Hi Bev, There was a previous requirement in IPC specs J-STD-001B and IPC-A-610B which stated a component standoff height (dimension G) of 0.2 mm. Although this was stated as a requirement for cleaning, that actually was a side benefit to the original primary purpose of improved survivability of the solder connections for non compliant lead components. It was based upon a study that supported the improved performance with that dimension rather than those closer to the surface of the board. Happy reading! Mel Parrish Director, Training Materials Resources Soldering Technology International 102 Tribble Drive Madison, AL 35758 256 705 5530 256 705 5538 Fax [log in to unmask] www.solderingtech.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian Sent: Thursday, March 20, 2003 1:31 PM To: [log in to unmask] Subject: Re: [TN] SMT Component Standoffs Ha! I just got a copy and have read up to page 33, right before Appendix A. Now I know I will be reading tonight. :} Bev -------------------------- Sent from my BlackBerry Wireless Handheld (www.BlackBerry.net) -----Original Message----- From: Guy Ramsey <[log in to unmask]> To: 'TechNet E-Mail Forum.' <[log in to unmask]>; Bev Christian <[log in to unmask]> Sent: Thu Mar 20 14:28:19 2003 Subject: RE: [TN] SMT Component Standoffs Yes, now you are getting picky ;~) Do you have a copy of IPC-D-279? Section 3.5 Solder Joint Reliability, specifically 3.5.1.3 Solder Joint Height seems to be the variable you are asking about. It is part of the prediction equations A-3 and A-4 in the Design Guidelines. I have not seen these translated into DFR rules. I think the other variables you mentioned would exert too much of an influence to make any hard and fast rules. Flexible rules . . . Sounds like Philadelphia traffic laws. Werner? > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian > Sent: Thursday, March 20, 2003 1:31 PM > To: [log in to unmask] > Subject: Re: [TN] SMT Component Standoffs > > > Thanks, Guy, BUT this has to do with cleaning rather than > mechanical reliability. > Bev > -------------------------- > Sent from my BlackBerry Wireless Handheld (www.BlackBerry.net) > > > -----Original Message----- > From: Guy Ramsey <[log in to unmask]> > To: 'TechNet E-Mail Forum.' <[log in to unmask]>; Bev Christian > <[log in to unmask]> > Sent: Thu Mar 20 13:17:55 2003 > Subject: RE: [TN] SMT Component Standoffs > > > There is help in IPC-SM-782A section 3.6.1.7 Component Stand > Off Height for Cleaning and the associated table 3-7. The > stand off recommendation varies with the component size. For > example small component < 3mm x 3mm stand off > 0.05 mm. A > large component 50mm x 50 mm stand off > 0.5 mm. > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian > > Sent: Thursday, March 20, 2003 12:56 PM > > To: [log in to unmask] > > Subject: [TN] SMT Component Standoffs > > > > > > TechNetters, > > When I was at a former employer there was a minimum stand off > > in the company specs. I have forgotten what that was. Now I > > know that it can/should be different based on the solder, use > > environment, pad sizes and lead/termination materials, but I > > was wondering if anyone would be willing to share what they > > have on the subject. I am particularly interested in land > > grid array devices, if I may be so bold as to be picky. :) > > Thanks in advance. > > Bev Christian > > Research in Motion > > > > --------------------------------------------------- > > Technet Mail List provided as a free 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/html/forum.htm for > > additional information, or 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 1.8e > 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/html/forum.htm for additional > information, or 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 1.8e 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/html/forum.htm for additional information, or 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 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------