ESD-safe handling of MOS devices — identify the statement that is NOT a recommended precaution When working with MOS (especially CMOS) devices, which of the following is NOT a proper electrostatic discharge (ESD) handling precaution?

Introduction / Context:
MOS devices are highly sensitive to electrostatic discharge due to their thin gate oxides. Proper ESD handling protects components during shipping, storage, and bench work. Recognizing bad practices is as important as knowing good ones, since a single error can cause latent damage that is difficult to detect immediately.

Given Data / Assumptions:

• We focus on standard ESD precautions in labs and manufacturing.
• Goal: keep personnel, tools, and parts at the same potential.
• Prevent hot-plugging that might exceed absolute maximums.

Concept / Approach:
Good ESD control includes grounding equipment, using antistatic packaging, maintaining ESD-safe work areas, and having operators wear grounded wrist straps. Devices are often shipped with pin shorting or conductive foam to equalize potentials. The statement claiming that workers should not wear grounding straps is the opposite of best practice and is therefore the incorrect (NOT) precaution.

Step-by-Step Reasoning:

Verification / Alternative check:
Industry standards (e.g., ANSI/ESD S20.20) specify personnel grounding (wrist straps or heel-grounders) when handling sensitive devices.

Why Other Options Are Wrong:

• Grounding test equipment prevents potential differences.
• Shorting leads or using conductive foam during shipment equalizes pin potentials.
• Avoiding hot insertion prevents voltage spikes and latch-up.
• Antistatic bags and benches are standard ESD controls.

Common Pitfalls:

• Assuming ESD damage is always catastrophic; latent damage can degrade long-term reliability.

Final Answer:
Workers handling MOS devices should not have grounding straps attached to their wrists.