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Tilmans H.A.C. van de Peer D.J. Beyne E. 《Journal of microelectromechanical systems》2000,9(2):206-217
A variety of microelectromechanical system devices requires encapsulation of their crucial fragile parts in a hermetically sealed cavity for reasons of protection. Hermeticity of the cavity and controllability of the ambient (gas pressure and gas composition) can be critical to the device performance. In order to minimize damage during handling, the cavity is preferably realized at the same time the device is fabricated, i.e., at wafer level. This paper reports the development of a hermetic packaging technique satisfying all the above. The method is referred to as the indent-reflow-sealing (IRS) technique, which relies on a multiple-chip fluxless solder-based joining technique and seal. Key process steps are the creation of an indent in the solder, the plasma pretreatment of the bonding surfaces, the pre-bonding (or sticking) of the chips and, the closing of the indent during a low-temperature (220°C-350°C) solder reflow in a clean controlled ambient using a designated oven. As opposed to other methods, the IRS method allows a greater flexibility with respect to the choice of the sealing gas and pressure, thereby offering a very hermetic seal and compatibility with low-cost high-throughput batch fabrication techniques. Flip-chip assemblies based on SnPb (67/37) solder and Au as the top surface metallization, have been reflowed in a forming gas ambient and have next been characterized on shear strength, hermeticity, and susceptibility to thermal stresses. The method has been successfully implemented in the process flow of an electromagnetic microrelay for the realization of the cavity housing the electrical contacts 相似文献
2.
Carchon G.J. Jourdain A.. Vendier O.. Schoebel J.. Tilmans H.A.C. 《Advanced Packaging, IEEE Transactions on》2007,30(3):369-376
This paper reports on the development and optimization of 0/1-level packaged coplanar waveguide (CPW) lines and radio-frequency microelectromechanical systems (RF-MEMS) switches up to millimeter-wave frequencies. The 0-level package consists of an on-chip cavity obtained by flip-chip mounting a capping chip over the RF-MEMS device using BenzoCyclobutene (BCB) as the bonding and sealing material. The 0-level coplanar RF feedthroughs are implemented using BCB as the dielectric; gold stud-bumps and thermocompression are used for realizing the 1-level package. The 0-level packaged switches have been flip-chip mounted on a multilayer thin-film interconnect substrate using a high-resistivity Si carrier with embedded passives and substrate cavities. The insertion loss of a single 0/1-level transition is below -0.15 dB at 50 GHz. The measured return loss of a 0/1-level packaged 50-Omega CPW line remains better than -19 dB up to 71 GHz and better than -15 dB up to 90 GHz. It is shown that the leak rate of BCB sealed cavities depends on the BCB width, and leak rates as low as 10-11 mbar.l/s are measured for large BCB widths (> 800 mum), dropping to 10-8 mbar.l/s for BCB widths of around 100 mum. Depending on the bonding conditions, shear strengths as high as 150 MPa are achieved. 相似文献
3.
De Los Santos H.J. Fischer G. Tilmans H.A.C. van Beek J.T.M. 《Microwave Magazine, IEEE》2004,5(4):36-49
The aim of this article to expose the impact and status of the application of RF-MEMS switchable capacitors, varactors and switches in the three elements of this paradigm, namely, handsets, base stations, and satellites. In particular, issues such as system-level motivation/justification for RF MEMS, device requirements, high-volume manufacturing, packaging, and state-of-the-art performance and reliability, are presented. 相似文献
4.
Tilmans H.A.C. Legtenberg R. Schurer H. Ijntema D.J. Elwenspoek M. Fluitman J.H.J. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1994,41(1):4-6
The design, fabrication and performance of vacuum-encapsulated electrostatically driven polysilicon resonating beams, 210-510 μm long, 100 μm wide, and 1.5 μm thick, are described. The shortest beams have a fundamental frequency of 324 kHz, a gauge factor of 2400 and a quality factor of 600 at cavity pressures of 0.15 mbar. Intrinsic quality factors of 18000 were measured below 0.01 mbar 相似文献
5.
Witvrouw A. Haspeslagh L. Varela Pedreira O. De Coster J. De Wolf I. Tilmans H. A. C. Bearda T. Schlatmann B. van Bommel M. de Nooijer M.-C. Magnee P. H. C. Lous E. J. Hagting M. Lauria J. Vanneer R. van Drieenhuizen B. 《Journal of microelectromechanical systems》2010,19(1):202-214
6.
Modelling of critical fibre length and interfacial debonding in the fragmentation testing of polymer composites 总被引:1,自引:0,他引:1
Th. Lacroix B. Tilmans R. Keunings M. Desaeger I. Verpoest 《Composites Science and Technology》1992,43(4):379-387
Micro-mechanical models based on a unidimensional load transfer approximation are used to predict the critical fibre length as a function of applied strain in the fragmentation testing of polymer matrix composites. Conditions of perfect adhesion, partial debonding, and total debonding are considered in turn. Situations are identified where the critical length cannot be viewed as a material constant, i.e. where it remains strain dependent as the applied strain increases. Numerical results based on the partial debonding model are given for the critical fibre length and the extent of the debonding zone as a function of applied strain. The prediction of the total debonding model is recovered asymptotically for large strains. We find, however, that the critical length predicted by the partial debonding model can be lower than the one predicted by the total debonding model if the interfacial bond strength is sufficiently larger than the frictional shear stress. These theoretical results show that both bond strength and frictional shear stress must be taken into account in the interpretation of the fragmentation test data. 相似文献
7.
De Los Santos H.J. Fischer G. Tilmans H.A.C. van Beek J.T.M. 《Microwave Magazine, IEEE》2004,5(4):50-65
This paper reports on RF-MEMS switchable capacitors, varactors, and ohmic switch technology attribute for both base stations and handsets in realizing frequency-agile RF/wireless systems capable of serving multiple frequency bands. For the handset, this leads to a smaller footprint combined with low power consumption of the RF radio. For the base station the benefit lies in ability for reconfiguration of the air interface, which leads to high logistical savings for infrastructure vendors through a reduction in the number of product variants. Reconfigurable frequency-agile radios are a perfect addition to reconfigurable baseband processing. Both together form the basis of a realistic and reasonable approach to realize software radios. 相似文献
8.
Chengqun Gui Legtenberg R. Tilmans H.A.C. Fluitman J.H.J. Elwenspoek M. 《Journal of microelectromechanical systems》1998,7(1):122-127
The nonlinearity and hysteresis effects of the electrostatically activated voltage-driven resonant microbridges have been studied theoretically and experimentally. It is shown that in order to avoid vibration instability and hysteresis to occur, the choices of the ac and dc driving voltages and of the quality factor of a resonator, with a given geometry and choice of materials, are limited by a hysteresis criterion. The limiting conditions are also formulated as the hysteresis-free design rules. Expressions for the maximum allowable quality factor and maximum attainable figure of merit are given. Experimental results, as obtained from electrostatically driven vacuum-encapsulated low-pressure chemical-vapor deposition (LPCVD) polysilicon microbridges, are presented and show good agreement with the theory 相似文献
9.
Guckel H. Burns D.W. Visser C.C.G. Tilmans H.A.C. Deroo D. 《Electron Devices, IEEE Transactions on》1988,35(6):800-801
Novel processing conditions and strain diagnostic structures are used to demonstrate that polysilicon films with built-in tensile-strain can be achieved and that any physical size limitations due to compressive-buckling in polysilicon micromechanical structures can be eliminated 相似文献
10.
The paradigm of operant behaviour (Skinner) systematically applied to a group constitutes the theoretical basis of token-economy programs. Such a system consists in relating a certain behaviour to a consequence known to the patient. The efficiency of a token-economy has already been demonstrated for various populations: delinquants, schooolboys, chronic psychiatric patients. This pilot-study reports on our experience in applying in token-economy program in a group of young schizophrenics, most of them being hebefrenics: concepts and difficulties in realisation, hierarchical structure of the system, and results obtained. 相似文献
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