Ionization must be used when:
A process required insulator can be charged to more than 125 volts AND is within 1 inch (2.5cm) of a ESD sensitive item (TR20.20-2016 ESDA)
or
A process required insulator can be charged to more than 2000 volts AND is within 12 inch (30cm) of a ESD sensitive item (TR20.20-2016 ESDA)
or
An Isolated conductor comes into contact with an ESD susceptible item that cannot be grounded or equipotentially bonded. The process must ensure that the difference in potential between the conductor and the contact of the ESDS item is less than 35 volts. (ANSI/ESD S20.20-2014 – Section 8.3.2 Isolated Conductors ESDA)
Process Required Insulators and Isolated Conductors: A process required insulator is an insulator that can not be removed from (or replaced) the ESD Protected Area. Common process required insulators used for manufacturing electronics include flex cables, product enclosures, and test fixtures. An isolated conductor is a conductor that comes into contact with an ESD susceptible item cannot be grounded or equipotentially bonded. Some examples of isolated conductors would in include components, PCBs in test/assembly fixtures, or hand tools.
Neutralization: Ionizers are used to neutralization of process required insulators or isolated conductors. This does occur naturally by combining with free positive and negative charged ions in the local environment. However, the process is too slow to protect ESD susceptible devices. Ionizers flood the coverage area with positive and negative charge ions to neutralize existing charges that may be present and prevent charges from being created.
Contact Desco for more information about when you need to ionize or how to choose the right ionizer for your application.