"We know what we know", followed by: "we know what we think we know", then there is: "we know what we don't know" and finaly: "we don't know what we don't know". Yuk, Ahne. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of valerie St. Cyr Sent: Tuesday, 03 October, 2006 7:46 To: [log in to unmask] Subject: Re: [TN] #3 laminate Qualification All, There are materials whose properties' data sheets have the values that would indicate high thermal stability, and so one might conclude they could pass a lead free reflow or reflows. But it is not so simple. As the laminators load up on fillers to restrain the Z-axis CTE to mitigate against the higher temperature at reflow, the interlaminar strength can be compromised. We are seeing an x-y sheer phenomena. The delamination is not prepreg to copper, or adhesive failure, it can be within a core, or prepreg to glass - a cohesive failure. Also, regardless of the above, your particular design might survive a lead free reflow process while another design on the same material fabricated by the same supplier will not. Some of these materials have design dependencies only now being understood. OK, if that isn't problematic enough, these materials aren't drop-in replacements in the fabricator's processes despite any claims to the contrary from the laminators. So, for the same design on the same material if you switch fabricators you could then experience delamination or massive hole wall pullaway (which we haven't seen in a very long time). What else ? Oh yeah, for non-phenolic systems better prebake before assembly ... What else ? Oh yeah, some (not all, but some) are still being tweaked and what worked last month may not work next month. We are not done learning yet... all the answers aren't in. In fact, some of the experiments have even been thought of yet. my 42 cents. Valerie Werner Engelmaier <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 10/02/2006 06:29 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to [log in to unmask] To [log in to unmask] cc Subject Re: [TN] #3 laminate Qualification Hi Dave, Well, I spoke too soon. I did come across numbers similar to these: Tg=210 C, Td=365 C, just not in this combination. There are: N4000-13 200°C 365°C 3.5% STII=247 TU-832 210°C 340°C 2.5% STII=250 IS620 ~205°C 353°C 2.8% STII=251 Werner --------------------------------------------------- Technet Mail List provided as a 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/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 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/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 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------