Jeremy Smallwood - Profile on Academia.edu (original) (raw)

Papers by Jeremy Smallwood

Journal of Electrostatics, Aug 1, 2017

Four surface resistance test electrodes are compared using a selection of materials under similar... more Four surface resistance test electrodes are compared using a selection of materials under similar test conditions. The results vary considerably with some materials due to variation in surface resistivity. Using a relatively uniform material two concentric ring electrodes compliant with the same standard differed in results by a factor of 1.8. Silver stripe and copper tape electrodes gave results a factor 0.4 and 0.7 compared to the reference electrode. A 2-pin electrode gave results a factor 4.7 greater. The 2 pin probe cannot be expected to give similar results to the other electrodes for materials that have variable resistivity.

Definitions and Terminology

The task of supervising an electrostatic discharge (ESD) control program is often given to person... more The task of supervising an electrostatic discharge (ESD) control program is often given to personnel from many technical and educational backgrounds. In ESD in electronics handling, the main types of concern are: spark discharges between conducting objects or materials, brush discharges between a conducting object and an insulating material, and corona discharges from sharp conducting objects and materials. Electrostatic discharges occur because of voltage differences between the objects between which the discharge occurs. In many practical cases, one of the conductors concerned may already be electrically connected to an electrical earth or can be conveniently connected to earth. In practice in ESD control, there are various types of ground that can be used. In the ESD standards IEC 61340‐5‐1:2016a and ANSI/ESD S20.20‐2014, the term grounding is used to mean any of the following: connection to electrical earth, connection to a functional earth, and connection to an equipotential bonding system.

How to Evaluate an ESD Control Program

There are two overall types of electrostatic discharge (ESD) risk that are normally controlled in... more There are two overall types of electrostatic discharge (ESD) risk that are normally controlled in an electrostatic discharge protected area: direct ESD to or from the device; and electrostatic fields that could lead to ESD to or from the device. The process of evaluating ESD risks must start with an evaluation of the ESD susceptibility of the ESD‐sensitive (ESDS) component or assembly. This chapter discusses the evaluation of process capability of ESD control program based on human body model, machine model, and charged device model. Standard ESD control precautions applying ESD control equipment address most well‐known ESD risks, but they do not necessarily address all ESD risks. Every step of processes where ESDS devices are handled should be scrutinized for possible ESD risks. The chapter provides a discussion on the evaluation of cost effectiveness and compliance of the ESD control program.

Electrostatic Discharge–Sensitive (ESDS) Devices

Fully assembled systems that include electrostatic discharge‐sensitive (ESDS), protected within a... more Fully assembled systems that include electrostatic discharge‐sensitive (ESDS), protected within an enclosure or housing that acts as an effective barrier to ESD, are normally no longer considered an ESDS device. ESD can often be modeled using a simple electronic circuit. The simple model works well for many simple situations, particularly where the source is a conductive material and a simple resistance and inductance can approximate the discharge path. In practice, the ESD waveform is as much dependent on the properties of the “load” circuit, which can be highly nonlinear, as on the source. The three main ESD sensitivity test models used in ESD susceptibility testing of electronic components are the human body model, machine model, and charged device model. This chapter presents some specific examples representing a small fraction of the wealth of research that has been done to understand ESD failures.

Damage to ElectroStatic Discharge Sensitive Electronic Devices by Changing Electrostatic Fields

This paper demonstrates that very high impedance voltage sensitive device such as MOSFET can be d... more This paper demonstrates that very high impedance voltage sensitive device such as MOSFET can be damaged due to external field changes without making contact with other conductors. A simple electronic model is proposed. A neon bulb is used as proxy for the voltage sensitive device in practical non-destructive experiments. Damage was also confirmed using real MOSFET devices.

In this paper, a model is proposed to numerically calculate the dielectrophoretic (DEP) force act... more In this paper, a model is proposed to numerically calculate the dielectrophoretic (DEP) force acting on a straight slender body in a non-uniform electric field. The induced charges are assumed to be located along the centerline of the slender body. By enforcing the boundary conditions at the interfaces of the two dielectrics, an integral equations system is obtained with the induced charge densities as unknowns. Based on the calculated induced charge densities, expressions to calculate the DEP force and torque are obtained. The calculated induced charge density of a prolate ellipsoid under a uniform electric field is compared with the analytic solution and an excellent agreement is achieved. The smaller the slenderness (the ratio of maximum radius to length of the slender body), the smaller the error is. The DEP force that a prolate ellipsoid experiences in a general electric field is numerically calculated and compared with the results obtained by the commonly accepted effective dipole moment method. The current model is expected to possess higher accuracy than the effective dipole moment method and to demand less calculation work than the Maxwell stress tensor method.

Comparison of methods of evaluation of charge dissipation from AHE soak boats

Electrical Overstress/Electrostatic Discharge Symposium, Nov 9, 2010

The charge dissipation of anodized surfaces of soak boats used in Automated Handling Equipment (A... more The charge dissipation of anodized surfaces of soak boats used in Automated Handling Equipment (AHE) were evaluated using standard and non-standard test methods. The results of tests showed considerable variation. It is concluded that some standard test methods do not give a representative measure of charge dissipation in this application.

Journal of Electrostatics, Apr 1, 2012

Electrostatic discharge charge transfer measurements in electrostatic hazard evaluation

Journal of Electrostatics, Jun 1, 2023

Electromagnetic Shielding Effectiveness of Conductive Compounds

Understanding Electrostatic Field Meter Field and Voltage Measurements from Conductors and Insulators

A simple capacitor model helps clarify measurements made using electrostatic field meters on cond... more A simple capacitor model helps clarify measurements made using electrostatic field meters on conductors at constant voltage, isolated conductors with constant charge and uniformly charged insulating surfaces. Recommendations are made for calibration of instruments for use in an ESD control program to current standards.

Qualification challenges of footwear and flooring systems

Measurement of body voltage alone can result in erroneous conclusions in qualification of footwea... more Measurement of body voltage alone can result in erroneous conclusions in qualification of footwear and flooring systems in combination with a person. Measurement uncertainties should be taken into account. We have studied the time dependency and charge generation of some footwear and flooring systems. The most significant inconsistencies of the voltage measurement are discussed in this technical paper.

Evaluating the electrostatic discharge risk between small radius objects and charged planar insulating materials

Journal of Electrostatics, 2022

ESD Shielding of Thermoformed Clam Shell Packaging

Clam shells can provide better ESD protection than shielding bags. Energy coupling in a near fiel... more Clam shells can provide better ESD protection than shielding bags. Energy coupling in a near field is generally reduced by preventing a direct connection, decreasing capacitive coupling, and increasing breakdown field strength. A properly qualified shielding bag may have unexpected weakness in ESD protection due to the low breakdown field strength.

ESD Risks of Containers Made of Conductive Compounds

ESD risk scenarios of conductive containers were assessed by using a system level test generator ... more ESD risk scenarios of conductive containers were assessed by using a system level test generator and different configurations of discharge electrodes. Energy coupling inside the container can be minimized by an applicable mechanical design. Avoidance of the direct or capacitive drain and return path mitigates energy coupling and reduces ESD risks efficiently.

Electrostatic threats in hospital environment

Uncontrolled electrostatic discharge (ESD) sources may cause unpleasant experiences as well as mo... more Uncontrolled electrostatic discharge (ESD) sources may cause unpleasant experiences as well as more serious hazards to health. We have observed surprisingly high energy ESD sources in the hospital environment. These findings are analyzed and discussed in this article. In addition, electrostatic attraction and charge relaxation of materials for medical purposes are studied and solutions are proposed.

Comparison of surface and volume resistance measurements made with standard and non-standard electrodes

Surface and volume resistance measurements made with standard electrodes are compared with variou... more Surface and volume resistance measurements made with standard electrodes are compared with various nonstandard electrodes using a reference material. Measurements were made on two resistive materials, ESD shielding bag film and pocket tape ESD control materials.

Assessment of ESD threats to electronic components and ESD control equirements

Institute of physics conference series, May 1, 2004

ABSTRACT

Comparison of ESD from metal sphere electrodes and tribocharged insulators of both polarities using two ESD probes

Journal of Electrostatics, Jun 1, 2005

ABSTRACT Electrostatic discharge (ESD) is an important source of accidental ignitions in process ... more ABSTRACT Electrostatic discharge (ESD) is an important source of accidental ignitions in process industries and damage to semiconductor electronic devices. There is a need to understand the time-varying ESD event and interaction between ESD probe and source in order to understand the important parameters in ESD measurements for evaluation of these phenomena. This paper compares measured peak current, waveform, risetime and charge transferred in ESD from charged isolated spherical conductors with and without a ground plane (spark), and triboelectrically charged polyethylene and polyamide samples (brush discharge). Measurements made using two recently developed ESD probes are compared.

Optimizing investment in ESD control

Electrical Overstress/Electrostatic Discharge Symposium, Dec 4, 2014

We examine strategies for optimizing investment in ESD protection and trade-offs that can arise. ... more We examine strategies for optimizing investment in ESD protection and trade-offs that can arise. Standard ESD measures require low expertise but may result in unnecessary equipment spend. Tailored EPAs may require higher expertise and greater training. ESD control measures and equipment used with inadequate understanding can fail to yield the potential benefits expected. Optimal ESD control results from understanding ESD threats and control, with effective implementation.