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5.12 Electrostatic sensitive devices
1. Module 5: Digital Techniques and
Electronic Instrument Systems
5.12 Electrostatic Sensitive Devices
2. Electrostatic discharge
ESD: Electrostatic Discharge.
The sudden flow of electricity
between two objects.
Caused by imbalance of
electrons between the 2 objects.
A field created by tens of volts
between the 2 objects is enough
to damage a RAM module.
Walking on a vinyl floor can
generate up to 12,000V of static
electricity.
ESD abbreviation can also mean
“Electrostatic Sensitive Device”
3. Common Electrostatic Sensitive Devices &
actions causing ESD.
Devices prone to ESD:
MOSFETS
CMOS ICs (Chips)
Computer cards (CPU, GPU, etc.)
LED, Diodes
Actions causing ESD:
Opening a plastic bag.
Removing a tape from a roll or a container.
Transporting computer components around with trays or
carts.
Dry environments (non-humid) increase the possibility of
ESD.
4. ESD Prevention of working personnel
Methods to remove
charge from the human
body:
Touching metallic objects.
Wrist band.
Antistatic garment.
5. Other methods to prevent ESD when
working with electronic equipment
Avoid touching connections or
pins.
Ground all test equipment.
Use Antistatic mat:
Made a low resistance
material (10ΚΩ to 100ΜΩ) that
is grounded. It allows slow
discharging.
Use Antistatic Agent:
A compound used that makes
the surface of a material
conductive, thus reducing or
preventing ESD. Usually
absorbs moisture from the air.
They are often added to jet
fuels.
6. ESD Preventing Materials
Conductive Materials:
Materials with resistance between 1ΚΩ & 1ΜΩ/m2
Dissipative Materials:
Materials with resistance between 1ΜΩ /m2 & 1ΤΩ /m2
Shielding Materials:
Materials that attenuate current and electric fields.
7. Static electricity on the aircraft
The aircraft picks static charges from rain, cloud,
snow etc. (precipitation static)
• Strong charges developed between different parts of the plane
can break down the insulator between them.
• Problems caused by static electricity on the aircraft:
Material damage, Corrosion, Electromagnetic interference etc.
8. Corona Threshold and
Static electricity control
The Corona Threshold: High velocity gasses exiting
the engine Static electricity dissipates
surrounding atmosphere from sharp edges EMF.
Solutions to control static electricity:
Bonded (i.e. interconnection) of electronic equipment.
Wickes (to eliminate static electricity dissipation from
sharp edges).
