ESD Systems - Questions And Answers

We are setting up three circuit card assembly test benches, each with a 115VAC, 20A strip, grounded ESD mats (tied to facility ground), and a wrist strap w/1megohm. Each test station consists of acomputer; a 14" monitor; an oscilloscope; a function generator; a counter;three(3) low-voltage (12V & under) power supplies; and a VME chassis withan extender card for mounting the UUT (Unit Under Test). Our concern isthe monitor & computer, and the static electricity or radiated transientsfrom switching that may affect the UUT. What are your recommendations? - George Lawhon

First you want to make sure you have all unnecessary charge generators removed from your ESD Safe work area. The ones you need at the ESD Safe work area then need to be controlled. The computer would not really pose an ESD risk as long as the chassis is grounded if the case is metal. If the case is plastic, then spraying it and wiping it down with our ReZtore™ Antistatic would add a topical layer of dissipative and antistatic coating to minimize charge build up. The same treatment can be applied to the monitor.In both cases, the ANSI/ESD-S20.20-1999 standard document says, “all process essential insulators that have electrostatic fields that exceed 2,000 volts should be kept at a minimum distance of 12 inches from ESDS items. 2,000 volts is a measure of the electrostatic field at the point of measurement and is not necessarily directly related to the electrical potential of the item.” This would apply to your test equipment and computer/monitor. Another way to control these items is with Ionization.

Related Categories:

If you have found this Q/A useful, please rate it based on its helpfulness.