ESDA Threshold Vol 29 No. 4 Dissipative tools which are designed to touch products
Q1) Hand tools- if the tools are not ESD rated is it acceptable to:
A. Instruct the operator to neutralize the tools with ESD spray daily i.e., Staticide and to keep the tools at a minimum of 12 inches away from the work at hand.
B. Supply the station with an Ionizer?
A1) Both strategies may be acceptable under certain conditions but may not be optimal. If the tools never touch sensitive product directly and are kept 12 inches away then that may be all you need to do. Furthermore the staticide will become compromised quickly after only a few uses since it rubs off easily. Also keep in mind that tools which are designed to touch product (e.g., tweezers) should have dissipative tips (not the handles) if possible or care should be taken to control voltage and that is where the ionizer would come in.
Q2) If we tie a common point ground to the electrical ground at a workstation do we need to have a 1 megohm resistor installed or can direct be acceptable? What about racks through a 1 megohm resistor or direct?
A2) The 1 megohm resistor is NOT necessary in either case. The only place this resistor is required is for wrist straps where the purpose is to limit current that might flow through a person. The resistor is NOT an ESD-protective element.
Q3) Is the following statement true or necessary in an ESD control program?
“To probe test points of an ESD device or assembly, touch the probes to ground first”.
A3) The important thing is that the probes and the device are at the same potential or as close as possible. If the device is sitting on a grounded work- surface and has a path to ground, this is achievable. Of course if you are making a measurement the voltage on the probes will be determined by the instrument.
Q4) Can power supplies, oscilloscopes etc., be used on the ESD workstation?
A4) Yes. The only minor complication is that grounded equipment on a work surface may interfere with the verification that the surface is properly grounded. It is therefore suggested, if practical, to verify the ESD ground path with the other equipment removed from the surface.