Before inserting SRUs with MOS devices into test sockets or subassembly circuits , manually hold the SRU and the test equipment or subassembly chassis simultaneously to ensure what?

Before inserting SRUs with MOS devices into test sockets or subassembly circuits , manually hold the SRU and the test equipment or subassembly chassis simultaneously to ensure what?

• A. That all leads are long enough
• B. That devices are aligned
• C. That all items have common potential
• D. That power supply is off

Answer: (C)

The main idea is to prevent electrostatic discharge into a very charge-sensitive MOS device. MOS transistors have extremely thin oxide layers that can be damaged by even a small static charge. By holding the SRU and the test equipment or chassis at the same time, you create a common electrical potential between them and your body, allowing any static charge to flow away to ground instead of into the device. This equalizes potentials and dramatically reduces the risk of a damaging discharge when you insert the unit. Other points aren’t the primary safeguard here: ensuring leads are long enough won’t stop an ESD event, device alignment matters for fit but not for preventing static discharge, and turning the power off is good practice but doesn’t by itself establish a common potential to prevent ESD.

The main idea is to prevent electrostatic discharge into a very charge-sensitive MOS device. MOS transistors have extremely thin oxide layers that can be damaged by even a small static charge. By holding the SRU and the test equipment or chassis at the same time, you create a common electrical potential between them and your body, allowing any static charge to flow away to ground instead of into the device. This equalizes potentials and dramatically reduces the risk of a damaging discharge when you insert the unit.

Other points aren’t the primary safeguard here: ensuring leads are long enough won’t stop an ESD event, device alignment matters for fit but not for preventing static discharge, and turning the power off is good practice but doesn’t by itself establish a common potential to prevent ESD.