ESD ESD BASICS BASICS Basic Concepts in ElectroStatic Discharge (ESD) Copyright 2017 Desco Europe April 2017 Introduction ESD Control Training Per EN 61340-5-1 clause 5.2.2 Training plan: initial and
recurrent ESD awareness and prevention training shall be provided to all personnel Use PowerPoint with Desco Europe ESD Awareness Guide (available online) DescoEurope.com Safety Safety First - Concern WHEN Working Around High Voltage As important as ESD control is, it is of secondary importance compared to employee safety When working with voltages over 250 VAC, ESD personnel grounding should not be used including Wrist Straps, ESD Footwear & Garments
Ground fault circuit interrupters (GFCI) and other safety protection should be considered wherever personnel might come into contact with electrical sources. DescoEurope.com Introduction The written ESD Control Plan should be in accordance with EN 61340-5-1 clause 5.2.1: The organization shall prepare an ESD control program plan that addresses each of the requirements of the program. Those requirements concern training, compliance verification, grounding/ bonding systems, personnel grounding, EPA [ESD protected area] requirements, packaging systems, marking. ESD training should be repeated as specified in the
companys written ESD Control Plan Quizzes in Awareness Guide could be objective evaluation technique to ensure trainee comprehension and training adequacy. DescoEurope.com Static Electricity OR Electrostatic Charge Defined as Electric charge at rest All Materials Tribocharge ElectroStatic Charge Generation or Tribocharging When 2 surfaces contact then separate. Some Electrons move or are given up
to the other surface, causing an imbalance. Electrons are Negative. Protons are Positive. DescoEurope.com All Materials Tribocharge ElectroStatic Charge Generation: Opening plastic bag, combing hair, unrolling tape, etc. Build up charge walking on carpet, sliding across car seat. Charge greater when weather is cold and dry.
ESD, discharge, is when the charge moves. DescoEurope.com Charge Generation or Tribocharging When two materials make contact and are then separated, a transfer of electrons from one material to the other may take place. The amount of static electricity generated depends upon the materials subjected to contact or separation, friction, the area of contact or separation, and the relative humidity of the environment. At lower relative humidity, as the environment is drier,
charge generation will increase significantly. Common plastics generally will create the greatest static charges. DescoEurope.com ESD ESD or or ElectroStatic ElectroStatic Discharge Discharge Charges Seek Balance Discharge is Rapid Creating Heat If two items are at
different electrostatic charge levels, as they approach one another, a spark or Electrostatic Discharge (ESD) can occur. This rapid, spontaneous transfer of electrostatic charge can generate heat and melt circuitry in electronic components. DescoEurope.com Examples Of Electrostatic Discharge or ESD
Lightning Zap from a door There are innumerable ESD events occurring which you do not see or feel. ESD is the hidden enemy in a high tech manufacturing environment. DescoEurope.com Photo of ESD arcing from finger to component This is not a computer simulation. Technician was connected to a small magneto. Photos courtesy of Hi-Rel Laboratories,
Inc., Spokane, WA DescoEurope.com Scanning electron micrograph (SEM) image of the ESD damage after removal of the capacitor metallization. Note the characteristic eruption thru the oxide. Magnification is 10,500 times. Photos courtesy of of Hi-Rel Laboratories, Inc., Spokane, WA DescoEurope.com
Two Two Types Types of of Materials Materials Conductors Conductors Electrical Current Flows Easily So Can be Grounded Examples: metals, carbon and people (due to impurities the human body's sweat layer) Materials that are called dissipative are conductors, able to remove electrostatic charges to ground. The resistance of dissipative
materials is the higher portion of the conductive range. DescoEurope.com Two Two Types Types of of Materials Materials Insulators Insulators Insulators or Non-Conductors Electrical Current Does Not Flow Easily So Cannot be Grounded
Example: Plastics, glass, and dry air Insulators like this plastic cup will hold the charge and cannot be grounded and "conduct" the charge away. DescoEurope.com Typical Typical ElectroStatic ElectroStatic Voltages Voltages Walking across a carpet:
1,500 - 35,000 volts Walking over untreated vinyl floor: 250 - 12,000 volts Vinyl envelope used for work instructions: 600 - 7,000 volts Worker at a bench: 700 - 6,000 volts Unwinding regular tape: 9,000 - 15,000 volts Higher number is generated at low humidity DescoEurope.com Costly
Costly Effects Effects Of Of ESD ESD People Discharge Frequently But to Feel a Discharge it must be about 2,000 volts DescoEurope.com ESD ESD That That aa Person Person Cant
Cant Feel Feel Can Can Easily Easily Damage Damage Electronic Electronic Components Components Even less than100 volts might damage a component! DescoEurope.com ESD is The Hidden Enemy
Consider all electronic components ESD sensitive Program may identify classification of sensitivity to ESD damage Newer electronic components can have reduced width of circuits and microscopic spacing of insulators within them, increasing their sensitivity to ESD ESD damage cannot be seen by the naked eye DescoEurope.com Optical photo of a large Integrated Circuit which has experienced ESD damage to the pin noted by the arrow.
Photos courtesy of of Hi-Rel Laboratories, Inc., Spokane, WA DescoEurope.com Higher magnification photo of pin noted by the arrow in the prior slide This taken at 400 times magnification on a 4" X 5" photo. The damage is noted as the "fuzz" at the end of the arrow. Photos courtesy of of Hi-Rel Laboratories, Inc., Spokane, WA DescoEurope.com
Now you see it!! Overlying glassivation has been removed and the surface decorated to show the ESD damage at 5,000 times magnification in this scanning electron micrograph. Photos courtesy of of Hi-Rel Laboratories, Inc., Spokane, WA DescoEurope.com Types Types Of Of ESD ESD
Device Device Damage Damage Catastrophic Failures Inspection is able to detect failure Latent Defect Component wounded but Inspection passes as good
DescoEurope.com Latent Defects More Costly Sub Assembly passes inspection Assembly passes inspection Product passes inspection Works a while for customer Then Upsets & Mysterious Problems More Returns More Warranty Costs Lower Customer Satisfaction DescoEurope.com
Repair Costs Increase if Failure Detected Later One study indicated the repair cost to be: $10 Device $10 Device in board - $100 $10 Device in board and in system - $1,000 $10 Device and system fails - $10,000 Catastrophic failures are detected during inspection but components with latent defects pass as good DescoEurope.com Latent Defects
Most Frustrating Pass inspection as good May fail later Cause equipment down time Costly field repair work Adversely impacting customer satisfaction Hidden Enemy ESD damage may occur Cannot be felt Cannot be seen Not detected through normal inspection procedures DescoEurope.com
Like Germs, ESD Is The Hidden Enemy erilisation in medicine Control ESD Control Germs You would never consider having surgery in a contaminated operating room, you should never handle electronic assemblies without taking adequate protective measures against ESD DescoEurope.com
The Prerequisites of ESD Control Identify ESD Protected Area Identify ESD sensitive items Provide ESD control training DescoEurope.com The Basics Of ESD Control Ground Conductors Remove or Neutralise Insulators with Ionisers
Shield ESDS [ESD sensitive items] when Stored or Transported outside EPA DescoEurope.com Ground Conductors Including People Personnel Grounding Devices Wrist Straps Snug on skin
Clean Cord connected to ground Foot Grounders Grounding tab under foot Worn on both feet Contact to ESD floor DescoEurope.com Daily Test Personnel Grounding Devices Wrist Straps Must work, so
test wrist strap daily monitors) (or use continuous Foot Grounders Must work, so test foot grounder daily DescoEurope.com Workstation Grounding Devices Dissipative Worksurfaces Ground ESD working surface via ground
point to protective earth ground ground cord to common Conductive Floor Mats Ground ESD floor mats via ground point to protective earth ground ground cord to common DescoEurope.com Clean Using Only ESD Cleaners
Dissipative Working Surfaces You should be aware of the type of working surfaces and flooring materials used by your company Be sure to keep your working surface clean, and follow the maintenance procedures recommended by the manufacturer Regular cleaners contain silicone, an insulator DescoEurope.com Neutralise Insulators Via Ionisation
Insulators cannot be grounded Ioniser air flow floods area with Ions - Neutralising Charge DescoEurope.com Direct Ioniser Air Flow to ESD Sensitive Items Ionisers produce positively and negatively charged ions Fans airflow to cover the work area Ionisation can reduce static charges on an insulator or isolated conductors DescoEurope.com Types of Ionisers
Bench Top Ionisers Neutralising Air Nozzles / Hand Gun Overhead Ionisers Neutralise charges on insulators and isolated conductors Ionisers require periodic cleaning of emitter pins If out of balance (offset voltage) they can charge items DescoEurope.com Shield ESD Sensitive Items Outside Protected Area Faraday Cage effect charges to be conducted on surface of the conductor.
Since like charges repel, charges will rest on the exterior. Charges Kept on Outside of Package: Closed Metallised Shielding Bag Covered Conductive Tote Box DescoEurope.com ESD Packaging Electrostatic discharge shield "A barrier or enclosure that limits the passage of current and attenuates an electromagnetic field resulting from an electrostatic discharge." ESD bags should be closed and containers have lids in place ESD packaging only be opened at an ESD protective
workstation by properly grounded personnel. DescoEurope.com ESD Protected Workstations An ESD protective workstation is an area that has been established to effectively control electrostatic charges and discharges. Grounding all conductors (including people) Removing all insulators Or neutralising process essential insulators with an ioniser
DescoEurope.com ESD Protected Products Best Practice Remove Insulator or Change to ESD Protective Version
ESD Garments and Gloves Conductive Foam & Shunt Bars Dissipative Binders & Document Protectors Conductive & Dissipative Flooring ESD Packaging, bags, boxes, etc. ESD Tape ESD Carpeting, Tiles, etc. Dissipative Floor Finishes ESD Bags and Material Handling Containers DescoEurope.com You Are On The Front Lines Fighting The Hidden Enemy
Only allow trained or people in EPA Ground all conductors including people at ESD workstation escorted Test wrist straps at least daily, or use continuous
monitors Test ESD footwear at least daily, if used DescoEurope.com You Are On The Front Lines Fighting The Hidden Enemy Visually check all grounding to make sure they are Handle unpacked ESDS items when grounded Keep wrist band snug, foot grounder grounding tab in shoe,
ESD smocks buttoned up cords connected only and DescoEurope.com You Are On The Front Lines Fighting The Hidden Enemy Make sure Ionisers are maintained and airflow directed at ESDS
items Use discharge shielded packaging for shipping or storing ESDS outside the EPA DescoEurope.com
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