Teledyne MODEL T703 Manual Do Utilizador
A Primer on lectro-Static Discharge
Teledyne API T703 Calibrator Operation Manual
218
12.2. HOW ELECTRO-STATIC CHARGES CAUSE DAMAGE
Damage to components occurs when these static charges come into contact with an electronic device. Current
flows as the charge moves along the conductive circuitry of the device and the typically very high voltage levels
of the charge overheat the delicate traces of the integrated circuits, melting them or even vaporizing parts of
them. When examined by microscope the damage caused by electro-static discharge looks a lot like tiny bomb
craters littered across the landscape of the component’s circuitry.
flows as the charge moves along the conductive circuitry of the device and the typically very high voltage levels
of the charge overheat the delicate traces of the integrated circuits, melting them or even vaporizing parts of
them. When examined by microscope the damage caused by electro-static discharge looks a lot like tiny bomb
craters littered across the landscape of the component’s circuitry.
A quick comparison of the values in Table 12-1 with the those shown in the Table 12-2, listing device
susceptibility levels, shows why Semiconductor Reliability News estimates that approximately 60% of device
failures are the result of damage due to electro-static discharge.
susceptibility levels, shows why Semiconductor Reliability News estimates that approximately 60% of device
failures are the result of damage due to electro-static discharge.
Table 12-2: Sensitivity of Electronic Devices to Damage by ESD
DAMAGE SUSCEPTIBILITY VOLTAGE
RANGE
DEVICE
DAMAGE BEGINS
OCCURRING AT
CATASTROPHIC
DAMAGE AT
MOSFET 10
100
VMOS 30
1800
NMOS 60
100
GaAsFET 60
2000
EPROM 100
100
JFET 140
7000
SAW 150
500
Op-AMP 190
2500
CMOS 200
3000
Schottky Diodes
300
2500
Film Resistors
300
3000
This Film Resistors
300
7000
ECL 500
500
SCR 500
1000
Schottky TTL
500
2500
Potentially damaging electro-static discharges can occur:
Any time a charged surface (including the human body) discharges to a device. Even simple contact of a
finger to the leads of a sensitive device or assembly can allow enough discharge to cause damage. A
similar discharge can occur from a charged conductive object, such as a metallic tool or fixture.
similar discharge can occur from a charged conductive object, such as a metallic tool or fixture.
When static charges accumulated on a sensitive device discharges from the device to another surface
such as packaging materials, work surfaces, machine surfaces or other device. In some cases, charged
device discharges can be the most destructive.
device discharges can be the most destructive.
A typical example of this is the simple act of installing an electronic assembly into the connector or wiring
harness of the equipment in which it is to function. If the assembly is carrying a static charge, as it is
connected to ground a discharge will occur.
connected to ground a discharge will occur.
Whenever a sensitive device is moved into the field of an existing electro-static field, a charge may be
induced on the device in effect discharging the field onto the device. If the device is then momentarily
grounded while within the electrostatic field or removed from the region of the electrostatic field and
grounded somewhere else, a second discharge will occur as the charge is transferred from the device to
ground.
grounded while within the electrostatic field or removed from the region of the electrostatic field and
grounded somewhere else, a second discharge will occur as the charge is transferred from the device to
ground.
07223B DCN6378