05 Dec

People are a great generator of static electricity

Q: How does ESD Gloves, Aprons and Bunny Suit help for static discharge? WIll it not be mandatory to wear the wrist band, footwear and heel strap along with it?

A: People are a great generator of static electricity, among other things. The ESD gloves, aprons, etc. enable you to work and interface with sensitive components and equipment while protecting them from an ESD event as well as other things like contamination from human skin, street clothes, dirt, dust, etc. It will be mandatory for personnel ground to wear a wrist strap when in seated operations in a manufacturing environment or in the field. For personnel ground in an environment where you are standing or walking about, you do NOT have to wear a wrist strap if you have sufficient ESD footwear in conjunction with an ESD flooring system. The above requirements are per ANSI/ESD S20.20-1999 Table 1.

05 Dec

ESD Garments in addition to Wrist Straps and Footwear/Grounders

Q: Is it necessary to use the ESD garments? Is it not possible to ground the charges developed through a person’s clothing through the human body which is grounded through a wrist strap, footwear or heel strap while working at an EPA?

A: This depends who’s in charge.  If the ESD manager wants to require ESD personnel clothing and redundancy of ESD compliance for improved ESD control, they are the one to determine that.  More and more I’m seeing the use of ESD smocks outside of the cleanroom environment.  The company and their clients are reaping the benefits of increased quality control and reduced “out of box failures”.  Cloth is proven to be a better conductor of ESD charges than some types of clothing, but not everybody wears cotton.  Some people have dry skin and the ESD garments are a good idea for added protection and a requirement in some environments.

I’d like to add that when seated in an EPA, you must have your wrist strap on regardless of ESD Garments, ESD footwear, ESD flooring system, etc.  That’s a requirement of ANSI/ESD S20.20-2007 page 4 section 8.2 Personnel Grounding; “When personnel are seated at ESD protective workstations, they shall be connected to the grounding/equipotential bonding system via a wrist strap system.”

Further, per Table 2 note 2, “For situations where an ESD garment is used as part of the wrist strap grounding path, the total system resistance including the person, garment and grounding cord shall be less than 3.5E7 ohms.”

05 Dec

Using an ESD Chair when already protected

Q: Is it necessary to use an ESD Chair when the humany body is already grounded through a Wrist Strap, Footwear or Heel Strap when working in an EPA?

A: I think it’s a great idea.  I can be sitting at a workstation with an ESD flooring system, have a wrist strap on and when I get out of my chair, not generate more than 50 volts.  I may not generate more than 5 volts.  But what if I take my wrist strap off and jump out of my chair?  I can easily generate 100’s of volts.  Oh, by the way, jumping should not be allowed in an EPA.  If you have great ESD shoes or sole grounders and you keep at least one foot firmly planted on the ground at all times, then maybe your ESD chair is redundant, but still an added piece to the chain in your EPA system.

05 Dec

What does ASTM F2413-05 compliant mean?

Q: What does ASTM F2413-05 compliant mean?

A: I’ve got the document from the American Society for Testing and Material Standards (ASTM) in front of me now.

They sent me a copyrighted document on June 2nd of 2005.

It’s significance and use section is pretty encompassing;

  1. This specification contains requirements to evaluate the performance of footwear for the following:
    1. Impact resistance for the toe area of footwear.
    2. Compression resistance for the toe area of footwear.
    3. Metatarsal protection that reduces the chance of injury to the metatarsal bones at the top of the foot.
    4. Conductive properties which reduce hazards that may result from static electricity buildup, and reduce the possibility of ignition of explosives and volatile chemicals.
    5. Electric shock resistance.
    6. Static Dissipative (SD) properties to reduce hazards due to excessively low footwear resistance that may exist where SD footwear is required.
    7. Puncture resistance of footwear bottoms.
    8. Chain saw cut resistance, and
    9. Dielectric insulation.

There’s a section in there that describes Performance Requirements and Workmanship, Hazard Assessment, Labeling and Identification, Marking and Compliance Requirements, and Keywords.