October 05, 2021



Pink ESD foam has been a standard in the world of ESD packaging since its creation in the seventies. It's a fantastic product that meets many needs in many situations. Pink foam has typically been used as a cushioning aspect of packaging or work surface and has been a “solution” for many shortcomings. That said, there has been a misconception of the anti-static properties and how long they last. Pink anti-static foams have a shelf life. Once that shelf life is over, the foam can be quite dangerous to the manufacturing environment and sensitive components. Looking closer at an EPA (ESD Protected Area), the the use, or misuse of these foams is the most commonviolation of standard ESD practices.

As it relates to ANSI/ESD S20.20, ANSI/ESD S541 tells us in 6.1 and 6.2 that packaging (in this case pink foam) used inside and outside an EPA has to have certain characteristics.

6.1 Inside an EPA

Packaging used within an EPA (that satisfies the minimum requirements of ANSI/ESD S20.20) shall be:

  • Low charge generation.
  • Dissipative or conductive materials for intimate contact.
  • Items sensitive to < 100 volts human body model may need additional protection depending on application and program plan requirements.

6.2 Outside an EPA

Transportation of sensitive products outside of an EPA shall require packaging that provides:

  • Low charge generation.
  • Dissipative or conductive materials for intimate contact.
  • A structure that provides electrostatic discharge shielding.
White paper on pink foam
A Conductive corrugated front-lock mailer utilizing die-cut pink anti static foam

One of these characteristics states that materials used must be low charge generating. Foam is used for "intimate contact" in most applications. That is why it is so vital to understand what makes Pink ESD foam static dissipative and why it has a shelf life. When the shelf life has been expired, you just have regular foam. In order to better understand the “shelf life,” we first need to look at regular foam in general, ESD foam, and where it can and cannot be used.

Foam Is Great For Cushioning

As a substrate, regular foam provides fantastic cushioning to protect items from physical harm. The concern with regular foam is that it is very high on the triboelectric scale and has a high likelihood to produce a static charge. All materials, even conductors, can be tribo-electrically charged. How much charge is affected by material type, speed of contact and separation, humidity and several other factors. Therefore, regular (non ESD) foam is cannot be used in an EPA (ESD Protected Area) environment. Remember, when the ESD properties expire from the Pink ESD Foam, you just have regular foam left.

Pink Anti Static Foam

By the nature of its high surface area and chemical composition, flexible foam is subject to the acumulation of static charges. This property is addressed with the addition of anti-static chemical additives or anti-static surfactants. These additives are most commonly added to the foam during manufacture. The color pink is just what the industry chose to help identify the foam as “ESD” or “Antistatic” materials.

The surfactants used are low molecular weight fatty acids commonly based on amides or amines. Surfactants are mobile (blooming) surface modifiers that temporarily change the friction properties between mating surfaces (tribo charging). This is a pretty substantial statement. Now, let's look closer to help understand it better. The surfactant molecules are unsaturated in their initial state.

These molecules have unsaturated bonds that want to absorb moisture. In the unsaturated state, they help lower the friction of the foam which helps its Antistatic properties. The challenge of unsaturated molecules is their main goal in life is to become saturated. Once the molecule is saturated, the game is up and the antistatic properties are done. How long until these molecules to become saturated? That varies depending on many factors. Humidity and the environment play a vital role.

The handling of the foam plays a vital role. In reality, there is little actual guideline for how long it takes to saturate. Many industry experts determine one year as the date to begin testing while others test earlier and some later. It boils down to your understanding and your procedures. What works for some might not work for all.

Shelf Life

And now we know why foam has a shelf life. Once its shelf life has expired, foam will not appear to be any different, but its ESD protective properties will be gone. We also know that, based on many factors, shelf life can be short or long. So what do we do?

It's a good thing that the ESD Association has provided us a guide to help address this problem. ANSI/ESD S541 tells us in 6.1 and 6.2 as it relates to ANSI/ESD S20.20 that packaging (pink foam) used in- and outside an EPA is required to meet certain characteristics. One of these characteristics is that materials must be low charge generating. It also says that for intimate contact of sensitive products, it must be dissipative or conductive.

Foam is often used for intimate contact of sensitive products. You see foam lining racks and shelves, in bottom of drawers, in totes and as separators between stacks of circuit boards or assemblies. This makes sense. We cannot have any charge generating packaging material in an EPA or in specific scenarios outside of an EPA.

And now we have an issue. We have outlined and explained how these foams might or might not be static safe. If the foam still meets its material specifications, we are all set. If the properties of pink foam are gone, what can you do? Lucky for us, we again can turn to the ESD Association for guidance. More specifically, ANSI/ESD S541. In section A.6:

The static control properties of some packaging materials can deteriorate with time and use. Compliance Verification of static control packaging properties should be part of the ESD control compliance verification plan.

A6 Compliance Verification

This is an important statement. It both validates that material deteriorates over time, it also states that we must have a verification process to be sure the properties are still good to go. Another reference to validate this is ESD TR53-01-06. This document discusses compliance verification of ESD protective equipment and materials.

Permanent static dissipative and conductive foams are an option to replace pink foams when shelf life is a concern.
Innovative permanent static dissipative bubble designs can eliminate both ESD and FOD issues
Innovative permanent static dissipative bubble designs can eliminate both ESD and FOD issues in long-term use applications.

Package Compliance Verification

Periodically validate packaging materials as recommended in ANSI/ESD S541 (Packaging Materials for ESD Sensitive Items). Considering the large variety of materials used in packaging, users should create their own plan for verification of packaging compliance.


FOD (Foreign Object Debris)

One last thing to consider when using foam for intimate contact with electronics is the concern about FOD – foreign object debris. All foams, regular non-ESD foams, antistatic foams, and conductive foams will shed particulates to varying degrees. Some are much better than others, but foam will create some FOD. If you’re wondering about FOD when handling devices, use alternate options to avoid contact with foam.



So here we are. We have discovered that you might have a problem if you're using Pink ESD Foam.

  • Pink ESD Foam has a shelf life
  • The shelf life of that foam varies
  • When foam loses its ESD properties, it is unacceptable in, and potentially out, of an EPA
  • If you're using Pink ESD Foam, it should be a short term solution
  • Consider the potential FOD issues with foam
  • Have a quality program in place if you are going to use foam long term

Thanks to the ESD Association, there's a potential solution to the issue of limited shelf life. Compliance verification can make an antistatic foam viable. Without compliance verification, or if it isn't practical, then other more permanent options should be used.