Electrostatic Sensitive Devices Quiz

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Questions and Answers

What is the primary purpose of tote boxes in an ESD-controlled environment?

Protection from dust and debris

Organization of tools and equipment

Transportation of devices and PCBs (correct)

Storage of bulk materials

What type of material is commonly used for the fabrication of DIP tubes?

Only aluminium

Carbon-loaded plastic and anti-static plastic (correct)

Only plain plastic

Only anti-static plastic

Which of the following is NOT a characteristic of an effective ESD tote box?

Prevention of triboelectric charge generation

Porous design for ventilation (correct)

Conductive material

Shielding from external static fields

Why are DIP tubes considered closed containers for the purposes of static shielding?

The end openings are relatively small. (A) Signup and view all the answers

What is the key advantage of using a tote box with a lid over a conductive tray alone?

Tote boxes provide greater protection from external static fields. (C) Signup and view all the answers

What has led to circuits now switching hundreds of thousands of times a second?

Improvements in semiconductor responsiveness (B) Signup and view all the answers

What type of failure occurs when a component is so damaged that it will never function again?

Catastrophic failure (C) Signup and view all the answers

How can latent failures caused by ESD be described?

Leading to degraded performance over time (B) Signup and view all the answers

What can be a consequence of latent failures in components fitted to aircraft?

They cause significant repair costs and downtime (D) Signup and view all the answers

What is the nature of upset failures resulting from ESD?

They result in intermittent gate leakage (A) Signup and view all the answers

What is a possible effect of static charge on semiconductor components?

Complete breakdown of component functionality (C) Signup and view all the answers

Why may a component pass inspection but later fail in operation?

It has only marginal damage from ESD (C) Signup and view all the answers

What is an upset failure in the context of ESD damage?

A minor current flow causing intermittent software glitches. (B) Signup and view all the answers

Why are upset or latent failures particularly challenging to identify?

They may pass normal testing procedures even when present. (B) Signup and view all the answers

What does ESD stand for?

Electrostatic Discharge. (B) Signup and view all the answers

How can ESD damage to a component be visually represented?

As a pinhole that may indicate significant internal damage. (A) Signup and view all the answers

What economic rationale supports the implementation of ESD safeguards?

The expenses caused by ESD damage exceed the investment in protective measures. (A) Signup and view all the answers

What often characterizes direct catastrophic failures due to ESD?

They are immediately visible and detectable. (B) Signup and view all the answers

What can be a consequence of ESD damage in avionics systems?

Intermittent faults that are difficult to replicate. (D) Signup and view all the answers

What does the magnification difference (175x vs 4300x) suggest about ESD damage in components?

Some damage may not be apparent without high magnification. (A) Signup and view all the answers

What could prevent ESD damage in electronic components?

Proper ESD control measures and workstations. (C) Signup and view all the answers

What is the safest precaution to avoid damaging electronic devices from ESD?

Discharge static electricity by touching an earthed conductive surface. (D) Signup and view all the answers

Which action should be avoided to prevent ESD damage?

Touching the edge connectors of circuit cards. (B) Signup and view all the answers

Before disconnecting cables from electronic equipment, you should first:

Ensure the aircraft is grounded and powered off. (C) Signup and view all the answers

When should electronic devices be inserted into a circuit or connector?

Immediately after removing from the packaging. (B) Signup and view all the answers

What is the primary purpose of pink poly anti-static bags?

To package Class III sensitivity level components (A) Signup and view all the answers

What should be done with electronic equipment when maintenance is performed?

Put it in a grounded anti-static mat. (A) Signup and view all the answers

Why should you not touch the sockets or pins within the plugs of electronic equipment?

To minimize the risk of ESD damage. (C) Signup and view all the answers

What characteristic of anti-static packaging material primarily influences its effectiveness?

Electrical resistance around the container (C) Signup and view all the answers

What should be used for shipping electronic components?

Approved anti-static containers and bags. (C) Signup and view all the answers

How does the shelf life of pink poly anti-static bags compare to cushion-pack bags?

Pink poly anti-static bags last longer (B) Signup and view all the answers

Which type of anti-static bag is recommended for components with Class 1 sensitivity levels?

Metallic anti-static bags (A) Signup and view all the answers

Which of the following is a correct method to equalize electrostatic potentials?

Touch the outer shell of the plug to the equipment mating connector. (D) Signup and view all the answers

What is a primary reason for not opening ESD-sensitive equipment except at an ESD workstation?

To minimize the risk of ESD damage. (C) Signup and view all the answers

What is a key feature of the interior layer of metallic anti-static bags?

It prevents the generation of static inside the bag (B) Signup and view all the answers

Which of the following ESD precautions is overly cautious or unnecessary?

Avoiding storage near strong electromagnetic fields. (A) Signup and view all the answers

What material is used in the construction of cushion-pack bags?

Laminated polyethylene with cushioning (D) Signup and view all the answers

What is the effect of wrinkling or creasing on pink poly anti-static bags?

It has no negative effect (B) Signup and view all the answers

Which of the following characteristics is NOT true about metallic anti-static bags?

They are unsuitable for rugged handling (D) Signup and view all the answers

What feature of pink poly anti-static bags allows for convenience when accessing items frequently?

They are available with an anti-static zipper (A) Signup and view all the answers

What type of static protection is not provided by anti-static plastics?

Electrostatic shielding (A) Signup and view all the answers

Study Notes

Electrostatic Sensitive Devices (5.12)

Learning objectives include special handling of components sensitive to electrostatic discharges (Level 2)
Understanding the risks and possible damage caused by electrostatic discharges (Level 2)
Knowing about component and personnel anti-static protection devices (Level 2)

Static Electricity

Static electricity is an electrical charge at rest, unlike current electricity
It can be generated by friction or induction
Triboelectric charge is the build-up of static electricity through friction
Walking across a carpet can generate a static charge of up to 35,000 volts on the human body
The body can feel a shock from a discharge of 3000 volts
Damage to electrostatic-sensitive circuits can occur from a discharge of only a few hundred volts
Arcing indicates the discharge or equalisation of a potential difference.

Induced Static Charges

Simple induction occurs when a conductor is in the presence of an electrostatic field
Positive and negative charges separate on the conductor
The electrons are attracted to the positive charge
The same effect happens with strong magnetic fields
Upon removal, electrons rush back to neutralise the imbalance, creating a current that could damage the circuit
Sensitive integrated circuits (ICs) can be damaged by external magnetic or electrostatic fields, even without direct contact with an ESD source.

Compound Induction

If a conductor is grounded, it can attract more electrons, further increasing the electrical potential
Removing the ground creates a net negative charge
When the field is removed, the charges equalise, resulting in a negative potential across the conductor's surface
This is compound induction

Dangerous Situations Generating Static Charge

Low relative humidity (10-20%)
Walking on carpets
Walking on vinyl floors
Working at a workbench
Using vinyl envelopes
Handling polythene bags
Sitting in a chair with urethane foam

Metal-Oxide-Semiconductor Devices

MOSFETs are very susceptible to ESD damage
Parts susceptible to ESD damage are those in any logic family, requiring small energy changes or voltage changes.
Examples are NMOS, PMOS, CMOS, and TTL items.
ESD damage can damage components through arcing through the insulating silicon dioxide layer
External magnetic or electromagnetic fields can also damage components

ESD Sensitivity

Human Body Model (HBM) is a test method measuring ESD sensitivity
A charged 100-pF capacitor is discharged into the device via a 1500-Ω resistor.
The withstand voltage is the maximum test voltage without causing damage.
Component sensitivity levels such as VMOS, MOSFET, EPROM, JFET, OP-AMP, Schottky Diodes, Film Resistors, and Schottky TTL have varying withstand voltages

Device Sensitivity Classification

Components with a maximum ESD withstand voltage of 16,000V or less are considered ESD sensitive.
Classification includes:
- Class 1 (Extremely sensitive) 0–2 kV
- Class 2 (Sensitive) 2–4 kV
- Class 3 (Less sensitive) 4–16 kV

Circuit Cards

ESD-sensitive components on circuit cards are still susceptible to ESD.
Special care is needed to prevent ESD from entering through connector receptacles.

Types of ESD Damage

Catastrophic failures : Components are irreparably damaged (e.g., junction breakdown, metal melt)
Latent failures: Components are weakened or degraded, leading to poor performance over time
Upset failures: Intermittent faults or software glitches may occur, which are hard to diagnose

ESD Handling Precautions

Do not touch the pins of components
Do not touch the sockets, plugs, or pins of equipment
Discharge static electricity by touching a grounded surface
Ground the equipment during removal
Equalise electrostatic potentials before disconnecting cables, and immediately cover disconnected plugs.
Use designated ESD work areas
Use conductive wrist straps while working
Use static dissipative materials and equipment
Use conductive packaging, like bags and trays

ESD Safe Workplace

Requires a grounded ESD-protective work surface
Use ESD-safe flooring
Provide personnel grounding (like wrist straps)

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Description

Test your knowledge about electrostatic sensitive devices and the precautions necessary for handling them. This quiz covers the risks associated with electrostatic discharges, the sources of static electricity, and anti-static protective measures. Assess your understanding of how static electricity can affect electronic components.