Interesting Mel. What is the process for calculating the grounding resistor, based on equipment operating voltage? Dave Fish Mel Parrish wrote: > Lee and Ashok, > While it is sometimes common practice to earth ground an ESD safe bench, > resistance is required to reduce hazardous shock exposure of operators > should they come in contact with an available voltage source at the bench. > Additionally, the resistance level is as specified considering the common > potential resource of 115VAC (solderin irons, lights, etc) and should there > be higher potentials available, the resistance value will need to be > reassessed. Increase in available voltage potentials requires equivalent > increase in resistance value to provide operator protection from a path to > ground. A 1M ohm resistance is inadequate if there is a 300 V resource at > the bench. While assessing the aspects of a correct ESD bench it is > important to keep in mind the possibility of parallel ground paths which > reduce the effective resistence. MIL-HDBK-263 contains detailed information > concerning these topics. > It is also important to provide a decay characteristic for applied voltage > potentials to bleed off without creating as great a potential for damage to > sensitive components that could be in the path of a potential surge in it's > effort to seek ground potential. > EIA 625 as an ESD standard applies well to component environments but other > standards such as the previous MIL-STD-1686 (with support of MIL-HDBK-263) > and ESDA S20.20 may provide additional information that is useful for > product assembly operations. IPC-A-610C has updated ESD information as well > as graphics for ESD bench attachment. > As for the attachments the major requirement is that it be rugged enough to > withstand production environments and be monitored or tested to prevent > processing equipment in a potential ESD hazard environments. Again the Mil > Specs recommend at least a half watt resistor and I would add a protective > covering to support the lead attachments (shrink sleeving)as well. A plus > would be sleeving that allows visual inspection. > Contact me if I can be of any assistance. > Mel Parrish > 201 Cedar Road > Mullica Hill, NJ 08062 > [log in to unmask] > 856 223 5828 > > ----- Original Message ----- > From: Lee Whiteman <[log in to unmask]> > To: <[log in to unmask]> > Sent: Tuesday, May 23, 2000 5:36 PM > Subject: Re: [TN] Question on EIA-625 : Technical specs of Grounding > resistor > > > >From my experience, one does not require a grounding resistor on table > mats > > / floor mats. In fact, I've connected them directly into earth ground. > > > > According to EIA-625, Figure 1 (page 8), the resistors for the static > > dissipative work surfaces (R2) and the ESD protective floor mats (R3) are > > optional. If you are using R2 and R3, the values should be specified by > the > > ESD equipment manufacturer. I don't think there are any special > requirements > > (wattage, material of construction, etc.) for this resistor. > > > > Lee Whiteman > > Senior Manufacturing Engineer > > ACI / EMPF > > Telephone: (610) 362-1200; Ext. 208 > > FAX: (610) 362-1290 > > E-Mail: [log in to unmask] > > > > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Ashok Dhawan > > Sent: Tuesday, May 23, 2000 6:51 PM > > To: [log in to unmask] > > Subject: [TN] Question on EIA-625 : Technical specs of Grounding > resistor > > > > << File: adhawan.vcf >> For grounding Table Mats/ Floor Mats and > > workstations, does grounding > > resistor need special > > characteristics e.g. Wattage, material of > > construction, etc. > > We intend to use 1M Ohms resistor. EIA-625 does refer > > to EOS/ESD-S6.1 standard ( > > paragraph 7) for grounding details, if anyone has > > that details on that. > > > > Thanks in advance for advice. > > > > Ashok > > > > -- > > > > Ashok Dhawan P.Eng > > Engineering > > C-Mac Electronic Systems Inc. > > 1455 Mountain Avenue > > Winnipeg, Manitoba R2X 2Y9 > > Canada > > Phone: (204) 631-7208 > > Fax: (204) 631-7294 > > E-mail: [log in to unmask] > > www.cmac.ca > > > > ############################################################## > > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > > ############################################################## > > To subscribe/unsubscribe, send a message to [log in to unmask] with > following text in > > the body: > > To subscribe: SUBSCRIBE TECHNET <your full name> > > To unsubscribe: SIGNOFF TECHNET > > ############################################################## > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > > information. > > If you need assistance - contact Keach Sasamori at [log in to unmask] or > > 847-509-9700 ext.5315 > > ############################################################## > > > > ############################################################## > > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > > ############################################################## > > To subscribe/unsubscribe, send a message to [log in to unmask] with > following text in > > the body: > > To subscribe: SUBSCRIBE TECHNET <your full name> > > To unsubscribe: SIGNOFF TECHNET > > ############################################################## > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > > information. > > If you need assistance - contact Keach Sasamori at [log in to unmask] or > > 847-509-9700 ext.5315 > > ############################################################## > > > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. 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