Devices for fatigue testing of electroplated nickel (MEMS)

Larsen, Kim Lambertsen; Ravnkilde, Jan Tue; Ginnerup, Morten; Hansen, Ole

doi:10.1109/memsys.2002.984298

Cited by 16 publications

(11 citation statements)

References 13 publications

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“…19 was produced to test the fatigue properties of electroplated nanocrystalline (50-100 nm) nickel. 80,81 The device used an electrostatic actuator to displace a test beam with a gauge thickness of 7 µm thick, with a tapered width of 2.0-3.5 µm from bottom to top. This taper was due to the manufacturing process.…”

Section: Fatigue In Foils and Filmsmentioning

confidence: 99%

A review of deformation and fatigue of metals at small size scales

Connolley

McHugh

Bruzzi

2005

Fatigue Fract Eng Mat Struct

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A B S T R A C T Mechanical devices are being introduced whose size scale is well below that of conventional mechanical test specimens. The smallest devices have sizes in the nanometer range, though a good proportion of structural devices are of the micrometer scale. Development of these products raises the question of how their mechanical behaviour and reliability may be predicted. Conventional macroscopic test data can be used, but these are obtained using specimens whose size is much larger than the devices themselves. There is a risk that performance predictions will be inaccurate, due to the existence of size effects. This paper covers small size scale testing in metallic specimens and devices, concentrating on freestanding specimens. To begin, some examples of micro-scale devices are given. Fabrication methods for small metallic devices are then briefly described. This is followed by a review of experimental observations of mechanical properties in various metallic materials at the micro-scale, highlighting the differences in results from different research groups and the gaps in our current knowledge. A section on computational and predictive modelling is included, in recognition of the role of modelling in device design and testing. Overall, the findings are that size effects are common, particularly in crystalline samples when the grain size is similar to one or more of the specimen dimensions. However, observations of size effects differ between studies and mechanical properties can vary widely, even for the same type of material. As a consequence, the relationships between specific device processing methods, specimen size and material properties must be adequately understood to ensure successful performance. N O M E N C L A T U R EA = geometric texture factor b = Burgers vector magnitude d = grain diameter D f = fatigue ductility parameter E = elastic modulus h = film, foil or specimen thickness k = 'locking parameter,' representing the relative hardening contribution of grain boundaries K = constant for power law creep k B = Boltzmann constant l = specimen length n = Creep exponent for power law creep N f = number of cycles to failure p = constant in the Basquin and Coffin-Manson relationships

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Section: Fatigue In Foils and Filmsmentioning

confidence: 99%

A review of deformation and fatigue of metals at small size scales

Connolley

McHugh

Bruzzi

2005

Fatigue Fract Eng Mat Struct

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“…High‐density micro connectors with smaller pitch 1 and electromagnetic relay devices 2 have been manufactured by electroplating process with a UV thick photoresist. However, the little available information about the mechanical properties of electroplated Ni, compared to silicon‐based materials, prevents prediction of the mechanical reliability for long‐term usage of Ni‐based MEMS 3–5 . In order to realize optimum designs and extend the practical use of Ni‐based MEMS, mechanical characterization of electroplated Ni samples on a micrometer scale is essential.…”

Section: Introductionmentioning

confidence: 99%

“…However, the little available information about the mechanical properties of electroplated Ni, compared to silicon-based materials, prevents prediction of the mechanical reliability for long-term usage of Ni-based MEMS. [3][4][5] In order to realize optimum designs Correspondence: Y. Lee. E-mail: lyv23002@se.ritsumei.ac.jp and extend the practical use of Ni-based MEMS, mechanical characterization of electroplated Ni samples on a micrometer scale is essential.…”

Section: Introductionmentioning

confidence: 99%

Mechanical characterization of single crystal silicon and UV‐LIGA nickel thin films using tensile tester operated in AFM

Lee

Tada

Isono

2005

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper describes the mechanical characteristics of microscale single crystal silicon (SCS) and UV-LIGA nickel (Ni) films used for microelectromechanical systems (MEMS). A compact tensile tester, operated in an atomic force microscope (AFM), was developed for accurate evaluation of Young's modulus, tensile strain and tensile strength of microscale SCS and UV-LIGA Ni specimens. SCS specimens with nominal dimensions of 20 µm in thickness, 50 µm in width and 600 µm in length were prepared by a conventional photolithography and etching process. UV-LIGA Ni specimens, with a thickness of 15 µm, a width of 50 µm and a length of 600 µm in nominal dimensions, were also fabricated by electroplating using a UV thick photoresist mould. All specimens have line patterns on their specimen gauge section to measure axial elongation under tensile loading. The SCS specimens showed a linear stress-strain response and fractured in a brittle manner, whereas the UV-LIGA Ni specimens showed elastic-inelastic deformation behaviour. Young's modulus of SCS and UV-LIGA Ni specimens obtained from tensile tests averaged 169.2 GPa and 183.6 GPa, respectively, close to those of bulk materials. However, the tensile strength of both materials showed a larger value than the bulk materials: 1.47 GPa for the SCS and 0.98 GPa for the Ni specimens. Yield stress and breaking elongation of UV-LIGA Ni specimens were also quite different from those of the bulk Ni because of the specimen size effect on inelastic properties.

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“…However, with even slight perturbations, these forces will become very asymmetric, leading to the buckling of the support springs. In order to improve the reliability and to minimize device losses, significant research has been performed to investigate device failure [18]. Using closed-loop control methods to avoid the failure that causes device characteristics shifts is the most promising way to increase MEMS reliability.…”

Section: Mechanical Instabilitiesmentioning

confidence: 99%

“…Although process control is important to the development of MEMS devices, applying control schemes to MEMS itself has lagged in development, compared to other areas of MEMS development such as fabrication and structure design. To date, except for a few successes in vertical motion control, most MEMS control efforts are in simulation or theoretical analysis stages [18][19][20][21][22][23][24][25][26][27][28].…”

Section: Mems Controlmentioning

confidence: 99%

Modeling and real-time feedback control of MEMS device

Wang¹

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Modeling and Real-Time Feedback Control of MEMS Device Limin Wang Applying closed-loop control to a MEMS devices not only can handle the abnormal behaviors caused by manufactory imprecision or device failure, enabling MEMS devices to survive in critical conditions, but also can increase the application where MEMS devices are used to drive components under varying load conditions. This study mainly focuses on the effort of closed-loop control on the Lateral Comb Resonator (LCR) MEMS device. The success of closed-loop control has been achieved on lateral comb resonator with novel integrated through wafer optical monitoring technique [1]. Availability of a system model and feedback signals are mandatory conditions for the implementation of closed-loop control. Because of the fabrication process tolerance, the parameters of the Lateral Comb Resonator (LCR)'s model, especially the damping parameterβ, cannot be determined accurately based merely on theoretical analysis. Therefore, performing system identification through experiments can be a tool to verify the system model. Three different system identification methods in both the time domain and frequency domain have been implemented, and the results agree. Noise analysis on the optical monitoring signal shows that at least 90% of the noise in the signal is due to the optical monitoring setup, and the simulation shows that both a wavelet thresholding method and frequency domain low pass filter are efficient in removing this Gaussian distributed noise. Different designs are developed to monitor the LCR, both for single opening and grating structure LCRs, resulting in monitoring signals that are very different in nature. The optical monitoring signal for single opening device is highly correlated with the LCR's shuttle position. After removing the noise, this signal can be used directly as a feedback signal to perform closed-loop control on the shuttle for damping shock effect or to perform stroke-length control on the shuttle [2]. The optical monitoring signal for the grating structure LCR is a kind of frequency modulation of the shuttle's displacement. Based on this signal, both position and velocity signals can be reconstructed in real time [1,3]. Even though the reconstructed position and velocity signals will inherit and even amplify all the noises that exists in the optical monitoring signal, with this method acceptable performance has been achieved in the tracking control experiment of the LCR's shuttle. In this experiment, the newly designed model reference adaptive fuzzy sliding controller (MFSC) effectively minimized the side effects caused by either signal noise or imprecision of the system model. Furthermore, experimental success on force estimation has been achieved based on this signal reconstruction method [4]. The signal reconstruction method, which can decouple the noise from the optical signal, has been implemented. 2µm's resolution can be achieved with the current single beam optical monitoring method. The resolution can be improved several times with...

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Devices for fatigue testing of electroplated nickel (MEMS)

Cited by 16 publications

References 13 publications

A review of deformation and fatigue of metals at small size scales

A review of deformation and fatigue of metals at small size scales

Mechanical characterization of single crystal silicon and UV‐LIGA nickel thin films using tensile tester operated in AFM

Modeling and real-time feedback control of MEMS device

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