Hi Steve, I am not familiar with that device, but is the heatsink lifting at the edge? If not, it looks like the encapsulant they use has a bevel around the corners when they mold. Just a guess. Maybe Altera would send you a picture of a part. Kerry McMullen Principal New Product Mfg. Engineer LTX Corporation 50 Rosemont Road Westwood, MA 02090-2306 (T) 781-467-5468 Stephen Gregory <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 07/27/2005 12:35 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 [TN] Strange Looking BGA Heatsink Gap... Hi Everyone! We just finished building 8-assemblies that used a 780-ball Altera Stratix BGA on them. These BGA's have a pretty decent sized copper heatsink in the top. Everything went pretty good. But then I noticed something with the BGA heatsink after we got them all built. In the corners, there seems to be some sort of gap beneath the heatsink and the top of the part that I didn't notice before. Go to: http://www.stevezeva.homestead.com then click on Picture Page 2, then look for "Heatsink Gap". All the BGA's show this in all 4-corners. I don't have any more of these BGA's around that haven't been through reflow, so I can't do a before and after reflow comparison. The Altera package drawing doesn't show this gap either. I'm thinking (hoping) that the parts are made like this, to somehow keep the whole part from warping during reflow because of a CTE mismatch between the substrate and the heatsink...it just looks strange though. Anybody else out there familiar with these devices that can tell me this is normal? (Please tell me this is normal!!) Kind regards, -Steve Gregory- Senior Process Engineer LaBarge Incorporated Tulsa, Oklahoma (918) 459-2285 (918) 459-2350 FAX __________________________________________________________________ This message may contain information that is privileged and confidential to LaBarge, Inc. It is for use only by the individual or entity named above. If you are not the intended recipient, you may not copy, use or deliver this message to anyone. In such event, you should destroy the message and kindly notify the sender by reply e-mail. --------------------------------------------------- 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 -----------------------------------------------------