Discharge, electrostatic

The main tests for assessment of electrostatic discharge are (USA) the following. ASTM D 257-75 (reapproved 1983) - standard test methods for DC resistance or conductance of insulating materials. Federal Test Method Standard No lOlC - 13 March 1980, Method 4046.1 - 8 October 1982 (charge notice 1). This measures the charge decay time of materials in film and sheet form. The maximum time accepted for charge dissipation is two seconds (as stated in MIL-B81705B-2,February 1972). 

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A. F. Schlack, "Susceptibihty of Electric Primers and Electrostatic Discharges" ia Minutes of the 15th Explosives Safety Seminar, AD-775 580, NTIS, Spriugfield, Va., 1973. 

Static electric discharge is a serious problem ia the electronics iadustry. Electronic devices are extremely seasitive to static electric discharges. Examples of the seasitivity to electrostatic discharge (ESD) are givea ia Table 2 (26). 

N. Sclater, Electrostatic discharge Trotection for Electronics Tab Books, Blue Ridge, Pa., 1990. 

R. Walker, Electrical Overstress j Electrostatic Discharge Symposium, EOS /FSD Association, Rome, N. Y., 1983. 

TABLE 26-21 Examples of Different Types of Electrostatic Discharges... 

Electrostatic Discharges An electrostatic discharge takes place when a gas or vapor-air mixture is stressed, electrically, to its breakdown value. Depending upon the specific circumstances, the breakdown appears as one of four types of discharges, which vary greatly in origin, appearance, duration, and incendivity. 

Deterioration of pipe/hose lining due to chemical attack or electrostatic discharge. 

Stray Electrical Currents and Induced Radio Frequency Currents. For information on stray currents see API 2003 [3j. For information on both hazards see the author s review Sources of Ignition in [157]. Electrostatic Discharge (ESD) Damage to Electronic Equipment. Marine Tankers and Barges (see [5] ISGOTT ). 

During the test, hydrogen flow rate was raised to a maximum of approximately 55 kg/s (120 Ib/s). About 23 seconds into the experiment, a reduction in flow rate began. Three seconds later, the hydrogen exploded. Electrostatic discharges and mechanical sparks were proposed as probable ignition sources. The explosion was preceded by a fire observed at the nozzle shortly after flow rate reduction began. The fire developed into a fireball of modest luminosity, and an explosion followed immediately. 

To avoid electrostatic discharging or even charging, the following list of conditions suggested by Haase [63] should be considered ... 

Graphite Low cost (5-15 cents per square foot) easy application excellent ESD (electrostatic discharge) performance. Less conductivity (ranging from 2 ohms to the thousands per square foot, depending upon the amount of graphite) modest shielding capability (up to 30-40 dB). 

Initiation by Electrostatic Discharge. Jackson (quoted in Vol 5, E45) found the max nonignition voltage and non-ignition energy for... 

Effect of Heat, (see Thermal Decomposition) Electrostatic Sensitivity. An electrostatic discharge of over 5 joules is required to initiate AP (NG 3 joules) (Ref 24, p 46). ... 

Sensitivity to Electrostatic Discharge. Thru 100 mesh material, confined 6.0 joules, unconfmed 0.025 joules (Ref 10)... 

Luo et al. [1,153] used a slurry containing ultra-fine diamond (UFD) powders to polish the surface of HDD sliders. The powders are from 3 nm to 18 nm in diameter and 90 % around 5 nm. They are crystal and sphere-like [154]. The pH value of the slurry is kept in the range from 6.0 to 7.5 in order to avoid the corrosion of read-write heads, especially pole areas. A surface-active agent is added into the slurry to decrease the surface tension of the slurry to 22.5 Dyn/cm, and make it spread on the polish plate equably. An anti-electrostatic solvent is also added to the slurry to avoid the magnetoresistance (MR) head being destroyed by electrostatic discharge. The anion concentration of the slurry is strictly controlled in ppb level so as to avoid the erosion of magnetic heads as shown in Table 5. The concentration of UFDs in the slurry is 0.4 wt %. 

After lapping, the sliders will be cleaned, and then a passivation film of diamond-like carbon (DLC) will be deposited on the surfaces of sliders through chemical vapor deposition (CVD) to protect the pole area from chemical-physical corrosion and electrostatic discharge attack. Corrosion in pole areas will result in loss of read/write functions. A corrosion test was taken to examine the ability of the sliders polished by different slurries as shown in Table 6. It can be seen that the MRR change rate of the sliders polished by UFD slurry is much less than that polished by the slurry T5qre III, that is, the capability of anti-corrosion of the former is much better than that of the latter. 

Lead styphnate is a poor initiating explosive which when dry is very sensitive to friction and impact, to electrostatic discharge, and to flame. Its main use is as an additive to lead azide to improve flame sensitiveness (see p. 101). When pressed to a density of 2-6 g ml-1 it has a velocity of detonation of4900 m s l. 

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