Electrostatic Discharge Test
This test relates to equipment, systems, sub-systems and peripherals which
may be involved in static electricity discharges owing to environmental and installations
conditions, such as low relative humidity, use of low-conductivity (artificial-fiber)
carpets, vinyl garments, etc., which may exist in allocations classified in standards
relevant to electrical and electronic equipment.
The problem of protecting equipment against the discharge of static electricity has
gained considerable importance for manufacturers and users.
The extensive use of microelectronic components has emphasized the need to define the
aspects of the problem and to seek a solution in order to enhance products/system
reliability.
The problem of static electricity accumulation and subsequent discharges becomes more
relevant for uncontrolled environments and the widespread application of equipment and
systems in a wide range of industrial plants.
Equipment may also be subjected to electromagnetic energies whenever discharges occur
from personnel to nearby objects. Additionally, discharges can occur between metal
objects, such as chairs and tables, in the proximity of equipment. However, based on
limited experience available to date, it is considered that the tests here may adequately
simulate the effects of the latter phenomenon.
The effects of the operator discharge may be a simple malfunction of the equipment or
damage of electronic components. The dominant effects can be attributed to the parameters
of the discharge current (rise time, duration, etc.).
Electrostatic discharges are applied to the EUT at points and surfaces which are
normally accessible to the operator. These discharges are also applied to the metal
coupling planes. The voltage levels are increased gradually until the maximum severity
level selected is reached. Discharges to the EUT and coupling plane are performed at a
minimum of 1 second intervals at each polarity. The minimum of 10 discharges at each
polarity are initially performed and increased to 30 discharges as the voltages increase
in severity so as to evaluate the performance of the EUT.
The preferential range of test levels for the ESD test is given below.
Testing shall also be satisfied at the lower levels given in the table.
Contact discharge is the preferred test method. Air discharges shall be used where
contact discharge cannot be applied. Voltages for each test method are given in the table
below. The voltages shown are different for each method due to the differing methods of
test. It is not intended to imply that the test severity is equivalent between test
methods.
