How do you Neutralize a Static Charge on Something that Cannot be Grounded?

Wrist straps and work surface mats are some of the most common devices used to remove static charges. Wrist straps drain charges from operators and a properly grounded mat will provide path-to-ground for for exposed ESD susceptible devices . However, what if the static charge in question is on something that cannot be grounded – an insulator or isolated conductor? All electronic products consist of conductors and insulators. And insulators and isolated conductors can be items used at the workstation such as hand tools, packaging materials, or fixtures.

The ESD Association’s ANSI/ESD S20.20 requires insulators/isolated conductors that charge to:

  • 125 volts or more be kept 1 inch or more away from ESD sensitive items.
  • 1000 volts or more be kept 12 inches or more away from ESD sensitive items.
Desco ionizers

Move insulators away if possible

How are insulators/isolated conductors that cannot meet these requirements controlled?

There are 3 options available for handling insulators/isolated conductors in an EPA:

  1. Move the insulators/isolated conductors beyond the 1 inch and 12 inch requirements from ANSI/ESD S20.20 2014
  2. Replace the non-ESD version of insulators/isolated conductors with an ESD protective version of insulators/isolated conductors.
  3. Use air ionization to neutralize charges on insulators/isolated conductors.

Air ionization

Desco

Insulators and isolated conductors are common in ESD Sensitive (ESDS) Devices

Most every ESD workstation will have some insulators/isolated conductors that cannot be removed or replaced and could be addressed with ionization. These insulators/isolated conductors that cannot be removed are called: process-required. Common process necessary insulators/isolated conductors include product housings, screens, specialized components, or unique sub-assemblies. The charged ions created by an ionizer will:

  • neutralize charges on process required insulators
  • neutralize charges on non- essential insulators
  • neutralize isolated conductors
  • minimize triboelectric charging

The  maximize discharge time for neutralizing 1,000 volts to 100 volts is user definable per ANSI/ESD S20.20. A good starting point for most standard ESD susceptible items is <7 seconds. But, the faster, the better.

Content courtesy of Desco

For more information on Air Ionization please contact us at Orders@murraypercival.com

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Murray Percival Company offers thousands of capital and consumable products for virtually every facet of printed circuit electronics assembly and repair. With more than 60 manufacturers to choose from, Murray Percival Co. is ready to take on your challenges with technical information, and over 59 years of experience in the circuit board manufacturing and repair industry. We have a multi-state technical sales force, as well as, on-demand shipping to anywhere in the continental United States. Our "We Know How" knowledge base provides in-depth support information for many of our products. We also offer competitive specialty pricing for customers that register on our Web Store.

Posted in ESD Protection, Latest News, PCB Rework

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