Karen, There is no discharge event when you touch the charged plastic. Where would a current flow along the plastic surface or through the plastic. Glass is the same idea. These are insulators. Bob Kondner -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen Sent: Thursday, May 14, 2009 4:13 PM To: [log in to unmask] Subject: Re: [TN] Bare PCB Packaging Requirements An electrical field is a voltage (potential) gradient, and may be given is volts/meter or newtons/coulomb. If I rub a piece of plastic with wool so that it is charged and has an electrical potential different from ground, then, while electrically grounded, will I feel a shock if I touch the plastic? Probably, and that's current. If a chip is carefully placed on a uniformly charged plastic surface with a uniform electrical potential, it will likely experience no current. If a bird perches on a single, live power cable, it will not be injured. This will not be the case if a squirrel simultaneously touches the hot cable and the return. Likewise, if one of the connectors on an IC package is grounded, possibly by somebody,s hand, and another connector contacts a charged surface, it is possible for current to be passed through the IC. A piece of plastic may not have a uniform electrical potential along its surface, and hence an electrical field. For more information: http://en.wikipedia.org/wiki/Electrostatic_discharge Karen Tellefsen - Electrical Testing [log in to unmask] 908-791-3069 -----Original Message----- Inge, Is Electric Field really the issue or is it more of a case of induced currents? If I rub a piece of plastic with wool so It has a very high field, and if I then set an IC on that plastic, will any current flow anywhere? If not then I do not see how the IC can be damaged. If I take a 1.5 volt battery and connect it to power and signal pins will current flow? I think so and the part will probably be destroyed. So is it field or induced current levels? Thanks, Bob Kondner ----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Thursday, May 14, 2009 2:49 PM To: [log in to unmask] Subject: Re: [TN] Bare PCB Packaging Requirements Electrostatic fields can be induced in high dielectrics and once there, may be hard to get rid of. As little as 50 VDC can be a problem for IC chips without enough I/O diode protections. We have had some issues which might have been caused by such surface charges, but we could never prove it. To be sure , we demand ESD safe bags. Additional cost negligible. Inge --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 -----------------------------------------------------