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Topics Covered
Overview
ESD Applications and Products
ESD Materials
While the market for electrostatic discharge (ESD) coatings, materials, and devices is growing with the proliferation of electronic devices and components, an even more exciting development is the introduction of new, high-tech materials into the ESD marketplace. In addition to the "old guard" of antistatic materials--metals, ITO and other metal oxides, carbon black- and carbon fiber-filled composites, and organic materials such as amines, amides, and esters--we can now add more advanced materials like nanoparticles of metals and metal oxides, carbon nanotubes and graphene, and conductive polymers like PEDOT:PSS. These newer materials introduce new capabilities for improved performance, reduced material usage, and greater ease of ESD protection that will bring new life into a mature industry. These are the new face of ESD materials and will account for a rapidly growing share of this market.
There is a diverse range of ESD products but many of them can be categorized by their function. These include: packaging products, including bags, totes, and shipping containers that protect sensitive devices contained within them; products designed to create a static-free local environment, such as flooring, mats, furniture, and clothing; and coatings and other shielding designed to provide permanent protection of an enclosed or covered device. There are also additives for fuels and other fluids, ionizing devices designed to neutralize static charges on demand, devices for monitoring ESD protection, and more mundane devices like grounding cables.
Within these functions, ESD protection can be divided into two different, but often complementary, goals. One goal is to eliminate static charges when they occur. This can be done simply by rapidly conducting them to ground or, often more effectively, by dissipating the charges, or "inefficiently" conducting them to ground, converting much of the electrical energy to heat in the process. The other goal is to prevent the generation of static charges in the first place. Static charges are often generated by the triboelectric effect, simply by rubbing or separating surfaces, which causes the transfer of electrons. This triboelectric generation is common with typical plastics, glass, and other insulating materials; antistatic materials are designed to be less prone to it.
Generally, the most sensitive ESD applications are those involving direct contact with sensitive electronic components, and these are typically in electronics manufacturing and assembly operations. ESD protection is an integral part of the design of every piece of equipment or other part of a wafer fab, for instance, and is of paramount importance in circuit board and device assembly and in the handling of electronic components. The ESD products used in these environments add up quickly. At the wafer fab level, millions of square feet of fab flooring are used in addition to the containers for the wafers, the tools handling them, and the garments for the workers. And at the assembly level, the ESD products add up similarly, but now include ESD bags and other packaging materials for components and boards. Even the smallest PC upgrade outlets must use an ESD system, including an ESD-protected work area, ESD bags, and grounding of the workers, to minimize component and device damage due to ESD.
As the most sensitive devices shrink to smaller circuit dimensions and lower operating voltages, they also become increasingly sensitive to ESD. Combined with the growth in the number of devices, especially handheld devices like mobile phones and music players, ESD requirements will grow along with the volume of these products, yet face increasingly more demanding performance requirements and rising cost sensitivity.
Beyond these products, which are designed to protect electronic components, there are also others, many used outside the electronics industry. Grounding and antistatic systems for fuel pumps and airline fuel delivery systems, including antistatic additives widely used in jet fuel, are another important application area, the main focus of which is on preventing fires rather than on damaging electronic components. Here, volumes of ESD products are likely to be impacted more by changes in regulatory requirements than by the competing, gradual trends of increasing numbers of fuel-burning vehicles and increasing fuel efficiency.
There is something of a "changing of the guard" beginning in the field of ESD materials. Conventionally the materials used for ESD applications have been metals--a metallic stripe or wire included within a non-conductive bulk material, forming a network-or carbon-filled materials such as plastics containing carbon black or carbon fibers. There have also been metal oxides--ITO and tin oxide, mostly--used where transparency is important, and somewhat conductive organic compounds including quaternary ammonium salts, amines, amides, and esters. But the newer conductive materials, nanomaterials and some conductive polymers, that are finding their way into many sophisticated applications are also finding niches in the less glamorous applications including ESD materials.
These include materials like metal nanoparticles, either applied as the main ingredient in a coating or as a conductive filler in a bulk material like a plastic that is otherwise insulating. The small size of nanoparticles combined with the low conductivity requirements of ESD materials offers the potential to use such small amounts of metals that even an expensive metal like silver is not cost prohibitive. (This potential has not yet been realized because of the still high cost of nanomaterial manufacturing.) Nanosilver has received most of the attention for the more conductive applications because it is so much more conductive than any of the other nanometals under actual use conditions--largely because silver's oxide, unlike those of other metals, is conductive--but for ESD materials other metals may also come into play. ESD materials, and especially dissipative ones, permit and even require higher resistivity than most other applications and the presence of some insulating oxide may not be a big problem.
Also promising is carbon in the form of carbon nanotubes, which can be used in even smaller quantities and which are not inherently expensive; their high cost is due to their newness. Carbon nanotubes, some of them anyway, are more conductive than any metal and are easily made into diffusely dispersed suspensions. Carbon nanotube coatings or filled polymers can offer a modern take on the old-fashioned wire networks that have been used for so long--but with "wire" diameters 1000 times thinner and with the wires randomly distributed rather than forming a grid. And graphene, as it becomes easier to produce, too will find its way into applications that take advantage of its electrical conductivity, and perhaps applications using graphene as an ESD material will be among those.
Conductive polymers like PEDOT:PSS have been unable to achieve conductivity comparable to that of metals, limiting their utility for the highest-value applications like ITO substitutes. But they appear to be well-suited to less conductive applications. These materials are not inherently expensive but have not come down in price as rapidly as hoped. Still, they are flexible and often transparent, especially in very thin layers as required for the high resistivity of ESD applications, and offer the likelihood of low cost within the next several years.
Source: New Materials Line Up for Anti-Static Applications
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