Field penetration into metallic enclosures through slots excited byESD

The coupling through apertures between an electrostatic discharge (ESD) current flowing on the external shield of a metallic enclosure and the electromagnetic field of its internal region is analyzed; the excitation of the electric field on the apertures by the ESD and then the evaluation of the internal field are calculated separately, by means of the finite difference time domain (FDTD) technique and the modal expansion, respectively. All the numerical results obtained with this simple and numerically efficient approach have been validated by measurements     

Wave penetration through bent slots

Shielding effectiveness of bent slots carved in a metal plate of finite thickness is analyzed by forming a set of integral equations based on the equivalence principle. Method of moments is used to solve the integral equations for the transmission cross sections. The effects of slot geometry, filling permittivity, and filling conductivity are studied. It is found that the penetrating field is mainly determined by the slot length, filling permittivity, and filling conductivity. Resonances are also observed when the slot length is integer multiples of half wavelengths     

Ray analysis of electromagnetic field build-up and quality factorof electrically large shielded enclosures

A high-frequency asymptotic ray solution is investigated for predicting the electromagnetic field build up and steady-state parameters of shielded enclosures or cavities, which are large with respect to wavelength. It is found that the ray solution can deterministically predict the early-time field build up after the source is switched on, but cannot predict the steady-state fields of high-Q enclosures because of the intractably large number of ray reflections required for convergence. However, it is demonstrated that the steady-state Q factor may be predicted from the early-time energy density build up at a point by coherently summing the power in each ray. The Q factor is obtained via its relationship to the cavity time constant, which may be extracted from the early time energy density curve. A clear indication of polarization diversity throughout the enclosure may also be obtained by plotting the polarization components of the early-time fields and energy density build up at different points. The advantage of the ray method is that it can be used to treat large closed cavities of relatively arbitrary shape     

Water vapor penetration rate into enclosures with known air leak rates

The rate at which water vapor penetrates a faulty seal in a "hermetically sealed" device has been examined both experimentally and theoretically in this study. The experimental data were generated by studying the rate of moisture ingress into two types of packages; a TO-5 can and a ¼ × ¼ in ceramic flatpack. The TO-5 packages were fitted with capillary tubes of varying diameters with known air leak rates and represented the gross leak range (down to 10^-5atm . cm³/s) while the ¼ × ¼ in ceramic flatpacks were used to study the fine leak range (10^-6to 10^-8atm . cm³/s). Both type packages were fitted with miniature moisture sensors (surface conductivity type) and calibrated at known relative humidities prior to sealing. The finished test packages were then exposed to constant high-humidity conditions and monitored for moisture content as a function of time. A theoretical analysis was performed by using conventional leak rate equations to convert air leak rates, at standard test conditions, to water vapor leak rates at partial pressure differentials seen typically at room ambient conditions. These data compared favorably with the experimental results in the range tested and suggests that present hermeticity specifications are too lenient for long-term reliability requirements.     

Deep field penetration into a conducting cylinder

In this paper we investigate the penetration of both E and H waves into a cylinder of arbitrary cross section (characteristic dimension L). The material of the cylinder is a nonmagnetic good conductor, and we examine the limits of deep penetration (small L/δ, where δ is the penetration depth) and small quality factor Q=(ωϵ₀/σ). These two asymptotic conditions imply a low-frequency situation, for which we derive formulas for the induced currents and associated Joule and radiation losses     

Modeling of field penetration through planes in multilayeredpackages

This paper describes a method for analyzing the field penetrating through planes in package power distribution networks. This field can cause excessive noise in the system at resonant frequencies of the package. The effect has been quantified both in the time and frequency domain and compared with measurements. General guidelines have been suggested to suppress this noise by varying the material and physical parameters of the planes     

Electromagnetic pulse (EMP) penetration through circular apertures in the frequency domain

Equations and curves are given for estimating field coupling from a normally electromagnetic pulse (EMP) incident plane wave through a circular aperture within a thin planar surface.     

Penetration through slots in conducting cylinders. Part 2: TM case

For pt.1 see ibid. vol.46, no.11, p. 1611-20. Three methods for determining the penetration through small apertures in closed conducting surfaces are outlined and their salient features discussed. These methods are designated: (1) the scatterer method; (2) the short-circuit current method; and (3) the equivalent current method. They are implemented by integral equation techniques but are amenable to differential equation or hybrid methods. Procedures for applying each method are outlined as are schemes for repairing singular equations rendered invalid by the presence of false resonances. Reasons for inaccuracies in the three methods are also delineated. Data determined for a given structure by all three methods are presented and numerical examples that illustrate important features of the methods and their relative accuracies are described. An outline is given of the integral equation formulation and numerical scheme needed to accurately determine the field that penetrates through a slot in a conducting cylinder, excited by an axially independent TM source     

HIRF penetration through apertures: FDTD versus measurements

The penetration of high-intensity radiated fields (HIRF) into conducting enclosures via apertures is an EMI issue that is relevant to all aviation. The stories are numerous, of disrupted communications, disabled navigation equipment, etc., due to the effects of EM sources external to the aircraft. Here, the FDTD method is used to predict the shielding effectiveness of conducting enclosures with apertures, and the numerical results are compared with measurements. Several issues related to the FDTD analysis of highly resonant and high-quality factor (high-Q) structures, such as windowing and acceleration techniques, are examined and discussed     

Electric-field penetration into metals: consequences forhigh-dielectric-constant capacitors

A consequence of the finite electronic screening length in metals is that electric fields penetrate short distances into the metal surface. Using a simple, semiclassical model of an idealized capacitor, we estimate the capacitance correction due to the distribution of displacement charge in the metal electrodes. We compare our result with experimental data from thin-film high-dielectric-constant capacitors, which are currently leading contenders for use in future high-density memory applications. This intrinsic mechanism contributes to the universally-seen decrease in measured dielectric constant with capacitor film thickness     

A prognostic approach for non-punch through and field stop IGBTs

Development of prognostic approaches for insulated gate bipolar transistors (IGBTs) is of interest in order to improve availability, reduce downtime, and prevent failures of power electronics. In this study, a prognostic approach was developed to identify anomalous behavior in non-punch through (NPT) and field stop (FS) IGBTs and predict their remaining useful life. NPT and FS IGBTs were subjected to electrical–thermal stresses until their failure. X-ray analysis performed before and after the stress tests revealed degradation in the die attach. The gate–emitter voltage (V_GE), collector–emitter voltage (V_CE), collector–emitter current (I_CE), and case temperature were monitored in situ during the experiment. The on-state collector–emitter voltage (V_CE(ON)) increased and the on-state collector–emitter current (I_CE(ON)) decreased during the test. A Mahalanobis distance (MD) approach was implemented using the V_CE(ON) and I_CE(ON) parameters for anomaly detection. Upon anomaly detection, the particle filter algorithm was triggered to predict the remaining useful life of the IGBT. The system model for the particle filter was obtained by a least squares regression of the V_CE(ON) at the mean test temperature. The failure threshold was defined as a 20% increase in V_CE(ON). The particle filter approach, developed using the system model based on the V_CE(ON), was demonstrated to provide mean time to failure estimates of IGBT remaining useful life with an error of approximately 20% at the time of anomaly detection.     

Transmission through dielectric-filled slots in a conductingcylindrical shell of arbitrary cross section: TE case

A simple moment solution is summarized for the problem of electromagnetic transmission through dielectric-filled slots in a conducting cylindrical shell of arbitrary cross section. The system is excited by a plane-wave polarized transverse electric (TE) to the axis of the shell. The equivalence principle is used to replace the shell and the dielectric by equivalent electric and magnetic surface currents radiating into an unbounded medium. Two different sets of coupled integral equations involving the surface currents are obtained by enforcing the boundary conditions on the tangential components of the total electric and magnetic fields. The method of moments is used to solve the integral equations. Pulses are used for both expansion and testing functions. Special attention is paid to circular and rectangular shells. Results for shell surface current, the internal field, and the aperture field are presented. For the case of air dielectric filling, the results computed using the electric field and/or the magnetic field formulation are in very good agreement with published data. In general, it is observed that the effect of filling a slot with a dielectric is not predictable from a simple theory     

Electromagnetic penetration into 2-D multiple slotted rectangularcavity: TM-wave

Electromagnetic wave penetration into the two-dimensional (2-D) rectangular cavity with multiple slots in an infinite conducting plane with a finite thickness is investigated. The Fourier transform and the mode-matching technique are used to obtain simultaneous equations, which are solved to represent the scattered and the penetrated fields in series forms that are suitable for numerical computations     

Electromagnetic penetration into 2D multiple slotted rectangularcavity: TE-wave

Electromagnetic wave penetration into a two-dimensional rectangular cavity with multiple slots in an infinite conducting plane with a finite thickness is investigated. The Fourier transform and a mode-matching technique are used to obtain simultaneous equations, which are solved to represent the scattered and penetrated fields in series forms suitable for numerical computations     

Transient electromagnetic field propagation through infinite sheets, into spherical shells, and into hollow cylinders

Gaussian electromagnetic field pulses of several durations are propagated through infinite sheets into the interior of hollow cylinders and into the interior of spherical shells. The plates, spheres and cylinders are made of aluminum and contain no slots. The time history of the propagated pulses is computed. Finally, the time sequence of the electric field is calculated in the interior of a cylinder of finite length when connected at its ends by wires to a generator delivering a current pulse of Gaussian shape. The dimensions of the cavities are assumed to be sufficiently small so that resonances are not excited by the highest significant frequency contained in the shortest pulse considered. The numerical study is restricted to thin-walled aluminum shields 1/32 inch, 1/16 inch, 1/8 inch and 1/4 inch thick. The half-amplitude widths of the pulses employed lie in the range14 musec to2400 musec. It is shown that the resultant Gaussian pulse electric fields defined on the surface of the plates and cylinders are propagated with little diminution in amplitude. This is understandable due to the requirement that the tangential fields are continuous across the interfaces, and to the fact that skin effect is almost nonexistent at low frequencies. The incident (as contrasted to resultant) field pulse undergoes reflection at the boundary surface. Hence, the attenuation sustained by the incident field is great, since reflection is the chief mechanism of attenuation of fields at low frequencies. Thin spherical shells form effective magnetic shields. The electric field is small in the interior of thin-walled cylinders carrying extremely large transient currents.     

Resonant electromagnetic field coupled into a lossy cavity through a slot aperture

A new approach is proposed for determining the electromagnetic fields coupled from an incident plane wave into a lossy conducting cavity through a slot aperture under resonant conditions. Use is made of the duality between a slot and a conducting strip and of the equivalence between a strip and a wire. Simplified formulas are derived that are explicit and flexible. Determination of resonant fields inside a cavity is reduced to simple calculations. Numerical examples are given.     

A 4H-SiC semi-super-junction shielded trench MOSFET: p-pillar is grounded to optimize the electric field characteristics

A 4H-SiC trench gate metal–oxide–semiconductor field-effect transistor (UMOSFET) with semi-super-junction shielded structure (SS-UMOS) is proposed and compared with conventional trench MOSFET (CT-UMOS) in this work. The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET. In particular, the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed. The on-resistance of SS-UMOS with grounded (G) and ungrounded (NG) p-pillar is reduced by 52% (G) and 71% (NG) compared to CT-UMOS, respectively. Additionally, gate oxide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions. Thus, a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer. However, the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar, resulting in a large electric field of 2.7 MV/cm at the gate oxide layer. Moreover, the total switching loss of GSS-UMOS is 1.95 mJ/cm² and is reduced by 18% compared with CT-UMOS. On the contrary, the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three. The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications, and will provide a valuable idea for device design and circuit applications.     

Suppression of boron penetration through thin gate oxides by nitrogen implantation into the gate electrode in PMOS devices

PMOS devices with and without nitrogen implant into the gate electrode before doping with boron and with nitridation of the gate oxide were manufactured. The influence of nitrogen on the penetration of boron ions into the substrate through ultra-thin gate oxides was investigated by electrical and SIMS measurements. Boron diffusion can be effectively prevented by high nitrogen concentrations located immediately above the gate oxide and within the polysilicon gate electrode.     

Suppression of boron penetration through thin gate oxides by nitrogen implantation into the gate electrode of PMOS devices

PMOS devices with different amounts of nitrogen implanted into the gate electrode before doping with BF₂ implantation and implant anneal were manufactured. The thicknesses of the gate oxides grown in dry oxygen by RTP were 4.1 down to 2.8 nm. The implant anneal was also performed by RTP. The influence of the nitrogen on the penetration of boron ions through the ultra-thin gate oxides into the channel region was investigated by electrical and SIMS measurements. Boron was effectively prevented from diffusion by high nitrogen concentrations at the polysilicon/gate oxide interface without degrading the reliability. In return, increased sheet resistivities and gate depletion have to be taken into account by high nitrogen concentrations within the polysilicon gate electrode.     

Spectral domain approach applied to open resonators: application tomicrostrip antennas

The correct use of the spectral domain approach for open resonators in the free regime is discussed. An application to microstrip antennas is presented