Handling tips

ESD handling

ESD introduction

Any object has a parasitic capacitance (C). The electrostatic charge occurs when two different materials rub or slide together or become detached. Examples are: walking over synthetic floors, rubbing of synthetic garments, shifting of plastic boxes. Due to this charge (Q) and the capacitance, an electrostatic potential (V) appears between any two objects:

V=Q/C

An electrostatic discharge (ESD) is the loss of charge (Q) that can occur when a sufficiently high quantity of charge is accumulated on an object. For an ESD event to occur, charge must be generated, accumulated, and discharged.

A net charge generates an electric field. This electric field, when sufficiently intense, can cause a discharge or breakdown of the medium surrounding the charged object.

When two objects with different charges get closer, electrons can suddenly flow from one object to the other.

It is modelled according two different scenarios:

• Human Body Model (HBM): whenever one part of the interaction is a human.

• Machine Model (MM): when the two parts are machines, usually two metallic parts. An example would be when we touch an electronic component of a PCB with a tool.

Nearly all the components have a different immunity level for HBM and MM: it is higher for HMB because the charged body discharges through a ~1500 ohm resistance.

ESD depends strongly also on humidity. Some examples are:

The extreme high voltages can generate very high current peaks flowing through the electronic components, damaging the electronic equipment.

Although that all Keonn’s products have every input-output, power supplies, communication

ports, and RF outputs protected; there could be a level of a charged body that could make the protection to fail.

Therefore it is important to follow some preventive measures.

According to IPC-A-610D, some of the common sources of electrical charge are

PCB handling

Keonn Technologies SL supplies several non-enclosed products, for those products it is absolutely required to follow the above guidelines regarding ESD handling.

Antenna handling

Although antennas itself cannot be damaged by ESD, they can be a source of ESD problems. Antenna Series 100 and Series 200 may become charged, specially when in contact with certain materials with highly electrostatic materials.

• Make sure to follow ESD handling guidelines

• Avoid using non ESD friendly materials as antenna support material.

Connecting an charged antenna to a reader may cause the reader RF port to break.

Two easy ways of discharging antennas are:

• • Connect a load into the antenna before connecting it to a reader

• • Short-circuit the antenna connector live and ground. This can be accomplished by using a finger. Make sure the finger touches at the same time live

IO connectors

Besides antennas, IO connectors are another area where ESD measures must be taken.

• • Make sure cables connected to IO ports are discharged before being connected.

References

Mardiguian, Michel, Electrostatic Discharge: Understand, Simulate and Fix ESD Problems. 2009, Wiley-IEEE Press.

ESD ADV1.0, ESD Association’s Glossary of Terms