All MOS devices or Shop Replaceable units (SRUs) with MOS devices not in use should be stored in what type of package, so that all leads, pins are shorted via the package?

• A. Insulated Package
• B. Conductive Package
• C. Vacuum sealed
• D. Foam packaging

Answer: (B)

Electrostatic discharge (ESD) protection for MOS devices when they’re not in use is crucial because MOS inputs are highly sensitive to static charges. When a device is stored, any stray charge on its leads can create a voltage difference that damages the delicate oxide structure inside the MOS transistor. Using a conductive package provides a low-impedance path that ties all leads together, effectively shorting them through the package. This equalizes the potential across all pins and to ground, so static charges are dissipated rather than accumulating and striking the device.

Insulated packaging would not provide a discharge path, vacuum sealing doesn’t address voltage equalization, and foam packaging—while it may offer cushioning or anti-static properties—won’t reliably short all leads. The conductive package is designed specifically to prevent ESD by ensuring the leads are at the same potential.