Induction charging risk assessment: Charged board alike discharges to metal and human body

• Published in: Journal of electrostatics Vol. 67; no. 2; pp. 263 - 266
• Main Authors: Fast, Lars, Paasi, Jaakko, Smallwood, Jeremy, Karlson, Ingvar
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-05-2009
• Subjects: Electrostatic discharge; ESD sensitive devices; Risk assessment; Risk assessment; ESD sensitive devices; Electrostatic discharge
• ISSN: 0304-3886; 1873-5738
• DOI: 10.1016/j.elstat.2009.01.024

Charge can easily be induced on electronics or on other conducting parts if they are exposed to external electrical fields. In production facilities where sensitive electronics are handled, strong electrostatic fields should be avoided due to the risk of causing electrostatic discharges (ESDs) that could damage components. In electronics manufacturing this is usually achieved by grounding all conductors and removing all insulators from an ESD Protected Area (EPA) in the facility. However, it is not always possible to remove all insulators from the EPA as they are sometimes an essential part of the production processes. In this case, a method of risk assessment is necessary to evaluate safe operation. We have studied induction charging of a dummy PWB (Printed Wiring Board) through a grounded MOSFET transistor, by grounding it directly to metal or through the human body, when the PWB is exposed to a static electric field. The experimental setup can easily be turned into an induction charging probe by changing the MOSFET transistor to a low leakage current, high voltage capacitor of suitable size and measuring the voltage over this capacitor.