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Q and A: Why should I be concerned about essential or non-essential insulators inside my EPA (ESD Protected Area)?

Posted on 12 Sep, 2015

Q: Why should I be concerned about essential or non-essential insulators inside my EPA (ESD Protected Area)?

A:  Insulating materials such as plastics are a common root cause of ESD events.

Many materials are used in and around an EPA.  However, when it comes to ‘static safe’ materials in and around the EPA, there are various points to consider.

Typically, the difference between essential and non-essential insulators is, for example:

Does this this non-static safe plastic component have to be here (is essential) in the EPA, or not (non-essential)?

  • No … then remove it.
  • Yes … how can we remove or reduce the risk of subsequent static damage from electrostatic induction?

Importantly, at the design stage of any product, consideration of the effect of non-static safe materials being built into the product should have already been taken into account.

When an isolated conductor is induced with an electrostatic charge from something like a plastic box, synthetic web, emptying/sliding/peeling operations, wearing inappropriate apparel, etc., it effectively becomes a charged capacitor … waiting to produce an ESD event.

Typical examples are:

Personnel building up a charge from walking or sitting on non-static safe materials.

Populated PCB or ESDS Device stored in or near a non-static safe surface, e.g. box or sheet material.

There are 2 common and very effective methods of controlling electrostatic generating materials:

  1. Ionization / Static Neutralizing – Ionizers are an active method of actually ‘killing’ static by producing +ve & -ve charged free particle in the air; opposite polarities attract and the electrostatic charge is neutralized.

    However, effective ionization is only achieved by correct choice of equipment and application setup.  Incorrect setup can lead to a voltage imbalance and subsequent static problems instead of solutions.
  2. Topical Antistat – this involves spraying, dipping, wet wiping over a surface with a suitable antistat solution.  Once the solution has dried, it leaves an antistatic surface that, until it is rubbed off or degrades with time, prevents the generation & build-up of an electrostatic charge.  

Note – this does not make the surface groundable, but only temporarily antistatic.

Obviously, there’s no ‘one size fits all’ solution, as every application has its own quirks, every solution needs to be tailored to suit.