The Role of Cleanroom Wipers and Mops in ESD Mitigation

Electrostatic discharge (ESD) can create unintended consequences in cleanroom environments. As discussed in Part 1 and Part 2 of Valutek’s ESD Mitigation Series, managing ESD is essential for maintaining product integrity, meeting cleanliness standards, and ensuring operator safety.

From degrading sensitive microelectronics to attracting airborne contaminants, uncontrolled static electricity poses a wide range of risks. For example, static charges can attract particulates onto critical surfaces, or the smallest shock can damage sensitive electrical components. Both ESD events can lead to defects, compromised performance, and reduced yield.

Building an Effective ESD Control Strategy

Mitigating ESD isn’t about relying on a single product. It’s about building a fully integrated ESD mitigation strategy. Ionizing bars, humidity controls, conductive flooring, compliant garments and properly engineered consumables must all work together. Even one non-compliant component can undermine a cleanroom’s ability to effectively reduce ESD risk.

In Part 3 of Valutek’s ESD Mitigation Series, we focus on how critical contact consumables like wipers and mops can either help reduce or unintentionally introduce ESD risks, depending on how they’re made, packaged, and used.

Understanding Key ESD Terms

Before diving into product specifics, it’s important to understand four key terms related to ESD control:

• Anti-Static: Reduces or suppresses static buildup but doesn’t actively conduct charges away.
• Dissipative: Allows static to discharge safely and slowly.
• Conductive: Allows charges to flow quickly and easily, immediately neutralizing static.
• Insulative: Prevents charge movement entirely, causing static to build and remain. Generally avoided in cleanroom applications.

The Role of Packaging

One of the most common ways static is created is through triboelectric charging. This is when two materials come into contact and then separate, creating friction. Think of walking across carpeted flooring in socks, then touching a doorknob. That same friction can occur during the packaging and shipping of cleanroom wipers.

If wipers are loosely packed, they may rub against each other and their packaging material during shipping, arriving at your facility already carrying a static charge. A “hot wiper” can then attract particles or, worse, discharge static onto sensitive components.

Packaging design matters! Flat-packed, vacuum-sealed, and double-bagged wipers reduce movement during transit and help ensure they arrive clean, dry and static-neutral.

Substrate Selection: Polyester vs. Polyester-Cellulose

Cleanroom wipers are typically made from either 100% polyester or a polyester-cellulose blend, often referred to as “nonwoven.” While both are suitable for a range of cleanroom environments, their ESD properties differ, especially when used dry.

• Polyester is naturally insulative, meaning it resists electrical flow. Though clean and durable, untreated polyester is not ideal for ESD-sensitive applications.
• Polyester-Cellulose blends tend to be dissipative when dry, making them more ESD-friendly. However, they may generate more particle shedding, creating a tradeoff between cleanliness and static control.
  
  

Pre-saturated Wipers: A Smart Solution for Static Control

Most cleanroom wipers are used wet, and once saturated with a cleaning solution, their ESD behavior improves significantly. Aqueous liquids function as conductive media that enable safe static dissipation.

While it is possible to wet dry wipers on-site using squeeze bottles or spray applicators, this manual method can lead to inconsistent saturation levels. Uneven saturation may leave parts of the wiper dry, reducing its ability to neutralize static charges.

Pre-saturated wipers offer a more reliable and controlled solution. Professionally manufactured and packaged, these wipes are uniformly saturated, removing the guesswork and variability from wiper to wiper.

High quality pre-saturated cleanroom wipes can:

• Clean surfaces without leaving behind residues, particles, or static contamination.
• Help neutralize surface charges on workstations, tools, equipment, and packaging.
• Reduce the risk of particle attraction and charge buildup during cleaning.

For ESD-sensitive environments, pre-saturated wipes are the superior option, particularly when paired with high-purity solvents and ESD-conscious packaging.

What About Cleanroom Mops?

Cleanroom mops are essentially large-format wipers attached to handles – used for cleaning floors, walls, and ceilings. In most ESD-sensitive facilities, the cleanroom floor is either inherently conductive or treated to be ESD-safe with a topical coating.  Even so, mop material, construction, and cleaning chemistry play a role in ESD management.

Because mops are typically used wet, the saturation level and solvent chemistry greatly influence their effectiveness in static control. In addition, Valutek mop heads are designed with a carbon weave near the bridge, which provides additional ESD mitigation by allowing static to dissipate from the mop, through the handle and operator, and into the floor. Selecting the right mop system can support effective static mitigation during routine cleanroom cleaning.

The Valutek Difference

While many manufacturers supply cleanroom wipers and mops, Valutek has options that are designed with ESD mitigation in mind.

• Flat-packed, vacuum-sealed, and double-bagged packaging minimizes triboelectric risks during shipment.
• Specialty polyester ESD wipers woven with conductive carbon fiber are available for high-risk applications that require a clean, dry, ESD-safe wiper.
• Customized pre-saturated wipers, made to order with any chemistry, provide maximum control over your cleanroom’s ESD strategy.

ESD Control is a System, Not a Single Product

Selecting the right mops and wipers is essential for meeting cleanroom specific ESD requirements, but it’s just one part of a larger system. A truly ESD-safe environment includes conductive flooring, ionization systems, static monitors, humidity controls, grounded workstations, and critical cleanroom consumables that are thoughtfully selected, properly packaged, and appropriately used.

Since wipers and mops are in direct contact with cleanroom surfaces, products, and processes, they’re essential components of your ESD control strategy.

Explore Valutek’s full line of ESD-compliant consumables or contact our technical team for help choosing the right products for your application.

EXPLORE MORE RESOURCES:

• Shocking: Mitigating the Risk of ESD in Controlled Environments

• The Power of Proper Grounding: ESD Shoe Covers for Controlled Environments