterpart with 50um gap.

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arXiv2007

Scaling Effects for Electromagnetic Vibrational Power Generators

This paper investigates how the power generated by electromagnetic based vibrational power generators scales with the dimension of the generator. The effects of scaling on the magnetic fields, the coil parameters and the electromagnetic damping are presented. An analysis is presented for both wire-wound coil technology and micro-fabricated coils.

cs.OH↗

arXiv2007

A Generic Surface Micromachining Module for Mems Hermetic Packaging at Temperatures Below 200 degrees C

This paper presents the different processing steps of a new generic surface micromachining module for MEMS hermetic packaging at temperatures around 180 degrees C based on nickel plating and photoresist sacrificial layers. The advantages of thin film caps are the reduced thickness and area consumption and the promise of being a low-cost batch process. Moreover, sealing happens by a reflow technique, giving the freedom of choosing the pressure and atmosphere inside the cavity. Sacrificial etch holes are situated above the device allowing shorter release times compared to the state-of-the-art. With the so-called over-plating process, small etch holes can be created in the membrane without the need of expensive lithography tools. The etch holes in the membrane have been shown to be sufficiently small to block the sealing material to pass through, but still large enough to enable an efficient release.

cs.OH↗

arXiv2007

A Ku-Band Novel Micromachined Bandpass Filter with Two Transmission Zeros

This paper presents a micromachined bandpass filter with miniature size that has relatively outstanding performance. A silicon-based eight-order microstrip bandpass filter is fabricated and measured. A novel design method of the interdigital filter that can create two transmission zeros is described. The location of the transmission zeros can be shifted arbitrarily in the stopband. By adjusting the zero location properly, the filter provides much better skirt rejection and lower insertion loss than a conventional microstrip interdigital filter. To reduce the chip size, through-silicon-substrate-via-hole is used. Good experimental results are obtained.

cs.OH↗

arXiv2007

The Design and Fabrication of Platform Device for Dna Amplification

Thermalcycler were extensively used machine for amplify DNA sample. One of the major problems in the working time was that it spent most of time for cooling and heating. In order to improve the efficient, this study presented a novel method for amplify DNA sample. For this concept, the DNA sample in the silicon chamber which was pushed by a beam through three temperature regions around a center and then the DNA segments could be amplified rapidly after 30 cycles. The polymerase chain reaction platform was composed of thin-film heaters, copper plates, DC powers, and temperature controllers. The photolithography and bulk etching technologies were utilized to construct the thin-film heater and DNA reaction chambers. Finally, 1 pound gL 100bp DNA segment of E. coli K12 was amplified successfully within 36 minutes on this PCR platform.

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