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).
- 9. Wicks
- 10. ESD signs