Lots of info in ESD on the internet, for example, http://www.esda.org is not a bad place to start. As suggested by others, it's easy to build up charges over 30,000 volts on plastics and damage to ESD sensitive components can occur at a fraction of this. There are also a few ways to inflict damage by ESD: discharge to the device, discharge from the device and field induced charges that can then lead to an dangerous discharge. Most component spec. sheets I've seen will specify different maximum voltages for these ESD 'events' types typically referred to as Human Body Model (HBM), Charged Device Model (CDM) and Machine Model (MM). If no specs exist, I'd be very, very careful about relying on a certain charge not being able to jump a certain distance not only because environment conditions influence this so much but because you could still be damaging your parts without a 'zap' taking place, or inducing a charge that leads to a 'zap' down the line somewhere. Of course, keeping in mind that by the time you see or hear a zap you've got thousands of volts.... Richard van Beveren Robert Bosch (Australia) Pty Ltd -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Brooks,Bill Sent: Saturday, 7 May 2005 1:07 AM To: [log in to unmask] Subject: [TN] FW: Static and break over voltage spacing standards? I hope that someone on the forum may have a comment or two about this subject... and can help John. - Bill -----Original Message----- From: John Smith [mailto:[log in to unmask]] Sent: Thursday, May 05, 2005 7:21 AM To: 'Bill Brooks' Subject: RE: Web site question Thank you for your response Bill, I am trying find out at what voltage and at what distance I need to be concerned about a static discharge from a plastic surface. I have a silicon wafer processing tool and there is concern about static discharge from the exterior plastic panels. I want to be able to determine, the voltage vs.. distance safe point, i.e. (at 500v of charge an arc will not jump at a greater distance than .5") I understand that the type of material, the humidity and other factors make a difference, but there must be some test data some where that points to some generalities. Thanks again for your time bill John -----Original Message----- From: Bill Brooks [mailto:[log in to unmask]] Sent: Wednesday, May 04, 2005 11:03 PM To: 'John Smith' Subject: RE: Web site question http://sprott.physics.wisc.edu/demobook/chapter4.htm see table 4.2 The issue with predicting electrical arcing is in defining the environmental conditions that contribute to the 'break over' voltage. The presence of dry ionizing air, or ionic contamination on a surface can greatly increase the distance at which break over will occur. Once the arc is established, it ionizes an electrical path which is much lower in resistance that the initial break over voltage required to jump across the electrodes and the two points of potential can be moved much farther apart and they will still conduct... What are you trying to do? Bill Brooks -----Original Message----- From: John Smith [mailto:[log in to unmask]] Sent: Wednesday, May 04, 2005 2:09 PM To: [log in to unmask] Subject: Web site question Is there a guideline that references how far a static charge will jump? i.e. a 500v charge could be expected to jump or ark how far? --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------