Vol.:(0123456789) 1 3 Transactions on Electrical and Electronic Materials https://doi.org/10.1007/s42341-019-00162-2 REGULAR PAPER Investigation on Dielectric Material Selection for RF‑MEMS Shunt Capacitive Switches Using Ashby, TOPSIS and VIKOR Pritam Patra 1  · Mahesh Angira 2 Received: 26 March 2019 / Revised: 4 November 2019 / Accepted: 13 November 2019 © The Korean Institute of Electrical and Electronic Material Engineers 2019 Abstract In this paper, diferent material selection techniques like Ashby, TOPSIS and VIKOR have been used to select the best dielectric material for RF-MEMS switches with low power consumption. These methods help in choosing the optimum mate- rial from the available pool of materials. The dielectric material should be selected such that RF-MEMS capacitive switch should have good RF response, high thermal conductivity, low thermal coefcient of expansion, and low leakage current. For this purpose, the concerned material indices should have high value of relative permittivity, high value of electrical resistivity, low value of thermal coefcient of expansion, and high value of thermal conductivity. The presence of trade-ofs led to no conclusive selection in case of Ashby’s method. Following Ashby’s method, TOPSIS and VIKOR method were used to select the optimum material. The end results suggest that TiO 2 is the most suitable materials for shunt capacitive RF-MEMS switches. Keywords Ashby method · Capacitive switches · Dielectric · RF-MEMS · TOPSIS · VIKOR 1 Introduction In recent years, RF-MEMS technology based switches have gained more research attention as they have superior per- formance as compared to solid-state switches (PIN-diode and FET). This is due to their capabilities of providing low insertion loss, better isolation and low power consumption. RF-MEMS switches have many applications in telecommu- nication systems such as cellular stations, mobile handsets, phase-shifters, tunable flters, SPNTs, switch matrices, etc. [1–4].There are many confgurations possible for MEMS switches, but this paper focuses on the shunt capacitive switches with low power consumption.The shunt capacitive switches act as a variable capacitor. This variable capaci- tor has two stable states. In up-state of the device, power can fow from the input port to the output port. This state corresponds to the on-state of the switch. The down-state can be achieved by actuating the hanging structures by electrostatic actuation. This state corresponds to the of- state of the device. The up-state and the down-state of the switch are shown in Fig. 1. Thus, dielectric material plays an important role in the working of RF-MEMS capacitive switches. Furthermore, RF response i.e., insertion loss and isolation characteristics of the switches is decided by the capacitance ratio, which in turn depends on the dielectric constant. The capacitance ratio and thus the dielectric con- stant should be as high as possible in order to have good RF response [5, 6]. Furthermore, selected dielectric material should have low leakage current, high heat dissipation, and low thermal expansion, which corresponds to high electrical resistivity and thermal conductivity and low coefcient of thermal expansion respectively. As the switches considered here are of low power, the parameters like thermal expan- sion and thermal conductivity have been preferred less than other two parameters. There are numerous possible dielectric materials and to select the best among them is a very tedious process and manual selection is prone to errors. Thus, material selection methodologies should be used to choose the optimum mate- rial for a particular application. Ashby, TOPSIS and VIKOR are the most commonly used Multiple Criteria Decision Mak- ing (MCDM) techniques [7–11]. These techniques facilitate accurate material selection from a pool of materials. MCDM Online ISSN 2092-7592 Print ISSN 1229-7607 * Mahesh Angira m.angira@gmail.com 1 Department of Electrical and Electronics Engineering, BITS, Pilani, Rajasthan, India 2 Electronics and Communication Engineering Department, NIT, Hamirpur, HP, India