Rex, this is the BEST answer I've seen for a torque spec . . . problem is, I'm usually the customer. However Walt, there are way too many elements to consider for canned specs, hence you will have a hard time finding one especially for hardware under 1/4". Bottom line - all lock washers must be fully collapsed & the stack-up per IPC-A-610. If KEP nuts or SEMS screws are being used then the mfr will have a recommendation. If threadlocker or locking inserts are used then snug is good. If you are using electric or pneumatic drivers, set to lowest possible setting that will seat the hardware without tightening then go back & torque - don't confuse driving force with torque. Also, don't confuse interference force with torque before proper seating is achieved. In other words, the torque settings are pretty much product specific. And as mentioned, if you have a chance to evaluate a field return or a unit that has been thru environmental qualification you can verify your spec & adjust (and recall if necessary) as required. Good luck, Loa -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood Sent: Thursday, October 08, 2009 6:55 AM To: [log in to unmask] Subject: Re: [TN] torque In cases like this, where the customer often has a feel for what they want, we provide them with an indicating torque driver and ask them to do it up to the tightness they feel appropriate. We then set the spec to that torque. Regards Rex Technical Manager Hansatech EMS provides value manufacturing through engineering and quality Hansatech EMS Limited Benson Road Nuffield Industrial Estate Poole Dorset BH17 0RY United Kingdom Tel: +44 (0)1202 338200 Fax: +44 (0)1202 338202 DDI: +44 (0)1202 338222 [log in to unmask] www.HansatechEMS.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Walt Manchin Sent: 08 October 2009 14:29 To: [log in to unmask] Subject: [TN] torque Hello All, I have been working with customer that wants to attach daughter board to mother board using standoffs and #6 screw. We found specifications for torque on certain type of screws, but what is your experience on the torque required to attach PCB's before causing damage to the BOARDS AND/OR MATERIALS? Thanks in advance. Walter Manchin Prototron Circuits Mid Atlantic 610-499-4964 - (office) 610-299-8969 - (cell) mailto:[log in to unmask] www.prototron.com <http://www.prototron.com/> Prototron --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------