Electrostatic discharge (ESD) control is mandated in all manufacturing processes due to its adverse effects on electronic components and products. To meet the growing industry needs, there are now many products and solutions that keep ESD in check.
By Baishakhi Dutta
The demand for products that offer protection against ESD continues to grow across the globe. And with computing and electronics becoming pervasive, the size of the ESD products market is bound to grow. The increased use of nanomaterials will also give an impetus to the ESD products market. With electronics manufacturing on the rise in India, the domestic ESD products market is already experiencing an upsurge. To keep pace with international trends, ESD products in India are also going through a phase of major upgradation.
A few application areas of clean rooms
Clean rooms are typically used in manufacturing, packaging and research facilities associated with the following industries.
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Semiconductors: The semiconductor industry drives the state-of-art clean room design, and accounts for a major portion of all clean room operations.
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Aerospace: Manufacturing and assembling of aerospace electronics systems, missiles and satellites require a huge amount of clean room products. In this field, large clean room spaces with utmost cleanliness are of critical importance.
Choosing the right product
One should choose ESD products depending on the class of the clean room, which could be Class 1, Class 10, Class 100, Class 1000 and Class 100,000, depending upon factors like air changes per hour, which is ascertained by the ceiling filter coverage of the room, and the percentage of high efficiency particulate air (HEPA) present in the room, for which a HEPA filter is required. This is a type of filter that can trap a large amount of very small particles. While a huge array of ESD products is available, these should be selected after proper consultation with experts. For instance, while buying ionisers, one should look at the reputation of the brand, the ozone produced in the product and how long it can maintain the balance of ions.
Controlling contaminants
Contaminants can be controlled primarily through airflow design. Major sources of particulate contamination include construction finishes, garment materials, equipment, and personnel. Major control precautions include:
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Materials and equipment must be cleaned before entering the clean room.
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The materials used on the floors, walls, ceiling tiles, lighting fixtures, doors and windows must be carefully selected to meet clean room standards.
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The garments that people wear along with their ESD safe outfits should minimise the release of particles into the space. Clean room compliant wearables include smocks, coveralls, gloves as well as head and shoe covers.
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Room entrances such as air locks and pass-through chambers are used to maintain pressure differentials and reduce contaminants.
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Each individual’s ESD-safe compliance can be ensured by using an air shower before entering the clean room.
International standards
A clean room manufacturing system has to comply with a set of standards, including those set for specific products or procedures like packaging requirements and grounding. The typical standards in this group are ANSI/ESD S6.1 Grounding and ANSI/ESD S541–Packaging Materials for ESD sensitive items. There are also specific standards for test methods that focus on ESD in the electronics manufacturing environment. These include standards such as ANSI/ESDA-JEDEC JS-0012010—Device Testing, Human Body Model; and ANSI/ESD STM7.1: Floor Materials— Resistive Characterisation of Materials, to cite a few.
What’s new in the market
ESD products are used for protecting electronic circuit boards and other electronic products from electrostatic discharges. From the array of products available in the market, let us explore what’s new in anti-static flooring and table-top systems, ESD test and measurement devices, static elimination products, and ESD-safe adhesives and tapes.
Hazardous impact of ESD
Unchecked ESD can be very harmful for electronic components. It can destroy the chip completely or result in a defect that may impact the functionalities of the product in the long run.
Most semiconductor devices today are treated as static-sensitive devices (SSD). To prevent damage, they must be handled in anti-static areas called EPAs. What makes these areas static-proof is the variety of precautions taken to ensure that the static is dissipated and that the SSD does not experience any static discharges. Benches with anti-static flooring, dissipative surfaces, wrist straps for operators and many more items add up to creating an anti-static ecosystem.
ESD test and measurement instruments: Companies continue to develop and create new ESD measurement technologies as per the needs of the industry. There are currently new types of wrist strap-cum-dual-footwear testers in the market, which are used for testing the quality of the ESD wrist strap and footwear. These instruments, independently and simultaneously, test the right and left feet as well as the wrist strap, thereby reducing the testing time by half. They offer the operator a visual and audible ‘pass’ or ‘fail’ verdict for both feet and the wrist strap, before the wearer enters the clean room or the EPAs (electrostatic protected areas).
ESD safe work surfaces: It is necessary to make the work surfaces and other work areas anti-static in an electronics manufacturing or assembling facility. Anti-static mats are made of polyethylene film, and are used to trap impurities in areas that require dust and dirt levels to be controlled. The surface of these mats pulls dirt and dust from shoe soles before these can contaminate a clean room.
Static elimination products: ESD ionisers neutralise a static charge by balancing the ions between the molecules in the gases of the surrounding air. These are typically used to control static on isolated conductors that cannot be grounded and on insulated objects (like standard plastics).
ESD-safe adhesives and tapes: ESD-safe adhesives and tapes are used in ESD-sensitive environments for sealing anti-static bags; to pack electronic components, medical instruments and precision mechanical equipment; and for splicing films.
