measurements.
6. The potential at any point should not exceed 0.75 volts RMS. A
leakage current tester (Simpson Model 229 or equivalent) may be used
to make the hot checks, leakage current mu3st not exceed 1/2
milliamp. In case a measurement is outsideof the limits specified,
there is a possibility of a shock hazard, and the equipment should be
repaired and rechecked before it is returned to the customer.
3. PREVENTION OF ELECTRO STATIC DISCHARGE
(ESD) TO ELECTROSTATICALLY SENSITIVE (ES)
DEVICES
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such
components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES
devices are integrated circuits and some field-effect transistorsand semiconductor "chip"
components. The following techniques should be used to help reduce the incidence of component
damage caused by electro static discharge (ESD).
1. Immediately before handling any semiconductor component or
semiconductor-equipped assembly, drain off any ESD on your body by
touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging ESD wrist strap, whichshould be
removed for potential shock reasons prior to applying power to the
unit under test.
2. After removing an electrical assembly equipped with ES devices, place
the assembly on a conductive surface such as alminum foil, to prevent
electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES
devices.
4. Use only an anti-static solder removal device. Some solder removal
devices not classified as "anti-static (ESD protected)" can generate
electrical charge sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate electrical
charges sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective package
until immediately before you are ready to install it. (Most replacement
ES devices are packaged with leads electrically shorted together by
conductive foam, alminum foil or comparableconductive material).
7. Immediately before removing the protective material from the leads of
6 |
ACEC
