5.12 ELECTROSTATICS SENSITIVE DEVICE

www.part66.blogspot.com

ESD

• Electrostatic Sensitive Devices (ESD) are electronic components and other parts that are prone to damage from stray electric charge.

• Extensive (and permanent) damage to static sensitive devices can result from mishandling and inappropriate methods of storage and transportation.

STATIC ELECTRICITY

• When two dissimilar, initially uncharged non-conducting materials are rubbed together, the friction is responsible in transferring charge from one material to.

• The process of electron transfer known as 'triboelectric charging'.

• The amount of charge depends on factors like the rate of separation, humidity etc.

POSITIVE TRIBOELECTRICThe following materials give up electrons and become positive when charged when rubbed

against other materials:

• Air (most positive) • Dry human skin• Leather • Rabbit fur • Glass•Human hair• Nylon • Wool•Lead •Cat fur• Silk • Aluminium• Paper (least positive).

NEGATIVE TRIBOELECTRICThe following materials tend to attract electrons when rubbed against other materials and

become negative when charged:

• Wood (least negative) • Amber• Hard rubber • Nickel, copper, brass & silver• Gold and platinum • Polyester• Polystyrene • Saran• Polyurethane • Polyethylene• Polypropylene • Polyvinylchloride (PVC)• Silicon • Teflon (most negative)

VALUE ELECTROSTATIC

CAUSES ESD

• Electrostatic discharge from a human body • charged material to the ESDS device.• Electrostatic discharge from the device• Field induced discharges

ESD WARNING

HANDLING ESD EQUIPMENT

• Placards installed on the ESD LRU• The ESD printed circuit boards are identified with a static

sensitive placard.• Contaminated or unwanted material should be kept clear

of the sensitive devices. • Connect the wrist strap into the Electrostatic Ground Jack

of the card file or recognised aircraft ESD ground point.• LRU or circuit boards are to be placed in the correct

conductive bag or container which must display an ESD label.

TRANSPORTING ESD EQUIPMENT

1. Use of wrist straps which must be worn when handling ESD2. Use a heel strap3. Use of static dissipative floor and bench mats.4. Avoidance of very dry environments5. Availability of ground jacks6. Use of grounded test equipment7. Use of low-voltage soldering equipment and anti-static soldering

stations 8. Use of anti-static insertion and removal tools for integrated

circuits.9. Avoidance of nearby high-voltage sources10.Use of anti-static packaging

WRIST STRIP