ESD and Static Control Questions

Q: What is the difference between anti-static and static dissipative floors? Which floor will be better to use if I’m going to have an electronic assembly line?

A: Anti-static is not the proper term to use for ESD flooring.

Anti-Static refers to the ability to suppress charge generation or the prevention of static build up. Anti-static materials will not safely attract or decay a static charge before it randomly discharges. Anti-static material is usually indicated by an electrical resistance range, measured in ohms, of a minimum of 1E10, (10 giga ohms), to a maximum of 1E12, (1 trillion ohms).

ESD flooring systems are referred to as static conductive (more conductive) or static dissipative (not as conductive, but will dissipate charges in an orderly fashion).

Static dissipative floors: 1E06 Ω or 1 Meg Ω to 1E09 Ω. I would consider SD material to be the minimum requirement per ANSI/ESD S7.1-2005 via ANSI/ESD S20.20-2007. If you choose this flooring system, the RTG readings may be at the low end of the scale and be in the E06 to E07 range or it may be at the high end and be in the E08 range. You want to keep you flooring system clean and always below a gig ohm.

Static conductive floors: 2.5E04 Ω to 1E06 Ω. These floors are the superior choice for an assembly environment and offer the lowest charge generation and quickest charge dissipation. These floors require proper cleaning and maintenance, but will likely exceed the requirements for 20.20 throughout its lifetime.

I’d recommend a static conductive flooring system for your application. You are dealing with ESD sensitive components, raw boards, and/or sub-assemblies that have a low threshold voltage tolerance. With a static conductive flooring system and proper ESD footwear, you will have an optimal ESDS area.

Q: We are an explosives manufacturer and are looking to repaint our conductive flooring. We subscribe to the standard NFPA requirements for conductive flooring. What is the best and most economical product to apply? Consider that the environment would be expected to be consistently wet.

A: We recommended (2) possible options, both of which would be completely monolithic and seamless due to the excessive liquids that will be present.
Anytime that you have explosives present, the floor will have to be “sparkproof” and fall into a conductive range, verses static dissipative.
These are the two most important criteria for recommending a system for this environment.

Out of these (2) systems, a conductive epoxy is going to be most cost effective, verse a thermally heat welded conductive vinyl system.

Always best to consider a “professional” or approved factory installation for warranty consideration as well as certification that the floor meets the customers expectations and is actually going to get the job done.

Q: We are removing old vinyl tile and replacing with ESD protective tile. We are wondering if ESD conductive or dissipative is best. Our business is dehydration baking, final functional testing and packaging semiconductor IC’s with design circuits typically in .25 micron range. We need recommendations on conductive vs. dissipative and epoxy vs vinyl tile. The area is not high traffic. Thanks.

A: Good questions. In selecting an electrical range there are several key factors to consider, these are in order of importance in our professional opinion:

1. Device sensitivity?
2. Does the type of work being performed in the protected area include, working with Power Supplies?
3. Is your staff going to be wearing personnel grounding protection?
   • ESD Shoes
   • Heel Straps
   • ESD Booties
   • Etc.
4. Are there any environmental conditions to consider?
5. How important is meeting industry standards to you and your company? e.g.
   • EOS/ESD S7.1
   • ANSI/ESD S20.20
   • ISO Compliance
   • In-House Standards
   • Customer Contract Standards

Based on what you have described in you e-mail, conductive range is best suited for your application, dissipative should not be considered. See the attached white paper on this specific subject. As this particular document has even been published yet, please keep this document confidential for your internal use only.

The factors that should be considered in choosing a Material Type are as follows:

1. What is the intended use for the floor? What type traffic will the floor see? Will liquids or spills be anticipated or utilized in this area? Do you own or lease the building? Will odors be a problem during the installation process? Are you fully operational and or will the work be done in phases? Budgetary factors Performance warranty Maintenance level expectations
2. Esthetics

I think this will give you some things to consider moving forward. Please see the attached floor comparisons chart for additional things you should consider, this chart may prove helpful to you and your team. Let us know if we can provide you with flooring sample submittals, product specification sheets, quotations, etc. I would like to talk to you in greater detail regarding Epoxy vs. Tile, we have many millions of square feet of experience in this category, so please call me when you have some time.

Please let us know how we can better support you and your company moving forward, as your satisfaction is our highest priority!
See also: ESD Open Forum(PDF); ESD Flooring Comparison Chart(PDF)

Q: I am looking for a flooring system suitable for use in a pharmaceutical manufacturing space where Class I-B flammable liquids and vapors are routinely present. Is conductive epoxy the best choice? Is an integral copper grounding grid needed?

A: Yes, Conductive is the correct choice for this type of environment. I’d recommend glancing through our flooring selection chart as a starting point:

Ground Zero Flooring Comparison Chart (PDF)

I’d start with an ESD Conductive floor, whether it be a, Vinyl Tile, Vinyl Sheet, or Epoxy. If you go with vinyl tile or sheet, it needs to have welded seams so it can be chemically sound and completely resistant to spill, etc.

Vinyl Sheet is the most economical option. Vinyl Tile has the highest rated loading at 2500 psi, while Epoxy is most durable. They all have good chemical resistance and excellent permanent ESD performance.

All of our flooring installations incorporate the copper grounding grid tape, this is important to assure a permanent and mechanical path to A/C electrical or structural ground.

Below are some of our examples currently being used in your industry:

ESD Vinyl Tile (Weldable)
ESD Vinyl Sheet (Weldable)
ESD Epoxy

Q: Why can’t bare or sealed concrete be used as a method for controlling static electricity in a electronics manufacturing environment verse utilizing a Conductive or Static Dissipative covering and/or coating?

A: I’ve done some studies on ESD resistive characteristics of the several different floor surfaces. In light of the following question, I just snapped some photos of ESD readings on the following surfaces:

ESD reading on Dry Concrete

Bare concrete (dry). Results- barely conductive, very humidity dependant; in the insulative range(1E09-1E12)

ESD reading on Asphalt

Asphalt. Results- unacceptable; above insulative.

ESD reading on Dirt

Dirt. Results- pretty good, acually comes in at barely dissipative; Upside, cheap; Downside, hard to clean.

Reading on ESD Carpet

ESD Carpet (Ground Zero Information). Results- ESD conductive(2.5e4-1.0E6).

Reading on ESD Tile

ESD Tile (Ground Zero Information). Results – ESD dissipative(1.0E6-1.0E8).

Reading on Sealed Concrete

Sealed Concrete. Results-unacceptable; a sealed concrete is necessary for heavy foot traffic, but the very thing that would make the concrete conductive is sealed out- moisture. This floor could be made dissipative very easily with an ESD chemical (Ground Zero Information).

Reading on Particle Board

Particle board. See asphalt