Optical modules, fiber optic network cards, and transceivers all contain sensitive semiconductor devices. Damage caused by electrostatic discharge often does not appear immediately until the link is online. This article sorts out the general specifications for ESD protection according to the process and is not targeted at a specific workshop.

Two discharge mechanisms and potential damage

Engineering focuses on two categories: the human body model, in which the accumulated charge is put into the device when the human hand touches the port, which mostly occurs in the plug-in and assembly process; and the device charged model, in which the module itself is charged and then discharged by the grounded conductor, which mostly occurs in automated assembly and turnover processes. The danger lies in potential damage. The device does not fail immediately but the withstand voltage margin has decreased. Problems will occur first when encountering high temperatures or surges. In the dry season, the humidity is low, and the human body potential is more likely to rise. Moisture vapor control and static electricity management are actually two sides of the same set of environmental controls.

Four bottom lines for warehousing and assembly

• Modules and boards are packaged in anti-static bags, and conductive or dissipative material containers are used for turnover. Ordinary plastic bags are not allowed to directly contact gold fingers;
• The assembly station is equipped with a wrist strap and a table pad and is connected to an independent earth path. Periodically check whether the wrist strap is still valid;
• The relative humidity of the environment is controlled at about 30% to 70%. When it is too low, electrostatic potential is easy to accumulate;
• Maintain continuous conductive contact from unpacking to putting on the machine, do not place modules bare on the table, and do not press tools on devices.

The two most easily overlooked actions at the operation and maintenance site

The first is to discharge before operation. Before touching the equipment, touch the metal part of the cabinet or release the charge through the wrist strap. This is especially necessary when wearing insulated shoes in winter. The second is to protect the ports. After the module is pulled out, wear a dust plug immediately and put it back into the anti-static bag. The optical and electrical ports are not left empty and exposed for a long time. When picking up a small-sized module, pinch the casing and do not touch the golden fingers or the inside of the optical port. Structural referenceSFP Gigabit single mode dual fiber 10KM optical module. During batch replacement in the data center, it is recommended to store old parts and spare parts in separate zones to avoid misinsertion and secondary discharge caused by mixed storage.

The determination of ESD management does not require special instruments. It only depends on whether the packaging is standardized, whether the wrist strap and table pad are grounded, and whether the humidity record exists. EB-LINK modules are packaged immediately after testing one by one. Users keep the original packaging until they are put on the machine, which is the lowest-cost way of self-protection.