Design and manufacturing of X-band RF MEMS switches

Microsystem Technologies - In this article, we present the results of the design of different geometries for X-band RF MEMS switches. A number of mechanical and RF optimizations are described along...     

Design of meander line inductors on printed circuit boards

A partial‐element circuit model for meander line inductors printed on circuit boards is proposed and its relation with the physical layout is derived. A procedure for the design is presented allowing to obtain inductances between 8 and 50 nH in the range from 30 to 1000 MHz with a 5% mean error. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 219–230, 2001.     

Automatic inspection system for printed circuit boards

The purpose of this correspondence is to present problems and methods in automating visual inspection of printed circuit boards (PCB's). Vertical and diagonal illumination are useful in detecting PCB patterns correctly. An algorithm comparing local features of the patterns to be inspected with those of the pattern to be referenced is proposed. An inspection system using developed technologies is also described.     

Experiments with routing on printed circuit boards

Several ways of utilizing Lee's wave algorithm for routing on printed circuit boards were compared. It was proved that the order of net processing influenced the quality of the solution of a given interconnection problem. Moreover, it was found that the choice of ‘source’ and ‘target’ formations influenced both the computational time and the quality of the solution. The results obtained allowed the performance of the SYSDEB77 system for routing on two-layer boards to be improved.     

Prerouting analysis of printed circuit boards

Several methods used for the prerouting analysis of printed circuit boards are compared. The quality of a method is expressed as the correlation between predicted and actual values of objective measures of an interconnection problem complexity. The experimental data confirm that some indicators of a board complexity which are often used in practice, such as component density, are highly unreliable. The PAP program is based on the modelling of the actual routing process. It has been experimentally proved that the PAP program provides reliable results which can be used for the detailed analysis of an interconnection problem.     

Electromechanical model of RF MEMS switches

With the recent rapid growth of Radio Frequency Micro-Electro-Mechanical Systems (RF MEMS) switches, there has developed an emergent requirement for more accurate theoretical models to predict their electromechanical behaviors. Many parameters exist in the analysis of the behavior of the switch, and it is inconvenient for further study. In this paper, an improved model is introduced, considering simultaneously axial stress, residual stress, and fringing-field effect of the fixed-fixed bridge structure. To avoid any unnecessary repetitive model tests and numerical simulation for RF MEMS switches, some dimensionless numbers are derived by making governing equation dimensionless. The electromechanical behavior of the fixed-fixed bridge structure of RF MEMS switches is totally determined by these dimensionless numbers.The supports from the Key Project from the Chinese Academy of Sciences (No. KJCX2-SW-L2), projects from the NSFC (Nos 19928205, No. 50131160739 and No. 10072068), and the National 973 Project (Grant No. G1999033103) are gratefully acknowledged. The authors would like to thanks Prof. Yilong Hao of Institute of Microelectronics, Peking University, for helpful discussion.     

RF MEMS membrane switches on GaAs substrates for X-band applications

Micromechanical switches have demonstrated great potential at microwave frequencies. For low-loss applications at microwave frequencies, it is important to use high-resistivity substrates. This paper presents the design and fabrication of the shunt-capacitive MEMS switch on GaAs substrates. Analytical mechanical and impedance models of the membrane switch are given, and the results are confirmed by using the ANSYS and HFSS software, respectively. A surface micromachining process, which is compatible with the conventional millimeter-wave integrated circuits (MMICs) fabrication technology, was adopted to fabricate the RF switch on GaAs substrates. Its S-parameter was taken using a HP8510C vector network analyzer and a Cascade Probe station. The measured insertion loss of the switch and its associated transmission line is less than 0.25 dB from 1 to 25.6 GHz, and the isolation may reach -42 dB at its self-resonate frequency of 24.5 GHz. The actuation voltage is about 17 V. The switch has demonstrated lifetimes as long as 5/spl times/10/sup 6/ cycles. The wideband high performance in isolation and insertion loss offers the monolithic integration capability with GaAs MMICs.     

Artwork production for multi-layer printed circuit boards by computer

This paper describes a computer system which integrates three types of numerical control machines in the production of artwork drawings and drill tapes for multi-layer printed circuit boards.     

Inspection of printed circuit boards by connectivity preservingshrinking

Two algorithms for visual inspection of printed-circuit boards are presented that perform width checking of conductors and insulators. The first detects the difference between the results of shrinking and connectivity-preserving shrinking (CPS). The second algorithm produces a difference between the original and the shrunk picture. This result is subject to a number of CPS-operations after which errors are easily detected. Both algorithms can be adapted to a suitable level of sensitivity to sharp corners and edge irregularities. A sequential version of CPS is also described which is well suited for hardware implementation in a pipelined structure     

Mechanical modelling of capacitive RF MEMS shunt switches

The mechanical response of a RF MEMS shunt connected switch in coplanar waveguide configuration has been studied by using both an uni-dimensional approach based on analytical equations and a Finite Element Method (FEM) with commercial software simulations. The analytical model, developed by means of a MATHCAD program, has been used to predict the dynamics of the device, mainly taking into account its re-configuration time and the energy balance involved in the actuation and in the de-actuation mechanisms. After that, 2D and 3D simulations have been performed to get the really deformed shape of the bridge, depending on the central and lateral actuation of the suspended beam. After that, 2D and 3D simulations have been performed by a central and lateral actuation of the suspended beam to get the really deformed shape of the bridge. Theoretical and experimental results about the threshold voltage and the response time of the device confirm the validity of the proposed modeling.     

A solution technique for placing digital integrated circuitry on printed circuit boards

A mathematical formulation of the problem is presented using the concepts and terminology of graph theory. This formulation includes both stages of the placement problem wherein the vertices of the circuit graph are partitioned into several subsets (representing integrated circuit packages) which are, in turn, assigned to geometric positions corresponding to the printed circuit board specifications. Utilizing the manhattan metric, a heuristic procedure is described which provides minimum length placements on two-sided printed circuit boards consistent with the requirements of PC board designers. Computational results from problems arising in actual design efforts are discussed.     

An evolutionary design methodology of printed circuit boards for high-speed VLSIs

As operation frequencies of the printed circuit boards (PCBs) increase in keeping with VLSI frequencies in the GHz domain, two independent serious problems occur in the PCB design. One is waveform distortion problem, or signal integrity (SI) degradation problem, in PCB traces. And the other is power-supply drop problem, or power integrity (PI) degradation problem, in PCB power planes. Those problems are barely able to be overcome on case-by-case empirical designs conventionally. In this paper we newly propose a design approach for each problem, both of which are based on the genetic algorithm. And we obtained improvement ratios of more than double compared with the both conventional designs for SI and PI degradations, respectively.     

On characterization of symmetric type capacitive RF MEMS switches

Microsystem Technologies - This paper presents the design, fabrication and characterization of capacitive type MEMS switch for space and terrestrial communication applications. The deviation in...     

Modeling and characterization of an industrial inkjet head for micro-patterning on printed circuit boards

A conceptual design using computational fluid dynamics (CFD) and micro-electro-mechanical systems (MEMS) fabrication has been performed to develop an industrial inkjet head for micro-patterning on printed circuit boards. The printhead has been fabricated with silicon and silicon on insulator (SOI) wafers by MEMS process and silicon to silicon bonding method. The measured displacement waveform from a piezoelectric actuator by laser doppler vibrometer (LDV) was used as input data for the three-dimensional flow solver to simulate the droplet formation. The mechanism of droplet ejection from piezoelectric-type inkjet heads was investigated by simulating two-phase flows of the air and metal inks. As a preliminary approach, liquid metal jetting phenomena are identified by simulating droplet ejection and droplet formation in a consequent manner. Parametric studies are followed by the design optimization process to deduce key factors to inkjet head performance: nozzle geometry, droplet size, ejecting speed, pulse amplitude, and ink viscosity. The present design tool, based on a two-phase flow solver and experimental measurements, has shown its promising applicability to various concept designs of industrial inkjet system for micro-patterning on electronic chips and boards.