My experience is something what you mentioned ,that is, stencil opening (solder volume) is the main "issue" which caused the process problem. With multi-row/column of I/O, the package seems to be similar to LGA BUT with a much larger heatsink at the center of the package. The I/O will encounter open issue (related to heatsink pad opening design) or short issue (related to I/O pads opening design). Another way is to "bump" the I/O (not the heatsink), and only open the stencil at the headsink pad. Apply tacky flux on the I/O pads at PCB after paste printing process.... -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Thursday, 30 April 2009 4:12 AM To: [log in to unmask] Subject: Re: [TN] Actel QFN180 Assembly Yes, Steve, I have, outside of GD. It is not fun, very frustrating. The only tip I can give you is to try using some Kapton tape to experiment with the aperture openings until you think you have what you need, then remember to account for the one mil thicker deposit on account of the tape. Hopefully the next iteration will be the last. However, I also had so many issues with the exposed copper on the edges of many of the QFNs and the unevenness and the huge delta CTE issues that I just decided it was not worth it to screw around with it anymore. Here at GD we do not use QFN packages, we repackage them. We also work with the component manufacturer to give us the part in a different package. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Wednesday, April 29, 2009 2:32 PM To: [log in to unmask] Subject: Re: [TN] Actel QFN180 Assembly Hi Jim, Just having issues trying to find the right balance between the thermal pad and I/O pad opening dimensions in the stencil. We're about to go on our third stencil iteration and have a good idea what we're going to do, but it's frustrating when you follow the design guidelines that the manufacturer of the device say to do, and they don't work. But why should I be surprised at that? Sheesh... Just wondering if others go through this drill too? Steve -----Original Message----- From: Jim Wolvansky [mailto:[log in to unmask]] Sent: Wednesday, April 29, 2009 12:23 PM To: Steve Gregory Subject: RE: [TN] Actel QFN180 Assembly Hello, Steve. I've got some experience with devices like these, what issues are you having? - Jim -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Wednesday, April 29, 2009 9:11 AM To: [log in to unmask] Subject: [TN] Actel QFN180 Assembly Hi All, We just ran a board with an Actel QFN180 device, and followed the stencil guidelines recommended by Actel in their publication: http://www.actel.com/documents/QFN_AN.pdf but we have had our issues. I was wondering if anyone else has used this component and would be willing to share their experience with it. We'll figure out things eventually, but I figure it wouldn't hurt to ask for some advice from this wonderful group. Thanks, Steve --------------------------------------------------- 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 -----------------------------------------------------