Mel, What's your interpretation of the 5 thermal cycles - do they include the thermal cycling used to fabricate the PCB in the first place? And what temperatures are we talking about? Does, say, a bake cycle at 90 degrees count, or are we talking reflow temperatures? Just curious. Peter Mel Parrish <[log in to unmask]> 19/12/2002 11:16 PM Sent by: TechNet <[log in to unmask]> Please respond to "TechNet E-Mail Forum."; Please respond to Mel Parrish To: [log in to unmask] cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group) Subject: Re: [TN] PCB Repair Criteria Much of the ability to survive rework or thermal excursions is dependent upon the fabrication materials. The board qualification criteria under the 55110 was designed around 5 thermal cycles, which if you add them up, gives you one rework process if it requires extraction and site preparation. After that all bets are off. The qualification other than 55110 is less robust so you can see what you might be up against. Good Luck, Mel -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Victor Hernandez Sent: Thursday, December 19, 2002 8:34 AM To: [log in to unmask] Subject: Re: [TN] PCB Repair Criteria The repair site is a Power FET on a .062 PCB with 4 layers. This is the Vcore plane. Perhaps 1oz. victor, -----Original Message----- From: Charles Caswell [mailto:[log in to unmask]] Sent: Thursday, December 19, 2002 8:30 AM To: [log in to unmask] Subject: Re: [TN] PCB Repair Criteria This is a difficult question to answer. The simple answer is none.There are too many factors involved. Lead to hole ratio, copper weight, skill of operator and equipment used are all variables to consider. I have removed and replaced a 172 pin PGA 15 times in a 15 layer board with no apparent damage. Although I'm sure there was some degradation to the life expectancy of the board. This board was later used as part of the flight qualification, -40 to +85 degC severe vibe etc. and passed. I will be watching for other replies to this one. Charles Caswell -----Original Message----- From: Victor Hernandez [mailto:[log in to unmask]] Sent: Thursday, December 19, 2002 7:55 AM To: [log in to unmask] Subject: [TN] PCB Repair Criteria > Fellow TechNetters, > > Can some one assist me with this question. How man times can a PTH > component be safely removed before damage to the inner connections on the barrel occurs. > Victor G. Hernandez > --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------