Electrostatic discharge (ESD) safety: Which measure most directly reduces a technician’s ESD potential while working on sensitive electronics?
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ADe-ionizing fans
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BA wrist strap
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CRubber gloves with matching cap
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DA static meter
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ENone of the above
Answer
Correct Answer: A wrist strap
Explanation
Introduction / Context:Electrostatic discharge can damage semiconductor devices long before a human can feel a shock. Proper ESD control practices are vital when assembling, servicing, or transporting electronics.
Given Data / Assumptions:
- Work is performed at a bench with typical ESD controls available.
- The goal is to directly reduce a person’s electrostatic potential relative to ground and the device under service.
- Normal ESD-safe procedures (grounding points, mats) are in place or can be used.
Concept / Approach:
An antistatic wrist strap, when properly connected to a verified ground through a high-value resistor, equalizes potential between the technician and the equipment, preventing sudden discharges into components. While de-ionizing fans reduce ambient charge on surfaces and in air, the wrist strap directly controls the human body charge—the most common discharge source during handling.
Step-by-Step Solution:
Put on a wrist strap and connect it to an ESD ground point (through a 1 MΩ resistor).Work on an ESD mat connected to the same ground potential.Handle boards by edges; keep components in antistatic packaging until use.Verification / Alternative check:
Use an ESD tester to confirm strap continuity and proper resistance to ground. Observe reduced failure rates and avoid latent defects associated with ESD events.
Why Other Options Are Wrong:
- De-ionizing fans: Helpful, but they do not directly and reliably ground the technician.
- Rubber gloves with cap: Not an ESD control method and can increase triboelectric charging.
- A static meter: Diagnostic tool; does not reduce potential on its own.
- None of the above: Incorrect because a wrist strap is the standard control.
Common Pitfalls:
Failing to test the strap; clipping to floating or painted metal; removing the strap mid-task; ignoring ESD-safe packaging and footwear.
Final Answer:
A wrist strap