ESD-safe cotton buds prevent damage to circuit boards caused by electrostatic discharge

Cotton swabs are useful precision tools for technicians and operators to perform delicate and meticulous tasks such as precise cleaning, repair and assembly. Types of cotton swabs range from inexpensive cotton swabs on wooden sticks to sophisticated cleanroom materials with specialized head designs. However, there is an often unstated risk when using cotton swabs on sensitive electronic circuit boards - electrostatic discharge (ESD).

What is electrostatic discharge (ESD)?

As defined by the EOS/ESD Association, ESD is "the rapid, spontaneous transfer of electrostatic charge induced by a strong electrostatic field... Normally, the charge flows through a spark between two bodies with different electrostatic potentials when they approach each other."

Electrons are constantly exchanged when objects come into contact with each other. Problems arise when the materials involved do not easily allow the flow of electrons and equilibrium is not achieved. These materials are known as insulators and tend to collect electrons, which form negatively charged "hotspots" on their surface.

When these charged hotspots come into close proximity (not necessarily direct contact) with another object, a sudden exchange or "discharge" can occur, where electrons are suddenly exchanged to restore balance. This event is called an "electrostatic discharge" or "ESD".

Electrostatic discharge happens all the time, especially in dry climates and during the winter months when there is no moisture in the air to dissipate the excess electrons (water is conductive and allows electrons to flow more easily). Normally it is nothing more than a nuisance, but with sensitive electronics it can cause circuit board failures.

When handling insulating materials such as typical polypropylene cotton bud handles, a worker can generate thousands of volts. SMOS logic devices can be damaged by as little as 250-3000 volts, EPROM devices by 100 volts, and microprocessor chips by as little as 10 volts. Damage can disrupt functions or cause intermittent problems, and it can be either catastrophic (immediate) or latent (later, e.g. as a "field failure"). (Source: Phil Storr's PC Hardware Book)

How do standard cotton buds generate electrostatic discharge (ESD)?

If the cotton bud head is impregnated with a solvent, the static charge can be avoided as the liquid is often conductive. The handles of cotton buds, on the other hand, are often made of synthetic materials and tend to generate and store a static charge. Cotton bud handles are often made of polypropylene or nylon, both of which are insulating.

As the fingers and hand come into contact with the cotton swab handle, the friction creates a static charge. These excess electrons collect on the material of the handle and do not flow easily to earth, even if the operator wears a wrist strap.

When natural materials are used to make the cotton swab, such as wooden sticks and cotton headed cotton swabs, static electricity is less of a problem. These materials are generally considered "static neutral" as they easily absorb ambient moisture from the air, which helps to prevent static build-up and discharge.

This table provides a brief overview of the different types of cotton buds, their areas of application and the special features of each model:

Coventry™ ESD Control cotton buds

ESD-safe cotton swabs are available from Coventry™, the premium cleanroom brand from Chemtronics®. The cotton swab handles are made of a proprietary static dissipative material that allows excess electrons to flow away. So when the operator is grounded with a wrist strap, hot spots and electrostatic discharges are avoided.

Static dissipative (Coventry ESD Control cotton swabs) - surface resistivity at least 1 x 10^5 Ohm/sqm, but less than 1 x 10^12. Electrons flow easily to avoid both sudden discharges and charged hotspots.

Insulating (standard cotton bud handles) - surface resistivity at least 1 x 10^12 Ohm/sqm. Electrons do not flow easily, so that charged hotspots can form on the cotton bud sticks.

With a total of 12 variants of ESD Control cotton swabs, the Coventry cotton swab range offers the ability to replace all the cotton swabs currently used in your facility when handling sensitive electronics. While these cotton swabs are typically more expensive, the price is negligible compared to the cost of PCB failure issues, rework, product returns and loss of customer confidence.

We offer a large selection of swabs and cleaning sticks, both online and outside of our store. In our range you will find ESD-safe and non-ESD swabs in various shapes and sizes, which are suitable for a wide variety of applications - whether for cleaning sensitive electronics or for other specialized tasks.

Please note that we carry many other products that are not displayed in our online store. If you are looking for something special, we will be happy to help you.

Do you have any questions or need help choosing the right product? Our team is here for you and will be happy to help!