CIS CIS ESD Control & Protection 2 — Questions and Answers
Question 1: What is the Human Body Model (HBM) used for in ESD testing?
- Measuring the electrostatic voltage generated by an operator walking across a floor
- Simulating ESD events from a charged person touching a component (Correct answer)
- Modeling the ESD sensitivity of a PCB assembly
- Calculating safe handling voltages for production floor workers
Correct answer: Simulating ESD events from a charged person touching a component
The Human Body Model simulates an ESD event when a charged person (modeled as a 100 pF capacitor discharged through 1.5 kΩ) touches an electronic component.
Question 2: What color are most standard ESD protective bags and packaging materials?
- Red
- Yellow
- Pink or metallic shielding (silver/gray) (Correct answer)
- Blue
Correct answer: Pink or metallic shielding (silver/gray)
ESD-protective packaging is typically pink (for dissipative poly bags) or metallic silver/gray (for shielding bags that protect against electrostatic fields).
Question 3: What is the maximum acceptable voltage threshold for an ESD wrist strap continuous monitor alarm (upper limit)?
- 250V (Correct answer)
- 500V
- 1,000V
- 2,000V
Correct answer: 250V
Most ESD wrist strap continuous monitors alarm when the operator's body voltage exceeds 250V, signaling a grounding failure.
Question 4: Which ESD model most closely simulates the discharge from a metal tool or conductive object touching a component pin?
- Human Body Model (HBM)
- Machine Model (MM) (Correct answer)
- Charged Device Model (CDM)
- Transmission Line Pulse (TLP)
Correct answer: Machine Model (MM)
The Machine Model (MM) simulates discharge from metal objects like tools, fixtures, or automated handling equipment contacting a component.
Question 5: What does an ionizer (air ionizer) do in an ESD control program?
- Removes humidity from the air to prevent condensation on components
- Neutralizes static charges on insulative surfaces and isolated conductors that cannot be grounded (Correct answer)
- Tests the ESD sensitivity of components before handling
- Generates a clean static-free compressed air supply for cleaning
Correct answer: Neutralizes static charges on insulative surfaces and isolated conductors that cannot be grounded
An ionizer produces positive and negative ions that neutralize static charges on surfaces that cannot be directly grounded, such as plastic parts or component bodies.
Question 6: According to ANSI/ESD S20.20, floor materials in an ESD Protected Area must have a resistance-to-ground of no more than:
- 1 × 10⁷ ohms
- 1 × 10⁹ ohms (Correct answer)
- 1 × 10¹¹ ohms
- 1 × 10¹² ohms
Correct answer: 1 × 10⁹ ohms
ANSI/ESD S20.20 requires ESD flooring to have a resistance-to-ground of no more than 1 × 10⁹ ohms (1 gigaohm) to ensure static charge dissipation.
CIS CIS ESD Control & Protection 2
What is the Human Body Model (HBM) used for in ESD testing?