Franklin offers good advice; many circuit boards should be baked prior to processing. Immersion silver boards are prebaked on a regular basis throughout the industry, and IF they are packaged and stored properly per IPC-4553 (read it, please) they can easily be baked for up to 24 hours @ 105 deg. C, which I know is more than enough to remove more than 85% of the fully saturated moisture content of a printed wiring board that is 36" wide by 24" high and consists of 48 layers with 18 miles of embedded copper, .50" thick, 180 Tg with no detectable drop in the solder DPU or reliability. On the other hand, Guy is correct in that reckless HANDLING and STORAGE and baking at improper temperatures can quickly render the boards unsolderable. And as for immersion tin, well, that is really not a practical circuit board finish... lets not go there today. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey Sent: Tuesday, October 23, 2007 2:51 PM To: [log in to unmask] Subject: Re: [TN] Delamination of lead free PCBs It should be noted that immersion tin and immersion silver may not respond well to baking. Reckless methods can render the boards unsolderable. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell Sent: Tuesday, October 23, 2007 1:39 PM To: [log in to unmask] Subject: Re: [TN] Delamination of lead free PCBs Joel, Baking was indeed required for leaded PCBs, the nature of most laminates is to suck up moisture regardless of the Tg or final finish. Also, depending upon the laminate type, baking may be necessary immediately upon receipt from the board supplier. I always caution assemblers to bake boards regardless, it just makes good sense. Franklin D Asbell -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Alexander Sent: Tuesday, October 23, 2007 11:23 AM To: [log in to unmask] Subject: [TN] Delamination of lead free PCBs Has anyone experienced an increase of delamination when processing in a lead free environment. Typically 4 to 6 layer pcbs during SMT reflow. We are using the high temp laminate suggested for our process. When we contacted the supplier and they indicated that any PCBs that are over six months old should be baked prior to processing. This was never required with leaded PCBs. Is anyone seeing the same condition and similar feedback from your PCB suppliers Joel Alexander Quality Assurance Manager TT APSCO, INC. --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------