Do ordinary fans pose a risk to static sensitive products?
Customer asks: I work in a manufacturing facility and the production department says it is very hot near the heat welder. Currently we mainly use huge fans mounted horizontally above the heat welders and air conditioning units that run throughout the shop. Does this pose a risk to static sensitive products?
Reply: Ion fans are recommended for use in static protection areas. However, there are some concerns, including:
l Airflow friction charging
l Fan components are highly charged insulators (eg: housing or blades)
l If an ionizer is used, the normal fan airflow will interfere with the ionization airflow
Gases such as those from an air gun, fan or heat gun will not tribocharge insulators or conductors. Tribocharging can occur if rapid air movement causes parts or dust particles to rub against each other. A grounded conductive surface will tribocharge an insulating surface. Insulating surfaces can charge ungrounded conductors, which is the greatest ESD hazard. "
If fan assemblies are insulated, they should be kept 30CM away from static sensitive items. Per ANSI/ESD S20.20 Paragraph 6.2.3.2, Protected Area Guidelines "All process-essential insulators with electrostatic fields in excess of 2,000 volts shall be kept at least 30CM from ESDS items."
With normal fans running, the static eliminator performance of all ionizers used should be checked for any performance degradation.