What is ESD and How Does it Cost Companies Money?

What is ESD?

ESD, or Electrostatic Discharge, is the flow of current between two objects with different electrostatic charges when they come into close contact with each other. This does not mean direct contact, since electrons can bridge gaps between objects.

Electrostatic charges are most commonly created by contact and separation:

  • When two surfaces contact then separate
  • Some atom electrons move from one surface to the other, causing imbalance
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    What Causes ESD?

    There are two different types of materials which can cause ESD: Conductors and Insulators.
    Conductors are materials that can easily transfer electrons/charge and can, therefore, be grounded (charges safely taken away from the object and dissipated safely).

     
     

    Did you know: To feel a static discharge it must be about 2,000 volts. However, a component can be damaged by as little as 100 volts! Therefore, it is very easy for a component to be damaged without even noticing that the event has occurred.

     
     
     
    The problem

    Today, more electronic components are used than ever before and in more compact designs. However, the smaller a component the more sensitive it is and likely to be destroyed/damaged by a sudden surge of static charge.

    If a component is destroyed this is classed as a catastrophic failure and can normally be detected in an inspection and repaired/replaced. However, latent defects pose a larger problem, since this is when a component has become damaged but still operates so the component could pass through the inspection phase and end up being installed in the field.

    Depending on the damage, the consequence of using something with a latent defect in the field may result in an early field failure, which could involve costly repair work for the customer and (if other early field failures occur) a loss of business and reputational damage for the supplier.

    One study calculated the repair costs to fix any failure in a component as:
    £7 if the device fails
    £70 if the device fails on the board
    £700 if the device on the board fails in the system
    £7000 if the system fails due to the device on board

    Therefore, it is important to identify the problem as soon as possible and this may not happen with latent damage. Instead, it would be much easier and more cost effective to ensure that any ESD events are prevented from the start with ESD control measurements.

     
     
     
    How to Control and Prevent ESD Problems?

    An EPA (ESD Protected Area) is an area in which all items with electrical charges are grounded, or made safe by having their charges neutralised. This means that ESD sensitive items can be handled without the risk of ESD charges damaging them.
    There are different levels of protection which can be assigned to an EPA, and this will depend on the amount of time that needs to be spent handling the component and the importance of preventing a field failure. For example, if maintenance in the field is not possible, or safety depends on the product not failing, as with components used in space, medical devices, aircrafts, etc.

    An EPA with a high level of protection will consist of the following:

  • Controlled access to the EPA, which records results and prevents entry to anyone who fails the grounding test.
  • Personal grounding: e.g. smock, heel grounders, wrist straps.
  • Work station grounding: e.g. Mat, ioniser, continuous monitor, ESD floor.
  • If you have any questions about ESD, or you would like help with an enquiry, please do not hesitate to contact us.

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