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General Components of Machine Tool
Published in Ajay M. Sidpara, Ganesh Malayath, Micro Electro Discharge Machining, 2019
Ajay M. Sidpara, Ganesh Malayath
Figure 2.16 shows a representation of the ideal and realistic voltage and current pulses during EDM. The terminologies related to the pulse characteristics are explained as follows: Breakdown voltage: The voltage at which dielectric breakdown happens.Gap voltage: Voltage measured between the tool and the workpiece.Peak current: Maximum amplitude of current in the gap during a discharge period.Pulse ON time: The period when discharge occurs. Pulse OFF time: The period when discharge disappears and deionization of dielectric fluid starts.Ignition delay: It is the delay in time between start of a pulse and start of a discharge.
Process Variability and Reliability of Nano-Scale CMOS Analog Circuits
Published in Soumya Pandit, Chittaranjan Mandal, Amit Patra, Nano-Scale CMOS Analog Circuits, 2018
Soumya Pandit, Chittaranjan Mandal, Amit Patra
is referred to the as the relative permittivity or the dielectric constant of the material. The dielectric material for which the dielectric constant κ is a constant is referred to as the linear dielectric. If the susceptibility χ of a dielectric material does not depend on the direction of the electric field, it is referred to as an isotropic dielectric. With the application of a sufficiently high electric field, the linear relation between P̅ and ξ̅ no longer remains valid; the dielectric breaks down, which implies that the electrons are pulled out of the molecules. The material ceases to act as an insulator since the electrons torn away from the molecules become conducting. The critical electric field at which the dielectric breakdown occurs is referred to as the dielectric strength of the material. For air, the typical value of the dielectric strength is about 3 × 106V/m and for most of the solid dielectrics, it is a few times 108 – 109V/m.
Reliability
Published in Yufeng Jin, Zhiping Wang, Jing Chen, Introduction to Microsystem Packaging Technology, 2017
Yufeng Jin, Zhiping Wang, Jing Chen
Dielectric breakdown refers to the destruction of a dielectric layer, usually as a result of excessive potential difference or voltage applied. It is usually manifested as a short or leakage at the point of breakdown. As we know, the EOS/ESD can expose the dielectric layer to high voltages that will cause the dielectric breakdown. Non-EOS/ESD-related dielectric breakdowns can be classified into either an early life dielectric breakdown (ELDB) or a time-dependent dielectric breakdown (TDDB), depending on when the dielectric breakdown occurs. ELDB usually occurs at the very beginning of operation, which is highly correlated with initial defects. However, TDDB failures are usually caused by the trap/charge generated in the gate oxide during high current/voltage stress. These gradually generated trap/charges will decrease the effective thickness of the gate oxide. At a critical point the oxide heats up and allows a greater current flow. This eventually results in an electrical and thermal runaway that quickly leads to the physical destruction of the gate oxide. As the device dimension scales rapidly, the gate oxide becomes thinner. Even though the supply voltages have decreased, the trend of miniaturization and improvement in performance results in higher electric fields across gate oxide. Therefore, gate oxide reliability becomes more important.[11–14]
Design analysis of electro-adhesive mechanism for wall-climbing robot
Published in Mechanics Based Design of Structures and Machines, 2022
Ravindra Singh Bisht, Pushparaj Mani Pathak, Soraj Kumar Panigrahi
As shown in Figs. 13(a) and (b), the revised EAM samples consist of seven pairs of comb shape electrodes designed using a PCB screen printer for electro-static adhesion force testing. The test results for both the cases have been compared via. input voltages vs. generated force plots as shown in Fig. 14. As evident from the experimental results in Fig. 14, the adhesion force significantly improves by increasing seven number of comb shape electrode pairs. Although it improves the adhesion force, but it leads to electrical breakdown when the supply input receives high input voltage. The reason may be the reduction in electrode gap (dielectric breakdown) and electric conduction in dialectic also occur when subjected to high electric field (Koh, Sreekumar, and Ponnambalam 2014).