Conductive vs. Dissipative Materials
In the mid-1820’s, Georg Ohm, a self-taught mathematician and physicist, began doing experiments in the newly discovered field of electromagnetism. Hoping to advance his stalled career, he used the work of Hans Christian Ørsted as a jumping off point, discovering an inverse mathematical relationship between current and resistance.
Georg Simon Ohm
Unfortunately, in an effort to make his theories more understandable to non-mathematicians, he managed to alienate the scientific community and his groundbreaking work went unrecognized for almost 15 years.
Today, he’s remembered by the law that bears his name and its legacy, the standardized unit by which we measure electrical resistance – the Ohm (Ω).
Electrical Resistance: The Water in Pipe Analogy
To put it simply, what Ohm had discovered, but failed to adequately communicate, is that electricity acts like water in a pipe. In this analogy, resistance tells us how wide or narrow the “pipe” transmitting the electricity is.
When two items touch each other, they create an electrostatic charge – one item is positively charged, and one negatively charged. When the items are separated, it creates a triboelectric effect – a buildup of potential energy which can result in an electrostatic discharge (ESD).
In our quest to prevent ESD, which can be damaging and potentially catastrophic to sensitive electronics and circuitry, there are several approaches that vary, depending on the situation.
To illustrate those, we go back to Ohm’s electrical “pipe.”
At the narrowest end of the pipe, we have insulative materials – wood, carpeting, plexiglass. Insulative materials prevent or severely limit the flow of electrons across their surface.
While it may seem that this is the highest and best protection, the opposite is actually true. Because insulative materials are self-contained, they do not ground – meaning the potential energy continues to build up without going anywhere, until it comes into contact with another object, at which point, the new item is bombarded with the electrostatic discharge.
At the widest end of the pipe, we find the conductive materials – copper, steel, water. Conductive materials offer almost no resistance to electrostatic discharge. The electrical charge moves quickly through the materials – too quickly, which can lead to significant problems, as well as safety hazards.
In between these two extremes are the two materials most often used for ESD storage containers, matting and flooring: static conductive and static dissipative.
Towards the wider end of our metaphorical pipe, we find static conductive materials. Because of the low electrical resistance, electrons flow easily across the surface, and can be grounded safely. Typically, static conductive materials are most often used for ESD flooring.
Towards the narrower end of the pipe we find static dissipative materials. The higher resistance of these materials keeps the electrical charge more under control as it slowly flows over the surface and into a ground. Static dissipative materials are much more commonly used for ESD prevention and can be found in table top mats, ESD shoes and some flooring.
For storage containers – boxes, bins & totes – both conductive and dissipative materials can be used, depending on individual needs. Just keep in mind that dissipative materials have a higher resistance than conductive materials.
For more information, or an even more technical discussion of the properties of ESD materials, contact us today. We would love to be your full service, seamless ESD solution provider.