IEC 61000-4-2: Electrostatic Discharge Immunity Tests

Article

Testing for immunity to electrostatic discharge (ESD), from cell phones to computers, is usually done with the IEC 61000-4-2 standard.1 But IEC61000-4-2 is purely a systems-level test spec, not a spec for individual components. Read more...

ESD Background

Electrostatic Discharge (ESD) is the abrupt release of charge from one object (often a person) to another. Such a discharge can permanently damage or otherwise upset the function of sensitive electronic circuits.

Electronic products are tested for ESD immunity to insure their continued reliable operation if subjected to realistic levels of ESD after being placed in service. The European Union’s EMC Directive mandates ESD immunity testing for virtually all electrical and/or electronic products as a condition for obtaining the CE Mark before shipping to a member state of the European Union.

Applicable Standards

Generic Immunity Standards, Product Standards and Product Family Standards require that ESD tests be performed in accordance with specific Basic EMC Standards: IEC 801-2, IEC 61000-4-2, or EN 61000-4-2. Thermo KeyTek’s Application Note, “EMC Standards Overview,” provides an overview of European Standards for electromagnetic compatibility, describes how the Standards relate to one another, and lists sources for procuring copyrighted documents.

Basic EMC Standard

The Basic EMC Standards for ESD define methods of generating consistently reproducible electrical stresses for test purposes. They specify capacitances and resistances to model the human body’s charge storing capability and discharge impedance, respectively. This model results in a current waveform, defined in the Standards. While the Basic EMC Standard also specifies how to perform ESD testing, the Generic, Product and Product Family Standards specify the test levels and pass/fail Performance Criteria.

General Testing take place in climatic specification as follows:
Ambient temperature :               15°C to 35°C
Relative Humidity :                     30% to 60%
Atmospheric Pressure :              86kPa (860 mbar) to 106kPa (1060 mbar)
Other values may be specified in the test specification.

• A ground reference plane (GRP) is required.
• The EUT shall be positioned at least 1 meter from walls and metallic structures.
• Positioning of power and signal cables shall be representative of good installation practice.
• The EUT shall be conected to a grounding system, representative of good installation practice; no additional earthing connecions are allowed.
• The discharge return cable should, where possible, be placed off the ground reference plane, and should not come closer than 0.2 meters to other conductive parts of the test setup.
• Vertical Coupling Planes (VCP) and Horizontal Coupling Planes (HCP) max be used for indirect application of the ESD pulse. These planes shall be constructed from the same material and thickness as the ground plane, and should be connected to the ground plane by a cable with two 470kohm resistors, one resistor at each end of the cable.
• For tabletop equipment, a non-conductive table 0.8 meters high is placed on the ground plane. A ground plane (HCP) 1.6 meters by 0.8 meters will be put on the table, and the EUT and any cables shall be placed on an insulating support 0.5mm thick placed on top of the HCP. The HCP shall be connect to the ground reference plane with a resistive cable as in previous paragraph.