What is an ESD Protected Area (EPA)?

We’ve mentioned the term “ESD Protected Area (EPA)” many times in previous blog posts but what exactly is it?

  • Why do you need an EPA?
  • How can you identify one?
  • And most importantly what do you need to create an EPA?

This posts will help shed some light on these very common questions so let’s go!

Definition of an ESD Protected Area (EPA)

An ESD Protected Area (EPA) is a defined space within which all surfaces, objects, people and ESD Sensitive Devices (ESDs) are kept at the same electrical potential. This is achieved by simply using only ‘groundable’ materials (i.e. materials with an electrical resistance typically of less than 109 ohms) for covering of surfaces and for the manufacture of containers and tools. All surfaces, products and people are bonded to Ground. Bonding means linking, usually through a resistance of between 1 and 10 megohms. Movable items (such as containers and tools) are bonded by virtue of standing on a bonded surface or being held by a bonded person. Everything that does not readily dissipate charge must be excluded from the EPA.

Components of an EPAExample of an EPA

The user guide CLC/TR 61340-5-2:2008 defines an EPA as follows:
An ESD protected area (EPA) is an area that is equipped with the ESD control items required to minimize the chance of damaging ESD sensitive devices. In the broad sense, a protected area is capable of controlling static electricity on all items that enter that work area. Personnel and other conductive or dissipative items shall be electrically bonded together and connected to ground (or a common connection point when a ground is not available) to equalize electrical potential among the items. The size of an EPA can vary greatly. A protected area may be a permanent workstation within a room or an entire factory floor encompassing thousands of workstations. A protected area may also be a portable worksurface or mat used in a field service situation.” [CLC/TR 61340-5-2:2008 Use guide clause 4.6 Protected areas (EPA)]

An EPA could be just one workstation or it could be a room containing a number of different workstations.
So to sum-up, in an EPA you:

  • ground all conductors (including people),
  • remove all insulators (or substituting with ESD protective versions) or
  • neutralise process essential insulators with an ioniser.

Purpose of an ESD Protected Area (EPA)

Electrostatic Discharge [ESD] can damage components and products containing electronics. It is the hidden enemy in many high-tech factories. Often this damage cannot be detected by quality control inspections which can be very frustrating. ESD damage can adversely impact productivity, quality, product reliability and thus a company’s reputation and profitability.
An EPA is an area that has been established to effectively control ESD and its purpose is therefore to avoid all problems resulting from ESD damage. Operators need to understand and follow the basics of ESD control to limit the generation of electrostatic charges, limit and slow discharges in the EPA.

Identifying an ESD Protected Area (EPA)

An EPA needs to be identified as such. You can use products such as floor marking tape and/or signs which are designed to attract attention and deliver a clear message to personnel and visitors, i.e. “You are entering an ESD Protected Area” or “You are leaving an ESD Protected Area”.

EPA Sign
Example of an EPA Warning sign

Creating an ESD Protected Area (EPA)

In its simplest form, an EPA area is a basic workstation and consists of the following components:

  • an ESD working surface mat,
  • a grounding cord,
  • a wrist strap,
  • a coiled cord and
  • an Earth Bonding Point Plug (EBP Plug).

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Set-up of a basic EPA – watch the video

To create an EPA:

  1. Bond the operator to the EBP Plug using the wrist strap and coiled cord.
  2. Connect the ESD working surface mat to the EBP Plug using the grounding cord.

By following the above two steps, each element connected to the EBP Plug (the surface and the operator) are kept at the same electrical potential and any electrostatic discharge (ESD) is being removed to ground via the EBP Plug. The EBP Plug provides a common ground point for grounding using protective earth. The plug fits into the mains supply socket, making a connection with the earth conductor only. In place of the live and neutral pins are moulded insulating plastic pins to allow positive location in the socket.

Do you have any questions for us? Let us know in the comments!

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 2016-05-26, in Articles, ESD Information, How-To. Bookmark the permalink. 7 Comments.

  1. Ivan Castró

    What type of measurement is to be taken to verify that the ESD bag complies with the rules ?, which cerificación this study supports me and who is the authority to issue the document.

    • Hi Ivan – thanks for your question. The measurement you need to take is the Point-to-Point Surface Resistance (Rp-p). We recommend measuring the inner and outer surface of the bag. You can use a Surface Resistance Test Kit like Vermason units 222635 or 222642 to take this measurement. Whatever unit you are using, you need to have 2 probes (electrodes) that are compatible with the tester. You will need those to perform the Point-to-Point Surface Resistance. This test will ensure the bag is within the limits of EN 61340-5-1 and Packaging standard IEC 61340-5-3. The value for the Point-to-Point Surface Resistance needs to be 1 x 10^4 to < 1 x 10^11 ohms to be within the limit. Let us know if you have any other questions.

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