Reduction of electrostatic ESD

Electrostatic Discharge (ESD)

What is perceived as unpleasant in everyday life, but is not dangerous, often causes damage in the millions in industry: especially in the manufacture of electronic components, where, due to the sensitivity of the semiconductors, even the slightest electrostatic discharge can cause major damage. These components can already be damaged by discharges from a voltage (potential) of less than 100 V. This sounds relatively high: however, it should be borne in mind that humans do not perceive electrostatic discharges below 2000 V.


Influence of humidity on electrostatic discharge (ESD)

Influence of electrostatics in the processing of plastics and other materials

Electrical charging is also a disruptive factor in the processing of plastics. Foils and plastics that are electrically charged through friction attract electrostatically chargeable substances. Dust and particles thus find their way to the machine and product more quickly and settle on them as a film of dirt. In addition to film production and processing, there are a large number of processes with a similar topic. Due to the friction and movement of materials, machine parts can become charged with a voltage that is also dangerous for people. This can result in personal injury or even fires due to self-ignition.

The electrical charge is greater, the lower the room air humidity. Moist air enriches ions, making them heavier and more sluggish in the electrical environment. At an air humidity of >50%, the conductivity of the air on the material surfaces is increased so that the electrical charges can be dissipated. During this process, a wafer-thin film of moisture forms on the materials. This makes the surface conductive to the extent that unwanted charges are discharged.

Use of mixed-bed deionization systems

Some suppliers of air humidification systems offer a flat rate for mixed-bed deionization systems specifically for different branches of industry. However, the requirement about sense or senselessness should be checked here! Deionization in no way replaces hygiene, but is only an additional system for e.g. B. to see dissolved salts.

A reverse osmosis filters in the spectrum < 0.001 µm and is sufficient as a hyper filter system for almost all areas of the most diverse clean room classes. A need for deionization systems should therefore be assessed by comparing the retention rate of the air filter systems used in the affected rooms to be humidified.

Deionization is a chemical process that uses specially manufactured ion exchange resins that use hydrogen and hydroxide ions to exchange dissolved minerals and then recombine into water. Since most non-particulate water contaminants are dissolved salts, deionization produces high purity water that is generally similar to distilled water.

Deionized water is very aggressive to both metals and plastics. The normal use of deionized water is in closed systems that have dedicated equipment and resistant housings or in laboratory use.

In the field of air humidification systems, we are rather skeptical about the use of such an aggressive humidification medium. If reverse osmosis is used, hyperfiltration with a pore size of <1Nm is used. Here, the operator should weigh up his own requirements in detail as to whether the use of deionization is actually necessary.