Hi Joe, 3 pieces of AP 8525 - DuPont. Bondply - polyimide adhesive 35 micron, apical- 12 micron, polyimide adhesive- 15 micron. Cracks start in the 15 micron polyimide adhesive- no total failures yet - drill size 10 mils - aspect ratio - nothing special. About 200 vias per part. Thermal - +200c- -60C as fast as they can cycle the chamber. This is one end of the flex - the other end is a rigid flex - same flex build then added 2 layers of polyimide rigid either side - this end shows none of the cracking so I assume somehow the GI is stopping the polyimide adhesive from expanding as much. Regards Steve -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad Sent: December-22-09 11:58 AM To: [log in to unmask] Subject: Re: [TN] Via fill on flex Hi Steve Are all vias impacted or just some? If the latter, any common characteristics? (i.e aspect ratio, stack up, location in stack, etc.) For shared edification, what are the materials in the set and what are the cycling conditions and requirements? (at least so we can all get a sense of what kind of unreasonable requirements might be out there looming on the horizon) Season's best, Joe In a message dated 12/22/2009 8:26:57 A.M. Pacific Standard Time, [log in to unmask] writes: Hi All, We have a 6 layer flex that my customer has to thermal cycle at temperatures beyond the rated Tg's of the material- the end use environment is about as bad as it gets. After repeated thermal cycles we start to see cracks develop in the glue layer used to bond the adhesiveless layers together. Will some kind of via fill help this issue? Thanks in advance. Regards Steve Kelly Steve Kelly (PLEASE NOTE NEW E-MAIL ADDRESS) (416) 750-8433 (work) (416) 750-0016 (fax) (416) 577-8433 (cell) --------------------------------------------------- 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 -----------------------------------------------------