What is a Faraday Cage?

We have mentioned the term “Faraday Cage” many times on this blog before – for example when talking about the transport and storage of ESD sensitive items or the role of ESD lab coats in ESD Protected Areas. When discussing ESD protection, the concept of the “Faraday Cage” will always come into play. But what exactly is it? Read on to find out…

A Faraday Cage or Faraday shield is an enclosure formed by conducting material or by a mesh of conductive material. Such an enclosure blocks external static and non-static electric fields. Faraday Cages are named after the English scientist Michael Faraday, who invented them in 1836.
An impressive demonstration of the Faraday Cage effect is that of an aircraft being struck by lightning. This happens frequently but does not harm the plane or passengers. The metal body of the aircraft protects the interior. For the same reason, a car may be a safe place during a thunderstorm.

Lightning Striking an AiroplaneLightning striking an airplane

In ESD Protection, the Faraday Cage effect causes charges to be conducted around the outside surface of the conductor. Since similar charges repel, charges will rest on the exterior and ESD sensitive items on the inside will be ‘safe’.
ESD control products that provide a Faraday Cage or shielding include Statshield® Metal-In and Metal-Out Shielding Bags or Protektive Pak™ impregnated corrugated boxes with shielding layer when using a lid.

ESD shielding packaging is to be used particularly when transporting or storing ESD sensitive items outside an ESD Protected Area. Per Packaging Standard EN 61340-5-3 clause 5.3 Outside an EPA “Transportation of sensitive products outside of an EPA shall require packaging that provides both:
dissipative or conductive materials for intimate contact;
– a structure that provides electrostatic discharge shielding.

37150.jpgProtektive Pak® In-Plant Handler

ESD Smocks create a Faraday Cage effect around the torso and arms of the operator and shields charges from the operator’s clothing from damaging ESD sensitive devices. (Technically, suppressing the electrical field from clothing worn underneath).

 

Examples of ESD Smocks

There are standard tests measuring the energy penetration of electrostatic discharges to the interior. The Shielding test method per Packaging standard EN 61340-5-3 is ANSI/ESD STM11.31 and the required limit is less than 50 nanoJoules of energy.

Definitions from the ESD Association Glossary ESD ADV1.0 include: Faraday Cage “A conductive enclosure that attenuates a stationary electrostatic field.
Electrostatic discharge (ESD) shieldA barrier or enclosure that limits the passage of current and attenuates an electromagnetic field resulting from an electrostatic discharge.
Electrostatic shieldA barrier or enclosure that limits the penetration of an electrostatic field.

About Vermason

Vermason is a manufacturer of ESD protection products and was founded in Letchworth in 1979. Our mission is to maintain our position as the primary ESD solutions provider for the electronics industry in Europe. Vermason strive to manufacture quality ESD Control products with innovation, leadership and partnerships which deliver long term commercial benefits. We understand the many challenges our customers face regarding quality and reliability. We support these requirements with products and services of exceptional value which help them gain competitive advantages in their markets. We also appreciate that the control of ESD is one of many necessary links in a long chain required to bring a customer’s project to a successful completion. We endeavour to make that happen. We sustain our vision and mission by constantly seeking renewal via continuous education, application of new technologies and good business practices. Employees are expected to serve the customer with the highest level of technical knowledge in the industry.

Posted on 2016-09-08, in Bags and Labels, ESD Information, Smocks and Shirts. Bookmark the permalink. 1 Comment.

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